A measurement of the ratio R_chi_c=(chi_c-->J/psi+gamma)/J/psi in pC , pTi , and pW interactions at 920 GeV/c ( sqrt(s)=41.6 Gev ) in the Feynman-x range -0.35<x^J/psi_F<0.15 is presented . Both mu^+ mu^- and e^+ e^- J/psi decay channels are observed with an overall statistics of about 15000 chi_c events , which is by far the largest available sample in pA collisions . The result is R_chi_c=0.188+/-0.013^+0.024_st-0.022sys averaged over the different materials , when no J/psi and chi_c polarizations are considered . The chi_c1 to chi_c2 production ratio R_12=R_chi_c1/R_chi_c2 is measured to be 1.02+/- 0.40 , leading to a cross section ratio sigma(chi_c1)/sigma(chi_c2)=0.57+/-0.23 . The dependence of R_chi_c on the Feynman-x of the J/psi , x^J/psi_F , and its transverse momentum , p^J/psi_T , is studied , as well as its dependence on the atomic number , A , of the target . For the first time , an extensive study of possible biases on R_chi_c and R_12 due to the dependence of acceptance on the polarization states of J/psi and chi_c is performed . By varying the polarization parameter , lambda_obs , of all produced J/psi's by two sigma around the value measured by HERA-B , and considering the maximum variation due to the possible chi_c1 and chi_c2 polarizations , it is shown that R_chi_c could change by a factor between 1.02 and R_12 by a factor between 0.89 and 1.16 .

Production of the charmonium states chi_c1 and chi_c2 in proton nucleus interactions at sqrt(s)=41.6 GeV

BERTIN, ANTONIO;DE CASTRO, STEFANO;FABBRI, LAURA;MASSA, IGNAZIO GIACOMO;PICCININI, MAURIZIO;SBRIZZI, ANTONIO;SEMPRINI CESARI, NICOLA;VILLA, MAURO;VITALE, ANTONIO;ZOCCOLI, ANTONIO
2009

Abstract

A measurement of the ratio R_chi_c=(chi_c-->J/psi+gamma)/J/psi in pC , pTi , and pW interactions at 920 GeV/c ( sqrt(s)=41.6 Gev ) in the Feynman-x range -0.35<x^J/psi_F<0.15 is presented . Both mu^+ mu^- and e^+ e^- J/psi decay channels are observed with an overall statistics of about 15000 chi_c events , which is by far the largest available sample in pA collisions . The result is R_chi_c=0.188+/-0.013^+0.024_st-0.022sys averaged over the different materials , when no J/psi and chi_c polarizations are considered . The chi_c1 to chi_c2 production ratio R_12=R_chi_c1/R_chi_c2 is measured to be 1.02+/- 0.40 , leading to a cross section ratio sigma(chi_c1)/sigma(chi_c2)=0.57+/-0.23 . The dependence of R_chi_c on the Feynman-x of the J/psi , x^J/psi_F , and its transverse momentum , p^J/psi_T , is studied , as well as its dependence on the atomic number , A , of the target . For the first time , an extensive study of possible biases on R_chi_c and R_12 due to the dependence of acceptance on the polarization states of J/psi and chi_c is performed . By varying the polarization parameter , lambda_obs , of all produced J/psi's by two sigma around the value measured by HERA-B , and considering the maximum variation due to the possible chi_c1 and chi_c2 polarizations , it is shown that R_chi_c could change by a factor between 1.02 and R_12 by a factor between 0.89 and 1.16 .
I. ABT ; M. ADAMS ; M. AGARI ; H. ALBRECHT ; A. ALEXANDROV ; V. AMARAL ; A. AMORIM ; S. J. APLIN ; V. AUSHEV ; Y. BAGATURIA ; V. BALAGURA ; M. BARGIOTTI ; O. BARSUKOVA ; J. BASTOS ; J. BATISTA ; C. BAUER ; T. S. BAUER ; A. BELKOV ; AR. BELKOV ; I. BELOTELOV ; A. BERTIN ; B. BOBCHENKO ; M. BOECKER ; A. BOGATYREV ; G. BOHM ; M. BRAUER ; M. BRUINSMA ; M. BRUSCHI ; P. BUCHHOLZ ; T. BURAN ; J. CARVALHO ; P. CONDE ; C. CRUSE ; M. DAM ; K. M. DANIELSEN ; M. DANILOV ; S. DE CASTRO ; H. DEPPE ; X. DONG ; H. B. DREIS ; V. EGORYTCHEV ; K. EHRET ; F. EISELE ; D. EMELIYANOV ; S. ESSENOV ; L. FABBRI ; P. FACCIOLI ; M. FEUERSTACK-RAIBLE ; J. FLAMMER ; B. FOMINYKH ; M. FUNCKE ; L. GARRIDO ; A. GELLRICH ; B. GIACOBBE ; J. GLAESS ; D. GOLOUBKOV ; Y. GOLUBKOV ; A. GOLUTVIN ; I. GOLUTVIN ; I. GORBOUNOV ; A. GORISEK ; O. GOUCHTCHINE ; D. C. GOULART ; S. GRADL ; W. GRADL ; F. GRIMALDI ; J. GROTH-JENSEN ; YU. GUILITSKY ; J. D. HANSEN ; J. M. HERNANDEZ ; W. HOFMANN ; M. HOHLMANN ; T. HOTT ; W. HULSBERGEN ; U. HUSEMANN ; O. IGONKINA ; M. ISPIRYAN ; T. JAGLA ; C. JIANG ; H. KAPITZA ; S. KARABEKYAN ; N. KARPENKO ; S. KELLER ; J. KESSLER ; F. KHASANOV ; YU. KIRYUSHIN ; I. KISEL ; E. KLINKBY ; K. T. KNOEPFLE ; H. KOLANOSKI ; S. KORPAR ; C. KRAUSS ; P. KREUZER ; P. KRIZAN ; D. KRUECKER ; S. KUPPER ; T. KVARATSSKHELIIA ; A. LANYOV ; K. LAU ; B. LEWENDEL ; T. LOHSE ; B. LOMONOSOV ; R. MAENNER ; R. MANKEL ; S. MASCIOCCHI ; I. MASSA ; I. MATCHIKHILIAN ; G. MEDIN ; M. MEDINNIS ; M. MEVIUS ; A. MICHETTI ; YU. MIKHAILOV ; R. MIZUK ; R.MURESAN ; M. ZUR NEDDEN ; M. NEGODAEV ; M. NOERENBERG ; S. NOWAK ; M. T. NUNEZ PARDO DE VERA ; M. OUCHRIF ; F. OULD-SAADA ; C. PADILLA ; D. PERALTA ; R. PERNACK ; R. PESTOTNIK ; B. A. PETERSEN ; M. PICCININI ; M. A. PLEIER ; M. POLI ; V. POPOV ; D. POSE ; S. PRYSTUPA ; V. PUGATCH ; Y. PYLYPCHENKO ; J. PYRLIK ; K. REEVES ; D. RESSING ; H. RICK ; I. RIU ; P. ROBMANN ; I. ROSTOVTSEVA ; V. RYBNIKOV ; F. SANCHEZ ; A. SBRIZZI ; M. SCHMELLING ; B. SCHMIDT ; A. SCHREINER ; H. SCHROEDER ; U. SCHWANKE ; A. J. SCHWARTZ ; A. S. SCHWARZ ; B. SCHWENNINGER ; B. SCHWINGENHEUER ; F. SCIACCA ; N. SEMPRINI-CESARI ; S. SHUVALOV ; L. SILVA ; L. SOZUER ; S. SOLUNIN ; A. SOMOV ; S. SOMOV ; J. SPENGLER ; R. SPIGHI ; A. SPIRIDONOV ; A. STANOVNIK ; M. STARIC ; C. STEGMANN ; H. S. SUBRAMANIA ; M. SYMALLA ; I. TIKHOMIROV ; M. TITOV ; I. TSAKOV ; U. UWER ; C. VAN ELDIK ; YU. VASSILIEV ; M. VILLA ; A. VITALE ; I. VUKOTIC ; H. WAHLBERG ; A. H. WALENTA ; M. WALTER ; J. J. WANG ; D. WEGENER ; U. WERTHENBACH ; H. WOLTERS ; R. WURTH ; A. WURZ ; S. XELLA-HANSEN ; YU. ZAITSEV ; M. ZAVERTYAEV ; T. ZEUNER ; A. ZHELEZOV ; Z. ZHENG ; R. ZIMMERMANN ; T. ZIVKO; A. ZOCCOLI
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/72989
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