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Longitudinal and transverse spin asymmetries for inclusive jet production at mid-rapidity in polarized p+p collisions at sqrt{s}=200 GeV

The STAR Collaboration, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, C. D. Anson, D. Arkhipkin, E. Aschenauer, G. S. Averichev, J. Balewski, A. Banerjee, Z. Barnovska, D. R. Beavis, R. Bellwied, M. J. Betancourt, R. R. Betts, A. Bhasin, A. K. Bhati, H. Bichsel, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, W. Borowski, J. Bouchet, A. V. Brandin, A. Bridgeman, S. G. Brovko, E. Bruna, S. Bueltmann, I. Bunzarov, T. P. Burton, J. Butterworth, X. Z. Cai, H. Caines, M. Calderón de la Barca Sánchez, D. Cebra, R. Cendejas, M. C. Cervantes, P. Chaloupka, S. Chattopadhyay, H. F. Chen, J. H. Chen, J. Y. Chen, L. Chen, J. Cheng, M. Cherney, A. Chikanian, W. Christie, P. Chung, J. Chwastowski, M. J. M. Codrington, R. Corliss, J. G. Cramer, H. J. Crawford, X. Cui, A. Davila Leyva, L. C. De Silva, R. R. Debbe, T. G. Dedovich, J. Deng, R. Derradi de Souza, S. Dhamija, L. Didenko, F. Ding, A. Dion, P. Djawotho, X. Dong, J. L. Drachenberg, J. E. Draper, C. M. Du, L. E. Dunkelberger, J. C. Dunlop, L. G. Efimov, M. Elnimr, J. Engelage, G. Eppley, L. Eun, O. Evdokimov, R. Fatemi, S. Fazio, J. Fedorisin, R. G. Fersch, P. Filip, E. Finch, Y. Fisyak, C. A. Gagliardi, D. R. Gangadharan, F. Geurts, S. Gliske, Y. N. Gorbunov, O. G. Grebenyuk, D. Grosnick, S. Gupta, W. Guryn, B. Haag, O. Hajkova, A. Hamed, L-X. Han, J. W. Harris, J. P. Hays-Wehle, S. Heppelmann, A. Hirsch, G. W. Hoffmann, D. J. Hofman, S. Horvat, B. Huang, H. Z. Huang, P. Huck, T. J. Humanic, L. Huo, G. Igo, W. W. Jacobs, C. Jena, J. Joseph, E. G. Judd, S. Kabana, K. Kang, J. Kapitan, K. Kauder, H. W. Ke, D. Keane, A. Kechechyan, A. Kesich, D. Kettler, D. P. Kikola, J. Kiryluk, A. Kisiel, V. Kizka, S. R. Klein, D. D. Koetke, T. Kollegger, J. Konzer, I. Koralt, L. Koroleva, W. Korsch, L. Kotchenda, K. Kowalik, P. Kravtsov, K. Krueger, L. Kumar, M. A. C. Lamont, J. M. Landgraf, S. LaPointe, J. Lauret, A. Lebedev, R. Lednicky, J. H. Lee, W. Leight, M. J. LeVine, C. Li, L. Li, W. Li, X. Li, X. Li, Y. Li, Z. M. Li, L. M. Lima, M. A. Lisa, F. Liu, T. Ljubicic, W. J. Llope, R. S. Longacre, Y. Lu, X. Luo, A. Luszczak, G. L. Ma, Y. G. Ma, D. M. M. D. Madagodagettige Don, D. P. Mahapatra, R. Majka, O. I. Mall, S. Margetis, C. Markert, H. Masui, H. S. Matis, D. McDonald, T. S. McShane, J. Millane, S. Mioduszewski, M. K. Mitrovski, Y. Mohammed, B. Mohanty, M. M. Mondal, B. Morozov, M. G. Munhoz, M. K. Mustafa, M. Naglis, B. K. Nandi, Md. Nasim, T. K. Nayak, L. V. Nogach, J. Novak, G. Odyniec, A. Ogawa, K. Oh, A. Ohlson, V. Okorokov, E. W. Oldag, R. A. N. Oliveira, D. Olson, P. Ostrowski, M. Pachr, B. S. Page, S. K. Pal, Y. X. Pan, Y. Pandit, Y. Panebratsev, T. Pawlak, B. Pawlik, H. Pei, C. Perkins, W. Peryt, P. Pile, M. Planinic, J. Pluta, D. Plyku, N. Poljak, J. Porter, A. M. Poskanzer, C. B. Powell, D. Prindle, C. Pruneau, N. K. Pruthi, M. Przybycien, P. R. Pujahari, J. Putschke, H. Qiu, R. Raniwala, S. Raniwala, R. L. Ray, R. Redwine, R. Reed, C. K. Riley, H. G. Ritter, J. B. Roberts, O. V. Rogachevskiy, J. L. Romero, J. F. Ross, L. Ruan, J. Rusnak, N. R. Sahoo, I. Sakrejda, T. Sakuma, S. Salur, A. Sandacz, J. Sandweiss, E. Sangaline, A. Sarkar, M. Sarsour, J. Schambach, R. P. Scharenberg, A. M. Schmah, B. Schmidke, N. Schmitz, T. R. Schuster, J. Seele, J. Seger, P. Seyboth, N. Shah, E. Shahaliev, M. Shao, B. Sharma, M. Sharma, S. S. Shi, Q. Y. Shou, E. P. Sichtermann, R. N. Singaraju, M. J. Skoby, D. Smirnov, N. Smirnov, D. Solanki, P. Sorensen, U. G. deSouza, H. M. Spinka, B. Srivastava, T. D. S. Stanislaus, D. Staszak, S. G. Steadman, J. R. Stevens, R. Stock, M. Strikhanov, B. Stringfellow, A. A. P. Suaide, M. C. Suarez, M. Sumbera, X. M. Sun, Y. Sun, Z. Sun, B. Surrow, D. N. Svirida, T. J. M. Symons, A. Szanto de Toledo, J. Takahashi, A. H. Tang, Z. Tang, L. H. Tarini, T. Tarnowsky, D. Thein, J. H. Thomas, J. Tian, A. R. Timmins, D. Tlusty, M. Tokarev, T. A. Trainor, S. Trentalange, R. E. Tribble, P. Tribedy, B. A. Trzeciak, O. D. Tsai, J. Turnau, T. Ullrich, D. G. Underwood, G. Van Buren, G. van Nieuwenhuizen, J. A. Vanfossen,, R. Varma, G. M. S. Vasconcelos, F. Videbæk, Y. P. Viyogi, S. Vokal, S. A. Voloshin, A. Vossen, M. Wada, F. Wang, G. Wang, H. Wang, J. S. Wang, Q. Wang, X. L. Wang, Y. Wang, G. Webb, J. C. Webb, G. D. Westfall, C. Whitten, H. Wieman, S. W. Wissink, R. Witt, W. Witzke, Y. F. Wu, Z. Xiao, W. Xie, K. Xin, H. Xu, N. Xu, Q. H. Xu, W. Xu, Y. Xu, Z. Xu, L. Xue, Y. Yang, Y. Yang, P. Yepes, Y. Yi, K. Yip, I-K. Yoo, M. Zawisza, H. Zbroszczyk, J. B. Zhang, S. Zhang, W. M. Zhang, X. P. Zhang, Y. Zhang, Z. P. Zhang, F. Zhao, J. Zhao, C. Zhong, X. Zhu, Y. H. Zhu, Y. Zoulkarneeva

TL;DR

The study uses inclusive mid-rapidity jet production in polarized p+p collisions at sqrt{s}=200 GeV to probe proton spin structure. It reports precise measurements of A_LL, A_N, A_Sigma, and A_TT, with a focus on disentangling gluon polarization and potential Sivers/transversity effects, while carefully controlling backgrounds and systematic uncertainties. The results show no significant transverse spin asymmetries and provide strong constraints on the gluon Sivers and gluon helicity distributions, improving global understanding of Delta G in the accessed x-range and informing future global analyses like DSSV. Overall, the work demonstrates the power of RHIC-STAR jet measurements to constrain spin-dependent parton distributions and guide theoretical models of nucleon spin.

Abstract

We report STAR measurements of the longitudinal double-spin asymmetry A_LL, the transverse single-spin asymmetry A_N, and the transverse double-spin asymmetries A_Sigma and A_TT for inclusive jet production at mid-rapidity in polarized p+p collisions at a center-of-mass energy of sqrt{s} = 200 GeV. The data represent integrated luminosities of 7.6 /pb with longitudinal polarization and 1.8 /pb with transverse polarization, with 50-55% beam polarization, and were recorded in 2005 and 2006. No evidence is found for the existence of statistically significant jet A_N, A_Sigma, or A_TT at mid-rapidity. Recent model calculations indicate the A_N results may provide new limits on the gluon Sivers distribution in the proton. The asymmetry A_LL significantly improves the knowledge of gluon polarization in the nucleon.

Longitudinal and transverse spin asymmetries for inclusive jet production at mid-rapidity in polarized p+p collisions at sqrt{s}=200 GeV

TL;DR

The study uses inclusive mid-rapidity jet production in polarized p+p collisions at sqrt{s}=200 GeV to probe proton spin structure. It reports precise measurements of A_LL, A_N, A_Sigma, and A_TT, with a focus on disentangling gluon polarization and potential Sivers/transversity effects, while carefully controlling backgrounds and systematic uncertainties. The results show no significant transverse spin asymmetries and provide strong constraints on the gluon Sivers and gluon helicity distributions, improving global understanding of Delta G in the accessed x-range and informing future global analyses like DSSV. Overall, the work demonstrates the power of RHIC-STAR jet measurements to constrain spin-dependent parton distributions and guide theoretical models of nucleon spin.

Abstract

We report STAR measurements of the longitudinal double-spin asymmetry A_LL, the transverse single-spin asymmetry A_N, and the transverse double-spin asymmetries A_Sigma and A_TT for inclusive jet production at mid-rapidity in polarized p+p collisions at a center-of-mass energy of sqrt{s} = 200 GeV. The data represent integrated luminosities of 7.6 /pb with longitudinal polarization and 1.8 /pb with transverse polarization, with 50-55% beam polarization, and were recorded in 2005 and 2006. No evidence is found for the existence of statistically significant jet A_N, A_Sigma, or A_TT at mid-rapidity. Recent model calculations indicate the A_N results may provide new limits on the gluon Sivers distribution in the proton. The asymmetry A_LL significantly improves the knowledge of gluon polarization in the nucleon.

Paper Structure

This paper contains 33 sections, 4 equations, 16 figures, 8 tables.

Table of Contents

  1. Introduction
  2. Experiment and Data
  3. RHIC-STAR
  4. Triggers and Data Sets
  5. Jets
  6. Jet-Finding and Reconstruction
  7. Event and Jet Cuts
  8. Background Events
  9. Beam-Gas Events
  10. Electron-like Events
  11. Simulations
  12. Jet Energy Scale
  13. TPC and Calorimeter Calibration
  14. Jet $p_T$ Scale Corrections
  15. Pile-up Corrections
  16. ...and 18 more sections

Figures (16)

  • Figure 1: Schematic section cut of the STAR detector showing the detector elements used in these measurements.
  • Figure 2: Schematic diagram showing the location of the fixed jet patches and calorimeter towers in the STAR Barrel Electromagnetic Calorimeter.
  • Figure 3: (color online) Neutral energy fraction (NEF) distributions for mono- and di-jets for 2006 data (symbols) and Monte Carlo simulation (histograms). These events have uncorrected jet $p_T$ in the range $14.08~<~p_{T}~<~17.31$ GeV/$c$.
  • Figure 4: (color online) Fits of the mono/di-jet ratio vs. NEF for 2006 data. The total fit (red solid curve) includes a decaying exponential for the background (blue dotted curve) and a first order polynomial for the signal (green dashed curve). These events have uncorrected jet $p_T$ in the range $14.08~<~p_{T}~<~17.31$ GeV/$c$.
  • Figure 5: (color online) Relative difference in $p_{T}$ for back-to-back di-jets for 2006 data. Both jets satisfy all cuts, including the trigger-matching requirement. These events have uncorrected jet $p_T$ in the range $14.08~<~(p_{T,1}+p_{T,2})/2~<~17.31$ GeV/$c$. For this case, we find $\sim$ 5% discrepancy between data and Monte Carlo simulations. Essentially all the bins match simulations to within 10$\%$. The $p_{T}$ resolution is estimated to be $\sim$ 23$\%$ from this graph.
  • ...and 11 more figures