Baryogenesis from the amplification of vacuum fluctuations during inflation

We propose that the baryon asymmetry of the Universe may originate from the amplification of quantum fluctuations of a light complex scalar field during inflation. CP-violation is sourced by complex mass terms, which are smaller than the Hubble rate, as well as non-standard kinetic terms. We find that, when assuming 60 e-folds of inflation, an asymmetry in accordance with observation can result for models where the energy scale of inflation is of the order of 10^16 GeV. Lower scales may be achieved when assuming substantially larger amounts of e-folds.Comment: 18 page

De Sitter Breaking through Infrared Divergences

Just because the propagator of some field obeys a de Sitter invariant equation does not mean it possesses a de Sitter invariant solution. The classic example is the propagator of a massless, minimally coupled scalar. We show that the same thing happens for massive scalars with $M_S^2 < 0$, and for massive transverse vectors with $M_V^2 \leq -2 (D-1) H^2$, where $D$ is the dimension of spacetime and $H$ is the Hubble parameter. Although all masses in these ranges give infrared divergent mode sums, using dimensional regularization (or any other analytic continuation technique) to define the mode sums leads to the incorrect conclusion that de Sitter invariant solutions exist except at discrete values of the masses.Comment: 27 pages, no figures, uses LaTeX 2epsilo

A prototype for dS/CFT

We consider dS_2/CFT_1 where the asymptotic symmetry group of the de Sitter spacetime contains the Virasoro algebra. We construct representations of the Virasoro algebra realized in the Fock space of a massive scalar field in de Sitter, built as excitations of the Euclidean vacuum state. These representations are unitary, without highest weight, and have vanishing central charge. They provide a prototype for a new class of conformal field theories dual to de Sitter backgrounds in string theory. The mapping of operators in the CFT to bulk quantities is described in detail. We comment on the extension to dS_3/CFT_2.Comment: 17 pages, revtex

Bounds on the nonminimal coupling of the Higgs Boson to gravity

We derive the first bound on the value of the Higgs boson nonminimal coupling to the Ricci scalar. We show that the recent discovery of the Higgs boson at the Large Hadron Collider at CERN implies that the nonminimal coupling is smaller than 2.6×10^15

Effect of gold and nickel co-additives on gas-sensitive characteristics of SnO2 thin-film on exposure to hydrogen and nitrogen dioxide

The results of investigation of the gas-sensitive properties of sensors based on the tin dioxide thin films with combined additives of gold and nickel obtained by the DC - magnetron sputtering are presented. The investigated sensors are characterized by a high response to low concentrations of NO2 of 0.45 – 10.23 ppm at temperatures of 50 – 150 °C with response time of 10 s. The sensitivity of sensors to hydrogen appears at the temperature of 250 °C. The hydrogen sensors are characterized by high reproducibility of the measurement results. The obtained results are explained by the synergistic effect of gold and nickel additives, as well as the ability of the Ni to prevent the interaction of hydrogen with lattice oxygen atoms in the subsurface part of tin dioxide

Inflaton Decay in an Alpha Vacuum

We study the alpha vacua of de Sitter space by considering the decay rate of the inflaton field coupled to a scalar field placed in an alpha vacuum. We find an {\em alpha dependent} Bose enhancement relative to the Bunch-Davies vacuum and, surprisingly, no non-renormalizable divergences. We also consider a modified alpha dependent time ordering prescription for the Feynman propagator and show that it leads to an alpha independent result. This result suggests that it may be possible to calculate in any alpha vacuum if we employ the appropriate causality preserving prescription.Comment: 16 pages, 1 figure, Revtex 4 preprin

Vacuum energy induced by an impenetrable flux tube of finite radius

We consider the effect of the magnetic field background in the form of a tube of the finite transverse size on the vacuum of the quantized charged massive scalar field which is subject to the Dirichlet boundary condition at the edge of the tube. The vacuum energy is induced, being periodic in the value of the magnetic flux enclosed in the tube. Our previous study in J. Phys. A: Vol.43, 175401 (2010) is extended to the case of smaller radius of the tube and larger distances from it. The dependence of the vacuum energy density on the distance from the tube and on the coupling to the space-time curvature scalar is comprehensively analyzed.Comment: 11 pages, 8 figures, journal version, abstract extended. arXiv admin note: substantial text overlap with arXiv:0911.287

Transforming to Lorentz Gauge on de Sitter

We demonstrate that certain gauge fixing functionals cannot be added to the action on backgrounds such as de Sitter in which a linearization instability is present. We also construct the field dependent gauge transformation which carries the electromagnetic vector potential from a convenient, non-de Sitter invariant gauge to the de Sitter invariant, Lorentz gauge. The transformed propagator agrees with the de Sitter invariant result previously found by solving the propagator equation in Lorentz gauge. This shows that the gauge transformation technique will eliminate unphysical breaking of de Sitter invariance introduced by a gauge condition. It is suggested that the same technique can be used to finally resolve the issue of whether or not free gravitons are de Sitter invariant.Comment: 45 page

Extended Quintessence with non-minimally coupled phantom scalar field

We investigate evolutional paths of an extended quintessence with a non-minimally coupled phantom scalar field $\psi$ to the Ricci curvature. The dynamical system methods are used to investigate typical regimes of dynamics at the late time. We demonstrate that there are two generic types of evolutional scenarios which approach the attractor (a focus or a node type critical point) in the phase space: the quasi-oscillatory and monotonic trajectories approach to the attractor which represents the FRW model with the cosmological constant. We demonstrate that dynamical system admits invariant two-dimensional submanifold and discussion that which cosmological scenario is realized depends on behavior of the system on the phase plane $(\psi, \psi')$. We formulate simple conditions on the value of coupling constant $\xi$ for which trajectories tend to the focus in the phase plane and hence damping oscillations around the mysterious value $w=-1$. We describe this condition in terms of slow-roll parameters calculated at the critical point. We discover that the generic trajectories in the focus-attractor scenario come from the unstable node. It is also investigated the exact form of the parametrization of the equation of state parameter $w(z)$ (directly determined from dynamics) which assumes a different form for both scenarios.Comment: revtex4, 15 pages, 9 figures; (v2) published versio

Localized Particle States and Dynamics Gravitational Effects

Scalar particles--i.e., scalar-field excitations--in de Sitter space exhibit behavior unlike either classical particles in expanding space or quantum particles in flat spacetime. Their energies oscillate forever, and their interactions are spread out in energy. Here it is shown that these features characterize not only normal-mode excitations spread out over all space, but localized particles or wave packets as well. Both one-particle and coherent states of a massive, minimally coupled scalar field in de Sitter space, associated with classical wave packets, are constructed explicitly. Their energy expectation values and corresponding Unruh-DeWitt detector response functions are calculated. Numerical evaluation of these quantities for a simple set of classical wave packets clearly displays these novel features. Hence, given the observed accelerating expansion of the Universe, it is possible that observation of an ultralow-mass scalar particle could yield direct confirmation of distinct predictions of quantum field theory in curved spacetime.Comment: 12 pages, 5 figure