arXiv subjects

Benjamin Guiot

Publications and source records attributed to Benjamin Guiot.

8 recordsLinked to original sources

arXiv2026

Production of quarkonium pairs via the fragmentation mechanism

In this manuscript, we analyze the contribution of fragmentation mechanisms to the inclusive hadroproduction of heavy quarkonium pairs, taking into account both single- and double-hadron (dihadron) fragmentation channels. To estimate the contribution of the latter mechanism, we construct a microscopic perturbative model of the dihadron fragmentation function, which is valid in the limit of large invariant masses of the heavy quarkonium pair. Using the Color Glass Condensate framework to evaluate the $Q\bar{Q}$ production amplitude, we find that in LHC kinematics, the single fragmentation of heavy quarks into quarkonium is only a minor correction, whereas dihadron fragmentation can provide a sizable contribution, on par with the contributions of single- and double-parton scattering.

hep-ph↗

arXiv2026

The origin of Bjorken-$x$ dependence in DIS: a case for a $z$-dependent correlator in the CGC

We discuss an inconsistency of the eikonal Color Glass Condensate (CGC) description of Deep Inelastic Scattering (DIS). In this framework, the Bjorken-$x$ dependence enters the cross section solely through the rapidity cutoff $\Lambda=x_b$, leading to an all-order cross section independent of $x_b$. To address this issue, we explore a natural modification in which the CGC correlators depend explicitly on the light-cone momentum fraction $z$, with integration limits determined by $x_b$. This modification is consistent with the physical expectation that the observed non-perturbative structure depends on the probe energy. Our analysis implies that the (small-)$x_b$ variation of the cross section is not solely driven by small-$x$ evolution equations. We support this conclusion through an analysis of existing DIS fits and by demonstrating that a similarly good description of the data can be obtained within the modified framework. Finally, we show that the modified formulation is compatible with $k_t$-factorization, unlike the standard one.

hep-ph↗

arXiv2022

On the normalization of unintegrated parton densities

Recently, the definitions of the Kimber-Martin-Ryskin-Watt (KMRW) unintegrated parton densities (UPDFs) have been discussed by several groups. In the first part of this manuscript, we remind the issues encountered with these definitions and discuss the proposed solutions. In our opinion, none of these solutions is fully satisfactory. We observe that these issues seem to be related to the normalization condition where the UPDFs are related to the collinear PDFs by an integration over transverse momentum cut off by the factorization scale. Then, we build a modified version of the angular-ordering KMRW UPDFs, obeying the normalization condition with the transverse momentum integrated up to infinity and show that the usual issues are absent.

hep-ph↗

arXiv2019

Pathologies of the KMR prescriptions for unintegrated PDFs: Which prescription should be preferred?

We discuss the different Kimber-Martin-Ryskin (KMR) prescriptions for unintegrated parton distribution functions (uPDFs). We show that the strong-ordering (SO) and the angular-ordering (AO) cut-offs lead to strong discrepancies between the obtained cross sections. While the result obtained with the AO cut-off overestimates the heavy-flavor cross section by about a factor 3, the SO cut-off gives the correct answer. We also solve the issue of the KMR uPDFs definitions mentioned by Golec-Biernat and Sta\'sto, and show that, in the case of the AO cut-off, the KMR uPDFs are ill-defined.

hep-ph↗

arXiv2019

First results of EPOS-HQ model for open heavy flavor production in A-A collission at RHIC and LHC

The EPOS-HQ model is a framework designed for predicting heavy-flavor observables both in p-p, p-A and A-A collisions. It results from the integration of the MC$@_s$HQ and EPOS3 codes and should supersede predictions made with each of these two. In this contribution, we briefly present the new ingredients of the EPOS-HQ model as well as some preliminary results. From the comparison with experimental data, we derive some direction of improvement for the near future.

hep-ph↗

arXiv2018

Heavy-quark production with $k_t$-factorization: The importance of the sea-quark distribution

We discuss the fact that $k_t$-factorization calculations for heavy-quark production include only the $gg\rightarrow Q\bar{Q}$ contribution. The cases of fixed-flavor-number scheme and variable-flavor-number scheme calculations are analyzed separately. For the latter, we show that, similarly to the collinear factorization, the main contribution is given by the $Qg\rightarrow Qg$ process. In this scheme, calculations including only the $gg$ contribution should show a large discrepancy with the data. We show that, if they do not, it is because they include (effectively) a large $K$ factor.

hep-ph↗

arXiv2018

Hard scale uncertainty in collinear factorization: Perspective from $k_t$-factorization

We analyze two consequences of the relationship between collinear factorization and $k_t$-factorization. First, we show that the $k_t$-factorization gives a fundamental justification for the choice of the hard scale $Q^2$ done in the collinear factorization. Second, we show that in the collinear factorization there is an uncertainty on this choice which will not be reduced by higher orders. This uncertainty is absent within the $k_t$-factorization formalism.

hep-ph↗

arXiv2014

Hard probes and the event generator EPOS

After a short presentation of the event generator EPOS, we discuss the production of heavy quarks and prompt photons which has been recently implemented. Whereas we have satisfying results for the charm, work on photons is still in progress.

hep-ph↗