Search for Compositeness, Leptoquarks and Large Extra Dimensions in eq Contact Interactions at HERA

TL;DR

This study analyzes high-energy electron-proton scattering data from HERA to search for signs of new physics such as compositeness, leptoquarks, and extra dimensions, but finds no evidence and sets limits on various models.

Contribution

It provides the first limits on contact interactions, leptoquarks, and large extra dimensions using HERA data at high momentum transfers.

Findings

No evidence for new phenomena was observed.

Limits were set on compositeness scales and leptoquark masses.

Constraints on models of large extra dimensions were established.

Abstract

The reaction e+p --> e+X is studied with the H1 detector at Hera. The data cover momentum transfers Q^2 between 200 GeV^2 and 30,000 GeV^2 and correspond to an integrated luminosity of 35.6 pb^(-1). The differential cross section dsigma/dQ^2 is compared to the Standard Model expectation for neutral current scattering and analysed to search for bar(e)e bar(q)q contact interactions. No evidence for new phenomena is observed. The results are used to set limits on scales within models of electron--quark compositeness, quark form factors and the exchange of virtual heavy leptoquarks. A search for gravitational effects mediated through the exchange of virtual gravitons which propagate into large extra dimensions is presented.