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

Yue Yu, Writasree Maitra, P. S. Bhupal Dev, Jean-Franccois Fortin, Steven P. Harris, Kuver Sinha, Yongchao Zhang

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.

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

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.
Paper Structure (15 sections, 30 equations, 11 figures)

This paper contains 15 sections, 30 equations, 11 figures.

Table of Contents

  1. Introduction
  2. Scalar Emission from Supernova
  3. Supernova Profile
  4. Decay of Scalar
  5. Reabsorption of Scalar
  6. Photon Flux from Scalar Decay
  7. Direct Photon Production
  8. Secondary Photon Production
  9. Total Differential Photon Fluence
  10. Results
  11. Conclusion
  12. Partial Decay Widths of Scalar $S$
  13. Scalar Emission Rate
  14. Geometry of Scalar Decay
  15. Secondary Photon Spectrum from a Single Scalar Decay

Figures (11)

  • Figure 1: Feynman diagrams for the production of light scalar $S$ in the nucleon bremsstrahlung process $N_1 + N_2 \to N_3 + N_4 +S$ in the supernova core Dev:2020eam, with $N_i$ corresponding to either proton or neutron. The left and right panels are respectively showcasing the $t$ and $u$-channel Feynman diagrams of the concerned process. The light scalar $S$ can be attached to any of the nucleon lines $(a)$, $(b)$, $(c)$, $(d)$, $(a')$, $(b')$, $(c')$, $(d')$, as denoted by the crosses ($\times$), or to the pion mediator $(e)$, $(e')$, as denoted by the blobs ($\bullet$).
  • Figure 2: Snapshots of profiles of the baryon density (left panel) and temperature (right panel) as functions of distance $r$ from the supernova core at various times post core bounce obtained from the Garching 1D CCSN simulation archive garching with the SFHo-20 equation of state.
  • Figure 3: Heat map of the probability of scalars to decay at a distance of $L=R_*=3\times 10^{12}$ cm (left panel) and $L=D=51.4$ kpc (right panel) after being produced in the supernova core.
  • Figure 4: The heatmap of the probability of scalar not being reabsorbed within the neutrinosphere.
  • Figure 5: The time-integrated production rate of scalars as a function of its energy for some benchmark values of the scalar mass.
  • ...and 6 more figures