Limits on the effective quark radius from inclusive $ep$ scattering at HERA

TL;DR

This paper uses high-precision HERA data to set new upper limits on the effective quark radius, exploring potential beyond Standard Model physics through simultaneous fits of parton distributions and new physics contributions.

Contribution

It introduces a novel analysis method combining parton distribution functions with new physics models to constrain quark size using inclusive ep scattering data.

Findings

95% C.L. upper limit on quark radius: 0.43×10^{-16} cm

New analysis approach for beyond Standard Model searches in ep scattering

Constraints improve previous bounds on quark substructure

Abstract

The high-precision HERA data allows searches up to TeV scales for Beyond the Standard Model contributions to electron-quark scattering. Combined measurements of the inclusive deep inelastic cross sections in neutral and charged current $ep$ scattering corresponding to a luminosity of around 1 fb$^{-1}$ have been used in this analysis. A new approach to the beyond the Standard Model analysis of the inclusive $ep$ data is presented; simultaneous fits of parton distribution functions together with contributions of "new physics" processes were performed. Results are presented considering a finite radius of quarks within the quark form-factor model. The resulting 95% C.L. upper limit on the effective quark radius is $0.43\cdot 10^{-16}$ cm.