New Insights into White-Light Flare Emission from Radiative-Hydrodynamic Modeling of a Chromospheric Condensation

(abridged) The heating mechanism at high densities during M dwarf flares is poorly understood. Spectra of M dwarf flares in the optical and near-ultraviolet wavelength regimes have revealed three continuum components during the impulsive phase: 1) an energetically dominant blackbody component with a color temperature of T $\sim$ 10,000 K in the blue-optical, 2) a smaller amount of Balmer continuum emission in the near-ultraviolet at lambda $<$ 3646 Angstroms and 3) an apparent pseudo-continuum of blended high-order Balmer lines. These properties are not reproduced by models that employ a typical "solar-type" flare heating level in nonthermal electrons, and therefore our understanding of these spectra is limited to a phenomenological interpretation. We present a new 1D radiative-hydrodynamic model of an M dwarf flare from precipitating nonthermal electrons with a large energy flux of $10^{13}$ erg cm$^{-2}$ s$^{-1}$. The simulation produces bright continuum emission from a dense, hot chromospheric condensation. For the first time, the observed color temperature and Balmer jump ratio are produced self-consistently in a radiative-hydrodynamic flare model. We find that a T $\sim$ 10,000 K blackbody-like continuum component and a small Balmer jump ratio result from optically thick Balmer and Paschen recombination radiation, and thus the properties of the flux spectrum are caused by blue light escaping over a larger physical depth range compared to red and near-ultraviolet light. To model the near-ultraviolet pseudo-continuum previously attributed to overlapping Balmer lines, we include the extra Balmer continuum opacity from Landau-Zener transitions that result from merged, high order energy levels of hydrogen in a dense, partially ionized atmosphere. This reveals a new diagnostic of ambient charge density in the densest regions of the atmosphere that are heated during dMe and solar flares.Comment: 50 pages, 2 tables, 13 figures. Accepted for publication in the Solar Physics Topical Issue, "Solar and Stellar Flares". Version 2 (June 22, 2015): updated to include comments by Guest Editor. The final publication is available at Springer via http://dx.doi.org/10.1007/s11207-015-0708-

Imaging Observations of Quasi-Periodic Pulsatory Non-Thermal Emission in Ribbon Solar Flares

Using RHESSI and some auxiliary observations we examine possible connections between spatial and temporal morphology of the sources of non-thermal hard X-ray (HXR) emission which revealed minute quasi-periodic pulsations (QPPs) during the two-ribbon flares on 2003 May 29 and 2005 January 19. Microwave emission also reveals the same quasi-periodicity. The sources of non-thermal HXR emission are situated mainly inside the footpoints of the flare arcade loops observed by the TRACE and SOHO instruments. At least one of the sources moves systematically both during the QPP-phase and after it in each flare that allows to examine the sources velocities and the energy release rate via the process of magnetic reconnection. The sources move predominantly parallel to the magnetic inversion line or the appropriate flare ribbon during the QPP-phase whereas the movement slightly changes to more perpendicular regime after the QPPs. Each QPP is emitted from its own position. It is also seen that the velocity and the energy release rate don't correlate well with the flux of the HXR emission calculated from the sources. The sources of microwaves and thermal HXRs are situated near the apex of the loop arcade and are not stationary either. Almost all QPPs and some spikes of HXR emission during the post-QPP-phase reveal the soft-hard-soft spectral behavior indicating separate acts of electrons acceleration and injection, rather than modulation of emission flux by some kinds of magnetohydrodynamic (MHD) oscillations of coronal loops. In all likelihood, the flare scenarios based on the successively firing arcade loops are more preferable to interpret the observations, although we can not conclude exactly what mechanism forces these loops to flare up.Comment: 22 pages, 10 figure

Effect of event selection on jetlike correlation measurement in d+Au collisions at sNN=200 GeV

AbstractDihadron correlations are analyzed in sNN=200 GeV d+Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions

J/ψ polarization in p+p collisions at s=200 GeV in STAR

AbstractWe report on a polarization measurement of inclusive J/ψ mesons in the di-electron decay channel at mid-rapidity at 2<pT<6 GeV/c in p+p collisions at s=200 GeV. Data were taken with the STAR detector at RHIC. The J/ψ polarization measurement should help to distinguish between different models of the J/ψ production mechanism since they predict different pT dependences of the J/ψ polarization. In this analysis, J/ψ polarization is studied in the helicity frame. The polarization parameter λθ measured at RHIC becomes smaller towards high pT, indicating more longitudinal J/ψ polarization as pT increases. The result is compared with predictions of presently available models

Beam-energy Dependence Of Charge Balance Functions From Au + Au Collisions At Energies Available At The Bnl Relativistic Heavy Ion Collider

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Balance functions have been measured in terms of relative pseudorapidity (Δη) for charged particle pairs at the BNL Relativistic Heavy Ion Collider from Au + Au collisions at sNN=7.7GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at sNN=2.76TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing of the balance function in central collisions at sNN=7.7 GeV implies that a QGP is still being created at this relatively low energy. © 2016 American Physical Society.942CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoMinistry of Education and Science of the Russian FederationMOE, Ministry of Education of the People's Republic of ChinaMOST, Ministry of Science and Technology of the People's Republic of ChinaNRF-2012004024, National Research FoundationNSF, National Stroke FoundationConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Dielectron Azimuthal Anisotropy At Mid-rapidity In Au+au Collisions At Snn =200 Gev

We report on the first measurement of the azimuthal anisotropy (v2) of dielectrons (e+e- pairs) at mid-rapidity from sNN=200 GeV Au+Au collisions with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), presented as a function of transverse momentum (pT) for different invariant-mass regions. In the mass region Mee<1.1 GeV/c2 the dielectron v2 measurements are found to be consistent with expectations from π0,η,ω, and φ decay contributions. In the mass region 1.1<Mee<2.9GeV/c2, the measured dielectron v2 is consistent, within experimental uncertainties, with that from the cc¯ contributions.906Adams, J., (2005) Nucl. Phys. A, 757, p. 102. , NUPABL 0375-9474Arsene, I., (2005) Nucl. Phys. A, 757, p. 1. , NUPABL 0375-9474Adcox, K., (2005) Nucl. Phys. A, 757, p. 184. , NUPABL 0375-9474Back, B.B., (2005) Nucl. Phys. A, 757, p. 28. , NUPABL 0375-9474Rapp, R., Wambach, J., (2002) Adv. Nucl. Phys., 25, p. 1. , 0065-2970David, G., Rapp, R., Xu, Z., (2008) Phys. Rep., 462, p. 176. , PRPLCM 0370-1573Agakichiev, G., (2005) Eur. Phys. J. C, 41, p. 475. , EPCFFB 1434-6044Arnaldi, R., (2006) Phys. Rev. Lett., 96, p. 162302. , PRLTAO 0031-9007Brown, G.E., Rho, M., (1996) Phys. Rep., 269, p. 333. , PRPLCM 0370-1573Rapp, R., Wambach, J., (1999) Eur. Phys. J. A, 6, p. 415. , EPJAFV 1434-6001Dusling, K., Teaney, D., Zahed, I., (2007) Phys. Rev. C, 75, p. 024908. , PRVCAN 0556-2813Van Hees, H., Rapp, R., (2008) Nucl. Phys. A, 806, p. 339. , NUPABL 0375-9474Renk, T., Ruppert, J., (2008) Phys. Rev. C, 77, p. 024907. , PRVCAN 0556-2813Adare, A., (2010) Phys. Rev. C, 81, p. 034911. , PRVCAN 0556-2813Adamczyk, L., (2014) Phys. Rev. Lett., 113, p. 022301. , a longer version (unpublished). PRLTAO 0031-9007Rapp, R., Wambach, J., Van Hees, H., (2010) Relativistic Heavy-Ion Physics, , in, edited by R. Stock, Landolt Börnstein New Series I/23A (Springer, Berlin), Chap. 4-1Linnyk, O., Cassing, W., Manninen, J., Bratkovskaya, E.L., Ko, C.M., (2012) Phys. Rev. C, 85, p. 024910. , PRVCAN 0556-2813Xu, J.-H., Chen, H.F., Dong, X., Wang, Q., Zhang, Y.F., (2012) Phys. Rev. C, 85, p. 024906. , PRVCAN 0556-2813Adare, A., (2010) Phys. Rev. Lett., 104, p. 132301. , PRLTAO 0031-9007Poskanzer, A.M., Voloshin, S.A., (1998) Phys. Rev. C, 58, p. 1671. , PRVCAN 0556-2813Adare, A., (2012) Phys. Rev. Lett., 109, p. 122302. , PRLTAO 0031-9007Van Hees, H., Gale, C., Rapp, R., (2011) Phys. Rev. C, 84, p. 054906. , PRVCAN 0556-2813Chatterjee, R., Srivastava, D.K., Heinz, U., Gale, C., (2007) Phys. Rev. C, 75, p. 054909. , PRVCAN 0556-2813Adare, A., (2009) Phys. Lett. B, 670, p. 313. , PYLBAJ 0370-2693Bonner, B., (2003) Nucl. Instrum. Methods A, 508, p. 181. , NIMAER 0168-9002Shao, M., (2002) Nucl. Instrum. Methods A, 492, p. 344Wu, J., (2005) Nucl. Instrum. Methods A, 538, p. 243. , NIMAER 0168-9002Landgraf, J.M., (2003) Nucl. Instrum. Methods A, 499, p. 762. , NIMAER 0168-9002Ackermann, K.H., (2003) Nucl. Instrum. Methods A, 499, p. 624. , NIMAER 0168-9002Anderson, M., (2003) Nucl. Instrum. Methods A, 499, p. 659. , NIMAER 0168-9002Bichsel, H., (2006) Nucl. Instrum. Methods A, 562, p. 154. , NIMAER 0168-9002Xu, Y., (2010) Nucl. Instrum. Methods A, 614, p. 28. , NIMAER 0168-9002Shao, M., (2006) Nucl. Instrum. Methods A, 558, p. 419. , NIMAER 0168-9002Adams, J., (2005) Phys. Lett. B, 616, p. 8. , PYLBAJ 0370-2693Ruan, L., Ph.D. thesis, University of Science and Technology of China, 2005, arXiv:nucl-ex/0503018 (unpublished)Llope, W.J., (2004) Nucl. Instrum. Methods A, 522, p. 252. , NIMAER 0168-9002Adler, C., (2002) Phys. Rev. Lett., 89, p. 202301. , PRLTAO 0031-9007Adams, J., (2005) Phys. Rev. Lett., 94, p. 062301. , PRLTAO 0031-9007Adamczyk, L., (2012) Phys. Rev. C, 86, p. 024906. , PRVCAN 0556-2813Zhao, J., (2013), https://drupal.star.bnl.gov/STAR/theses/phd-32, Ph.D. thesis, Shanghai Institute of Applied Physics, (unpublished)Voloshin, S.A., Poskanzer, A.M., Snellings, R., (2010) Relativistic Heavy Ion Physics, pp. 5-54. , in, Landolt-Börnstein Vol. 1/23 (Springer-Verlag, Berlin), ppAdamczyk, L., (2013) Phys. Rev. C, 88, p. 014902. , PRVCAN 0556-2813Abelev, B.I., (2008) Phys. Rev. C, 77, p. 054901. , PRVCAN 0556-2813Abelev, B.I., (2006) Phys. Rev. Lett., 97, p. 152301. , PRLTAO 0031-9007Abelev, B.I., (2009) Phys. Rev. C, 79, p. 034909. , PRVCAN 0556-2813Abelev, B.I., (2009) Phys. Rev. C, 79, p. 064903. , PRVCAN 0556-2813Adams, J., (2005) Phys. Lett. B, 612, p. 181. , PYLBAJ 0370-2693Adler, S.S., (2007) Phys. Rev. C, 75, p. 024909. , PRVCAN 0556-2813Tang, Z., Xu, Y., Ruan, L., Van Buren, G., Wang, F., Xu, Z., (2009) Phys. Rev. C, 79, p. 051901. , (R) () PRVCAN 0556-2813Shao, M., Yi, L., Tang, Z., Chen, H., Li, C., Xu, Z., (2010) J. Phys. G, 37, p. 085104. , JPGPED 0954-3899Afanasiev, S., (2009) Phys. Rev. C, 80, p. 054907. , PRVCAN 0556-2813Adams, J., (2005) Phys. Rev. C, 72, p. 014904. , PRVCAN 0556-2813Abelev, B.I., (2007) Phys. Rev. Lett., 99, p. 112301. , PRLTAO 0031-9007Kroll, N.M., Wada, W., (1955) Phys. Rev., 98, p. 1355. , PHRVAO 0031-899XRuan, L., (2011) Nucl. Phys. A, 855, p. 269. , NUPABL 0375-9474Huang, B., (2011), Ph.D. thesis, University of Science and Technology of China, (unpublished)Sjöstrand, T., (2001) Comput. Phys. Commun., 135, p. 238. , CPHCBZ 0010-4655Adamczyk, L., (2012) Phys. Rev. D, 86, p. 072013. , PRVDAQ 1550-7998Agakishiev, H., (2011) Phys. Rev. D, 83, p. 052006. , PRVDAQ 1550-7998Adare, A., (2011) Phys. Rev. C, 84, p. 044905. , PRVCAN 0556-2813Adare, A., (2012) Phys. Rev. C, 85, p. 064914. , PRVCAN 0556-2813Adare, A., (2007) Phys. Rev. Lett., 98, p. 162301. , PRLTAO 0031-9007Adams, J., (2004) Phys. Rev. Lett., 92, p. 052302. , PRLTAO 0031-9007Vujanovic, G., Young, C., Schenke, B., Jeon, S., Rapp, R., Gale, C., (2013) Nucl. Phys. A, 904-905, p. 557c. , NUPABL 0375-9474Vujanovic, G., Young, C., Schenke, B., Jeon, S., Rapp, R., Gale, C., (2014) Phys. Rev. C, 89, p. 034904. , PRVCAN 0556-281

J/ψ Production At Low Pt In Au+au And Cu+cu Collisions At Snn =200 Gev With The Star Detector

The J/ψ pT spectrum and nuclear modification factor (RAA) are reported for pT<5GeV/c and |y|<1 from 0% to 60% central Au+Au and Cu+Cu collisions at sNN=200GeV at STAR. A significant suppression of pT-integrated J/ψ production is observed in central Au+Au events. The Cu+Cu data are consistent with no suppression, although the precision is limited by the available statistics. RAA in Au+Au collisions exhibits a strong suppression at low transverse momentum and gradually increases with pT. The data are compared to high-pT STAR results and previously published BNL Relativistic Heavy Ion Collider results. Comparing with model calculations, it is found that the invariant yields at low pT are significantly above hydrodynamic flow predictions but are consistent with models that include color screening and regeneration. © 2014 American Physical Society.902CNRS/IN2P3; NSF; Arthritis National Research Foundation; NRF-2012004024; ANRF; Arthritis National Research FoundationMatsui, T., Satz, H., (1986) Phys Lett. B, 178, p. 416. , PYLBAJ 0370-2693 10.1016/0370-2693(86)91404-8Digal, S., Petreczky, P., Satz, H., (2001) Phys. Rev. D, 64, p. 094015. , 0556-2821 10.1103/PhysRevD.64.094015Karsch, F., Kharzeev, D., Satz, H., Sequential charmonium dissociation (2006) Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 637 (1-2), pp. 75-80. , DOI 10.1016/j.physletb.2006.03.078, PII S037026930600445XBraun-Munzinger, P., Stachel, J., The quest for the quark-gluon plasma (2007) Nature, 448 (7151), pp. 302-309. , DOI 10.1038/nature06080, PII NATURE06080Abreu, M.C., (1999) Phys. Lett. B, 449, p. 128. , (NA38 Collaboration),. PYLBAJ 0370-2693 10.1016/S0370-2693(99)00057-XAbreu, M.C., (1997) Phys. Lett. B, 410, p. 327. , (NA50 Collaboration),. PYLBAJ 0370-2693 10.1016/S0370-2693(97)00914-3Arnaldi, R., Banicz, K., Castor, J., Chaurand, B., Cicalo, C., Colla, A., Cortese, P., Wohri, H.K., J/ψ production in indium-indium collisions at 158GeV/nucleon (2007) Physical Review Letters, 99 (13), p. 132302. , http://oai.aps.org/oai?verb=GetRecord&Identifier=oai:aps.org: PhysRevLett.99.132302&metadataPrefix=oai_apsmeta_2, DOI 10.1103/PhysRevLett.99.132302Adare, A., Afanasiev, S., Aidala, C., Ajitanand, N.N., Akiba, Y., Al-Bataineh, H., Alexander, J., Al-Jamel, A., J/ψ production versus centrality, transverse momentum, and rapidity in Au+Au collisions at s NN=200 GeV (2007) Physical Review Letters, 98 (23), p. 232301. , http://oai.aps.org/oai?verb=GetRecord&Identifier=oai:aps.org: PhysRevLett.98.232301&metadataPrefix=oai_apsmeta_2, DOI 10.1103/PhysRevLett.98.232301Adamczyk, L., (2013) Phys. Lett. B, 722, p. 55. , (STAR Collaboration),. PYLBAJ 0370-2693 10.1016/j.physletb.2013.04.010Abelev, B., (2012) Phys. Rev. Lett., 109, p. 072301. , (ALICE Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.109.072301Chatrchyan, S., (2012) J. High Energy Phys., (5), p. 063. , (CMS Collaboration),. JHEPFG 1029-8479 10.1007/JHEP05(2012)063Braun-Munzinger, P., Stachel, J., (2000) Phys. Lett. B, 490, p. 196. , PYLBAJ 0370-2693 10.1016/S0370-2693(00)00991-6Grandchamp, L., Rapp, R., (2002) Nucl. Phys. A, 709, p. 415. , NUPABL 0375-9474 10.1016/S0375-9474(02)01027-8Gavin, S., Vogt, R., (1996) Nucl. Phys. A, 610, p. 442. , NUPABL 0375-9474 10.1016/S0375-9474(96)00376-4Capella, A., (1997) Phys. Lett. B, 393, p. 431. , PYLBAJ 0370-2693 10.1016/S0370-2693(96)01650-4Karsch, F., Petronzio, P., (1988) Z. Phys. C, 37, p. 627. , ZPCFD2 0170-9739 10.1007/BF01549724Adare, A., (2012) Phys. Rev. D, 85, p. 092004. , (PHENIX Collaboration),. 10.1103/PhysRevD.85.092004Charm, beauty and charmonium production at HERA-B (2005) European Physical Journal C, 43 (1-4), pp. 179-186. , DOI 10.1140/epjc/s2005-02308-8Vogt, R., Shadowing and absorption effects on J/ψ production in da collisions (2005) Physical Review C - Nuclear Physics, 71 (5), pp. 1-11. , http://oai.aps.org/oai/?verb=ListRecords&metadataPrefix= oai_apsmeta_2&set=journal:PRC:71, DOI 10.1103/PhysRevC.71.054902, 054902Gavin, S., Gyulassy, M., (1988) Phys. Lett. B, 214, p. 241. , PYLBAJ 0370-2693 10.1016/0370-2693(88)91476-1Noble, J.V., (1981) Phys. Rev. Lett., 46, p. 412. , PRLTAO 0031-9007 10.1103/PhysRevLett.46.412Tram, V., Arleo, F., (2009) Eur. Phys. J. C, 61, p. 847. , EPCFFB 1434-6044 10.1140/epjc/s10052-009-0864-yAlde, D., Baer, H., Carey, T., Garvey, G., Klein, A., (1991) Phys. Rev. Lett., 66, p. 133. , PRLTAO 0031-9007 10.1103/PhysRevLett.66.133Leitch, M., (1992) Nucl. Phys. A, 544, p. 197. , (E772 and E789 Collaboration),. NUPABL 0375-9474 10.1016/0375-9474(92) 90574-4Leitch, M., (2000) Phys. Rev. Lett., 84, p. 3256. , (NuSea Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.84.3256Alessandro, B., Alexa, C., Arnaldi, R., Atayan, M., Baglin, C., Baldit, A., Beole, S., Willis, N., Charmonium production and nuclear absorption in p-A interactions at 450 GeV (2004) European Physical Journal C, 33 (1), pp. 31-40. , DOI 10.1140/epjc/s2003-01539-yAlessandro, B., Alexa, C., Arnaldi, R., Atayan, M., Beole, S., Boldea, V., Bordalo, P., Wu, T., A new measurement of J/ψ suppression in Pb-Pb collisions at 158 GeV per nucleon (2005) European Physical Journal C, 39 (3), pp. 335-345. , DOI 10.1140/epjc/s2004-02107-9Arnaldi, R., (2012) Phys. Lett. B, 706, p. 263. , (NA60 Collaboration),. PYLBAJ 0370-2693 10.1016/j.physletb.2011.11.042Adare, A., (2013) Phys. Rev. C, 87, p. 034904. , (PHENIX Collaboration),. 10.1103/PhysRevC.87.034904Adare, A., (2013) Phys. Rev. Lett., 111, p. 202301. , (PHENIX Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.111.202301Adare, A., (2011) Phys. Rev. Lett., 107, p. 142301. , (PHENIX Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.107.142301Zhao, X., Rapp, R., (2010) Phys. Rev. C, 82, p. 064905. , PRVCAN 0556-2813 10.1103/PhysRevC.82.064905Adamczyk, L., (2013) Phys. Rev. Lett., 111, p. 052301. , (STAR Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.111.052301Ackermann, K.H., Adams, N., Adler, C., Ahammed, Z., Ahmad, S., Allgower, C., Amonett, J., Harris, J.W., STAR detector overview (2003) Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 499 (2-3), pp. 624-632. , DOI 10.1016/S0168-9002(02)01960-5Llope, W.J., (2004) Nucl. Instrum. Methods Phys. Res., Sect. A, 522, p. 252. , NIMAER 0168-9002 10.1016/j.nima.2003.11.414Adler, C., Denisov, A., Garcia, E., Murray, M., Strobele, H., White, S., The RHIC zero-degree calorimeters (2003) Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 499 (2-3), pp. 433-436. , DOI 10.1016/j.nima.2003.08.112Llope, W., (2012) Nucl. Instrum. Methods Phys. Res., Sect. A, 661, pp. S110. , (Suppl. 1),. NIMAER 0168-9002 10.1016/j.nima.2010.07.086Reed, R., (2010) J. Phys.: Conf. Ser., 219, p. 03020. , 1742-6596 10.1088/1742-6596/219/3/032020Beringer, J., (2012) Phys. Rev. D, 86, p. 010001. , (Particle Data Group),. 10.1103/PhysRevD.86.010001Beddo, M., Bielick, E., Fornek, T., Guarino, V., Hill, D., Krueger, K., LeCompte, T., Suaide, A.A.P., The STAR barrel electromagnetic calorimeter (2003) Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 499 (2-3), pp. 725-739. , DOI 10.1016/S0168-9002(02)01970-8Miller, M.L., Reygers, K., Sanders, S.J., Steinberg, P., (2007) Annu. Rev. Nucl. Part. Sci., 57, p. 205. , ARPSDF 0163-8998 10.1146/annurev.nucl.57.090506.123020Abelev, B.I., (2009) Phys. Lett. B, 673, p. 183. , (STAR Collaboration),. PYLBAJ 0370-2693 10.1016/j.physletb.2009.02.037Bichsel, H., A method to improve tracking and particle identification in TPCs and silicon detectors (2006) Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 562 (1), pp. 154-197. , DOI 10.1016/j.nima.2006.03.009, PII S0168900206005353Shao, M., (2006) Nucl. Instrum. Methods Phys. Res., Sect. A, 558, p. 419. , NIMAER 0168-9002 10.1016/j.nima.2005.11.251Abelev, B.I., (2009) Phys. Rev. C, 79, p. 034909. , (STAR Collaboration),. PRVCAN 0556-2813 10.1103/PhysRevC.79.034909Adamczyk, L., (STAR Collaboration), arXiv:1402.1791Spiridonov, A., arXiv:hep-ex/0510076Abelev, B.I., (2009) Phys. Rev. C, 80, p. 041902. , (STAR Collaboration),. PRVCAN 0556-2813 10.1103/PhysRevC.80.041902Tang, Z., Xu, Y., Ruan, L., Van Buren, G., Wang, F., Xu, Z., (2009) Phys. Rev. C, 79, p. 051901. , PRVCAN 0556-2813 10.1103/PhysRevC.79.051901Tang, Z., Yi, L., Ruan, L., Shao, M., Chen, H., (2013) Chin. Phys. Lett., 30, p. 031201. , CPLEEU 0256-307X 10.1088/0256-307X/30/3/031201Adare, A., (2010) Phys. Rev. D, 82, p. 012001. , (PHENIX Collaboration),. 10.1103/PhysRevD.82.012001Liu, Y., Qu, Z., Xu, N., Zhuang, P., (2009) Phys. Lett. B, 678, p. 72. , PYLBAJ 0370-2693 10.1016/j.physletb.2009.06.006Heinz, U.W., Shen, C., (private communication)Adare, A., (2008) Phys. Rev. Lett., 101, p. 122301. , (PHENIX Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.101.122301Adams, J., (2003) Phys. Rev. Lett, 91, p. 172302. , (STAR Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.91.172302Adare, A., Afanasiev, S., Aidala, C., Ajitanand, N.N., Akiba, Y., Al-Bataineh, H., Alexander, J., Aoki, K., J/ψ Production versus transverse momentum and rapidity in p+p collisions at s=200GeV (2007) Physical Review Letters, 98 (23), p. 232002. , http://oai.aps.org/oai?verb=GetRecord&Identifier=oai:aps.org: PhysRevLett.98.232002&metadataPrefix=oai_apsmeta_2, DOI 10.1103/PhysRevLett.98.232002Zhao, X., Rapp, R., (2008) Phys. Lett. B, 664, p. 253. , PYLBAJ 0370-2693 10.1016/j.physletb.2008.03.06

Beam-energy Dependence Of Charge Separation Along The Magnetic Field In Au+au Collisions At Rhic

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies. © 2014 American Physical Society.1135DOE; National Research Foundation; CNRS/IN2P3; NSF; National Research Foundation; NRF-2012004024; National Research FoundationVafa, C., Witten, E., (1984) Phys. Rev. Lett., 53, p. 535. , PRLTAO 0031-9007 10.1103/PhysRevLett.53.535Lee, D.T., (1973) Phys. Rev. D, 8, p. 1226. , PRVDAQ 0556-2821 10.1103/PhysRevD.8.1226Lee, T.D., Wick, G.C., (1974) Phys. Rev. D, 9, p. 2291. , PRVDAQ 0556-2821 10.1103/PhysRevD.9.2291Kharzeev, D.E., McLerran, L.D., Warringa, H.J., (2008) Nucl. Phys., A803, p. 227. , NUPBBO 0375-9474 10.1016/j.nuclphysa.2008.02.298Kharzeev, D., (2006) Phys. Lett. B, 633, p. 260. , PYLBAJ 0370-2693 10.1016/j.physletb.2005.11.075Kharzeev, D., Zhitnitsky, A., (2007) Nucl. Phys., A797, p. 67. , NUPBBO 0375-9474 10.1016/j.nuclphysa.2007.10.001Fukushima, K., Kharzeev, D.E., Warringa, H.J., (2008) Phys. Rev. D, 78, p. 074033. , PRVDAQ 1550-7998 10.1103/PhysRevD.78.074033Kharzeev, E.D., (2010) Ann. Phys. (Amsterdam), 325, p. 205. , APNYA6 0003-4916 10.1016/j.aop.2009.11.002Gatto, R., Ruggieri, M., (2012) Phys. Rev. D, 85, p. 054013. , PRVDAQ 1550-7998 10.1103/PhysRevD.85.054013Abelev, B.I., (2009) Phys. Rev. Lett., 103, p. 251601. , (STAR Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.103.251601Abelev, B.I., (2010) Phys. Rev. C, 81, p. 054908. , (STAR Collaboration),. PRVCAN 0556-2813 10.1103/PhysRevC.81.054908Adamczyk, L., (2013) Phys. Rev. C, 88, p. 064911. , (STAR Collaboration),. PRVCAN 0556-2813 10.1103/PhysRevC.88.064911Adamczyk, L., (2014) Phys. Rev. C, 89, p. 044908. , (STAR Collaboration),. PRVCAN 0556-2813 10.1103/PhysRevC.89.044908Ajitanand, N.N., Esumi, S., Lacey, R.A., Proceedings of the RBRC Workshops, 2010, 96. , http://www.bnl.gov/isd/documents/74466.pdf, (PHENIX Collaboration), in, Vol.Ajitanand, N.N., Lacey, R.A., Taranenko, A., Alexander, J.M., (2011) Phys. Rev. C, 83, p. 011901. , PRVCAN 0556-2813 10.1103/PhysRevC.83.011901Abelev, B.I., (2013) Phys. Rev. Lett., 110, p. 012301. , (ALICE Collaboration),. PRLTAO 0031-9007 10.1103/PhysRevLett.110.012301Bzdak, A., Koch, V., Liao, J., (2010) Phys. Rev. C, 81, p. 031901. , PRVCAN 0556-2813 10.1103/PhysRevC.81.031901Liao, J., Koch, V., Bzdak, A., (2010) Phys. Rev. C, 82, p. 054902. , PRVCAN 0556-2813 10.1103/PhysRevC.82.054902Kharzeev, D.E., Son, D.T., (2011) Phys. Rev. Lett., 106, p. 062301. , PRLTAO 0031-9007 10.1103/PhysRevLett.106.062301Voloshin, A.S., (2004) Phys. Rev. C, 70, p. 057901. , PRVCAN 0556-2813 10.1103/PhysRevC.70.057901Anderson, M., (2003) Nucl. Instrum. Methods Phys. Res., Sect. A, 499, p. 659. , NIMAER 0168-9002 10.1016/S0168-9002(02)01964-2Adams, J., (2005) Phys. Rev. C, 72, p. 014904. , (STAR Collaboration), ()PRVCAN 0556-2813 10.1103/PhysRevC.72.014904Agakishiev, G., (2012) Phys. Rev. C, 86, p. 014904. , (STAR Collaboration), ()PRVCAN 0556-2813 10.1103/PhysRevC.86.014904Adamczyk, L., (2012) Phys. Rev. C, 86, p. 054908. , (STAR Collaboration),. PRVCAN 0556-2813 10.1103/PhysRevC.86.054908Poskanzer, A.M., Voloshin, S.A., (1998) Phys. Rev. C, 58, p. 1671. , PRVCAN 0556-2813 10.1103/PhysRevC.58.1671Barrette, J., (1997) Phys. Rev. C, 56, p. 3254. , PRVCAN 0556-2813 10.1103/PhysRevC.56.3254Ollitrault, J.-Y., Poskanzer, A.M., Voloshin, S.A., (2009) Phys. Rev. C, 80, p. 014904. , PRVCAN 0556-2813 10.1103/PhysRevC.80.014904Abelev, B.I., (2008) Phys. Rev. Lett., 101, p. 252301. , (STAR Collaboration), () and references therein. PRLTAO 0031-9007 10.1103/PhysRevLett.101.252301Bzdak, A., Koch, V., Liao, J., (2011) Phys. Rev. C, 83, p. 014905. , PRVCAN 0556-2813 10.1103/PhysRevC.83.014905Ray, R.L., Longacre, R.S., arXiv:nucl-ex/0008009;Ray, R.L., Longacre, R.S., (private communication)Bass, S.A., (1998) Prog. Part. Nucl. Phys., 41, p. 255. , PPNPDB 0146-6410 10.1016/S0146-6410(98)00058-1Bleicher, M., (1999) J. Phys. G, 25, p. 1859. , JPGPED 0954-3899 10.1088/0954-3899/25/9/308Ma, G.-L., Zhang, B., (2011) Phys. Lett. B, 700, p. 39. , PYLBAJ 0370-2693 10.1016/j.physletb.2011.04.057Okorokov, A.V., (2013) Int. J. Mod. Phys. e, 22, p. 1350041. , IMPEER 0218-3013 10.1142/S0218301313500419Bzdak, A., Koch, V., Liao, J., (2013) Lect. Notes Phys., 871, p. 503. , LNPHA4 0075-8450 10.1007/978-3-642-37305-

Fluctuations Of Charge Separation Perpendicular To The Event Plane And Local Parity Violation In S Nn = 200 Gev Au + Au Collisions At The Bnl Relativistic Heavy Ion Collider

Previous experimental results based on data (∼15×106 events) collected by the STAR detector at the BNL Relativistic Heavy Ion Collider suggest event-by-event charge-separation fluctuations perpendicular to the event plane in noncentral heavy-ion collisions. Here we present the correlator previously used split into its two component parts to reveal correlations parallel and perpendicular to the event plane. The results are from a high-statistics 200-GeV Au + Au collisions data set (57×106 events) collected by the STAR experiment. We explicitly count units of charge separation from which we find clear evidence for more charge-separation fluctuations perpendicular than parallel to the event plane. We also employ a modified correlator to study the possible P-even background in same- and opposite-charge correlations, and find that the P-even background may largely be explained by momentum conservation and collective motion. © 2013 American Physical Society.886NRF-2012004024; National Research FoundationLee, T.D., Yang, C.N., (1956) Phys. Rev., 104. , 1, 254. 0031-899X PHRVAO 10.1103/PhysRev.104.254Vafa, C., Witten, E., (1984) Phys. Rev. Lett., 53. , 2, 535. 0031-9007 PRLTAO 10.1103/PhysRevLett.53.535Lee, T.D., (1973) Phys. Rev. D, 8. , 3, 1226. 0556-2821 10.1103/PhysRevD.8.1226Lee, T.D., Wick, G.C., (1974) Phys. Rev. D, 9. , 4, 2291. 0556-2821 10.1103/PhysRevD.9.2291Kharzeev, D., Parity violation in hot QCD: Why it can happen, and how to look for it (2006) Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 633 (2-3), pp. 260-264. , DOI 10.1016/j.physletb.2005.11.075, PII S0370269305017430Kharzeev, D., Zhitnitsky, A., (2007) Nucl. Phys. A, 797. , 6, 67. 0375-9474 NUPABL 10.1016/j.nuclphysa.2007.10.001Kharzeev, D., McLerran, L.D., Warringa, H.J., (2008) Nucl. Phys. A, 803. , 7, 227. 0375-9474 NUPABL 10.1016/j.nuclphysa.2008.02.298Fukushima, K., Kharzeev, D.E., Warringa, H.J., (2008) Phys. Rev. D, 78. , 8, 074033. 1550-7998 PRVDAQ 10.1103/PhysRevD.78.074033Abelev, B.I., (2009) Phys. Rev. Lett., 103. , 9 (STAR Collaboration), 251601. 0031-9007 PRLTAO 10.1103/PhysRevLett.103. 251601Abelev, B.I., (2010) Phys. Rev. C, 81. , 10 (STAR Collaboration), 054908. 0556-2813 PRVCAN 10.1103/PhysRevC.81. 054908Abelev, B.I., (2013) Phys. Rev. Lett., 110. , 11 (ALICE Collaboration), 012301. 0031-9007 PRLTAO 10.1103/PhysRevLett. 110.012301Ackermann, K.H., Adams, N., Adler, C., Ahammed, Z., Ahmad, S., Allgower, C., Amonett, J., Harris, J.W., STAR detector overview (2003) Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 499 (2-3), pp. 624-632. , DOI 10.1016/S0168-9002(02)01960-5Adams, J., Aggarwal, M.M., Ahammed, Z., Amonett, J., Anderson, B.D., Arkhipkin, D., Averichev, G.S., Bai, Y., Directed flow in Au+Au collisions at sNN=62.4 GeV (2006) Physical Review C - Nuclear Physics, 73 (3), pp. 1-7. , http://oai.aps.org/oai?verb=GetRecord&Identifier=oai:aps.org: PhysRevC.73.034903&metadataPrefix=oai_apsmeta_2, DOI 10.1103/PhysRevC.73.034903, 034903Adamczyk, L., (2012) Phys. Rev. Lett., 108. , 14 (STAR Collaboration), 202301. 0031-9007 PRLTAO 10.1103/PhysRevLett. 108.202301Voloshin, S.A., Parity violation in hot QCD: How to detect it (2004) Physical Review C - Nuclear Physics, 70 (5), pp. 0579011-0579012. , DOI 10.1103/PhysRevC.70.057901, 057901Poskanzer, A.M., Voloshin, S.A., Methods for analyzing anisotropic flow in relativistic nuclear collisions (1998) Physical Review C - Nuclear Physics, 58 (3), pp. 1671-1678. , DOI 10.1103/PhysRevC.58.1671Ollitrault, J.-Y., Poskanzer, A.M., Voloshin, S.A., (2009) Phys. Rev. C, 80. , 17, 014904. 0556-2813 PRVCAN 10.1103/PhysRevC.80.014904Pratt, S., Schlichting, S., Gavin, S., (2011) Phys. Rev. C, 84. , 18, 024909. 0556-2813 PRVCAN 10.1103/PhysRevC.84.024909Schlichting, S., Pratt, S., (2011) Phys. Rev. C, 83. , 19, 014913. 0556-2813 PRVCAN 10.1103/PhysRevC.83.014913Selyuzhenkov, I., Voloshin, S., (2008) Phys. Rev. C, 77. , 20, 034904. 0556-2813 PRVCAN 10.1103/PhysRevC.77.034904Kisiel, A., (2006) Comput. Phys. Commun., 174. , 21, 669. 0010-4655 CPHCBZ 10.1016/j.cpc.2005.11.010Bzdak, A., Koch, V., Liao, J., (2011) Phys. Rev. C, 83. , 22, 014905. 0556-2813 PRVCAN 10.1103/PhysRevC.83.014905Adams, J., Aggarwal, M.M., Ahammed, Z., Amonett, J., Anderson, B.D., Arkhipkin, D., Averichev, G.S., Grebenyuk, O., Azimuthal anisotropy in Au+Au collisions at sNN=200GeV (2005) Physical Review C - Nuclear Physics, 72 (1), pp. 1-23. , http://oai.aps.org/oai/?verb=ListRecords&metadataPrefix= oai_apsmeta_2&set=journal:PRC:72, DOI 10.1103/PhysRevC.72.014904, 014904Ray, R.L., Longacre, R.S., 24, arXiv:nucl-ex/0008009 and private communicationKopylov, G.I., Podgoretsky, M.I., Kopylov, G.I., Podgoretsky, M.I., (1972) Sov. J. Nucl. Phys., 15. , 25a, 219 ()25b, Phys. Lett. B. 50, 472 (1974) 0370-2693 PYLBAJ 10.1016/0370-2693(74)90263-925c, Sov. J. Part. Nucl. 20, 266 (1989)Goldhaber, G., Goldhaber, S., Lee, W., Pais, A., (1960) Phys. Rev., 120. , 26, 325. 0031-899X PHRVAO 10.1103/PhysRev.120.32