We consider a smooth hybrid inflation scenario based on a supersymmetric $SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}$ model. The Higgs triplets involved in the model play a key role in inflation as well as in explaining the observed baryon asymmetry of the Universe. We show that the baryon asymmetry can originate via nonthermal triplet leptogenesis from the decay of $SU(2{)}_L$ triplets, whose tiny vacuum expectation values also provide masses for the light neutrinos.

Despite the ubiquity of thunderstorms, lightning, and related electrical phenomena, many important electromagnetic processes in our atmosphere are poorly understood; the key questions about the thundercloud electrification and lightning initiation remain unanswered. The bulk information on particle fluxes correlated with thunderstorm can be used to better understand the electrical structure of thunderclouds. Only very specific electric configuration of the lower part of the cloud can support the sustainable acceleration of the electrons. Our analysis is based on the thunderstorm data from the Aragats Mountain in Armenia, 3200 m above sea level Varieties of particle detectors located at Aragats Space Environmental Center are registering neutral and charged particle fluxes correlated with thunderstorms, so-called Thunderstorm Ground Enhancements (TGEs). Simultaneously the electrical mills and lightning detectors are monitoring the near-surface electric field and type of lightning occurrences; weather stations are measuring plenty of meteorological parameters. In the present paper we relate particle fluxes to the electrical structure of thunderclouds, namely, to the origination of the Lower Positive Charged Region (LPCR) below the main negative charged layer in the middle of the thundercloud, and to lightning occurrences. Only after creation of the lower dipole in the thundercloud can the electrons be accelerated and particle flux be directed downward. Maturity of the LPCR is correlated with increasing particle fluxes. Thus, the temporal evolution of TGE gives direct evidence of the maturity of LPCR, its initiation, and its decaying.

We present a comprehensive analysis of the light condensates in QCD with $1+1+1$ sea quark flavors (with mass-degenerate light quarks of different electric charges) at zero and nonzero temperatures of up to 190 MeV and external magnetic fields $B<1{\mathrm{GeV}}^2/e$. We employ stout smeared staggered fermions with physical quark masses and extrapolate the results to the continuum limit. At low temperatures we confirm the magnetic catalysis scenario predicted by many model calculations while around the crossover the condensate develops a complex dependence on the external magnetic field, resulting in a decrease of the transition temperature.

A sample of $114\pm 11$ $B_s^0\to J/\psi K^{-}{\pi }^{+}$ signal events obtained with $0.37{\mathrm{fb}}^{-1}$ of $pp$ collisions at $\sqrt{s}=7\mathrm{TeV}$ collected by the LHCb experiment is used to measure the branching fraction and polarization amplitudes of the $B_s^0\to J/\psi {\overline{K}}^{*0}$ decay, with ${\overline{K}}^{*0}\to K^{-}{\pi }^{+}$. The $K^{-}{\pi }^{+}$ mass spectrum of the candidates in the $B_s^0$ peak is dominated by the ${\overline{K}}^{*0}$ contribution. Subtracting the nonresonant $K^{-}{\pi }^{+}$ component, the branching fraction of $B_s^0\to J/\psi {\overline{K}}^{*0}$ is $({4.4}_{-0.4}^{+0.5}\pm 0.8)\times {10}^{-5}$, where the first uncertainty is statistical and the second is systematic. A fit to the angular distribution of the decay products yields the $K^{*0}$ polarization fractions $f_L=0.50\pm 0.08\pm 0.02$ and $f_{\parallel }={0.19}_{-0.08}^{+0.10}\pm 0.02$.

We revisit, starting from the first principles, the calculation of scattering cross sections in theories with violation of the Lorentz invariance. Our approach takes into account all information about the Lagrangian of the theory and is applicable to the case of Lorentz violation by higher-dimension operators. As an illustration, we consider spinor electrodynamics with Lorentz violating operators of dimension four and six that preserve $CPT$, parity, and rotational invariance in a preferred frame. We derive the Feynman rules and formulas for the sums over polarizations in this model and use them to compute the probabilities of several astrophysically relevant processes. We calculate the rates of photon decay and vacuum Cherenkov radiation along with the cross sections of electron-positron pair production on background radiation and in the Coulomb field. The latter process is essential for detection of photon-induced air showers in the atmosphere.

In numerical simulations of black hole binaries, Pretorius and Khurana [Classical Quantum Gravity 24, S83 (2007)] have observed critical behavior at the threshold between scattering and immediate merger. The number of orbits scales as $n\simeq -\gamma \ln |p-p_{*}|$ along any one-parameter family of initial data such that the threshold is at $p=p_{*}$. Hence, they conjecture that in ultrarelativistic collisions almost all the kinetic energy can be converted into gravitational waves if the impact parameter is fine-tuned to the threshold. As a toy model for the binary, they consider the geodesic motion of a test particle in a Kerr black hole spacetime, where the unstable circular geodesics play the role of critical solutions, and calculate the critical exponent $\gamma$. Here, we incorporate radiation reaction into this model using the self-force approximation. The critical solution now evolves adiabatically along a sequence of unstable circular geodesic orbits under the effect of the self-force. We confirm that almost all the initial energy and angular momentum are radiated on the critical solution. Our calculation suggests that, even for infinite initial energy, this happens over a finite number of orbits given by $n_{\infty }\simeq 0.41/\eta$, where $\eta$ is the (small) mass ratio. We derive expressions for the time spent on the critical solution, number of orbits and radiated energy as functions of the initial energy and impact parameter.

We study the interaction between two parallel cosmic strings induced by gauge fields and by scalar fields with nonminimal couplings to curvature. For small deficit angles the gauge field behaves like a collection of nonminimal scalars with a specific value for the nonminimal coupling. We check this equivalence by computing the interaction energy between strings at first order in the deficit angles. This result provides another physical context for the “contact terms” which play an important role in the renormalization of black hole entropy due to a spin-1 field.

We discuss the compatibility between the quark-shell picture and the meson-nucleon scattering picture in large $N_c$ QCD for mixed symmetric $\ell =1$ states previously analyzed by using a simple Hamiltonian including operators up to order $\mathcal{O}(N_c^0)$ defined in the standard ground state $\mathrm{\text{symmetric core}}+\mathrm{\text{excited quark}}$ procedure. Here we introduce a Hamiltonian of order $\mathcal{O}(N_c^0)$ defined in a new approach where the separation of the system into two parts is not required. Three degenerate sets of states (towers) with the same quantum numbers as in the scattering picture and in the standard procedure are obtained. Thus the compatibility is equally achieved. The eigenvalues of the presently chosen Hamiltonian also have simple analytic expressions, depending linearly on the three dynamical coefficients entering the Hamiltonian. This reinforces the validity of the new approach which had already successfully described excited negative parity baryons in a large energy range.

We formulate the necessary conditions for a scalar potential to exhibit spontaneous $CP$ violation. Associated with each complex scalar field is a U(1) symmetry that may be explicitly broken by terms in the scalar potential (called spurions). In order for $CP$-odd phases in the vacuum to be physical, these phases must be related to spontaneously broken U(1) generators that are also explicitly broken by a sufficient number of inequivalent spurions. In the case where the vacuum is characterized by a single complex phase, our result implies that the phase must be associated with a U(1) generator that is broken explicitly by at least two inequivalent spurions. A suitable generalization of this result to the case of multiple complex phases has also been obtained. These conditions may be used both to distinguish models capable of spontaneous $CP$ violation and as a model building technique for obtaining spontaneously $CP$-violating deformations of $CP$-conserving models. As an example, we analyze the generic two Higgs doublet model, where we also carry out a complete spurion analysis. We also comment on other models with spontaneous $CP$ violation, including the chiral Lagrangian, a minimal version of the Nelson-Barr model, and little Higgs models with spontaneous $CP$ violation.

Slowly walking technicolor models provide a mechanism for electroweak symmetry breaking whose nonperturbative lattice investigation is rather challenging. Here we demonstrate walking near a conformal fixed point considering the 2-d lattice $O(3)$ model at vacuum angle $\theta \approx \pi$. The essential features of walking technicolor models are shared by this toy model and can be accurately investigated by numerical simulations. We show results for the running coupling and the $\beta$-function, and we perform a finite-size scaling analysis of the mass gap close to the conformal point.

The recent observation of the smallest neutrino mixing angle ${\theta }_{13}$ in the Daya Bay and RENO experiments motivates us to examine whether ${\theta }_{13}\simeq 9°$ at the electroweak scale can be generated from ${\theta }_{13}=0°$ at a superhigh-energy scale via the radiative corrections. We find that it is difficult but not impossible in the minimal supersymmetric standard model, and a relatively large ${\theta }_{13}$ may have some nontrivial impacts on the running behaviors of the other two mixing angles and $CP$-violating phases. In particular, we demonstrate that the $CP$-violating phases play a crucial role in the evolution of the mixing angles by using the one-loop renormalization-group equations of the Dirac or Majorana neutrinos in the minimal supersymmetric standard model. We also take the correlative neutrino mixing pattern with ${\theta }_{12}\simeq 35.3°$, ${\theta }_{23}=45°$, and ${\theta }_{13}\simeq 9.7°$ at a presumable flavor symmetry scale as an example to illustrate that the three mixing angles can receive comparably small radiative corrections and thus evolve to their best-fit values at the electroweak scale if the $CP$-violating phases are properly adjusted.

The properties of two-flavored massive Nambu–Jona-Lasinio model in ($1+1$)-dimensional spacetime are investigated in the presence of isospin and quark number chemical potentials. The consideration is performed in the large-$N_c$ limit, where $N_c$ is the number of colored quarks. It is shown in the framework of this model that charged pion condensation phenomenon of dense quark/hadron isotopically asymmetric matter is rather a spatially inhomogeneous than a homogeneous one.

We investigate the suitability and properties of a quasi-Kinnersley tetrad and a geometrically motivated coordinate system as tools for quantifying both strong-field and wave-zone effects in numerical relativity (NR) simulations. We fix two of the coordinate degrees of freedom of the metric, namely, the radial and latitudinal coordinates, using the Coulomb potential associated with the quasi-Kinnersley transverse frame. These coordinates are invariants of the spacetime and can be used to unambiguously fix the outstanding spin-boost freedom associated with the quasi-Kinnersley frame (and thus can be used to choose a preferred quasi-Kinnersley tetrad). In the limit of small perturbations about a Kerr spacetime, these geometrically motivated coordinates and quasi-Kinnersley tetrad reduce to Boyer-Lindquist coordinates and the Kinnersley tetrad, irrespective of the simulation gauge choice. We explore the properties of this construction both analytically and numerically, and we gain insights regarding the propagation of radiation described by a super-Poynting vector, further motivating the use of this construction in NR simulations. We also quantify in detail the peeling properties of the chosen tetrad and gauge. We argue that these choices are particularly well-suited for a rapidly converging wave-extraction algorithm as the extraction location approaches infinity, and we explore numerically the extent to which this property remains applicable on the interior of a computational domain. Using a number of additional tests, we verify numerically that the prescription behaves as required in the appropriate limits regardless of simulation gauge; these tests could also serve to benchmark other wave extraction methods. We explore the behavior of the geometrically motivated coordinate system in dynamical binary-black-hole NR mergers; while we obtain no unexpected results, we do find that these coordinates turn out to be useful for visualizing NR simulations (for example, for vividly illustrating effects such as the initial burst of spurious junk radiation passing through the computational domain). Finally, we carefully scrutinize the head-on collision of two black holes and, for example, the way in which the extracted waveform changes as it moves through the computational domain.

A small extended body moving through an external spacetime $g_{\alpha \beta }$ creates a metric perturbation $h_{\alpha \beta }$, which forces the body away from geodesic motion in $g_{\alpha \beta }$. The foundations of this effect, called the gravitational self-force, are now well established, but concrete results have mostly been limited to linear order. Accurately modeling the dynamics of compact binaries requires proceeding to nonlinear orders. To that end, I show how to obtain the metric perturbation outside the body at all orders in a class of generalized wave gauges. In a small buffer region surrounding the body, the form of the perturbation can be found analytically as an expansion for small distances $r$ from a representative worldline. Given only a specification of the body’s multipole moments, the field obtained in the buffer region suffices to find the metric everywhere outside the body via a numerical puncture scheme. Following this procedure at first and second order, I calculate the field in the buffer region around an arbitrarily structured compact body at sufficiently high order in $r$ to numerically implement a second-order puncture scheme, including effects of the body’s spin. I also define $n$th-order (local) generalizations of the Detweiler-Whiting singular and regular fields and show that in a certain sense, the body can be viewed as a skeleton of multipole moments.

We present results concerning propagation of the Gaussian state across the cosmological quantum bounce. The reduced phase space quantization of loop quantum cosmology is applied to the Friedman-Robertson-Walker universe with a free massless scalar field. Evolution of quantum moments of the canonical variables is investigated. The covariance turns out to be a monotonic function so it may be used as an evolution parameter having quantum origin. We show that for the Gaussian state the Universe is least quantum at the bounce. We propose explanation of this counter-intuitive feature using the entropy of squeezing. The obtained time dependence of entropy is in agreement with qualitative predictions based on von Neumann entropy for mixed states. We show that, for the considered Gaussian state, semiclassicality is preserved across the bounce, so there is no cosmic forgetfulness.

The validity of modified Newtonian dynamics (MOND) and tensor vector scalar (TeVeS) models of modified gravity has been recently tested by using lensing techniques, with the conclusion that a nontrivial component in the form of dark matter is needed in order to match the observations. In this work, those analyses are extended by comparing lensing to stellar masses for a sample of nine strong gravitational lenses which probe galactic scales. The sample is extracted from a recent work which presents the mass profile out to a few effective radii, therefore reaching into regions which are dominated by dark matter in the standard (general relativity) scenario. A range of interpolating functions are explored to test the validity of MOND/TeVeS in these systems. Out of the nine systems, there are five robust candidates with a significant excess (higher than 50%) of lensing mass with respect to stellar mass, irrespective of the stellar initial mass function. One of these lenses (Q0957) is located at the center of a galactic cluster. This system might be accommodated in MOND/TeVeS via the addition of a hot component, like a 2 eV neutrino, which contributes over cluster scales. However, the other four robust candidates (LBQS1009, HE1104, B1600, HE2149) are located in field/group regions, so that a cold component (cold dark matter) would be required even within the MOND/TeVeS framework. Our results, therefore, do not support recent claims that these alternative scenarios to cold dark matter can survive astrophysical data.

We derive new bounds on decaying dark matter from the gamma ray measurements of (i) the isotropic residual (extragalactic) background by Fermi and (ii) the Fornax galaxy cluster by H.E.S.S. We find that those from (i) are among the most stringent constraints currently available, for a large range of dark matter masses and a variety of decay modes, excluding half-lives up to $\sim {10}^{26}$ to few ${10}^{27}\mathrm{seconds}$. In particular, they rule out the interpretation in terms of decaying dark matter of the $e^{\pm }$ spectral features in PAMELA, Fermi and H.E.S.S., unless very conservative choices are adopted. We also discuss future prospects for CTA bounds from Fornax which, contrary to the present H.E.S.S. constraints of (ii), may allow for an interesting improvement and may become better than those from the current or future extragalactic Fermi data.

Cosmological Birefringence, a rotation of the polarization plane of radiation coming to us from distant astrophysical sources, may reveal parity violation in either the electromagnetic or gravitational sectors of the fundamental interactions in nature. Until only recently this phenomenon could be probed with only radio observations or observations at UV wavelengths. Recently, there is a substantial effort to constrain such nonstandard models using observations of the rotation of the polarization plane of cosmic microwave background (CMB) radiation. This can be done via measurements of the $B$-modes of the CMB or by measuring its $TB$ and EB correlations which vanish in the standard model. In this paper we show that $EB$ correlations-based estimator is the best for upcoming polarization experiments. The $EB$-based estimator surpasses other estimators because it has the smallest noise and of all the estimators is least affected by systematics. Current polarimeters are optimized for the detection of $B$-mode polarization from either primordial gravitational waves or by large-scale structures via gravitational lensing. In the paper we also study the optimization of CMB experiments for the detection of cosmological birefringence, in the presence of instrumental systematics, which by themselves are capable of producing $EB$ correlations, potentially mimicking cosmological birefringence.

We study the condensation phenomenon for a system of charged bosons in the presence of an external magnetic field. We show that condensation happens for a definite critical temperature instead of through a diffuse phase transition. The essential ingredient, overlooked in previous analyses and accounted for in this work, is the treatment of the plasma screening effects by means of resummation. We compute the critical temperature, for the case in which the condensate is made of charged pions and for typical densities found in compact astrophysical objects, for small and large values of the magnetic field. We show that the magnetic field catalyzes the onset of condensation at very small and at large values of the magnetic field, and that for intermediate values the critical temperature for condensation is lower than for the zero magnetic field case.