Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at $\sqrt{s}=510$ GeV in $\vec{p}+\vec{p}$ Collisions
PHENIX Collaboration, N. J. Abdulameer, U. Acharya, A. Adare, C. Aidala, N. N. Ajitanand, Y. Akiba, R. Akimoto, M. Alfred, N. Apadula, Y. Aramaki, H. Asano, E. … 展开作者
PHENIX Collaboration, N. J. Abdulameer, U. Acharya, A. Adare, C. Aidala, N. N. Ajitanand, Y. Akiba, R. Akimoto, M. Alfred, N. Apadula, Y. Aramaki, H. Asano, E. T. Atomssa, T. C. Awes, B. Azmoun, V. Babintsev, M. Bai, N. S. Bandara, B. Bannier, K. N. Barish, S. Bathe, A. Bazilevsky, M. Beaumier, S. Beckman, R. Belmont, A. Berdnikov, Y. Berdnikov, L. Bichon, D. Black, B. Blankenship, J. S. Bok, V. Borisov, K. Boyle, M. L. Brooks, J. Bryslawskyj, H. Buesching, V. Bumazhnov, S. Campbell, V. Canoa Roman, C. -H. Chen, M. Chiu, C. Y. Chi, I. J. Choi, J. B. Choi, T. Chujo, Z. Citron, M. Connors, R. Corliss, Y. Corrales Morales, M. Csanád, T. Csörgő, A. Datta, M. S. Daugherity, G. David, C. T. Dean, K. DeBlasio, K. Dehmelt, A. Denisov, A. Deshpande, E. J. Desmond, L. Ding, A. Dion, V. Doomra, J. H. Do, A. Drees, K. A. Drees, J. M. Durham, A. Durum, H. En'yo, A. Enokizono, R. Esha, B. Fadem, W. Fan, N. Feege, D. E. Fields, M. Finger,, M. Finger, D. Firak, D. Fitzgerald, S. L. Fokin, J. E. Frantz, A. Franz, A. D. Frawley, P. Gallus, C. Gal, P. Garg, H. Ge, M. Giles, F. Giordano, A. Glenn, Y. Goto, N. Grau, S. V. Greene, M. Grosse Perdekamp, T. Gunji, H. Guragain, Y. Gu, T. Hachiya, J. S. Haggerty, K. I. Hahn, H. Hamagaki, J. Hanks, S. Y. Han, M. Harvey, S. Hasegawa, T. K. Hemmick, X. He, J. C. Hill, A. Hodges, R. S. Hollis, K. Homma, B. Hong, T. Hoshino, J. Huang, Y. Ikeda, K. Imai, Y. Imazu, M. Inaba, A. Iordanova, D. Isenhower, D. Ivanishchev, B. V. Jacak, S. J. Jeon, M. Jezghani, X. Jiang, Z. Ji, B. M. Johnson, E. Joo, K. S. Joo, D. Jouan, D. S. Jumper, J. H. Kang, J. S. Kang, D. Kawall, A. V. Kazantsev, J. A. Key, V. Khachatryan, A. Khanzadeev, A. Khatiwada, K. Kihara, C. Kim, D. H. Kim, D. J. Kim, E. -J. Kim, H. -J. Kim, M. Kim, T. Kim, Y. K. Kim, D. Kincses, A. Kingan, E. Kistenev, J. Klatsky, D. Kleinjan, P. Kline, T. Koblesky, M. Kofarago, J. Koster, D. Kotov, L. Kovacs, B. Kurgyis, K. Kurita, M. Kurosawa, Y. Kwon, J. G. Lajoie, D. Larionova, A. Lebedev, K. B. Lee, S. H. Lee, M. J. Leitch, M. Leitgab, N. A. Lewis, S. H. Lim, M. X. Liu, X. Li, D. A. Loomis, D. Lynch, S. Lökös, T. Majoros, Y. I. Makdisi, M. Makek, A. Manion, V. I. Manko, E. Mannel, M. McCumber, P. L. McGaughey, D. McGlinchey, C. McKinney, A. Meles, M. Mendoza, B. Meredith, Y. Miake, A. C. Mignerey, A. J. Miller, A. Milov, D. K. Mishra, J. T. Mitchell, M. Mitrankova, Iu. Mitrankov, S. Miyasaka, S. Mizuno, M. M. Mondal, P. Montuenga, T. Moon, D. P. Morrison, T. V. Moukhanova, A. Muhammad, B. Mulilo, T. Murakami, J. Murata, A. Mwai, S. Nagamiya, J. L. Nagle, M. I. Nagy, I. Nakagawa, H. Nakagomi, K. Nakano, C. Nattrass, S. Nelson, P. K. Netrakanti, M. Nihashi, T. Niida, R. Nouicer, N. Novitzky, G. Nukazuka, A. S. Nyanin, E. O'Brien, C. A. Ogilvie, J. Oh, J. D. Orjuela Koop, M. Orosz, J. D. Osborn, A. Oskarsson, K. Ozawa, R. Pak, V. Pantuev, V. Papavassiliou, J. S. Park, S. Park, L. Patel, M. Patel, S. F. Pate, J. -C. Peng, W. Peng, D. V. Perepelitsa, G. D. N. Perera, D. Yu. Peressounko, C. E. PerezLara, J. Perry, R. Petti, C. Pinkenburg, R. Pinson, R. P. Pisani, M. Potekhin, A. Pun, M. L. Purschke, P. V. Radzevich, J. Rak, N. Ramasubramanian, I. Ravinovich, K. F. Read, D. Reynolds, V. Riabov, Y. Riabov, D. Richford, N. Riveli, D. Roach, S. D. Rolnick, M. Rosati, Z. Rowan, J. G. Rubin, J. Runchey, N. Saito, T. Sakaguchi, H. Sako, V. Samsonov, M. Sarsour, S. Sato, S. Sawada, B. Schaefer, B. K. Schmoll, K. Sedgwick, J. Seele, R. Seidl, A. Sen, R. Seto, P. Sett, A. Sexton, D. Sharma, I. Shein, M. Shibata, T. -A. Shibata, K. Shigaki, M. Shimomura, Z. Shi, P. Shukla, A. Sickles, C. L. Silva, D. Silvermyr, B. K. Singh, C. P. Singh, V. Singh, M. Slunečka, K. L. Smith, R. A. Soltz, W. E. Sondheim, S. P. Sorensen, I. V. Sourikova, P. W. Stankus, M. Stepanov, S. P. Stoll, T. Sugitate, A. Sukhanov, T. Sumita, J. Sun, Z. Sun, J. Sziklai, R. Takahama, A. Takahara, A. Taketani, K. Tanida, M. J. Tannenbaum, S. Tarafdar, A. Taranenko, A. Timilsina, T. Todoroki, M. Tomášek, H. Torii, M. Towell, R. Towell, R. S. Towell, I. Tserruya, Y. Ueda, B. Ujvari, H. W. van Hecke, M. Vargyas, J. Velkovska, M. Virius, V. Vrba, E. Vznuzdaev, X. R. Wang, Z. Wang, D. Watanabe, Y. Watanabe, Y. S. Watanabe, F. Wei, S. Whitaker, S. Wolin, C. P. Wong, C. L. Woody, M. Wysocki, B. Xia, L. Xue, S. Yalcin, Y. L. Yamaguchi, A. Yanovich, I. Yoon, I. Younus, I. E. Yushmanov, W. A. Zajc, A. Zelenski, L. Zou
备注：
358 authors from 72 institutions, 8 pages, 2 figures, 1 table, 2013 data. v2 is version accepted by Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.html
We present measurements of the cross section and double-helicity asymmetry $A_{LL}$ of direct-photon production in $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=510$ GeV. The measurements have been performed at midrapidity ($|η|<0.25$) with the PHENIX detector at the Relativistic Heavy Ion Collider. At relativistic energies, direct photons are dominantly produced from the initial quark-gluon hard scattering and do not interact via the strong force at leading order. Therefore, at $\sqrt{s}=510$ GeV, where leading-order-effects dominate, these measurements provide clean and direct access to the gluon helicity in the polarized proton in the gluon-momentum-fraction range $0.02<x<0.08$, with direct sensitivity to the sign of the gluon contribution.
Transverse momentum dependence of the quark helicity distributions and the Cahn effect in double-spin asymmetry $A_{LL}$ in Semi Inclusive DIS
在半包含深度非弹性散射的LO QCD部分子模型$\ell N \to \ell h X$中，利用未积分的夸克分布和碎裂函数，研究了双夸克自旋不对称性$A_{LL}$对$\bfP_{hT}$的依赖性.我们包括1/Q的运动学修正，诱导方位调制的不对称性，类似于在非极化SIDIS的卡恩效应。我们表明，$A_{LL}$和加权DSA $A_{LL}^{\cosϕ_h}$的研究允许提取的横向动量依赖的未积分螺旋度分布函数$g_{1L}^q(x,k_\perp)$ [或$Δq(x, k_\perp)]$。预测，基于一些模型的未知功能，给出了正在进行的COMPASS，HERMES和JLab实验。
Measurement of the parity-violating asymmetry parameter alpha_b and the helicity amplitudes for the decay Lambda_b->J/psi+Lambda with the ATLAS detector
The gluon spin contribution to the proton spin from the double helicity asymmetry in inclusive pi^0 production in polarized p+p collisions at sqrt(s)=200 GeV
Inclusive cross section and double helicity asymmetry for π^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton
Beam-helicity asymmetry in photon and pion electroproduction in the Delta(1232) resonance region at Q^2= 0.35 (GeV/c)^2
在$Q^2=$ 0.35（GeV/c）$^2$的$Δ(1232)$共振区同时测量了反应（ep \to ep γ）和（ep \to ep π^0）的束流螺旋度不对称性.该实验是在MAMI进行的，使用纵向偏振光束和质子的面外探测。计算结果进行了比较的基础上的色散关系的虚拟康普顿散射和π电生产的MAID模型。实验结果与理论计算结果基本吻合。其余的差异可能归因于某些$γ^{(*)} N \to πN$多极的参数化不完善，主要导致非共振背景。两个通道（$γ$和$π^0$）中的光束螺旋度不对称性对这些多极子显示出良好的灵敏度，并且应该允许将来在其参数化中进行改进。
Longitudinal double spin asymmetry of $π^{\pm}$-tagged jet, $Λ$, $\overlineΛ$, and $K_S^0$ in polarized $p+p$ collisions at $\sqrt{s}=200$ $\rm{GeV}$ at STAR
