118359212
Generic inference of inflation models by non-Gaussianity and primordial power spectrum reconstruction
We present a generic inference method for inflation models from observational data by the usage of higher-order statistics of the curvature perturbation on uniform density hypersurfaces. This method is based on the calculation of the posterior for the primordial non-Gaussianity parameters fNL and gNL, which in general depend on specific parameters of inflation and reheating models, and enables to discriminate among the still viable inflation models. To keep analyticity as far as possible to dispense with numerically expensive sampling techniques a saddle-point approximation is introduced, whose precision is validated for a numerical toy example. The mathematical formulation is done in a generic way so that the approach remains applicable to cosmic microwave background data as well as to large scale structure data. Additionally, we review a few currently interesting inflation models and present numerical toy examples thereof in two and three dimensions to demonstrate the efficiency of the higher-order statistics method. A second quantity of interest is the primordial power spectrum. Here, we present two Bayesian methods to infer it from observational data, the so called critical filter and an extension thereof with smoothness prior, both allowing for a non-parametric spectrum reconstruction. These methods are able to reconstruct the spectra of the observed perturbations and the primordial ones of curvature perturbation even in case of non-Gaussianity and partial sky coverage. We argue that observables like T- and B-modes permit to measure both spectra. This also allows to infer the level of non-Gaussianity generated since inflation.
118464550
Self-protection of massive cosmological gravitons
Relevant deformations of gravity present an exciting window of opportunity to probe the rigidity of gravity on cosmological scales. For a single-graviton theory, the leading relevant deformation constitutes a graviton mass term. In this paper, we investigate the classical and quantum stability of massive cosmological gravitons on generic Friedman backgrounds. For a Universe expanding towards a de Sitter epoch, we find that massive cosmological gravitons are self-protected against unitarity violations by a strong coupling phenomenon.
37247936
Degravitation of the cosmological constant and graviton width
We study the possibility of decoupling gravity from the vacuum energy. This is effectively equivalent to promoting Newton's constant to a high-pass filter that degravitates sources of characteristic wavelength larger than a certain macroscopic (super) horizon scale L. We study the underlying physics and the consistency of this phenomenon. In particular, the absence of ghosts, already at the linear level, implies that in any such theory the graviton should either have a mass 1/L, or be a resonance of similar width. This has profound physical implications for the degravitation idea.
29630378
Cosmological classicalization: maintaining unitarity under relevant deformations of the Einstein-Hilbert action.
Generic relevant deformations of Einstein's gravity theory contain additional degrees of freedom that have a multifaceted stabilization dynamics on curved spacetimes. We show that these relevant degrees of freedom are self-protected against unitarity violations by the formation of classical field lumps that eventually merge to a new background geometry. The transition is heralded by the massive decay of the original vacuum and evolves through a strong coupling regime. This process fits in the recently proposed classicalization mechanism and extends it further to free field dynamics on curved backgrounds.
1452681
FORMATION OF SMALL-SCALE STRUCTURE IN SUSY CDM
The lightest supersymmetric particle, most likely the lightest neutralino, is one of the most prominent particle candidates for cold dark matter (CDM). We show that the primordial spectrum of density fluctuations in neutralino CDM has a sharp cut-off, induced by two different damping mechanisms. During the kinetic decoupling of neutralinos, non-equilibrium processes constitute viscosity effects, which damp or even absorb density perturbations in CDM. After the last scattering of neutralinos, free streaming induces neutralino flows from overdense to underdense regions of space. Both damping mechanisms together define a minimal mass scale for perturbations in neutralino CDM, before the inhomogeneities enter the nonlinear epoch of structure formation. We find that the very first gravitationally bound neutralino clouds ought to have masses above 10 −6 M⊙, which is six orders of magnitude above the mass of possible axion miniclusters.
37255447
A Quantum Bound-State Description of Black Holes
A relativistic framework for the description of bound states consisting of a large number of quantum constituents is presented, and applied to black-hole interiors. At the parton level, the constituent distribution, number and energy density inside black holes are calculated, and gauge corrections are discussed. A simple scaling relation between the black hole mass and constituent number is established.
120335892
Study of SHE at the GSI-SHIP
Abstract An overview of present experimental investigation of superheavy elements is given. Using cold fusion reactions which are based on lead and bismuth targets, relatively neutron deficient isotopes of the elements from 107 to 113 were synthesized at GSI in Darmstadt, Germany, and/or at RIKEN in Wako, Japan. In hot fusion reactions of 48 Ca projectiles with actinide targets more neutron rich isotopes of the elements from 112 to 116 and even 118 were produced at FLNR in Dubna, Russia. Recently, part of these data, which represent the first identification of nuclei located on the predicted island of SHEs, were confirmed in two independent experiments. The data are compared with theoretical descriptions.
117172489
alpha decay of At-194
Detailed {alpha}-decay studies of the neutron-deficient isotope {sup 194}At have been performed in the complete fusion reaction {sup 56}Fe+{sup 141}Pr{yields}{sup 194}At+3n at the velocity filter SHIP. Two {alpha}-decaying isomeric states with half-lives of T{sub 1/2}({sup 194}At{sup m1})=310(8) ms and T{sub 1/2}({sup 194}At{sup m2})=253(10) ms were identified in this nucleus. Their complex decays to the states in the daughter nucleus {sup 190}Bi are discussed in the article. We propose that similar to the case of the neighboring {sup 191,192,193,195}At isotopes, the oblate-deformed configurations based on the proton 1/2{sup +}[440] and/or 7/2{sup -}[514] Nilsson orbitals become important in {sup 194}At. A new isomeric state with the half-life of 175(8) ns was observed in {sup 190}Bi.
123438213
Large size foil-microchannel plate timing detectors
Abstract A large area foil-microchannel plate time-of-flight (TOF) system is presented. The parameters of the system are as follows: 55 cm 2 active area, 99.8% detection efficiency, 100% transparency and 700 ps time resolution. The TOF system, unique in size and conditions of exploitation, consists of two (or three) detectors used also as anticoincidence units for the analysing multistrip Si-detector array.
120695709
Strong influence of the entrance channel on the formation of compound nuclei Th216,222* and their evaporation residues
The dynamical effects of the entrance channel on the formation of the evaporation residues are studied by analyzing the $^{40}\mathrm{Ar}+^{176}\mathrm{Hf}$, $^{86}\mathrm{Kr}+^{130,136}\mathrm{Xe}$, $^{124}\mathrm{Sn}+^{92}\mathrm{Zr}$, and $^{48}\mathrm{Ca}+^{174}\mathrm{Yb}$ reactions leading to the $^{216}\mathrm{Th}{}^{*}$ and $^{222}\mathrm{Th}{}^{*}$ compound nuclei. We find that the difference between the evaporation residue cross sections for the reactions leading to the same compound nucleus is caused by the different angular momentum distributions of the partial fusion cross sections ${\ensuremath{\sigma}}_{\mathrm{fus}}^{\ensuremath{\ell}}({E}_{c.m.})$. The strong dependence of the fusion angular momentum distribution on the mass (charge) asymmetry and shell structure of reactants is demonstrated. The effect of the $A/Z$ ratio for the $^{86}\mathrm{Kr}+^{130,136}\mathrm{Xe}$ reactions is discussed. The dynamical conditions of capture affect the competition between complete fusion and quasifission and, consequently, the shape of the angular momentum distribution of the compound nucleus. By this way the peculiarities of the entrance channel also affect the fission-evaporation competition of the excited intermediate nuclei along the deexcitation cascade of the compound nucleus and, consequently, the evaporation residue formation.
124799624
Fusion probabilities in the reactions 40, Ca-48 + U-238 at energies around the Coulomb barrier