# $D \bar D$ asymmetry at low and high energies and possible consequences for prompt atmospheric neutrinos

## TL;DR

This paper investigates how light quark fragmentation affects D meson asymmetries at various energies, revealing significant implications for atmospheric neutrino flux predictions and providing new insights into charm production mechanisms.

## Contribution

It introduces a model for unfavoured light quark fragmentation to D mesons, explaining observed asymmetries and predicting large effects at high rapidity and low energies.

## Key findings

- Large D^+/D^- and D^0/anti-D^0 asymmetries at low energies.
- Enhanced D meson production due to quark fragmentation at low energies.
- Prompt atmospheric neutrino flux could be significantly higher than previously estimated.

## Abstract

We discuss the role of unfavoured light quark/antiquark to $D$ meson fragmentation. The unknown parameters of fragmentation process are adjusted to describe the asymmetry for $D^+$ and $D^-$ production measured by the LHCb. Predictions for similar asymmetry for neutral $D$ mesons are presented. The predicted asymmetry at large rapidity (or $x_F$) are very large which is related to the valence-quark contribution. As a result, prompt atmospheric neutrino flux at high neutrino energies can be much larger than for the conventional $c \to D$ fragmentation. We predict large rapidity-dependent $D^+/D^-$ and $D^0/{\bar D}^0$ asymmetries for low ($\sqrt{s} =$ 20 - 100 GeV) energies. The $q/\bar q \to D$ fragmentation leads to enhanced production of $D$ mesons at low energies. Predictions for fixed target $p+^{4}\!\textrm{He}$ collisions relevant for a fixed target LHCb experiment are discussed.