The membrane paradigm approach to black holes fixes in the vicinity of the event horizon a fictitious surface, the stretched horizon, so that the spacetime outside remains unchanged and the spacetime inside is vacuum. Using this powerful method, several black hole properties have been found and settled, such as the horizon’s viscosity, electrical conductivity, resistivity, as well as other properties. On the other hand, the Euclidean action approach to black hole spacetimes has been very fruitful in understanding black hole entropy. Combining both the Euclidean action and membrane paradigm approaches, a direct derivation of the black hole entropy is given. In the derivation, it is considered that the only fields present are the gravitational and matter fields, with no electric field.

Using a principal component basis that accommodates order unity features in the slow-roll parameters as fine as $1/10$ of a decade across more than 2 decades of the inflationary expansion, we test slow-roll and single-field inflation with the WMAP7 data. Detection of any nonzero component would represent a violation of ordinary slow roll and indicate a feature in the inflaton potential or sound speed. Although one component shows a deviation at the 98% CL, it cannot be considered statistically significant given the 20 components tested. The maximum likelihood principal component parameters only improve $2\Delta \ln L$ by 17 for the 20 parameters associated with known glitches in the WMAP power spectrum at multipoles $\ell <60$. We make model-independent predictions for the matching glitches in the polarization spectrum that would test their inflationary origin. This complete analysis for band-limited features in the source function of generalized slow roll can be used to constrain parameters of specific models of the inflaton potential without requiring a separate likelihood analysis for each choice. We illustrate its use by placing bounds on the height and width of a steplike feature in the potential proposed to explain the glitch at $20\le \ell \le 40$. Even allowing for the presence of features in the temperature spectrum, single-field inflation makes sharp falsifiable predictions for the acoustic peaks in the polarization whose violation would require extra degrees of freedom.

Single-field slow-roll inflation with a nonvacuum initial state has an enhanced bispectrum in the local limit. We numerically calculate the local-type $f_{\mathrm{NL}}$ signal in the cosmic microwave background (CMB) that would be measured for such models (including the full transfer function and 2D projection). The nature of the result depends on several parameters, including the occupation number $N_k$, the phase angle ${\theta }_k$ between the Bogoliubov parameters, and the slow-roll parameter $ϵ$. In the most conservative case, where one takes ${\theta }_k\approx {\eta }_{0}k$ (justified by physical reasons discussed within) and $ϵ\lesssim 0.01$, we find that $0<f_{\mathrm{NL}}<1.52(ϵ/0.01)$, which is likely too small to be detected in the CMB. However, if one is willing to allow a constant value for the phase angle ${\theta }_k$ and $N_k=\mathcal{O}(1)$, $f_{\mathrm{NL}}$ can be much larger and/or negative (depending on the choice of ${\theta }_k$), e.g. $f_{\mathrm{NL}}\approx 28(ϵ/0.01)$ or $-6.4(ϵ/0.01)$; depending on $ϵ$, these scenarios could be detected by Planck or a future satellite. While we show that these results are not actually a violation of the single-field consistency relation, they do produce a value for $f_{\mathrm{NL}}$ that is considerably larger than that usually predicted from single-field inflation.

The Galaxy is suspected to contain hundreds of millions of binary white dwarf systems, a large fraction of which will have sufficiently small orbital periods to emit gravitational radiation in band for space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA). LISA’s main science goal is the detection of cosmological events (supermassive black hole mergers, etc.) however the gravitational signal from the galaxy will be the dominant contribution to the data—including instrumental noise—over approximately two decades in frequency. The catalog of detectable binary systems will serve as an unparalleled means of studying the Galaxy. Furthermore, to maximize the scientific return from the mission, the data must be cleansed of the galactic foreground. We will present an algorithm that can accurately resolve and subtract $\gtrsim 10000$ of these sources from simulated data supplied by the Mock LISA Data Challenge Task Force. Using the time evolution of the gravitational wave frequency, we will reconstruct the position of the recovered binaries and show how LISA will sample the entire compact binary population in the Galaxy.

We investigate the spontaneous breaking of the Baryon ($B$) and Lepton ($L$) number at the TeV scale in supersymmetric models. A simple extension of the minimal supersymmetric standard model where $B$ and $L$ are spontaneously broken local gauge symmetries is proposed. The $B$ and $L$ symmetry breaking scales are defined by the supersymmetry breaking scale. By gauging $B$ and $L$, we understand the absence of the baryon and lepton number violating interactions of dimension four and five in the minimal supersymmetric standard model. Furthermore, we show that even though these symmetries are spontaneously broken there are no dangerous operators mediating proton decay. We discuss the main properties of the spectrum, the possible baryon number violating decays and the implications for the dark matter candidates. In this model, one can have lepton number violating signals from the decays of the right-handed neutrinos and baryon number violating signals from the decays of squarks and gauginos without conflict with the bounds coming from proton decay, $n-\overline{n}$ oscillations and dinucleon decays.

The long-standing model-independent annual modulation effect measured by the DAMA Collaboration, which fulfills all the requirements of a dark matter annual modulation signature, and the new result by the CoGeNT experiment that shows a similar behavior are comparatively examined under the hypothesis of a dark matter candidate particle interacting with the detectors’ nuclei by a coherent elastic process. The ensuing physical regions in the plane of the dark matter-particle mass versus the dark matter-particle nucleon cross-section are derived for various galactic halo models and by taking into account the impact of various experimental uncertainties. It is shown that the DAMA and the CoGeNT regions agree well between each other and are well fitted by a supersymmetric model with light neutralinos which satisfies all available experimental constraints, including the most recent results from CMS and ATLAS at the CERN Large Hadron Collider.

Current techniques cannot detect axion dark matter over much of its parameter space, particularly in the theoretically well-motivated region where the axion decay constant $f_a$ lies near the grand unified theory (GUT) and Planck scales. We suggest a novel experimental method to search for QCD axion dark matter in this region. The axion field oscillates at a frequency equal to its mass when it is a component of dark matter. These oscillations induce time varying CP-odd nuclear moments, such as electric dipole and Schiff moments. The coupling between internal atomic fields and these nuclear moments gives rise to time varying shifts to atomic energy levels. These effects can be enhanced by using elements with large Schiff moments such as the light Actinides, and states with large spontaneous parity violation, such as molecules in a background electric field. The energy level shift in such a molecule can be $\sim {10}^{-24}\mathrm{eV}$ or larger. While challenging, this energy shift may be observable in a molecular clock configuration with technology presently under development. The detectability of this energy shift is enhanced by the fact that it is a time varying shift whose oscillation frequency is set by fundamental physics, and is therefore independent of the details of the experiment. This signal is most easily observed in the sub-MHz range, allowing detection when $f_a$ is $\gtrsim {10}^{16}\mathrm{GeV}$, and possibly as low as ${10}^{15}\mathrm{GeV}$. A discovery in such an experiment would not only reveal the nature of dark matter and confirm the axion as the solution to the strong CP problem, it would also provide a glimpse of physics at the highest energy scales, far beyond what can be directly probed in the laboratory.

Hadron collider signatures of new physics are investigated in which a primary resonance is produced that decays to a secondary resonance by emitting a $W$ boson, with the secondary resonance decaying to two jets. This topology can arise in supersymmetric theories with $R$-parity violation where the lightest supersymmetric particles are either a pair of squarks, or a slepton-sneutrino pair. The resulting signal can have a cross section consistent with the $Wjj$ observation reported by the CDF Collaboration, while remaining consistent with earlier constraints. Other observables that can be used to confirm this scenario include a significant charge asymmetry in the same channel at the LHC. With strongly interacting resonances such as squarks, pair production topologies additionally give rise to four jet and $W^{+}{W}^{-}+\mathrm{\text{four}}\mathrm{\text{jet}}$ signatures, each with two equal-mass dijet resonances within the four jets.

A recent study of gamma-ray data from the Galactic center motivates the investigation of light ($\sim 7–10\mathrm{GeV}$) particle dark matter models featuring tau-lepton pairs as dominant annihilation final state. The lepton-specific two-Higgs-doublet model provides a natural framework where light, singlet scalar dark matter can pair-annihilate dominantly into tau leptons. We calculate the nucleon–dark matter cross section for singlet scalar dark matter within the lepton-specific two-Higgs-doublet model framework, and compare with recent results from direct detection experiments. We study how direct dark matter searches can be used to constrain the dark matter interpretation of gamma-ray observations, for different dominant annihilation final states. We show that models exist with the correct thermal relic abundance that could fit the claimed gamma-ray excess from the Galactic center region and have direct detection cross sections of the order of what is needed to interpret recent anomalous events reported by direct detection experiments.

Results are presented for the low-lying spectrum of $D$ and $D_s$ mesons calculated in lattice QCD using $2+1$ flavor Clover-Wilson configurations made available by the PACS-CS collaboration. For the heavy quark, the Fermilab method is employed. The main focus is $S$- and $P$-wave states of charmed and charmed-strange mesons, where previous lattice QCD results have been mostly from quenched calculations. In addition to the ground states, some excited states are extracted. To check the method, calculations of the charmonium spectrum are also carried out. For charmonium, the low-lying spectrum agrees favorably with experiment. For heavy-strange and heavy-light systems substantial differences in comparison to experiment values remain for some states.

The relativistic heavy ion program developed at RHIC and now at LHC motivated a deeper study of the properties of the quark-gluon plasma (QGP) and, in particular, the study of perturbations in this kind of plasma. We are interested on the time evolution of perturbations in the baryon and energy densities. If a localized pulse in baryon density could propagate throughout the QGP for long distances preserving its shape and without loosing localization, this could have interesting consequences for relativistic heavy ion physics and for astrophysics. A mathematical way to prove that this can happen is to derive (under certain conditions) from the hydrodynamical equations of the QGP a Korteveg-de Vries (KdV) equation. The solution of this equation describes the propagation of a KdV soliton. The derivation of the KdV equation depends crucially on the equation of state (EOS) of the QGP. The use of the simple MIT bag model EOS does not lead to KdV solitons. Recently we have developed an EOS for the QGP which includes both perturbative and nonperturbative corrections to the MIT one and is still simple enough to allow for analytical manipulations. With this EOS we were able to derive a KdV equation for the cold QGP.

We discuss the heavy quark spin structure of the recently observed “twin” resonances $Z_b(10610)$ and $Z_b(10650)$, assuming that these are mostly of a “molecular” type, i.e. that their internal dynamics is dominated by the coupling to meson pairs $B^{*}\overline{B}-B{\overline{B}}^{*}$ and $B^{*}{\overline{B}}^{*}$. We find that the state of the $b\overline{b}$ pair within the $Z_b(10610)$ and $Z_b(10650)$ resonances is a mixture of a spin-triplet and a spin-singlet of equal amplitude and with the phase orthogonal between the two resonances. Such a structure gives rise to specific relations between observable amplitudes that are in agreement with the data obtained recently by Belle. We also briefly discuss possible properties of the isotopically singlet counterparts of the newly found resonances, and also of their $C$ ($G$) parity opposites that likely exist in the same mass range near the open $B$ flavor threshold.

We analyze a class of supersymmetric $SO(10)$ grand unified theories with a type II seesaw mechanism for neutrino masses, where the contribution to the Pontecorvo-Maki-Nakagawa-Sakata matrix from the neutrino sector has an exact tribimaximal form, dictated by a broken $S_4$ symmetry. The Higgs fields that determine the fermion masses are two $\mathbf{10}$ fields and one $\mathbf{126}$ field, with the latter simultaneously contributing to neutrino as well as charged fermion masses. Fitting charged fermion masses and the Cabibbo-Kobayashi-Maskawa mixings leads to corrections to the tribimaximal mixing that determine the final Pontecorvo-Maki-Nakagawa-Sakata matrix with the predictions ${\theta }_{13}\simeq 4°–6°$ and a Dirac $CP$ phase between $-10°$ and $+15°$. We also show correlations between various mixing angles which can be used to test the model.

This article reports a measurement of the production cross section of prompt isolated photon pairs in proton-antiproton collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using the CDF II detector at the Fermilab Tevatron collider. The data correspond to an integrated luminosity of $5.36{\mathrm{fb}}^{-1}$. The cross section is presented as a function of kinematic variables sensitive to the reaction mechanisms. The results are compared with three perturbative QCD calculations: (1) a leading-order parton shower Monte Carlo, (2) a fixed next-to-leading-order calculation and (3) a next-to-leading-order/next-to-next-to-leading-log resummed calculation. The comparisons show that, within their known limitations, all calculations predict the main features of the data, but no calculation adequately describes all aspects of the data.

We devise an algebraic procedure for the evaluation of Green’s functions in $SU(N)$ Yang-Mills theory in the presence of a nontrivial background field. In the ghost-free sector the dependence of the vertex functional on the background is shown to be uniquely determined by the Slavnov-Taylor identities in terms of a certain 1-PI correlator of the covariant derivatives of the ghost and the antighost fields. At nonvanishing background this amplitude is shown to encode the quantum deformations to the tree-level background-quantum splitting. The approach only relies on the functional identities of the model (Slavnov-Taylor identities, $b$-equation, antighost equation) and thus it is valid beyond perturbation theory, and, in particular, in a lattice implementation of the background field method. As an example of the formalism we analyze the ghost two-point function and the Kugo-Ojima function in an instanton background in $SU(2)$ Yang-Mills theory, quantized in the background Landau gauge.

We investigate the effect of a large number of kinks on the gravitational power radiated by cosmic string loops. We show that the total power radiated by a loop with $N$ left-moving and right-moving kinks is proportional to $N$ and increases with the typical kink angle. We then apply these results to loops containing junctions which give rise to a proliferation of the number of sharp kinks. We show that the time of gravitational decay of these loops is smaller than previously assumed. In light of this, we revisit the gravitational wave burst predictions from a network containing such loops. We find there is no parameter regime in which the rate of individual kink bursts is enhanced with respect to standard networks. By contrast, there remains a region of parameter space for which the kink-kink bursts dominate the stochastic background. Finally, we discuss the order of magnitude of the typical number of sharp kinks resulting from kink proliferation on loops with junctions.

Extreme mass-ratio inspirals, in which a stellar-mass compact object spirals into a supermassive black hole, are prime candidates for detection with space-borne milliHertz gravitational wave detectors, similar to the Laser Interferometer Space Antenna. The gravitational waves generated during such inspirals encode information about the background in which the small object is moving, providing a tracer of the spacetime geometry and a probe of strong-field physics. In this paper, we construct approximate, “analytic-kludge” waveforms for such inspirals with parametrized post-Einsteinian corrections that allow for generic, model-independent deformations of the supermassive black hole background away from the Kerr metric. These approximate waveforms include all of the qualitative features of true waveforms for generic inspirals, including orbital eccentricity and relativistic precession. The deformations of the Kerr metric are modeled using a recently proposed, modified gravity bumpy metric, which parametrically deforms the Kerr spacetime while ensuring that three approximate constants of the motion remain for geodesic orbits: a conserved energy, azimuthal angular momentum and Carter constant. The deformations represent modified gravity effects and have been analytically mapped to several modified gravity black hole solutions in four dimensions. In the analytic kludge waveforms, the conservative motion is modeled by a post-Newtonian expansion of the geodesic equations in the deformed spacetimes, which in turn induce modifications to the radiation-reaction force. These analytic-kludge waveforms serve as a first step toward complete and model-independent tests of general relativity with extreme mass-ratio inspirals.

In this paper, we investigate the Ricci dark energy model with perturbations through the joint constraints of current cosmological data sets from dynamical and geometrical perspectives. We use the full cosmic microwave background information from WMAP seven-year data, the baryon acoustic oscillations from the Sloan Digital Sky Survey and the Two Degree Galaxy Redshift Survey, and type Ia supernovae from the Union2 compilation of the Supernova Cosmology Project Collaboration. A global constraint is performed by employing the Markov chain Monte Carlo method. With the best-fitting results, we show the differences of cosmic microwave background power spectra and background evolutions for the cosmological constant model and Ricci dark energy model with perturbations.

Recent results of N-body simulations have shown that current theoretical models are not able to correctly predict the amplitude of the scale-dependent halo bias induced by primordial non-Gaussianity, for models going beyond the simplest, local quadratic case. Motivated by these discrepancies, we carefully examine three theoretical approaches based on (1) the statistics of thresholded regions, (2) a peak-background split method based on separation of scales, and (3) a peak-background split method using the conditional mass function. We first demonstrate that the statistics of thresholded regions, which is shown to be equivalent at leading order to a local bias expansion, cannot explain the mass-dependent deviation between theory and N-body simulations. In the two formulations of the peak-background split on the other hand, we identify an important, but previously overlooked, correction to the non-Gaussian bias that strongly depends on halo mass. This new term is in general significant for any primordial non-Gaussianity going beyond the simplest local $f_{\mathrm{NL}}$ model. In a separate paper (to be published in PRD rapid communication), the authors compare these new theoretical predictions with N-body simulations, showing good agreement for all simulated types of non-Gaussianity.

We compute the shadows of colliding black holes using the Kastor-Traschen cosmological multiblack hole solution that is an exact solution describing the collision of maximally charged black holes with a positive cosmological constant. We find that in addition to the shadow of each black hole, an eyebrowlike structure appears as the black holes come close to each other. These features can be used as probes to find the multiblack hole system at the final stage of its merger process.