Measurement of the Longitudinal Spin Transfer to Lambda and Anti-Lambda Hyperons in Polarised Muon DIS

TL;DR

This study measures how muons transfer their spin polarization to lambda and anti-lambda hyperons during deep inelastic scattering, revealing different behaviors and providing insights into hyperon spin dynamics.

Contribution

It provides the first detailed measurements of longitudinal spin transfer to lambda and anti-lambda hyperons in muon DIS, highlighting differences in their polarization transfer.

Findings

D^lambda_LL is compatible with zero across x and xF.

D^anti-lambda_LL increases with xF, reaching 0.4-0.5.

Average D^lambda_LL is approximately -0.012; D^anti-lambda_LL is about 0.249.

Abstract

The longitudinal polarisation transfer from muons to lambda and anti-lambda hyperons, D_LL, has been studied in deep inelastic scattering off an unpolarised isoscalar target at the COMPASS experiment at CERN. The spin transfers to lambda and anti-lambda produced in the current fragmentation region exhibit different behaviours as a function of x and xF . The measured x and xF dependences of D^lambda_LL are compatible with zero, while D^anti-lambda_LL tends to increase with xF, reaching values of 0.4 - 0.5. The resulting average values are D^lambda_LL = -0.012 +- 0.047 +- 0.024 and D^anti-lambda_LL = 0.249 +- 0.056 +- 0.049. These results are discussed in the frame of recent model calculations.