Recent COMPASS results on Transverse Spin Asymmetries in SIDIS

TL;DR

This paper reviews recent COMPASS measurements of transverse spin asymmetries in SIDIS, focusing on weighted Sivers asymmetries and transversity-induced Lambda polarization, providing new high-statistics results and comparisons with unweighted asymmetries.

Contribution

The paper presents novel high-statistics measurements of weighted Sivers asymmetries and transversity-induced Lambda polarization in SIDIS using COMPASS data, enhancing understanding of transverse spin effects.

Findings

Weighted Sivers asymmetries evaluated in x- and z-bins

Comparison between weighted and unweighted asymmetries

Measurement of transversity-induced Lambda polarization

Abstract

After reviewing the most important COMPASS results on transverse spin effects in SIDIS, I will present the recent work we have done on weighted Sivers asymmetries and "transversity induced" $\Lambda$ polarisation. Using the high statistics data collected in 2010 on a transversely polarised proton target COMPASS has evaluated the transverse momentum weighted Sivers asymmetries both in $x$- and in $z$-bins. The results are also compared with the standard unweighted asymmetries. Using the whole data sample collected over the years on transversely polarised deuteron and proton targets COMPASS has measured the transversity induced $\Lambda$ polarisation in the reaction $\mu N \rightarrow \mu' \Lambda X$. Possible future SIDIS COMPASS measurements will also be briefly mentioned.