Intergalactic magnetic fields from first-order phase transitions

Abstract

We study the generation of intergalactic magnetic fields in two models for firstorder phase transitions in the early Universe that have been studied previously in connection with the generation of gravitational waves (GWs): the Standard Model supplemented by an |H| 6 operator (SM+H 6 ) and a classically scale-invariant model with an extra gauged U(1) B − L symmetry (SM B−L ). We consider contributions to magnetic fields generated by bubble collisions and by turbulence in the primordial plasma, and we consider the hypotheses that helicity is seeded in the gauge field or kinetically. We study the conditions under which the intergalactic magnetic fields generated may be larger than the lower bounds from blazar observations, and correlate them with the observability of GWs and possible collider signatures. In the SM+H 6 model bubble collisions alone cannot yield large enough magnetic fields, whereas turbulence may do so. In the SM B−L model bubble collisions and turbulence may both yield magnetic fields above the blazar bound unless the B−L gauge boson is very heavy. In both models there may be observable GW and collider signatures if sufficiently large magnetic fields are generated.

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“…Examples include extended electroweak sectors, effective field theories with higher-dimensional operators and hidden-sector interactions. Extended electroweak models have attracted particular interest by providing options for electroweak baryogenesis and magnetogenesis: see, e.g., [57], and offer opportunities for correlating cosmological observables with signatures at particle colliders [58,59]. The left panel of Fig.…”

Dynamic scale anomalous transport in QCD with electromagnetic background

“…We emphasize again that strong EM fields can be generated in heavy ion collision experiments [28][29][30][31][32][33][34] and in early universe [35][36][37][38][39], where the former is due to the relativistic motion of the colliding nuclei and the smallness of the system, while the latter is, say, due to some primordial (electroweak) phase transitions of strong first order.…”

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“…Note, however, that the magnetic field depends on gradients of Φ. Other possible scenarios may be found in [106], with the general conclusion that magnetic fields of up to ∼10 −11 G on scales of ∼10 kpc are possible [59].…”