Production asymmetry of open charm mesons within unfavoured ragmentation scenario

Rafał Maciuła,A Wrońska,W Przygoda,A Magiera

doi:10.1051/epjconf/201919904007

Rafał Maciuła, A Wrońska + Show 2 more

Open Access

https://doi.org/10.1051/epjconf/201919904007

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Abstract

We consider unfavoured light quark/antiquark to D meson fragmentation. We discuss nonperturbative effects for small transverse momenta. The asymmetry for D+ and D- production measured by the LHCb collaboration provides natural constraints on the parton (quark/antiquark) fragmentation functions. We find that already a fraction of $q/\overline q \to D$ fragmentation probability is sufficient to account for the measured asymmetry. Large D-meson production asymmetries are found for large xF which is related to dominance of light quark/antiquark $q/\overline q \to D$ fragmentation over the standard c → D fragmentation. As a consequence, prompt atmospheric neutrino flux at high neutrino energies can be much larger than for the conventional c → D fragmentation. The latter can constitute a sizeable background for the cosmic neutrinos claimed to be observed recently by the IceCube Observatory.

Highlights

It is believed that the D mesons are produced dominantly via c → D fragmentation mechanism which leads to a symmetric production of mesons and anti-mesons
The production asymmetries were interpreted in Ref. [2] as due to meson cloud mechanism and specific structure of the proton Fock components
The string model approach to the problem of heavy meson production and asymmetries in the production of heavy mesons was discussed in extent in Ref. [3]

Summary

Introduction

It is believed that the D mesons are produced dominantly via c → D fragmentation mechanism which leads to a symmetric production of mesons and anti-mesons. We consider a simple alternative phenomenological explanation using so-called unfavored fragmentation functions responsible for light quark/antiquark fragmentation to D mesons. Such unfavoured fragmentation functions are known to be important e.g. for K+/K− production and corresponding asymmetries obtained at SPS [5] and RHIC [6]. Such asymmetries for kaon production were nicely explained in the picture of subleading parton fragmentation at low energies [7]. Possible consequences for prompt atmospheric neutrino production will be discussed

A theoretical basis of the calculations

The LHCb production asymmetry

Cosequences for prompt atmospheric neutrinos