Effect Of Event Selection On Jetlike Correlation Measurement In D Au Collisions At Sqrt S Mathrm Nn
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Effect Of Event Selection On Jetlike Correlation Measurement In D Au Collisions At Sqrt S Mathrm Nn
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Author :
language : en
Publisher:
Release Date : 2015
Effect Of Event Selection On Jetlike Correlation Measurement In D Au 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.
In this study, dihadron correlations are analyzed in \(\sqrt{s_{\mathrm{NN}}}=200\) GeV d+Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions.
Effect Of Event Selection On Jetlike Correlation Measurement In Mml
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Author :
language : en
Publisher:
Release Date : 2015
Effect Of Event Selection On Jetlike Correlation Measurement In Mml 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.
Dihadron correlations are analyzed in √sNN = 200 GeV d+Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions.
D0 Meson Elliptic Triangular Flows And Event Shape Engineering Study In Au Au Collisions At Square Root S Subscript Nn
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Author : Yue Liang
language : en
Publisher:
Release Date : 2023
D0 Meson Elliptic Triangular Flows And Event Shape Engineering Study In Au Au Collisions At Square Root S Subscript Nn written by Yue Liang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
Heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) provide a unique environment to probe nuclear matter under extremely high temperature and density conditions. Among the many insights that can be provided are studying the Quark Gluon Plasma (QGP) created in these collisions, the interaction of color-charged probes with the QGP, the mechanism of hadronization as well as the nature of phase transition to the deconfined phase. Production of heavy quarks in high-energy nuclear collisions occurs mainly through initial hard scattering, via gluon fusion and quark anti-quark annihilation, since the thermal production in the hot QCD medium is significantly suppressed due to the heavy quark masses. This makes heavy quarks ideal probes of the QGP as they experience the whole medium evolution. The diffusion of a heavy particle through a heat bath of the hot-QCD medium can be quantified by the spatial diffusion coefficient D[subscript]s, in analogy to the Brownian motion in molecular physics. Early calculations based on perturbative methods for the diffusion coefficient for the charm and bottom quarks in a QGP produced values of D[subscript]s(2[pi]T) ~ 30 ~ O(1/[alpha]2[subscript]s) for a strong coupling constant of [alpha][subscript]s ~ 0.3-0.4 and with a value varying only weakly with temperature. We now know that these values for D[subscript]s are too large to account for the open heavy-flavor (HF) observables, including the elliptic flow (v2) of D0 mesons, in heavy-ion collisions at RHIC and the LHC. New measurements, including of higher order flow, with better precision and studying their dependence on collision geometry and size and shape of the produced medium allow us to better constrain the value of D[subscript]s and the heavy quark interaction with the QGP. The Solenoidal Tracker At RHIC (STAR) experiment is one of the two remaining large detector systems at the RHIC. The Time Projection Chamber (TPC) is the main detector at STAR measuring 4.2 m in length and 4 m in diameter, it provides full azimuthal coverage out to ± 1.0 units of rapidity and particle identification down to transverse momenta of 100 MeV/c. The Heavy Flavor Tracker (HFT) silicon vertex upgrade for the STAR experiment, is utilizing active pixel sensors and silicon strip technology and provides excellent track pointing resolution to allow the reconstruction of heavy flavor hadron decays. My thesis work is utilizing the STAR Heavy Flavor Tracker's combined datasets recorded during RHIC 2014 and 2016 runs to measure with improved precision the D0-meson elliptical (v2) and triangular flow (v3) as a function of event centrality (quantity which describes the overlap region between the two colliding nuclei) and D0 transverse momentum. I also present results obtained with a new method of event-shape-engineering (ESE) to study correlations of D0 v2 with the event geometry. The physics results are compared with model simulations. My results confirm that the D0 v2 follows the same number-of-constituent-quark (NCQ) scaling as light flavor hadrons. Non-zero v3 is observed, and by combining the 2014 and 2016 data, I also observe that the v3 also follows the NCQ scaling as light hadrons. Compared to theoretical model calculations, the observed large v2/v3 results demonstrate that charm quarks gain these strong collectivity through the diffusion in the strongly-coupled QGP medium. From the ESE study, I observe that the event-shape q2 dependence of the measured [pi][superscript]±, K[superscript]± and D0 hadrons follow the similar linear dependence with comparable slope in 10-40% Au+Au collisions. This demonstrated that the heavy flavor hadron v2 is driven by the event geometry. These results allow putting strict constraints on the values of the diffusion coefficient D[subscript]s. STAR's v2 results have been included in recent model analyses and provided a constraint on the 2[pi]TD[subscript]s to be around 2-5 near the T[subscript]c region while the temperature dependence from various models remains largely uncertain. The next phase of heavy flavor programs at RHIC and LHC need to focus on better constraining the temperature/momentum dependence on the heavy quark diffusion coefficient. Furthermore, since the bottom quark mass is much larger than that of charm, theoretically, bottom quark transport in QGP medium can be better described by the Langevin simulation. Testing the universality of heavy quark spatial diffusion coefficient between charm and bottom quarks will be also the next focus in RHIC and LHC HF programs.
Measurement Of Non Flow Correlations And Elliptic Flow Fluctuations In Au Au Collisions At Relativistic Heavy Ion Collider
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Author : Burak Han Alver
language : en
Publisher:
Release Date : 2010
Measurement Of Non Flow Correlations And Elliptic Flow Fluctuations In Au Au Collisions At Relativistic Heavy Ion Collider written by Burak Han Alver and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Measurements of collective flow and two-particle correlations have proven to be effective tools for understanding the properties of the system produced in ultrarelativistic nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC). Accurate modeling of the initial conditions of a heavy ion collision is crucial in the interpretation of these results. The anisotropic shape of the initial geometry of heavy ion collisions with finite impact parameter leads to an anisotropic particle production in the azimuthal direction through collective flow of the produced medium. In "head-on" collisions of Copper nuclei at ultrarelativistic energies, the magnitude of this "elliptic flow" has been observed to be significantly large. This is understood to be due to fluctuations in the initial geometry which leads to a significant anisotropy even for most central Cu+Cu collisions. This thesis presents a phenomenological study of the effect of initial geometry fluctuations on two-particle correlations and an experimental measurement of the magnitude of elliptic flow fluctuations which is predicted to be large if initial geometry fluctuations are present. Two-particle correlation measurements in Au+Au collisions at the top RHIC energies have shown that after correction for contributions from elliptic flow, strong azimuthal correlation signals are present at A0 = 0 and A0 ~ 120. These correlation structures may be understood in terms of event-by-event fluctuations which result in a triangular anisotropy in the initial collision geometry of heavy ion collisions, which in turn leads to a triangular anisotropy in particle production. It is observed that similar correlation structures are observed in A Multi-Phase Transport (AMPT) model and are, indeed, found to be driven by the triangular anisotropy in the initial collision geometry. Therefore "triangular flow" may be the appropriate description of these correlation structures in data. The measurement of elliptic flow fluctuations is complicated by the contributions of statistical fluctuations and other two-particle correlations (non-flow correlations) to the observed fluctuations in azimuthal particle anisotropy. New experimental techniques, which crucially rely on the uniquely large coverage of the PHOBOS detector at RHIC, are developed to quantify and correct for these contributions. Relative elliptic flow fluctuations of approximately 30-40% are observed in 6-45% most central Au+Au collisions at s NN= 200 GeV. These results are consistent with the predicted initial geometry fluctuations.
A Study Of Jets At The Star Experiment At The Relativistic Heavy Ion Collider Via Two Particle Correlations
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Author :
language : en
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A Study Of Jets At The Star Experiment At The Relativistic Heavy Ion Collider Via Two Particle Correlations written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on with categories.
Jets have been studied in high energy heavy ion collisions by measuring the angular correlation between particles at high transverse momentum. Differences in the yield and shape of the angular correlations as a function of system size give information on the medium produced in the collision. Such modifications can be used to infer the presence of a Quark-Gluon Plasma phase, wherein parton degrees of freedom are manifest over nuclear rather than nucleonic scales. In the present work, two-particle correlations were studied in \(d+Au\) and \(Au+Au\) collisions at \(\sqrt{s_{NN}}\) = 200 GeV measured by the STAR experiment at RHIC. The technique was extended to include pseudo-rapidity, permitting jets to be characterised in two-dimensions, and enabling the jet shape to be studied in greater detail. Corrections were developed for the incomplete detector acceptance and finite two-track resolution. Both unidentified and identified particle correlations were studied, using charged tracks and neutral strange particles \(\Lambda, \overline{\Lambda}\), and \(K^0_{Short}\) reconstructed from their characteristic \(V\)0 decay topology. The focus of the analysis was the correlation peak centred at zero azimuthal separation, which is significantly enhanced in central \(Au+Au\) collisions compared to lighter systems. The modified peak was found to comprise a jet-like peak broadened in the pseudo-rapidity direction, sitting atop a long range pseudo-rapidity correlation. The former is suggestive of jet modification by the medium, and the latter may indicate a medium response to jets. Correlations with identified particles indicated the modified same side peak may in part be formed from particles originating from the underlying event.
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.
Growth Of Long Range Forward Backward Multiplicity Correlations With Centrality In Au Au Collisions At Sqrt Snn
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Author :
language : en
Publisher:
Release Date : 2010
Growth Of Long Range Forward Backward Multiplicity Correlations With Centrality In Au Au Collisions At Sqrt Snn written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au+Au and p+p collisions at (square root)s{sub NN} = 200 GeV. Strong short and long range correlations (LRC) are seen in central Au+Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short range correlations are observed in peripheral Au+Au collisions. Both the Dual Parton Model (DPM) and the Color Glass Condensate (CGC) predict the existence of the long range correlations. In the DPM the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC longitudinal color flux tubes generate the LRC. The data is in qualitative agreement with the predictions from the DPM and indicates the presence of multiple parton interactions.
Modification Of Jet Properties In Ultrarelativistic D Au Cu Cu And Au Au Collisions At Superscript Square Root Of S Nn
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Author : Wolf Gerrit Holzmann
language : en
Publisher:
Release Date : 2006
Modification Of Jet Properties In Ultrarelativistic D Au Cu Cu And Au Au Collisions At Superscript Square Root Of S Nn written by Wolf Gerrit Holzmann and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Heavy ion fusion reactions categories.
First Measurement Of Bose Einstein Correlations In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2010
First Measurement Of Bose Einstein Correlations In Proton Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Bose-Einstein correlations have been measured using samples of proton-proton collisions at 0.9 and 2.36 TeV center-of-mass energies, recorded by the CMS experiment at the CERN Large Hadron Collider. The signal is observed in the form of an enhancement of pairs of same-sign charged particles with small relative four-momentum. The size of the correlated particle emission region is seen to increase significantly with the particle multiplicity of the event.
Measurement Of Jet Activity In Top Quark Events Using The E Mu Final State With Two B Tagged Jets In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Measurement Of Jet Activity In Top Quark Events Using The E Mu Final State With Two B Tagged Jets In Pp Collisions At Sqrt S 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.