Constraining the pion distribution amplitude using Drell-Yan reactions on a proton

arXiv (Cornell University)

Abstract

Using a reaction model that incorporates pion bound state effects and continuum results for proton parton distributions and the pion distribution amplitude, $φ_π$, we deliver parameter-free predictions for the $μ^+$ angular distributions in $πN \to μ^+ μ^- X$ reactions on both unpolarised and polarised targets. The analysis indicates that such angular distributions are sensitive to the pointwise form of $φ_π$ and suggests that unpolarised targets are practically more favourable. The precision of extant data is insufficient for use in charting $φ_π$; hence, practical tests of this approach to charting $φ_π$ must await data with improved precision from new-generation experiments. The reaction model yields a nonzero single-spin azimuthal asymmetry, without reference to $T$-odd parton distribution functions (DFs). This may necessitate additional care when attempting to extract such $T$-odd DFs from data.

Authors 6

1. H. Xing

   Nanjing University

   Affiliation as printed

   Institute for Nonperturbative Physics , Nanjing University , Nanjing , Jiangsu 210093 , China

2. Minghui Ding

   Helmholtz-Zentrum Dresden-Rossendorf

   Affiliation as printed

   Helmholtz-Zentrum Dresden-Rossendorf , Bautzner Landstraße 400 , D-01328 Dresden , Germany

3. Zhu-Fang Cui

   Nanjing University

   Affiliation as printed

   Institute for Nonperturbative Physics , Nanjing University , Nanjing , Jiangsu 210093 , China

4. A. V. Pimikov

   Nanjing University

   Affiliation as printed

   Institute for Nonperturbative Physics , Nanjing University , Nanjing , Jiangsu 210093 , China

5. Craig D. Roberts

   Nanjing University

   Affiliation as printed

   Institute for Nonperturbative Physics , Nanjing University , Nanjing , Jiangsu 210093 , China

   School of Physics , Nanjing University , Nanjing , Jiangsu 210093 , China

6. Sebastian M. Schmidt Aachen III. Physikalisches Institut B

   Helmholtz-Zentrum Dresden-Rossendorf · RWTH Aachen University

   Affiliation as printed

   Helmholtz-Zentrum Dresden-Rossendorf , Bautzner Landstraße 400 , D-01328 Dresden , Germany

   RWTH Aachen University , III. Physikalisches Institut B , D-52074 Aachen , Germany