If the second Betti number $b_2$ of a Sasaki-Einstein manifold $Y^7$ does not vanish, then M-theory on ${\mathrm{AdS}}_4\times Y^7$ possesses “topological” $U(1{)}^{b_2}$ gauge symmetry. The corresponding Abelian gauge fields come from three-form fluctuations with one index in ${\mathrm{AdS}}_4$ and the other two in $Y^7$. We find black membrane solutions carrying one of these $U(1)$ charges. In the zero-temperature limit, our solutions interpolate between ${\mathrm{AdS}}_4\times Y^7$ in the UV and ${\mathrm{AdS}}_2\times {\mathbb{R}}^2\times \mathrm{\text{squashed}}{Y}^7$ in the IR. In fact, the ${\mathrm{AdS}}_2\times {\mathbb{R}}^2\times \mathrm{\text{squashed}}{Y}^7$ background is by itself a solution of the supergravity equations of motion. These solutions do not appear to preserve any supersymmetry. We search for their possible instabilities and do not find any. We also discuss the meaning of our charged membrane backgrounds in a dual quiver Chern-Simons gauge theory with a global $U(1)$ charge density. Finally, we present a simple analytic solution which has the same IR but different UV behavior. We reduce this solution to type IIA string theory, and perform T-duality to type IIB. The type IIB metric turns out to be a product of the squashed $Y^7$ and the extremal Bañados-Teitelboim-Zanelli black hole. We discuss an interpretation of this type IIB background in terms of the ($1+1$)-dimensional conformal field theory on $D3$-branes partially wrapped over the squashed $Y^7$.

We study the QCD phase structure in the three-flavor Nambu–Jona-Lasinio model, incorporating the interplay between the chiral and diquark condensates induced by the axial anomaly. We demonstrate that for an appropriate range of parameters of the model, the interplay leads to the low temperature critical point in the phase structure predicted by a previous Ginzburg-Landau analysis. We also show that a Bose-Einstein condensate (BEC) of diquark molecules emerges in the intermediate density region, and as a result, a BEC-BCS crossover is realized with increasing quark chemical potential.

We investigate spherically symmetric perfect-fluid spacetimes and discuss the existence and stability of a dividing shell separating expanding and collapsing regions. We perform a $3+1$ splitting and obtain gauge invariant conditions relating the intrinsic spatial curvature of the shells to the Misner-Sharp mass and to a function of the pressure that we introduce and that generalizes the Tolman-Oppenheimer-Volkoff equilibrium condition. We find that surfaces fulfilling those two conditions fit, locally, the requirements of a dividing shell, and we argue that cosmological initial conditions should allow its global validity. We analyze the particular cases of the Lemaître-Tolman-Bondi dust models with a cosmological constant as an example of a cold dark matter model with a cosmological constant ($\Lambda$-CDM model) and its generalization to contain a central perfect-fluid core. These models provide simple but physically interesting illustrations of our results.

We investigate cosmological constraints on an energy density contribution of elastic dark matter self-interactions characterized by the mass of the exchange particle $m_{\mathrm{SI}}$ and coupling constant ${\alpha }_{\mathrm{SI}}$. Because of the expansion behavior in a Robertson-Walker metric we investigate self-interacting dark matter that is warm in the case of thermal relics. The scaling behavior of dark matter self-interaction energy density (${\varrho }_{\mathrm{SI}}\propto a^{-6}$) shows that it can be the dominant contribution (only) in the very early universe. Thus its impact on primordial nucleosynthesis is used to restrict the interaction strength $m_{\mathrm{SI}}/\sqrt{{\alpha }_{\mathrm{SI}}}$, which we find to be at least as strong as the strong interaction. Furthermore we explore dark matter decoupling in a self-interaction dominated universe, which is done for the self-interacting warm dark matter as well as for collisionless cold dark matter in a two component scenario. We find that strong dark matter self-interactions do not contradict superweak inelastic interactions between self-interacting dark matter and baryonic matter (${\sigma }_{\mathrm{A}}^{\mathrm{SIDM}}\ll {\sigma }_{\mathrm{weak}}$) and that the natural scale of collisionless cold dark matter decoupling exceeds the weak scale (${\sigma }_{\mathrm{A}}^{\mathrm{CDM}}>{\sigma }_{\mathrm{weak}}$) and depends linearly on the particle mass. Finally structure formation analysis reveals a linear growing solution during self-interaction domination ($\delta \propto a$); however, only noncosmological scales are enhanced.

We use present cosmological data from the cosmic microwave background, large-scale structure and deuterium at high redshifts to constrain supersymmetric $F$- and $D$-term hybrid inflation scenarios including possible contributions to the CMB anisotropies from cosmic strings. Using two different realizations of the cosmic string spectrum, we find that the minimal version of the $D$-term model is ruled out at high significance. $F$-term models are also in tension with the data. We also discuss possible nonminimal variants of the models.

We discuss the kinematics of the particles that make up a Reggeon in field theory, using the terminology of the soft collinear effective theory (SCET). Reggeization sums a series of strongly ordered collinear emissions resulting in an overall Reggeon exchange that falls in the Glauber or Coulomb kinematic region. This is an extremely multiscale problem and appears to fall outside of the usual organizing scheme of SCET.

We construct and solve the Dyson-Schwinger equation of a quark propagator with a parameterized metric, which connects the Euclidean metric with the Minkowskian one. We show, in some models, that the Minkowskian vacuum is different from the Euclidean vacuum. The usual analytic continuation of the Green function does not make sense in these cases. While with the algorithm we proposed and the quark-gluon vertex ansätz which preserves the Ward-Takahashi identity, the vacuum keeps being unchanged in the evolution of the metric. In this case, analytic continuation becomes meaningful and can be fully carried out.

Particle production by a semitransparent mirror accelerating on trajectories which simulate the Hawking effect was recently discussed in [3]. This author points out that some results in [1] are incorrect. We show here that, contrary to statements therein, the main results and conclusions of the last paper remain valid, only Eq. (41) there and some particular implication are not. The misunderstanding actually comes from comparing two very different parameter regions, and from the fact that, in our work, the word statistics was used in an unusual way related to the sign of the $\beta$-Bogoliubov coefficient, and not with its ordinary meaning, connected with the number of particles emitted per mode.

The Laser Interferometer Space Antenna’s (LISA’s) observation of supermassive binary black holes (SMBBH) could provide a new tool for precision cosmography. Inclusion of subdominant signal harmonics in the inspiral signal allows for high-accuracy sky localization, dramatically improving the chances of finding the host galaxy and obtaining its redshift. A SMBBH merger can potentially have component masses from a wide range (${10}^5–{10}^8{M}_{\odot }$) over which parameter accuracies vary considerably. We perform an in-depth study in order to understand (i) what fraction of possible SMBBH mergers allow for sky localization, depending on the parameters of the source, and (ii) how accurately $w$ can be measured when the host galaxy can be identified. We also investigate how accuracies on all parameters improve when a knowledge of the sky position can be folded into the estimation of errors. We find that $w$ can be measured to within a few percent in most cases, if the only error in measuring the luminosity distance is due to LISA’s instrumental noise and the confusion background from Galactic binaries. However, weak lensing-induced errors will severely degrade the accuracy with which $w$ can be obtained, emphasizing that methods to mitigate weak lensing effects would be required to take advantage of LISA’s full potential.

In the context of metric perturbation theory for nonspinning black holes, extreme mass ratio binary systems are described by distributionally forced master wave equations. Numerical solution of a master wave equation as an initial boundary value problem requires initial data. However, because the correct initial data for generic-orbit systems is unknown, specification of trivial initial data is a common choice, despite being inconsistent and resulting in a solution which is initially discontinuous in time. As is well known, this choice leads to a burst of junk radiation which eventually propagates off the computational domain. We observe another potential consequence of trivial initial data: development of a persistent spurious solution, here referred to as the Jost junk solution, which contaminates the physical solution for long times. This work studies the influence of both types of junk on metric perturbations, waveforms, and self-force measurements, and it demonstrates that smooth modified source terms mollify the Jost solution and reduce junk radiation. Our concluding section discusses the applicability of these observations to other numerical schemes and techniques used to solve distributionally forced master wave equations.

We make use of the universally valid stress-energy conservation law to study the motion of various branelike extended objects in a generic brane-world. Without specifying any particular action, we are able to derive the world-sheet equations that govern the dynamics of brane-world test branes. In particular, the brane-world test particles are shown to follow geodesics with respect to the brane-world induced metric. At the same time, the presence of extended objects is shown to influence the brane-world geometry. It is demonstrated that codimension-1 branes necessarily violate the brane-world smooth structure, while lower-dimensional branes violate the very continuity. In particular, the truly zero-size massive particles are shown not to exist in a continuous brane-world. As an example, static, axially symmetric membrane-world in $4d$ Minkowski background is analyzed.

The electric field of the Čerenkov radio pulse produced by a single charged particle track in a dielectric medium is derived from first principles. An algorithm is developed to obtain the pulse in the time domain for numerical calculations. The algorithm is implemented in a Monte Carlo simulation of electromagnetic showers in dense media (specifically designed for coherent radio emission applications) as might be induced by interactions of ultrahigh energy neutrinos. The coherent Čerenkov radio emission produced by such showers is obtained simultaneously both in the time and frequency domains. A consistency check performed by Fourier transforming the pulse in time and comparing it to the frequency spectrum obtained directly in the simulations yields, as expected, fully consistent results. The reversal of the time structure inside the Čerenkov cone and the signs of the corresponding pulses are addressed in detail. The results, besides testing algorithms used for reference calculations in the frequency domain, shed new light into the properties of the radio pulse in the time domain. The shape of the pulse in the time domain is directly related to the depth development of the excess charge in the shower and its width to the observation angle with respect to the Čerenkov direction. This information can be of great practical importance for interpreting actual data.

Molecular flow gas damping of mechanical motion in confined geometries, and its associated noise, is important in a variety of fields, including precision measurement, gravitational wave detection, and microelectromechanical systems devices. We used two torsion balance instruments to measure the strength and distance-dependence of “squeeze film” damping. Measured quality factors derived from free decay of oscillation are consistent with gas particle superdiffusion in Lévy walks and inconsistent with those expected from traditional Gaussian random walk particle motion. The distance-dependence of squeeze film damping observed in our experiments is in agreement with a parameter-free Monte Carlo simulation. The squeeze film damping of the motion of a plate suspended a distance $d$ away from a parallel surface scales with a fractional power between $d^{-1}$ and $d^{-2}$.

We outline the expected constraints on non-Gaussianity from the cosmic microwave background with current and future experiments, focusing on both the third ($f_{\mathrm{NL}}$) and fourth-order ($g_{\mathrm{NL}}$ and ${\tau }_{\mathrm{NL}}$) amplitudes of the local configuration or non-Gaussianity. The experimental focus is the skewness (two-to-one) and kurtosis (two-to-two and three-to-one) power spectra from weighted maps. In addition to a measurement of ${\tau }_{\mathrm{NL}}$ and $g_{\mathrm{NL}}$ with WMAP 5-year data, our study provides the first forecasts for future constraints on $g_{\mathrm{NL}}$. We describe how these statistics can be corrected for the mask and cut-sky through a window function, bypassing the need to compute linear terms that were introduced for the previous-generation non-Gaussianity statistics, such as the skewness estimator. We discus the ratio $A_{\mathrm{NL}}={\tau }_{\mathrm{NL}}/(6f_{\mathrm{NL}}/5{)}^2$ as an additional test of single-field inflationary models and discuss the physical significance of each statistic. Using these estimators with WMAP 5-Year $\mathrm{V}+\mathrm{W}$-band data out to $l_{\max }=600$ we constrain the cubic order non-Gaussianity parameters ${\tau }_{\mathrm{NL}}$, and $g_{\mathrm{NL}}$ and find $-7.4<g_{\mathrm{NL}}/{10}^5<8.2$ and $-0.6<{\tau }_{\mathrm{NL}}/{10}^4<3.3$ improving the previous COBE-based limit on ${\tau }_{\mathrm{NL}}<{10}^8$ nearly 4 orders of magnitude with WMAP.

The recently proposed dark left-right gauge model, with $Z^{\prime }$ and $W_R^{\pm }$ bosons at the TeV scale, is shown to have a simple supersymmetric extension which is unifiable. Its one-loop gauge-coupling renormalization-group equations are shown to have identical solutions to those of the minimal supersymmetric standard model. It also has a rich dark sector, with at least three stable particles.

In this paper, we study the recent excess of low energy events observed by the CoGeNT Collaboration, and discuss the possibility that these events originate from the elastic scattering of a light ($m_{\mathrm{DM}}\sim 5–10\mathrm{GeV}$) weakly interacting massive particle (WIMP). We find that such a dark matter candidate may also be capable of generating the annual modulation reported by DAMA, without conflicting with the null results from other experiments, such as XENON10. The regions implied by CoGeNT and DAMA are also near those required to produce the two observed CDMS events. A dark matter interpretation of the CoGeNT and DAMA observations favors a region of parameter space that is especially attractive within the context of asymmetric dark matter models. In such models, the cosmological dark matter density arises from the baryon asymmetry of the Universe, naturally leading to the expectation that $m_{\mathrm{DM}}\sim 1–10\mathrm{GeV}$. We also discuss neutralino dark matter from extended supersymmetric frameworks, such as the next-to-minimal supersymmetric standard model. Lastly, we explore the implications of such a dark matter candidate for indirect searches, and find very encouraging prospects for experiments attempting to detect neutrino or gamma ray annihilation products.

By exploring specific helicity states in quark-gluon scattering at tree level we show explicitly that the full $t$-channel pole can be described exactly as a contraction of two local currents. In the four cases of helicity assignment where a channel exists also for $qQ$-scattering, $qg$-scattering is described exactly by this $t$-channel pole. Only in two of the four remaining helicity assignments is there a contribution from $u$- and $s$-channel poles. We extract a gauge-invariant definition for the $t$-channel current generated by the scattering of a gluon and offer an interpretation of the form.

Long-distance contributions to the $D^0\mathrm{\text{−}}{\overline{D}}^0$ mixing parameters $x$ and $y$ are evaluated using latest data on hadronic $D^0$ decays. In particular, we take on two-body $D\to PP$ and $VP$ decays to evaluate the contributions of two-body intermediate states because they account for $\sim 50\%$ of hadronic $D^0$ decays. Use of the diagrammatic approach has been made to estimate yet-observed decay modes. We find that $y$ is of order a few $\times {10}^{-3}$ and $x$ of order ${10}^{-3}$ from hadronic $PP$ and $VP$ modes. These are in good agreement with the latest direct measurement of $D^0\mathrm{\text{−}}{\overline{D}}^0$ mixing parameters using the $D^0\to K_S{\pi }^{+}{\pi }^{-}$ and $K_S{K}^{+}{K}^{-}$ decays by BABAR. We estimate the contribution to $y$ from the $VV$ modes using the factorization model and comment on the single-particle resonance effects and contributions from other two-body modes involving even-parity states.

The definition of a quark as heavy requires a comparison of its mass with the nonperturbative chiral symmetry breaking scale which is about 1 GeV (${\Lambda }_{\chi }\sim 1\mathrm{GeV}$) or with the scale ${\Lambda }_{\mathrm{QCD}}\sim 0.2\mathrm{GeV}$ that characterizes the distinction between perturbative and nonperturbative QCD. For quark masses significantly larger than these scales, nonperturbative dressing effects, or equivalently nonperturbative self-energy contributions, and relativistic effects are believed to be less important for physical observables. We explore the concept of a constituent mass for heavy quarks in the Dyson-Schwinger equations formalism, for light-heavy and heavy-heavy quark mesons by studying their masses and electroweak decay constants.

We predict the differential cross sections for production of the $X(3872)$ at the Tevatron and the Large Hadron Collider from both prompt QCD mechanisms and from decays of $b$ hadrons. The prompt cross section is calculated using the nonrelativistic QCD (NRQCD) factorization formula. Simplifying assumptions are used to reduce the nonperturbative parameters to a single nonrelativistic QCD matrix element that is determined from an estimate of the prompt cross section at the Tevatron. For $X(3872)$ with transverse momenta greater than about 4 GeV, the predicted cross section is insensitive to the simplifying assumptions. We also discuss critically a recent analysis that concluded that the prompt production rate at the Tevatron is too large by orders of magnitude for the $X(3872)$ to be a weakly bound charm-meson molecule. We point out that if charm-meson rescattering is properly taken into account, the upper bound is increased by orders of magnitude and is compatible with the observed production rate at the Tevatron.