Related papers: Stellar cooling bounds on new light particles: pla…
We study the recent \XeT excess in context of solar scalar, specifically in the framework of Higgs-portal and the relaxion model. We show that $m_\phi = 1.9\,\keV$ and $g_{\phi e}=2.4\times 10^{-14}$ can explain the observed excess in…
We study warm Higgs portal dark matter (DM) in the framework of freeze-in at stronger coupling. This scenario assumes that the Standard Model thermal bath temperature has always been relatively low, which suppresses dark matter production.…
We investigate a concrete scenario of a light scalar with a mass around 1 MeV which can be connected to the origin of neutrino masses and simultaneously survive current bounds on relativistic degrees of freedom in the early universe. In…
Cooling simulations of neutron stars and their comparison with the data from thermally emitting x-ray sources put constraints on the properties of axions, and by extension of any light pseudoscalar dark matter particles, whose existence has…
We address a method of limiting neutron-mirror neutron mixing ($\epsilon_{nn'}$) by analyzing its effect on neutron star (NS) heating. This method employs observational bounds on the surface temperature of NSs to constrain $\epsilon_{nn'}$.…
The pseudoscalar-photon mixing in presence of large scale magnetic field induces polarization in light from distant cosmological sources. We study the effect of these pseudoscalars or axion like particles (ALPs) on Cosmic Microwave…
The cooling of a young bare strange star is studied numerically by solving the equations of energy conservation and heat transport for both normal and superconducting strange quark matter inside the star. We show that the thermal luminosity…
It has been suggested that a sterile neutrino \nu_s which mixes with standard neutrinos can form nonthermal ``cool'' Dark Matter if its mass and mixing angle fall in the ranges 0.1 keV \lsim m_s \lsim 10 keV and 10^{-10} \lsim \sin^2 \theta…
We present new supernova (SN 1987A) cooling bounds on sub-MeV fermionic dark matter with effective couplings to electrons. These bounds probe the parameter space relevant for direct detection experiments in which dark matter can be absorbed…
Stellar evolution considerations are of fundamental importance in our understanding of the axion/ALP-photon coupling, g_{a\gamma}. Helium burning stars are the best laboratories to study this coupling. Here, we will review the bounds from…
We derive a bound on dark photon dark matter scenarios where the dark photon mass is generated through the Higgs mechanism, based on the requirement that symmetry breaking must occur sufficiently early in the universe. We emphasize that…
The couplings of Higgs particles to two photons are analyzed in the threshold region, where the Higgs mass is about twice the loop--particle mass leading to possible bound state formation. The amplitude of the pseudoscalar decay $A\to…
Binary neutron star mergers provide a laboratory for probing fundamental physics through their gravitational-wave emission and electromagnetic counterparts. In particular, they may allow us to explore signatures of physics beyond the…
We study how light scalar fields can change the stellar landscape by triggering a new phase of nuclear matter. Scalars coupled to nucleons can develop a non-trivial expectation value at finite baryon density. This sourcing of a scalar…
Dark matter produced from thermal freeze-out is typically restricted to have masses above roughly 1 MeV. However, if the couplings are small, the freeze-in mechanism allows for production of dark matter down to keV masses. We consider dark…
We study the upper limits on the mass of the lightest and second lightest CP even Higgs bosons in the (M+1)SSM, the MSSM extended by a gauge singlet. The dominant two loop contributions to the effective potential are included, which reduce…
We re-examine solar emission of hidden photons gamma' (mass m) caused by kinetic mixing. We calculate the emission rate with thermal field theory methods and with a kinetic equation that includes "flavor oscillations" and photon absorption…
In this work, we present UV completions of the recently proposed number-changing Co-SIMP freeze-out mechanism. In contrast to the standard cannibalistic-type dark matter picture that occurs entirely in the dark sector, the $3\to 2$ process…
The implications of hyperon pairing for the thermal evolution of neutron stars containing hyperons are investigated. The outcome of cooling simulations are compared for neutron star models composed only of nucleons and leptons, models…
We explore the cosmological consequences of kinetically mixed dark photons with a mass between 1 MeV and 10 GeV, and an effective electromagnetic fine structure constant as small as $10^{-38}$. We calculate the freeze-in abundance of these…