Quarkonium inclusive production: negative NLO cross sections, scale fixing and high-energy resummation

by Prof. Jean-Philippe Lansberg (Paris-Saclay U)

Wednesday 11 Oct 2023, 08:30 → 09:30 Asia/Shanghai

B105 (CHEP)

We address the issue of negative total cross sections for inclusive hadroproduction of pseudoscalar quarkonia (eta(Q)) and photoproduction of vector quarkonia (Psi,Upsilon) at increasing energies in NLO collinear-factorisation computations in the MSbar scheme. We discuss two solutions: (i) fixing the factorisation scale to avoid an over-subtraction of the collinear contributions by the Altarelli-Parisi counter terms at large partonic energies, (ii) resumming ln(1/z) contributions through high-energy factorisation with a new matching to collinear factorisation at finite z. In both cases, we discuss the corresponding phenomenology at different energies including a detailed assessment of the theoretical uncertainties.

References:
- J.P. Lansberg, M. Nefedov and M. A. Ozcelik, Curing the high-energy perturbative instability of vector-quarkonium-photoproduction cross sections at order alpha alpha_s^3 with high-energy factorisation[arXiv:2306.02425 [hep-ph]].
- A. Colpani Serri, Y. Feng, C. Flore, J.P. Lansberg, M.A. Ozcelik, H.S. Shao and Y. Yedelkina, Revisiting NLO QCD corrections to total inclusive Jpsi and Upsilon photoproduction cross sections in lepton-proton collisions,  Phys.Lett.B 835 (2022), 137556 [arXiv:2112.05060 [hep-ph]].
- J.P. Lansberg, M. Nefedov and M.A. Ozcelik, Matching next-to-leading-order and high-energy-resummed calculations of heavy-quarkonium-hadroproduction cross sections, JHEP 05 (2022), 08 [arXiv:2112.06789 [hep-ph]].
- J.P. Lansberg and M.A. Ozcelik, Curing the unphysical behaviour of NLO quarkonium production at the LHC and its relevance to constrain the gluon PDF at low scales, Eur. Phys. J. C 81 (2021) no.6, 497 [arXiv:2012.00702 [hep-ph]]. 

Bio:
* CNRS senior researcher in the theory Dept. of IJCLab Orsay, Paris-Saclay U
* Hired by CNRS in 2010 (at IPN Orsay)
* Postdoc at SLAC (US), Heidelberg (Germany), Ecole Polytechnique (France) between 2005 and 2010
* PhD in Liège (Belgium)

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PKU-111023-Jean-Philippe.pdf