Mon·Aug 18, 2014Monday·August 18, 2014

1. 01*

   Method for High Accuracy Multiplicity Correlation Measurements

   K. Gulbrandsen🇩🇰 · C. Soegaard🇸🇪

   Multiplicity correlation measurements provide insight into the dynamics of high energy collisions. Models describing these collisions need these correlation measurements to tune the strengths of the underlying QCD processes which influence all observables. Detectors, however, often possess limited coverage or reduced efficiency that influence correlation measurements in obscure ways. In this paper, the effects of non-uniform detection acceptance and efficiency on the measurement of multiplicity correlations between two distinct detector regions (termed forward-backward correlations) are derived. An analysis method with such effects built-in is developed and subsequently verified using different event generators. The resulting method accounts for acceptance and efficiency in a model independent manner with high accuracy thereby shedding light on the relative contributions of the underlying processes to particle production.

   nucl-exhep-exPRC(2016)·1 citation
2. 02*

   An Overview of STAR Experimental Results

   N. Xu🇺🇸

   With large acceptance and excellent particle identification, STAR is one of the best mid-rapidity collider experiments for studying high-energy nuclear collisions. The STAR experiment provides full information on initial conditions, properties of the hot and dense medium as well as the properties at freeze-out. In Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV, STAR's focus is on the nature of the sQGP produced at RHIC. In order to explore the properties of the QCD phase diagram, since 2010, the experiment has collected sizable data sets of Au+Au collisions at the lower collision energy region where the net-baryon density is large. At the 2014 Quark Matter Conference, the STAR experiment made 16 presentations that cover physics topics including {\it collective dynamics}, {\it electromagnetic probes}, {\it heavy flavor}, {\it initial state physics}, {\it jets}, {\it QCD phase diagram}, {\it thermodynamics and hadron chemistry}, and {\it future experimental facilities, upgrades, and instrumentation} [1-16]. In this overview we will highlight a few results from the STAR experiment, especially those from the recent measurements of the RHIC beam energy scan program. At the end, instead of a summary, we will discuss STAR's near future physics programs at RHIC.

   nucl-exNPA(2014)·70 citations
3. 03*

   Mass depletion: a new parameter for quantitative jet modification

   A. Majumder🇺🇸 · J. Putschke🇺🇸

   We propose an extension to classify jet modification in heavy-ion collisions by including the jet mass along with its energy. The mass of a jet, as measured by jet reconstruction algorithms, is constrained by the jet's virtuality, which in turn has a considerable effect on such observables as the fragmentation function and jet shape observables. The leading parton, propagating through a dense medium, experiences substantial virtuality (or mass) depletion along with energy loss. Meaningful comparisons between surviving jets and jets produced in $p$-$p$ collisions require mass depletion to be taken into account. Using a vacuum event generator, we show the close relationship between the actual jet mass and that after applying a jet reconstruction algorithm. Using an in-medium event generator, we demonstrate the clear difference between the mass of a surviving parton exiting a dense medium and a parton with a similar energy formed in a hard scattering event. Effects of this difference on jet observables are discussed.

   ↳ nucl-thhep-phnucl-exPRC(2016)·47 citations
4. 04*

   Future Upgrade and Physics Perspectives of the ALICE TPC

   Taku Gunji (for the ALICE Collaboration)🇯🇵

   The ALICE experiment at the Large Hadron Collider (LHC) proposes major detector upgrades to fully exploit the increase of the luminosity of the LHC in RUN~3 and to extend the physics reach for rare probes at low transverse momentum. The Time Projection Chamber (TPC) is one of the main tracking and PID devices in the central barrel of ALICE. The maximum trigger rate of the TPC is currently limited to about 3.5 kHz by the operation of a gating grid system. In order to make full use of the luminosity in RUN 3, the TPC is foreseen to be operated in an ungated mode with continuous readout. The existing MWPC readout will be replaced by a Micro-Pattern Gaseous Detector (MPGD) based readout, which provides intrinsic ion capture capability without gating. Extensive detector R\&D employing Gas Electron Multiplier (GEM) and Micro-Mesh Gaseous detector (Micromegas) technologies, and simulation studies to advance the techniques for the corrections of space-charge distortions have been performed since 2012. In this paper, the expected detector performance and the status of the R\&D program to achieve this ambitious goal are described.

   ↳ physics.ins-dethep-exnucl-exNPA(2014)·5 citations
5. 05*

   Quantitative extraction of the jet transport parameter from combined data at RHIC and LHC

   Xin-Nian Wang (for the JET Collaboration)🇨🇳

   Using theoretical tools developed by the JET Collaboration in which one employes 2+1D or 3+1D hydrodynamic models for the bulk medium evolution and jet quenching models, the combined data on suppression of single inclusive hadron spectra at both RHIC and LHC are systematically analyzed with five different approaches to the parton energy loss. The jet transport parameter is extracted from the best fits to the data with values of $\hat{q}\approx 1.2\pm 0.3$ and $1.9\pm 0.7$ GeV${}^2$/fm in the center of the most central Au+Au collisions at $\sqrt{s}=200$ GeV and Pb+Pb collisions at $\sqrt{s}=2.67$ TeV, respectively at an initial time ${\tau }_0=0.6$ fm/$c$ for a quark jet with an initial energy of 10 GeV/$c$.

   ↳ nucl-thhep-phnucl-exNPA(2014)·3 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.