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Measurements of B→J/ψ at forward rapidity in p+p collisions at s=510 GeV
Aidala, C.,Ajitanand, N. N.,Akiba, Y.,Akimoto, R.,Alexander, J.,Alfred, M.,Aoki, K.,Apadula, N.,Asano, H.,Atomssa, E. T.,Attila, A.,Awes, T. C.,Ayuso, C.,Azmoun, B.,Babintsev, V.,Bai, M.,Bai, X.,Banni American Physical Society 2017 Physical Review D Vol.95 No.9
<P>We report the first measurement of the fraction of J/psi mesons coming from B-meson decay (F (B -> J/psi)) in p + p collisions at root s = 510 GeV. The measurement is performed using the forward silicon vertex detector and central vertex detector at PHENIX, which provide precise tracking and distance-of-closest-approach determinations, enabling the statistical separation of J=. due to B-meson decays from prompt J/psi. The measured value of F (B -> J/psi) is 8.1% +/- 2.3% (stat) +/- 1.9% (syst) for J/psi with transverse momenta 0 < p(T) < 5 GeV/c and rapidity 1.2 < vertical bar y vertical bar < 2.2. The measured fraction F (B -> J/psi) at PHENIX is compared to values measured by other experiments at higher center of mass energies and to fixed-order-next-toleading- logarithm and color-evaporation-model predictions. The b (b) over bar cross section per unit rapidity [d sigma/dy(pp -> b (b) over bar)] extracted from the obtained F (B -> J/psi) and the PHENIX inclusive J/psi cross section measured at 200 GeV scaled with color-evaporation-model calculations, at the mean B hadron rapidity y = +/- 1.7 in 510 GeV p + p collisions, is 3.63(-1.70)(+1.92) mu b. It is consistent with the fixed-order-next-toleading- logarithm calculations.</P>
Aidala, C.,Akiba, Y.,Alfred, M.,Andrieux, V.,Aoki, K.,Apadula, N.,Asano, H.,Ayuso, C.,Azmoun, B.,Babintsev, V.,Bagoly, A.,Bandara, N. S.,Barish, K. N.,Bathe, S.,Bazilevsky, A.,Beaumier, M.,Belmont, R. American Physical Society 2018 Physical review letters Vol.120 No.2
<P>During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p+p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p+p collisions predicts only a moderate atomic-mass-number (A) dependence. In contrast, the asymmetries observed at RHIC in p+A collisions showed a surprisingly strong A dependence in inclusive forward neutron production. The observed asymmetry in p+Al collisions is much smaller, while the asymmetry in p+Au collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed A dependence.</P>
Aidala, C.,Akiba, Y.,Alfred, M.,Andrieux, V.,Aoki, K.,Apadula, N.,Asano, H.,Ayuso, C.,Azmoun, B.,Babintsev, V.,Bandara, N. S.,Barish, K. N.,Bathe, S.,Bazilevsky, A.,Beaumier, M.,Belmont, R.,Berdnikov, American Physical Society 2017 Physical Review C Vol.95 No.3
<P>We present measurements of long-range angular correlations and the transverse momentum dependence of elliptic flow v(2) in high-multiplicity p + Au collisions at root S-NN = 200 GeV. A comparison of these results to previous measurements in high-multiplicity d + Au and He-3+Au collisions demonstrates a relation between v(2) and the initial collision eccentricity epsilon(2), suggesting that the observed momentum-space azimuthal anisotropies in these small systems have a collective origin and reflect the initial geometry. Good agreement is observed between the measured v(2) and hydrodynamic calculations for all systems, and an argument disfavoring theoretical explanations based on initial momentum-space domain correlations is presented. The set of measurements presented here allows us to leverage the distinct intrinsic geometry of each of these systems to distinguish between different theoretical descriptions of the long-range correlations observed in small collision systems.</P>
Aidala, C.,Ajitanand, N. N.,Akiba, Y.,Akimoto, R.,Alexander, J.,Alfred, M.,Aoki, K.,Apadula, N.,Asano, H.,Atomssa, E. T.,Awes, T. C.,Ayuso, C.,Azmoun, B.,Babintsev, V.,Bagoly, A.,Bai, M.,Bai, X.,Banni American Physical Society 2017 Physical Review D Vol.95 No.11
<P>The cross section and transverse single-spin asymmetries of mu(-) and mu(+) from open heavy-flavor decays in polarized p + p collisions at pffisffiffi root s = 200 GeV were measured by the PHENIX experiment during 2012 at the Relativistic Heavy Ion Collider. Because heavy-flavor production is dominated by gluon-gluon interactions at ffiffiffi root s = 200 GeV, these measurements offer a unique opportunity to obtain information on the trigluon correlation functions. The measurements are performed at forward and backward rapidity (1.4 < vertical bar y vertical bar < 2.0) over the transverse momentum range of 1.25 < p(T) < 7 GeV/c for the cross section and 1.25 < p(T) < 5 GeV/c for the asymmetry measurements. The obtained cross section is compared to a fixed-order-plus-next-to-leading-log perturbative-quantum-chromodynamics calculation. The asymmetry results are consistent with zero within uncertainties, and a model calculation based on twist-3 three-gluon correlations agrees with the data.</P>
Dielectron production in Au + Au collisions at<sub>sNN</sub>=200GeV
Adare, A.,Aidala, C.,Ajitanand, N. N.,Akiba, Y.,Akimoto, R.,Alexander, J.,Alfred, M.,Al-Ta'ani, H.,Angerami, A.,Aoki, K.,Apadula, N.,Aramaki, Y.,Asano, H.,Aschenauer, E. C.,Atomssa, E. T.,Averbeck, R. American Physical Society 2016 Physical review. C Vol.93 No.1