Author
J. Adam
Bio: J. Adam is an academic researcher from Brookhaven National Laboratory. The author has contributed to research in topics: Meson & Pseudorapidity. The author has an hindex of 8, co-authored 12 publications receiving 173 citations.
Topics: Meson, Pseudorapidity, Charged particle, Antimatter, Jet (fluid)
Papers
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TL;DR: In this paper, the first evidence of a non-monotonic variation in the kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of collision energy was reported.
Abstract: Nonmonotonic variation with collision energy (sqrt[s_{NN}]) of the moments of the net-baryon number distribution in heavy-ion collisions, related to the correlation length and the susceptibilities of the system, is suggested as a signature for the quantum chromodynamics critical point. We report the first evidence of a nonmonotonic variation in the kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of sqrt[s_{NN}] with 3.1 σ significance for head-on (central) gold-on-gold (Au+Au) collisions measured solenoidal tracker at Relativistic Heavy Ion Collider. Data in noncentral Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of sqrt[s_{NN}].
101 citations
TL;DR: In this paper, the authors reported the first measurement of rapidity-odd directed flow (v1) for D^{0} and D^{ 0}[over ¯] mesons at midrapidity (|y| < 0.8) in Au+Au collisions at relativistic heavy ion collisions.
Abstract: We report the first measurement of rapidity-odd directed flow (v_{1}) for D^{0} and D^{0}[over ¯] mesons at midrapidity (|y|<0.8) in Au+Au collisions at sqrt[s_{NN}]=200 GeV using the STAR detector at the Relativistic Heavy Ion Collider. In 10-80% Au+Au collisions, the slope of the v_{1} rapidity dependence (dv_{1}/dy), averaged over D^{0} and D^{0}[over ¯] mesons, is -0.080±0.017(stat)±0.016(syst) for transverse momentum p_{T} above 1.5 GeV/c. The absolute value of D^{0} meson dv_{1}/dy is about 25 times larger than that for charged kaons, with 3.4σ significance. These data give a unique insight into the initial tilt of the produced matter, and offer constraints on the geometric and transport parameters of the hot QCD medium created in relativistic heavy-ion collisions.
59 citations
TL;DR: The first measurement of the charmed baryon production at midrapidity (|y|<1) in Au+Au collisions at the Relativistic Heavy Ion Collider was reported in this paper.
Abstract: We report on the first measurement of the charmed baryon Λ_{c}^{±} production at midrapidity (|y|<1) in Au+Au collisions at sqrt[s_{NN}]=200 GeV collected by the STAR experiment at the Relativistic Heavy Ion Collider. The Λ_{c}/D^{0} [denoting (Λ_{c}^{+}+Λ_{c}^{-})/(D^{0}+D[over ¯]^{0})] yield ratio is measured to be 1.08±0.16 (stat)±0.26 (sys) in the 0%-20% most central Au+Au collisions for the transverse momentum (p_{T}) range 3
48 citations
TL;DR: In this paper, the Breit-wheeler process was investigated through the observation of 6085 exclusive electron-positron pairs in ultra-peripheral Au + Au collisions at 200$ GeV.
Abstract: The Breit-Wheeler process which produces matter and antimatter from photon collisions is experimentally investigated through the observation of 6085 exclusive electron-positron pairs in ultraperipheral
Au + Au collisions at $\sqrt{s_{NN}} = 200$ GeV. The measurements reveal a large fourth-order angular modulation of
cos
4
Δ
ϕ
=
(
16.8
±
2.5
)
%
and smooth invariant mass distribution absent of vector mesons (
ϕ
,
ω
, and
ρ
) at the experimental limit of
≤
0.2
%
of the observed yields. The differential cross section as a function of $e^+e^-$
pair transverse momentum $P_{\perp}$ peaks at low value with $\sqrt{\left \langle P^2_\perp \right \rangle} = 38.1 \pm 0.9$ MeV and displays a significant centrality dependence. These features are consistent with QED calculations for the collision of linearly polarized photons quantized from the extremely strong electromagnetic fields generated by the highly charged Au nuclei at ultrarelativistic speed. The experimental results have implications for vacuum birefringence and for mapping the magnetic field which is important for emergent QCD phenomena.
47 citations
Brookhaven National Laboratory1, AGH University of Science and Technology2, Ohio State University3, University of Kentucky4, Joint Institute for Nuclear Research5, Panjab University, Chandigarh6, Variable Energy Cyclotron Centre7, Kurchatov Institute8, Texas A&M University9, Central China Normal University10, Kent State University11, University of Tarapacá12, University of California, Riverside13, State University of New York System14, University of Houston15, University of Jammu16, Czech Technical University in Prague17, National Research Nuclear University MEPhI18, Rice University19, Yale University20, University of California, Davis21, University of California, Los Angeles22, National Cheng Kung University23, Shandong University24, Fudan University25, University of Science and Technology of China26, Tsinghua University27, Creighton University28, University of California, Berkeley29, Eötvös Loránd University30, Abilene Christian University31, Heidelberg University32, Lawrence Berkeley National Laboratory33, Purdue University34, Wayne State University35, University of Tsukuba36, University of Illinois at Chicago37, Lehigh University38, Southern Connecticut State University39, Technische Universität Darmstadt40, Temple University41, Valparaiso University42, Indian Institute of Science43
TL;DR: In this article, the global polarization of Ξ and Ω hyperons has been measured for the first time in Au+Au collisions at square root n = 200 GeV.
Abstract: Global polarization of Ξ and Ω hyperons has been measured for the first time in Au+Au collisions at sqrt[s_{NN}]=200 GeV. The measurements of the Ξ^{-} and Ξ[over ¯]^{+} hyperon polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay Ξ→Λ+π, as well as by measuring the polarization of the daughter Λ hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over Ξ^{-} and Ξ[over ¯]^{+}, is measured to be ⟨P_{Ξ}⟩=0.47±0.10(stat)±0.23(syst)% for the collision centrality 20%-80%. The ⟨P_{Ξ}⟩ is found to be slightly larger than the inclusive Λ polarization and in reasonable agreement with a multiphase transport model. The ⟨P_{Ξ}⟩ is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. The global polarization of Ω, ⟨P_{Ω}⟩=1.11±0.87(stat)±1.97(syst)% was obtained by measuring the polarization of daughter Λ in the decay Ω→Λ+K, assuming the polarization transfer factor C_{ΩΛ}=1.
37 citations
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TL;DR: The Electron-Ion Collider (EIC) is a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons as discussed by the authors .
113 citations
TL;DR: In this paper , a blind analysis of a large data sample of approximately 3.8 billion isobar collisions of Ru4496+Ru4496 and Zr4096+Zr 4096 at sNN=200 GeV was performed.
Abstract: The chiral magnetic effect (CME) is predicted to occur as a consequence of a local violation of P and CP symmetries of the strong interaction amidst a strong electromagnetic field generated in relativistic heavy-ion collisions. Experimental manifestation of the CME involves a separation of positively and negatively charged hadrons along the direction of the magnetic field. Previous measurements of the CME-sensitive charge-separation observables remain inconclusive because of large background contributions. To better control the influence of signal and backgrounds, the STAR Collaboration performed a blind analysis of a large data sample of approximately 3.8 billion isobar collisions of Ru4496+Ru4496 and Zr4096+Zr4096 at sNN=200 GeV. Prior to the blind analysis, the CME signatures are predefined as a significant excess of the CME-sensitive observables in Ru+Ru collisions over those in Zr+Zr collisions, owing to a larger magnetic field in the former. A precision down to 0.4% is achieved, as anticipated, in the relative magnitudes of the pertinent observables between the two isobar systems. Observed differences in the multiplicity and flow harmonics at the matching centrality indicate that the magnitude of the CME background is different between the two species. No CME signature that satisfies the predefined criteria has been observed in isobar collisions in this blind analysis.20 MoreReceived 31 August 2021Accepted 7 December 2021DOI:https://doi.org/10.1103/PhysRevC.105.014901©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle correlations & fluctuationsQuark-gluon plasmaRelativistic heavy-ion collisionsNuclear Physics
103 citations
TL;DR: In this paper , the authors review the advances made during the last decade, with a focus on theory and phenomenology, to account for non-perturbative physics (e.g. the Schwinger effect), with extreme intensities requiring resummation of the loop expansion.
80 citations
Shreyasi Acharya1, Dagmar Adamová2, Alexander Adler3, Jonatan Adolfsson4 +1019 more•Institutions (109)
TL;DR: These observations challenge some recent theoretical calculations, which predicted a negative and an order of magnitude smaller value of dΔv_{1}/dη for both light flavor and charmed hadrons.
Abstract: The first measurement at the LHC of charge-dependent directed flow (v1) relative to the spectator plane is presented for Pb-Pb collisions at √sNN p = 5.02 TeV. Results are reported for charged hadrons and D0 mesons for the transverse momentum intervals pT > 0.2 GeV=c and 3 < pT < 6 GeV=c in the 5%–40% and 10%–40% centrality classes, respectively. The difference between the positively and negatively charged hadron v1 has a positive slope as a function of pseudorapidity η, dΔv1=dη = [1.68 ± 0.49(stat) x 0.41(syst) × 10^−4. The same measurement for D^0 and D¯ ^0 mesons yields a positive value dΔv1/dη = [4.9 ± 1.7(stat) ± 0.6(syst) × 10^−1, which is about 3 orders of magnitude larger than the one of the charged hadrons. These measurements can provide new insights into the effects of the strong electromagnetic field and the initial tilt of matter created in noncentral heavy ion collisions on th e dynamics of light (u, d, and s) and heavy (c) quarks. The large difference between the observed Δv1 of charged hadrons and D0 mesons may reflect different sensitivity of the charm and light quarks to the early time dynamics of a heavy ion collision. These observations challenge some recent theoretical calculations, which predicted a negative and an order of magnitude smaller value of dΔv1=dη for both light flavor and charmed hadrons.
59 citations
TL;DR: In this paper, the effects of jet-induced medium response on a wide variety of experimental observables and their implications on extracting transport properties of the quark-gluon plasma (QGP) in heavy-ion collisions are reviewed.
Abstract: Jet quenching has been used successfully as a hard probe to study properties of the quark-gluon plasma (QGP) in high-energy heavy-ion collisions at both the relativistic heavy-ion collider and the large hadron collider. We will review recent progresses in theoretical and phenomenological studies of jet quenching with jet transport models. Special emphasis is given to effects of jet-induced medium response on a wide variety of experimental observables and their implications on extracting transport properties of the QGP in heavy-ion collisions.
58 citations