Towards a Solution of the Charmonium Production Controversy: <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="italic">k</mi></mrow><mrow><mi>⊥</mi></mrow></msub></mrow></math></span> Factorization versus Color-Octet Mechanism

Ph. Hägler; R. Kirschner; A. Schäfer; L. Szymanowski; O. V. Teryaev

doi:10.1103/PhysRevLett.86.1446

Towards a Solution of the Charmonium Production Controversy: $k_{⊥}$ Factorization versus Color-Octet Mechanism

Ph. Hägler, R. Kirschner, A. Schäfer, L. Szymanowski, and O. V. Teryaev

Phys. Rev. Lett. 86, 1446 – Published 19 February 2001

Abstract

The cross section of $χ_{cJ}$ hadroproduction is calculated in the $k_{⊥}$ -factorization approach. We find a significant contribution of the $χ_{c 1}$ state due to non-applicability of the Landau-Yang theorem because of off-shell gluons. The results are in agreement with data and, in contrast to the collinear factorization, show a dominance of the color-singlet part and a strong suppression of the color octet contribution. Our results could therefore lead to a solution of the long-standing controversy between the color-singlet model and the color-octet mechanism.

Received 30 May 2000

DOI:https://doi.org/10.1103/PhysRevLett.86.1446

Authors & Affiliations

Ph. Hägler¹, R. Kirschner², A. Schäfer¹, L. Szymanowski^1,3, and O. V. Teryaev^4,5

¹Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
²Institut für Theoretische Physik, Universität Leipzig, D-04109 Leipzig, Germany
³Soltan Institute for Nuclear Studies, Hoza 69, 00689 Warsaw, Poland
⁴Centre de Physique Theorique (UMR C7644), Ecole Polytechnique, Palaiseau, France
⁵Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia