### Regular Series

#### LII Cracow School of Theoretical Physics Astroparticle Physics in the LHC Era

Baryogenesis, Dark Matter and the Maximal Temperature of the Early Universe

Acta Phys. Pol. B 43, 2153 (2012)

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abstract

Mechanisms for the generation of the matter–antimatter asymmetry and dark matter strongly depend on the reheating temperature $T_{\rm R}$, the maximal temperature reached in the early universe. Forthcoming results from the LHC, low energy experiments, astrophysical observations and the Planck satellite will significantly constrain baryogenesis and the nature of dark matter, and thereby provide valuable information about the very early hot universe. At present, a wide range of reheating temperatures is still consistent with observations. We illustrate possible origins of matter and dark matter with four examples: moduli decay, electroweak baryogenesis, leptogenesis in the $\nu$MSM and thermal leptogenesis. Finally, we discuss the connection between baryogenesis, dark matter and inflation in the context of supersymmetric spontaneous $B$–$L$ breaking.

Fermi Large Area Telescope Results: The Sky at High Energies and the Quest for Dark Matter Signals

Acta Phys. Pol. B 43, 2187 (2012)

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abstract

Successfully launched in June 2008, the Fermi Gamma-ray Space Telescope, formerly named GLAST, has been observing the high-energy gamma-ray sky with unprecedented sensitivity in the 20 MeV–300 GeV energy range and electrons $+$ positrons in the 7 GeV–1 TeV range, opening a new observational window on a wide variety of astrophysical objects.

Indirect Dark Matter Detection

Acta Phys. Pol. B 43, 2199 (2012)

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abstract

Dark matter particles could self-annihilate or decay producing a flux of antimatter particles, gamma-rays or neutrinos which could be observed as an excess over their expected astrophysical backgrounds, opening the possibility of indirectly detecting dark matter. In this paper, we will review the calculation of the expected fluxes of Standard Model particles produced in the annihilation or the decay of dark matter particles, as well as the limits on the dark matter properties which follow from observations.

Gravitino and SuperWIMPs in Cosmology

Acta Phys. Pol. B 43, 2225 (2012)

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abstract

We will review models of Dark Matter, where the particle interacts much more weakly than weak, also called SuperWIMPs or E-WIMPs models. One particularly very well known candidate of this type is the gravitino, but also other well-motivated particles are the axino, a sterile neutrino or a particle of the hidden sector with GUT suppressed interaction with normal matter, etc. These candidates have a very different phenomenology than candidates of the weakly interacting type, i.e. WIMPs (Weakly-Interacting Massive Particles), but they can still be produced in cosmology in sufficient number to provide the measured Dark Matter density. Moreover, if they are connected to a larger sector of SM-charged new particles, like in the case of supersymmetric models, they can provide interesting alternative signatures at colliders.

Nonlinear Electromagnetic Forces in Astrophysics

Acta Phys. Pol. B 43, 2237 (2012)

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abstract

Electromagnetism becomes a nonlinear theory having (effective) photon–photon interactions due at least to electron–positron fluctuations in the vacuum. We discuss the consequences of the nonlinearity for the force felt by a charge probe particle, and compare the impact of Euler–Kockel QED effective nonlinearity to the possibility of Born–Infeld-type nonlinearity.

Compact Ultradense Objects in the Solar System

Acta Phys. Pol. B 43, 2251 (2012)

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abstract

We describe properties and gravitational interactions of meteor-mass and greater compact ultra dense objects with nuclear density or greater CUDOs. We discuss possible enclosure of CUDOs in comets and the stability of these objects on impact with the Earth and Sun showing that the hypothesis of a CUDO core helps resolve issues challenging the understanding of a few selected cometary impacts.

From Quark-Gluon Universe to Neutrino Decoupling: $200\lt T\lt 2$ MeV

Acta Phys. Pol. B 43, 2261 (2012)

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abstract

The properties of the quark and hadron Universe are explored. Kinetic theory considerations are presented proving that hadron abundances after phase transformation from quarks to hadrons remain intact till abundances of hadrons become irrelevant. The hadronization process and the evolution of hadron yields are described in detail.

Simulations of Binary Neutron Stars and Black Hole–Torus Systems in General Relativity

Acta Phys. Pol. B 43, 2285 (2012)

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abstract

Merging binary neutron stars are among the strongest known sources of gravitational waves, have features compatible with the events producing short-hard gamma-ray bursts, and might be the long–sought formation sites of high-mass number r-process elements. Numerical relativity has reached a stage where a complete description of the inspiral, merger and post-merger phases of the late evolution of close binary neutron-star systems is possible. This is allowing the systematic investigation of such a many-sided subject. This paper presents an overview of numerical relativity simulations of binary neutron star mergers and the evolution of the resulting black hole–torus systems. Such numerical work is based upon a basic theoretical framework which comprises the Einstein’s equations for the gravitational field and the hydrodynamics equations for the evolution of the matter fields. The most well-established formulations for both systems of equations are briefly discussed, along with the numerical methods best suited for their numerical solution, specifically high-order finite-differencing for the case of the gravitational field equations and high-resolution shock-capturing schemes for the case of the relativistic Euler equations. A number of recent results are reviewed, namely the outcome of the merger depending on the initial total mass and equation of state of the binary, as well as the post-merger evolution phase once a black hole–torus system is produced. Such system has been shown to be subject to non-axisymmetric instabilities leading to the emission of large amplitude gravitational waves.

Screened Modified Gravity

Acta Phys. Pol. B 43, 2307 (2012)

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abstract

The acceleration of the expansion of the Universe has led to the construction of Dark Energy models, where a light scalar field may have a range reaching up to cosmological scales. Screening mechanisms allow these models to evade the tight gravitational tests in the solar system and the laboratory. I will briefly review some of the salient features of screened modified gravity models of the chameleon, dilaton or symmetron types using $f(R)$ gravity as a template.

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