Measurement of charge multiplicity asymmetry correlations in high-energy nucleus-nucleus collisions at root s=200 GeV.
N/A
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
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Results for “GeV”
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System-size dependence of open-heavy-flavor production in nucleus-nucleus collisions at s NN and #8730; =200 GeV
N/A
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Search for dark photons from neutral meson decays in p+p and d+Au collisions at √s NN = 200 GeV
In this study, the standard model (SM) of particle physics is spectacularly successful, yet the measured value of the muon anomalous magnetic moment (g-2) μ deviates from SM calculations by 3.6σ. Several theoretical models attribute this to the existence of a “dark photon,” an additional U(1) gauge boson, which is weakly coupled to ordinary photons. The PHENIX experiment at the Relativistic Heavy Ion Collider has searched for a dark photon, U, in π⁰, η → γe⁺e⁻ decays and obtained upper limits of O(2×10⁻⁶) on U-γ mixing at 90% CL for the mass range 30 < m U < 90 MeV/c². Combined with other experimental limits, the remaining region in the U-γ mixing parameter space that can explain the (g-2) μ deviation from its SM value is nearly completely excluded at the 90% confidence level, with only a small region of 29 < m U < 32 MeV/c² remaining.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Transverse-rapidity y t dependence of the nonjet azimuth quadrupole from 62- and 200-GeV Au-Au collisions
Not Available
Kettler, David T.↗
Modeling of heavy-flavor pair correlations in Au-Au collisions at 200 A GeV at the BNL Relativistic Heavy Ion Collider
In this paper, we study the nuclear modification of angular and momentum correlations between heavy quark pairs in ultrarelativistic heavy-ion collisions. The evolution of heavy quarks inside the thermalized medium is described via a modified Langevin approach that incorporates both elastic and inelastic interactions with the medium constituents. The spacetime evolution of the fireball is obtained from a (2+1)-dimensional viscous hydrodynamics simulation. The hadronization of heavy quarks is performed by utilizing a hybrid model of fragmentation and coalescence. Our results show that the nuclear modification of the transverse momentum imbalance of D $\overline{D}$ pairs reflects the total energy loss experienced by the heavy quarks and may help us probe specific regions of the medium. The angular correlation of heavy-flavor pairs, especially in the low- to intermediate-transverse-momentum regime, is sensitive to the detailed energy-loss mechanism of heavy quarks inside the quark-gluon plasma.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
E00-110 experiment at Jefferson Lab Hall A: Deeply virtual Compton scattering off the proton at 6 GeV
We present final results on the photon electroproduction ($\vec{e}p\rightarrow ep\gamma$) cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region from Jefferson Lab experiment E00-110. Results from an analysis of a subset of these data were published before, but the analysis has been improved which is described here at length, together with details on the experimental setup. Furthermore, additional data have been analyzed resulting in photon electroproduction cross sections at new kinematic settings, for a total of 588 experimental bins. Results of the $Q^2$- and $x_B$-dependences of both the helicity-dependent and helicity-independent cross sections are discussed. The $Q^2$-dependence illustrates the dominance of the twist-2 handbag amplitude in the kinematics of the experiment, as previously noted. Thanks to the excellent accuracy of this high luminosity experiment, it becomes clear that the unpolarized cross section shows a significant deviation from the Bethe-Heitler process in our kinematics, compatible with a large contribution from the leading twist-2 DVCS$^2$ term to the photon electroproduction cross section. The necessity to include higher-twist corrections in order to fully reproduce the shape of the data is also discussed. The DVCS cross sections in this study represent the final set of experimental results from E00-110, superseding the previous publication.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Measurement of higher cumulants of net-charge multiplicity distributions in Au + Au collisions at s N N = 7.7 – 200 GeV
Our report presents the measurement of cumulants (C n ,n=1,...,4) of the net-charge distributions measured within pseudorapidity (|η|<0.35) in Au+Au collisions at √s NN =7.7–200GeV with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g., C 1 /C 2 , C 3 /C 1 ) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in the ratios of the cumulants as a function of collision energy. These measured values of C 1 /C 2 and C 3 /C 1 can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy. Moreover, the extracted baryon chemical potentials are in excellent agreement with a thermal-statistical analysis model.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
J / ψ production at low transverse momentum in p + p and d + Au collisions at s N N = 200 GeV
In this paper, we report on the measurement of J/ψ production in the dielectron channel at midrapidity (|y| < 1) in p + p and d + Au collisions at s N N = 200 from the STAR experiment at the Relativistic Heavy Ion Collider. The transverse momentum p T spectra in p + p for p T < 4 GeV/c and d + Au collisions for p T < 3 GeV/c are presented. These measurements extend the STAR coverage for J/ψ production in p + p collisions to low p T . The < p$2\atop{T}$ > from the measured J/ψ invariant cross section in p + p and d + Au collisions are evaluated and compared to similar measurements at other collision energies. The nuclear modification factor for J/ψ is extracted as a function of p T and collision centrality in d + Au and compared to model calculations using the modified nuclear parton distribution function and a final-state J/ψ nuclear absorption cross section.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Consequences of high- x proton size fluctuations in small collision systems at s N N = 200 GeV
Not Available
McGlinchey, D.↗
Production of deuterium, tritium, and He 3 in central Pb + Pb collisions at 20 A , 30 A , 40 A , 80 A , and 158 A GeV at the CERN Super Proton Synchrotron
Not Available
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Erratum: Polarization transfer observables in elastic electron-proton scattering at Q 2 =2.5 , 5.2, 6.8, and 8.5GeV 2 [Phys. Rev. C 96 , 055203 (2017)]
Subsequent to the release of our original paper, we discovered in the context of preparing our technical supplement [1] for journal publication that a typographical error had existed in the text file that the analysis program used to construct the beam polarization "database" for both the original analysis, published in Ref. [2], and our final analysis. The electron-beam polarization P e and the analyzing power A y cancel exactly in the ratio R, which is proportional to the ratio P t / P l of the transferred polarization components. On the other hand, the extraction of the relative e dependence of P l / P Born l relies on knowledge of the beam polarization. As such, data taking was interrupted roughly every two days during the GEp - 2γ experiment to perform invasive measurements of the beam polarization using the Hall C Moller polarimeter [3].
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗