We examine how the existence of a population of primordial black holes (PBHs)
influences cosmological gravitational particle production (CGPP) for spin-0 and
spin-1 particles. In addition to the ...known effects of particle production and
entropy dilution resulting from PBH evaporation, we find that the generation of
dark matter (DM) through CGPP is profoundly influenced by a possible era of PBH
matter domination. This early matter dominated era results in an enhancement of
the particle spectrum from CGPP. Specifically, it amplifies the peak comoving
momentum $k_\star$ for spin-1 DM, while enhancing the plateau of the spectrum
for minimally coupled spin-0 particles for low comoving momenta. At the same
time, the large entropy dilution may partially or completely compensate for the
increase of the spectrum and strongly mitigates the DM abundance produced by
CGPP. Our results show that, in the computation of the final abundance, CGPP
and PBH evaporation cannot be disentangled, but the parameters of both sectors
must be considered together to obtain the final result. Furthermore, we explore
the potential formation of PBHs from density fluctuations arising from CGPP and
the associated challenges in such a scenario.
Axionlike particles are among the most studied extensions of the standard model. In this Letter we study the bounds that the ArgoNeuT experiment can put on the parameter space of two specific ...scenarios: leptophilic axionlike particles and Majorons. We find that such bounds are currently the most constraining ones in the (0.2 - 1.7) GeV mass range.
In the usual quantum field theoretical approach, neutrino oscillations are studied diagonalising either the mass or matter Hamiltonians. In this paper we analyse the problem from an on-shell ...amplitude perspective, where Lagrangians or Hamiltonians are not available. We start by studying in detail how flavor enters in the amplitudes and how the PMNS matrix emerges. We then analyse the elastic amplitude of two neutrinos and two charged leptons that induce matter effects and propose a strategy to obtain the known results of the standard oscillation theory without Hamiltonians. Finally, we extend the previously proposed procedure and use the most general elastic 4-point amplitude to study beyond the Standard Model effects on oscillations.
Dark Photon bounds in the dark EFT Barducci, Daniele; Bertuzzo, Enrico; Giovanni Grilli di Cortona ...
arXiv.org,
11/2021
Paper, Journal Article
Odprti dostop
Dark photons are massive abelian gauge bosons that interact with ordinary photons via a kinetic mixing with the hypercharge field strength tensor. This theory is probed by a variety of different ...experiments and limits are set on a combination of the dark photon mass and kinetic mixing parameter. These limits can however be strongly modified by the presence of additional heavy degrees of freedom. Using the framework of dark effective field theory, we study how robust are the current experimental bounds when these new states are present. We focus in particular on the possible existence of a dark dipole interaction between the Standard Model leptons and the dark photon. We show that, under certain assumptions, the presence of a dark dipole modifies existing supernovæ bounds for cut-off scales up to \(\mathcal{O}(10 - 100~\text{TeV})\). On the other hand, terrestrial experiments, such as LSND and E137, can probe cut-off scales up to \(\mathcal{O}(3~\text{TeV})\). For the latter experiment we highlight that the bound may extend down to vanishing kinetic mixing.
