We study the covariant holographic entropy bound from an operational standpoint. Therefore we consider the physical limit for observations on a light sheet. A light sheet is a particular null hypersurface, and the natural measuring apparatus is a screen. By considering the physical properties of the screen—as dictated by quantum mechanics—we derive an uncertainty relation. This connects the number of bits of decoded information on the light sheet to two geometric uncertainties: the uncertainty on the place where the bits are located and the uncertainty on the local expansion of the light sheet. From this relation we can argue a local operational version of the (generalized) covariant entropy bound: The maximum number of bits decoded on a light-sheet interval goes like the area difference (in Planck units) of the initial and final surface spanned by the light rays.

We reconsider Sommerfeld-enhanced annihilation of dark matter (DM) into leptons to explain PAMELA and Fermi electron and positron observations, in light of possible new effects from substructure. There is strong tension between getting a large enough lepton signal while respecting constraints on the fluxes of associated gamma rays; we show how DM annihilations within subhalos can get around these constraints. Specifically, if most of the observed lepton excess comes from annihilations in a nearby (within 2 kpc) subhalo along a line of sight toward the galactic center, it is possible to match both the lepton and gamma ray observations. We demonstrate that this can be achieved in a simple class of particle physics models in which the DM annihilates via a hidden leptophilic U(1) vector boson, with explicitly computed Sommerfeld enhancement factors. Gamma ray constraints on the main halo annihilations (and cosmic microwave background constraints from the era of decoupling) require the annihilating component of the DM to be subdominant, of order ${10}^{-2}–{10}^{-3}$ of the total DM density.

We propose a nonlocal scalar-tensor model of gravity with pseudodifferential operators inspired by the effective action of $p$-adic string and string field theory on flat spacetime. An infinite number of derivatives act both on the metric and scalar field sector. The system is localized via the diffusion equation approach and its cosmology is studied. We find several exact dynamical solutions, also in the presence of a barotropic fluid, which are stationary in the diffusion flow. In particular, and contrary to standard general relativity, there exist solutions with exponential and power-law scale factor also in an open universe, as well as solutions with sudden future singularities or a bounce. Also, from the point of view of quantum field theory, spontaneous symmetry breaking can be naturally realized in the class of actions we consider.

In this paper we consider a unique model of inflation where the universe undergoes rapid asymmetric oscillations, each cycle lasting $\sim {10}^6$ Planck times. Over many, many cycles the space-time expands to mimic the standard inflationary scenario. Moreover, these rapid oscillations leave a distinctive periodic signature in $\ln k$ in the primordial power spectrum, where $k$ denotes the comoving scale. Although the cyclic-inflation model contains additional parameters as compared to the standard power-law spectrum, the improvement to the fit of the 7-year WMAP data is significant.

$CP$ violation in the spin-spin correlations in chargino production and subsequent two-body decay into a tau and a tau-sneutrino is studied at the ILC. From the normal polarization of the tau, an asymmetry is defined to test the $CP$-violating phase of the higgsino mass parameter $\mu$. Asymmetries of more than $\pm 70\%$ are obtained, also in scenarios with heavy first and second generation sfermions. Bounds on the statistical significances of the $CP$ asymmetries are estimated. As a result, the normal tau polarization in the chargino decay is one of the most sensitive probes to constrain or measure the phase ${\phi }_{\mu }$ at the ILC, motivating further detailed experimental studies.

We show that small soft terms can create a supersymmetry breaking minimum along a pseudoflat direction of a hidden sector which would otherwise be incapable of spontaneous supersymmetry breaking. As this minimum lies along a pseudoflat direction, with nonzero F- or D-terms, the resultant supersymmetry breaking in the hidden sector can be orders of magnitude greater than the soft terms which created the minimum. This opens new avenues for building models of gauge mediation, may have consequences for the cosmology of hidden sectors, and strengthens the case for multiple supersymmetry breaking sectors.

Understanding the underlying mechanisms causing rapid thermalization deduced for high-energy heavy ion collisions is still a challenge. To estimate the thermalization time, entropy growth for classical Yang-Mills theories is studied, based on the determination of Lyapunov exponents. Distinct regimes for short, medium and long sampling times are characterized by different properties of their spectrum of Lyapunov exponents. Clarifying the existence of these regimes and their implications for gauge-field dynamics is one of the results of this article. As a phenomenological application we conclude that for pure gauge theories with random initial conditions thermalization occurs within a few $\mathrm{fm}/c$, an estimate which can be reduced by the inclusion of fermions, specific initial conditions, etc.

The strong decay properties of the newly observed $D(2550)$, $D(2600)$, $D(2750)$, and $D(2760)$ are studied in a constituent quark model. It is predicted that the $D(2760)$ and $D(2750)$ seem to be two overlapping resonances. The $D(2760)$ could be identified as the $1{}^{3}D_3$ with $J^P=3^{-}$, while the $D(2750)$ is most likely to be the high-mass mixed state $|1D_2{}^{\prime }{⟩}_H$ ($J^P=2^{-}$) via the $1{}^{1}D_2\mathrm{\text{−}}1{}^{3}D_2$ mixing. The $D(2600)$ favors the low-mass mixed state $|(SD{)}_1{⟩}_L$ ($J^P=1^{-}$) via the $1{}^{3}D_1\mathrm{\text{−}}2{}^{3}S_1$ mixing. The $D(2550)$ as the $2{}^{1}S_0$ assignment bears controversies for its too-broad width given in experiments.

The running charm-quark mass in the $\overline{\mathrm{MS}}$ scheme is determined from weighted finite energy QCD sum rules involving the vector current correlator. Only the short distance expansion of this correlator is used, together with integration kernels (weights) involving positive powers of $s$, the squared energy. The optimal kernels are found to be a simple pinched kernel and polynomials of the Legendre type. The former kernel reduces potential duality violations near the real axis in the complex $s$ plane, and the latter allows us to extend the analysis to energy regions beyond the end point of the data. These kernels, together with the high energy expansion of the correlator, weigh the experimental and theoretical information differently from e.g. inverse moments finite energy sum rules. Current, state of the art results for the vector correlator up to four-loop order in perturbative QCD are used in the finite energy sum rules, together with the latest experimental data. The integration in the complex $s$ plane is performed using three different methods: fixed order perturbation theory, contour improved perturbation theory, and a fixed renormalization scale $\mu$. The final result is ${\overline{m}}_c(3\mathrm{GeV})=1008\pm 26\mathrm{MeV}$, in a wide region of stability against changes in the integration radius $s_0$ in the complex $s$ plane.

Searches for a heavy standard model Higgs boson focus on the “gold plated mode” where the Higgs decays to two leptonic $Z$ bosons. This channel provides a clean signature, in spite of the small leptonic branching ratios. We show that using fat jets the semileptonic $ZZ$ mode significantly increases the number of signal events with a similar statistical significance as the leptonic mode.

We discuss the isospin symmetry breaking (ISB) of the valence- and sea-quark distributions between the proton and the neutron in the framework of the chiral quark model. We assume that isospin symmetry breaking is the result of mass differences between isospin multiplets and then analyze the effects of isospin symmetry breaking on the Gottfried sum rule and the NuTeV anomaly. We show that, although both flavor asymmetry in the nucleon sea and the ISB between the proton and the neutron can lead to the violation of the Gottfried sum rule, the main contribution is from the flavor asymmetry in the framework of the chiral quark model. We also find that the correction to the NuTeV anomaly is in an opposite direction, so the NuTeV anomaly cannot be removed by isospin symmetry breaking in the chiral quark model. It is remarkable that our results of ISB for both valence- and sea-quark distributions are consistent with the Martin-Roberts-Stirling-Thorne parametrization of quark distributions.

Neutrinos propagating through matter may participate in forward coherent neutral-current–like scattering arising from nonstandard interactions as well as from the Mikheyev-Smirnov-Wolfenstein matter potential $V_e$. We show that at fixed long baselines through matter of constant density, the nonstandard interaction potential ${ϵ}_{\mu \tau }{V}_e$ can contribute an additional term to the oscillation phase whose sign differs for ${\overline{\nu }}_{\mu }$ versus ${\nu }_{\mu }$ propagation in matter. Its presence can cause different apparent $\Delta m^2$ to be erroneously inferred on the basis of oscillations in vacuum, with values lying above (for ${\overline{\nu }}_{\mu }$) or below (for ${\nu }_{\mu }$) the actual $\Delta m_{32}^2$ for the case where ${ϵ}_{\mu \tau }$ is predominantly real-valued and of sign opposite to $\Delta m_{32}^2$. A nonstandard interaction scenario invoking only $\Re ({ϵ}_{\mu \tau })$ is shown to be capable of accounting for a disparity recently reported between oscillation survival for ${\overline{\nu }}_{\mu }$ and ${\nu }_{\mu }$ fluxes measured at 735 km by the MINOS experiment. Implications for mantle traversal by atmospheric neutrinos are examined. The nonstandard interaction matter potential with nonmaximal mixing could evade conventional atmospheric neutrino analyses which do not distinguish ${\nu }_{\mu }$ from ${\overline{\nu }}_{\mu }$ on an event-by-event basis.

We study a new class of solutions of three-dimensional topological massive gravity. These solutions can be taken as nonextremal black holes, with their extremal counterparts being discrete quotients of spacelike warped ${\mathrm{AdS}}_3$ along the $U(1{)}_L$ isometry. We study the thermodynamics of these black holes and show that the first law is satisfied. We also show that for consistent boundary conditions, the asymptotic symmetry generators form only one copy of the Virasoro algebra with central charge $c_L=\frac{4\nu \ell }{G({\nu }^2+3)}$, with which the Cardy formula reproduces the black hole entropy. We compute the real-time correlators of scalar perturbations and find a perfect match with the dual conformal field theory (CFT) predictions. Our study provides a novel example of warped AdS/CFT correspondence: the self-dual warped ${\mathrm{AdS}}_3$ black hole is dual to a CFT with nonvanishing left central charge. Moreover, our investigation suggests that the quantum topological massive gravity asymptotic to the same spacelike warped ${\mathrm{AdS}}_3$ in different consistent ways may be dual to different two-dimensional CFTs.

A main scientific output of the LISA Pathfinder mission is to provide a noise model that can be extended to the future gravitational wave observatory, LISA. The success of the mission depends thus upon a deep understanding of the instrument, especially the ability to correctly determine the parameters of the underlying noise model. In this work we estimate the parameters of a simplified model of the LISA Technology Package instrument. We describe the LISA Technology Package by means of a closed-loop model that is used to generate the data, both injected signals and noise. Then, parameters are estimated using a Bayesian framework, and it is shown that this method reaches the optimal attainable error, the Cramér-Rao bound. We also address an important issue for the mission: how to efficiently combine the results of different experiments to obtain a unique set of parameters describing the instrument.

We revisit the problem of the hidden sector Landau pole in the pyramid scheme. There is a fixed line in the plane of hidden sector gauge coupling and Yukawa couplings between the trianon fields. We postulate that the couplings flow to this line, at a point where the hidden sector gauge coupling is close to the strong coupling edge of its perturbative regime. Below the masses of the heavier trianons, the model quickly flows to a confining $N_F=N_C=3$ supersymmetric gauge theory, as required by phenomenological considerations. We study possible discrete $R$ symmetries, which guarantee, among other things, that the basin of attraction of the fixed line has full codimension in the space of $R$-allowed couplings. The Yukawa couplings required to get the fixed line violate the pyrma-baryon symmetries we invoked in previous work to find a dark matter candidate. Omitting one of them, we have a dark matter candidate, and an acceptable renormalization group flow down from the unification scale, if the confinement scale of the hidden sector group is lowered from 5 to 2 TeV. However, we cannot find anomaly-free symmetries, which guarantee a set of pyrma-baryon violating couplings that eliminate the Landau pole, but do not allow a supersymmetry preserving vacuum of the model. We can do this with only one pyrma-baryon violating coupling, but this lowers the confinement scale to 900 GeV, which may already be ruled out due to light hidden sector baryons.

A heatbath algorithm is proposed for pure $\mathrm{SU}(N)$ lattice gauge theory based on the Manton action of the plaquette element for general gauge group $N$. Comparison is made to the Metropolis thermalization algorithm using both the Wilson and Manton actions. The heatbath algorithm is found to outperform the Metropolis algorithm in both execution speed and decorrelation rate. Results, mostly in $D=3$, for $N=2$ through 5 at several values for the inverse coupling are presented.

We introduce a model of SU(2) and U(1) vector fields with a local U(2) symmetry. Its action can be obtained in the London limit of a gauge invariant regularization involving two scalar fields. Evidence from lattice simulations of the model supports a (zero-temperature) SU(2) deconfining phase transition through breaking of the SU(2) center symmetry, and a massive vector boson triplet is found in the deconfined phase.

The Newtonian limit of the most general fourth-order gravity is performed with the metric approach in the Jordan frame with no gauge condition. The most general theory with fourth-order differential equations is obtained by generalizing the $f(R)$ term in the action with a generic function containing two other curvature invariants: the Ricci square ($R_{\alpha \beta }{R}^{\alpha \beta }$) and the Riemann square ($R_{\alpha \beta \gamma \delta }{R}^{\alpha \beta \gamma \delta }$). The spherically symmetric solutions of the metric tensor present Yukawa-like spatial behavior, but now one has two characteristic lengths. At Newtonian order any function of curvature invariants gives us the same outcome like the so-called quadratic Lagrangian of gravity. From the Gauss-Bonnet invariant one will have an incomplete interpretation of the solutions and the absence of a possible third characteristic length linked to the Riemann square contribution. From the analysis of metric potentials, generated by a pointlike source, one has a constraint condition on the derivatives of $f$ with respect to scalar invariants.

We construct a nonrelativistic wave equation for spinning particles in the noncommutative space (in a sense, a $\theta$ modification of the Pauli equation). To this end, we consider the nonrelativistic limit of the $\theta$-modified Dirac equation. To complete the consideration, we present a pseudoclassical model (à la Berezin-Marinov) for the corresponding nonrelativistic particle in the noncommutative space. To justify the latter model, we demonstrate that its quantization leads to the $\theta$-modified Pauli equation. We extract $\theta$-modified interaction between a nonrelativistic spin and a magnetic field from such a Pauli equation and construct a $\theta$ modification of the Heisenberg model for two coupled spins placed in an external magnetic field. In the framework of such a model, we calculate the probability transition between two orthogonal Einstein-Podolsky-Rosen states for a pair of spins in an oscillatory magnetic field and show that some of such transitions, which are forbidden in the commutative space, are possible due to the space noncommutativity. This allows us to estimate an upper bound on the noncommutativity parameter.