We apply complex Langevin dynamics to chiral random matrix theory at nonzero chemical potential. At large quark mass, the simulations agree with the analytical results while incorrect convergence is found for small quark masses. The region of quark masses for which the complex Langevin dynamics converges incorrectly is identified as the region where the fermion determinant frequently traces out a path surrounding the origin of the complex plane during the Langevin flow. This links the incorrect convergence to an ambiguity in the Langevin force due to the presence of the logarithm of the fermion determinant in the action.

We consider the collider signals of spin-one resonances present in full-hierarchy quiver theories of electroweak symmetry breaking. These four-dimensional theories result from the deconstruction of warped extra dimensional models and have very distinct phenomenological features when the number of sites is small. We study a class of generic scenarios in these theories where the color gauge group, as well as the electroweak sector, propagates in the quiver diagram. These scenarios correspond to various specific models of electroweak symmetry breaking and fermion masses. We focus on the minimum resonant content and its main features: the presence of heavy and narrow spin-one resonances. We derive bounds from the LHC data on the color-octet and color-singlet excited gauge bosons from their decays to jets and top pairs, and show their dependence on the number of sites in the quiver. We also compare them with the bounds derived from flavor violation.

Using experimental spectral data for hadronic $\tau$ decays from the OPAL experiment, supplemented by a phenomenologically successful parametrization for the high-$s$ region not covered by the data, we construct a physically constrained model of the isospin-one vector-channel polarization function. Having such a model as a function of Euclidean momentum $Q^2$ allows us to explore the systematic error associated with fits to the $Q^2$ dependence of lattice data for the hadronic electromagnetic current polarization function which have been used in attempts to compute the leading order hadronic contribution, $a_{\mu }^{\mathrm{HLO}}$, to the muon anomalous magnetic moment. In contrast to recent claims made in the literature, we find that a final error in this quantity of the order of a few percent does not appear possible with current lattice data, given the present lack of precision in the determination of the vacuum polarization at low $Q^2$. We also find that fits to the vacuum polarization using fit functions based on vector meson dominance are unreliable, in that the fit error on $a_{\mu }^{\mathrm{HLO}}$ is typically much smaller than the difference between the value obtained from the fit and the exact model value. The use of a sequence of Padé approximants known to converge to the true vacuum polarization appears to represent a more promising approach.

We have calculated continuum-limit step scaling functions of bilinear and four-fermion operators renormalized in a Rome-Southampton scheme using various smearing prescriptions for the gauge field. Also, for the first time, we have calculated nonperturbative anomalous dimensions of operators renormalized in a Rome-Southampton scheme. The effect of such smearing first enters connected fermionic correlation functions via radiative corrections. We use off-shell renormalization as a probe, and observe that the upper edge of the Rome-Southampton window is reduced by link smearing. This can be interpreted as arising due to the fermions decoupling from the high-momentum gluons and we observe that the running of operators with the scale at large lattice momenta shows enhanced lattice artifacts. We find that the effect is greater for HEX smearing than for Stout smearing, but that in both cases additional care must be taken when using off-shell renormalization with smeared gauge fields compared to thin-link simulations.

We present a detailed phenomenological study of charged-current-mediated deep-inelastic scattering off longitudinally polarized nucleons at a future electron-ion collider. A new version of the event generator package Djangoh, extended by capabilities to handle processes with polarized nucleons, is introduced and used to simulate charged current deep-inelastic scattering including QED, QCD, and electroweak radiative effects. We carefully explore the range of validity and the accuracy of the Jacquet-Blondel method to reconstruct the relevant kinematic variables from the measured hadronic final state in charged current events, assuming realistic detector performance parameters. Finally, we estimate the impact of the simulated charged current single-spin asymmetries on determinations of helicity parton distributions in the context of a global QCD analysis at next-to-leading order accuracy.

We explore the impact of nonstandard interactions at source and detector on the interpretation of reactor electron neutrino disappearance experiments with short- and medium-baseline designs. We use the constraints from the recent results from short-baseline experiments and generalize current estimates of medium-baseline event rates to include charged current interactions at source and detector with standard Lorentz structure but with nonstandard flavor structure. We find that the average spectrum of observed events at a baseline of 50 km, in the middle of the currently favored region, provides a probe of new interactions. We show that an improvement in sensitivity to nonstandard interactions is possible if combined with improved precision of input mixing parameters in independent experiments, despite ambiguity in interpretation of medium-baseline data. We show that nonstandard interactions can enhance or suppress the sensitivity of experiments to the mass hierarchy, depending on the phases of the parameters and the $CP$-violating phase in the standard three-neutrino mixing picture.

The problem of deforming geometries is particularly important in the context of constructing new exact solutions of Einstein’s equation. This issue often appears when extensions of the general relativity are treated, for instance in brane world scenarios. In this paper we investigate spacetimes in which the energy-momentum tensor obeys a linear constraint. Extensions of the usual vacuum and electrovacuum solutions of general relativity are derived and an exact solution is presented. The classes of geometries obtained include a wide variety of compact objects, among them black holes and wormholes. The general metric derived in this work generalizes several solutions already published in the literature. Perturbations around the exact solution are also considered.

Bogomol’nyi-Prasad-Sommerfield monopoles on ${\mathbb{R}}^2\times S^1$ correspond, via the generalized Nahm transform, to certain solutions of the Hitchin equations on the cylinder $\mathbb{R}\times S^1$. The moduli space $\mathcal{M}$ of two monopoles with their center of mass fixed is a four-dimensional manifold with a natural hyperkähler metric, and its geodesics correspond to slow-motion monopole scattering. The purpose of this paper is to study the geometry of $\mathcal{M}$ in terms of the Nahm-Hitchin data, i.e., in terms of structures on $\mathbb{R}\times S^1$. In particular, we identify the moduli, derive the asymptotic metric on $\mathcal{M}$, and discuss several geodesic surfaces and geodesics on $\mathcal{M}$. The latter include novel examples of monopole dynamics.

To obtain the end-point evolution of the so-called black hole laser instability, we study the set of stationary solutions of the Gross-Pitaevskii equation for piecewise constant potentials which admit a homogeneous solution with a supersonic flow in the central region between two discontinuities. When the distance between them is larger than a critical value, we find that the homogeneous solution is unstable, and we identify the lowest energy state. We show that it can be viewed as determining the saturated value of the first (nodeless) complex frequency mode which drives the instability. We also classify the set of stationary solutions and establish their relation both with the set of complex frequency modes and with known soliton solutions. Finally, we adopt a procedure à la Pitaevski-Baym-Pethick to construct the effective functional which governs the transition from the homogeneous to nonhomogeneous solutions.

A model in which pointlike defects are randomly embedded in Minkowski spacetime is considered. The distribution of spacetime defects is constructed to be Lorentz invariant. Since it is based on a sprinkling process, it does not introduce a preferred reference frame. A field-theoretic action for the photon and a fermion is set up, in which the photon is assumed not to couple to the defects directly, but via a scalar field. We are interested in signs for Lorentz violation caused by the spacetime defects, which are expected to reveal themselves in the photon sector. A modification of the photon dispersion relation may result as a quantum effect, and we compute it at leading order perturbation theory. The outcome of the calculation is that the photon dispersion law remains conventional, if the defect distribution is dense, homogeneous, and isotropic. This result sheds some new light on Lorentz violation in the framework of a small-scale structure of spacetime. It shows that Lorentz invariance can be preserved even in the presence of a spacetime structure that is supposed to emerge at the Planck scale. This conclusion has already been drawn on general grounds in other publications, where the current paper delivers a demonstration by a direct computation in a simple model.

The entropy of a Bañados, Teitelboim, and Zanelli black hole in topologically massive gravity had been given with the form inconsistent with the Bekenstein-Hawking entropy. In the paper, we provide a consistent statistical interpretation for the entropy, and confirm it to be thermodynamic entropy by preserving the first and second laws. As a novel extension, the logarithmic correction to the black hole entropy is also discussed.

Massive gravity in three dimensions accepts several different formulations. Recently, the three-dimensional bigravity de Rham–Gabadadze–Tolley (dRGT) model in first-order form, Zwei-Dreibein gravity, was considered by Bergshoeff et al., and it was argued that the Boulware-Deser mode is killed by extra constraints. We revisit this assertion and conclude that there are sectors on the space of initial conditions, or subsets of the most general such model, where this mode is absent. But, generically, the theory does carry 3 degrees of freedom, and thus the Boulware-Deser mode is still active. Our results also sheds light on the equivalence between metric and vierbein formulations of the dRGT model.

We calculate analytical gravitational waveforms in the time and frequency domain for precessing quasicircular binaries with spins of arbitrary magnitude, but nearly aligned with the orbital angular momentum. We first derive an analytical solution to the precession equations by expanding in the misalignment angle and using multiple scale analysis to separate time scales. We then use uniform asymptotic expansions to analytically Fourier transform the time-domain waveform, thus extending the stationary-phase approximation, which fails when precession is present. The resulting frequency-domain waveform family has a high overlap with numerical waveforms obtained by direct integration of the post-Newtonian equations of motion and discrete Fourier transformations. Such a waveform family lays the foundations for the accurate inclusion of spin precession effects in analytical gravitational waveforms, and thus, it can aid in the detection and parameter estimation of gravitational wave signals from the inspiral phase of precessing binary systems.

We find the Gregory-Laflamme $s$-mode instability of the nonrotating Banados-Teitelboim-Zanelli (BTZ) black hole in new massive gravity. This instability shows that the BTZ black hole could not exist as a stable static solution to the new massive gravity. For a nonrotating BTZ black string in four dimensions, however, it is demonstrated that the BTZ black string can be stable against the metric perturbation.

Starting from the equations of modified gravity hydrodynamics, we derive the equations of motion governing linear, adiabatic, radial perturbations of stars in scalar-tensor theories. There are two new features: first, the eigenvalue equation for the period of stellar oscillations is modified such that the eigenfrequencies are always larger than predicted by general relativity. Second, the general relativity condition for stellar instability is altered so that the adiabatic index can fall below $4/3$ before unstable modes appear. Stars are more stable in modified gravity theories. Specializing to the case of chameleonlike theories, we investigate these effects numerically using both polytropic Lane-Emden stars and models coming from modified gravity stellar structure simulations. We find that the change in the oscillation period of Cepheid star models can be as large as 30% for order-one matter couplings and the change in the inferred distance using the period-luminosity relation can be up to three times larger than if one had only considered the modified equilibrium structure. We discuss the implications of these results for recent and upcoming astrophysical tests and estimate that previous methods can produce new constraints such that the modifications are screened in regions of Newtonian potential of $\mathcal{O}({10}^{-8})$.

Cosmology with a three-form field interacting with cold dark matter is considered. In particular, the mass of the dark matter particles is assumed to depend upon the amplitude of the three-form field invariant. In comparison to coupled scalar field quintessence, the new features include an effective pressure contribution to the field equations that manifests both in the background and perturbation level. The dynamics of the background is analyzed, and new scaling solutions are found. A simple example model leading to a de Sitter expansion without a potential is studied. The Newtonian limit of cosmological perturbations is derived, and it is deduced that the coupling can be very tightly constrained by the large-scale structure data. This is demonstrated with numerical solutions for a model with nontrivial coupling and a quadratic potential.

We present the results of a first search for self-annihilating dark matter in nearby galaxies and galaxy clusters using a sample of high-energy neutrinos acquired in 339.8 days of live time during 2009/10 with the IceCube neutrino observatory in its 59-string configuration. The targets of interest include the Virgo and Coma galaxy clusters, the Andromeda galaxy, and several dwarf galaxies. We obtain upper limits on the cross section as a function of the weakly interacting massive particle mass between 300 GeV and 100 TeV for the annihilation into $b\overline{b}$, $W^{+}{W}^{-}$, ${\tau }^{+}{\tau }^{-}$, ${\mu }^{+}{\mu }^{-}$, and $\nu \overline{\nu }$. A limit derived for the Virgo cluster, when assuming a large effect from subhalos, challenges the weakly interacting massive particle interpretation of a recently observed GeV positron excess in cosmic rays.

We consider binary systems of coalescing, nonspinning, black holes of masses $m_1$ and $m_2$ and show that the gravitational recoil velocity for any mass ratio can be obtained accurately by extrapolating the waveform of the test-mass limit case. The waveform obtained in the limit $m_1/m_2\ll 1$ via a perturbative approach is extrapolated in $\nu =m_1{m}_2/(m_1+m_2{)}^2$ multipole by multipole using the corresponding, analytically known, leading-in-$\nu$ behavior. The final kick velocity computed from this $\nu$-flexed waveform is written as $v(\nu )/c=0.04457{\nu }^2\sqrt{1-4\nu }(1-2.07106\nu +3.93472{\nu }^2-4.78404{\nu }^3+2.52040{\nu }^4)$ and is compatible with the outcome of numerical relativity simulations

In the present work we investigate the three-body systems of $\eta K\overline{K}$ and ${\eta }^{\prime }K\overline{K}$, by taking the fixed center approximation to Faddeev equations. We find a clear and stable resonance structure around 1490 MeV in the squared $\eta K\overline{K}$ scattering amplitude, which is not sensitive to the renormalization parameters. Conversely, we get only an enhancement effect of the threshold in the ${\eta }^{\prime }K\overline{K}$ amplitude that indicates the difficulty to bind the ${\eta }^{\prime }K\overline{K}$ system as a consequence of the ${\eta }^{\prime }K$ interaction being weaker than the $\eta K$ one. We associate the $\eta K\overline{K}$ state found to the $\eta (1475)$.

Recent measurements of exclusive $B^{-}\to {\tau }^{-}\nu$ and $B^0\to {\pi }^{+}{l}^{-}{\overline{\nu }}_l$ decays via the $b\to ul\nu$ transition process differ from the standard model expectation and, if they persist in future $B$ experiments, will be a definite hint of the physics beyond the standard model. Similar hints of new physics have been observed in $b\to c$ semileptonic transition processes as well. BABAR measures the ratio of branching fractions of $B\to (D,D^{*})\tau \nu$ to the corresponding $B\to (D,D^{*})l\nu$, where $l$ represents either an electron or a muon, and finds $3.4\sigma$ discrepancy with the standard model expectation. In this context, we consider a most general effective Lagrangian for the $b\to ul\nu$ and $b\to cl\nu$ transition processes in the presence of new physics and perform a combined analysis of all the $b\to u$ and $b\to c$ semi-(leptonic) data to explore various new physics operators and their couplings. We consider various new physics scenarios and give predictions for the $B_c\to \tau \nu$ and $B\to \pi \tau \nu$ decay branching fractions. We also study the effect of these new physics parameters on the ratio of the branching ratios of $B\to \pi \tau \nu$ to the corresponding $B\to \pi l\nu$ decays.