We provide a simple proof of why the Love number vanishes for extremal Reissner-Nordstrøm and Kerr-Newman black holes. The argument is based on a conformal inversion isometry of the spacetime connecting the horizon with large distances.

Greece

Alex Kehagias

Switzerland

Davide Perrone

Antonio Riotto

A short note on the Love number of extremal Reissner-Nordstrøm and Kerr-Newman black holes

We consider the role of secondary infall and accretion onto an initially overdense perturbation in matter-dominated eras, like the one which is likely to follow the end of inflation. We show that primordial black holes may form through post-collapse accretion, namely the accretion onto an initial overdensity whose collapse has not given rise to a primordial black hole. Accretion may be also responsible for the growth of the primordial black hole masses by orders of magnitude till the end of the matter-dominated era.

Valerio De Luca

Italy

Gabriele Franciolini

Paolo Pani

Primordial black holes in matter-dominated eras: The role of accretion

Making use of both the stochastic approach to the tunneling phenomenon and the threshold statistics, we offer a simple argument to show that critical bubbles may be correlated in first-order phase transitions and biased compared to the underlying scalar field spatial distribution. This happens though only if the typical energy scale of the phase transition is sufficiently high. We briefly discuss possible implications of this result, e.g., the formation of primordial black holes through bubble collisions.

Bubble correlation in first-order phase transitions

We calculate the formation probability of primordial black holes generated during the collapse at horizon re-entry of large fluctuations produced during inflation, such as those ascribed to a period of ultra-slow-roll. We show that it interpolates between a Gaussian at small values of the average density contrast and a Cauchy probability distribution at large values. The corresponding abundance of primordial black holes may be larger than the Gaussian one by several orders of magnitude. The mass function is also shifted towards larger masses.

Matteo Biagetti

The formation probability of primordial black holes

We correct the mistakes in the original version of the paper and recalculate the relevant bounds on the Z′-mediated DM. The mistakes of the published version have to do with the calculation of the annihilation cross sections.

Thomas Jacques

CERN

Andrey Katz

Enrico Morgante

Davide Racco

Mohamed Rameez

Erratum to: Complementarity of DM searches in a consistent simplified model: the case of Z′

We discuss a new interaction for chiral models in four-dimensional  <math><mi>N</mi></math> $$ \mathcal{N} $$ = 1 supergavity. It contains a new arbitrary function in addition to the Kähler potential and superpotential. Its features include linearly realized off-shell supersymmetry, Kähler-Weyl invariance and broken supersymmetry. The corresponding scalar potential is augmented by the arbitrary function which allows freedom in constructing low-energy phenomenological models and inflationary models rooted in supergravity.

Belgium

Fotis Farakos

Liberated  <math><mi>N</mi></math> $$ \mathcal{N} $$ = 1 supergravity

We show that the minimal D = 5, N $$ \mathcal{N} $$ = 2 gauged supergravity set-up may encode naturally the recently proposed clockwork mechanism. The minimal embedding requires one vector multiplet in addition to the supergravity multiplet and the clockwork scalar is identified with the scalar in the vector multiplet. The scalar has a two-parameter potential and it can accommodate the clockwork, the Randall-Sundrum and a no-scale model with a flat potential, depending on the values of the parameters. The continuous clockwork background breaks half of the original supersymmetries, leaving a D = 4, N $$ \mathcal{N} $$ = 1 theory on the boundaries. We also show that the generated hierarchy by the clockwork is not exponential but rather power law. The reason is that four-dimensional Planck scale has a power-law dependence on the compactification radius, whereas the corresponding KK spectrum depends on the logarithm of the latter.

The clockwork supergravity

We investigate the recently proposed clockwork mechanism delivering light degrees of freedom with suppressed interactions and show, with various examples, that it can be efficiently implemented in inflationary scenarios to generate flat inflaton potentials and small density perturbations without fine-tunings. We also study the clockwork graviton in de Sitter and, interestingly, we find that the corresponding clockwork charge is site-dependent. As a consequence, the amount of tensor modes is generically suppressed with respect to the standard cases where the clockwork set-up is not adopted. This point can be made a virtue in resurrecting models of inflation which were supposed to be ruled out because of the excessive amount of tensor modes from inflation.

Clockwork inflation

We propose a novel mechanism for production of baryonic asymmetry in the early Universe. The mechanism takes advantage of the strong first order phase transition that produces runaway bubbles in the hidden sector that propagate almost without friction with ultra-relativistic velocities. Collisions of such bubbles can non-thermally produce heavy particles that further decay out-of-equilibrium into the SM and produce the observed baryonic asymmetry. This process can proceed at the very low temperatures, providing a new mechanism of post-sphaleron baryogenesis. In this paper we present a fully calculable model which produces the baryonic asymmetry along these lines as well as evades all the existing cosmological constraints. We emphasize that the Gravitational Waves signal from the first order phase transition is completely generic and can potentially be detected by the future eLISA interferometer. We also discuss other potential signals, which are more model dependent, and point out the unresolved theoretical questions related to our proposal.

Baryogenesis and gravitational waves from runaway bubble collisions

We analyze the constraints from direct and indirect detection on fermionic Majorana Dark Matter (DM). Because the interaction with the Standard Model (SM) particles is spin-dependent, a priori the constraints that one gets from neutrino telescopes, the LHC, direct and indirect detection experiments are comparable. We study the complementarity of these searches in a particular example, in which a heavy Z ′ mediates the interactions between the SM and the DM. We find that for heavy dark matter indirect detection provides the strongest bounds on this scenario, while IceCube bounds are typically stronger than those from direct detection. The LHC constraints are dominant for smaller dark matter masses. These light masses are less motivated by thermal relic abundance considerations. We show that the dominant annihilation channels of the light DM in the Sun and the Galactic Center are either      <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> </math>  $$ b\overline{b} $$  or      <math> <mi>t</mi> <mover> <mi>t</mi> <mo>¯</mo> </mover> </math>  $$ t\overline{t} $$ , while the heavy DM annihilation is completely dominated by Zh channel. The latter produces a hard neutrino spectrum which has not been previously analyzed. We study the neutrino spectrum yielded by DM and recast IceCube constraints to allow proper comparison with constraints from direct and indirect detection experiments and LHC exclusions.