2,116 research outputs found
Conference Summary of QNP2018
This report is the summary of the Eighth International Conference on Quarks
and Nuclear Physics (QNP2018). Hadron and nuclear physics is the field to
investigate high-density quantum many-body systems bound by strong
interactions. It is intended to clarify matter generation of universe and
properties of quark-hadron many-body systems. The QNP is an international
conference which covers a wide range of hadron and nuclear physics, including
quark and gluon structure of hadrons, hadron spectroscopy, hadron interactions
and nuclear structure, hot and cold dense matter, and experimental facilities.
First, I introduce the current status of the hadron and nuclear physics field
related to this conference. Next, the organization of the conference is
explained, and a brief overview of major recent developments is discussed by
selecting topics from discussions at the plenary sessions. They include
rapidly-developing field of gravitational waves and nuclear physics, hadron
interactions and nuclear structure with strangeness, lattice QCD, hadron
spectroscopy, nucleon structure, heavy-ion physics, hadrons in nuclear medium,
and experimental facilities of EIC, GSI-FAIR, JLab, J-PARC, Super-KEKB, and
others. Nuclear physics is at a fortunate time to push various projects at
these facilities. However, we should note that the projects need to be
developed together with related studies in other fields such as gravitational
physics, astrophysics, condensed-matter physics, particle physics, and
fundamental quantum physics.Comment: 10 pages, LaTeX, 1 style file, 3 figure files, Proceedings of Eighth
International Conference on Quarks and Nuclear Physics (QNP2018), November
13-17, 2018, Tsukuba, Japa
Flow fluctuations and long-range correlations: elliptic flow and beyond
These proceedings consist of a brief overview of the current understanding of
collective behavior in relativistic heavy-ion collisions. In particular, recent
progress in understanding the implications of event-by-event fluctuations have
solved important puzzles in existing data -- the "ridge" and "shoulder"
phenomena of long-range two-particle correlations -- and have created an
exciting opportunity to tightly constrain theoretical models with many new
observables.Comment: 10 pages, 2 figures, Proceedings for the 22nd International
Conference On Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter
2011), Annecy, France, May 23 - 28, 2011; includes Fig. 2 which was omitted
from journal submission for lack of spac
Deuterons and space-momentum correlations in high energy nuclear collisions
Using a microscopic transport model together with a coalescence after-burner, we study the formation of deuterons in Au + Au central collisions at s = 200 AGeV . It is found that the deuteron transverse momentum distributions are strongly a ected by the nucleon space-momentum correlations, at the moment of freeze-out, which are mostly determined by the number of rescatterings. This feature is useful for studying collision dynamics at ultrarelativistic energies
Boundary and expansion effects on two-pion correlation functions in relativistic heavy-ion collisions
We examine the effects that a confining boundary together with hydrodynamical
expansion play on two-pion distributions in relativistic heavy-ion collisions.
We show that the effects arise from the introduction of further correlations
due both to collective motion and the system's finite size. As is well known,
the former leads to a reduction in the apparent source radius with increasing
average pair momentum K. However, for small K, the presence of the boundary
leads to a decrease of the apparent source radius with decreasing K. These two
competing effects produce a maximum for the effective source radius as a
function of K.Comment: 6 pages, 5 Eps figures, uses RevTeX and epsfi
Measurements of e(+)e(-) pairs from open heavy flavor in p plus p and d plus A collisions at root S-NN=200 GeV
We report a measurement of e+e− pairs from semileptonic heavy-flavor decays in p+p collisions at √sNN=200 GeV. The e+e− pair yield from b¯b and c¯c is separated by exploiting a double differential fit done simultaneously in dielectron invariant mass and pT. We used three different event generators, pythia, mc@nlo, and powheg, to simulate the e+e− spectra from c¯c and b¯b production. The data can be well described by all three generators within the detector acceptance. However, when using the generators to extrapolate to 4π, significant differences are observed for the total cross section. These difference are less pronounced for b¯b than for c¯c. The same model dependence was observed in already published d+A data. The p+p data are also directly compared with d+A data in mass and pT, and within the statistical accuracy no nuclear modification is seen
Lévy-stable two-pion Bose-Einstein correlations in √sNN=200 GeV Au+Au collisions
We present a detailed measurement of charged two-pion correlation functions in 0–30% centrality √sNN=200 GeV Au+Au collisions by the PHENIX experiment at the Relativistic Heavy Ion Collider. The data are well described by Bose-Einstein correlation functions stemming from Lévy-stable source distributions. Using a fine transverse momentum binning, we extract the correlation strength parameter λ, the Lévy index of stability α, and the Lévy length scale parameter R as a function of average transverse mass of the pair mT. We find that the positively and the negatively charged pion pairs yield consistent results, and their correlation functions are represented, within uncertainties, by the same Lévy-stable source functions. The λ(mT) measurements indicate a decrease of the strength of the correlations at low mT. The Lévy length scale parameter R(mT) decreases with increasing mT, following a hydrodynamically predicted type of scaling behavior. The values of the Lévy index of stability α are found to be significantly lower than the Gaussian case of α=2, but also significantly larger than the conjectured value that may characterize the critical point of a second-order quark-hadron phase transition
Measurements of double-helicity asymmetries in inclusive J/ψ production in longitudinally polarized p+p collisions at √s=510 GeV
We report the double-helicity asymmetry, AJ/ψLL, in inclusive J/ψ production at forward rapidity as a function of transverse momentum pT and rapidity |y|. The data analyzed were taken during √s=510 GeV longitudinally polarized p+p collisions at the Relativistic Heavy Ion Collider in the 2013 run using the PHENIX detector. At this collision energy, J/ψ particles are predominantly produced through gluon-gluon scatterings, thus AJ/ψLL is sensitive to the gluon polarization inside the proton. We measured AJ/ψLL by detecting the decay daughter muon pairs μ+μ− within the PHENIX muon spectrometers in the rapidity range 1.2<|y|<2.2. In this kinematic range, we measured the AJ/ψLL to be 0.012±0.010 (stat) ±0.003 (syst). The AJ/ψLL can be expressed to be proportional to the product of the gluon polarization distributions at two distinct ranges of Bjorken x: one at moderate range x≈5×10−2 where recent data of jet and π0 double helicity spin asymmetries have shown evidence for significant gluon polarization, and the other one covering the poorly known small-x region x≈2×10−3. Thus our new results could be used to further constrain the gluon polarization for x<5×10−2
Centrality dependence of the pseudorapidity density distribution for charged particles in Pb-Pb collisions at root s(NN)=5.02 TeV
We present the charged-particle pseudorapidity density in Pb–Pb collisions at in centrality classes measured by ALICE. The measurement covers a wide pseudorapidity range from −3.5 to 5, which is sufficient for reliable estimates of the total number of charged particles produced in the collisions. For the most central (0–5%) collisions we find , while for the most peripheral (80–90%) we find . This corresponds to an increase of over the results at previously reported by ALICE. The energy dependence of the total number of charged particles produced in heavy-ion collisions is found to obey a modified power-law like behaviour. The charged-particle pseudorapidity density of the most central collisions is compared to model calculations — none of which fully describes the measured distribution. We also present an estimate of the rapidity density of charged particles. The width of that distribution is found to exhibit a remarkable proportionality to the beam rapidity, independent of the collision energy from the top SPS to LHC energies
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