Experimental signatures of Kalb-Ramond-like particles

TL;DR

This paper investigates the experimental signatures and constraints of hypothetical Kalb-Ramond-like particles, modeled as antisymmetric tensors, through their effects on atomic and scattering processes, deriving bounds from collider data.

Contribution

It provides the first comprehensive analysis of phenomenological signatures and experimental bounds for Kalb-Ramond-like particles coupled to fermions.

Findings

Strongest bounds from LEP data at 136.23 GeV: $g_{PV}/\\Lambda \lesssim 6.3 \times 10^{-13} \, \mathrm{eV}^{-1}$

Limits on coupling constants depend on particle mass, with tighter constraints for lighter masses.

Future colliders could improve these bounds with higher energies and better precision.

Abstract

We analyse phenomenological signatures of Kalb-Ramond-like particles, described by an antisymmetric rank-2 tensor, when coupled to fermionic matter. The latter is modelled by a tensor current coupled directly to the Kalb-Ramond field or by a pseudovector current coupled to the rank-1 dual of the field-strength tensor. We obtain limits on the coupling constants to fermions and mass of the Kalb-Ramond-like particles by investigating their impact on the hyperfine splittings of hydrogen, the tree-level unitarity of the $S$ matrix for $e^- + e^+ \rightarrow \ell^- + \ell^+$ scattering with $\ell \neq e$ and the differential cross section for Bhabha scattering. Assuming that the couplings to fermions are independent of the fermion species, the strongest 95\%-CL bounds we find are from LEP data at $\sqrt{s} = 136.23$~GeV, namely $g_{\rm PV}/\Lambda \lesssim 6.3 \times 10^{-13} \, {\rm eV}^{-1}$ and $g_{\rm T} \lesssim 1.3 \times 10^{-12} \left( m/{\rm eV} \right)$, both for $m \ll \sqrt{s}$ (here $\Lambda$ is a characteristic energy scale). These limits can be improved in upcoming lepton colliders due to enhanced precision, as well as higher energies.