# Heavy-quark production from Glauber-Gribov theory at LHC

###### Abstract

We present predictions for heavy-quark production for proton-lead collisions at LHC energy 5.5 TeV from Glauber-Gribov theory of nuclear shadowing. We have also made predictions for baseline cold-matter (in other words inital-state) nuclear effects in lead-lead collisions at the same energy that has to be taken into account to understand properly final-state effects.

## 1 Introduction

In the Glauber-Gribov theory [1] nuclear shadowing at low- is related to diffractive structure functions of the nucleon, which are studied experimentally at HERA. The space-time picture of the interaction for production of a heavy-quark state on nuclei changes from longitudinally ordered rescatterings at energies below the critical energy, corresponding to of an active parton from a nucleus becoming smaller than , to the coherent interaction of constituents of the projectile with a target nucleus at energies higher thant the critical one [2]. For production of and in the central rapidity region the transition happens at RHIC energies. In this kinematical region the contribution of Glauber-type diagrams is small and it is necessary to calculate diagrams with interactions between pomerons, which, in our approach, are accomodated in the gluon shadowing. A similar model for -suppression in d+Au collisions at RHIC has been considered in Ref. [3].

Calculation of gluon shadowing was performed in our recent paper [4], where Gribov approach for the calculation of nuclear structure functions was used. The gluon diffractive distributions were taken from the most recent experimental parameterizations of HERA data [5]. The Schwimmer model was used to account for higher-order rescatterings.

## 2 Heavy-quark production at the LHC

We present predictions for the rapidity and centrality dependence of the nuclear modification factor in proton-lead (p+Pb) collisions for both and in Fig. 1 (the data on suppression at GeV is taken from [6], where also a definition of the nuclear modification factor can be found). We predict a similar suppression for open charm, , and bottom, , as for the hidden-flavour particles.

The observed scaling at low energies of the parameter (from ) for production, which is broken already at RHIC, will go to a scaling in at higher energies. This will also be the case for and open charm and bottom.

In Fig. 2 we present predictions for cold-nuclear matter effects due to gluon shadowing in lead-lead (Pb+Pb) collisions at LHC energy TeV for the production of and . The suppression is given as a function of rapidity and centrality. .

## References

## References

- [1] V.N. Gribov 1969 Sov. Phys. JETP 29 483
- [2] K. Boreskov, A. Capella, A. Kaidalov and J. Tran Thanh Van 1993 Phys. Rev. D 47 919
- [3] A. Capella and E.G. Ferreiro, hep-ph/0610313
- [4] I.C. Arsene, L. Bravina, A. Kaidalov, K. Tywoniuk and E. Zabrodin, hep-ph/0705.1596
- [5] H1 Collaboration, A. Aktas et al. 2006 Eur. Phys. J. C 48 715; ibid. 48 749
- [6] PHENIX Collaboration, S.S. Adler et al. 2003 Phys. Rev. Lett. 96 012304