Probing dark-axionlike particle portals at future e+e− colliders

Sanjoy Biswas,Emidio Gabrielli,Anirban Chatterjee,Barbara Mele

doi:10.1103/physrevd.100.115040

Abstract

We study portal interactions connecting visible and dark sectors, and involving local interactions of a photon, a dark photon and a axion-like particle (ALP) at future $e^+e^-$ colliders. These interactions, mediated by higher-dimensional effective operators, may arise at one-loop by kinetic mixing between dark and ordinary photons, or, for massless dark photons, by direct short-distance contributions. We explore these portal interactions for a heavy ALP with masses between about 10 GeV and 230 GeV by investigating the sensitivity of the production $e^+e^- \to \gamma \gamma \bar{\gamma}$ to the effective couplings, where the dark photon $\bar\gamma$ gives rise to missing momentum in the final state. We will show how an appropriate choice of missing-energy and missing-mass cuts can optimize the signal to standard-model background ratio. Exclusion regions for the effective photon-dark-photon-ALP couplings versus the ALP mass are worked out for a few representative values of the collision energy and integrated luminosity, as presently envisaged by future $e^+e^-$ projects.

Highlights

The persistent global consistency of the Standard Model (SM) predictions against the data collected so far at the CERN Large Hadron Collider (LHC) is radically changing our perspective on the origin of possible new physics beyond the SM, and on its characteristic energy scale
These interactions, mediated by higher-dimensional effective operators, may arise at one loop by kinetic mixing between dark and ordinary photons, or, for massless dark photons, by direct short-distance contributions. We explore these portal interactions for a heavy axionlike particle (ALP) with masses between about 10 and 230 GeV, and for a massless dark photon, by investigating the sensitivity of the production eþe− → γγγto the effective couplings, where the dark photon γgives rise to missing momentum in the final state
We have considered an axionlike particle with mass in the range (10–230) GeV, coupled to a photon and a massless dark photon through higher-dimensional effective operators

Summary

INTRODUCTION

The persistent global consistency of the Standard Model (SM) predictions against the data collected so far at the CERN Large Hadron Collider (LHC) is radically changing our perspective on the origin of possible new physics beyond the SM, and on its characteristic energy scale. Most of present dark-photon searches focus on massive dark photons, where the broken Uð1ÞD gauge field naturally develops by kinetic mixing a treelevel (millicharged) interaction with ordinary charged matter [8]. The DS could contain the so-called axionlike particles (ALPs), a, loosely referring to neutral light (or ultralight) scalar (or pseudoscalar) particles These particles can be present in SM extensions motivated by the solution to the strong charge-parity (CP) symmetry problem (in which case the ALP is a QCD axion [17]) or can be pseudoNambu-Goldstone bosons corresponding to spontaneously broken continuous symmetries, either in the visible or in the DS, or a moduli field in string models [18,19,20,21].

THEORETICAL FRAMEWORK

LEP analysis

RESULTS AND DISCUSSION

SUMMARY AND CONCLUSIONS