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

The high precision HERA combined measurement of inclusive deep inelastic cross sections in neutral and charged current $ep$ scattering, corresponding to a luminosity of about 1 fb${}^{{}-1}$, permits searches for new contributions to electron-quark scattering beyond the Standard Model up to TeV scales. A new approach to beyond the Standard Model analysis of the inclusive $ep$ data is presented; simulataneous fits of parton distribution functions and 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.