Constraints on antisymmetric tensor fields from Bhabha scattering

Siddharth Tiwary,Rainer Dick

doi:10.1140/epjc/s10052-021-09915-x

Abstract

Antisymmetric tensor fields are a compelling prediction of string theory. This makes them an interesting target for particle physics because antisymmetric tensors may couple to electromagnetic dipole moments, thus opening a possible discovery opportunity for string theory. The strongest constraints on electromagnetic dipole couplings would arise from couplings to electrons, where these couplings would contribute to Møller and Bhabha scattering. Previous measurements of Bhabha scattering constrain the couplings to {tilde{M}}_e m_C>7.1times 10^4,{mathrm {GeV}}^2, where m_C is the mass of the antisymmetric tensor field and {tilde{M}}_e is an effective mass scale appearing in the electromagnetic dipole coupling.

Highlights

String theory has become an increasingly complex and compelling framework for particle physics beyond the Standard Model
While supersymmetry and Kaluza–Klein modes were traditionally studied as possible indicators for the correctness of string theory for about half a century the prospects of low-scale string theory added the direct detection of string excitations as a further possibility [4,5,6,7,8,9,10,11,12,13,14]
Antisymmetric tensor fields are unavoidable in string theory and we should study their possible signatures in particle physics experiments

Summary

Introduction

String signatures from Kaluza–Klein modes and Z bosons at the LHC have been studied [15, 16] Both standard string theory and the Kalb–Ramond proposal include couplings of antisymmetric tensor fields Cμν (x) to string world sheets S: X μ(τ, σ ) ≡ X μ(σ 1, σ 2) in the form. Antisymmetric tensor fields are unavoidable in string theory and we should study their possible signatures in particle physics experiments. Antisymmetric tensors can couple in particular to electromagnetic dipole moments, contributing to Møller and Bhabha scattering This is relevant for upcoming or proposed lepton colliders [1,2,21,22], because the well-defined initial state in the scattering events facilitates the search for deviations from Standard Model scattering cross sections.

Bhabha scattering through Kalb–Ramond exchange

Constraints on antisymmetric tensors from Bhabha scattering

Findings

Conclusions