# Measurement of D* Production in Diffractive Deep Inelastic Scattering at HERA

## TL;DR

This paper reports measurements of D* meson production in diffractive deep inelastic scattering at HERA, comparing results with QCD predictions and analyzing the ratio of diffractive to inclusive D* production.

## Contribution

It provides the first detailed measurement of D* production in diffractive DIS and tests QCD predictions using diffractive parton densities.

## Key findings

- Measured cross sections agree with NLO QCD predictions.
- Determined the diffractive to inclusive D* production ratio.
- Validated the use of collinear factorisation in diffractive charm production.

## Abstract

Measurements of $D^{*}(2010)$ meson production in diffractive deep inelastic scattering $(5<Q^{2}<100~{\rm GeV}^{2})$ are presented which are based on HERA data recorded at a centre-of-mass energy $\sqrt{s} = 319{\rm~GeV}$ with an integrated luminosity of $287$ pb$^{-1}$. The reaction $ep \rightarrow eXY$ is studied, where the system $X$, containing at least one $D^{*}(2010)$ meson, is separated from a leading low-mass proton dissociative system $Y$ by a large rapidity gap. The kinematics of $D^{*}$ candidates are reconstructed in the $D^{*}\rightarrow K \pi\pi$ decay channel. The measured cross sections compare favourably with next-to-leading order QCD predictions, where charm quarks are produced via boson-gluon fusion. The charm quarks are then independently fragmented to the $D^{*}$ mesons. The calculations rely on the collinear factorisation theorem and are based on diffractive parton densities previously obtained by H1 from fits to inclusive diffractive cross sections. The data are further used to determine the diffractive to inclusive $D^{*}$ production ratio in deep inelastic scattering.