Publications

2014

1. Nuclear matter effects on J/ψ production in asymmetric Cu+Au collisions at sNN =200 GeV

   Adare A., Aidala C., Ajitanand N. N., Akiba Y., Akimoto R., Alexander J., Alfred M., Aoki K., Apadula N., Aramaki Y., Asano H., Atomssa E. T., Awes T. C., Azmoun B., Babintsev V., Bai M., Bai X., Bandara N. S., Bannier B., Barish K. N., Bathe S., Baublis V., Baumann C., Baumgart S., Bazilevsky A., Beaumier M., Beckman S., Belmont R., Berdnikov A., Berdnikov Y., Bing X., Black D., Blau D. S., Bok J. S., Boyle K., Brooks M. L., Bryslawskyj J., Buesching H., Bumazhnov V., Butsyk S., Campbell S., Chen C. -., Chi C. Y., Chiu M., Choi I. J., Choi J. B., Choi S., Christiansen P., Chujo T., Cianciolo V., Citron Z. H., Cole B. A., Cronin N., Crossette N., Csanad M., Csoergo T., Datta A., Daugherity M. S., David G., DeBlasio K., Dehmelt K., Denisov A., Deshpande A., Desmond E. J., Ding L., Dion A., Do J. H., Drapier O., Drees A., Drees K. A., Durham J. M., Durum A., D'Orazio L., Engelmore T., Enokizono A., En'yo H., Esumi S., Eyser K. O., Fadem B., Feege N., Fields D. E., Finger M., Finger M. J., Fleuret F., Fokin S. L., Frantz J. E., Franz A., Frawley A. D., Fukao Y., Gainey K., Gal C., Gallus P., Garg P., Garishvili A., Garishvili I., Ge H., Giordano F., Glenn A., Gong X., Gonin M., Goto Y., de Cassagnac C. R. G., Grau N., Greene S. V., Perdekamp M. G., Gu Y., Gunji T., Guragain H., Hachiya T., Haggerty J. S., Hahn K. I., Hamagaki H., Han S. Y., Hanks J., Hasegawa S., Hashimoto K., Hayano R., He X., Hemmick T. K., Hester T., Hill J. C., Hollis R. S., Homma K., Hong B., Hoshino T., Huang J., Huang S. -. J., Ichihara T., Ikeda Y., Imai K., Imazu Y., Inaba M., Iordanova A., Isenhower D., Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical Review C. 90, 6, 064908.  Abstract

   We report on J/ψ production from asymmetric Cu+Au heavy-ion collisions at sNN=200 GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/ψ yields in Cu+Au collisions in the Au-going direction is found to be comparable to that in Au+Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J/ψ production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-x gluon suppression in the larger Au nucleus.

   [All authors]
2. PHENIX Collaboration

   Adare A., Afanasiev S., Aidala C., Ajitanand N. N., Akiba Y., Akimoto R., Al-Bataineh H., Al-Ta'ani H., Alexander J., Alfred M., Andrews K. R., Angerami A., Aoki K., Apadula N., Aphecetche L., Appelt E., Aramaki Y., Milov A., Ravinovich I., Tserruya I. et al. (2014) Nuclear Physics A. 932, p. 627-633  Abstract

   [All authors]
3. A centrality detector concept

   Tarafdar S., Citron Z. & Milov A. (2014) Nuclear Instruments & Methods In Physics Research Section A-Accelerators Spectrometers Detectors And Associated Equipment. 768, p. 170-178  Abstract

   The nucleus-nucleus impact parameter and collision geometry of a heavy ion collision are typically characterized by assigning a collision "centrality". In all present heavy ion experiments centrality is measured indirectly, by detecting the number of particles or the energy of the particles produced in the interactions, typically at high rapidity. Centrality parameters are associated to the measured detector response using the Glauber model. This approach suffers from systematic uncertainties related to the assumptions about the particle production mechanism and limitations of the Glauber model. In the collider based experiments there is a unique possibility to measure centrality parameters by registering spectator fragments remaining from the collision. This approach does not require model assumptions and relies on the fact that spectators and participants are related via the total number of nucleons in the colliding species. This paper describes the concept of a centrality detector for heavy ion experiment, which measures the total mass number of all fragments by measuring their deflection in the magnetic field of the collider elements.

4. Particle production and long-range correlations in p+Pb collisions with the ATLAS detector

   Milov A. (2014) Nuclear Physics A. 932, p. 357-364  Abstract

   The ATLAS experiment at the LHC has measured the centrality dependence of charged-particle pseudorapidity distribution, charged-particle spectra, and two-particle correlations in p+Pb collisions at a nucleon-nucleon centre-of-mass energy of sNN=5.02 TeV. Charged particles were measured over |η|

5. Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at √s = 7 TeV with the ATLAS detector

   Aad G., Alon R., Barak L., Bressler S., Citron Z. H., Duchovni E., Gabizon O., Gross E., Groth-Jensen J., Lellouch D., Levinson L. J., Mikenberg G., Milov A., Milstein D., Roth I., Schaarschmidt J., Silbert O., Smakhtin V., Vitells O. et al. (2014) New Journal of Physics. 16, 113013.  Abstract

   This paper presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy of and correspond to an integrated luminosity of . The measurement is performed by reconstructing the boosted W or Z bosons in single jets. The reconstructed jet mass is used to identify the W and Z bosons, and a jet substructure method based on energy cluster information in the jet centre-of-mass frame is used to suppress the large multi-jet background. The cross-section for events with a hadronically decaying W or Z boson, with transverse momentum and pseudorapidity , is measured to be pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques.

   [All authors]
6. Search for the direct production of charginos, neutralinos and staus in final states with at least two hadronically decaying taus and missing transverse momentum in pp collisions at √s = 8 TeV with the ATLAS detector

   Bressler S., Citron Z. H., Duchovni E., Gabizon O., Gross E., Groth-Jensen J., Lellouch D., Levinson L. J., Mikenberg G., Milov A., Milstein D., Pitt M., Roth I. et al. (2014) Journal of High Energy Physics. 2014, 10, 96.  Abstract

   Results of a search for the electroweak associated production of charginos and next-to-lightest neutralinos, pairs of charginos or pairs of tau sleptons are presented. These processes are characterised by final states with at least two hadronically decaying tau leptons, missing transverse momentum and low jet activity. The analysis is based on an integrated luminosity of 20.3 fb^-1 of proton-proton collisions at√s = 8 TeV recorded with the ATLAS experiment at the Large Hadron Collider. No significant excess is observed with respect to the predictions from Standard Model processes. Limits are set at 95% confidence level on the masses of the lighter chargino and next-to-lightest neutralino for various hypotheses for the lightest neutralino mass in simplified models. In the scenario of direct production of chargino pairs, with each chargino decaying into the lightest neutralino via an intermediate tau slepton, chargino masses up to 345 GeV are excluded for a massless lightest neutralino. For associated production of mass-degenerate charginos and next-to-lightest neutralinos, both decaying into the lightest neutralino via an intermediate tau slepton, masses up to 410 GeV are excluded for a massless lightest neutralino.

   [All authors]
7. System-size dependence of open-heavy-flavor production in nucleus-nucleus collisions at sNN =200 GeV

   Adare A., Afanasiev S., Aidala C., Ajitanand N. N., Akiba Y., Al-Bataineh H., Alexander J., Aoki K., Apadula N., Aphecetche L., Armendariz R., Aronson S. H., Asai J., Atomssa E. T., Averbeck R., Awes T. C., Azmoun B., Babintsev V., Baksay G., Baksay L., Baldisseri A., Barish K. N., Barnes P. D., Bassalleck B., Bathe S., Batsouli S., Baublis V., Baumgart S., Bazilevsky A., Belikov S., Bennett R., Berdnikov Y., Bickley A. A., Boissevain J. G., Borel H., Boyle K., Brooks M. L., Buesching H., Bumazhnov V., Bunce G., Butsyk S., Campbell S., Chang B. S., Charvet J. -., Chernichenko S., Chi C. Y., Chiba J., Chiu M., Choi I. J., Chujo T., Chung P., Churyn A., Cianciolo V., Cleven C. R., Cole B. A., Comets M. P., Constantin P., Csanad M., Csoergo T., Dahms T., Das K., David G., Deaton M. B., Dehmelt K., Delagrange H., Denisov A., d'Enterria D., Deshpande A., Desmond E. J., Dietzsch O., Dion A., Donadelli M., Drapier O., Drees A., Durham J. M., Durum A., Dzhordzhadze V., Efremenko Y. V., Egdemir J., Ellinghaus F., Emam W. S., Enokizono A., En'yo H., Esumi S., Eyser K. O., Fields D. E., Finger M., Finger M. J., Fleuret F., Fokin S. L., Fraenkel Z., Frantz J. E., Franz A., Frawley A. D., Fujiwara K., Fukao Y., Fusayasu T., Gadrat S., Garishvili I., Glenn A., Gong H., Gonin M., Gosset J., Goto Y., de Cassagnac C. R. G., Grau N., Greene S. V., Perdekamp M. G., Gunji T., Gustafsson H. -., Hachiya T., Henni A. H., Haegemann C., Haggerty J. S., Hamagaki H., Han R., Harada H., Hartouni E. P., Haruna K., Haslum E., Hayano R., He X., Heffner M., Hemmick T. K., Hester T., Hiejima H., Hill J. C., Hobbs R., Hohlmann M., Holzmann, Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical Review C. 90, 3, 034903.  Abstract

   The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open-heavy-flavor production in Cu+Cu collisions at sNN=200 GeV through the measurement of electrons at midrapidity that originate from semileptonic decays of charm and bottom hadrons. In peripheral Cu+Cu collisions an enhanced production of electrons is observed relative to p+p collisions scaled by the number of binary collisions. In the transverse momentum range from 1 to 5 GeV/c the nuclear modification factor is RAA∼1.4. As the system size increases to more central Cu+Cu collisions, the enhancement gradually disappears and turns into a suppression. For pT>3 GeV/c, the suppression reaches RAA∼0.8 in the most central collisions. The pT and centrality dependence of RAA in Cu+Cu collisions agree quantitatively with RAA in d+Au and Au+Au collisions, if compared at a similar number of participating nucleons.

   [All authors]
8. Centrality categorization for Rp(d)+A in high-energy collisions

   Adare A., Aidala C., Ajitanand N. N., Akiba Y., Al-Bataineh H., Alexander J., Angerami A., Aoki K., Apadula N., Aramaki Y., Atomssa E. T., Averbeck R., Awes T. C., Azmoun B., Babintsev V., Bai M., Baksay G., Baksay L., Barish K. N., Bassalleck B., Basye A. T., Bathe S., Baublis V., Baumann C., Bazilevsky A., Belikov S., Belmont R., Bennett R., Bhom J. H., Blau D. S., Bok J. S., Boyle K., Brooks M. L., Buesching H., Bumazhnov V., Bunce G., Butsyk S., Campbell S., Caringi A., Chen C. -., Chi C. Y., Chiu M., Choi I. J., Choi J. B., Choudhury R. K., Christiansen P., Chujo T., Chung P., Chvala O., Cianciolo V., Citron Z. H., Cole B. A., del Valle V. Z. C., Connors M., Csanad M., Csoergo T., Dahms T., Dairaku S., Danchev I., Das K., Datta A., David G., Dayananda M. K., Denisov A., Deshpande A., Desmond E. J., Dharmawardane K. V., Dietzsch O., Dion A., Donadelli M., Drapier O., Drees A., Drees K. A., Durham J. M., Durum A., Dutta D., D'Orazio L., Edwards S., Efremenko Y. V., Ellinghaus F., Engelmore T., Enokizono A., En'yo H., Esumi S., Fadem B., Fields D. E., Finger M., Finger M. J., Fleuret F., Fokin S. L., Fraenkel Z., Frantz J. E., Franz A., Frawley A. D., Fujiwara K., Fukao Y., Fusayasu T., Garishvili I., Glenn A., Gong H., Gonin M., Goto Y., de Cassagnac C. R. G., Grau N., Greene S. V., Grim G., Perdekamp M. G., Gunji T., Gustafsson H. -. .., Haggerty J. S., Hahn K. I., Hamagaki H., Hamblen J., Han R., Hanks J., Haslum E., Hayano R., He X., Heffner M., Hemmick T. K., Hester T., Hill J. C., Hohlmann M., Holzmann W., Homma K., Hong B., Horaguchi T., Hornback D., Huang S. -. J., Ichihara T., Ichimiya R., Ikeda Y., Imai K., Inaba M., Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical Review C. 90, 3, 034902.  Abstract

   High-energy proton- and deuteron-nucleus collisions provide an excellent tool for studying a wide array of physics effects, including modifications of parton distribution functions in nuclei, gluon saturation, and color neutralization and hadronization in a nuclear environment, among others. All of these effects are expected to have a significant dependence on the size of the nuclear target and the impact parameter of the collision, also known as the collision centrality. In this article, we detail a method for determining centrality classes in p(d)+A collisions via cuts on the multiplicity at backward rapidity (i.e., the nucleus-going direction) and for determining systematic uncertainties in this procedure. For d+Au collisions at sNN=200 GeV we find that the connection to geometry is confirmed by measuring the fraction of events in which a neutron from the deuteron does not interact with the nucleus. As an application, we consider the nuclear modification factors Rp(d)+A, for which there is a bias in the measured centrality-dependent yields owing to auto correlations between the process of interest and the backward-rapidity multiplicity. We determine the bias-correction factors within this framework. This method is further tested using the hijing Monte Carlo generator. We find that for d+Au collisions at sNN=200 GeV, these bias corrections are small and vary by less than 5% (10%) up to pT=10 (20) GeV/c. In contrast, for p+Pb collisions at sNN=5.02 TeV we find that these bias factors are an order of magnitude larger and strongly pT dependent, likely attributable to the larger effect of multiparton interactions.

   [All authors]
9. Low-mass vector-meson production at forward rapidity in p+p collisions at s =200GeV

   Adare A., Aidala C., Ajitanand N. N., Akiba Y., Akimoto R., Al-Ta'ani H., Alexander J., Alfred M., Andrews K. R., Angerami A., Aoki K., Apadula N., Appelt E., Aramaki Y., Armendariz R., Asano H., Aschenauer E. C., Atomssa E. T., Awes T. C., Azmoun B., Babintsev V., Bai M., Bandara N. S., Bannier B., Barish K. N., Bassalleck B., Basye A. T., Bathe S., Baublis V., Baumann C., Bazilevsky A., Beaumier M., Beckman S., Belmont R., Ben-Benjamin J., Bennett R., Berdnikov A., Berdnikov Y., Black D., Blau D. S., Bok J., Bok J. S., Boyle K., Brooks M. L., Broxmeyer D., Bryslawskyj J., Buesching H., Bumazhnov V., Bunce G., Butsyk S., Campbell S., Castera P., Chen C. -., Chi C. Y., Chiu M., Choi I. J., Choi J. B., Choudhury R. K., Christiansen P., Chujo T., Chvala O., Cianciolo V., Citron Z. H., Cole B. A., del Valle V. Z. C., Connors M., Csanad M., Csoergo T., Dairaku S., Datta A., Daugherity M. S., David G., Dayananda M. K., DeBlasio K., Dehmelt K., Denisov A., Deshpande A., Desmond E. J., Dharmawardane K. V., Dietzsch O., Ding L., Dion A., Do J. H., Donadelli M., Drapier O., Drees A., Drees K. A., Durham J. M., Durum A., D'Orazio L., Efremenko Y. V., Engelmore T., Enokizono A., En'yo H., Esumi S., Fadem B., Feege N., Fields D. E., Finger M., Finger M. J., Fleuret F., Fokin S. L., Frantz J. E., Franz A., Frawley A. D., Fukao Y., Fusayasu T., Gal C., Gallus P., Garg P., Garishvili I., Ge H., Giordano F., Glenn A., Gong X., Gonin M., Goto Y., de Cassagnac C. R. G., Grau N., Greene S. V., Perdekamp M. G., Gu Y., Gunji T., Guo L., Guragain H., Gustafsson H. -., Hachiya T., Haggerty J. S., Hahn K. I., Hamagaki H., Hamblen J., Han R., Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical Review D. 90, 5, 052002.  Abstract

   The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low-mass vector-meson, ω, ρ, and φ, production through the dimuon decay channel at forward rapidity (1.2

   [All authors]
10. Inclusive double-helicity asymmetries in neutral-pion and eta-meson production in +collisions at root s=200 GeV

    Adare A., Aidala C., Ajitanand N. N., Akiba Y., Akimoto R., Al-Ta'ani H., Alexander J., Andrews K. R., Angerami A., Aoki K., Apadula N., Appelt E., Aramaki Y., Armendariz R., Aschenauer E. C., Awes T. C., Azmoun B., Babintsev V., Bai M., Bannier B., Barish K. N., Bassalleck B., Basye A. T., Bathe S., Baublis V., Baumann C., Bazilevsky A., Belmont R., Ben-Benjamin J., Bennett R., Blau D. S., Bok J. S., Boyle K., Brooks M. L., Broxmeyer D., Buesching H., Bumazhnov V., Bunce G., Butsyk S., Campbell S., Castera P., Chen C. -., Chi C. Y., Chiu M., Choi I. J., Choi J. B., Choudhury R. K., Christiansen P., Chujo T., Chvala O., Cianciolo V., Citron Z. H., Cole B. A., Del Valle V. Z. C., Connors M., Csanad M., Csoergo T., Dairaku S., Datta A., David G., Dayananda M. K., Denisov A., Deshpande A., Desmond E. J., Dharmawardane K. V., Dietzsch O., Dion A., Donadelli M., Drapier O., Drees A., Drees K. A., Durham J. M., Durum A., D'Orazio L., Efremenko Y. V., Engelmore T., Enokizono A., En'yo H., Esumi S., Fadem B., Fields D. E., Finger M., Finger M. J., Fleuret F., Fokin S. L., Frantz J. E., Franz A., Frawley A. D., Fukao Y., Fusayasu T., Gal C., Garishvili I., Giordano F., Glenn A., Gong X., Gonin M., Goto Y., de Cassagnac C. R. G., Grau N., Greene S. V., Perdekamp M. G., Gunji T., Guo L., Gustafsson H. -., Haggerty J. S., Hahn K. I., Hamagaki H., Hamblen J., Han R., Hanks J., Harper C., Hashimoto K., Haslum E., Hayano R., He X., Hemmick T. K., Hester T., Hill J. C., Hollis R. S., Holzmann W., Homma K., Hong B., Horaguchi T., Hori Y., Hornback D., Huang J., Huang S. -. J., Ichihara T., Ichimiya R., Iinuma H., Ikeda Y., Imai K., Inaba M., Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical Review D. 90, 1, 012007.  Abstract

    Results are presented from data recorded in 2009 by the PHENIX experiment at the Relativistic Heavy Ion Collider for the double-longitudinal spin asymmetry, ALL, for π0 and η production in s=200GeV polarized p+p collisions. Comparison of the π0 results with different theory expectations based on fits of other published data showed a preference for small positive values of gluon polarization, ΔG, in the proton in the probed Bjorken x range. The effect of adding the new 2009 π0 data to a recent global analysis of polarized scattering data is also shown, resulting in a best fit value ΔGDSSV[0.05,0.2]=0.06-0.15+0.11 in the range 0.05

    [All authors]
11. Measurement of transverse-single-spin asymmetries for midrapidity and forward-rapidity production of hadrons in polarized p+p collisions at √s=200 and 62.4 GeV

    Adare A., Afanasiev S., Aidala C., Ajitanand N. N., Akiba Y., Al-Bataineh H., Alexander J., Angerami A., Aoki K., Apadula N., Aphecetche L., Aramaki Y., Asai J., Citron Z. H., Fraenkel Z., Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical Review D. 90, 1, 012006.  Abstract

    Measurements of transverse-single-spin asymmetries (AN) in p+p collisions at s=62.4 and 200 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider are presented. At midrapidity, AN is measured for neutral pion and eta mesons reconstructed from diphoton decay, and, at forward rapidities, neutral pions are measured using both diphotons and electromagnetic clusters. The neutral-pion measurement of AN at midrapidity is consistent with zero with uncertainties a factor of 20 smaller than previous publications, which will lead to improved constraints on the gluon Sivers function. At higher rapidities, where the valence quark distributions are probed, the data exhibit sizable asymmetries. In comparison with previous measurements in this kinematic region, the new data extend the kinematic coverage in s and pT, and it is found that the asymmetries depend only weakly on s. The origin of the forward AN is presently not understood quantitatively. The extended reach to higher pT probes the transition between transverse momentum dependent effects at low pT and multiparton dynamics at high pT.

    [All authors]
12. Cold-nuclear-matter effects on heavy-quark production at forward and backward rapidity in d+Au collisions at sNN =200GeV

    Adare A., Aidala C., Ajitanand N. N., Akiba Y., Akimoto R., Al-Bataineh H., Al-Ta'ani H., Alexander J., Andrews K. R., Angerami A., Aoki K., Apadula N., Appelt E., Aramaki Y., Armendariz R., Aschenauer E. C., Atomssa E. T., Averbeck R., Awes T. C., Azmoun B., Babintsev V., Bai M., Baksay G., Baksay L., Bannier B., Barish K. N., Bassalleck B., Basye A. T., Bathe S., Baublis V., Baumann C., Bazilevsky A., Belikov S., Belmont R., Ben-Benjamin J., Bennett R., Bhom J. H., Blau D. S., Bok J. S., Boyle K., Brooks M. L., Broxmeyer D., Buesching H., Bumazhnov V., Bunce G., Butsyk S., Campbell S., Caringi A., Castera P., Chen C. -., Chi C. Y., Chiu M., Choi I. J., Choi J. B., Choudhury R. K., Christiansen P., Chujo T., Chung P., Chvala O., Cianciolo V., Citron Z. H., Cole B. A., del Valle V. Z. C., Connors M., Csanad M., Csorgo T., Dahms T., Dairaku S., Danchev I., Das K., Datta A., David G., Dayananda M. K., Denisov A., Deshpande A., Desmond E. J., Dharmawardane K. V., Dietzsch O., Dion A., Donadelli M., Drapier O., Drees A., Drees K. A., Durham J. M., Durum A., Dutta D., D'Orazio L., Edwards S., Efremenko Y. V., Ellinghaus F., Engelmore T., Enokizono A., En'yo H., Esumi S., Fadem B., Fields D. E., Finger M., Finger M. J., Fleuret F., Fokin S. L., Fraenkel Z., Frantz J. E., Franz A., Frawley A. D., Fujiwara K., Fukao Y., Fusayasu T., Gal C., Garishvili I., Glenn A., Gong H., Gong X., Gonin M., Goto Y., de Cassagnac C. R. G., Grau N., Greene S. V., Grim G., Perdekamp M. G., Gunji T., Guo L., Gustafsson H. -., Haggerty J. S., Hahn K. I., Hamagaki H., Hamblen J., Han R., Hanks J., Harper C., Hashimoto K., Haslum E., Hayano R., Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical review letters. 112, 25, 252301.  Abstract

    The PHENIX experiment has measured open heavy-flavor production via semileptonic decay over the transverse momentum range 1

    [All authors]
13. Transverse-energy distributions at midrapidity in p+p, d+Au, and Au+Au collisions at s NN =62.4 -200 GeV and implications for particle-production models

    Adler S. S., Afanasiev S., Aidala C., Ajitanand N. N., Akiba Y., Al-Jamel A., Alexander J., Aoki K., Aphecetche L., Armendariz R., Aronson S. H., Averbeck R., Awes T. C., Azmoun B., Babintsev V., Baldisseri A., Barish K. N., Barnes P. D., Bassalleck B., Bathe S., Batsouli S., Baublis V., Bauer F., Bazilevsky A., Belikov S., Bennett R., Berdnikov Y., Bjorndal M. T., Boissevain J. G., Borel H., Boyle K., Brooks M. L., Brown D. S., Bruner N., Bucher D., Buesching H., Bumazhnov V., Bunce G., Burward-Hoy J. M., Butsyk S., Camard X., Campbell S., Chai J. -., Chand P., Chang W. C., Chernichenko S., Chi C. Y., Chiba J., Chiu M., Choi I. J., Choudhury R. K., Chujo T., Cianciolo V., Cleven C. R., Cobigo Y., Cole B. A., Comets M. P., Constantin P., Csanad M., Csoergo T., Cussonneau J. P., Dahms T., Das K., David G., Deak F., Delagrange H., Denisov A., d'Enterria D., Deshpande A., Desmond J., Devismes A., Dietzsch O., Dion A., Drachenberg J. L., Drapier O., Drees A., Durum A., Dutta D., Dzhordzhadze V., Efremenko Y. V., Egdemir J., Enokizono A., En'yo H., Espagnon B., Esumi S., Fields D. E., Finck C., Fleuret F., Fokin S. L., Forestier B., Fox B. D., Fraenkel Z., Frantz J. E., Franz A., Frawley A. D., Fukao Y., Fung S. -., Gadrat S., Gastineau F., Germain M., Glenn A., Gonin M., Gosset J., Goto Y., de Cassagnac C. R. G., Grau N., Greene S. V., Perdekamp M. G., Gunji T., Gustafsson H. -., Hachiya T., Henni A. H., Haggerty J. S., Hagiwara M. N., Hamagaki H., Hansen A. G., Harada H., Hartouni E. P., Haruna K., Harvey M., Haslum E., Hasuko K., Hayano R., He X., Heffner M., Hemmick T. K., Heuser J. M., Hidas P., Hiejima H., Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical Review C. 89, 4, 044905.  Abstract

    Measurements of the midrapidity transverse-energy distribution, dET/dη, are presented for p+p, d+Au, and Au+Au collisions at sNN=200 GeV and additionally for Au+Au collisions at sNN=62.4 and 130 GeV. The dET/dη distributions are first compared with the number of nucleon participants Npart, number of binary collisions Ncoll, and number of constituent-quark participants Nqp calculated from a Glauber model based on the nuclear geometry. For Au+Au, dET/d/Npart increases with Npart, while dET/d/Nqp is approximately constant for all three energies. This indicates that the two-component ansatz, dET/d (1-x)Npart/2+xNcoll, which was used to represent ET distributions, is simply a proxy for Nqp, and that the Ncoll term does not represent a hard-scattering component in ET distributions. The dET/dη distributions of Au+Au and d+Au are then calculated from the measured p+p ET distribution using two models that both reproduce the Au+Au data. However, while the number-of-constituent-quark- participant model agrees well with the d+Au data, the additive-quark model does not.

    [All authors]
14. Heavy-flavor electron-muon correlations in p+p and d+Au collisions at sNN =200 GeV

    Adare A., Afanasiev S., Aidala C., Ajitanand N. N., Akiba Y., Al-Bataineh H., Alexander J., Angerami A., Aoki K., Apadula N., Aphecetche L., Aramaki Y., Asai J., Atomssa E. T., Averbeck R., Awes T. C., Azmoun B., Babintsev V., Bai M., Baksay G., Baksay L., Baldisseri A., Barish K. N., Barnes P. D., Bassalleck B., Basye A. T., Bathe S., Batsouli S., Baublis V., Baumann C., Bazilevsky A., Belikov S., Belmont R., Bennett R., Berdnikov A., Berdnikov Y., Bhom J. H., Bickley A. A., Blau D. S., Boissevain J. G., Bok J. S., Borel H., Boyle K., Brooks M. L., Buesching H., Bumazhnov V., Bunce G., Butsyk S., Camacho C. M., Campbell S., Caringi A., Chang B. S., Chang W. C., Charvet J. -., Chen C. -., Chernichenko S., Chi C. Y., Chiu M., Choi I. J., Choi J. B., Choudhury R. K., Christiansen P., Chujo T., Chung P., Churyn A., Chvala O., Cianciolo V., Citron Z. H., Cole B. A., del Valle V. Z. C., Connors M., Constantin P., Csanad M., Csoergo T., Dahms T., Dairaku S., Danchev I., Das K., Datta A., David G., Dayananda M. K., Denisov A., d'Enterria D., Deshpande A., Desmond E. J., Dharmawardane K. V., Dietzsch O., Dion A., Donadelli M., Drapier O., Drees A., Drees K. A., Durham J. M., Durum A., Dutta D., Dzhordzhadze V., D'Orazio L., Edwards S., Efremenko Y. V., Ellinghaus F., Engelmore T., Enokizono A., En'yo H., Esumi S., Eyser K. O., Fadem B., Fields D. E., Finger M., Finger M. J., Fleuret F., Fokin S. L., Fraenkel Z., Frantz J. E., Franz A., Frawley A. D., Fujiwara K., Fukao Y., Fusayasu T., Garishvili I., Glenn A., Gong H., Gonin M., Gosset J., Goto Y., de Cassagnac C. R. G., Grau N., Greene S. V., Grim G., Perdekamp M. G., Dubey A. K., Makek M., Milov A., Sharma D., Tserruya I. et al. (2014) Physical Review C. 89, 3, 034915.  Abstract

    Background: Heavy-flavor modification in relativistic p(d)+A collisions are sensitive to different kinds of strong-interaction physics ranging from modifications of the nuclear wave function to initial- and final-state energy loss. Modifications to single heavy-flavor particles and their decay leptons at midrapidity and forward rapidity are well established at the Relativistic Heavy Ion Collider (RHIC). Purpose: This paper presents measurements of azimuthal correlations of electron-muon pairs produced from heavy-flavor decays, primarily cc̄, in sNN=200 GeV p+p and d+Au collision using the PHENIX detector at RHIC. The electrons are measured at midrapidity while the muons in the pair are measured at forward rapidity, defined as the direction of the deuteron beam, in order to utilize the deuteron to probe low-x partons in the gold nucleus. Methods: This analysis uses the central spectrometer arms for electron identification and forward spectrometer arms for muon identification. Azimuthal correlations are built in all sign combinations for e-μ pairs. Subtracting the like-sign yield from the unlike-sign yield removes the correlations from light flavor decays and conversions. Results: Comparing the p+p results with several different Monte Carlo event generators, we find the results are consistent with a total charm cross section σcc̄=538±46 (stat) ± 197 (data syst) ± 174 (model syst) μb. These generators also indicate that the back-to-back peak at Δφ=π is dominantly from the leading-order contributions (gluon fusion), while higher-order processes (flavor excitation and gluon splitting) contribute to the yield at all Δφ. We observe a suppression in the pair yield per collision in d+Au. We find the pair yield suppression factor for 2.7

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