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Old Dominion University

Series

Quantum chromodynamics

2014

Discipline

Articles 1 - 2 of 2

Full-Text Articles in Physics

Energy Dependence Of Moments Of Net-Proton Multiplicity Distributions At Rhic, L. Adamczyk, J. K. Adkins, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration Jan 2014

Energy Dependence Of Moments Of Net-Proton Multiplicity Distributions At Rhic, L. Adamczyk, J. K. Adkins, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

We report the beam energy (√ˢᴺᴺ = 7.7-200 GeV) and collision centrality dependence of the mean (M), standard deviation (σ), skewness (S), and kurtosis (κ) of the net-proton multiplicity distributions in Au + Au collisions. The measurements are carried out by the STAR experiment at midrapidity (|y| < 0.5) and within the transverse momentum range 0.4 < pT < 0.8 GeV/c in the first phase of the Beam Energy Scan program at the Relativistic Heavy Ion Collider. These measurements are important for understanding the quantum chromodynamic phase diagram. The products of the moments, Sσ and Kσ2, are sensitive to the correlation length of the hot and dense medium created in the collisions and are related to the ratios of baryon number susceptibilities of corresponding orders. The products of moments are found to have values significantly below the Skellam expectation and close to expectations based on independent …


Virtuality Distributions In Application To Ɣɣ* → Π​0 Transition Form Factor At Handbag Level, Anatoly V. Radyushkin Jan 2014

Virtuality Distributions In Application To Ɣɣ* → Π​0 Transition Form Factor At Handbag Level, Anatoly V. Radyushkin

Physics Faculty Publications

We outline basics of a new approach to transverse momentum dependence in hard processes. As an illustration, we consider hard exclusive transition process ɣ*ɣ -> π0 at the handbag level. Our starting point is coordinate representation for matrix elements of operators (in the simplest case, bilocal O(0, z)) describing a hadron with momentum p. Treated as functions of (pz) and z2, they are parametrized through virtuality distribution amplitudes (VDA) Φ(x, σ), with x being Fourier-conjugate to (pz) and σ Laplace-conjugate to z2. For intervals with z+ = 0, we introduce the transverse momentum distribution …