Jet Quenching Signatures From Very High Pt Dihadron Correlations In Pb Pb Collisions At Square Root Of S Nn
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Jet Quenching Signatures From Very High Pt Dihadron Correlations In Pb Pb Collisions At Square Root Of S Nn
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Author : Rylan Towne Conway
language : en
Publisher:
Release Date : 2015
Jet Quenching Signatures From Very High Pt Dihadron Correlations In Pb Pb Collisions At Square Root Of S Nn written by Rylan Towne Conway and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Experimental measurements from dihadron correlations triggered with very high-p[subscript]T particles in Pb+Pb collisions at 2.76 TeV are shown. The data set was collected by the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) and corresponds to an integrated luminosity of 150 [mu]b−1. The use of high-p[subscript]T track triggers made it possible to study dihadron correlations up to p[subscript]T ~ 50 GeV/c. The presence of azimuthal anisotropies of final state particles in non-central Pb+Pb collisions gives rise to single-particle correlations that are characterized by the Fourier harmonics, v[subscript]n. To isolate the jet components of the correlations, the v2-v4 components are subtracted from the correlations and the per-trigger-particle associated-yields on the near and away side are studied. The data are compared to correlations from p+p collisions at the same center-of-mass energy over a wide range of trigger and associated-particle p[subscript]T and as a function of Pb+Pb event centrality. On the near-side there is evidence of moderate enhancement at low p[superscript]assc [subscript]T. On the away side there is a significant enhancement at p[superscript]assc [subscript]T ~ 0.5 GeV/c and at higher transverse momentum, p[superscript]assc [subscript]T > 3 GeV/c, there is a suppression of about 50% compared to p+p collisions.
Study Of Jet Quenching With Z Jet Correlations In Pbpb And Pp Collisions At Sqrt S Nn
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Author :
language : en
Publisher:
Release Date : 2017
Study Of Jet Quenching With Z Jet Correlations In Pbpb And Pp Collisions At Sqrt S Nn written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
The production of jets in association with Z bosons, reconstructed via the mu+mu- and e+e- decay channels, is studied in pp and, for the first time, in PbPb collisions. Both data samples were collected by the CMS experiment at the LHC, at a center-of-mass energy of 5.02 TeV. The PbPb collisions were analyzed in the 0-30% centrality range. The back-to-back azimuthal alignment was studied in both pp and PbPb collisions for Z bosons with transverse momentum ptz> 60 GeV/c and a recoiling jet with ptj> 30 GeV/c. The pt imbalance, xjz= ptj/ptz, as well as the average number of jet partners per Z, rjz, were studied in intervals of ptz, in both pp and PbPb collisions. The rjz is found to be smaller in PbPb than in pp collisions, which suggests that in PbPb collisions a larger fraction of partons, associated with the Z bosons, lose energy and fall below the 30 GeV/c ptj threshold.
Correlations Between Jets And Charged Particles In Pbpb And Pp Collisions At Sqrt S Mathrm Nn
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Author :
language : en
Publisher:
Release Date : 2016
Correlations Between Jets And Charged Particles In Pbpb And Pp Collisions At Sqrt S Mathrm Nn written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
In this study, the quark-gluon plasma is studied via medium-induced changes to correlations between jets and charged particles in PbPb collisions compared to pp reference data. This analysis uses data sets from PbPb and pp collisions with integrated luminosities of 166 inverse microbarns and 5.3 inverse picobarns, respectively, collected at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV. The angular distributions of charged particles are studied as a function of relative pseudorapidity ([Delta][eta]) and relative azimuthal angle ([Delta][Phi]) with respect to reconstructed jet directions. Charged particles are correlated with all jets with transverse momentum (pT) above 120 GeV, and with the leading and subleading jets (the highest and second-highest in pT, respectively) in a selection of back-to-back dijet events. Modifications in PbPb data relative to pp reference data are characterized as a function of PbPb collision centrality and charged particle pT. A centrality-dependent excess of low-pT particles is present for all jets studied, and is most pronounced in the most central events. This excess of low-pT particles follows a Gaussian-like distribution around the jet axis, and extends to large relative angles of [Delta][eta] ≈ 1 and [Delta][Phi] ≈ 1.
Measurement Of Jet Quenching With Semi Inclusive Hadron Jet Distributions In Central Pb Pb Collisions At Sqrt S Mathrm Nn
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Author :
language : en
Publisher:
Release Date : 2015
Measurement Of Jet Quenching With Semi Inclusive Hadron Jet Distributions In Central Pb Pb Collisions At Sqrt S Mathrm Nn written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
We report the measurement of a new observable of jet quenching in central Pb-Pb collisions at √sNN = 2.76 TeV, based on the semi-inclusive rate of charged jets recoiling from a high transverse momentum (high-pT) charged hadron trigger. Jets are measured using collinear-safe jet reconstruction with infrared cutoff for jet constituents of 0.15 GeV, for jet resolution parameters R = 0.2, 0.4 and 0.5. Underlying event background is corrected at the event-ensemble level, without imposing bias on the jet population. Recoil jet spectra are reported in the range 20
Studies Of Azimuthal Dihadron Correlations In Ultra Central Pbpb Collisions At Sqrt S Nn
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Author :
language : en
Publisher:
Release Date : 2013
Studies Of Azimuthal Dihadron Correlations In Ultra Central Pbpb Collisions At Sqrt S Nn written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Evidence Of B Jet Quenching In Pbpb Collisions At Sqrt S Nn
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Author :
language : en
Publisher:
Release Date : 2013
Evidence Of B Jet Quenching In Pbpb Collisions At Sqrt S Nn written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Study Of Jet Quenching With Z Jet Correlations In Pbpb And Pp Collisions At Snn
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Author : CMS Collaboration
language : en
Publisher:
Release Date : 2017
Study Of Jet Quenching With Z Jet Correlations In Pbpb And Pp Collisions At Snn written by CMS Collaboration and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Extraction Of Jet Properties From Two Particle Azimuthal Correlations In Pp And Auau Collisions At Square Root Of S Subscript Nn
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Author : Paul Constantin
language : en
Publisher:
Release Date : 2004
Extraction Of Jet Properties From Two Particle Azimuthal Correlations In Pp And Auau Collisions At Square Root Of S Subscript Nn written by Paul Constantin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
Two particle azimuthal correlation functions measured in pp and AuAu collisions at [square root of s subscript NN] = 200 GeV at midrapidity with the central arms of the PHENIX detector are analyzed in order to extract the properties of hadronic jets produced in QCD vacuum and highly excited QCD media, like the jet shape parameters j[Subscript T] and k[Subscript T], the jet conditional yields (number of associated hadrons per high p[Subscript T] trigger hadron), and the jet fragmentation function. The analysis of pp data starts with the measurement of the vacuum fragmentation function from which the p[Subscript T] dependence of the mean fragmentation momentum fraction z is extracted. We obtain a constant value of z = 0.74±0.02 for p[Subscript T] above 3 GeV/c. Soft (non-perturbative) parton fragmentation becomes significant below 3 GeV/c and the slope of the fragmentation function is p[Subscript T] dependent in this region. Gaussian fits to jet induced azimuthal correlations are employed to measure the mean jet fragmentation transverse momentum j[Subscript Ty] = 359 ± 11 (stat) ± 6 (syst) MeV/c and the mean partonic transverse momentum k[Subscript Ty] = 964 ± 49 (stat) ± 16 (syst) MeV/c. The analysis of AuAu data is based on azimuthal correlation functions between charged hadrons in the 1.5-3 GeV/c and 3-5 GeV/c p[Subscript T] regions in five classes of collision centrality. The mean jet fragmentation transverse momentum j[Subscript Ty] is centrality independent and consistent with the value in pp data mentioned above. A strong broadening with the centrality of the extracted mean partonic transverse momentum k[Subscript Ty] (multiplied by z[Subscript trigg]) is observed. This is an important finding because hadronic jet quenching through energy loss is expected to be accompanied by a broadening effect. Another important finding is that the jet conditional yields in both the near (delta phi [Difference] 0) and away (delta phi [Difference] pi) regions exhibit a slightly raising trend with centrality. This was also expected to accompany the jet quenching found at higher p[Subscript T] based on simple energy conservation considerations.
Modification Of Jet Shapes In Pbpb Collisions At Sqrt S Nn
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Author :
language : en
Publisher:
Release Date : 2014
Modification Of Jet Shapes In Pbpb Collisions At Sqrt S Nn written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The first measurement of jet shapes, defined as the fractional transverse momentum radial distribution, for inclusive jets produced in heavy-ion collisions is presented. Data samples of PbPb and pp collisions, corresponding to integrated luminosities of 150 inverse microbarns and 5.3 inverse picobarns respectively, were collected at a nucleon-nucleon centre-of-mass energy of sqrt(s[NN]) = 2.76 TeV with the CMS detector at the LHC. The jets are reconstructed with the anti-kt algorithm with a distance parameter R=0.3, and the jet shapes are measured for charged particles with transverse momentum pt> 1 GeV. The jet shapes measured in PbPb collisions in different collision centralities are compared to reference distributions based on the pp data. A centrality-dependent modification of the jet shapes is observed in the more central PbPb collisions, indicating a redistribution of the energy inside the jet cone. This measurement provides information about the parton shower mechanism in the hot and dense medium produced in heavy-ion collisions.
Properties Of Dijets In Pp Ppb And Pbpb Collisions
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Author : Doga Can Gulhan
language : en
Publisher:
Release Date : 2016
Properties Of Dijets In Pp Ppb And Pbpb Collisions written by Doga Can Gulhan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Two dijet measurements, one using 35 pb-1 pPb data at [square root]sNN- 5.02 TeV, and another with 166 [mu]b-1 PbPb and 5.3 pb-1 pp data at [square root]sNN = 2.76 TeV collected with CMS detector at the LHC, are presented. In pPb collisions, the dijet PT ratios, azimuthal angle differences and pseudorapidity distributions are measured and compared to PYTHIA and PYTHIA+HIJING simulations as well as NLO QCD predictions for the latter observable. No significant signs of final state interactions, such as a decrease in the mean dijet PT ratios or a broadening in the correlation of the dijets in azimuthal angle, with increasing forward activity, are observed. The dijet pseudorapidity distributions are also measured, and are sensitive to nuclear PDFs for x values of 0.001 - 0.5. Selections on event activity are found to yield unexpected centrality biases on dijet pseudorapidity distributions, which aided the interpretation of similar biases seen in inclusive jet measurements by ATLAS. In PbPb collisions, a detailed scan of charged particle distributions in correlation with the dijet system is carried out. The PT projection of charged particles on the dijet axis is measured at different distances of [delta] = [mathematical formula ...] 2 with respect to the leading and subleading jet axes. In this way, the spectra and angular distribution of the additional particles, which recover the overall event balance in dijet events with enhanced PT asymmetry in PbPb compared to pp collisions, are obtained up to [delta] = 1.8 in steps of 0.2. A significant excess of low PT particles associated with a subleading jet at large [delta] values is observed, and this excess is shown to get larger for dijet events with PT asymmetry. The scan is carried out for variety of anti-kT R parameters, which provides a way of varying jet width and fragmentation. Medium response to jet quenching at wide angles for jets with different fragmentation is studied. Only an insignificant increase of the magnitude of low PT particle excess at large angles, but a significant increase in the modification of the balance distribution close to the jet axes is observed by increasing R.