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

H Abramowicz,I Abt,O Behnke,U Kötz,E Tassi,K Tokushuku,S Bhadra,M Wing,A Longhin,J Ciborowski,A Bruni,O Kuprash,M Ruspa,E Gallo,I Brock,A Mastroberardino,R Brugnera,D Lontkovskyi,N Kovalchuk,U Karshon,F Mohamad Idris,R Klanner,T Schörner-Sadenius,O Turkot,A Garfagnini,W Słomiński,S Antonelli,D Sukhonos,E Paul,P Stopa,O Zenaiev,O Hlushchenko,A Caldwell,T Nobe,M Ishitsuka,S Yamada,M Turcato,W Perlański,V Myronenko,N Mohammad Nasir,E.G Boos,A Bertolin,M Capua,S Dusini,I Bloch,C Gwenlan,O Shkola,K Wichmann,A Solano,Y Yamazaki,U Klein,S Kananov,I Makarenko,J Sztuk-Dambietz,A Levy,J Tomaszewska,M Corradi,B.O Zhautykov,J Malka,R Hori,P Kaur,R Shevchenko,A Stern,T Tymieniecka,A Gizhko,K Nagano,A Kotański,D Kisielewska,F Januschek,U Behrens,L Adamczyk,M Schioppa,G Grzelak,E Lobodzinska,B Löhr,A Polini,E Lohrmann,N Stefaniuk,M Adamus,A Geiser,L.M Shcheglova,B Foster,W Hain,L Zawiejski,N Zakharchuk,Y Iga,M Lisovyi,S Limentani,D.S Zotkin,R Ciesielski,D Hochman,T Tsurugai,U Schneekloth,V Aushev,B Krupa,M Kuze,H Kowalski,A Verbytskyi,Wan Ahmad Tajuddin Wan Abdullah ,Yu A Golubkov ,R C E Devenish ,N Z Jomhari ,I O Skillicorn ,M P Guzik ,Olga Lukina ,G P Gach ,Inderpal Singh ,J J Chwastowski ,A F Żarnecki ,L K Gladilin ,N H Brook ,Y Onishchuk ,Yu.o Shyrma ,Philipp Roloff ,A M Cooper-Sarkar ,R J Nowak ,R K Dementiev ,L Stančo ,P Bussey ,C D Catterall ,D H Saxon ,B B Levchenko ,Z A Ibrahim ,M Przybycién ,N S Pokrovskiy ,І Каденко ,I A Korzhavina

doi:10.1016/j.physletb.2016.04.007

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.

Highlights

Precision measurements of deep inelastic e±p scattering (DIS) cross sections at high values of negative four-momentum-transfer squared, Q2, allow searches for contributions beyond the Standard Model (BSM), even far beyond the centre-of-mass energy of the e±p interactions
The results of the limit-setting procedure using the simultaneous fit to parton distribution function (PDF) parameters and Rq2, based on sets of Monte Carlo replicas testing the possible cross-section modifications due to a quark form factor, yield the 95% C.L. limits on the effective quark radius of
Taking into account the possible influence of quark radii on the PDF parameters is necessary as demonstrated in Figs. 1 and 2, because the limits that would be obtained for fixed PDF parameters are too strong by about 10%

Summary

Introduction

Precision measurements of deep inelastic e±p scattering (DIS) cross sections at high values of negative four-momentum-transfer squared, Q2, allow searches for contributions beyond the Standard Model (BSM), even far beyond the centre-of-mass energy of the e±p interactions. The inclusive cross sections were used as input to a QCD analysis within the DGLAP formalism, resulting in a PDF set denoted as HERAPDF2.0. For the CI analysis presented here, in which the data are identical to those used for the HERAPDF2.0 determination and the statistical uncertainties are no longer dominant, a new procedure to set limits on the BSM model contributions is required.

Results

Conclusion