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CMS Physics Analysis Summary

Contact: cms-pag-conveners-susy@cern.ch 2012/05/03

Interpretation of Searches for Supersymmetry with

Simplified Models

The CMS Collaboration

Abstract

The results of CMS searches for Supersymmetry are interpreted in the context of Simplified

Models. These results are based on data samples with a corresponding integrated

luminosity of up to 4.98 fb −1 produced in proton–proton collisions at a centerof-mass

energy of 7 TeV collected by the CMS experiment at the LHC. This analysis

provides a compilation of acceptance predictions and cross section upper limits for

a range of Simplified Models and mass parameters. The results provide information

that can be used to constrain other theoretical models. They also provide a comparison

of different CMS search strategies.


1 Introduction

Several analyses [1–15] have been performed in CMS with data recorded in 2011 searching for

signs of new physics as expected in models of Supersymmetry (SUSY). The results of these

searches are summarized and compared in the context of simplified model spectra (SMS) [16–

22]. A smaller number of SMS were investigated with the data recorded in 2010 [23, 24]. The

ATLAS collaboration has published similar results [25–30].

The results of SUSY-inspired searches by CMS have been interpreted in terms of the constrained

minimal supersymmetric extension of the Standard Model (cMSSM) [31] and the generalized

gauge-mediation model (GGM) [32]. The constrained SUSY models provide a useful framework

for exploring a variety of theoretical and experimental ideas. They reduce the large

number of SUSY parameters to a manageable level, so that a few benchmarks can be used

to compare the observed limits and assess the expected sensitivity of different search strategies.

However, the constrained models predict specific mass patterns and signatures which are

not indicative of the general MSSM or extensions.

In SMS, a limited set of hypothetical particles and decay chains are introduced to produce a

given topological signature. The amplitudes describing the production and decays of these

particles are parametrized in terms of the particle masses and their branching ratios to daughter

particles. SMS provide a benchmark different from the constrained models for comparing

search strategies which is more sensitive to the choice of kinematic selections and the final state

topology. Furthermore, the tabulation of signal acceptance and the 95% exclustion limit on the

signal cross section as a function of the mass parameters of a SMS can be used as a reference to

place limits on different theoretical models.

The paper is organized as follows: Section 2 provides a summary of the CMS analyses used

in this analysis, and reviews their interpretation within the cMSSM; Section 3 introduces a

description of the simplified models used for the interpretation of these analyses; Section 4

contains the results of the simplified model interpretation; and, Section 5 contains conclusions.

The Appendix provides details on the simulation of the SMS signals.

2 CMS SUSY-inspired Analyses and cMSSM Interpretation

This section introduces the analyses and the experimental results that are reinterpreted using

SMS. Detailed descriptions of the analyses can be found in the references [2–5, 9–11, 13–15].

The results are based on data ranging from 1 to 4.98 fb −1 of integrated luminosity as stated in

the text, collected with the CMS detector from pp collisions at the LHC and at a center-of-mass

energy of 7 TeV.

All of the analyses considered search for an excess of events over Standard Model (SM) predictions

and require substantial missing transverse momentum (ET).

1. All-hadronic (“hadronic”) Events are selected with multiple jets and ET, as expected from

gluino and squark production and decay. Different methods and observables, αT [2] and

HT +jets [3], are employed to suppress multi-jet backgrounds. Events with isolated leptons

are vetoed to reduce backgrounds from SM top and W boson production. A dataset

of 1 fb −1 is analyzed.

2. All-hadronic events with b-jets (“hadronic+b-jets”) Events are selected with multiple

jets, at least one of which must be b-tagged, no isolated leptons and large ET [5] or large

1


2 2 CMS SUSY-inspired Analyses and cMSSM Interpretation

MT2 [4]. These searches are motivated by the possibility that top or bottom squarks are

lighter than the other squarks, and can bias SUSY signatures to final states with b-jets. A

dataset of 1 fb −1 is analyzed.

3. Single-lepton (“leptonic”) The single-lepton analysis uses the observed lepton transverse

momentum (pT) spectrum and other control samples to predict the ET spectrum

associated with the SM background, and searches for deviations [15]. This measurement

is sensitive to sparticle decays to LSPs, in which the ET distribution is decoupled from the

lepton pT spectrum. A dataset of 4.7 fb −1 is analyzed.

4. Opposite-sign di-leptons (“OS di-leptons”) Events are selected with opposite-sign leptons

in the presence of jets and ET, as expected from decays of charginos and neutralinos

produced in squark or gluino cascade decays [10]. Two complementary search strategies

are pursued. In the first case, different signal regions are used requiring cuts on ET and

the scalar sum of the transverse jet energies (HT). In the second case, is performed a

dedicated search for a characteristic kinematic edge in the dilepton mass distributions. A

dataset of 4.98 fb −1 is analyzed.

5. Same-sign di-leptons (“SS di-leptons”) Events are selected with same-sign leptons (electrons

and muons) and large ET, as expected from SUSY signatures sensitive to the Majorana

nature of gluinos and neutralinos [9]. Two data samples are used: the inclusive

di-lepton sample, which is based on calorimeter triggers, and the high-pT di-lepton sample,

which is based on lepton triggers. Different combinations of ET and HT cuts are used

for further background suppression. A dataset of 4.98 fb −1 is analyzed.

6. Same-sign di-leptons and b-jets (“SS di-leptons+b-jets”) Events are selected with SS

dileptons in association with at least one b-tagged jet and large ET, as expected from the

production and decay of gluinos to top or bottom squarks [13]. A dataset of 4.98 fb −1 is

analyzed.

7. Di-leptons from Z boson decay (“Z di-leptons”) Events are selected with a pair of sameflavor,

opposite-charge electrons or muons from a Z boson decay accompanied by jets

and ET [14]. One search relies on control samples with similar hadronic activity to model

ET, while the other exploits the pT balance of the Z boson and the jets. A dataset of 4.98

fb −1 is analyzed.

8. Multi-leptons (“multi-leptons”) Events are selected containing at least three leptons [11].

Backgrounds are suppressed with cuts on several event variables, including ET, the invariant

mass of lepton pairs, and the hadronic activity. These searches are motivated by

signatures arising from the decay of charginos or neutralinos, produced either directly or

in cascade decays of heavier squarks or gluinos. A dataset of 4.7 fb −1 is analyzed.

All of the CMS searches considered interpret their experimental results in terms of the (m0,m 1/2)

plane of the cMSSM. For tan β = 10, A0 = 0 GeV, and µ > 0, the CMS data collected with up

to 1 fb −1 of integrated luminosity exclude squark masses < 1000 GeV/c 2 and a gluino mass

< 750 GeV/c 2 . However, the exclusion depends upon the mass hierarchies and the contributions

of many different production processes and decay chains as predicted for this set of

cMSSM parameters. A variation of tan β, A0, and sgn(µ) would alter the exclusion results,

but would not cover all reasonable mass hierarchies and combinations of processes. The SMS

interpretation of the same analyses provide more general exclusion limits.


3 Simplified Model Spectra

This section describes the relevant topologies for reinterpreting the analyses described in Section

2. A list of SMS topologies and the analysis channels that are sensitive to each is provided

in Table 1.

The SMS studied here are chosen because they are motivated by plausible SUSY signatures,

and current searches would be sensitive to them. The SUSY particle terminology is adopted for

new particles: gluino (g), squark (q), neutralino (χ 0 ) and chargino (χ ± ). The lightest of all new

particles is assumed to be neutral, and is referred to as the lightest supersymmetric particle

(LSP). This particle is the lightest neutralino χ 0 or a gravitino G in the topologies studied here.

While the SUSY terminology is employed, interpretations in terms of SMS are not restricted to

SUSY scenarios.

It is assumed that new particles are produced in pairs. In the SMSes, the produced particle

decays either directly to the LSP and SM particles, or to an intermediate, on-shell particle,

which decays directly to the LSP and SM particles. For each SMS, samples are generated for a

range of masses of the particles involved, providing a wider spectrum of mass splittings than

allowed by the cMSSM. The primary step in reinterpreting an analysis in the SMS is to calculate

the selection efficiency and the 95% C.L. upper bound on the allowed production cross

section (times branching ratios) as a function of these masses. The selection efficiency is calculated

using PYTHIA 6.426 [33] with Tune Z2 [34] [35] to produce signal events as an input to

a parametrized simulation of the CMS detector called “Fastsim” [36] to produce reconstructed

events.

For guidance, the cross section upper bound is compared to a reference cross section for SUSY

production processes calculated at next to leading order (NLO) precision using PROSPINO [37]

and CTEQ6 parton distribution functions [38]. The reference cross section is scaled by a factor

3 or 1/3 to demonstrate the effect of cross section variations, which could arise from different

assumptions about the spin or other quantum numbers of the produced particle, or branching

ratio variations [20].

When the mass splitting between the mother particle and the LSP is small, and the event selection

demands ET much larger than this splitting, the signal efficiency predicted by event

generators becomes more sensitive to the choice of generator parameters. In the presentation

of results, a cut on small mass splitting between the mother particle and the LSP and on small

particle masses is applied to remove sensitivity to statistical errors and signal modeling. The

specific choice depends upon the analysis, and is usually set by the ET or HT threshold.

3.1 SMS Construction

Each SMS is specified by a production process and decay modes. The production processes

considered are q ¯q, gg → gg or q ¯q, gg → qq ∗ or q ¯q → χ 0 χ 0 and q ¯q → χ 0 χ ± . Distinct SMS are

also produced where the q is specifically a top squark or a bottom squark.

The decays considered are to final states containing either two or three particles, denoted as

2-body or 3-body decays, respectively. A three particle final state can be obtained through

a direct 3-body decay of the mother particle, or through a series of two 2-body decays. The

latter case introduces the additional choice of an intermediate particle mass. The decay of a

chargino to leptons and the LSP (χ ± → lν χ 0 ) can proceed directly or through several decay

chains: χ ± → W ± χ 0 , χ ± → ℓ(→ ℓ χ 0 )ℓ or χ ± → ν(→ ν χ 0 )ℓ. Since the kinematics of the

charged lepton will be different in each case, a particular choice is made based on the expected

sensitivity of the analyses. Another example is the final state of 4 W bosons, 4 b quarks and

3


4 3 Simplified Model Spectra

LSPs, which is modeled with gluino pair production, followed by the decay g → t¯t χ 0 , but could

also be modeled by g → t¯t,t → t χ 0 . Generator level studies indicate that the top quarks are

produced with only a small correlation to their mother’s direction, and not with large boosts,

in either scenario. Full simulation studies support this result [13].

Each SMS is labeled using the mnemonic TNx. “T” is universal, and refers to a topology. “N” is

a number ranging from 1 to 6. Odd N refers to gluino pair production, in the QCD limit (with

the squark decoupled), while even N refers to squark anti-squark production, in the QCD limit

(with the gluino decoupled). N refers to different hierarchies of decays for the two produced

mothers: N=1(2) for direct decays, N=3(4) for one direct decay, one cascade decay, and N=5(6)

for two cascade decays, for gluino (squark) production. “x” is a string that describes the final

state when necessary. The mnemonic has been adapted to the production of charginos and

neutralinos by replacing “TN” with “TChi”.

The simplest SMSes that cover the hadronic jets + ET analyses are gluino pair production with

the direct decay g → q ¯q χ 0 (T1), and squark-antisquark production with the direct decay q →

q χ 0 (T2), illustrated in Figure 1. The free parameters of T1 (T2) are the gluino (squark) and

the χ 0 masses. For b-enriched SMS, gluino pair production with the direct decay g → b ¯ b χ 0

(T1bbbb) has been considered. The corresponding SMS with the direct decay g → t¯t χ 0 (T1tttt)

has also been considered. These are illustrated in Figure 2. 1

P2

P1

˜g

˜g

q

¯q

¯q

q

˜χ 0 1

˜χ 0 1

Figure 1: Diagrams of the hadronic models: gluino pair production (T1,left) and squark antisquark

production (T2,right).

P2

P1

˜g

˜g

b

¯ b

¯ b

b

˜χ 0 1

˜χ 0 1

Figure 2: Diagrams of the heavy flavor models: T1bbbb (left), T1tttt (right).

Additional models are constructed by adding an intermediate particle in the decay chain, so

that the gluino can undergo a direct three-body decay into jets and a chargino or a neutralino

that is heavier than the LSP. Such SMS are illustrated in Figures 3 and 4. Both the chargino and

1 The sbottom antisbottom direct production with direct decay to b and χ 0 will be referred to as T2bb.

P2

P1

P2

P1

˜q ∗

˜q

˜g

˜g

¯q

q

t

¯t

¯t

t

˜χ 0 1

˜χ 0 1

˜χ 0 1

˜χ 0 1


3.1 SMS Construction 5

the neutralino would then subsequently decay into a gauge boson and χ 0 or undergo a 3-body

decay including the LSP.

The SMS with cascade decays are interesting to study, since the amount of energy available for

the LSP is reduced, for a fixed mother mass, as when there is a direct decay. When gluinos

undergo cascade decays, the number of jets per event is expected to be greater than for direct

decays, and the spectrum of jet energies will depend on the ratio of gaugino masses. The

presence of cascade decays may be a benefit or detriment, depending on the analysis.

P2

P1

˜g

˜g

˜χ 0 2

q

¯q

¯q

˜χ 0 l

1


l +

˜χ

q

0 1

Figure 3: Diagrams of the dilepton models: T3lh (left), T5lnu (right).

P2

P1

˜g

˜g

˜χ ±

q

W ±

¯q

¯q

˜χ 0 1

˜χ

q

0 1

P1

P2

P2

P1

Figure 4: Diagrams of T3w (left), T5zz (right).

The mass of the intermediate particle for cascade decays is specified by the formula [21]

with x = 1 1

4 , 2

˜g

˜g

˜g

˜g

˜χ ±

˜χ ±

˜χ 0 2

˜χ 0 2

q ¯q

ν l±

˜χ 0 ˜χ

1

0 l

1

±

¯q

q

ν

q

¯q

¯q

˜χ

Z

Z

0 1

˜χ

q

0 1

m χ 0 2 |m χ ± = x · m g + (1 − x) · m χ 0, (1)

3 , and 4 , chosen to yield different kinematics for the intermediate particle, and

avoid the region where the intermediate particle is effectively the mother (x = 1) or the LSP

(x = 0).

In the T3lh and T5lnu SMS, the neutralino or chargino, respectively, undergoes a 3-body decay

to leptons and the LSP. The intermediate particle mass is fixed at x = 1

2 . T3lh is characterized

by the OS lepton edge, 2 while T5lnu produces SS lepton pairs and OS lepton pairs with equal

probability. The leptons are produced democratically in the three families (e,µ,τ).

The SMS T3w includes one gluino decaying directly to the LSP, and the other decaying to an

intermediate chargino, with χ ± → W ± χ 0 . In T5zz, the intermediate neutralino subsequently

decays to a Z boson and the LSP, yielding a final state with two Z bosons. In case Eq. 1 does

not allow for the decay to an on-shell Z boson, the intermediate particle mass is shifted to

2 In the 3-body decay g → f ¯ f χ 0 , the invariant mass of the f ¯ f is bounded by mg − m χ 0


6 4 Results with Simplified Models

m χ 0 2 = 1.01MZ. For the T5zz and T3w, the intermediate χ 0 2 and χ± mass are specified with

x = 1 1 3

4 , 2 , and 4 . The weak bosons decay inclusively, producing final states with combinations

of jets and leptons.

Illustrations of the SMS for chargino and neutralino direct production are given in Figure 5.

TChiwz and TChiSlepSlep are models of the associated production of a chargino and a neutralino.

In TChiwz, the chargino and neutralino decay to a W boson and LSP and a Z boson

and LSP, respectively. In TChiSlepSlep, an intermediate slepton is introduced with a mass equal

to the average of the chargino and LSP mass. TChizz is a model of the associated production

of neutralinos. This process is modeled by the production of a pair of different neutralinos,

χ 0 2 χ0 3 , with similar masses, as can be realized in a light Higgsino model. These processes have

kinematics similar to chargino-neutralino production.

P2

P1

P2

P1

˜χ 0 3

˜χ 0 2

˜χ 0 2

˜χ ±

Z

Z

˜ l

˜ l

l

ν

l

l

˜χ 0 1

˜χ 0 1

˜χ 0 1

˜χ 0 1

Figure 5: Diagrams of chargino and neutralino production: TChizz (left,top) TChiwz

(right,top), and TChiSlepSlep (bottom).

4 Results with Simplified Models

4.1 Results for models with hadronic decays

Two searches probe the all-hadronic channels – the αT and the high-HT + jets searches. These

analyses are interpreted in the SMS T1, T2, and T5zz (x= 1

2 as defined in Eq. 1).

The αT variable is a kinematic discriminant that can be used to select events with real ET balancing

a dijet system. The αT analysis [2] searches for an excess of events in data over the

SM expectation for large αT and HT above 275 GeV. Figure 6 (left) shows the signal selection

efficiency as a function of the mother and LSP mass for the T1, T2, and T5zz topologies, respectively.

Only the lower half of the plane is filled because the LSP must be lighter than the mother

particle.

The signal selection efficiency increases for higher mother particle masses, and decreases towards

the diagonal, where the mass splitting is small and jets are produced with lower transverse

momentum. The overall selection efficiency of this analysis decreases for a fixed mother

P2

P1

˜χ 0 2

χ ˜±

Z

W

˜χ 0 1

˜χ 0 1


4.1 Results for models with hadronic decays 7

prod.

name mode decay visibility section document

T1 gg g → qq χ 0 hadronic 4.1 [2, 3]

T2 qq q → q χ 0 hadronic 4.1 [2, 3]

T5zz gg g → qqZ χ 0 hadronic 4.1 [2, 3]

di-leptons 4.3 [14]

T3w gg g → qq χ 0 single lepton 4.2 [15]

g → qq χ ± , χ ± → W ± χ 0

T5lnu gg g → qq χ ± χ ± → lν χ 0 di-leptons 4.4 [9]

T3lh gg g → qq χ 0 di-leptons 4.4 [10]

g → qqll χ 0

T1bbbb gg g → bb χ 0 hadronic 4.5 [4, 5]

T1tttt gg g → tt χ 0 hadronic 4.6 [5]

di-leptons(b) [9, 13]

TChiSlepSlep χ ± χ 0 2 χ 0 2 → l˜ l , ˜ l → l χ 0 multi-leptons 4.7 [11]

χ ± → ν ˜ l , ˜ l → l χ 0

TChiwz χ ± χ 0 2 χ ± → W ± χ 0 , χ 0 2 → Z χ0 multi-leptons 4.7 [11]

TChizz χ 0 2 χ0 3 χ 0 2 , χ0 3 → Z χ0 multi-leptons 4.7 [11]

Table 1: Summary of the simplified models used in this document.

and daughter mass as the number of partons in the final state increases, as seen by comparing

the T2 (2 jets), T1 (4 jets) and T5zz (4–8 jets) results. For low LSP mass, the αT selection is

inefficient, because the fraction of visible energy in the final state increases. In general, the αT

variable is more sensitive when HT is comparable to HT.

Figure 6 (right) displays the 95% CL upper limits on the T2, T1, T5zz topology as a function

of the mother and LSP mass. The contours illustrate where the reference cross section and the

upper limit on the cross section intersect. The T1 limit is better than the T2 limit, despite the

fact that gluino cascade decays lead to a higher number of jets in the final state. This is related

to the larger expected cross section for a color octet fermion, since the T2 efficiency is better. It

is important to note that the T1 and T5zz topologies have the same mother (gluino), and hence

the same reference cross section. The reduction in sensitivity for T5zz at each (mother, LSP)

point is directly related to the presence of cascade decays.

The HT + jets analysis [3] is based on the selection of three or more high transverse momentum

jets whose transverse vector sum yields a large pT imbalance (HT). Several HT and HT cut

combinations are considered to maintain sensitivity to different mass hierarchies. The overall

selection efficiency of this analysis is higher for the T1 topology, with more partons in the final

state, than for the T2 topology. This is not surprising, since this analysis requires at least three

high-pT jets. Different selections are shown to better cover different regions of phase space:

the looser requirement on the HT and ET has a better sensitivity for small mother-LSP mass

splitting; for higher mass splitting, instead, the tight selection is more sensitive; the high HT

and low HT selection are better suited for long cascade decay with more visible energy in the

final state, as expected in the T5zz topology. Figure 7 (left) shows the selection that has the best

expected cross section upper limit, and (right) the upper limits on the product of the production

cross section and the branching ratio. As in the case of αT, the limit for T5zz is degraded with


8 4 Results with Simplified Models

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Figure 6: Total αT selection efficiency (left) and 95% CL upper limits on the gluino and squark

pair-production cross sections (right) for the topologies T2 (top), T1(middle) and T5zz (bottom)

as a function of gluino or squark mass and the LSP mass.

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4.1 Results for models with hadronic decays 9

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ET

+ jets: OR all selection

prod NLO-QCD

σ = σ

prod

NLO-QCD

σ = 3 × σ

prod

NLO-QCD

σ = 1/3 × σ

400 600 800 1000 1200

m~

(GeV) q

pp →

~

g

~

g,

~

g → 2q + LSP; m(

~

q)>>m(

~

g)

800

600

400

200

400 600 800 1000 1200

m~

(GeV) g

10

1

-1

10

-2

10

s

(pb) (CL

σ

95% CL upper limit on

1200 )

pp →

1000

800

600

400

200

CMS Preliminary

-1

s = 7 TeV L=1.1 fb

ET

+ jets: OR all selection

prod NLO-QCD

σ = σ

prod

NLO-QCD

σ = 3 × σ

prod

NLO-QCD

σ = 1/3 × σ

~

0 0

g

~

g,

~

g → 2q + χ , χ → Z + LSP;m(

~

q)>>m(

~

g)

400 600 800 1000 1200

m~

(GeV) g

10

1

-1

10

-2

10

s

(pb) (CL

σ

95% CL upper limit on

1200 )

CMS Preliminary

-1

s = 7 TeV L=1.1 fb

ET

+ jets: OR all selection

prod NLO-QCD

σ = σ

prod

NLO-QCD

σ = 3 × σ

prod

NLO-QCD

σ = 1/3 × σ

Figure 7: HT +jets: Selection that has the best expected cross section upper limit (left) and 95%

CL upper limits on the squark/gluino pair-production cross sections (right) for the topologies

T2 (top), T1 (middle) and T5zz (bottom) as a function of the gluino and LSP mass.

10

1

-1

10

-2

10

s

(pb) (CL

σ

95% CL upper limit on


10 4 Results with Simplified Models

respect to T1, illustrating the impact of cascade decays.

For both the αT and HT +jets analyses, results are presented only for mother masses above

300-400 GeV, and for mass splittings above typically 200 GeV, to remove sensitivity to event

generation.

4.2 Single Lepton Inclusive Analyses

LSP mass [GeV]

g )

900

CMS Preliminary

~

± 0 ± 0

pp →

~

g

~

g,

~

g → qq(


χ |


χ ),


χ → W


χ ; m(

~

q)>

> m(

800

700

600

500

400

300

200

100

s = 7 TeV,

e/ µ

400 600 800 1000

gluino mass [GeV]

0

χ ) + 0.25 m(

~

g)


±

χ ) = 0.75 m(


m(

LSP mass [GeV]

800

700

600

500

400

300

200

100


spectrum

HT

> 500, all ET

bins

­1

Ldt=4.98 fb

g )

900

CMS Preliminary

~

± 0 ± 0

pp →

~

g

~

g,

~

g → qq(


χ |


χ ),


χ → W


χ ; m(

~

q)>

> m(

s = 7 TeV,

e/ µ

400 600 800 1000

gluino mass [GeV]

0

χ ) + 0.25 m(

~

g)


±

χ ) = 0.75 m(


m(


spectrum

NLO­QCD

σ

NLO­QCD

3 × σ

­1

Ldt=4.98 fb

0.1

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0

10

1

­1

10

­2

10

ε

×

A

)

s

[pb] (CL

σ

95% CL upper limit on

LSP mass [GeV]

g )

900

CMS Preliminary

~

~ ~ ~

± 0 ± 0 ~

pp → g g,

g → qq(


χ |


χ ),


χ → W


χ ; m( q)>

> m(

800

700

600

500

400

300

200

100

s = 7 TeV, ∫

e/ µ

spectrum

HT>500

GeV

HT>750

GeV

HT>1000

GeV

­1

Ldt=4.98 fb

Most sensitive selection

400 600 800 1000

gluino mass [GeV]

∼±

∼0

~

m( χ ) = 0.75 m( χ ) + 0.25 m( g)

[pb]

σ

95% CL upper limit on

10

2

10

1

-1

10

± 0 ± 0

pp →

~

g

~

g,

~

g → qq( χ | χ ), χ → W χ ; m(

~

q)>>m(

~

g)

m(LSP) = 50 (GeV)

CMS Preliminary

s = 7 TeV ∫

e/ µ

spectrum

-1

L dt = 4.98 fb

σ (

~

g

~

g)

(Prospino)

NLO

±

0

m( χ )=0.25 m( χ )+0.75 m( g~ )

0

m( χ±

)=0.50 m( χ )+0.50 m( g~ )

0

m( χ±

)=0.75 m( χ )+0.25 m( g~ )

400 600 800 1000

gluino mass [GeV]

Figure 8: T3w topology and single lepton analysis: Typical signal selection acceptance times efficiency

for HT > 500 GeV (top, left); HT selection that yields the best expected limit (top, right)

and upper cross section limits as a function of the gluino and LSP mass for the intermediate

chargino (bottom, left); and the limits for different locations of the chargino mass and fixed LSP

as defined in Eq. 1.

mass (bottom right). The first three figures are for x = 1

4

This analysis studies the distributions of a single lepton (e or µ) produced in association with

ET and large HT for deviations from the SM expectations from W+jets and t¯t production [15].

Several HT and ET cut combinations are considered to maintain sensitivity to different mass

hierarchies. The results have been interpreted in the context of the T3w topology characterized

by the presence of a W boson and many jets.

The signal selection acceptance times efficiency is shown in Figure 8 (left, top). The main pa-


4.3 Dileptons from Z boson decays 11

rameter affecting the sensitivity is the mass splitting between the gluino and the LSP. The efficiency

shown includes the penalty for obtaining a lepton from the inclusive decays of the

W boson (33%). Figure 8 (top, right) shows the minimum HT selection that yields the best expected

limit for the case in which the chargino mass in the decay chain is closer to the LSP mass

(x = 1

4 ). In this case, the selection with the lowest HT requirement yields the best sensitivity,

except for very large mass splittings. For the other mass hierarchies investigated (x = 1

2 and

x = 3

4 ), the selection with the lowest HT requirement always yields the best expected limit.

Figure 8 (bottom, left) shows the cross section upper limit; Figure 8 (bottom, right) compares

the cross section upper limit for different choices of x values as a function of the gluino mass.

The effect of signal contamination increases with x, as the chargino mass approaches the gluino

, decreasing to 10% or less

mass. A signal contamination of 30% has been estimated for x = 3

4

for x = 1

4 .

4.3 Dileptons from Z boson decays

Two analyses reconstruct the Z boson in its decay to e + e − or µ + µ − pairs accompanied by jets

in the final state: one uses a ET selection; the other uses the balance between the reconstructed

Z boson and the jet recoil (JZB) [14]. The JZB search relies on the correlation between the Z

boson and the ET directions, which leads to an asymmetry in the JZB distribution for signal

events. These analyses can be reinterpreted using the T5zz topology, which can lead to signatures

with a Z boson decaying leptonically and ET. In both analyses, more than one signal

region is defined with a loose or tight requirement on the main discriminating variable (ET or

JZB).

The effect of the selection is investigated in two scenarios: in the first case, the mass of the

LSP is fixed to zero and the gluino and intermediate neutralino masses vary; in the second

case, the mass of the intermediate particle is fixed to x = 1

1

4 ( the other cases x = 2

, x = 3

4

are documented in [14]). In Figures 9 and 10, the signal acceptance times efficiency (left)

and cross section upper limit (right) for the ET analysis (top) and JZB analysis (bottom) are

shown for these two scenarios. The signal acceptance times efficiency is calculated as the ratio

of events passing the selection relative to the number of events generated that already contain

a prompt lepton (e, µ, τ) from the Z boson decay. The sensitivity of the JZB search is reduced

for mass spectra that lead to a symmetric distribution of the JZB variable, as demonstrated for

the case of a massless LSP.

Figure 11 shows the cross section upper limit in the ET search for a massless LSP as a function of

the gluino mass for a few values of the intermediate neutralino mass. These limits are relatively

insensitive to the gluino mass, indicating that the main feature of the signal is the decay χ 0 →

Z G.

4.4 Di-leptons

Pairs of same-sign (SS) and opposite-sign (OS) leptons not arising from Z boson decays are

present in the T5lnu and T3lh topologies. These SMS are interpreted using the SS and OS

dilepton analyses, respectively.

Results for the T5lnu topology using the SS dilepton selection are shown in Figure 12. For the

SS dilepton analysis, two lepton selections (low and high pT) and several HT and ET selections

are investigated [9]. The selection providing the best expected sensitivity is shown in Fig. 12

(top). Figure 12 (bottom, left) shows the selection efficiency for the high ET selection, which is

most sensitive for large mass splitting. For each combination of masses, the selection that provides

the best expected limit is chosen, and the cross section upper limit is shown in Figure 12


12 4 Results with Simplified Models

mass [GeV]

χ0

1

mass [GeV]

0 χ

1

0 0

pp → g

~

g

~

, g

~

→ 2j+ χ , χ → Z G

1 1

0.3 Z(ll))

1000 m( q

~

) >> m( g

~

)

1

800

600

400

200

1000

800

600

400

200

CMS,

miss

ET

njets

≥ 2

miss

ET

-1

s = 7 TeV, L = 4.98 fb

int

> 100 GeV

templates

0 200 400 600 800 1000

gluino mass [GeV]

CMS,

-1

s = 7 TeV, L = 4.98 fb

int

0 0

pp → g

~

g

~

, g

~

→ 2j + χ , χ →

1 1

m( q

~

) >> m( g

~

)

JZB > 150 GeV

njets

≥ 3

G ~

Z

0 200 400 600 800 1000

gluino mass [GeV]

0.35

0.25

0.2

0.15

0.1

0.05

0

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00


(

ε

×

A

1 Z(ll))


(

ε

×

A

mass [GeV]

0 χ

1

mass [GeV]

0 χ

1

1000

800

600

400

200

CMS,

0 0

pp → g

~

g

~

, g

~

→ 2j+ χ , χ → Z G

1 1

m( q

~

) >> m( g

~

)

njets

≥ 2

miss

ET

σ

3 × σ

1/3 × σ

NLO-QCD

-1

s = 7 TeV, L = 4.98 fb

int

NLO-QCD

NLO-QCD

templates

0 200 400 600 800 1000

gluino mass [GeV]

1000

800

600

400

200

0 0

pp → g

~

g

~

, g

~

→ 2j + χ , χ →

1 1

m( q

~

) >> m( g

~

)

njets

JZB

≥ 3

σ

3 × σ

1/3 × σ

NLO-QCD

-1

s = 7 TeV, L = 4.98 fb

int

NLO-QCD

NLO-QCD

G ~

Z

0 200 400 600 800 1000

gluino mass [GeV]

Figure 9: T5zz topology: Signal selection acceptance times efficiency normalized to the events

where there is at least one Z boson decaying leptonically (e, µ, τ) (left), and upper cross section

limits on the inclusive Z boson decay mode (right) for the ET (top) and JZB (bottom) analyses.

Results are shown as a function of gluino and intermediate neutralino mass NLSP for a

massless LSP. Please note the deviation from the document’s standard naming convention: the

intermediate neutralino is named χ 0 1 , the LSP is denoted by G.

(bottom, right).

Similar results are shown in Figure 13 for T3lh using the OS analysis [10] for the HT and ET

selections (bottom) and the reconstruction in the dilepton invariant mass (top). The kinematic

edge search allows looser cuts compared to the OS counting experiment that results in a exclusion

curve that is almost independent of the mass splitting, for m χ 0 < 500 GeV for one, while

the exclusion curves becomes horizontal near m χ 0 = 400 GeV for the other.

The SS dilepton analysis also is particularly more sensitive than the OS analysis to smaller mass

splitting.

The SS dilepton analysis is more sensitive to smaller mass splitting: the exclusion curve is

almost independent of mass splitting up to m χ 0 = 400 GeV, whereas the OS dilepton analysis

CMS,

10

1

-1 10

-2 10

-3

10

[pb]

σ

95% CL upper limit on

10

1

-1

10

-2

10

-3

10

[pb]

σ

95% CL upper limit on


4.5 b-rich final states 13

mass [GeV]

χ0

1

mass [GeV]

0 χ

1

0 0 0

pp → g

~

g

~

, g

~

→ 2j+ χ , χ → Z χ

2 2 1

Z(ll))

1000 m( q

~

) >> m( g

~

), x = 0.25

0.3

1

800

600

400

200

1000

800

600

400

200

CMS,

miss

ET

njets

≥ 2

miss

ET

-1

s = 7 TeV, L = 4.98 fb

int

> 100 GeV

templates

0 200 400 600 800 1000

gluino mass [GeV]

CMS,

-1

s = 7 TeV, L = 4.98 fb

int

0 0

pp → g

~

g

~

, g

~

→ 2j + χ , χ → Z χ

2 2

m( q

~

) >> m( g

~

), x = 0.25

JZB > 150 GeV

njets

≥ 3

0 200 400 600 800 1000

gluino mass [GeV]

0

1

0.35

0.25

0.2

0.15

0.1

0.05

0

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00


(

ε

×

A

1 Z(ll))


(

ε

×

A

mass [GeV]

0 χ

1

mass [GeV]

0 χ

1

1000

800

600

400

200

CMS,

0 0

pp → g

~

g

~

, g

~

→ 2j+ χ , χ → Z χ

2 2

m( q

~

) >> m( g

~

), x = 0.25

njets

≥ 2

miss

ET

σ

3 × σ

1/3 × σ

NLO-QCD

-1

s = 7 TeV, L = 4.98 fb

int

NLO-QCD

NLO-QCD

templates

0 200 400 600 800 1000

gluino mass [GeV]

1000

800

600

400

200

0 0

pp → g

~

g

~

, g

~

→ 2j + χ , χ → Z χ

2 2

m( q

~

) >> m( g

~

), x = 0.25

njets

JZB

≥ 3

σ

3 × σ

1/3 × σ

NLO-QCD

-1

s = 7 TeV, L = 4.98 fb

int

NLO-QCD

NLO-QCD

0 200 400 600 800 1000

gluino mass [GeV]

Figure 10: T5zz topology: Signal selection acceptance times efficiency normalized to events

where there is at least one Z boson decaying leptonically (e, µ, τ) (left), and upper cross section

limits on the inclusive Z boson decay mode (right) for the ET (top) JZB (bottom) analyses.

Results are shown as a function of the gluino and LSP mass χ0 1 , with the intermediate neutralino

χ 0 2

mass set using x = 1

4 .

exclusion curve becomes horizontal near m χ 0 = 300 GeV. For larger mass splittings, the OS

dilepton analysis has roughly 25 GeV more reach in gluino mass.

4.5 b-rich final states

Two analyses investigate the heavy flavor content of events with large ET and HT, requiring

jets in the final state that are b-tagged. These two analysis use different observables to suppress

the SM background: ET [4] and MT,2 [5], and are denoted as ET +b and MT,2b, respectively. The

results are interpreted as a function of m g and m χ 0 for the T1bbbb model.

For the ET +b analysis, the selection yielding the best expected limit (top), the selection efficiency

(left, bottom) and cross section upper limits (right, bottom) are shown in Figure 14. Exclusion

limits, assuming our reference cross section and branching fraction of unity, are shown

also. The best expected limit for each point is chosen from two different selections requiring

CMS,

0

1

0

1

10

1

-1 10

-2 10

-3

10

[pb]

σ

95% CL upper limit on

10

1

-1

10

-2

10

-3

10

[pb]

σ

95% CL upper limit on


14 4 Results with Simplified Models

[pb]

σ

4

10

3

10

2

10

10

1

-1

10

-2

10

-3

CMS preliminary

-1

s = 7 TeV, ∫L

dt = 4.98 fb

σ(pp→

~

g

~

g)

NLO-QCD

0 σ M( χ ) = 100 GeV

UL 1

0 σ M( χ ) = 300 GeV

UL 1

0 σ M( χ ) = 500 GeV

UL 1

0 0

pp → g

~

g

~

, g

~

→ 2j+ χ , χ → Z G

1 1

m( q

~

)>>m( g

~

)

miss

ET

templates, n ≥ 2

jets

10

200 300 400 500 600 700 800 900 1000 1100

gluino mass [GeV]

Figure 11: The upper limit on cross section times branching ratios is shown as function of

gluino mass and several masses for the intermediate neutralino with a massless LSP.

one or two jets with a b-tag in addition to a requirement of large HT and ET.

As for many other analyses, the mass splitting between the mother and the LSP is the parameter

which has the largest impact on the sensitivity for a fixed mother mass. For small mass splitting,

the best sensitivity is obtained with two loose b-tagged jets. For larger mass splitting, the signal

decay products have more energy in the final state, and a selection with one tight b-tag gives a

better sensitivity.

For the MT,2b analysis, the selection efficiency (left) and the cross section upper limit (right)

are presented in Figure 15. The selection optimization in ET +b yields comparatively better

sensitivity for small mass splittings.

4.6 t-rich final states

The SS dilepton [5] and the ET +b fully hadronic analysis [9] with 1 fb −1 are re-interpreted in

the SMS T1tttt, characterized by 4 t-quarks in the final state.

Figures 16 and 17 show the efficiency (left) and the cross section upper limit (right) on the T1tttt

simplified model for these two analyses. The selection yielding the best expected limit for each

analysis is shown in Figure 18. These results are corrected for the signal contamination in the

control region used in the data driven methods. The SS dilepton analysis is sensitive only to

so-called “prompt-prompt leptons” (leptons from W-boson decay). The background estimation

method correctly maps the signal events in the control region to the signal events in the signal

region. The final correction is verified to be small.

The ET +b-jets analysis suffers from signal contamination in the low ET sideband control region.

This reduces the cross section limit by a factor of 2–3 in the low mass region.

The summary plot in Figure 19 compares the cross section upper limit of the ET +b and the SS

dilepton analyses with the reference cross section. The cross section upper limits are reported

as a function of the gluino mass for a fixed LSP mass of 50 GeV. The ET +b analysis cannot

yet exclude gluino pair production, while the SS dilepton analyses, which is typically a factor

of 4-5 more sensitive, can exclude a gluino mass below 700 GeV. The comparison of the cross

section upper limits shows that the SS dilepton analysis is more sensitive to the low mass region


4.7 Multileptons 15

LSP mass [GeV]

~ ~ ~

± ± ± 0 ~ ~

pp → g g,

g → q q


χ ,


χ → l ν


χ ; m( q)>

> m( g)

1200

CMS Preliminary

1000

­1

s = 7 TeV, ∫ Ldt=4.98 fb

SS e/ µ

∼±

m( χ

LSP mass [GeV]

HighPT H ≥ 80, E ≥ 120

T T

HighPT H ≥ 200, E ≥ 120

T

800

T

HighPT H ≥ 450, E ≥ 120

T T

LowPT H ≥ 200, E ≥ 120

T T

600

400

200

Most sensitive selection

400 600 800 1000 1200

gluino mass [GeV]

∼0

~

) = 0.5 m( χ ) + 0.5 m( g)

g )

1200

CMS Preliminary

~

± ± ± 0

pp →

~

g

~

g,

~

g → q q


χ ,


χ → l ν


χ ; m(

~

q)>

> m(

1000

800

600

400

200

s = 7 TeV,


400 600 800 1000 1200

gluino mass [GeV]

0

χ ) + 0.5 m(

~

g)


±

χ ) = 0.5 m(


m(

­1

Ldt=4.98 fb

SS e/ µ , HighPT H ≥ 80, E ≥ 120

T T

0.12

0.1

0.08

0.06

0.04

0.02

0

ε

×

A

LSP mass [GeV]

g )

1200

CMS Preliminary

~

± ± ± 0

pp →

~

g

~

g,

~

g → q q


χ ,


χ → l ν


χ ; m(

~

q)>

> m(

1000

800

600

400

200

s = 7 TeV,

SS e/ µ


400 600 800 1000 1200

gluino mass [GeV]

0

χ ) + 0.5 m(

~

g)


±

χ ) = 0.5 m(


m(

σ

NLO­QCD

NLO­QCD

1/3 × σ

NLO­QCD

­1

Ldt=4.98 fb

Figure 12: SS dileptons: Best selection (top left), selection efficiency for the “HighPT HT ≥

80, HT ≥ 120” selection (top right), and cross section upper limit for the best selection (bottom),

for the T5lnu topology, as a function of gluino and LSP mass, with the chargino mass set using

x = 1

2 .

because of the relaxed HT and ET requirement; at high gluino mass, the fully hadronic analysis

is comparable.

The SS+b analysis [13] with the 4.98 fb −1 of integrated luminosity sets a cross section upper

limit as shown in Figure 20. At low masses, the cross section upper limit is a factor 10 lower

than the old SS analysis with lower luminosity (compare to Figure 17). When the cross section

upper limit is compared to the reference cross section, the range of excluded gluino mass moves

only from 700 to 800 GeV due to the rapidly decreasing cross section. In Figure 20 the efficiency

is also reported.

4.7 Multileptons

A multi-channel search based on events containing at least three charged leptons has also been

performed [11], and can be used to set limits on the TChi topologies.

The topology TChiSlepSlep is characterized by chargino-neutralino production, followed by

3 × σ

1

­1

10

­2

10

)

s

[pb] (CL

σ

95% CL upper limit on


16 4 Results with Simplified Models

LSP mass [GeV]

g )

1200

0.4

CMS Preliminary

~

0

0 0 + ­ 0

pp →

~

g

~

g,

~

g → q q


χ ,

~

g → q q


χ ,


χ → l l


χ ; m(

~

q)>

> m(

2 2

1000

800

600

400

200

s = 7 TeV,

OS e/ µ

edge


­1

Ldt=4.98 fb

400 600 800 1000

gluino mass [GeV]

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

χ ) + 0.5 m(

~

g)


0

χ ) = 0.5 m(

2


m(

g )

1200

0.4

CMS Preliminary

~

0

0 0 + ­ 0

pp →

~

g

~

g,

~

g → q q


χ ,

~

g → q q


χ ,


χ → l l


χ ; m(

~

q)>

> m(

2 2

LSP mass [GeV]

1000

800

600

400

200

s = 7 TeV,

OS e/ µ + E

T


400 600 800 1000

gluino mass [GeV]

0

χ ) + 0.5 m(

~

g)


0

χ ) = 0.5 m(

2


m(

­1

Ldt=4.98 fb

0

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

ε

×

A

ε

×

A

LSP mass [GeV]

LSP mass [GeV]

g )

1200

CMS Preliminary

~

0

0 0 + ­ 0

pp →

~

g

~

g,

~

g → q q


χ ,

~

g → q q


χ ,


χ → l l


χ ; m(

~

q)>

> m(

2 2

1000

800

600

400

200

1000

800

600

400

200

s = 7 TeV,

OS e/ µ

σ

edge

NLO­QCD


NLO­QCD

1/3 × σ

NLO­QCD

3 × σ

­1

Ldt=4.98 fb

400 600 800 1000

gluino mass [GeV]

0

χ ) + 0.5 m(

~

g)


0

χ ) = 0.5 m(

2


m(

g )

1200

CMS Preliminary

~

0

0 0 + ­ 0

pp →

~

g

~

g,

~

g → q q


χ ,

~

g → q q


χ ,


χ → l l


χ ; m(

~

q)>

> m(

2 2

s = 7 TeV,

OS e/ µ +

E


T

NLO­QCD

400 600 800 1000

gluino mass [GeV]

0

χ ) + 0.5 m(

~

g)


0

χ ) = 0.5 m(

2


m(

σ

NLO­QCD

1/3 × σ

NLO­QCD

­1

Ldt=4.98 fb

Figure 13: OS dileptons: Efficiency and cross section upper limit for the topology T3lh from

edge reconstruction (top), and from the ET and HT selection (bottom). Results are shown as a

function of gluino and LSP mass, with the chargino mass set using x = 1

2 .

decays through sleptons, yielding 3 charged leptons in the final state. None of the leptons

come directly from a Z boson decay. The signal selection efficiency of the 3–4 leptons analysis

is shown in Figure 21 (left, top) and increases for higher chargino and neutralino masses, and

is low where the mass splitting between the heavier gauginos and LSP is small and leptons

are produced with lower transverse momentum. The cross section upper limit and exclusion

contours are shown in Figure 21 (right, top). All the exclusive channels that characterize this

multilepton analysis contribute to the signal efficiency. In Figure 21 (bottom), the cross section

upper limit is shown for a massless LSP as a function of the degenerate chargino and neutralino

mass. The most significant channel in this topology is characterized by: 3 charged leptons but

no tau leptons, no ℓ + ℓ − masses in the Z boson window, low-HT, and high-ET.

The TChiwz topology, instead, explores the same production process as TChiSlepSlep, but with

decays to W and Z bosons. In Figure 22 (top), the efficiency (left) and the cross section upper

limit for a massless LSP (right) is reported as function of the degenerate chargino and neutralino

mass.

3 × σ

1

­1

10

10

1

10

)

s

[pb] (CL

­2

­1

10

σ

95% CL upper limit on

)

s

[pb] (CL

­2

σ

95% CL upper limit on


[GeV]

LSP

m

[GeV]

LSP

m

1200

1000

800

600

400

200

1200

1000

800

600

400

200

pp →

~

g

~

g,

~

g → 2b + LSP; m(

~

q)>>m(

~

g)

Lint

= 1.1 fb s = 7 TeV

CMS Preliminary

2L

2L 2L

2L 2L

2L

2L

2L

2L

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400 600 800 1000 1200

m~

[GeV]

pp →

~

g

~

g,

~

g → 2b + LSP; m(

~

q)>>m(

~

g)

-1

,

Lint

= 1.1 fb s = 7 TeV

CMS Preliminary

3 7 11 16 19 20 25 30 34 37 39 40

3 6 11 15 19 19 24 29 32 35 38 39 41

3 6 11 15 18 17 23 28 31 34 37 38 40 40

3 5 9 13 18 17 21 26 30 32 36 37 38 40 41

2 5 9 13 16 19 19 24 28 31 34 35 37 39 40 41

2 4 7 11 15 18 16 21 25 29 32 34 37 37 39 40 40

1 3 6 10 13 16 14 18 23 26 29 32 34 36 37 38 39 38

g

3 8

3 7 13

3 7 13 18

3 7 13 18 18

3 7 13 17 17 24

3 7 12 18 17 23 29

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3 7 12 16 15 20 26 31 34 37 40

2L

2L

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1T

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0

400 600 800 1000 1200

m~

[GeV] g

2 4 8 11 14 17 15 19 23 26 29 32 33 35 37 37 38 38

3

2L

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40

35

30

25

20

15

10

5

[%]

ε

×

A

[GeV]

LSP

m

1200

1000

800

600

400

200

pp →

~

g

~

g,

~

g → 2b + LSP; m(

~

q)>>m(

~

g)

-1

,

Lint

= 1.1 fb s = 7 TeV

CMS Preliminary

prod

σ = σNLO-QCD

prod NLO-QCD

σ = 3 × σ

prod

NLO-QCD

σ = 1/3 × σ

0.61 0.23

0.56 0.23 0.13

0.56 0.23 0.13 0.10

0.51 0.24 0.13 0.10 0.06

0.60 0.26 0.13 0.10 0.08 0.05

0.58 0.26 0.15 0.10 0.07 0.05 0.04

0.56 0.23 0.14 0.10 0.07 0.05 0.04 0.03

0.55 0.25 0.14 0.11 0.07 0.06 0.04 0.03 0.03

0.58 0.28 0.15 0.10 0.07 0.05 0.04 0.03 0.03 0.03

0.52 0.27 0.15 0.11 0.08 0.06 0.04 0.04 0.03 0.03 0.03

0.60 0.28 0.17 0.11 0.09 0.06 0.04 0.04 0.03 0.03 0.03 0.03

0.64 0.31 0.16 0.12 0.09 0.06 0.05 0.04 0.04 0.03 0.03 0.03 0.03

0.68 0.31 0.17 0.12 0.09 0.07 0.05 0.04 0.04 0.03 0.03 0.03 0.03 0.03

0.71 0.35 0.20 0.13 0.10 0.07 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03

0.86 0.41 0.21 0.14 0.11 0.09 0.06 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03

1.33 0.47 0.26 0.16 0.12 0.10 0.07 0.05 0.05 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.03

1.72 0.72 0.33 0.20 0.13 0.11 0.08 0.06 0.05 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03

10

-1

10

10

400 600 800 1000 1200

m~

[GeV] g

1.03 0.48 0.24 0.16 0.12 0.10 0.08 0.06 0.05 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03

Figure 14: ET +b: Selection with best expected limit, where 1T and 2L correspond to the ≥1

tight b-tag and ≥ 2 loose b-tag selections (top); the selection efficiency (bottom left) and cross

section upper limit (bottom right) on the T1bbbb simplified model, as a function of gluino and

LSP mass.

The topology TChizz produces a signature of two Z bosons and ET. The efficiency (left) and the

cross section upper limit (right) is represented in Figure 22 (bottom). The multilepton analysis

in this topology has a stronger upper limit with respect to TChiwz, because of the reduced

backgrounds for a final state with 4 leptons. In both TChizz and TChiwz, the efficiency has been

normalized to the inclusive W and Z boson lepton yield. This is not necessary for TChiSlepSlep,

which is biased by construction to yield leptons in the final state.

5 Conclusions

The results of several CMS analyses searching for SUSY have been summarized and re-interpreted

in terms of simplified models. Results are shown in terms of signal selection efficiency times

acceptance and cross section upper limits.

For many of the searches, the upper limit on cross section times branching ratios depends

strongly on the masses of the particles involved, particularly the mass splitting between the

mother and the LSP. The amount of visible energy is reduced when the mass splitting decreases

0.57

1

-2

Cross section UL at 95% CL [pb]

17


18 5 Conclusions

(GeV)

LSP

m

pp →

~

g

~

g,

~

g → 2b + LSP; m(

~

q)>>m(

~

g)

1200 0.5ε

1000

800

600

400

200

CMS Preliminary

-1

s = 7 TeV L=1.1 fb

lowMT2

400 600 800 1000 1200

m~

(GeV) g

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

×

A

(GeV)

LSP

m

pp →

~

g

~

g,

~

g → 2b + LSP; m(

~

q)>>m(

~

g)

1200 )

1000

800

600

400

200

CMS Preliminary

-1

s = 7 TeV L=1.1 fb

lowMT2

prod

σ = σ

prod

σ = 3 × σ

prod

σ = 1/3 × σ

NLO-QCD

NLO-QCD

NLO-QCD

400 600 800 1000 1200

m~

(GeV) g

Figure 15: M T,2b: selection efficiency (left) and cross section upper limit (right) for events with

at least one b-jet on the T1bbbb simplified model, as a function of gluino and LSP mass.

(GeV)

0

χ

m

~

pp →

~

g

~

g,

~

g → 2t + LSP; m( t)>>m(

~

g)

1200 0.2ε

1000

800

600

400

200

CMS Preliminary

-1

s = 7 TeV L=1.1 fb

ET

+ b : OR all selection

400 600 800 1000 1200

m~

(GeV) g

0.18

0.16

0.14

0.12

0.1

0.08

0.06

0.04

0.02

0

×

A

(GeV)

0

χ

m

~

pp →

~

g

~

g,

~

g → 2t + LSP; m( t)>>m(

~

g)

1000

800

600

400

200

400 600 800 1000 1200

m~

(GeV) g

10

1

-1

10

-2

10

s

(pb) (CL

σ

95% CL upper limit on

1200 )

CMS Preliminary

-1

s = 7 TeV L=1.1 fb

ET

+ b : OR all selection

prod NLO-QCD

σ = σ

prod

NLO-QCD

σ = 3 × σ

prod

NLO-QCD

σ = 1/3 × σ

Figure 16: ET +b: efficiency (left) and cross section upper limit (right) on the T1tttt simplified

model, as a function of gluino and LSP mass.

or when a decay to an intermediate particle is allowed. In both cases, the reduced visible energy

decreases the selection efficiency, and the upper limit increases.

The 95% CL exclusion contours compare the results of each topology with a reference cross section.

The sensitivity is determined by the compensating effects of increasing signal efficiency

and decreasing cross section as the mother mass increases. Figures 23 and 24 summarize the

excluded gluino or squark masses for the hadronic and leptonic topologies investigated, respectively,

for a small LSP mass ≈ 0 GeV and for a reference point defined by a mass splitting

between the mother and the LSP of m g − 200 GeV. Figure 25 shows the results for the analysis

with the best exclusion limits for each topology.

First, these results are reviewed in terms of final states. For the all hadronic analyses, αT is most

sensitive in the T2 topology, which should be most two-jet-like. αT and HT +jets are comparable

10

1

-1

10

-2

10

s

(pb) (CL

σ

95% CL upper limit on


(GeV)

0

χ

m

~

pp →

~

g

~

g,

~

g → 2t + LSP; m( t)>>m(

~

g)

1200 0.04 ε

1000

800

600

400

200

CMS Preliminary

-1

s = 7 TeV L=0.98 fb

SS : OR all selection

400 600 800 1000 1200

m~

(GeV) g

0.03

0.02

0.01

0

×

0.035

A

0.025

0.015

0.005

(GeV)

0

χ

m

~

pp →

~

g

~

g,

~

g → 2t + LSP; m( t)>>m(

~

g)

1200 )

1000

800

600

400

200

CMS Preliminary

-1

s = 7 TeV L=0.98 fb

SS : OR all selection

prod NLO-QCD

σ = σ

prod

σ = 3 × σ

prod

σ = 1/3 × σ

NLO-QCD

NLO-QCD

400 600 800 1000 1200

m~

(GeV) g

Figure 17: SS dilepton: efficiency (left) and the cross section upper limit (right) on the T1tttt

simplified model, as a function of gluino and LSP mass.

(GeV)

0

χ

m

~

pp →

~

g

~

g,

~

g → 2t + LSP; m( t)>>m(

~

g)

1200

1000

800

600

400

200

CMS Preliminary

-1

s = 7 TeV L=0.98 fb

1=HT

> 400, ET

> 120

2=HT

> 400, ET

> 50

3=H > 200, ET

> 120

T

400 600 800 1000 1200

m~

(GeV) g

3

2

1

best selection

(GeV)

0

χ

m

~

pp →

~

g

~

g,

~

g → 2t + LSP; m( t)>>m(

~

g)

1200

1000

800

600

400

200

CMS Preliminary

-1

s = 7 TeV L=1.1 fb

ET

+ b : OR all selection

1= ≥ 1b L

2= ≥1b

T

3= ≥2b

L

4= ≥2b

T

400 600 800 1000 1200

m~

(GeV) g

Figure 18: Selection that gives the best expected upper limit for the SS dilepton (left) and the

ET +b (right) analyses on the T1tttt simplified model, as a function of gluino and LSP mass.

for the multijet topology T1, likely due to the ET requirement. HT +jets is more sensitive than

αT in the T5zz topology, which contains longer decay chains and renders the event shape more

spherical.

For the b-tagged analyses, ET +b and MT,2b have comparable sensitivity, except for smaller

mass splitting, where ET +b is more sensitive.

For Z boson leptonic analyses, the Z+ET analysis has more sensitivity than JZB, though the JZB

cross section limits are nearly vertical lines in the (mother, LSP) plane, and are generally more

sensitive to the smallest mass splittings.

For the off-Z leptonic analyses, SS and OS dilepton searches are comparable, with the SS dilepton

analysis having good sensitivity to the T1tttt topology.

10

1

-1

10

-2

10

4

3

2

1

s

(pb) (CL

σ

95% CL upper limit on

best selection

19


20 5 Conclusions

x BR (pb)

σ

95% CL upper limit on

2

10

10

1

-1

10

-2

10

-3

~

pp →

~

g

~

g,

~

g → 2t + LSP; m( t)>>m(

~

g)

CMS Preliminary

s = 7 TeV

m(LSP) = 50 (GeV)

σ

~ ~

NLO ( gg)

(Prospino)

-1

ET

+ b (1.1 fb )

-1

SS e/ µ (0.98 fb )

10

450 500 550 600 650 700 750 800

m~

(GeV)

Figure 19: Cross section upper limit on the topology T1tttt for the ET +b and SS analyses as a

function of gluino mass and for a fixed LSP mass of 50 GeV.

LSP mass [GeV]

g )

~

0

pp →

~

g

~

g,

~

g → t t


χ ; m(

~

q)>

> m(

800 CMS Preliminary

700

600

500

400

300

200

100

s = 7 TeV,

SS+b


­1

Ldt=4.98 fb

600 800 1000

gluino mass [GeV]

0.02

0.018

0.016

0.014

0.012

0.01

0.008

0.006

0.004

0.002

0

ε

×

A

LSP mass [GeV]

700

600

500

400

300

200

100

g

g )

~

0

pp →

~

g

~

g,

~

g → t t


χ ; m(

~

q)>

> m(

800 CMS Preliminary

s = 7 TeV,

SS+b

σ

NLO­QCD


NLO­QCD

1/3 × σ

NLO­QCD

­1

Ldt=4.98 fb

600 800 1000

gluino mass [GeV]

Figure 20: SS+b: Efficeincy and cross section upper limit on the topology T1tttt as a function of

gluino and LSP mass.

For T1tttt, SS+b is more sensitive than the untagged SS analysis, yielding exclusions that are

50-100 GeV more stringent.

Secondly, the results are reviewed in terms of the mass splitting between the mother and LSP.

For m χ 0 = 0 GeV, the all hadronic and non-Z dilepton analyses are most sensitive. For a more

compressed mass spectrum, m mother − m χ 0 = 200 GeV, the SS dilepton and the OS dilepton and

ET +b analyses perform the best.

Looking at all analyses, we conclude that the least stringent limits are in the range of 400 − 550

GeV, while the most stringent are in the range of 650 − 900 GeV.

3 × σ

1

­1

10

­2

10

)

s

[pb] (CL

σ

95% CL upper limit on


LSP mass [GeV]

0

χ )

2

450

CMS Preliminary

400

­1

s = 7 TeV, ∫ Ldt=4.98 fb

350

multilepton ( ≥ 3)

∼ ±

χ ),m(


0 ±

0 0

pp →


χ


χ → l l l ν


χ


χ ; m(

~

g),m(

~

q)>

> m(

2

300

250

200

150

100

50

0

100 200 300 400

chargino/heavy neutralino mass [GeV]

0

χ )


0

χ ) + 0.5 m(

2

∼ ±

χ |

∼ ~

m( l)

= 0.5 m(

[fb]

σ

95% CL upper limit on

10

3

10

10

4

2

10

pp →

χ ∼

0

2

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0 χ )


χ± ),m(


0 0

χ± → lll ν χ χ ; m(

~

g),m(

~

q)>>m(


CMS Preliminary

-1

s = 7 TeV ∫ L dt = 4.98 fb

σNLO

σNLO

100 200 300 400 500

chargino/heavy neutralino mass [GeV]

0

χ± ) (wino)

∼ 0 χ

2


(

χ± ) (Higgsino)

∼ 0 χ ∼

(

2

multilepton( ≥3)

m(LSP) = 0 [GeV]

~

± 0 ∼0

m( l)=0.5

m(


χ |


χ ) + 0.5 m( χ )

2

2

ε

×

A

LSP mass [GeV]

0

χ )

2

450

CMS Preliminary

400

­1

s = 7 TeV, ∫ Ldt=4.98 fb

350

multilepton ( ≥ 3)

300

∼ ±

χ ),m(


0 ±

0 0

pp →


χ


χ → l l l ν


χ


χ ; m(

~

g),m(

~

q)>

> m(

2

NLO­QCD

σ

NLO­QCD

1/3 × σ

NLO­QCD

3 × σ

250

200

150

100

50

0

100 200 300 400

chargino/heavy neutralino mass [GeV]

0

χ )


0

χ ) + 0.5 m(

2

∼ ±

χ |

∼ ~

m( l)

= 0.5 m(

Figure 21: Multileptons and TChiSlepSlep: selection efficiency (left, top); cross section upper

limit as function of chargino and LSP mass (right, top) and for a fixed LSP mass (bottom)

Figure 26 compares all the exclusion contours in the gluino–LSP mass plane obtained by different

analyses for similar topologies. This aids in identifying potential blind spots and understanding

the complementarity and overlap of various analyses. Figure 26 (left) shows the

coverage of the fully hadronic analyses on gluino pair production. The fully hadronic analyses

HT +jets and αT perform poorly for compressed spectra. However, due to double b-tagging and

the relaxed HT and ET requirement, the ET +b analysis is more sensitive to compressed spectra.

A similar behavior occurs in the SS and OS dilepton analyses (see Figures 12 and 13). In that

case, the addition of edge identification yields a better reach than a generic OS + ET search.

Figure 26 (right) compares the excluded mass regions of the fully hadronic analyses with the

JZB and ET +Z dilepton analysis for the T5zz topology. For this comparison, the 1.1 fb −1

results are used for the dilepton analyses. The complementarity between the fully hadronic

and dilepton analysis is evident. The HT +jets fully hadronic analysis covers the region of large

gluino mass, while the ET +Z dilepton analysis covers the region of lower mass splitting.

In conclusion, the simplified model approach allows a comparison of the various CMS searches

for Supersymmetry for a range of mass parameters that is beyond that of the cMSSM. The

tabulation of signal efficiency and upper limits on signal cross section for various simplified

model topologies can be used to set limits on theoretical models not considered directly by the

analyses.

10

3

2

10

)

s

[fb] (CL

σ

95% CL upper limit on

21


22 A Technical Details of Monte Carlo Event Generation for SMSes

LSP mass [GeV]

LSP mass [GeV]

0

χ )

2

∼ ±

χ ),m(


± 0

0 0

pp →


χ


χ → W Z


χ


χ ; m(

~

g),m(

~

q)>

> m(

2

400

300

200

100

CMS Preliminary

s = 7 TeV, ∫

multilepton ( ≥ 3)

­1

Ldt=4.98 fb

0

100 200 300 400

gluino mass [GeV]

0

χ )

3

∼ 0

χ ),m(

2


0 0

0 0

pp →


χ


χ → Z Z


χ


χ ; m(

~

g),m(

~

q)>

> m(

3 2

400

300

200

100

CMS Preliminary

s = 7 TeV, ∫

multilepton ( ≥ 3)

­1

Ldt=4.98 fb

0

100 200 300 400

gluino mass [GeV]

0.012

0.01

0.008

0.006

0.004

0.002

0

0.012

0.01

0.008

0.006

0.004

0.002

0

ε

×

A

ε

×

A

[fb]

σ

95% CL upper limit on

[fb]

σ

95% CL upper limit on

10

5

10

4

10

10

6

3

2

10

10

5

10

4

10

10

2

10

0 χ )


χ± ),m(


0

χ± → WZ + χ ; m(

~

g),m(

~

q)>>m(

∼ 0 χ ∼

pp →

CMS Preliminary

-1

s = 7 TeV ∫ L dt = 4.98 fb

σNLO

σNLO

χ± ) (wino)

∼ 0 χ

2


(

χ± ) (Higgsino)

∼ 0 χ ∼

(

100 200 300 400 500

chargino/heavy neutralino mass [GeV]

6

3

3

2

1

2

multilepton( ≥3)

2

m(LSP) = 0 [GeV]

0 χ )


χ± ),m(


0

0

χ → ZZ + χ ; m(

~

g),m(

~

q)>>m(

∼ 0 χ ∼

pp →

CMS Preliminary

-1

s = 7 TeV ∫ L dt = 4.98 fb

σNLO

0 χ ) (higgsino)

∼ 0 χ ∼

(

2 3

multilepton( ≥3)

m(LSP) = 0 [GeV]

150 200 250 300

heavy neutralino mass [GeV]

Figure 22: Multileptons and TChiwz and TChizz: Signal selection efficiency (left) and cross

section upper limit (right) for TChiwz (top) and TChizz (bottom). The selection efficiency is

shown as a function of chargino or heavy neutralino mass and LSP mass. The upper limit is

shown as a function of chargino or heavy neutralino mass for a massless LSP.

A Technical Details of Monte Carlo Event Generation for SMSes

The simplified models are simulated using a particular production and decay model, and normalized

using reference cross sections. The normalization is important for the interpretation of

results based on the simulated model samples.

A.0.1 Production and decay modeling

The simplified models are simulated using PYTHIA 6.426 [33] with Tune Z2, together with a

parametrized simulation of the CMS detector called “Fastsim” [36]. Reference cross sections for

SUSY processes are calculated at next to leading order (NLO) precision using PROSPINO [37]

and CTEQ6 parton distribution functions [38].

The production of the the primary particles in each SMS is modeled with SUSY processes as

implemented in PYTHIA in the limit that extraneous particles are decoupled. A constant matrix

element is used for all two and three body decays. This choice would allow us to efficiently

reweight the decay distribution to a more complicated one if the need arose.

The external decay packages TAUOLA and EVTGEN are not used directly; some analyses ac-

2


CMS Preliminary

T1: ˜g →qq˜χ 0

T1: ˜g →qq˜χ 0

T1bbbb: ˜g →bb˜χ 0

T1bbbb: ˜g →bb˜χ 0

T2: ˜q →q˜χ 0

T2: ˜q →q˜χ 0

T5zz: ˜g →qq˜χ 0 2

T5zz: ˜g →qq˜χ 0 2

m(mother)−m(˜χ 0 ) =200 GeV

α T, 1.1 fb −1 , gluino

E T + jets, 1.1 fb −1 , gluino

E T +b, 1.1 fb −1 , gluino

MT2, 1.1 fb −1 , gluino

α T, 1.1 fb −1 , squark

E T + jets, 1.1 fb −1 , squark

E T + jets, 1.1 fb −1 , gluino

m(˜χ 0 )=0 GeV

αT, 1.1 fb

0 200 400 600 800

Mass scales [GeV]

1000

−1 , gluino

Figure 23: Exclusion limits for gluino and squark masses, for m χ 0 = 0 GeV (dark blue) and

m mother − m χ 0 = 200 GeV (light blue), for each analysis, for the hadronic results. For limits on

m(g), m(q) ≫ m(g), and vice versa. σ prod = σ NLO−QCD . If not specified otherwise, x = 0.5 for

intermediate mass states.

count for the impact of this choice. To effectively produce model scans within the CMS computing

infrastructure, PYTHIA is first used to produce Les Houches Event (LHE) files, which

are then processed in another PYTHIA run to make realistic events. This is described more later.

The mass spectrum and decay modes of the particles in a specific model are fixed using SUSY-

Les Houches Accord (SLHA) input files. A typical SLHA file from the CMS cMSSM scans,

produced using SOFTSUSY3.1.6 and SUSY-HIT 1.2, is modified on a model-by-model basis.

Examples are provided below.

The SMS T1 is based on gluino pair (gg production), with all the squarks set to be very heavy

(technically, at least 100 TeV). In this limit, the squarks decouple, and the production rate and

kinematics is determined by QCD gauge invariance. The gluino pair production process q ¯q →

gg and gg → gg are selected using MSUB(243)=1 and MSUB(244)=1. 3 For the simplest T1,

the free parameters are the gluino mass m g and the lightest neutralino mass m χ 0. The 3-body

decays of the g → q ¯q χ 0 are handled in the SLHA file. An example is provided in the Appendix.

For T2 (qq ∗ production), the gluino, sbottoms and stops are taken to be very heavy. Again, in

this limit, the production rate and kinematics are set by gauge invariance. The squark anti-

3 In all cases, these are generated with the LO fraction of gg → X versus q ¯q → X. For the final results, the entire

sample is normalized to the Prospino NLO cross section.

23


24 A Technical Details of Monte Carlo Event Generation for SMSes

CMS Preliminary

T1tttt: ˜g →tt˜χ 0 1

T3w: ˜g →qq(W)˜χ 0

T3Lh: ˜g →qq˜χ 0 |˜χ 0 2

T3Lh: ˜g →qq˜χ 0 |˜χ 0 2

T5zz: ˜g →qq˜χ 0 2

T5zz: ˜g →qq˜χ 0 2

T5Lnu: ˜g →qq˜χ ±

TChiSlep: ˜χ 0 2 ,˜χ ± →lll˜χ 0 ˜χ 0

m(mother)−m(˜χ 0 ) =200 GeV

SS+b, 4.98 fb −1 , gluino

e/µ spectrum, 4.98 fb −1 , gluino

l ± l ∓ edge, 4.98 fb −1 , gluino

l ± l ∓ + E T, 4.98 fb −1 , gluino

Z +E T, 4.98 fb −1 , gluino

JZB, 4.98 fb −1 , gluino

l ± l ± , 4.98 fb −1 , gluino

x =0.25

x =0.5

x =0.75

m(˜χ 0 )=0 GeV

multilepton, 4.98 fb

0 200 400 600 800

Mass scales [GeV]

1000

−1 , neutralino/chargino

Figure 24: Exclusion limits for gluino and squark masses, for m χ 0 = 0 GeV (dark blue) and

m mother − m χ 0 = 200 GeV (light blue), for each analysis, for the leptonic results. For limits on

m(g), m(q) ≫ m(g), and vice versa. σ prod = σ NLO−QCD . If not specified otherwise, x = 0.5 for

intermediate mass states. For T3w and T5zz, results for all three values of x are presented.

squark production processes fi ¯ fj → qLiq ∗ Lj , fi ¯ fi → qLjq ∗ Lj , and gg → qLiq ∗ Li are selected using

MSUB(274)=1, MSUB(277)=1, and MSUB(279)=1. The 2-body decays of the q → q χ 0 are handled

in the SLHA file.

qq production is not part of our simplified models, even though it is often the dominant process

in the cMSSM at low m0. The reason is that the production rate depends upon the gluino mass.

Furthermore, the kinematics (rapidity and pT) of the squarks are not too dissimilar from qq ∗

production; in fact, the acceptance for qq production is expected to be higher. Thus, limits from

T2 can be conservatively applied to qq production with similar decays.

When dealing with pairs of Majorana particles (the gluino and the neutralinos), some SMS

require one particle to decay one way, and the other to decay another way for every event. This

is handled using the Pythia MDME codes.


CMS Preliminary

T1: ˜g →qq˜χ 0

T1tttt: ˜g →tt˜χ 0 1

T2: ˜q →q˜χ 0

T3w: ˜g →qq(W)˜χ 0

T3Lh: ˜g →qq˜χ 0 2 |˜χ 0

T5zz: ˜g →qq˜χ 0 2

T5Lnu: ˜g →qq˜χ ±

TChiSlep: ˜χ 0 2 ,˜χ ± →lll˜χ 0 ˜χ 0

m(mother)−m(˜χ 0 ) =200 GeV

1.1 fb −1 , gluino

4.98 fb −1 , gluino

1.1 fb −1 , squark

4.98 fb −1 , gluino

4.98 fb −1 , gluino

4.98 fb −1 , gluino

4.98 fb −1 , gluino

x =0.25

x =0.5

x =0.75

m(˜χ 0 )=0 GeV

4.98 fb

0 200 400 600 800

Mass scales [GeV]

1000

−1 , neutralino/chargino

Figure 25: Best exclusion limits for gluino and squark masses, for m χ 0 = 0 GeV (dark blue)

and m mother − m χ 0 = 200 GeV (light blue), for each topology, for all results. For limits on

m(g), m(q) ≫ m(g), and vice versa. σ prod = σ NLO−QCD . If not specified otherwise, x = 0.5

for intermediate mass states. For T3w and T5zz, results for all three values of x are presented.

95% exclusion limits for g

~

g

~

, g

~

→ bb


χ

(GeV)

0

χ ∼

m

1200

1000

800

600

400

200

MT2 + b

ET

+ b

αT

ET

0

[

~

g→qq


χ ]

0

+ jets [

~

g→qq


χ ]

CMS Preliminary

-1

s = 7 TeV L=1.1 fb

ISR uncertainties

300 400 500 600 700 800 900 1000 1100 1200

0

m

~

g

(GeV)

(GeV)

0

χ ∼

m

95% exclusion limits for g

~

g

~

, g

~

→ qqZ


χ

1200

1000

800

600

400

200

Z + ET

JZB

αT

-1

0.98 fb

-1

2.1 fb

-1

1.1 fb

ET

+ jets

-1

1.1 fb

CMS Preliminary

s = 7 TeV

ISR uncertainties

200 400 600 800 1000 1200

Figure 26: Exclusion contours for several analyses: (left) T1bbbb/T1; (right) T5zz.

0

m

~

g

(GeV)

As mentioned earlier, events are not generated in one step. First, the PYUPEV subroutine is

used to generate the hard production and resonance decays and write these events to LHE

files. Pythia defines a resonance as any parton heavier than a b quark, so all SUSY particles

25


26 A Technical Details of Monte Carlo Event Generation for SMSes

(except for the LSP) and all gauge or Higgs bosons or top quarks are decayed. A comment tag

is added to each event to identify the model. Groups of LHE files are then combined into larger

LHE files, which are staged to a mass storage system for later, efficient event generation using

the LHE interface to Pythia. Another advantage of this method is that filtering can be applied

on LHE files before combination so that, for example, at least one hard lepton is present before

parton showering, hadronization, etc.

A.0.2 Configuration Details

The basic Pythia configuration file should always contain the following piece:

"MSEL=0", ! User selects all processes

"IMSS(1)=11", ! Spectrum/decays set from SLHA file

...

’IMSS(21) = 33 ! LUN number for SLHA File (must be 33) ’,

’IMSS(22) = 33 ! Read-in SLHA decay table ’

The mass spectrum for simplified models is set in the following portion of the SLHA file:

#

BLOCK MASS # Mass Spectrum

# PDG code mass particle

25 125.00

35 1.00000000E+03

36 1.00000000E+03

37 1.00000000E+03

1000001 MSQUARK # ˜d_L

2000001 1.00000000E+05 # ˜d_R

1000002 MSQUARK # ˜u_L

2000002 1.00000000E+05 # ˜u_R

1000003 MSQUARK # ˜s_L

2000003 1.00000000E+05 # ˜s_R

1000004 MSQUARK # ˜c_L

2000004 1.00000000E+05 # ˜c_R

1000005 MSBOT # ˜b_1

2000005 1.10000000E+05 # ˜b_2

1000006 MSTOP # ˜t_1

2000006 1.10000000E+05 # ˜t_2

1000011 1.00000000E+05 # ˜e_L

2000011 1.00000000E+05 # ˜e_R

1000012 1.00000000E+05 # ˜nu_eL

1000013 1.00000000E+05 # ˜mu_L

2000013 1.00000000E+05 # ˜mu_R

1000014 1.00000000E+05 # ˜nu_muL

1000015 1.00000000E+05 # ˜tau_1

2000015 1.00000000E+05 # ˜tau_2

1000016 1.00000000E+05 # ˜nu_tauL

1000021 MGLUINO # ˜g

1000022 MCHI01 # ˜chi_10

1000023 MCHI02 # ˜chi_20

1000024 MCHIP1 # ˜chi_1+

1000025 MCHI03 # ˜chi_30

1000035 1.00000000E+05 # ˜chi_40

1000037 1.00000000E+05 # ˜chi_2+

#


The specific masses of the ũL, ˜

dL, ˜cL,˜sL squarks, lightest bottom squark, lightest top squark,

gluino, lightest neutralino, 2nd neutralino, 3rd neutralino, and lightest chargino have been replaced

by the keywords MSQUARK, MSBOT, MSTOP, MGLUINO, MCHI01, MCHI02, MCHI03,

MCHIP1. These are replaced with numerical values for a particular model.

Decays are treated with the following format for 3-body decays: 4

# PDG Width

DECAY 1000021 1.00000000E+00 # chargino1+ decays

# BR NDA ID1 ID2 ID3

0.50000000E+00 3 1000022 -1 1 # BR(˜gl -> N1 dbar d)

0.50000000E+00 3 1000022 -2 2 # BR(˜gl -> N1 ubar u)

Additionally, the parameter choice MSTP(47)=0 ensures that the decay kinematics are determined

using a flat matrix element. For strongly interacting particle, a total width of 1 GeV is

used; for weakly interacting particles, a width of 0.1 GeV is used.

Two-body decays are treated with the format:

# PDG Width

DECAY 1000001 1.00000000E+00 # sdown_L decays

# BR NDA ID1 ID2

1.00000000E+00 2 1000022 1 # BR(˜d_L -> ˜chi_10 d)

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29

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