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dΣdp,j1 fbGeV dΣdRj2,lfb 0.02 0.01 0.005 0.002 0.001 510 4 1.0 0.8 0.6 0.4 0.2 LO NLO 0 200 400 600 800 p , j1 GeV LO NLO 0.0 0 1 2 3 4 5 6 Rj2,l dΣdp,j2 fbGeV 0.020 0.010 0.005 0.002 0.001 2.0 1.5 1.0 0.5 LO NLO 0 100 200 300 400 p,j2 GeV LO NLO 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Figure 3: Distributions of the transverse momentum of the two hardest jets and angular distributions in the process pp → e + µ + νe νµ + 2 jets at leading and next-to-leading order in perturbative QCD for inclusive two-jet events. The bands show renormalisation and factorisation scale uncertainty, for 50 GeV ≤ µ ≤ 400 GeV. Solid lines show leading and next-to-leading order predictions for µ = 150 GeV. Acknowledgments I wish to thank the organisers of the Moriond QCD session for providing both financial support and a fantastic conference. This write-up is based on work done in collaboratoration with Kirill Melnikov, Raoul Röntsch and Giulia Zanderighi and closely follows Ref. 1 , and the research is supported by the British Science and Technology Facilities Council. References 1. T. Melia, K. Melnikov, R. Rontsch, and G. Zanderighi, JHEP 12, 053 (2010). 2. A. Kulesza and W. J. Stirling, Phys. Lett. B475, 168 (2000); E. Maina, JHEP 0909, 081 (2009); J. R. Gaunt, C. H. Kom, A. Kulesza and W. J. Stirling, hep-ph/1003.3953. 3. H. K. Dreiner, S. Grab, M. Krämer and M. K. Trenkel, Phys. Rev. D75, 035003 (2007). 4. H. Zhang, E. Berger, Q. Cao, C. Chen, and G. Shaughnessy, Phys. Lett. B 696, 68 (2011); T. Han, I. Lewis and T. McElmurry, JHEP 1001, 123 (2010). 5. See e.g. J. Maalampi and N. Romanenko, Phys. Lett. B 532, 202 (2002). 6. T. Melia, K. Melnikov, R. Rontsch, and G. Zanderighi, arxiv:1104.2327. 7. R. K. Ellis, W. T. Giele and Z. Kunszt, JHEP 0803, 003 (2008). 8. W. T. Giele, Z. Kunszt and K. Melnikov, JHEP 0804, 049 (2008). 9. R. K. Ellis, W. T. Giele, Z. Kunszt, K. Melnikov and G. Zanderighi, JHEP 0901, 012 (2009). 10. T. Melia, P. Nason, R. Rontsch, and G. Zanderighi, arxiv:1102.4846. 11. M. Cacciari, G. P. Salam and G. Soyez, JHEP 0804, 063 (2008). 12. A. D. Martin, W. J. Stirling, R. S. Thorne and G. Watt, Eur. Phys. J. C 63, 189 (2009). dΣdΦ e,Μ fb Φe,Μ
W/Z+Jets and W/Z+HF Production at the Tevatron Stefano Camarda Institut de Física d’Altes Energies. Barcelona, 01893-E, Spain On behalf of the CDF and DO Colaborations. The CDF and D0 Collaborations have a comprehensive program of studying the production of vector bosons, W and Z, in association with energetic jets. Understanding the standard model W/Z+jets and W/Z+c, b-jets processes is of paramount importance for the top quark physics, for the Higgs boson and for many new physics searches. In this contribution recent measurements of the associated production of jets and vector bosons in Run II at the Tevatron are presented. The measurements are compared to predictions from various theoretical models. 1 Introduction The study of the production of electroweak bosons in asociation with jets of hadrons constitutes a fundamental item in the high-pT physics program at Tevatron. Vector bosons plus jets final states are a major background to many interesting physics processes like single and pair top quarks production, SM Higgs, and supersymmetry. Precise measurements of W/Z + jets production provide a stringent test of pQCD predictions 1 at high Q 2 , and offer the possibility to validate Monte Carlo simulation tools 2 . The latest vector boson plus jets results at Tevatron are reviewed and discussed. 2 W/Z + Jets measurements The CDF experiment recently measured the Z + jets production cross sections in the Z/γ∗ → µ + µ − decay channel with ∼ 6fb−1 of integrated luminosity 3 . Differential cross sections as a function of p jet T , |y|jet , and jet multiplicity, have been measured. Events are required to have two opposite signed muons with a reconstructed invariant mass in the range 66 MZ 116 GeV/c2 around the Z boson mass. Jets are clustered with the Midpoint algorithm 5 in a cone radius of 0.7, and are required to have pT 30 GeV/c and |y| 2.1. The background estimation is performed both with data-driven and MC techniques, the QCD and W+jet backgrounds are estimated from data using a same charge dimuon sample, other backgrounds contributions like Z+γ, t¯t and diboson are estimated from MC. The cross sections are unfolded back to the particle level accounting for acceptance and smearing effects employing Alpgen + Pythia MC. The data is compared to NLO pQCD predictions obtained with the MCFM program. The theoretical predictions include parton-to-particle correction factors that account for the non-perturbative underlying event and fragmentation effects, estimated with pythia Monte Carlo simulations. Figure 1 (left) shows the measured inclusive differential cross section in Z + 1 jet events. The corrected NLO predictions agree with the data within experimental and systematic uncertainties over the full p jet T range. An update on the Z + jets production cross section in the Z/γ∗ → e + e−
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2011 QCD and High Energy Interactio
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Proceedings of the XLVIth RENCONTRE
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2011 RENCONTRES DE MORIOND The XLVI
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Foreword Contents 1. Higgs Searches
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1. Higgs
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95% CL Limit/SM 10 1 Tevatron Run I
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Events/5 GeV 6 10 5 10 4 10 3 10 2
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Events / 0.5 CDF Run II Preliminary
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For the most sensitive sub-channel
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Table 1: Table listing the various
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various SM Higgs mass hypotheses. T
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constraints on parameters are given
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Figure 2: Invariant mass of the ele
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Figure 4: CDF Exclusion limits for
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Table 1: Main phases of 2010 commis
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Table 4: Parameter list for early (
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luminosity of 1.2×10 33 cm −2 s
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2 QCD Analysis settings HERA PDFs a
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min 2 - 2 20 15 10 5 0 H1 and ZEUS
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SM σ / σ 95% CL Limit on 3 10 2 1
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NNLO σ/ σSM 95% CL Upper Bound on
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the report of this working group. I
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2.3 The impact of different PDF par
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SUSY Searches at the Tevatron Ph. G
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on the quality (loose or tight) and
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SUSY searches at ATLAS N. Barlow, o
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channel. These results are combined
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Figure 2: The top left plot shows t
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2010 data. Analysis techniques for
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as main discriminator between event
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sign leptons is particularly intere
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N of events 5 10 DATA 10 4 3 10 10
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) [pb] ν e → B(W’ × σ 10 1 -
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2 Searches in the dijet final state
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ing that the neutrinos were the onl
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The Quasi-Classical Model in SU(N)
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g (γ µ kµ) γ µ Aa µ g (pk)
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3. Top
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of their vertex with respect to the
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of about 9%. 3.1 Differential Cross
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Figure 5: Summary of most recent CD
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the minimum number of jets identifi
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where f’s are probability functio
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hood technique, with a simultaneous
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momentum direction of the b quark f
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Events 200 150 100 50 -1 DØ L=5.4
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after all corrections in the M t¯t
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for prompt J/ψ under the fully tra
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2 Events / 20 MeV/c 50 40 30 20 10
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ATLAS - consists of four parts (mon
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5 D mesons High cross-sections of D
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μ +X') [nb/GeV] → b+X → (pp T
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GeV) μ |
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HEAVY FLAVOUR IN A NUTSHELL Robert
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Figure 1: Overlapping constraints o
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Figure 3: Constraints on new physic
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RECENT B PHYSICS RESULTS FROM THE T
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(IP) distributions are fitted separ
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decays CDF extracts Using a 5.94 fb
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Search for B 0 s → µ+ µ − and
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Ref. 10,11 . The expected GL distri
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IN PURSUIT OF NEW PHYSICS WITH B DE
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τK + K −/τBs 1.01 1.00 0.99 0.9
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CHARMLESS HADRONIC B-DECAYS AT BABA
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surements (fL ∼ 0.5). Several att
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Estimating the Higher Order Hadroni
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the resulting exponent suggests to
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The counterpart of the ground-state
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(a) Tree level signal decay b ¯Bs
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the B0 d system LHCb profits from i
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This result is based on averaging o
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y non-perturbative effects. Using t
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e M(Dπ) distributions obtained D +
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CHARM PHYSICS RESULTS AND PROSPECTS
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LHCb is working towards its first m
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Two body hadronic D decays Yu Fushe
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where the effective coefficients aA
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6. J. J. Sakurai, Phys. Rev. 156, 1
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states: 6π, 2K4π, 4K2π, KSK3π 1
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Page 174 and 175: conservation. This second principle
Page 176 and 177: many of them come from gluon nonper
Page 179 and 180: Latest Jets Results from the Tevatr
Page 181 and 182: in for the inclusive trijet event s
Page 183 and 184: RECENT RESULTS ON JETS FROM CMS F.
Page 185 and 186: dy (pb/GeV) /dp 2 d 10 10 10 9 10
Page 187 and 188: RECENT RESULTS ON JETS WITH ATLAS G
Page 189 and 190: | y| < 0.3 ATLAS Preliminary 2.1 <
Page 191 and 192: EPOS 2 and LHC Results TanguyPierog
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Page 195 and 196: ABOUT THE HELIX STRUCTURE OF THE LU
Page 197 and 198: Figure 2: Left: Correlations betwee
Page 199 and 200: Improving NLO-parton shower matched
Page 201 and 202: due to the inclusion of higher orde
Page 203 and 204: New Results in Soft Gluon Physics C
Page 205 and 206: Figure 2: Spacetime depiction of Dr
Page 207 and 208: Central Exclusive Meson Pair Produc
Page 209 and 210: in the CEP cross section. However i
Page 211 and 212: AN AVERAGE b-QUARK FRAGMENTATION FU
Page 213 and 214: 1/N dN/dx 3.5 3 2.5 2 1.5 1 0.5 ALE
Page 215 and 216: W + W + jj at NLO in QCD: an exotic
Page 217: Σ fb Σ fb 3.5 3.0 2.5 2.0 0.65 0.
Page 221 and 222: Figure 2: Measured inclusive jet di
Page 223 and 224: W and Z physics with the ATLAS dete
Page 225 and 226: SHERPA 9 MC generators but not by P
Page 227 and 228: W/Z + Jets results from CMS V. CIUL
Page 229 and 230: Events / 0.1 600 500 400 300 200 10
Page 231 and 232: TEVATRON RESULTS ON MULTI-PARTON IN
Page 233 and 234: iterative midpoint cone algorithm w
Page 235 and 236: INVESTIGATIONS OF DOUBLE PARTON SCA
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Page 239 and 240: Figure 4: Two-dimensional distribut
Page 241 and 242: SOFT QCD RESULTS FROM ATLAS AND CMS
Page 243 and 244: as a function of multiplicity for t
Page 245 and 246: Determination of αS using hadronic
Page 247 and 248: α S (m Z 0) 0.15 0.14 0.13 0.12 0.
Page 249 and 250: Reaching beyond NLO in processes wi
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Page 253 and 254: Nonlocal Condensate Model for QCD S
Page 255 and 256: The lower bound for the integration
Page 257 and 258: AN ALTERNATIVE SUBTRACTION SCHEME F
Page 259 and 260: where MBorn,g is the underlying Bor
Page 261 and 262: THE NNPDF2.1 PARTON SET F. CERUTTI
Page 263 and 264: ottom masses mb of 4.25, 4.5, 5.0 a
Page 265 and 266: HOLOGRAPHIC DESCRIPTION OF HADRONS
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Nuclear matter and chiral phase tra
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fact that for Nc ≫ 3 a gas of fre
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Recent Results on Light Hadron Spec
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Figure 3: Mass spectrum fitting wit
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MEASUREMENT OF THE J/ψ INCLUSIVE P
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2 Counts per 40 MeV/c 120 100 80 60
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STUDY OF Ke4 DECAYS IN THE NA48/2 E
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photons were accepted while particl
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6. Structure Functions Diffraction
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2 Hadronic Final States and Diffrac
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3 Summary A brief overview of recen
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Using HERA Data to Determine the In
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k f n 0.4 0.2 0 -0.2 0.4 0.2 0 -0.2
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The singular term, on the other han
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Pomeron Kernel: The leading order B
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DIFFRACTION, SATURATION AND pp CROS
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In Ref. 6 , the saturated Froissart
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Transverse Energy Flow with Forward
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1/N d dE t /dη 0.1 0.09 0.08 0.07
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7. Heavy Ions
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dη)/(0.5〈 N 〉 ) part ch (dN 10
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) 3 (fm long R side R out R 400 350
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correlation density is computed as
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Away-side gaussian width 1.4 1.2 1
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Figure 1: (a) J/ψ rapidity distrib
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lower x, or forward rapidity one ex
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φ ∆ /d assoc dN trig 1/N 0.5 0.4
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AA,Pythia I 2.5 2.0 1.5 1.0 0.5 0.0
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(1/N ) dN/dA evt J φ Δ ) dN/d (1/
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[GeV] Tower ET Σ 50 45 40 35 30 25
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3 Results 3.1 Dijet Properties in p
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(GeV/c) (GeV/c) T T p < 40 20
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wheredσm(N +N → h+X)/dp Tdy isth
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R AA 0.6 0.5 0.4 0.3 0.2 0.1 0 0.5
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Here D is the diffusion coefficient
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The effect of triangular flow in je
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When both trigger and associated pa
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The first Z boson measurement in th
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Figure 1: Dimuon invariant mass spe
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2. V. Kartvelishvili, R. Kvatadze a
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esolution [ µ m] ! r 0 d 300 250 2
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Figure 5: Differential transverse m
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Figure 1: Average nuclear modificat
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Another way of using direct photons
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Pb R g 2 Nuclear Modifications for
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q T 1/R AA 1.6 1.4 1.2 1 0.8 LO Fra
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] 2 > [g/cm max
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Methods (a) and (c) constrain the e
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EXPERIMENTAL SUMMARY: ENTERING THE
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ut also for valence quarks involved
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The sensitivity to Standard Model H
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Figure 10: Top pair mass spectrum m
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Figure 13: Particle densities (left
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4 Low energy precision Spectroscopy
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asymmetries associated to Bd and Bs
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XLVIth Rencontres de Moriond QCD an
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