Exclusive electroproduction of J/ψ mesons at-HERA

  • S. Chekanov
  • , M. Derrick
  • , J. H. Loizides
  • , S. Magill
  • , S. Miglioranzi
  • , B. Musgrave
  • , J. Repond
  • , R. Yoshida
  • , M. C.K. Mattingly
  • , N. Pavel
  • , P. Antonioli
  • , G. Bari
  • , M. Basile
  • , L. Bellagamba
  • , D. Boscherini
  • , A. Bruni
  • , G. Bruni
  • , G. Cara Romeo
  • , L. Cifarelli
  • , F. Cindolo
  • A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, A. Montanari, R. Nania, F. Palmonari, A. Pesci, L. Rinaldi, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan, D. Bartsch, I. Brock, S. Goers, H. Hartmann, E. Hilger, P. Irrgang, H. P. Jakob, O. Kind, U. Meyer, E. Paul, J. Rautenberg, R. Renner, A. Stifutkin, J. Tandler, K. C. Voss, M. Wang, D. S. Bailey, N. H. Brook, J. E. Cole, G. P. Heath, T. Namsoo, S. Robins, M. Wing, M. Capua, A. Mastroberardino, M. Schioppa, G. Susinno, J. Y. Kim, I. T. Lim, K. J. Ma, M. Y. Pac, M. Helbich, Y. Ning, Z. Ren, W. B. Schmidke, F. Sciulli, J. Chwastowski, A. Eskreys, J. Figiel, A. Galas, K. Olkiewicz, P. Stopa, L. Zawiejski, L. Adamczyk, T. Bołd, I. Grabowska-Bołd, D. Kisielewska, A. M. Kowal, M. Kowal, J. Łukasik, M. Przybycieńn, L. Suszycki, D. Szuba, J. Szuba, A. Kotański, W. Słomiński, V. Adler, U. Behrens, I. Bloch, K. Borras, V. Chiochia, D. Dannheim, G. Drews, J. Fourletova, U. Fricke

Risultato della ricerca: Contributo su rivistaArticolo in rivistapeer review

Abstract

The exclusive electroproduction of J/ψ mesons, ep→epJ/ψ, has been studied with the ZEUS detector at HERA for virtualities of the exchanged photon in the ranges 0.15<Q2<0.8 GeV2 and 2<Q2<100 GeV2 using integrated luminosities of 69 and 83 pb-1, respectively. The photon-proton centre-of-mass energy was in the range 30<W<220 GeV and the squared four-momentum transfer at the proton vertex t <1 GeV2. The cross sections and decay angular distributions are presented as functions of Q2, W and t. The effective parameters of the pomeron trajectory are in agreement with those found in J/ψ photoproduction. The spin-density matrix elements, calculated from the decay angular distributions, are consistent with the hypothesis of s-channel helicity conservation. The ratio of the longitudinal to transverse cross sections, σLT, grows with Q2, whilst no dependence on W or t is observed. The results are in agreement with perturbative QCD calculations and exhibit a strong sensitivity to the gluon distribution in the proton.

Lingua originaleInglese
pagine (da-a)3-37
Numero di pagine35
RivistaNuclear Physics B
Volume695
Numero di pubblicazione1-2
DOI
Stato di pubblicazionePubblicato - 6 set 2004
Pubblicato esternamente

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