Orateur
Description
Hard exclusive meson production is one of the common approaches to constrain Generalised Parton Distributions. Such exclusive measurement and notably exclusive $\pi^{0}$ production were conducted at COMPASS in 2016 and 2017 at the M2 beamline from the CERN SPS using the 160 GeV/$c$ muon beam scattering off a 2.5~m long liquid hydrogen target inserted into a~barrel-shaped time-of-flight detector to record the recoiling target proton. The outgoing photons from the exclusive $\pi^0$ decay were detected by a calorimetry system consisting of large-angle and small-angle calorimeters, and the scattered muon was recorded by the COMPASS spectrometer equipped with about 350~tracking planes.
Exclusive $\pi^{0}$ production is a concurrent process of deeply virtual Compton scattering and provides complementary information for the parametrisation of generalised parton distributions, as well as for their flavour dependency. We will report on the preliminary results on exclusive $\pi^0$ production cross-section from 2016 data dependent on the squared four-momentum transfer $|t|$ and on the azimuthal angle $\phi$ between the scattering plane and the $\pi^0$ production plane. The results will provide a further input to phenomenological models for constraining generalised parton distributions, in particular chiral-odd ("transversity") ones.
