2011 QCD and High Energy Interactions - Rencontres de Moriond ...

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ing that the neutrinos were the only contributors to /E T and by choosing |∆η(ν,l)|, |∆φ(ν,l)| and jet assignments which minimized the difference between the two collinear masses in the event. Together, the scalar sum of the transverse energy in the event and the collinear mass was used as a discriminant to separate new physics from the dominant top quark pair production background. In 37 pb−1 , no evidence for fourth generation quarks was found, and a limit of MQ4 > 270 GeV (95% C.L.) was set using a Feldman-Cousins approach. This was the first dilepton search for an up-type fourth generation quark, as well as the first search for fourth generation quarks performed at the LHC. Searches for leptoquarks were performed using 35 pb−1 of data in both the first (eejj and eνjj) and second (µµjj and µνjj) generation channels. The sum of transverse energy in the event ST ≡ p l1 T +pl2 T +pj1 T +pj2 T was used to look for the presence of a new physics signal in the llqq channel. Here, in order to reject background events arising mainly Z with jets, Mll was found by computing the invariant mass of pairs of leptons. In the llνj channel, however, because the neutrino could not be fully reconstructed, only the transverse mass was used to reject the dominant W plus jets background (defined similarly as for the lepton-neutrino pair in the W ′ search). Choosing lepton-jet and jet-neutrino pairs which minimize the difference between the invariant mass of the lepton-jet MLQ and transverse mass of the jet-neutrino M T LQ , the average ¯ MLQ between them was used as a discriminant in the lνqq channel. The data were found to be consistent with SM expectations, and using a modified frequentist approach, 95% C.L limits on the leptoquark mass were set as a function of the branching fraction β for a single leptoquark to decay to a charged lepton + jet. For first generation leptoquarks, lower limits of M > 376 (319) GeV for β=1.0 (0.5) were found. In the second generation, the lower limits found were M > 422 (362) GeV for β=1.0 (0.5). 5 Summary ATLAS has shown that it is able to push the energy frontier to the TeV scale and search for a variety of BSM signatures in the earliest stages of LHC data, in many cases setting the world’s best limits. The knowledge gained from the first round of analyses presented at Rencontres de Moriond has paved the way for future work, and ATLAS eagerly awaits more data in the hopes of discovering new physics at the LHC. References 1. The ATLAS Collaboration, G. Aad et al., The ATLAS Experiment at the CERN Large Hadron Collider, JINST 3, S08003 (2008) 2. TheATLAS Collaboration, G. Aad et al., Search for New Physics in Dijet Mass and Angular Distributions in pp Collisions at √ s=7 TeV Measured with the ATLAS Detector, New J. Phys. 13, 053044 (2011) 3. U. Baur, I.Hinchliffe, and D. Zeppenfeld, Excited Quark Production at Hadron Colliders, Int. J. Mod. Phys A2, 1285 (1987) U. Baur, M. Spira, and P.M. Zerwas, Excited-quark and -lepton production at hadron colliders, Phys. Rev. D42, 815 (1990) 4. P. Frampton and S. Glashow, Chiral Color: An Alternative to the Standard Model, Phys. Lett. B190, 157 (1987) J. Bagger, C. Schmidt, and S. King, Axigluon Production in Hadronic Collisions, Phys. Rev. D37, 1188 (1988) 5. E. Eichten, I.Hinchliffe, K.D. Lane and C. Quigg Supercollider Physics Rev. Mod. Phys. 56, 579 (1984)
P. Chiappetta and M. Perrottet, Possible bounds on compositeness from inclusive one jet production in large hadron colliders, Phys. Lett. B253, 489 (1991) 6. P. Meade and L. Randall, Black Holes and Quantum Gravity at the LHC, JHEP05 2008, 003 (2008) 7. P. Langacker, The Physics of Heavy Z’ Gauge Bosons, Rev. Mod. Phys. 81, 1199 (2009) 8. D. London and J. L. Rosner, Extra Gauge Bosons in E6, Phys. Rev. D34, 1530 (1986) 9. M. Chizhov, V. Bednyakov, and J. Budagov, Proposal for chiral-boson search at LHC via their unique new signature, Physics of Atomic Nuclei 71, 2096 (2008) 10. The ATLAS Collaboration, Search for high mass dilepton resonances in pp collisions at √ s=7 TeV with the ATLAS experiment, arXiv:1103.6218, accepted by Phys. Lett. B (2011) 11. The ATLAS Collaboration, Search for high-mass states with one lepton plus missing transverse momentum in proton-proton collisions at √ s = 7 TeV with the ATLAS detector, accepted by Phys. Lett. B (2011) 12. The ATLAS Collaboration, A Search for High Mass Diphoton Resonances in the Context of the Randall-Sundrum Model in √ s = 7 TeV pp Collisions, ATLAS-CONF-2011-044 (http://cdsweb.cern.ch/record/1338573) 13. L. Randall and R. Sundrum, Large Mass Hierarchy from a Small Extra Dimension, Phys. Rev. Lett. 83, 3370 (1999) 14. The ATLAS Collaboration, Search for Fourth Generation Quarks Decaying to WqWq → llννqq in pp collisions at √ s=7 TeV with the ATLAS Detector, ATLAS-CONF-2011-022 (http://cdsweb.cern.ch/record/1336751) 15. The ATLAS Collaboration, Search for pair production of first or second generation leptoquarks in pp collisions at √ s=7 TeV using the ATLAS detector at the LHC, arxiv:1104.4481, submitted to Phys Rev D (2011)
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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
Page 22 and 23: various SM Higgs mass hypotheses. T
Page 24 and 25: constraints on parameters are given
Page 26 and 27: Figure 2: Invariant mass of the ele
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Page 30 and 31: Table 1: Main phases of 2010 commis
Page 32 and 33: Table 4: Parameter list for early (
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Page 36 and 37: 2 QCD Analysis settings HERA PDFs a
Page 38 and 39: min 2 - 2 20 15 10 5 0 H1 and ZEUS
Page 40 and 41: SM σ / σ 95% CL Limit on 3 10 2 1
Page 42 and 43: NNLO σ/ σSM 95% CL Upper Bound on
Page 44 and 45: the report of this working group. I
Page 46 and 47: 2.3 The impact of different PDF par
Page 49 and 50: SUSY Searches at the Tevatron Ph. G
Page 51 and 52: on the quality (loose or tight) and
Page 53 and 54: SUSY searches at ATLAS N. Barlow, o
Page 55 and 56: channel. These results are combined
Page 57 and 58: Figure 2: The top left plot shows t
Page 59: 2010 data. Analysis techniques for
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Page 64 and 65: sign leptons is particularly intere
Page 66 and 67: N of events 5 10 DATA 10 4 3 10 10
Page 68 and 69: ) [pb] ν e → B(W’ × σ 10 1 -
Page 70 and 71: 2 Searches in the dijet final state
Page 75 and 76: The Quasi-Classical Model in SU(N)
Page 77 and 78: g (γ µ kµ) γ µ Aa µ g (pk)
Page 79: 3. Top
Page 82 and 83: of their vertex with respect to the
Page 84 and 85: of about 9%. 3.1 Differential Cross
Page 86 and 87: Figure 5: Summary of most recent CD
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Page 90 and 91: where f’s are probability functio
Page 92 and 93: hood technique, with a simultaneous
Page 94 and 95: momentum direction of the b quark f
Page 96 and 97: Events 200 150 100 50 -1 DØ L=5.4
Page 98 and 99: after all corrections in the M t¯t
Page 100 and 101: for prompt J/ψ under the fully tra
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Page 104 and 105: ATLAS - consists of four parts (mon
Page 106 and 107: 5 D mesons High cross-sections of D
Page 108 and 109: μ +X') [nb/GeV] → b+X → (pp T
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Page 113 and 114: HEAVY FLAVOUR IN A NUTSHELL Robert
Page 115 and 116: Figure 1: Overlapping constraints o
Page 117 and 118: Figure 3: Constraints on new physic
Page 119 and 120: RECENT B PHYSICS RESULTS FROM THE T
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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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egion of X(3872), which corresponds
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Figure 1: The π 0 recoil mass spec
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η → π + π − π 0 η ′ →
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conservation. This second principle
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many of them come from gluon nonper
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Latest Jets Results from the Tevatr
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in for the inclusive trijet event s
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RECENT RESULTS ON JETS FROM CMS F.
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dy (pb/GeV) /dp 2 d 10 10 10 9 10
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RECENT RESULTS ON JETS WITH ATLAS G
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| y| < 0.3 ATLAS Preliminary 2.1 <
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EPOS 2 and LHC Results TanguyPierog
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positions are randomly distributed
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ABOUT THE HELIX STRUCTURE OF THE LU
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Figure 2: Left: Correlations betwee
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Improving NLO-parton shower matched
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due to the inclusion of higher orde
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New Results in Soft Gluon Physics C
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Figure 2: Spacetime depiction of Dr
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Central Exclusive Meson Pair Produc
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in the CEP cross section. However i
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AN AVERAGE b-QUARK FRAGMENTATION FU
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1/N dN/dx 3.5 3 2.5 2 1.5 1 0.5 ALE
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W + W + jj at NLO in QCD: an exotic
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Σ fb Σ fb 3.5 3.0 2.5 2.0 0.65 0.
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W/Z+Jets and W/Z+HF Production at t
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Figure 2: Measured inclusive jet di
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W and Z physics with the ATLAS dete
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SHERPA 9 MC generators but not by P
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W/Z + Jets results from CMS V. CIUL
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Events / 0.1 600 500 400 300 200 10
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TEVATRON RESULTS ON MULTI-PARTON IN
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iterative midpoint cone algorithm w
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INVESTIGATIONS OF DOUBLE PARTON SCA
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¦ § ¦ ¨ ¥ ¦ ¨ § ¦ © ¦ §
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Figure 4: Two-dimensional distribut
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SOFT QCD RESULTS FROM ATLAS AND CMS
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as a function of multiplicity for t
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Determination of αS using hadronic
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α S (m Z 0) 0.15 0.14 0.13 0.12 0.
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Reaching beyond NLO in processes wi
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dσ/dp t,max [fb/GeV] 10 5 10 4 10
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Nonlocal Condensate Model for QCD S
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The lower bound for the integration
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AN ALTERNATIVE SUBTRACTION SCHEME F
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where MBorn,g is the underlying Bor
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THE NNPDF2.1 PARTON SET F. CERUTTI
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ottom masses mb of 4.25, 4.5, 5.0 a
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HOLOGRAPHIC DESCRIPTION OF HADRONS
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∫ SYM = κ d 4 ( 1 xdzTr 2 h(z)F
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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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