Constraining axion-like particles with the diffuse gamma-ray flux measured by the Large High Altitude Air Shower Observatory

Abstract

The detection of very high-energy neutrinos by IceCube experiment supports the existence of a comparable gamma-ray counterpart from the same cosmic accelerators. Under the likely assumption that the sources of these particles are of extragalactic origin, the emitted photon flux would be significantly absorbed during its propagation over cosmic distances. However, in the presence of photon mixing with ultra-light axion-like-particles (ALPs), this expectation would be strongly modified. Notably, photon-ALP conversions in the host galaxy would produce an ALP flux which propagates unimpeded in the extragalactic space. Then, the back-conversion of ALPs in the Galactic magnetic field leads to a diffuse high-energy photon flux. In this context, the recent detection of the diffuse high-energy photon flux by the Large High Altitude Air Shower Observatory (LHAASO) allows us to exclude at the $$95\%$$ 95 % CL an ALP-photon coupling $$g_{a\gamma } > rsim 3.9$$ g a γ ≳ 3.9 –$$7.8 \times 10^{-11}~\mathrm {GeV^{-1}}$$ 7.8 × 10 - 11 GeV - 1 for $$m_{a}\lesssim 4\times 10^{-7}~\textrm{eV}$$ m a ≲ 4 × 10 - 7 eV , depending on the assumptions on the magnetic fields and on the original gamma-ray spectrum. This new bound is complementary with other ALP constraints from very-high-energy gamma-ray experiments and sensitivities of future experiments.

On ALP scenarios and GRB 221009A

“…where n e denotes the electron density and B T denotes the strength of the magnetic field in the directions transverse to the propagation. The contribution ∆ CMB account for photon-photon dispersion, and the expression for ∆ CMB is a valid approximation for ω 300 TeV [44,45].…”

Exploring muonphilic ALPs at $μ^+μ^-$ and $μp$ colliders

“…For example, astrophysical observations of the diffuse gamma-ray background provide tight constraints on the coupling strength of sub-eV ALPs to photons [25,26], while experiments based on the LEP and LHC can limit the coupling strength of high-mass ALPs to SM particles [27][28][29][30][31][32]. With the advancement of experimental techniques, these bounds are expected to become even more stringent in the future, offering exciting new prospects to investigate the properties of ALPs.…”