New target transverse spin dependent azimuthal asymmetries from COMPASS experiment

TL;DR

This paper reports the first measurements of four previously unmeasured twist-three azimuthal asymmetries in semi-inclusive deep inelastic scattering, using the COMPASS experiment with a polarized muon beam and transversely polarized target.

Contribution

It presents the first experimental measurement of four twist-three azimuthal asymmetries in SIDIS, expanding understanding of transverse spin effects in QCD.

Findings

First measurements of four twist-three asymmetries

Data collected from 2002-2004 with polarized muon beam

Results contribute to understanding of spin-dependent phenomena

Abstract

In general, eight target transverse spin-dependent azimuthal modulations are allowed in semi inclusive deep inelastic scattering of polarized leptons on a transversely polarized target. In the QCD parton model four of these asymmetries can be interpreted within the leading order approach. Two of them, namely Collins and Sivers effects were already measured by HERMES and COMPASS experiments. Other two leading twist and remaining four azimuthal asymmetries which can be interpreted as twist-three contributions have been measured for the first time in COMPASS using a 160 GeV/c longitudinally polarized ($P_{beam}\simeq -0.8$) muon beam and a transversely polarized $^6LiD$ target. We present here the preliminary results from the 2002-2004 data.