Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session Y11: Particle Production in d-Au Collisions |
Hide Abstracts |
Sponsoring Units: DNP Chair: C.L. da Silva, Iowa State University Room: Maryland C |
Tuesday, February 16, 2010 1:30PM - 1:42PM |
Y11.00001: R$_{dA}$ of $\pi^{0}$ and $\gamma$ in d+Au collisions at 200 GeV by the PHENIX experiment at RHIC using year 2008 data Ondrej Chvala Previous results [1,2] indicated that high $p_T$ particle suppression in Au+Au interactions is a final state effect, since R$_{dA}$ ratios were compatible with unity, albeit within large experimental errors. It is important to test the lack of cold matter effects to higher precision since the modification of structure functions themselves may be involved. Recent d+Au data taken in 2008 improve the total integrated luminosity of the 2003 data sample by more than a factor of twenty. The joint behavior of $\pi^{0}$ and $\gamma$ at higher $p_T$ will shed new light on whether the initial (Au) state is modified. The current status of these analyses with the 2008 data set will be shown. \\[4pt] [1] S. S. Adler et al. [PHENIX Collaboration], Phys. Rev. Lett. 98, 172302 (2007) [arXiv:nuclex/0610036].\\[0pt] [2] D. Peressounko [PHENIX Collaboration], Nucl. Phys. A 783, 577 (2007) [arXiv:hepex/0609037]. [Preview Abstract] |
Tuesday, February 16, 2010 1:42PM - 1:54PM |
Y11.00002: Measurement of Forward Azimuthal Di-Hadron Correlations in d+Au Collisions with the PHENIX Detector at RHIC Beau Meredith Deuteron-gold collisions at RHIC provide a system wherein one can explore nuclear effects on initial-state parton densities in the absence of final-state medium effects. RHIC experiments have shown a suppression in nuclear modification factors ($R_{dA}$, $R_{cp}$) for $\sqrt{s_{NN}} = 200$ GeV d+Au collisions in the forward (deuteron) direction and an enhancement in the backward (gold) direction. Multiple theories exist that can explain the observed suppression and enhancement, but a conclusive measurement discriminating between the different mechanisms has yet to be carried out. Two forward electromagnetic calorimeters (Muon Piston Calorimeters or MPCs, $-3.7 < \eta < -3.1$, $3.1<\eta<3.9$) allow PHENIX to study parton densities at low $x$. Azimuthal correlations of di-hadron pairs at different pseudorapidities will be shown; the forward pseudorapidity correlations are especially interesting because it is expected that they provide a test of gluon saturation at low x in the Au nucleus. The analysis presented is based on the high integrated luminosity data sample of d+Au collisions at $\sqrt{s_{NN}} = 200$ GeV taken at RHIC in 2008. [Preview Abstract] |
Tuesday, February 16, 2010 1:54PM - 2:06PM |
Y11.00003: Cold Nuclear Matter Effects on Jets in PHENIX Nathan Grau In order to understand jet quenching effects in the hot dense matter created in relativistic heavy ion collisions at RHIC, it is necessary to understand the baseline effects that are present. These include effect of nuclear parton distribution functions (nPDFs), shadowing, anti-shadowing, and the EMC effect, and multiple scattering of the partons before and/or after the hard scattering. This physics can be probed using fully reconstructed jets in p+$A$ collisions. We use the PHENIX detector to reconstruct jets using the anti-$k_T$ algorithm in d+$Au$ collisions at $\sqrt{s_{NN}}$ = 200 GeV. We will present the latest results from jet reconstruction in d+$Au$ and discuss the implication for physics in both cold and hot dense nuclear matter. [Preview Abstract] |
Tuesday, February 16, 2010 2:06PM - 2:18PM |
Y11.00004: Electron-Muon Correlations in $p$+$p$ and $d$+Au at PHENIX at $\sqrt{s} = 200$ GeV Tatia Engelmore Heavy quarks are useful in understanding the hot, dense medium created in a heavy ion collision, and are an important test of proposed mechanisms of parton energy loss. In order to study heavy quark production, electron-muon pairs are a valuable measurement because these are produced with a clean signal. PHENIX detects electrons in the central arms ($|\eta|<0.35$) and muons in the forward (1.4$<\eta<$2.1) and backward (-2.1$<\eta<$-1.4) regions, so it is sensitive to heavy quark pairs produced in an intermediate rapidity range. To understand the behavior of $e-\mu$ pairs in the medium, we first need to establish a baseline measurement in $p$+$p$, as well as determine the cold-matter effects in $d$+Au collisions. In $d$+Au, a comparison of the yield of pairs with muons at forward rapidity (small x) to pairs with muons at backward rapidity (large x) could help to better understand gluon saturation and shadowing effects on heavy quarks versus enhancement from antishadowing. Results of $e-\mu$ azimuthal correlations in $p$+$p$ will be reviewed, and update on $e-\mu$ in $d$+Au collisions will be presented. [Preview Abstract] |
Tuesday, February 16, 2010 2:18PM - 2:30PM |
Y11.00005: ABSTRACT WITHDRAWN |
Tuesday, February 16, 2010 2:30PM - 2:42PM |
Y11.00006: $\phi$ meson production and cold nuclear matter effect in $d$+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV in STAR Xiaoping Zhang To understand the properties of the quark-gluon plasma created in heavy ion collisions, one needs knowledge on various cold nuclear matter effects. Some of these effects might be studied by looking into p+A like collisions. Specifically, one has to distinguish the initial state effects and final state effects. Theoretical calculations have shown different rapidity and species dependence of particle production if the final state interactions are dominated by different later-stage (hadronic or partonic dominated) rescatterings. $\phi$ meson is a heavy meson with mass close to that of light baryons (proton and $\Lambda$) and with small cross sections with other non-strange particles. Thus its measurement is an important probe to distinguish the different later-stage interactions in $d+Au$ collisions and to provide early-time information of the collisions. \ \ \ \ Here we report preliminary results of $\phi$-meson measurements in STAR, via K$^{+}$K$^{-}$ and e$^{+}$e$^{-}$ decays, in 200 GeV $d$+Au collisions. The dataset are from RHIC year 2008 runs with significantly reduced material ($\sim$ 1/10) after removing the inner tracker and high statistics ($\sim$ 3) compared with previous runs of year 2003. $\phi$-meson transverse momentum spectra distribution and its rapidity dependence will be presented and compared with model calculations. Implications on cold nuclear matter effect on particle productions in $d$+Au collisions will be discussed. [Preview Abstract] |
Tuesday, February 16, 2010 2:42PM - 2:54PM |
Y11.00007: Characterizing cold nuclear matter effects through dielectrons in $d$+Au collisions at $\sqrt{s_{NN}} = 200$~GeV at PHENIX Jason Kamin Electron-positron pairs are effective probes for investigating the hot, dense matter created in RHIC collisions because they are color neutral and therefore, once created, do not interact strongly with the medium. As a result, they retain characteristics of the full time evolution and dynamics of the system. Among the many features, the low mass region (m$<$1 GeV/c$^2$) consists primarily of pairs from Dalitz decays of light hadrons and direct decays of vector mesons that can be modified by the medium, while the intermediate (1$<$m$<$3 GeV/c$^2$) and high (4$<$m$<$12 GeV/c$^2$) mass regions are dominated by mesons containing charm and bottom. The PHENIX experiment has presented the dielectron continuum spectrum in $p$+$p$, Cu+Cu and Au+Au collisions at $\sqrt{s_{NN}} = 200$~GeV. An enhancement is observed in Au+Au in the mass range 150$<$m$<$750 MeV/c$^2$ when compared to the expected hadronic sources. This enhancement is not seen in $p$+$p$ collisions. Recently PHENIX measured $d$+Au collisions which are crucial as they provide a complimentary reference for comparison with heavy ion collisions and can identify potential initial state effects contributing to the low-mass excess seen in Au+Au. The statistics also allow the $d$+Au measurement to extend to mass ranges where bottom dominates. These data are being analyzed and the $d$+Au dielectron status will be presented. [Preview Abstract] |
Tuesday, February 16, 2010 2:54PM - 3:06PM |
Y11.00008: Gluon Modifications and Asymmetric Light-on-Heavy Nuclear Collisions Adeola Adeluyi, Trang Nguyen, Bao-An Li Observables such as nuclear modification factor and pseudorapidity asymmetry in p(d)A collisions are useful in constraining global fits to nuclear parton distributions. Using the framework of perturbative Quantum Chromodynamics (pQCD) we investigate the sensitivity of these observables to nuclear gluon modifications at RHIC (d+Au) and LHC (p+Pb) energies. [Preview Abstract] |
Tuesday, February 16, 2010 3:06PM - 3:18PM |
Y11.00009: Nuclear modification factors for low mass vector meson production in $d$+Au collisions at 200 GeV over the forward and backward rapidity Lei Guo In $d$+Au collisions, vector mesons produced in hard scattering are sensitive to various nuclear effects such as parton distribution modifications of the nucleons in nucleus, including shadowing/saturation leading to a gluon suppression at forward rapidity (small x), and anti-shadowing that enhances the number of partons at backward rapidity (large x), as well as the Cronin effect. Since approaches such as the Color Glass Condensate (CGC) and pQCD-based Glauber-Eikonal models do not agree on the nature of these nuclear effects on particle production at forward rapidity, it is essential that they be tested with experimental data in this kinematic regime. Knowledge of the difference between the particle production in the forward and backward rapidity, in $d$+Au collisions, could also be used to separate the initial-state nuclear wave function modifications and final state in-medium effects in Au+Au collisions. The PHENIX collaboration at RHIC has recently collected data in $d$+Au collisions at $\sqrt{s}$=200~GeV during the 2008 run. Preliminary results of the nuclear modification factor measurements of $\phi, \rho$, and $\omega$, through the di-muon decays at forward (1.2$< \eta <$2.4) and backward (-2.4$< \eta <$-1.2) rapidity will be shown. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700