Recently, Carlip proposed a derivation of the entropy of the two-dimensional dilatonic black hole by investigating the Virasoro algebra associated with a newly introduced near-horizon conformal symmetry. We point out not only that the algebra of these conformal transformations is not well defined on the horizon, but also that the correct use of the eigenvalue of the operator $L_0$ yields vanishing entropy. It has been shown that these problems can be resolved by choosing a different basis of the conformal transformations which is regular even at the horizon. We also show the generalization of Carlip’s derivation to any higher dimensional case in pure Einstein gravity. The entropy obtained is proportional to the area of the event horizon, but it also depends linearly on the product of the surface gravity and the parameter length of a horizon segment in consideration. We finally point out that this derivation of black hole entropy is quite different from the ones proposed so far, and several features of this method and some open issues are also discussed.

We present an analysis of the electric dipole moment (EDM) of the deuteron as induced by CP-violating operators of dimension 4, 5 and 6 including ${\theta }_{\mathrm{QCD}},$ the EDMs and color EDMs of quarks, four-quark interactions and the Weinberg operator. We demonstrate that the precision goal of the EDM Collaboration’s proposal to search for the deuteron EDM, $(1\mathrm{}–3)\times {10}^{-27}e\mathrm{cm},$ will provide an improvement in sensitivity to these sources of one to two orders of magnitude relative to the existing bounds. We consider in detail the level to which CP-odd phases can be probed within the minimal supersymmetric standard model.

The Higgs boson pair production process at hadron collider provides an opportunity for performing a study of the trilinear Higgs boson self-coupling. In this paper, we analyze the pair production of a neutral Higgs boson via both gluon-gluon and $b-\overline{b}$ fusions in the littlest Higgs (LH) model at the CERN LHC. We find that in some parameter space the relative corrections of the total cross section to the SM prediction may reach a value of 24% when ${x(=4\mathrm{fv}}^{\prime }{/v}^2)=0.95\mathrm{}$ at the LHC. We conclude that if the parameter x has a value above 0.8, the relative corrections contributed by the LH model reach values beyond 8% and could be observed at the LHC.

Quark model matrix elements can be computed using bosonic operators and the holomorphic representation for the harmonic oscillator. The technique is illustrated for normal and exotic baryons for an arbitrary number of colors. The computations are much simpler than those using conventional quark model wave functions.

The cross sections describing the transverse momentum distributions of Higgs bosons are discussed within the framework of unintegrated parton distributions obtained from the Catani-Ciafaloni-Fiorani-Marchesini (CCFM) equations in the single-loop approximation. It is shown how the approximate treatment of the CCFM equations generates the standard expressions describing the soft gluon resummation effects in the corresponding cross sections. Possible differences between exact and approximate solutions of the CCFM equations are discussed on the example of the $g\overrightarrow{g}H$ fusion mechanism, which gives the dominant contribution to Higgs boson production.

In this paper we study the tachyonic inflation in brane world cosmology with Gauss-Bonnet term in the bulk. We obtain the exact solution of slow roll equations in case of exponential potential. We attempt to implement the proposal of J. E. Lidsey and N. J. Nunes [Phys. Rev. D 67, 103510 (2003)] for the tachyon condensate rolling on the Gauss-Bonnet brane and discuss the difficulties associated with the proposal.

The perturbative framework of the space-time noncommutative real scalar field theory is formulated, based on the unitary S matrix. Unitarity of the S matrix is explicitly checked order by order using the Heisenberg picture of Lagrangian formalism of the second quantized operators, with emphasis on the so-called minimal realization of the time-ordering step function and of the importance of the $\star$-time ordering. The Feynman rule is established and is presented using ${\phi }^4$ scalar field theory. It is shown that the divergence structure of space-time noncommutative theory is the same as the one of space-space noncommutative theory, while there is no UV-IR mixing problem in this space-time noncommutative theory.

We carefully analyze the contribution to the oscillations of a metallic gravitational antenna due to the interaction between the electrons of the bar and the incoming gravitational wave. To this end, we first derive the total microscopic Hamiltonian of the wave-antenna system and then compute the contribution to the attenuation factor due to the electron-graviton interaction. As compared to the ordinary damping factor, which is due to the electron viscosity, this term turns out to be totally negligible. This result confirms that the only relevant mechanism for the interaction of a gravitational wave with a metallic antenna is its direct coupling with the bar normal modes.

The profiles of the chromoelectric field generated by static quark-antiquark, $Q\overline{Q},$ and three-quark, QQQ, sources are calculated in Coulomb gauge. Using a variational ansatz for the ground state, we show that a flux tube-like structure emerges and combines to the “Y”-shape field profile for three static quarks. The properties of the chromoelectric field are, however, not expected to be the same as those of the full action density or the Wilson line and the differences are discussed.

If neutrinos have mass, they can also decay. Decay lifetimes of cosmological interest can be probed, in principle, through the detection of the redshifted, diffuse neutrino flux produced by all past supernovae—the so-called supernova relic neutrino (SRN) flux. In this work, we solve the SRN kinetic equations in the general case of three-generation flavor transitions followed by invisible (nonradiative) two-body decays. We then use the general solution to calculate observable SRN spectra in some representative decay scenarios. It is shown that, in the presence of decay, the SRN event rate can basically span the whole range below the current experimental upper bound—a range accessible to future experimental projects. Radiative SRN decays are also briefly discussed.

We study the quotients of $\mathrm{}(n+1\mathrm{})\mathrm{}$-dimensional anti–de Sitter space by one-parameter subgroups of its isometry group $\mathrm{SO}(2,n)\mathrm{}$ for general n. We classify the different quotients up to conjugation by $O(2,n).$ We find that the majority of the classes exist for all $n>~2.$ There are two special classes which appear in higher dimensions: one for $n>~3$ and one for $n>~4.$ The description of the quotient in the majority of cases is thus a simple generalization of the ${\mathrm{AdS}}_3$ quotients.

We show that eternal inflation is compatible with holography. In particular, we emphasize that if a region is asymptotically de Sitter in the future, holographic arguments by themselves place no bound on the number of past e-foldings. We also comment briefly on holographic restrictions on the production of baby universes.

Symmetry breaking can produce “Alice” strings, which alter scattered charges and carry monopole number and charge when twisted into loops. Alice behavior arises algebraically, when strings obstruct unbroken symmetries—a fragile criterion. We give a topological criterion, compelling Alice behavior or deforming it away. Our criterion, that ${\pi }_0\mathrm{}\left(H\right)\mathrm{}$ acts nontrivially on ${\pi }_1\mathrm{}\left(H\right),$ links topologically Alice strings to topological monopoles. We twist topologically Alice loops to form monopoles. We show that Alice strings of condensed matter systems (nematic liquid crystals, ${}^3\mathrm{He}-A,$ and related non-chiral Bose condensates and amorphous chiral superconductors) are topologically Alice, and support fundamental monopole charge when twisted into loops. Thus they might be observed indirectly, not as strings, but as loop-like point defects. We describe other models, showing Alice strings failing our topological criterion; and twisted Alice loops supporting deposited, but not fundamental, monopole number.

We generalize the hard-thermal-loop effective action of the equilibrium quark-gluon plasma to a nonequilibrium system which is space-time homogeneous but for which the parton momentum distribution is anisotropic. We show that the manifestly gauge-invariant Braaten-Pisarski form of the effective action can be straightforwardly generalized and we verify that it then generates all n-point functions following from collisionless gauge-covariant transport theory for a homogeneous anisotropic plasma. On the other hand, the Taylor-Wong form of the hard-thermal-loop effective action has a more complicated generalization to the anisotropic case. Already in the simplest case of anisotropic distribution functions, it involves an additional term that is gauge invariant by itself, but nontrivial also in the static limit.

The possibility of a Chern-Simons- (CS-) like term generation in an extended model of QED, in which a Lorentz and CPT non-covariant kinetic term for fermions is present, has been investigated at finite temperature and in the presence of a background color magnetic field. To this end, the photon polarization operator in an external constant axial-vector field has been considered. One-loop contributions to its antisymmetric component due to fermions in the linear order of the axial-vector field have been obtained. Moreover, the first nontrivial correction to the induced CS term due to the presence of a weak constant homogeneous color magnetic field has been derived.

We propose a simple model of extra-dimensional radius stabilization in a supersymmetric Randall-Sundrum model. In our model, we introduce only a bulk hypermultiplet and source terms (tadpole terms) on each boundary brane. With an appropriate choice of model parameters, we find that the radius can be stabilized by supersymmetric vacuum conditions. Since the radion mass can be much larger than the gravitino mass and even the original supersymmetry breaking scale, radius stability is ensured even in the presence of supersymmetry breaking. We find a parameter region in which unwanted scalar masses induced by quantum corrections through the bulk hypermultiplet and a bulk gravity multiplet are suppressed and the anomaly mediation contribution dominates.

Local Lorentz invariance violation can be realized by introducing extra tensor fields in the action that couple to matter. If the Lorentz violation is rotationally invariant in some frame, then it is characterized by an “aether,” i.e., a unit timelike vector field. General covariance requires that the aether field be dynamical. In this paper we study the linearized theory of such an aether coupled to gravity and find the speeds and polarizations of all the wave modes in terms of the four constants appearing in the most general action at second order in derivatives. We find that in addition to the usual two transverse traceless metric modes, there are three coupled aether-metric modes.

We find all higher dimensional solutions of Einstein-Maxwell theory that are the topological product of two manifolds of constant curvature. These solutions include the higher dimensional Nariai, Bertotti-Robinson and anti-Nariai solutions and the anti–de Sitter Bertotti-Robinson solutions with toroidal and hyperbolic topology (Plebański-Hacyan solutions). We give explicit results for any dimension $D>~4.$ These solutions are generated from the appropriate extremal limits of the higher dimensional near-extreme black holes in de Sitter and anti–de Sitter backgrounds. Thus, we also find the mass and charge parameters of higher dimensional extreme black holes as a function of the radius of the degenerate horizon.

For a 4-dimensional spatially flat Friedmann-Robertson-Walker universe with a scalar field $\phi \mathrm{}\left(x\right),$ potential $V\left(\phi \right)$ and constant equation of state $w=p/\rho ,$ we show that an expanding solution characterized by $\epsilon =3\mathrm{}(1+w)/2\mathrm{}$ produces the same scalar perturbations as a contracting solution with $\hat{\epsilon }=1/\epsilon .$ The same symmetry applies to both the dominant and subdominant scalar perturbation modes. This result admits a simple physical interpretation and generalizes to d spacetime dimensions if we define $\epsilon \equiv \left[\right(2d-5)+(d-1\left)w\right]/\left(d-2\right).$

By applying the Palatini approach to the $1/R$ gravity model it is possible to explain the present accelerated expansion of the Universe. Investigation of the late Universe limiting case shows that (i) due to the curvature effects the energy-momentum tensor of the matter field is not covariantly conserved; (ii) however, it is possible to reinterpret the curvature corrections as sources of the gravitational field, by defining a modified energy-momentum tensor; (iii) with the adoption of this modified energy-momentum tensor the Einstein field equations are recovered with two main modifications: the first one is the weakening of the gravitational effects of matter whereas the second is the emergence of an effective varying “cosmological constant;” (iv) there is a transition in the evolution of the cosmic scale factor from a power-law scaling $a\propto t^{11/18}$ to an asymptotically exponential scaling $a\propto \exp \mathrm{}\left(t\right);$ (v) the energy density of the matter field scales as ${\rho }_m\propto {\mathrm{}(1/a)\mathrm{}}^{36/11};$ (vi) the present age of the Universe and the decelerated-accelerated transition redshift are smaller than the corresponding ones in the cold dark matter with a cosmological constant model.