A Kaluza-Klein model, with a matter source associated with Hawking radiation from an evaporating black hole, is used to obtain a simple form for the radion effective potential. The environmental effect generally causes a matter-induced shift of the radion vacuum, resulting in the formation of a radion cloud around the hole. There is an albedo due to the radion cloud, with an energy-dependent reflection coefficient that depends upon the size of the extra dimensions and the temperature of the hole.

We study the Aharony-Bergman-Jafferis-Maldacena (ABJM) theory without and with mass deformation. It is shown that maximally supersymmetry preserving, D-term, and F-term mass deformations of single mass parameter are equivalent. We obtain vortex-type half-BPS equations and the corresponding energy bound. For the undeformed ABJM theory, the resulting half-BPS equation is the same as that in supersymmetric Yang-Mills theory and no finite energy regular BPS solution is found. For the mass-deformed ABJM theory, the half-BPS equations for $\mathrm{U}(2)\times \mathrm{U}(2)$ case reduce to the vortex equation in Maxwell-Higgs theory, which supports static regular multivortex solutions. In $\mathrm{U}(N)\times \mathrm{U}(N)$ case with $N>2$ the non-Abelian vortex equation of Yang-Mills-Higgs theory is obtained.

Using dimensional regularization, we compute the one-loop quantum and thermal corrections to the profile of the bosonic ($1+1$)-dimensional ${\phi }^4$ kink, the sine-Gordon kink, and the $C{P}^1$ kink, and higher-dimensional ${\phi }^4$ kink domain walls. Starting from the Heisenberg field equation in the presence of the nontrivial kink background we derive analytically results for the temperature-dependent mean field which display the onset of the melting of kinks as the system is heated towards a symmetry-restoring phase transition. The result is shown to simplify significantly when expressed in terms of a self-consistently defined thermal screening mass. In the case of domain walls, we find infrared singularities in the kink profile, which corresponds to interface roughening depending on the system size. Finally we calculate the energy density profile of ${\phi }^4$ kink domain walls and find that in contrast to the total surface tension the local distribution requires composite operator renormalization in $3+1$ dimensions.

In heavy-ion collisions the created quark-gluon plasma forms a quickly evolving background, leading to a time dependent radiative behavior of high momentum partons traversing the medium. We use the Schwinger-Keldysh formalism to describe the jet evolution as a nonequilibrium process including the Landau-Pomeranschuk-Migdal effect. Concentrating on photon emission, a comparison of our results to a quasistatic calculation shows good agreement, leading to the conclusion that the radiative behavior follows the changes in the medium almost instantaneously.

We compute the flux of linear momentum carried by gravitational waves emitted from spinning binary black holes at second post-Newtonian (2PN) order for generic orbits. In particular we provide explicit expressions of three new types of terms, namely, next-to-leading order spin-orbit terms at 1.5 post-Newtonian (1.5PN) order, spin-orbit tail terms at 2PN order, and spin-spin terms at 2PN order. Restricting ourselves to quasicircular orbits, we integrate the linear-momentum flux over time to obtain the recoil velocity as function of orbital frequency. We find that in the so-called superkick configuration the higher-order spin corrections can increase the recoil velocity up to a factor $\sim 3$ with respect to the leading-order PN prediction. Whereas the recoil velocity computed in PN theory within the adiabatic approximation can accurately describe the early inspiral phase, we find that its fast increase during the late inspiral and plunge, and the arbitrariness in determining until when it should be trusted, makes the PN predictions for the total recoil not very accurate and robust. Nevertheless, the linear-momentum flux at higher PN orders can be employed to build more reliable resummed expressions aimed at capturing the nonperturbative effects until merger. Furthermore, we provide expressions valid for generic orbits, and accurate at 2PN order, for the energy and angular momentum carried by gravitational waves emitted from spinning binary black holes. Specializing to quasicircular orbits we compute the spin-spin terms at 2PN order in the expression for the evolution of the orbital frequency and found agreement with Mikóczi, Vasúth, and Gergely. We also verified that in the limit of extreme mass ratio our expressions for the energy and angular momentum fluxes match the ones of Tagoshi, Shibata, Tanaka, and Sasaki obtained in the context of black hole perturbation theory.

We consider Brans-Dicke (BD) scalar tensor theory in the conformally transformed Einstein frame. In this frame BD theory behaves like an interacting quintessence model. We find the necessary conditions on the form of the potential $V(\phi )$ in order to have thawing behavior. Finally, by setting the BD coupling constant $\omega =0$, the metric $f(R)$ gravity has been considered in the Einstein frame. Assuming the existence of thawing solution, some necessary conditions for $f(R)$ gravity models have been derived.

The Casher argument, which is believed to be quite general, states that in the confining regime chiral symmetry is necessarily broken. In the large-$N_c$ limit and at moderate and low temperatures, QCD is confining up to arbitrary large densities, and there should appear a quarkyonic matter. It has been demonstrated, within a manifestly confining and chirally symmetric model, which is a $3+1$ dimensional generalization of the ’t Hooft model, that, at zero temperature and at a density exceeding a critical one, the chiral symmetry is restored while quarks remain confined in color-singlet hadrons. This is in conflict with the Casher argument. Here, we explain the reason why the Casher argument fails and clarify the physical mechanism lying behind such confined but chirally symmetric hadrons.

We compute the radial distributions of the vector and axial charge density as well as of the matter density in the heavy-light mesons on the lattice. The results for the lowest lying static heavy-light mesons and their first excited counterparts are obtained with $N_f=2$ dynamical quarks of Wilson (clover) type and with the various improved static heavy-quark actions. From these distributions we were able to compute the corresponding charges and slopes of the form factors (i.e. $⟨r^2⟩$). Those results are presented, and briefly discussed too.

We study the response of the QCD vacuum to an external Abelian chromomagnetic field in the framework of a nonlocal Nambu–Jona-Lasinio model with the Polyakov loop. We use the lattice results on the deconfinement temperature of the pure gauge theory to compute the same quantity in the presence of dynamical quarks. We find a linear relationship between the deconfinement temperature with quarks and the squared root of the applied field strength, $gH$, in qualitative (and to some extent also quantitative) agreement with existing lattice calculations. On the other hand, we find a discrepancy on the approximate chiral symmetry restoration: while lattice results suggest the deconfinement and the chiral restoration remain linked even at a nonzero value of $gH$, our results are consistent with a scenario in which the two transitions are separated as $gH$ is increased.

We study the $T$ odd correlations induced by $CP$ violating anomalous top-quark couplings at both production and decay level in the process $gg\to t\overline{t}\to (b{\mu }^{+}{\nu }_{\mu })(\overline{b}{\mu }^{-}{\overline{\nu }}_{\mu })$. We consider several counting asymmetries at the parton level and find the ones with the most sensitivity to each of these anomalous couplings at the LHC.

We consider formation of composite strings and domain walls as a result of fusion of two elementary objects (elementary strings in the first case and elementary walls in the second) located at a distance from each other. The tension of the composite object $T_2$ is assumed to be less than twice the tension of the elementary object $T_1$, so that bound states are possible. If in the initial state the distance $d$ between the fusing strings or walls is much larger than their thickness and satisfies the conditions $T_1{d}^2\gg 1$ (in the string case) and $T_1{d}^3\gg 1$ (in the wall case), the problem can be fully solved quasiclassically. The fusion probability is determined by the first, “under the barrier” stage of the process. We find the bounce configuration and its extremal action $S_B$. In the wall problem $e^{-S_B}$ gives the fusion probability per unit time per unit area. In the string case, due to a logarithmic infrared divergence, the problem is well formulated only for finite-length strings. The fusion probability per unit time can be found in the limit in which the string length is much larger than the distance between two merging strings.

Local non-Hermitian potentials $V(x)\ne V^{*}(x)$ can, sometimes, generate stable bound states $\psi (x)$ at real energies. Unfortunately, the idea [based on the use of a non-Dirac ad hoc metric $\Theta (x,x^{\prime })\ne \delta (x-x^{\prime })$ in Hilbert space] cannot directly be transferred to scattering due to the related loss of the asymptotic observability of $x$ [cf. H. F. Jones, Phys. Rev. D 78, 065032 (2008)]. We argue that for smeared (typically, nonlocal or momentum-dependent) potentials $V\ne V^{†}$ this difficulty may be circumvented. A return to the usual (i.e., causal and unitary) quantum scattering scenario is then illustrated via an exactly solvable multiple-scattering example. In it, the anomalous loss of observability of the coordinate remains restricted to a small vicinity of the scattering centers.

Much attention has been recently devoted to the possibility that quantum gravity effects could lead to departures from special relativity in the form of a deformed Poincarè algebra. These proposals go generically under the name of doubly or deformed special relativity (DSR). In this article we further explore a recently proposed class of quantum field theories, involving noncanonically commuting complex scalar fields, which have been shown to entail a DSR-like symmetry. An open issue for such theories is whether the DSR-like symmetry has to be taken as a physically relevant symmetry, or if in fact the “true” symmetries of the theory are just rotations and translations while boost invariance has to be considered broken. Here we analyze this issue by extending the known results to curved spacetime under both of the previous assumptions. We show that if the symmetry of the free theory is taken to be a DSR-like realization of the Poincaré symmetry, then it is not possible to render such a symmetry a gauge symmetry of the curved physical spacetime. However, it is possible to introduce an auxiliary spacetime which allows one to describe the theory as a standard quantum field theory in curved spacetime. Alternatively, taking the point of view that the noncanonical commutation of the fields actually implies a breakdown of boost invariance, the physical spacetime manifold has to be foliated in surfaces of simultaneity, and the field theory can be coupled to gravity by making use of the Arnowitt-Deser-Misner prescription.

Gravitational waves propagate along null geodesics like light rays in the geometrical optics approximation, and they may have a chance to suffer from gravitational lensing by intervening objects, as is the case for electromagnetic waves. Long wavelengths of gravitational waves and compactness of possible sources may enable us to extract information in the interference among the lensed images. We point out that the interference term contains information of relative transverse velocity of the source-lens-observer system, which may be obtained by possible future space-borne gravitational wave detectors such as BBO/DECIGO.

Contrary to a common argument that a small increase in the strength of the strong force would lead to destruction of all hydrogen in the big bang due to binding of the diproton and the dineutron with a catastrophic impact on life as we know it, we show that provided the increase in strong force coupling constant is less than about 50% substantial amounts of hydrogen remain. The reason is that an increase in strong force strength leads to tighter binding of the deuteron, permitting nucleosynthesis to occur earlier in the big bang at higher temperature than in the standard big bang. Photodestruction of the less tightly bound diproton and dineutron delays their production to after the bulk of nucleosynthesis is complete. The decay of the diproton can, however, lead to relatively large abundances of deuterium.

We construct nontopological solitonic solutions in ($3+1$)-dimensional Minkowski spacetime carrying a conserved global $U(1)$ charge and nonvanishing angular momentum in a supersymmetric extension of the standard model with low-energy, gauge-mediated symmetry breaking.

Leptogenic supersymmetry is a scenario characterized by cascade decays with copious lepton production. Leptogenic models have striking signatures that can be probed by the LHC even in the 10 TeV run with as little as $200{\mathrm{pb}}^{-1}$ of data, provided the squark masses are about 1 TeV. Leptogenic supersymmetry spectrum arises in several well-motivated models and its signatures are long-lived sleptons, numerous isolated leptons, abundant Higgs production, rather energetic jets, and no missing energy. The Higgs can be discovered in the $h\to b\overline{b}$ mode via the $4\mathrm{\text{leptons}}+4\mathrm{\text{jets}}$ channel because the leptons accompanying Higgs production suppress the background. The superparticle masses in leptogenic supersymmetry can be measured efficiently due to lack of missing energy and high lepton multiplicity. We estimate that $1{\mathrm{fb}}^{-1}$ of integrated luminosity is sufficient to determine the light Higgs, neutralinos, charginos, slepton, sneutrino, and squark masses in a 14 TeV run.

We propose and study a constrained version of the exceptional supersymmetric standard model (${\mathrm{E}}_6\mathrm{SSM}$), which we call the ${\mathrm{cE}}_6\mathrm{SSM}$, based on a universal high energy scalar mass $m_0$, trilinear scalar coupling $A_0$ and gaugino mass $M_{1/2}$. We derive the renormalization group (RG) Equations for the ${\mathrm{cE}}_6\mathrm{SSM}$, including the extra $U(1{)}_N$ gauge factor and the low-energy matter content involving three 27 representations of ${\mathrm{E}}_6$. We perform a numerical RG analysis for the ${\mathrm{cE}}_6\mathrm{SSM}$, imposing the usual low-energy experimental constraints and successful electroweak symmetry breaking. Our analysis reveals that the sparticle spectrum of the ${\mathrm{cE}}_6\mathrm{SSM}$ involves a light gluino, two light neutralinos, and a light chargino. Furthermore, although the squarks, sleptons, and $Z^{\prime }$ boson are typically heavy, the exotic quarks and squarks can also be relatively light. We finally specify a set of benchmark points, which correspond to particle spectra, production modes, and decay patterns peculiar to the ${\mathrm{cE}}_6\mathrm{SSM}$, altogether leading to spectacular new physics signals at the Large Hadron Collider.

We propose a model in which supersymmetric weak scale dark matter is charged under a $U(1{)}_d$ dark gauge symmetry. Kinetic mixing between $U(1{)}_d$ and hypercharge generates the appropriate hierarchy of scales needed to explain PAMELA and ATIC with a GeV scale force carrier and DAMA (or INTEGRAL) using the proposals of inelastic (or, respectively, exciting) dark matter. Because of the extreme simplicity of this setup, observational constraints lead to unambiguous determination of the model parameters. In particular, the DAMA scattering cross section is directly related to the size of the hypercharge D-term vacuum expectation value. The known relic abundance of dark matter can be used to fix the ratio of the dark sector coupling to the dark matter mass. Finally, the recent observation of cosmic ray positron and electron excesses can be used to fix the mass of the dark matter through the observation of a shoulder in the spectrum and the size of the kinetic mixing by fitting to the rate. These parameters can be used to make further predictions, which can be checked at future direct detection, indirect detection, as well as collider experiments.

We investigate the spectroscopy and decays of the charm-strange quarkonium system in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections, and the complete perturbative one-loop quantum chromodynamic short distance potential. The unperturbed wave functions of the various states are obtained using a variational technique. These are then used in a perturbative treatment of the potential to fit the mass spectrum of the $c\overline{s}$ system and calculate the radiative decay widths. Our results compare well with the available data for the spectrum of $D_s$ states. We include a discussion of the effect of mixing and investigation of the Lorentz nature of the confining potential.