A model for fluctuating inflaton coupling: (s)neutrino induced adiabatic perturbations and non-thermal leptogenesis

We discuss an unique possibility of generating adiabatic density perturbations and leptogenesis from the spatial fluctuations of the inflaton decay rate. The key assumption is that the initial isocurvature perturbations are created in the right handed sneutrino sector during inflation which is then converted into adiabatic perturbations when the inflaton decays. We discuss distinct imprints on the cosmic micro wave background radiation, which can distinguish non-thermal versus thermal leptogenesis.Comment: 4 pages, version to be published in PR

Numerical simulations of fragmentation of the Affleck-Dine condensate

We present numerical simulations of fragmentation of the Affleck-Dine condensate in two spatial dimensions. We argue analytically that the final state should consist of both Q-balls and anti-Q-balls in a state of maximum entropy, with most of the balls small and relativistic. Such a behaviour is found in simulations on a 100x100 lattice with cosmologically realistic parameter values. During fragmentation process, we observe filament-like texture in the spatial distribution of charge. The total charge in Q-balls is found to be almost equal to the charge in anti-Q-balls and typically orders of magnitude larger than charge asymmetry. Analytical considerations indicate that, apart from geometrical factors, the results of the simulated two dimensional case should apply also to the fully realistic three dimensional case.Comment: 28 pages, 39 figure

Solitosynthesis of Q-balls

We study the formation of Q-balls in the early universe, concentrating on potentials with a cubic or quartic attractive interaction. Large Q-balls can form via solitosynthesis, a process of gradual charge accretion, provided some primordial charge assymetry and initial ``seed'' Q-balls exist. We find that such seeds are possible in theories in which the attractive interaction is of the form $A H \psi^* \psi$, with a light ``Higgs'' mass. Condensate formation and fragmentation is only possible for masses $m_\psi$ in the sub-eV range; these Q-balls may survive untill present.Comment: 9 pages, 1 figur

Effect of Background Evolution on the Curvaton Non-Gaussianity

We investigate how the background evolution affects the curvature perturbations generated by the curvaton, assuming a curvaton potential that may deviate slightly from the quadratic one, and parameterizing the background fluid density as \rho\propto a^{-\alpha}, where a is the scale factor, and \alpha depends on the background fluid. It turns out that the more there is deviation from the quadratic case, the more pronounced is the dependence of the curvature perturbation on \alpha. We also show that the background can have a significant effect on the nonlinearity parameters f_NL and g_NL. As an example, if at the onset of the curvaton oscillation there is a dimension 6 contribution to the potential at 5 % level and the energy fraction of the curvaton to the total one at the time of its decay is at 1 %, we find variations \Delta f_NL \sim \mathcal{O}(10) and \Delta g_NL \sim \mathcal{O}(10^4) between matter and radiation dominated backgrounds. Moreover, we demonstrate that there is a relation between f_NL and g_NL that can be used to probe the form of the curvaton potential and the equation of state of the background fluid.Comment: 14 pages, 8 figure

Scale-dependence of Non-Gaussianity in the Curvaton Model

We investigate the scale-dependence of f_NL in the self-interacting curvaton model. We show that the scale-dependence, encoded in the spectral index n_{f_NL}, can be observable by future cosmic microwave background observations, such as CMBpol, in a significant part of the parameter space of the model. We point out that together with information about the trispectrum g_NL, the self-interacting curvaton model parameters could be completely fixed by observations. We also discuss the scale-dependence of g_NL and its implications for the curvaton model, arguing that it could provide a complementary probe in cases where the theoretical value of n_{f_NL} is below observational sensitivity.Comment: 14 pages, 5 figures, Eq.(10) correcte

Determination of the freeze-out temperature by the isospin thermometer

The high-resolution spectrometer FRS at GSI Darmstadt provides the full isotopic and kinematical identification of fragmentation residues in relativistic heavy-ion collisions. Recent measurements of the isotopic distribution of heavy projectile fragments led to a very surprising new physical finding: the residue production does not lose the memory of the N/Z of the projectile ending up in a universal de-excitation corridor; an ordering of the residues in relation to the neutron excess of the projectile has been observed. These unexpected features can be interpreted as a new manifestation of multifragmentation. We have found that at the last stage of the reaction the temperature of the big clusters subjected to evaporation is limited to a universal value. The thermometer to measure this limiting temperature is the neutron excess of the residues.Comment: 8 pages, 6 figures, corrected some misprints in the abstract, to be published in "Yadernaya Fizika" as a proceeding of the "VII International School Seminar on Heavy-Ion Phyics", Dubna (Russia), May 27 - June 1, 200

Production of Neutron-rich Heavy Residues and the Freeze-out Temperature in the Fragmentation of Relativistic 238U Projectiles Determined by the Isospin Thermometer

Isotope yields of heavy residues produced in collisions of 238U with lead at 1AGeV show indications for a simultaneous break-up process. From the average N-over-Z ratio of the final residues up to Z = 70, the average limiting temperature of the break-up configuration at freeze out was determined to T approximately 5 MeV using the isospin-thermometer method. Consequences for the understanding of other phenomena in highly excited nuclear systems are discussed.Comment: 22 pages, 9 figures, accepted by Nucl. Phys.

Q-ball formation: Obstacle to Affleck-Dine baryogenesis in the gauge-mediated SUSY breaking ?

We consider the Affleck-Dine baryogenesis comprehensively in the minimal supersymmetric standard model with gauge-mediated supersymmetry breaking. Considering the high temperature effects, we see that the Affleck-Dine field is naturally deformed into the form of the Q ball. In the natural scenario where the initial amplitude of the field and the A-terms are both determined by the nonrenormalizable superpotential, we obtain only very a narrow allowed region in the parameter space in order to explain the baryon number of the universe for the case that the Q-ball formation occurs just after baryon number production. Moreover, most of the parameter sets suited have already been excluded by current experiments. We also find new situations in which the Q-ball formation takes place rather late compared with baryon number creation. This situation is more preferable, since it allows a wider parameter region for naturally consistent scenarios, although it is still difficult to realize in the actual cosmological scenario.Comment: 27 pages, RevTeX, 21 postscript figures included. The version to be publishe

Non-metric chaotic inflation

We consider inflation within the context of what is arguably the simplest non-metric extension of Einstein gravity. There non-metricity is described by a single graviscalar field with a non-minimal kinetic coupling to the inflaton field $\Psi$, parameterized by a single parameter $\gamma$. We discuss the implications of non-metricity for chaotic inflation and find that it significantly alters the inflaton dynamics for field values $\Psi \gtrsim M_P/\gamma$, dramatically changing the qualitative behaviour in this regime. For potentials with a positive slope non-metricity imposes an upper bound on the possible number of e-folds. For chaotic inflation with a monomial potential, the spectral index and the tensor-to-scalar ratio receive small corrections dependent on the non-metricity parameter. We also argue that significant post-inflationary non-metricity may be generated.Comment: 7 pages, 1 figur

Non-Gaussianity from Instant and Tachyonic Preheating

We study non-Gaussianity in two distinct models of preheating: instant and tachyonic. In instant preheating non-Gaussianity is sourced by the local terms generated through the coupled perturbations of the two scalar fields. We find that the non-Gaussianity parameter is given by $f_{NL}^{\phi}\sim 2g < O(1)$, where $g$ is a coupling constant, so that instant preheating is unlikely to be constrained by WMAP or Planck. In the case of tachyonic preheating non-Gaussianity arises solely from the instability of the tachyon matter and is found to be large. We find that for single field inflation the present WMAP data implies a bound $V_{0}^{1/4}/M_{P}\leq 10^{-4}$ on the scale of tachyonic instability. We argue that the tachyonic preheating limits are useful also for string-motivated inflationary models.Comment: 12 pages, 1 figure, additional discussion, improved constraint on the scale of tachyonic preheatin