arXiv subjects

Terence J. Tarnowsky

Publications and source records attributed to Terence J. Tarnowsky.

7 recordsLinked to original sources

arXiv2013

First Study of the Negative Binomial Distribution Applied to Higher Moments of Net-charge and Net-proton Multiplicity Distributions

A study of the first four moments (mean, variance, skewness, and kurtosis) and their products ($κσ^{2}$ and $Sσ$) of the net-charge and net-proton distributions in Au+Au collisions at $\sqrt{\rm s_{NN}}$ = 7.7-200 GeV from HIJING simulations has been carried out. The skewness and kurtosis and the collision volume independent products $κσ^{2}$ and $Sσ$ have been proposed as sensitive probes for identifying the presence of a QCD critical point. A discrete probability distribution that effectively describes the separate positively and negatively charged particle (or proton and anti-proton) multiplicity distributions is the negative binomial (or binomial) distribution (NBD/BD). The NBD/BD has been used to characterize particle production in high-energy particle and nuclear physics. Their application to the higher moments of the net-charge and net-proton distributions is examined. Differences between $κσ^{2}$ and a statistical Poisson assumption of a factor of four (for net-charge) and 40% (for net-protons) can be accounted for by the NBD/BD. This is the first application of the properties of the NBD/BD to describe the behavior of the higher moments of net-charge and net-proton distributions in nucleus-nucleus collisions.

nucl-ex↗

arXiv2012

Long-Range Multiplicity Correlations in Relativistic Heavy Ion Collisions as a Signal for Dense Partonic Matter

A dense form of matter is formed in relativistic heavy ion collisions. The constituent degrees of freedom in this dense matter are currently unknown. Long-range, forward-backward multiplicity correlations (LRC) are expected to arise due to multiple partonic interactions. Model independent and dependent arguments suggest that such correlations are due to multiple partonic interactions. These correlations are predicted in the context of the Dual Parton Model (DPM). The DPM describes soft partonic processes and hadronization. This model indicates that the underlying mechanism creating these long-range multiplicity correlations in the bulk matter is due to multiple partonic interactions. In this thesis, long-range multiplicity correlations have been studied in heavy ion (Au+Au and Cu+Cu) and hadron-hadron ({\it pp}) collisions. The behavior has been studied as a function of pseudorapidity gap ($Δη$) about $η$ = 0, the centrality, atomic number, and incident energy dependence of the colliding particles. Strong, long-range correlations ($Δη>$ 1.0) as a function of $Δη$ are found for central collisions of %(full overlap) heavy ions at an energy of $\sqrt{s_{NN}}$ = 200 GeV. This indicates substantial amounts of dense partonic matter are formed in central heavy ion collisions at an energy of $\sqrt{s_{NN}}$ = 200 GeV.

nucl-ex↗

arXiv2012

Charge Dependence and Scaling Properties of Dynamical $K/π$, $p/π$, and $K/p$ Fluctuations from the STAR Experiment

Dynamical fluctuations in global conserved quantities such as baryon number, strangeness, or charge may be enhanced near a QCD critical point. Charge dependent results from new measurements of dynamical $K/π$, $p/π$, and $K/p$ ratio fluctuations are presented. The STAR experiment has performed a comprehensive study of the energy dependence of these dynamical fluctuations in Au+Au collisions at the energies $\sqrt{s_{NN}}$ = 7.7-200 GeV using the observable, $ν_{\rm dyn}$. These results are compared to previous measurements and to theoretical predictions. Various proposed scaling scenarios that attempt to remove the intrinsic volume dependence of $ν_{\rm dyn}$ and to simplify comparisons between experimental measurements are also considered. Constructing an intensive quantity allows for a direct connection to thermodynamic predictions.

nucl-ex↗

arXiv2009

Probing the Quark-Gluon Phase Transition with Correlations and Fluctuations in Heavy Ion Collisions from the STAR Experiment

The measurement of particle correlations and fluctuations has been suggested as a method to search for the existence of a phase transition in relativistic heavy ion collisions. If quark-gluon matter is formed in the collision of relativistic heavy ions, measuring these correlations could lead to a determination of the presence of partonic degrees of freedom within the collision. Additionally, non-statistical fluctuations in global quantities such as baryon number, strangeness, or charge may be observed near a QCD critical point. Results for short and long-range multiplicity correlations (forward-backward) are presented for several systems (Au+Au and Cu+Cu) and energies (e.g. $\sqrt{s_{NN}}$ = 200, 62.4, and 22.4 GeV). For the highest energy central A+A collisions, the correlation strength maintains a constant value across the measurement region. In peripheral collisions, at lower energies, and in pp data, the maximum appears at midrapidity. Comparison to models with short-range (HIJING) and both short and long-range interactions (Parton String Model) do not fully reproduce central Au+Au data. Preliminary results for K/$π$ fluctuations are also shown as a function of centrality in Cu+Cu collisions at $\sqrt{s_{NN}}$ = 22.4 GeV.

nucl-ex↗

arXiv2007

Energy and System-Size Dependence of Long-Range Multiplicity Correlations from the STAR Experiment

A discussion of results for short and long-range multiplicity correlations (forward-backward) are presented for several systems (Au+Au, Cu+Cu, and pp) and energies (e.g. $\sqrt{s_{NN}}$ = 200, 62.4, and $\approx$ 20 GeV). These correlations are measured with increasing values of a gap in pseudorapidity, from no gap at midrapidity to a separation of 1.6 units ($|η|$ = 0.8). For the highest energy, central A+A collisions, the forward-backward correlation strength maintains a constant value across the measurement region. In peripheral collisions, at lower energies, and in pp data, the maximum appears at midrapidity. This result may indicate the possible formation of high density matter for central A+A collisions at $\sqrt{s_{NN}}$ = 200 GeV.

nucl-ex↗

arXiv2007

Transverse Momentum Distributions and String Percolation Study in p+p, d+Au and Au+Au at $\sqrt{s_{NN}}$ = 200 GeV

Multiparticle production at high energies is described in terms of color strings stretched between the projectile and target. As string density increases, overlap among the strings leads to cluster formation. At some critical density a macroscopic cluster appears, spanning the entire system. This marks the percolation phase transition. Data from p+p, d+Au and Au+Au collisions at 200 GeV has been analyzed using the STAR detector to obtain the percolation density parameter, $η$. For 200 GeV Au+Au collisions, the value of $η$ is found to lie above the critical percolation threshold, while for 200 GeV d+Au collisions it is below the critical value. This supports the idea of string percolation, which at high enough string density is a possible mechanism to explore the hadronic phase transition to a quark-gluon plasma.

nucl-ex↗

arXiv2006

Long-Range Multiplicity Correlations in Au+Au at $\sqrt{s_{NN}}$ = 200 GeV

We present data on long-range multiplicity correlations in ultra-relativistic heavy ion collisions at the top RHIC energy ($\sqrt{s_{NN}}$ = 200 GeV) from the STAR experiment. The data shows a long-range multiplicity correlation extending across a gap of 1.6 units in pseudorapidity. The data is over predicted by a multiparticle production model with hadronization of independent strings, or fusion of two color strings. This can be interpreted in terms of additional dynamical reduction in the number of particle sources.

nucl-ex↗