arXiv subjects

D. McGlinchey

Publications and source records attributed to D. McGlinchey.

6 recordsLinked to original sources

arXiv2017

Are minimal conditions for collectivity met in e+e- collisions?

Signatures of collective behavior have been measured in highly relativistic p+p collisions, as well as in p+A, d+A, and 3He+A collisions. Numerous particle correlation measurements in these systems have been successfully described by calculations based on viscous hydrodynamic and transport models. These observations raise the question of the minimum necessary conditions for a system to exhibit collectivity. Recently, numerous scientists have raised the question of whether the quarks and gluons generated in e+e- collisions may satisfy these minimum conditions. In this paper we explore possible signatures of collectivity, or lack thereof, in e+e- collisions utilizing A Multi-Phase Transport (AMPT) framework which comprises melted color strings, parton scattering, hadronization, and hadron re-scattering.

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arXiv2017

PHENIX Overview

These proceedings present highlighted results from PHENIX shown at the Quark Matter 2017 conference.

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arXiv2016

Consequences of high-$x$ proton size fluctuations in small collision systems at RHIC

Recent measurements of jet production rates at large transverse momentum ($p_T$) in the collisions of small projectiles with large nuclei at RHIC and the LHC indicate that they have an unexpected relationship with estimates of the collision centrality. One compelling interpretation of the data is that it captures an $x_p$-dependent decrease in the average interaction strength of the nucleon in the projectile undergoing a hard scattering. A weakly interacting or "shrinking" nucleon in the projectile strikes fewer nucleons in the nucleus, resulting in a particular pattern of centrality-dependent modifications to high-$p_T$ processes. We describe a simple one-parameter geometric implementation of this picture within a modified Monte Carlo Glauber model tuned to $d$$+$Au jet data, and explore two of its major consequences. First, the model predicts a particular projectile-species dependence to the centrality dependence at high-$x_p$, opposite to that expected from an energy loss effect. Second, we find that some of the large centrality dependence observed for forward di-hadron production in $d$$+$Au collisions at RHIC may arise from the physics of the "shrinking" projectile nucleon, in addition to impact parameter-dependent shadowing or saturation effects at low nuclear-$x$. We conclude that analogous measurements in recently collected $p$$+$Au and $^3$He$+$Au collision data at RHIC can provide a unique test of these predictions.

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arXiv2015

PHENIX Measurements of Single Electrons from Charm and Bottom Decays at Midrapidity in Au+Au Collisions

Heavy quarks are an ideal probe of the quark gluon plasma created in heavy ion collisions. They are produced in the initial hard scattering and therefore experience the full evolution of the medium. PHENIX has previously measured the modification of heavy quark production in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV via electrons from semileptonic decays, which indicated substantial modifications of the parent hadron momentum distribution. The PHENIX barrel silicon vertex detector (VTX), installed in 2011, allows for the separation of electrons from charm and bottom hadron decays through the use of displaced vertex measurements. These proceedings present the results of the completed analysis of the 2011 data set using the VTX.

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arXiv2015

Azimuthal Anisotropy Relative to the Participant Plane from AMPT in Central p+Au, d+Au, and $^{3}$He+Au Collisions at $\sqrt{s_{NN}}=200$ GeV

Recent data from p+p and p+Pb collisions at the Large Hadron Collider (LHC), and d+Au and $^3$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) reveal patterns that---when observed in the collision of heavy nuclei---are commonly interpreted as indicators of a locally equilibrated system in collective motion. The comparison of these data sets, including the forthcoming results from p+Au and p+Al collisions at RHIC, will help to elucidate the geometric dependence of such patterns. It has recently been shown that A-Multi-Phase-Transport-Model (AMPT) can describe some of these features in LHC data with a parton-parton scattering cross section comparable to that required to describe A+A data. In this paper, we extend these studies by incorporating a full wave function description of the $^3$He nucleus to calculate elliptical and triangular anisotropy moments $v_2$ and $v_3$ for p+Au, d+Au and $^3$He+Au collisions at the RHIC top energy of 200 GeV. We find reasonable agreement with the measured $v_2$ in d+Au and $^3$He+Au and $v_3$ in $^3$He+Au for transverse momentum ($p_{T}$) $\lesssim$ 1 GeV/c, but underestimate these measurements for higher values of \pt. We predict a pattern of coefficients ($v_{2}$, $v_{3}$) for \pau, dominated by differences in the number of induced local hot spots (i.e. one, two, or three) arising from intrinsic geometry. Additionally, we examine how this substantial azimuthal anisotropy accrues during each individual evolutionary phase of the collision in the AMPT model. The possibility of a simultaneous description of RHIC- and LHC-energy data, the suite of different geometries, and high multiplicity p+p data is an exciting possibility for understanding the underlying physics in these systems.

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arXiv2014

Exploiting Intrinsic Triangular Geometry in Relativistic He3+Au Collisions to Disentangle Medium Properties

Recent results in d+Au and p+Pb collisions at RHIC and the LHC provide evidence for collective expansion and flow of the created medium. We propose a control set of experiments to directly compare particle emission patterns from p+Au, d+Au, and He3+Au or t+Au collisions at the same sqrt(sNN). Using Monte Carlo Glauber we find that a He3 or triton projectile, with a realistic wavefunction description, induces a significant intrinsic triangular shape to the initial medium and that, even with viscous damping, this survives into a significant third order flow moment v3. By comparing systems with one, two, and three initial hot spots, one can disentangle the effects from the initial spatial distribution of the deposited energy and viscous damping. These are key tools to answering the question of how small a droplet of matter is necessary to form a quark-gluon plasma described by nearly inviscid hydrodynamics.

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