New vistas in charm production

Antoni Szczurek

doi:10.1051/epjconf/201920602004

Abstract

We discuss some new aspects of charm production trigerred by recent observations of the LHCb collaboration. The LHCb collaboration measured small asymmetries in production of D+D−mesons as well as $ D_s^ + D_s^ - $ mesons. Is this related to initial quark/antiquark asymmetries in the proton ? Here we discuss a scenario in which unfavored fragmentations $ q/\bar {q} \to D $ and $ s/\bar {s} \to D_s $ are responsible for the asymmetries. We fix the strength of such fragmentations – transition probabilities, by adjusting to the size of the LHCb asymmetries. This has consequences for production of D mesons in forward directions (large xF ) as well as at low energies. Large asymmetries are predicted then in these regions. We present here some of our predictions. Consequences for high-energy neutrino production in the atmosphere are discussed and quantified. The production of Λc baryon at the LHC is disussed. Large deviations from the independent-parton fragmentation picture are found.

Highlights

It is usually assumed that the c/c → D fragmentation is responible for production of charmed mesons
Whether the independent parton fragmentation works for Λc baryons was discussed in [14]
In one of our recent papers we demonstrated that the production of high-energy neutrinos is related to very high pp collision energies and rather large xF

Summary

Introduction

It is usually assumed that the c/c → D fragmentation is responible for production of charmed mesons. The leading-order production of charm is by far insufficient to describe experimental distributions of D mesons in rapidity and transverse momentum. The distribution of light quarks is much larger than distribution of corresponding antiquarks All this suggests that a nonzero subleading fragmentation d → D− and d → D+ would produce an asymmetry when added to the dominant. For Ds meson production asymmetry the situation is more subtle as far as subleading fragmentation is considered. Whether the independent parton fragmentation works for Λc baryons was discussed in [14] In such an approach the cross section can be written as: dσ(pp → hX) ≈.

Neutrino production in the atmosphere

LHCb asymmetries

Asymmetries at low collision energies

Charge-to-neutral D meson ratio

Λc production

Conclusions