We provide an algebraic way to calculate the quasinormal modes of a black hole, which possesses a hidden conformal symmetry. We construct an infinite tower of quasinormal modes from the highest-weight mode, in a simple and elegant way. For the scalar, the hidden conformal symmetry manifests itself in the fact that the scalar Laplacian could be rewritten in terms of the $SL(2,R)$ quadratic Casimir. For the vector and the tensor, the hidden conformal symmetry acts on them through Lie derivatives. We show that for three-dimensional black holes, with an appropriate combination of the components, the radial equations of the vector and the tensor could be written in terms of the Lie-induced quadratic Casimir. This makes the algebraic construction of the quasinormal modes feasible. Our results are in good agreement with the previous study.

Stringent limits on the Myers-Pospelov timelike parameter for photons $\xi <{10}^{-15}$ coming from astrophysical tests suggest exploring more general preferred backgrounds, such as spacelike and lightlike. We take some steps in this direction. We allow the external four vector $n$ characterizing the Lorentz symmetry breaking to have arbitrary directions in spacetime. We study the consistency for the effective field theories in each privileged frame by demanding causality, stability, and analyticity. When specializing to a timelike background we found runaway solutions leading to causality and unitarity violations. We show that the lightlike theory is a higher-derivative theory with more degrees of freedom and nonanalytic solutions leading to instabilities when interactions are turned on. We demonstrate by explicit calculation that both stability and analyticity are preserved for the purely spacelike case while microcausality is highly suppressed. This new anisotropic model opens the possibility to play a role in the search for Planck-scale effects.

Nonprojectable Hořava gravity for a spherically symmetric configuration with $\lambda =1$ exhibits an infinite set of solutions parametrized by a generic function $g^2(r)$ for the radial component of the shift vector. In the IR limit the infinite set of solutions corresponds to the invariance of general relativity under a space-time reparametrization. In general, not being a coordinate transformation, the symmetry in the action responsible for the infinite set of solutions does not have a clear physical interpretation. Indeed it is broken by the matter term in the action. We study the behavior of the solutions for generic values of the parameter $g^2(r)$.

We study families of time-independent maximal and $1+\log $ foliations of the Schwarzschild-Tangherlini spacetime, the spherically symmetric vacuum black hole solution in $D$ spacetime dimensions, for $D\ge 4$. We identify special members of these families for which the spatial slices display a trumpet geometry. Using a generalization of the $1+\log $ slicing condition that is parameterized by a constant $n$ we recover the results of Nakao, Abe, Yoshino, and Shibata in the limit of maximal slicing. We also construct a numerical code that evolves the Baumgarte-Shapiro-Shibata-Nakamura equations for $D=5$ in spherical symmetry using moving-puncture coordinates and demonstrate that these simulations settle down to the trumpet solutions.

We investigate a first-order phase transition from hadronic matter to antikaon condensed matter during the cooling stage of protoneutron stars. The phase transition proceeds through the thermal nucleation of antikaon condensed matter. In this connection we study the effect of shear viscosity on the thermal nucleation rate of droplets of antikaon condensed matter. Here we adopt the same equation of state for the calculation of shear viscosity and thermal nucleation time. We compute the shear viscosity of neutron star matter composed of neutrons, protons, electrons, and muons using the relativistic mean field model. The prefactor in the nucleation rate, which includes the shear viscosity, is enhanced by several orders of magnitude compared with the $T^4$ approximation of earlier calculations. Consequently the thermal nucleation time in the $T^4$ approximation overestimates our result. Further, the thermal nucleation of an antikaon droplet might be possible in our case for surface tension smaller than $20\mathrm{MeV}{\mathrm{fm}}^{-2}$.

We calculate the cosmic microwave background bispectrum of vector modes induced from primordial magnetic fields. We take into account the full angular dependence of the bispectrum and discuss the amplitude and also the shape of the bispectrum in $\ell$ space. In the squeezed limit as ${\ell }_1={\ell }_2\gg {\ell }_3$, we estimate a typical values of the normalized reduced bispectrum as ${\ell }_1({\ell }_1+1){\ell }_3({\ell }_3+1)|b_{{\ell }_1{\ell }_2{\ell }_3}|\sim 2\times {10}^{-19}$, for the strength of the primordial magnetic field smoothed on 1 Mpc scale $B_{1\mathrm{Mpc}}=4.7\mathrm{nG}$ assuming a nearly scale-invariant spectrum of magnetic fields. We find that a constraint on the magnetic field strength will be roughly estimated as $B_{1\mathrm{Mpc}}<10\mathrm{nG}$, if PLANCK places a limit on the nonlinearity parameter of local-type configuration as $|f_{\mathrm{NL}}^{\mathrm{local}}|<5$.

At LHC a large number of $b$-flavored baryons will be produced. In this paper we propose new baryon modes to determine the photon helicity of the penguin transition $b\to s\gamma$. The baryons ${\Xi }_b^{-}$ and ${\Xi }_b^0$, already observed, have a number of good features. The charged baryon ${\Xi }_b^{-}$ will decay into the mode ${\Xi }^{-}\gamma$, where the ground state hyperon ${\Xi }^{-}({\frac{1}{2}}^{+})$, although it will decay most of the time outside the detector, can be detected because it is charged. We emphasize, however, that the initial transverse polarization of ${\Xi }_b$ has to be known in both cases. To determine this parameter through the transition ${\Xi }_b\to J/\Psi \Xi$, we distinguish between different cases, and emphasize that in some situations one needs theoretical input on the asymmetry parameter ${\alpha }_{{\Xi }_b}$ of the primary decay. A fortiori the same considerations apply to the case of the ${\Lambda }_b$.

We show that colliders can impose strong constraints on models of dark matter, in particular, when the dark matter is light. We analyze models where the dark matter is a fermion or scalar interacting with quarks and/or gluons through an effective theory containing higher dimensional operators which represent heavier states that have been integrated out of the effective field theory. We determine bounds from existing Tevatron searches for monojets as well as expected LHC reaches for a discovery. We find that colliders can provide information which is complementary or in some cases even superior to experiments searching for direct detection of dark matter through its scattering with nuclei. In particular, both the Tevatron and the LHC can outperform spin-dependent searches by an order of magnitude or better over much of the parameter space, and if the dark matter couples mainly to gluons, the LHC can place bounds superior to any spin-independent search.

We compute the nonzero temperature free energy up to the order $g^6\ln (1/g)$ in the coupling constant for vectorlike $SU(N)$ gauge theories featuring matter transforming according to different representations of the underlying gauge group. The number of matter fields, i.e. flavors, is arranged in such a way that the theory develops a perturbative stable infrared fixed point at zero temperature. Because of large distance conformality we trade the coupling constant with its fixed point value and define a reduced free energy which depends only on the number of flavors, colors, and matter representation. We show that the reduced free energy changes sign, at the second, fifth, and sixth order in the coupling, when decreasing the number of flavors from the upper end of the conformal window. If the change in sign is interpreted as a signal of an instability of the system then we infer a critical number of flavors. Surprisingly this number, if computed to the order $g^2$, agrees with previous predictions for the lower boundary of the conformal window for nonsupersymmetric gauge theories. The higher order results tend to predict a higher number of critical flavors. These are universal properties, i.e. they are independent of the specific matter representation.

Since the recent results of direct detection experiments at low mass, many authors have revisited the case of light (1–10) GeV weakly interacting massive particles. In particular, there have been a few attempts to explain the results from the DAMA/LIBRA, CDMS and/or CoGeNT experiments by invoking neutralinos lighter than 15 GeV. Here we show that in the minimal supersymmetric standard mode (MSSM), such light particles are completely ruled out by the Tevatron limits on the mass of the pseudoscalar Higgs. On the contrary, in the next-to-minimal supersymmetric standard model (NMSSM), we find that light neutralinos could still be viable candidates. In fact, in some cases, they may even have an elastic scattering cross section on nucleons in the range that is needed to explain either the DAMA/LIBRA, CoGeNT or CDMS recent results. Finally, we revisit the lowest limit on the neutralino mass in the MSSM and find that neutralinos should be heavier than $\sim 28\mathrm{GeV}$ to evade present experimental bounds.

The use of inclusive $M_{T2}$ distribution for sparticle mass determination is discussed. We define new parameters $M_{T2}(\min )$ and $M_{T2}^{\mathrm{mod}}(\min )$, which are a kind of minimum of subsystem $M_{T2}$ values. Their end points are less affected by initial state radiations. We demonstrate that both $m_{\tilde{q}}$ and $m_{\tilde{g}}$ can be extracted from the end points of the distributions in the wide region of parameter space expected in constrained minimal supersymmetric standard model. We also present a comparison with $M_{T\mathrm{Gen}}$ distributions.

We discuss leptogenesis within a TeV-scale inverse seesaw model for neutrino masses where the seesaw structure is guaranteed by an $SO(10)$ symmetry. Contrary to the TeV-scale type-I gauged seesaw, the constraints imposed by successful leptogenesis in these models are rather weak and allow for the extra gauge bosons $W_R$ and $Z^{\prime }$ to be in the LHC accessible range. The key differences in the inverse seesaw compared to the type-I case are (i) decay and inverse decay rates larger than the scatterings involving extra gauge bosons due to the large Yukawa couplings and (ii) the suppression of the washout due to very small lepton number breaking.

We study the effective models of chiral fields and the Polyakov loop expected to describe the dynamics responsible for the phase structure of two-flavor QCD at finite temperature and density. We consider the chiral sector described either using the linear sigma model, including the fermion vacuum fluctuations, or the Nambu-Jona-Lasinio model and study the phase diagram and determine the location of the critical point as a function of the explicit chiral symmetry breaking (i.e. the bare quark mass $m_q$). We also discuss the possible emergence of the quarkyonic phase in this model.

We study a system of an elastic ball moving in the nonrelativistic spacetime with a nontrivial causal structure produced by a wormhole-based time machine. For such a system, it is possible to formulate a simple model of the so-called “grandfather paradox”: for certain “paradoxical” initial conditions, the standard straight trajectory of the ball would self-collide inconsistently. We analyze globally consistent solutions of local equations of motion; namely, we find all trajectories with one self-collision. It is demonstrated that all standard initial conditions have a consistent evolution, including those paradoxical ones, for which the inconsistent collision-free trajectory is superseded by a special consistent self-colliding trajectory. Moreover, it is shown that for a wide class of initial conditions, more than one globally consistent evolution exist. The nontrivial causal structure thus breaks the uniqueness of the classical theory even for locally deterministic physical laws.

We study the dynamics of states perturbatively expanded about a harmonic system of loop quantum cosmology, exhibiting a bounce. In particular, the evolution equations for the first and second-order moments of the system are analyzed. These moments back-react on the trajectories of the expectation values of the state and hence alter the energy density at the bounce. This analysis is performed for isotropic loop quantum cosmology coupled to a scalar field with a small but nonzero constant potential, hence in a regime in which the kinetic energy of matter dominates. Analytic restrictions on the existence of dynamical coherent states and the meaning of semiclassicality within these systems are discussed. A numerical investigation of the trajectories of states that remain semiclassical across the bounce demonstrates that, at least for such states, the bounce persists and that its properties are similar to the standard case, in which the moments of the states are entirely neglected. However, the bounce density does change, implying that a quantum bounce may not be guaranteed to happen when the potential is no longer negligible.

We perform numerical simulations of large scale structure evolution in an inhomogeneous Lemaître-Tolman-Bondi (LTB) model of the Universe. We follow the gravitational collapse of a large underdense region (a void) in an otherwise flat matter-dominated Einstein–de Sitter model. We observe how the (background) density contrast at the center of the void grows to be of order one, and show that the density and velocity profiles follow the exact nonlinear LTB solution to the full Einstein equations for all but the most extreme voids. This result seems to contradict previous claims that fully relativistic codes are needed to properly handle the nonlinear evolution of large scale structures, and that local Newtonian dynamics with an explicit expansion term is not adequate. We also find that the (local) matter density contrast grows with the scale factor in a way analogous to that of an open universe with a value of the matter density ${\Omega }_M(r)$ corresponding to the appropriate location within the void.

We perform a detailed and quasi model-independent analysis of direct annihilation of dark matter into neutrinos. Considering different cases for scalar and fermionic dark matter, we identify several settings in which this annihilation is enhanced, contrary to some statements in the literature. The key point is that several restrictions of, e.g., a supersymmetric framework do not hold in general. The mass generation mechanism of the neutrinos plays an important role, too. We illustrate our considerations by two examples that are not (as usually) suppressed by the smallness of the neutrino mass, for which we also present a numerical analysis. Our results can be easily used as guidelines for model building.

Assuming the definition of the inversion problem (IP) as the exact matching of the terms in the low redshift expansion of cosmological observables calculated for different cosmological models, we solve the IP for $D_L(z)$ and the redshift spherical shell mass density $mn(z)$ for a central observer in a Lemaitre-Tolman-Bondi (LTB) space without cosmological constant and a generic $\Lambda \mathrm{CDM}$ model. We show that the solution of the IP is unique, corresponds to a matter density profile which is not smooth at the center, and that the same conclusions can be reached expanding self-consistently to any order all the relevant quantities. Contrary to the case of a single observable inversion problem, it is impossible to solve the IP (LTB vs $\Lambda \mathrm{CDM}$) for both $mn(z)$ and $D_L(z)$ while setting one of the two functions $k(r)$ or $t^b(r)$ to zero, even allowing nonsmooth matter profiles. Our conclusions are general, since they are exclusively based on comparing directly physical observables in redshift space, and do not depend on any special ansatz or restriction for the functions defining a LTB model.

Suppression in primordial power on the Universe’s largest observable scales has been invoked as a possible explanation for large-angle observations in the cosmic microwave background, and is allowed or predicted by some inflationary models. Here we investigate the extent to which such a suppression could be confirmed by the upcoming large-volume redshift surveys. For definiteness, we study a simple parametric model of suppression that improves the fit of the vanilla $\Lambda \mathrm{CDM}$ model to the angular correlation function measured by WMAP in cut-sky maps, and at the same time improves the fit to the angular power spectrum inferred from the maximum likelihood analysis presented by the WMAP team. We find that the missing power at large scales, favored by WMAP observations within the context of this model, will be difficult but not impossible to rule out with a galaxy redshift survey with large-volume ($\sim 100{\mathrm{Gpc}}^3$). A key requirement for success in ruling out power suppression will be having redshifts of most galaxies detected in the imaging survey.

Using a previous extraction of the quark Boer-Mulders distributions from semi-inclusive deep inelastic scattering data, we fit the unpolarized Drell-Yan data on the $\cos 2\varphi$ asymmetry, determining the antiquark Boer-Mulders distributions. A good agreement with the data is found in the region of low $q_T$, where the transverse-momentum factorization approach applies.