Accessing the nucleon transverse structure in inclusive deep inelastic scattering

Alberto Accardi,Alessandro Bacchetta

doi:10.1016/j.physletb.2017.08.074

Abstract

We revisit the standard analysis of inclusive Deep Inelastic Scattering off nucleons taking into account the fact that on-shell quarks cannot be present in the final state, but they rather decay into hadrons – a process that can be described in terms of suitable “jet” correlators. As a consequence, a spin-flip term associated with the invariant mass of the produced hadrons is generated nonperturbatively and couples to the target's transversity distribution function. In inclusive cross sections, this provides an hitherto neglected and large contribution to the twist-3 part of the g2 structure function, that can explain the discrepancy between recent calculations and fits of this quantity. It also provides an extension of the Burkhardt–Cottingham sum rule, providing new information on the transversity function, as well as an extension of the Efremov–Teryaev–Leader sum rule, suggesting a novel way to measure the tensor charge of the proton.

Highlights

The tensor charge is a fundamental property of the nucleon that is at present poorly constrained but of fundamental importance, not the least because its knowledge can be used to put constraints on searches for physics beyond the Standard Model [1,2,3,4,5]
The new term is proportional to the transversity distribution function multiplied by a new nonperturbative “jet mass”, which will be precisely defined below, and has the interesting features that: (a) it violates the Wandzura–Wilczek relation; (b) it extends the Burkhardt–Cottingham sum rule, providing new useful information on behavior of the transversity distribution; (c) it extends the Efremov–Teryaev–Leader sum rule, providing a novel way to measure the proton’s tensor charge
Motivated by mass corrections to inclusive Deep Inelastic Scattering (DIS) structure functions at large values of the Bjorken invariant xB, Accardi and Qiu [23] have introduced in the LO handbag diagram a “jet correlator”, called “jet factor” by Collins, Rogers, and Stasto in Ref. [24], that accounts for invariant mass production in the current region and ensures that leading twist calculations in collinear factorization are consistent with the xB < 1 requirement imposed by baryon number conservation

Summary

INTRODUCTION

The tensor charge is a fundamental property of the nucleon that is at present poorly constrained but of fundamental importance, not the least because its knowledge can be used to put constraints on searches for physics beyond the Standard Model [1,2,3,4,5]. The new term is proportional to the transversity distribution function multiplied by a new nonperturbative “jet mass”, which will be precisely defined below, and has the interesting features that: (a) it violates the Wandzura–Wilczek relation; (b) it extends the Burkhardt–Cottingham sum rule, providing new useful information on behavior of the transversity distribution; (c) it extends the Efremov–Teryaev–Leader sum rule, providing a novel way to measure the proton’s tensor charge. We estimate this new jet-mass-induced contribution based on a recent extraction of the transversity distribution, and show it can be very large

THE QUARK-QUARK JET CORRELATOR

ΞA l k

TWIST-3 ANALYSIS

THE g2 STRUCTURE FUNCTION

MOMENTS OF THE g2 STRUCTURE FUNCTION

CONCLUSIONS