We consider gauge/gravity duality with flavor for the finite-temperature field theory dual of the AdS-Schwarzschild black hole background with embedded D7-brane probes. In particular, we investigate spectral functions at finite baryon density in the black hole phase. We determine the resonance frequencies corresponding to meson-mass peaks as function of the quark mass over temperature ratio. We find that these frequencies have a minimum for a finite value of the quark mass. If the quotient of quark mass and temperature is increased further, the peaks move to larger frequencies. At the same time the peaks narrow, in agreement with the formation of nearly stable vector meson states which exactly reproduce the meson-mass spectrum found at zero temperature. We also calculate the diffusion coefficient, which has finite value for all quark mass to temperature ratios, and exhibits a first-order phase transition. Finally we consider an isospin chemical potential and find that the spectral functions display a resonance peak splitting, similar to the isospin meson-mass splitting observed in effective QCD models.

We discuss the quantization of a class of relativistic fluid models defined in terms of one real and two complex conjugate potentials with values on a Kähler manifold, and parametrized by the Kähler potential $K(z,\overline{z})$ and a real number $\lambda$. In the Hamiltonian formulation, the canonical conjugate momenta of the potentials are subjected to second-class constraints which allow us to apply the symplectic projector method in order to find the physical degrees of freedom and the physical Hamiltonian. We construct the quantum theory for that class of models by employing the canonical quantization methods. We also show that a semiclassical theory in which the Kähler and the complex potentials are not quantized has a highly degenerate vacuum. We define and compute the quantum topological number (quantum linking number) operator which has nonvanishing contributions from the Kähler and complex potentials only. Also, we show that the vacuum and the states formed by tensoring the number operators eigenstates have zero linking number, and show that linear combinations of the tensor product of number operators eigenstates which have the form of entangled states have nonzero linking number.

The neutrinos detected from the next galactic core-collapse supernova will contain valuable information on the internal dynamics of the explosion. One mechanism leading to a temporal evolution of the neutrino signal is the variation of the induced neutrino flavor mixing driven by changes in the density profile. With one and two-dimensional hydrodynamical simulations we identify the behavior and properties of prominent features of the explosion. Using these results we demonstrate the time variation of the neutrino crossing probabilities due to changes in the Mikheyev-Smirnov-Wolfenstein (MSW) neutrino transformations as the star explodes by using the $S$-matrix—Monte Carlo—approach to neutrino propagation. After adopting spectra for the neutrinos emitted from the proto-neutron star we calculate for a galactic supernova the evolution of the positron spectra within a water Cerenkov detector and find that this signal allows us to probe of a number of explosion features.

Perturbative estimates suggest that extended topological defects such as cosmic strings emit few particles, but numerical simulations of the fields from which they are constructed suggest the opposite. In this paper we study the decay of the two-dimensional prototype of strings, domain walls in a simple scalar theory, solving the underlying quantum field theory in the Hartree approximation. We conclude that including the quantum effects makes the picture clear: the defects do not directly transform into particles, but there is a nonperturbative channel to microscopic classical structures in the form of propagating waves and persistent localized oscillations, which operates over a huge separation of scales. When quantum effects are included, the microscopic classical structures can decay into particles.

We analyze a class of 5D models where a 3 brane is generated by a bulk scalar field nonminimally coupled to gravity. We show that perturbative stability of such branes is normally guaranteed although nonminimal couplings are not innocuous in general. After the physical states are identified, the linearized equations for the propagating modes are evaluated into a Schrödinger form. The spectrum contains a tower of spin 2 and spin 0 fields with continuous masses starting from zero ones. For regular geometries the scalar spectrum contains a massless state which is always non-normalizable. The propagating massive scalar states are repelled off the brane due to a centrifugal potential.

The intermediate and late-time behavior of a massive Dirac field in the background of static spherically symmetric dilaton black hole solutions is investigated. The intermediate asymptotic behavior of a massive Dirac field depends on the mass parameter as well as the wave number of the mode, while the late-time behavior has a power-law decay rate independent of both.

We consider the Klein-Gordon equation in generalized higher-dimensional Kerr-NUT-(A)dS spacetime without imposing any restrictions on the functional parameters characterizing the metric. We establish commutativity of the second-order operators constructed from the Killing tensors found in [J. High Energy Phys. 02 (2007) 004] and show that these operators, along with the first-order operators originating from the Killing vectors, form a complete set of commuting symmetry operators (i.e., integrals of motion) for the Klein-Gordon equation. Moreover, we demonstrate that the separated solutions of the Klein-Gordon equation obtained in [J. High Energy Phys. 02 (2007) 005] are joint eigenfunctions for all of these operators. We also present an explicit form of the zero mode for the Klein-Gordon equation with zero mass. In the semiclassical approximation we find that the separated solutions of the Hamilton-Jacobi equation for geodesic motion are also solutions for a set of Hamilton-Jacobi-type equations which correspond to the quadratic conserved quantities arising from the above Killing tensors.

While the outcome of gravitational collapse in classical general relativity is unquestionably a black hole, up to now no full and complete semiclassical description of black hole formation has been thoroughly investigated. Here we revisit the standard scenario for this process. By analyzing how semiclassical collapse proceeds we show that the very formation of a trapping horizon can be seriously questioned for a large set of, possibly realistic, scenarios. We emphasize that in principle the theoretical framework of semiclassical gravity certainly allows the formation of trapping horizons. What we are questioning here is the more subtle point of whether or not the standard black hole picture is appropriate for describing the end point of realistic collapse. Indeed if semiclassical physics were in some cases to prevent formation of the trapping horizon, then this suggests the possibility of new collapsed objects which can be much less problematic, making it unnecessary to confront the information paradox or the runaway end point problem.

We present a multipolar analysis of the gravitational recoil computed in recent numerical simulations of binary black hole coalescence, for both unequal masses and nonzero, nonprecessing spins. We show that multipole moments up to and including $\ell =4$ are sufficient to accurately reproduce the final recoil velocity (within $\simeq 2\%$) and that only a few dominant modes contribute significantly to it (within $\simeq 5\%$). We describe how the relative amplitudes, and more importantly, the relative phases, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ringdown phases. We also find that the numerical results can be reproduced by an “effective Newtonian” formula for the multipole moments obtained by replacing the radial separation in the Newtonian formulas with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasinormal modes. Analytic formulas, obtained by expressing the multipole moments in terms of the fundamental quasinormal modes of a Kerr black hole, are able to explain the onset and amount of “antikick” for each of the simulations. Lastly, we apply this multipolar analysis to help explain the remarkable difference between the amplitudes of planar and nonplanar kicks for equal-mass spinning black holes.

We consider a 3-brane embedded in a warped 5-dimensional background with a dilaton and a Kalb-Ramond 2-form. We show that it is possible to find static solutions of the form of the charged dS/AdS-like black hole with horizon which could have a negative mass parameter. The motion of the 3-brane in this bulk generates an effective 4-dimensional bouncing cosmology induced by the negative dark radiation term. This model avoids the instability that arises for the bouncing brane in a Reissner-Nordstrøm-AdS bulk.

Future space astrometry missions are planned to measure positions and/or parallaxes of celestial objects with an accuracy of the order of the microarcsecond. At such a level of accuracy, it will be indispensable to take into account the influence of the mass multipole structure of the giant planets on the bending of light rays. Within the parametrized post-Newtonian formalism, we present an algorithmic procedure enabling us to determine explicitly this influence on a light ray connecting two points located at a finite distance. Then we specialize our formulas in the cases where (1) the light source is located at space infinity, (2) both the light source and the observer are located at space infinity. We examine in detail the cases where the unperturbed ray is in the equatorial plane or in a meridian plane.

Usual inflation is realized with a slow rolling scalar field minimally coupled to gravity. In contrast, we consider dynamics of a scalar with a flat effective potential, conformally coupled to gravity. Surprisingly, it contains an attractor inflationary solution with the rapidly rolling inflaton field. We discuss models with the conformal inflaton with a flat potential (including hybrid inflation). There is no generation of cosmological fluctuations from the conformally coupled inflaton. We consider realizations of modulated (inhomogeneous reheating) or curvaton cosmological fluctuations in these models. We also implement these unusual features for the popular string-theoretic warped inflationary scenario, based on the interacting $D3$-$\overline{D}3$ branes. The original warped brane inflation suffers a large inflaton mass due to conformal coupling to 4-dimensional gravity. Instead of considering this as a problem and trying to cure it with extra engineering, we show that warped inflation with the conformally coupled, rapidly rolling inflaton is yet possible with $N=37$ efoldings, which requires low-energy scales 1–100 TeV of inflation. Coincidentally, the same warping numerology can be responsible for the hierarchy. It is shown that the scalars associated with angular isometries of the warped geometry of compact manifold (e.g. $S^3$ of Klebanov-Strassler (KS) geometry) have solutions identical to conformally coupled modes and also cannot be responsible for cosmological fluctuations. We discuss other possibilities.

Mass bounds on dark matter (DM) candidates are obtained for particles that decouple in or out of equilibrium while ultrarelativistic with arbitrary isotropic and homogeneous distribution functions. A coarse grained Liouville invariant primordial phase-space density $\mathcal{D}$ is introduced which depends solely on the distribution function at decoupling. The density $\mathcal{D}$ is explicitly computed and combined with recent photometric and kinematic data on dwarf spheroidal satellite galaxies in the Milky Way (dShps) and the observed DM density today yielding upper and lower bounds on the mass, primordial phase-space densities, and velocity dispersion of the DM candidates. Combining these constraints with recent results from $N$-body simulations yields estimates for the mass of the DM particles in the range of a few keV. We establish in this way a direct connection between the microphysics of decoupling in or out of equilibrium and the constraints that the particles must fulfill to be suitable DM candidates. If chemical freeze-out occurs before thermal decoupling, light bosonic particles can Bose condense. We study such Bose-Einstein condensate (BEC) as a dark matter candidate. It is shown that, depending on the relation between the critical ($T_c$) and decoupling ($T_d$) temperatures, a BEC light relic could act as cold DM but the decoupling scale must be higher than the electroweak scale. The condensate hastens the onset of the nonrelativistic regime and tightens the upper bound on the particle’s mass. A nonequilibrium scenario which describes particle production and partial thermalization, sterile neutrinos produced out of equilibrium, and other DM models is analyzed in detail and the respective bounds on mass, primordial phase-space density, and velocity dispersion are obtained. Thermal relics with $m\sim \mathrm{\text{few}}\mathrm{keV}$ that decouple when ultrarelativistic and sterile neutrinos produced resonantly or nonresonantly lead to a primordial phase-space density compatible with cored dShps and disfavor cusped satellites. Light Bose-condensed DM candidates yield phase-space densities consistent with cores and if $T_c\gg T_d$ also with cusps. Phase-space density bounds on particles that decoupled nonrelativistically combined with recent results from $N$-body simulations suggest a potential tension for WIMPs with $m\sim 100\mathrm{GeV}$, $T_d\sim 10\mathrm{MeV}$.

We describe the design and performance of a new source of polarized spins that can be employed in experiments that search for macroscopic interactions between particles with intrinsic spin. In this article we concentrate on the analysis of the performance of the spin source in generating putative scalar-pseudoscalar forces. We outline two methods of calculating the magnitude of such forces and compare the predictions of the models. We discuss the manufacture of the spin source and the measurements that we have carried out in order to place upper limits on systematic effects that would limit the sensitivity of such searches. We have shown, in a recent article to Physical Review Letters [G. D. Hammond, C. C. Speake, C. Trenkel, and A. Pulido-Patón, Phys. Rev. Lett. 98, 081101 (2007)], that the combination of the spin source together with the torque sensitivity of our torsion balance improves constraints on the coupling strength of macroscopic scalar-pseudoscalar interactions by 10 orders of magnitude at a range of 1 mm. This paper further supports that work and provides a detailed description and characterization of the spin source.

We present a detailed study of the Higgs sector within an extension of the minimal supersymmetric standard model that includes one complex Higgs triplet ($\mathrm{MSSM}+1\mathrm{CHT}$). The model spectrum includes three singly charged Higgs bosons as well as three $CP$-even (or scalar) and two $CP$-odd (or pseudoscalar) neutral Higgs bosons. We present an approximated calculation of the one-loop radiative corrections to the neutral $CP$-even Higgs masses ($m_{H_i^0}$) and the couplings $H_i^0{Z}^0{Z}^0$ ($i=1$, 2, 3), which determine the magnitude of the Higgs-strahlung processes $e^{+}{e}^{-}\to Z^0{H}_i^0$. Limits from LEP2 are then considered, in order to obtain bounds on the neutral Higgs sector. Further, we also include the experimental limits from LEP2 on $e^{+}{e}^{-}\to H^{+}{H}^{-}$ and those on $\mathrm{BR}(t\to b{H}^{+})$ from Tevatron, to derive bounds on the mass of the two lightest charged Higgs bosons ($H_1^{\pm }$ and $H_2^{\pm }$). Concerning the latter, we find some cases, where $m_{H_1^{\pm }}\simeq 90\mathrm{GeV}$, that are not excluded by any experimental bound, even for large values of $\tan \beta$, so that they should be looked for at the Large Hadron Collider (LHC).

If scale invariance is a classical symmetry then both the Planck scale and the weak scale should emerge as quantum effects. We show that this can be realized in simple scale invariant theories with a hidden sector. The weak/Planck scale hierarchy emerges in the (technically natural) limit in which the hidden sector decouples from the ordinary sector. In this limit, finite corrections to the weak scale are consequently small, while quadratic divergences are absent by virtue of classical scale invariance, so there is no hierarchy problem.

Gauge singlet extensions of the standard model (SM) scalar sector may help remedy its theoretical and phenomenological shortcomings while solving outstanding problems in cosmology. Depending on the symmetries of the scalar potential, such extensions may provide a viable candidate for the observed relic density of cold dark matter or a strong first order electroweak phase transition needed for electroweak baryogenesis. Using the simplest extension of the SM scalar sector with one real singlet field, we analyze the generic implications of a singlet-extended scalar sector for Higgs boson phenomenology at the Large Hadron Collider (LHC). We consider two broad scenarios: one in which the neutral SM Higgs and singlet mix and the other in which no mixing occurs and the singlet can be a dark matter particle. For the first scenario, we analyze constraints from electroweak precision observables and their implications for LHC Higgs phenomenology. For models in which the singlet is stable, we determine the conditions under which it can yield the observed relic density, compute the cross sections for direct detection in recoil experiments, and discuss the corresponding signatures at the LHC.

In this paper we extend the work synthetically presented by M. Baldicchi, A. V. Nesterenko, G. M. Prosperi, D. V. Shirkov, and C. Simolo [Phys. Rev. Lett. 99, 242001 (2007)] and give theoretical details and a complete set of numerical results. We exploit calculations within a Bethe-Salpeter (BS) formalism adjusted for QCD, in order to extract an experimental strong coupling ${\alpha }_{\mathrm{s}}^{\exp }(Q^2)$ below 1 GeV by comparison with the meson spectrum. The BS potential follows from a proper ansatz on the Wilson loop to encode confinement and is the sum of a one-gluon-exchange term and a confinement term. Besides, the common perturbative strong running coupling is replaced by the ghost-free expression ${\alpha }_{\mathrm{E}}(Q^2)$ according to the prescription of analytic perturbation theory (APT). The agreement of ${\alpha }_{\mathrm{s}}^{\exp }(Q^2)$ with the APT coupling ${\alpha }_{\mathrm{E}}(Q^2)$ turns out to be reasonably good from 1 GeV down to 200 MeV, thus confirming quantitatively the validity of the APT prescription in this range. Below this scale, the experimental points could give a hint on the vanishing of ${\alpha }_{\mathrm{s}}(Q^2)$ as $Q^2$ approaches zero. This infrared behavior would be consistent with some lattice results as well as with the massive modification of the APT approach. As a main result, we claim that the combined BS-APT theoretical scheme provides quite satisfactory correlated understanding of very high and rather low energy phenomena from a few hundred MeV to a few hundred GeV.

Recent discoveries of the ${\Xi }_b$, ${\Sigma }_b$, and ${\Sigma }_b^{*}$ baryons at the Tevatron are in good agreement with model-independent mass predictions made a decade ago based on a combined expansion in $1/N_c$, $1/m_Q$, and $SU(3)$ flavor symmetry breaking. Using the new experimental data as input, mass predictions for the undiscovered bottom baryons ${\Xi }_b^{\prime }$, ${\Xi }_b^{*}$, ${\Omega }_b$, and ${\Omega }_b^{*}$ and for many unmeasured bottom baryon mass splittings are updated. The observed ground state charm baryons exhibit the mass hierarchy previously predicted by the $1/N_c$, $1/m_Q$, and $SU(3)$ flavor-breaking expansion.

In the framework of type II seesaw mechanism we discuss the number of sterile right-handed Majorana neutrinos being the warm dark matter (WDM). When the type II seesaw mass term $M_{\nu }^{\mathrm{II}}$ is far less than the type I seesaw mass term $M_{\nu }^{\mathrm{I}}$, only one of three sterile neutrinos may be the WDM particle. On the contrary, the WDM particles may contain all sterile neutrinos. If $M_{\nu }^{\mathrm{II}}\sim M_{\nu }^{\mathrm{I}}$, the allowed number is not more than $\mathcal{N}-1$ for $\mathcal{N}$ sterile neutrinos. It is worthwhile to stress that three different types of neutrino mass spectrum are permitted when $M_{\nu }^{\mathrm{II}}\gg M_{\nu }^{\mathrm{I}}$ and $M_{\nu }^{II}\sim M_{\nu }^I$.