The spin and quadrupole moment of the supermassive black hole at the Galactic center can in principle be measured via astrometric monitoring of stars orbiting at milliparsec distances, allowing tests of general relativistic “no-hair”theorems [23]. One complicating factor is the presence of perturbations from other stars, which may induce orbital precession of the same order of magnitude as that due to general relativistic effects. The expected number of stars in this region is small enough that full $N$-body simulations can be carried out. We present the results of a comprehensive set of such simulations, which include a post-Newtonian treatment of spin-orbit effects. A number of possible models for the distribution of stars and stellar remnants are considered. We find that stellar perturbations are likely to obscure the signal due to frame dragging for stars beyond $\sim 0.5\mathrm{mpc}$ from the black hole, while measurement of the quadrupole moment is likely to require observation of stars inside $\sim 0.2\mathrm{mpc}$. A high fraction of stellar remnants, e.g. $10{\mathcal{M}}_{\odot }$ black holes, in this region would make tests of general relativity problematic at all radii. We discuss the possibility of separating the effects of stellar perturbations from those due to general relativity.

The Casimir force has been computed exactly for only a few simple geometries, such as infinite plates, cylinders, and spheres. We show that a parabolic cylinder, for which analytic solutions to the Helmholtz equation are available, is another case where such a calculation is possible. We compute the interaction energy of a parabolic cylinder and an infinite plate (both perfect mirrors), as a function of their separation and inclination, $H$ and $\theta$, and the cylinder’s parabolic radius $R$. As $H/R\to 0$, the proximity force approximation becomes exact. The opposite limit of $R/H\to 0$ corresponds to a semi-infinite plate, where the effects of edge and inclination can be probed.

The strong coupling constants between light vector mesons and octet-decuplet baryons are calculated in framework of the light cone QCD sum rules, taking into account $SU(3)$ flavor symmetry breaking effects. It is shown that all strong coupling constants can be represented in terms of a single universal function. Size of the $SU(3)$ symmetry breaking effects are estimated.

New models have recently been proposed in which a second Higgs doublet couples only to the lepton doublets and right-handed neutrinos, yielding Dirac neutrino masses. The vacuum value of this second “nu-Higgs” doublet is made very small by means of a very softly-broken $Z_2$ or $U(1)$ symmetry. The latter is technically natural and avoids fine-tuning and very light scalars. We consider a supersymmetric version of this model, in which two additional doublets are added to the minimal supersymmetric standard model (MSSM). If kinematically allowed, the decay of the heavy MSSM scalar into charged nu-Higgs scalars will yield dilepton events which can be separated from the W-pair background. In addition, the nu-Higgsinos can lead to very dramatic tetralepton, pentalepton, and hexalepton events which have negligible background and can be detected at the LHC and the Tevatron.

We provide a scenario where naturally small and calculable neutrino masses arise from a supersymmetry-breaking renormalization-group-induced vacuum expectation value. The construction consists of an extended version of the next-to-minimal supersymmetric standard model and the mechanism is illustrated for a universal choice of the soft supersymmetry-breaking parameters. The lightest supersymmetric particle can be an isosinglet scalar neutrino state, potentially viable as WIMP dark matter through its Higgs new boson coupling. The scenario leads to a plethora of new phenomenological implications at accelerators including the Large Hadron Collider.

In this paper we implement scale anisotropic transformations between space and time in classical mechanics. The resulting system is consistent with the dispersion relation of Hořava gravity [P. Hořava, Phys. Rev. D 79, 084008 (2009)]. Also, we show that our model is a generalization of the conformal mechanics of Alfaro, Fubini, and Furlan. For an arbitrary dynamical exponent we construct the dynamical symmetries that correspond to the Schrödinger algebra. Furthermore, we obtain the Boltzmann distribution for a gas of free particles compatible with anisotropic scaling transformations and compare our result with the corresponding thermodynamics of the recent anisotropic black branes proposed in the literature.

We argue that, when working with the appropriate set of thermodynamical variables, the Bekenstein-Hawking law still holds for asymptotically flat black objects with conical singularities. The mass energy which enters the first law of thermodynamics does not, however, coincide with the Arnowitt-Deser-Misner mass; it differs from the latter by the energy associated with the conical singularity, as seen by an asymptotic, static observer. These statements are supported by a number of examples: the Bach-Weyl (double-Schwarzschild) solution, its dihole generalization in Einstein-Maxwell theory and the five-dimensional static black ring.

We consider recently proposed higher-order gravity models where the action is built from the Einstein-Hilbert action plus a function $f(G)$ of the Gauss-Bonnet invariant. The models were previously shown to pass physical acceptability conditions as well as solar system tests. In this paper, we compare the models to combined data sets of supernovae, baryon acoustic oscillations, and constraints from the CMB surface of last scattering. We find that the models provide fits to the data that are close to those of the lambda cold dark matter concordance model. The results provide a pool of higher-order gravity models that pass these tests and need to be compared to constraints from large scale structure and full CMB analysis.

A scalar-tensor theory of gravity can be made not only to account for the current cosmic acceleration, but also to satisfy solar-system and laboratory constraints, by introducing a nonlinear derivative interaction for the scalar field. Such an additional scalar degree of freedom is called “Galileon.” The basic idea is inspired by the Dvali-Gabadadze-Porrati braneworld, but one can construct a ghost-free model that admits a self-accelerating solution. We perform a fully relativistic analysis of linear perturbations in Galileon cosmology. Although the Galileon model can mimic the background evolution of standard $\Lambda \mathrm{CDM}$ cosmology, the behavior of perturbation is quite different. It is shown that there exists a superhorizon growing mode in the metric and Galileon perturbations at early times, suggesting that the background is unstable. A fine-tuning of the initial condition for the Galileon fluctuation is thus required in order to promote a desirable evolution of perturbations at early times. Assuming the safe initial condition, we then compute the late-time evolution of perturbations and discuss observational implications in Galileon cosmology. In particular, we find anticorrelations in the cross correlation of the integrated Sachs-Wolfe effect and large scale structure, similar to the normal branch of the Dvali-Gabadadze-Porrati model.

Distortions in the primordial cosmic microwave background (CMB) along the line of sight can be modeled and described using 11 fields. These distortion fields correspond to various cosmological signals such as weak gravitational lensing of the CMB by a large-scale structure, screening from patchy reionization, and rotation of the plane of polarization due to magnetic fields or parity violating physics. Various instrumental systematics such as gain fluctuations, pixel rotation, differential gain, pointing, and differential ellipticity are also described by the same distortion model. All these distortions produce a $B$ mode that contaminates the primordial tensor $B$-modes signal. In this paper we show that, apart from generating $B$ modes, each distortion uniquely couples different modes (${\mathit{l}}_1\ne {\mathit{l}}_2$) of the CMB anisotropies, generating $⟨EB⟩$ correlations which for the primordial CMB are zero. We describe and implement unbiased minimum variance quadratic estimators which using the off-diagonal correlations in the CMB can extract the map of distortions. We perform Monte Carlo simulations to characterize the estimators and illustrate the level of distortions that can be detected with current and future experiments. The estimators can be used to look for cosmological signals, or to check for any residual systematics in the data. As a specific example of primordial tensor $B$-mode diagnostics, we compare the level of minimum detectable distortions using our method with maximum allowed distortion level for the $B$-modes detection. We show that for any experiment, the distortions will be detected at high significance using correlations before they would show up as spurious $B$ modes in the power spectrum. In other words, if $B$ modes were to be detected, the presence of any nonprimordial contribution could be checked and removed using the off-diagonal correlations in the CMB.

We study the slow-roll inflation models, where the inflaton slow-rolls along a trajectory whose orthogonal directions are lifted by potentials with masses of order the Hubble parameter. In these models large non-Gaussianities can be generated through the transformation from the isocurvature modes to the curvature mode, once the inflaton trajectory turns. We find large bispectra with a one-parameter family of novel shapes, interpolating between the equilateral and local shape. According to the in-in formalism, the shapes of these non-Gaussianities are different from a simple projection from the isocurvature non-Gaussian correlation functions.

We consider the effect of nonstandard neutrino interactions (NSI, for short) on the propagation of neutrinos through the supernova (SN) envelope within a three-neutrino framework and taking into account the presence of a neutrino background. We find that for given NSI parameters, with strength generically denoted by ${\epsilon }_{ij}$, neutrino evolution exhibits a significant time dependence. For $|{\epsilon }_{\tau \tau }|\gtrsim {10}^{-3}$ the neutrino survival probability may become sensitive to the ${\vartheta }_{23}$ octant and the sign of ${\epsilon }_{\tau \tau }$. In particular, if ${\epsilon }_{\tau \tau }\gtrsim {10}^{-2}$ an internal $I$-resonance may arise independently of the matter density. For typical values found in SN simulations this takes place in the same dense-neutrino region above the neutrinosphere where collective effects occur, in particular, during the synchronization regime. This resonance may lead to an exchange of the neutrino fluxes entering the bipolar regime. The main consequences are (i) bipolar conversion taking place for normal neutrino mass hierarchy and (ii) a transformation of the flux of low-energy ${\nu }_e$, instead of the usual spectral swap.

The detection and estimation of gravitational wave signals belonging to a parameterized family of waveforms requires, in general, the numerical maximization of a data-dependent function of the signal parameters. Because of noise in the data, the function to be maximized is often highly multimodal with numerous local maxima. Searching for the global maximum then becomes computationally expensive, which in turn can limit the scientific scope of the search. Stochastic optimization is one possible approach to reducing computational costs in such applications. We report results from a first investigation of the particle swarm optimization method in this context. The method is applied to a test bed motivated by the problem of detection and estimation of a binary inspiral signal. Our results show that particle swarm optimization works well in the presence of high multimodality, making it a viable candidate method for further applications in gravitational wave data analysis.

We present projected constraints on modified gravity models from the observational technique known as 21 cm intensity mapping, where cosmic structure is detected without resolving individual galaxies. The resulting map is sensitive to both baryon acoustic oscillations and weak lensing, two of the most powerful cosmological probes. It is found that a $200\mathrm{m}\times 200\mathrm{m}$ cylindrical telescope, sensitive out to $z=2.5$, would be able to distinguish Dvali, Gabadadze, and Porrati from most dark energy models, and constrain the Hu and Sawicki $f(R)$ model to $|f_{R0}|<9\times {10}^{-6}$ at 95% confidence. The latter constraint makes extensive use of the lensing spectrum in the nonlinear regime. These results show that 21 cm intensity mapping is not only sensitive to modifications of the standard model’s expansion history, but also to structure growth. This makes intensity mapping a powerful and economical technique, achievable on much shorter time scales than optical experiments that would probe the same era.

We consider two optimally mixed neutralino dark matter models, based on nonuniversal gaugino masses, which were recently proposed by us to achieve WMAP compatible relic density over a large part of the minimal supersymmetric standard model parameter space. We compare the resulting predictions for the spin-independent dark matter scattering cross section with the recent CDMS II data, assuming the possibility of the two reported candidate events being signal events. For one model the predicted cross section agrees with the putative signal over a small part of the parameter space, while for the other the agreement holds over the entire WMAP compatible parameter space of the model.

Unitarity, a powerful constraint on new physics, has not always been properly accounted for in the context of hidden sectors. Feng, Rajaraman, and Tu have suggested that large (pb to nb) multiphoton or multilepton signals could be generated at the LHC through the three-point functions of a conformally invariant hidden sector (an “unparticle” sector). Because of the conformal invariance, the kinematic distributions are calculable. However, the cross sections for many such processes grow rapidly with energy, and at some high scale, to preserve unitarity, conformal invariance must break down. Requiring that conformal invariance not be broken, and that no signals be already observed at the Tevatron, we obtain a strong unitarity bound on multiphoton events at the (10 TeV) LHC. For the model of Feng et al., even with extremely conservative assumptions, cross sections must be below 25 fb, and for operator dimension near 2, well below 1 fb. In more general models, four-photon signals could still reach cross sections of a few pb, though bounds below 200 fb are more typical. Our methods apply to a wide variety of other processes and settings.

We report stronger constraints on the parameters of Yukawa-type corrections to Newtonian gravity from measurements of the lateral Casimir force between sinusoidally corrugated surfaces of a sphere and a plate. In the interaction range from 1.6 to 14 nm the strengthening of previously known high confidence constraints up to a factor of $2.4\times {10}^7$ is achieved using these measurements. It is shown that the replacement of a plane plate with a corrugated one in the measurements of the normal Casimir force by means of an atomic force microscope would result in the strengthening of respective high confidence constraints on the Yukawa-type interaction by a factor of $1.1\times {10}^{12}$. The use of a corrugated plate instead of a plane plate in the experiment by means of a micromachined oscillator also leads to strengthening of the obtained constraints. We further obtain constraints on the parameters of Yukawa-type interaction from the data of experiments measuring the gradient of the Casimir pressure between two parallel plates and the gradient of the Casimir-Polder force between an atom and a plate. The obtained results are compared with the previously known constraints. The possibilities of how to further strengthen the constraints on non-Newtonian gravity are discussed.

We study the scaling behavior and finite (physical) volume effects as well as the Gribov copy dependence of the $SU(2)$ Landau gauge gluon propagator on the lattice. Our physical lattice sizes range from $(3.0\mathrm{fm}{)}^4$ to $(7.3\mathrm{fm}{)}^4$. Considering lattices with decreasing lattice spacing but fixed physical volume we confirm (nonperturbative) multiplicative renormalizability and the approach to the continuum limit for the renormalized gluon propagator $D_{\mathrm{ren}}(p)$ at momenta $|p|\gtrsim 0.6\mathrm{GeV}$. The finite-volume effects and Gribov copy influence turn out small in this region. On the contrary, in the deeper infrared we found the Gribov copy influence strong and finite-volume effects, which still require special attention. The gluon propagator does not seem to be consistent with a simple polelike behavior $\sim (p^2+m_g^2{)}^{-1}$ for momenta $|p|\lesssim 0.6\mathrm{GeV}$. Instead, a Gaussian-type fit works very well in this region. From its width—for a physical volume $(5.0\mathrm{fm}{)}^4$- we estimate a corresponding infrared (mass) scale to be $m_{\mathrm{IR}}\sim 0.7\mathrm{GeV}$.

We propose to describe the time evolution of quasistationary fluctuations near QCD critical point by a system of stochastic Boltzmann-Langevin-Vlasov-type equations. We derive the equations and study the system analytically in the linearized regime. Known results for equilibrium stationary fluctuations as well as the critical scaling of diffusion coefficient are reproduced. We apply the approach to the long-standing question of the fate of the critical point fluctuations during the hadronic rescattering stage of the heavy-ion collision after chemical freeze-out. We find that if conserved particle number fluctuations survive the rescattering, so do, under a certain additional condition, the fluctuations of nonconserved quantities, such as mean transverse momentum. We derive a simple analytical formula for the magnitude of this memory effect.

Conventional methods to determine nonperturbative parameters in QCD, such as the different variants of QCD sum rules or the minimal hadronic approximation, combine a certain degree of matching to QCD with inputs from hadronic parameters. The latter introduce systematic errors difficult to quantify. In this paper, I will apply a method based on rational approximant theory where matching is maximized and no hadronic inputs are used, thereby leading to simple analytical relations between high- and low-energy parameters. I will be mostly interested in the phenomenological applications to the ${\Pi }_{LR}$ and ${\Pi }_{VT}$ correlators, with special emphasis on quantities like the $d=6$ and $d=8$ vacuum condensates in ${\Pi }_{LR}$ or the quark condensate magnetic susceptibility ${\chi }_0$.