Improved stellar limits on a light CP-even scalar

Abstract

We derive improved stellar luminosity limits on a generic light CP-even scalar field S mixing with the Standard Model (SM) Higgs boson from the supernova SN1987A, the Sun, red giants (RGs) and white dwarfs (WDs). For the first time, we include the geometric effects for the decay and absorption of S particles in the stellar interior. For SN1987A and the Sun, we also take into account the detailed stellar profiles. We find that a broad range of the scalar mass and mixing angle can be excluded by our updated astrophysical constraints. For instance, SN1987A excludes 1.0 × 10 −7 sin θ 4.0 × 10 −5 and scalar mass up to 290 MeV, which covers the cosmological blind spot with a high reheating temperature. The updated solar limit excludes the mixing angle in the range of 3.8 × 10 −11 < sin θ < 0.27, with scalar mass up to 39 keV. The RG and WD limits are updated to 4.3 × 10 −13 < sin θ < 8.6 × 10 −5 and 2.3×10 −18 < sin θ < 3.5×10 −8 , with scalar mass up to 398 keV and 292 keV, respectively.

Light scalar explanation for 18 TeV GRB 221009A

“…In this work, we will use the 18 TeV GRB γ-ray flux observation and the number of the detected events in the 2000 second observation window to set new astrophysical bounds. These limits complement the existing bounds derived from stellar cooling and luminosity measurements of the Sun, white dwarfs, red giants and supernovae [57][58][59].…”

“…The bounds obtained from GRB 221009 A by requiring N S γ = 50, 500 and 5000 events complement those given by supernovae [57] and collider exclusions [62,75,76]. Note that considering regions with > 500 or > 50 events, there is no upper bound on mixing.…”

“…We also show the stellar exclusions in Ref. [57] given by the supernova SN1987A using different numerical profiles Fischer 11.8M (blue), Fischer 18M (cyan) [77] and Nakazato 13M (magenta) [78]. We also show the combined collider searches (gray) [62,75,76].…”

“…Refs. [57,66,69]. It should be noted that E S = 2 E γ is fixed simply due to kinematics of two-body decays.…”

“…The shaded regions correspond to supernova exclusions from Ref. [57] from various models such as Fischer 11M (blue), Fischer 18M (cyan) and Nakazato 13M (magenta). Additionally, we add complementary limits from SN1987A and collider searches [62,75,76].…”