Flash from the Past: New Gamma-Ray Constraints on Light CP-even Scalar from SN1987A

TL;DR

This paper uses historical gamma-ray data from SN1987A to set new limits on light CP-even scalars, which could be produced in supernovae and decay into detectable gamma rays, refining constraints on their properties.

Contribution

It introduces novel constraints on light CP-even scalars by analyzing old gamma-ray observations from SN1987A, a method not previously employed for this purpose.

Findings

Established new upper bounds on the scalar-Higgs mixing angle.

Excluded certain parameter regions for light CP-even scalars.

Demonstrated the effectiveness of using archival gamma-ray data for particle physics constraints.

Abstract

We derive new constraints on light CP-even scalars using old gamma-ray observations in the direction of SN1987A by the Solar Maximum Mission (SMM) satellite. Light scalars can be abundantly produced in the supernova core via the nucleon bremsstrahlung process, can stream out of the supernova-environment and decay into photons -- either primary photons or secondary photons from lepton-antilepton pairs -- thus leading to a gamma-ray signal. From the non-observation of excess photon flux by SMM after the detection of the neutrino burst from SN1987A, we set new constraints on the mixing angle of the CP-even scalar with the Standard Model Higgs boson.