# The leptonic current structure and azimuthal asymmetry in deeply inelastic scattering

## TL;DR

This paper derives a compact form of leptonic currents for deep inelastic scattering processes, highlighting the importance of azimuthal asymmetries and cautioning against symmetry assumptions that can lead to inaccuracies in certain measurements.

## Contribution

It provides a simplified representation of leptonic currents and clarifies the conditions under which azimuthal asymmetries are relevant in deep inelastic scattering.

## Key findings

- Azimuthal asymmetries vanish after integration over the azimuthal angle in the boson-proton rest frame.
- Symmetry assumptions may lead to incorrect results when physical quantities are specified in the laboratory frame.
- The paper emphasizes careful consideration of azimuthal asymmetries in experimental analyses.

## Abstract

We present a compact form of the leptonic currents for the computation of the processes involving an initial virtual boson (photon, $W^{\pm}$ or $Z_0$). For deeply inelastic scattering, once the azimuthal angle of the plane expanded by the initial- and final-state leptons are integrated over in the boson-proton rest frame, the azimuthal-asymmetric terms vanish, which, however, is NOT true when some physical quantities (such as the transverse momentum of the observed particle) are specified in laboratory frame. The abuse of the symmetry may lead to wrong results.