Transverse momentum structure of proton within the basis light-front quantization framework

TL;DR

This paper calculates the transverse-momentum-dependent parton distribution functions of the proton using the basis light-front quantization framework, showing consistency with lattice QCD and revealing new insights into TMD independence and $x$-dependence.

Contribution

It introduces a novel calculation of TMD PDFs within the BLFQ framework, demonstrating independence of T-even TMDs and providing detailed $x$-dependence analysis.

Findings

Results agree with lattice QCD calculations.

Six T-even TMDs are independent, contradicting previous model-dependent relations.

Non-trivial $x$-dependence of $ig<(p^ot)^2ig>$ observed.

Abstract

We obtain the leading-twist valence quark transverse-momentum-dependent parton distribution functions (TMD PDFs) for the proton within the basis light-front quantization (BLFQ) framework. Our results are consistent with lattice QCD calculations and our previous results for the collinear limit. We also obtain consistency with the Soffer-type bounds. Within our approach, we find that six T-even TMDs in the leading twist are all independent of each other, and previously found model-dependent relations do not hold. This is a promising sign that our results are representative of future, more extensive treatments of QCD. Furthermore, we obtain a non-trivial $ x $-dependence of the $ \left<(p^\perp)^2\right> $ and some consistency with the Gaussian ansatz but only in the small $ (p^\perp)^2 $ region. Those features suggest our results may be a useful alternative in future experimental extractions.