Probing a Secluded U(1) at B-factories

TL;DR

This paper investigates how B-factory experiments like BaBar and BELLE can detect a secluded U(1) gauge field kinetically mixed with the Standard Model, focusing on multi-lepton signatures from Higgs-strahlung processes.

Contribution

It provides the first detailed analysis of collider signatures of a minimal secluded U(1) model at B-factories, highlighting the potential to probe natural kinetic mixing angles.

Findings

B-factories can effectively probe kinetic mixing angles of 10^(-2) to 10^(-3).

Multi-lepton signatures from Higgs-strahlung are promising signals.

The parameter space relevant for natural models is accessible at current colliders.

Abstract

A secluded U(1) gauge field, kinetically mixed with Standard Model hypercharge, provides a `portal' mediating interactions with a hidden sector at the renormalizable level, as recently exploited in the context of WIMP dark matter. The secluded U(1) symmetry-breaking scale may naturally be suppressed relative to the weak scale, and so this sector is efficiently probed by medium energy electron-positron colliders. We study the collider signatures of the minimal secluded U(1) model, focusing on the reach of B-factory experiments such as BaBar and BELLE. In particular, we show that Higgs-strahlung in the secluded sector can lead to multi-lepton signatures which probe the natural range for the kinetic mixing angle of 10^(-2)-10^(-3) over a large portion of the kinematically accessible parameter space.