K. N. Barish
A5026024540- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- Nuclear reactor physics and engineering
- Particle Detector Development and Performance
- Pulsars and Gravitational Waves Research
- Nuclear physics research studies
- Stochastic processes and statistical mechanics
- Radiation Detection and Scintillator Technologies
- Particle Accelerators and Free-Electron Lasers
- Theoretical and Computational Physics
- Superconducting Materials and Applications
- Statistical Methods and Bayesian Inference
- Fusion materials and technologies
- Markov Chains and Monte Carlo Methods
- Astrophysics and Cosmic Phenomena
- Particle accelerators and beam dynamics
- Complex Network Analysis Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Earth Systems and Cosmic Evolution
- Opinion Dynamics and Social Influence
- Magnetic confinement fusion research
- Algorithms and Data Compression
University of California System
2025
University of California, Riverside
2015-2024
University of Jammu
2023
AGH University of Krakow
2018-2019
Stony Brook University
2019
Brookhaven National Laboratory
2018
Institute of Particle Physics
2005
PHENIX laboratory
2002
Vanderbilt University
2001
University of California, Los Angeles
1997-1999
Transverse momentum spectra for charged hadrons and neutral pions in the range 1 GeV/c<p(T)<5 GeV/c have been measured by PHENIX experiment at RHIC Au+Au collisions root square[s(NN)] = 130 GeV. At high p(T) from peripheral nuclear are consistent with scaling p+p average number of binary nucleon-nucleon collisions. The central significantly suppressed when compared to binary-scaled expectation, also similarly collisions, indicating a novel nuclear-medium effect energies.
The centrality dependence of transverse momentum distributions and yields for ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}},{K}^{\ifmmode\pm\else\textpm\fi{}},p$, $\overline{p}$ in $\text{Au}+\text{Au}$ collisions at $\sqrt{{s}_{NN}}=200\phantom{\rule{0.3em}{0ex}}\text{GeV}$ midrapidity are measured by the PHENIX experiment Relativistic Heavy Ion Collider. We observe a clear particle mass shapes spectra central below $\ensuremath{\sim}2\phantom{\rule{0.3em}{0ex}}\text{GeV}∕c$ ${p}_{T}$....
The anisotropy parameter (v(2)), the second harmonic of azimuthal particle distribution, has been measured with PHENIX detector in Au+Au collisions at sqrt[s(NN)]=200 GeV for identified and inclusive charged production central rapidities (|eta|<0.35) respect to reaction plane defined high (|eta|=3-4 ). We observe that v(2) mesons falls below (anti)baryons p(T)>2 GeV/c, marked contrast predictions a hydrodynamical model. A quark-coalescence model is also investigated.
Transverse momentum spectra of neutral pions in the range 1<pT<10 GeV/c have been measured at midrapidity by PHENIX experiment BNL RHIC Au+Au collisions sNN=200 GeV. The π0 multiplicity central reactions is significantly below yields same sNN peripheral and p+p scaled number nucleon-nucleon collisions. For most bin, suppression factor ∼2.5 pT=2 increases to ∼4–5 pT≈4 GeV/c. At larger pT, remains constant within errors. deficit already apparent semiperipheral smoothly with centrality.Received...
The PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) has measured electrons with $0.3<{p}_{T}<9\text{ }\text{ }\mathrm{GeV}/c$ midrapidity ($|y|<0.35$) from heavy-flavor (charm and bottom) decays in $\mathrm{Au}+\mathrm{Au}$ collisions $\sqrt{{s}_{\mathrm{NN}}}=200\text{ }\mathrm{GeV}$. nuclear modification factor ${R}_{\mathrm{AA}}$ relative to $p+p$ shows a strong suppression central collisions, indicating substantial energy loss of heavy quarks medium produced RHIC...
Transverse momentum spectra of charged hadrons with p(T)<8 GeV/c and neutral pions p(T)<10 have been measured at midrapidity by the PHENIX experiment BNL RHIC in d+Au collisions sqrt[s(NN)]=200 GeV. The yields are compared to those p+p same sqrt[s(NN)] scaled up number underlying nucleon-nucleon d+Au. yield ratio does not show suppression observed central Au+Au RHIC. Instead, there is a small enhancement high particles.
The production of low mass e+e- pairs for m_{e+e-} < 300 MeV/c^2 and 1 p_T <5 GeV/c is measured in p+p Au+Au collisions at sqrt(s_NN)=200 GeV. Enhanced yield above hadronic sources observed. Treating the excess as internal conversions, invariant direct photons deduced. In central collisions, photon over exponential transverse momentum, with inverse slope T = 221 +/- 19 (stat) (syst) MeV. Hydrodynamical models initial temperatures ranging from 300--600 MeV times ~ 0.6 - 0.15 fm/c after...
Flow coefficients v_n for n = 2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at sqrt(s_NN) 200 GeV, are measured relative to event planes \Psi_n determined large rapidity. We report as a function of transverse momentum and collision centrality, study correlations among different order n. The well described by hydrodynamic models which employ Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on interplay between...
Azimuthal angle ($\ensuremath{\Delta}\ensuremath{\phi}$) correlations are presented for a broad range of transverse momentum ($0.4<{p}_{T}<10$ GeV/$c$) and centrality (0--92%) selections charged hadrons from dijets in Au+Au collisions at $\sqrt{{s}_{\mathit{NN}}}=200$ GeV. With increasing ${p}_{T}$, the away-side $\ensuremath{\Delta}\ensuremath{\phi}$ distribution evolves relatively flat shape to concave shape, then convex shape. Comparisons with $p+p$ data suggest that can be divided into...
The PHENIX collaboration at the Relativistic Heavy Ion Collider (RHIC) reports measurements of azimuthal dihadron correlations near midrapidity in $d$$+$Au collisions $\sqrt{s_{_{NN}}}$=200 GeV. These complement recent analyses by experiments Large Hadron (LHC) involving central $p$$+$Pb $\sqrt{s_{_{NN}}}$=5.02 TeV, which have indicated strong anisotropic long-range angular distributions hadron pairs. origin these anisotropies is currently unknown. Various competing explanations include...
Transverse momentum spectra of electrons (${p}_{T}^{e}$) from semileptonic weak decays heavy-flavor mesons in the range $0.3<{p}_{T}^{e}<9.0$ GeV/$c$ have been measured at midrapidity ($|y|<0.35$) by PHENIX experiment Relativistic Heavy Ion Collider $p+p$ and $\mathrm{Au}+\mathrm{Au}$ collisions $\sqrt{{s}_{\mathrm{NN}}}=200$ GeV. In addition, azimuthal anisotropy parameter ${v}_{2}$ has for $0.3<{p}_{T}^{e}<5.0$ collisions. The substantial modification ${p}_{T}^{e}$ compared with as well...
The Λ (Λ[over ¯]) hyperon polarization along the beam direction has been measured in Au+Au collisions at sqrt[s_{NN}]=200 GeV, for first time heavy-ion collisions. dependence on hyperons' emission angle relative to elliptic flow plane exhibits a second harmonic sine modulation, indicating quadrupole pattern of vorticity component direction, expected due flow. is found increase more peripheral collisions, and shows no strong transverse momentum (p_{T}) p_{T} greater than 1 GeV/c. magnitude...
Non-monotonic variation with collision energy ($\sqrt{s_{\rm NN}}$) of the moments net-baryon number distribution in heavy-ion collisions, related to correlation length and susceptibilities system, is suggested as a signature for Quantum Chromodynamics (QCD) critical point. We report first evidence non-monotonic kurtosis times variance net-proton (proxy number) function \rootsnn 3.1$\sigma$ significance, head-on (central) gold-on-gold (Au+Au) collisions measured using STAR detector at RHIC....
The Breit-Wheeler process which produces matter and anti-matter from photon collisions is investigated experimentally through the observation of 6085 exclusive electron-positron pairs in ultra-peripheral Au+Au at $\sqrt{s_{_{NN}}}=200$ GeV. measurements reveal a large fourth-order angular modulation $\cos{4\Delta\phi}=(16.8\pm2.5)\%$ smooth invariant mass distribution absent vector mesons ($\phi$, $\omega$ $\rho$) experimental limit $\le 0.2\%$ observed yields. differential cross section as...
We report a systematic measurement of cumulants, $C_{n}$, for net-proton, proton and antiproton multiplicity distributions, correlation functions, $\kappa_n$, distributions up to the fourth order in Au+Au collisions at $\sqrt{s_{\mathrm {NN}}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4 200 GeV. The $C_{n}$ $\kappa_n$ are presented as function collision energy, centrality kinematic acceptance rapidity, $y$, transverse momentum, $p_{T}$. data were taken during first phase Beam Energy Scan...
This White Paper presents an overview of the current status and future perspective QCD research, based on community inputs scientific conclusions from 2022 Hot Cold Town Meeting. We present progress made in last decade toward a deep understanding both fundamental structure sub-atomic matter nucleon nucleus cold QCD, hot heavy ion collisions. identify key questions research plausible paths to obtaining answers those near future, hence defining priorities our over coming decades.
In heavy-ion collision experiments, the global collectivity of final-state particles can be quantified by anisotropic flow coefficients (𝑣𝑛). The first-order coefficient, also referred to as directed (𝑣1), describes collective sideward motion produced and nuclear fragments in collisions. It carries information on very early stage collision, especially at large pseudorapidity (𝜂), where it is believed generated during passage time. Directed therefore probes onset bulk dynamics thermalization,...
The PHENIX experiment has measured midrapidity ([FORMULA: SEE TEXT]) transverse momentum spectra of electrons as a function centrality in Au+Au collisions at [FORMULA: TEXT]. Contributions from photon conversions and light hadron decays, mainly Dalitz decays pi0 eta mesons, were removed. resulting nonphotonic electron are primarily due to the semileptonic hadrons carrying heavy quarks. Nuclear modification factors determined by comparison p+p collisions. A significant suppression high pT is...
Azimuthal correlations of jet-induced high-pT charged hadron pairs are studied at midrapidity in Au+Au collisions √sNN=200 GeV. The distribution jet-associated partner hadrons (1.0<pT<2.5 GeV/c) per trigger (2.5<pT<4.0 is found to vary with collision centrality, both shape and yield, indicating a significant effect the nuclear medium on jet fragmentation process.Received 1 July 2005DOI:https://doi.org/10.1103/PhysRevLett.97.052301©2006 American Physical Society
The PHENIX experiment at RHIC has measured charged hadron yields mid-rapidity over a wide range of transverse momentum (0.5 < p_T 10 GeV/c) in Au+Au collisions sqrt(s_NN)=200 GeV. data are compared to pi^zero measurements from the same experiment. For both hadrons and neutral pions, per nucleon-nucleon collision significantly suppressed central peripheral collisions. suppression sets gradually increases with increasing centrality Above 4-5 GeV/c p_T, constant almost identical pi^zeroes is...
The invariant differential cross section for inclusive neutral-pion production in p+p collisions at √s=200 GeV has been measured midrapidity (|η|<0.35) over the range 1<pT≲14 GeV/c by PHENIX experiment Relativistic Heavy Ion Collider. Predictions of next-to-leading order perturbative QCD calculations are consistent with these measurements. precision our result is sufficient to differentiate between prevailing gluon-to-pion fragmentation functions.Received 28 April...
The first measurement of direct photons in Au + collisions at (square root)S(NN) = 200 GeV is presented. photon signal extracted as a function the collision centrality and compared to next-to-leading order perturbative quantum chromodynamics calculations. yield shown scale with number nucleon-nucleon for all centralities.
We present results for the charged-particle multiplicity distribution at midrapidity in Au-Au collisions square root of [s(NN)] = 130 GeV measured with PHENIX detector RHIC. For 5% most central we find dN(ch)/d eta(vertical line eta 0) 622+/-1(stat)+/-41(syst). The results, analyzed as a function centrality, show steady rise particle density per participating nucleon centrality.