相关论文: Limits on possible magnetic fields at nucleosynthe…

In the pass from classical to modern physics, the idea of supposing some quantities having distinct or bounded values and keeping the rest continuous has been useful in treating many problems. In this paper, we suppose an upper limit for…

We review current ideas on the origin of galactic and extragalactic magnetic fields. We begin by summarizing observations of magnetic fields at cosmological redshifts and on cosmological scales. These observations translate into constraints…

A computation of nucleosynthesis bounds on the masses of long-lived Dirac and Majorana neutrinos is reviewed. In particular an explicit treatment of the ``differential heating'' of the $\nue$ and $\bnue$ ensembles due to the residual…

As electromagnetic showers may alter the abundance of Helium, Lithium, and Deuterium, we can place severe constraints on the lifetime and amount of electromagnetic energy injected by long-lived particles. Considering up-to-date measurements…

We have arrived at tight constraints on the photon charge, giving comparable bounds, one based on the dominance by dark energy at the present epoch, and the other based on the requirement that early universe nucleosynthesis not be affected…

We discuss the amplification of magnetic fields by the small-scale dynamo, a process that could efficiently produce strong magnetic fields in the first galaxies. In addition, we derive constraints on the primordial field strength from the…

Gravitational wave production induces a strong constraint on the amplitude of a primordial magnetic field. It has been shown that the nucleosynthesis bound for a stochastic gravitational wave background implies that causally generated…

Magnetic fields are considered to be dominant when $\epsilon_{B}\geq\epsilon_{K}$, being $\epsilon_{B}=B^{2}/8\pi$ the magnetic energy density and $\epsilon_{K}=1/2 \rho\theta^{2}$ the rotation energy density, for a conventional moderate B=…

Very strong magnetic fields can arise in non-central heavy-ion collisions at ultrarelativistic energies, which may not decay quickly in a conducting plasma. We carry out relativistic magnetohydrodynamics (RMHD) simulations to study the…

We explore the possibility that matter bulk flows could generate the required vorticity in the electron-proton-photon plasma to source cosmic magnetic fields through the Harrison mechanism. We analyze the coupled set of perturbed Maxwell…

The upper bound on the number of relativistic species present at nucleosynthesis has been used to constrain particles with electric charge $\epsilon e$ ($10^{-8} < \epsilon <1$). We correct the bound previously calculated for milli-charged…

Using the exact propagators in a constant magnetic field, the neutrino self-energy has been calculated to all orders in the field strength $B$ within the minimal extension of the Weinberg-Salam model with massive Dirac neutrinos. A neutrino…

Recent discussion on the possibility to obtain more stringent bounds on neutrino magnetic moment has stimulated new interest to possible effects induced by neutrino magnetic moment. In particular, in this note after a short review on…

It is widely believed that primordial magnetic fields are dramatically diluted by the expansion of the universe. As a result, cosmological magnetic fields with residual strengths of astrophysical relevance are generally sought by going…

We present new simulations of decaying hydromagnetic turbulence for a relativistic equation of state relevant to the early universe. We compare helical and nonhelical cases either with kinetically or magnetically dominated initial fields.…

Motivated by the evidence for a finite neutrino mass we examine anew the interaction of neutrinos in a magnetic field. We present the rate for radiative scattering for both massless and massive neutrinos in the standard model and give the…

Neutrino interactions play a central role in transport and flavor evolution in the ejecta of binary neutron star mergers. Simulations suggest that neutron star mergers may produce magnetic fields as strong as $10^{17}$ G, but computational…

Very-high energy observations of blazars can be used to constrain the strength of the intergalactic magnetic field. A simplifying assumption which is often made is that of a magnetic field of constant strength composed by randomly oriented…

In the presence of an electromagnetic (EM) field the space-time metrics are affected by the field potential. The principle of superposition, which usually rules EM fields, is no longer valid for the biggest fields and Maxwell's equations,…

There are at present more then 30 theories about the origin of cosmic magnetic fields at galactic and intergalactic scales. Most of them rely on concepts of elementary particle physics, like phase transitions in the early Universe, string…