We study the evolution of magnetized and rigidly rotating neutron stars within a fully general relativistic implementation of ideal magnetohydrodynamics with no assumed symmetries in three spatial dimensions. The stars are modeled as rotating, magnetized polytropic stars, and we examine diverse scenarios to study their dynamics and stability properties. In particular, we concentrate on the stability of the stars and possible critical behavior. In addition to their intrinsic physical significance, we use these evolutions as further tests of our implementation, which incorporates new developments to handle magnetized systems.

Cylindrically symmetric solutions in conformal gravity are investigated and several new solutions are presented and discussed, among them a family of vacuum solutions, generalizations of the Melvin solution, and cosmic strings of the Abelian Higgs model. The Melvin-like solutions have finite energy per unit length, while the stringlike solutions do not.

Inflation predicts primordial scalar perturbations with a nearly scale-invariant spectrum and a spectral index approximately unity [the Harrison–Zel’dovich (HZ) spectrum]. The first important step for inflationary cosmology is to check the consistency of the HZ primordial spectrum with current observations. Recent analyses have claimed that a HZ primordial spectrum is excluded at more than 99% c.l. Here we show that the HZ spectrum is only marginally disfavored if one considers a more general reionization scenario. Data from the Planck mission will settle the issue.

Deviations from general relativity, such as could be responsible for the cosmic acceleration, would influence the growth of large-scale structure and the deflection of light by that structure. We clarify the relations between several different model-independent approaches to deviations from general relativity appearing in the literature, devising a translation table. We examine current constraints on such deviations, using weak gravitational lensing data of the CFHTLS and COSMOS surveys, cosmic microwave background radiation data of WMAP5, and supernova distance data of Union2. A Markov chain Monte Carlo likelihood analysis of the parameters over various redshift ranges yields consistency with general relativity at the 95% confidence level.

If dark matter annihilation accounts for the tantalizing excess of cosmic ray electron/positrons, as reported by the PAMELA, ATIC, HESS, and FERMI observatories, then the implied annihilation cross section must be relatively large. This results, in the context of standard cosmological models, in very small relic dark matter abundances that are incompatible with astrophysical observations. We explore possible resolutions to this apparent conflict in terms of nonstandard cosmological scenarios; plausibly allowing for large cross sections, while maintaining relic abundances in accord with current observations.

We comment on the recent observation of the decay mode $D_{sJ}^{*}(2860{)}^{+}\to D^{*}K$ by the BABAR Collaboration [B. Aubert et al. (BABAR Collaboration), arXiv:0908.0806], and contest their conclusion that the data exclude a $0^{+}$ assignment for the $D_{sJ}^{*}(2860{)}^{+}$. In particular, we argue that the observed branching fraction $\mathcal{B}(D_{sJ}^{*}(2860{)}^{+}\to D^{*}K)/\mathcal{B}(D_{sJ}^{*}(2860{)}^{+}\to DK)=1.1\pm 0.15\pm 0.19$ supports the existence of two largely overlapping resonances at about 2.86 GeV, namely, a pair of radially excited tensor ($2^{+}$) and scalar ($0^{+}$) $c\overline{s}$ states. This scenario is further justified by comparing with the corresponding excited charmonium states. Also other aspects of the charm-strange spectrum are discussed.

Vector mesons as $\phi$, $\omega$, and $J/\Psi$ with $J^{PC}=1^{--}$ are produced at colliding electron-positron high energy beams through the annihilation and the scattering channels. We consider here the scattering mechanism, namely, the creation of a vector meson in the fragmentation region of one of the initial leptons. It corresponds to the kinematics where the vector meson is emitted close to the direction of one of the colliding leptons, while the direction of the other lepton remains close to the initial one. The annihilation channel contribution is enhanced by the initial hard photon emission mechanism. It occurs in the kinematical region where the final particles are emitted at large angles and plays the role of background. Differential distributions of the energy fraction and of the transverse component of the vector meson are calculated. The relevant formalism and the numerical estimations are presented.

We present a calculation of next-to-leading order QCD corrections to $\gamma jj$ production via weak-boson fusion at a hadron collider in the form of a flexible parton-level Monte Carlo program which allows us to study cross sections and distributions within experimentally relevant selection cuts. The radiative corrections are found to be moderate with residual scale uncertainties being considerably improved beyond tree level. The sensitivity of the reaction to anomalous $W^{+}{W}^{-}\gamma$ couplings is investigated.

We extrapolate the first moments of the generalized parton distributions using heavy baryon chiral perturbation theory. The calculation is based on the one loop level with the finite range regularization. The description of the lattice data is satisfactory, and the extrapolated moments at physical pion mass are consistent with the results obtained with dimensional regularization, although the extrapolation in the momentum transfer to $t=0$ does show sensitivity to form factor effects, which lie outside the realm of chiral perturbation theory. We discuss the significance of the results in the light of modern experiments as well as QCD inspired models.

We consider searching for light sterile fermions and new forces by using long baseline oscillations of neutrinos and antineutrinos. A new light sterile state and/or a new force can lead to apparent $CPT$ violation in muon neutrino and antineutrino oscillations. As an example, we present an economical model of neutrino masses containing a sterile neutrino. The potential from the standard model weak neutral current gives rise to a difference between the disappearance probabilities of neutrinos and antineutrinos, when mixing with a light sterile neutrino is considered. The addition of a $B-L$ interaction adds coherently to the neutrino current potential and increases the difference between neutrino and antineutrino disappearance. We find that this model can improve the fit to the results of MINOS for both neutrinos and antineutrinos, without any $CPT$ violation, and that the regions of parameter space which improve the fit are within experimental constraints.

We demonstrate that the Higgs boson can be discovered at the large hadron collider in new physics events using boosted kinematics, $b$-tagging and jet substructure. This method superbly identifies the lightest Higgs boson in the minimal supersymmetric standard model. Two case studies are considered where Higgs is produced in association with superpartners that decay to a light gravitino, however generalizations to other spectra and models is anticipated. In some circumstances, discovery of the lightest Higgs is possible before conventional search strategies uncover convincing evidence.

In this article we present new, genuinely non-Abelian vortex solutions in $SU(2)$ Yang-Mills–Higgs theory with only one isovector scalar field. These non-Abelian solutions branch off their Abelian counterparts (Abrikosov–Nielsen-Olesen vortices) for precise values of the Higgs potential coupling constant $\lambda$. For all values of $\lambda$, their energies lie below those of the Abelian energy profiles, the latter being logarithmically divergent as $\lambda \to \infty$. The non-Abelian branches plateau in the limit $\lambda \to \infty$ and their number increases with $\lambda$, this number becoming infinite. For each vorticity, the gaps between the plateauing energy levels become constant. In this limit the non-Abelian vortices are noninteracting and are described by the self-dual vortices of the $O(3)$ sigma model. In the absence of a topological lower bound, we expect these non-Abelian vortices to be sphalerons.

We study issues concerning perturbative integrability of $\mathcal{N}=6$ Chern-Simons theory at planar and weak ‘t Hooft coupling regime. By Feynman diagrammatics, we derive so-called maximal-ranged interactions in the quantum dilatation generator, originating from homogeneous and inhomogeneous diagrams. The dilatation operator requires proper regularization of ultraviolet and infrared divergences and also bears scheme dependence depending on operator-mixing or two-point function methods adopted. We first consider the standard operator-mixing method. We show that homogeneous diagrams are obtainable by recursive method to all orders. The method, however, is not easily extendable to inhomogeneous diagrams. We thus consider two-point function method and study both operator contents and the spectrum of the quantum dilatation generator up to six-loop orders. Within this scheme, we show that, of two possible classes of operators, only one linear combination actually contributes. Curiously, this is exactly the same combination as in $\mathcal{N}=4$ super Yang-Mills theory. From these operators, we extract a spectrum of anomalous dimension up to six loops. We find that the spectrum agrees perfectly with the prediction based on quantum integrability. In evaluating the six-loop diagrams, we utilized a remarkable integer-relation algorithm developed by Ferguson, Baily, and Arno.

The photon behavior in an arbitrary superposition of constant magnetic and electric fields is considered on most general grounds based on the first principles like Lorentz, gauge, charge, and parity invariance. We make model-independent and approximation-independent, but still rather informative, statements about the behavior that the requirement of causal propagation prescribes to massive and massless branches of dispersion curves, and describe the way the eigenmodes are polarized. We find, as a consequence of Hermiticity in the transparency domain, that adding a smaller electric field to a strong magnetic field in parallel to the latter causes enhancement of birefringence. We find the magnetic field produced by a point electric charge far from it—a manifestation of magnetoelectric phenomenon. We establish degeneracies of the polarization tensor that—under special kinematical conditions—occur due to space-time symmetries of the vacuum left after the external field is imposed.

In the presence of a chemical potential, the physics of level crossings leads to singularities at zero temperature, even when the spatial volume is finite. These singularities are smoothed out at a finite temperature but leave behind nontrivial finite size effects which must be understood in order to extract thermodynamic quantities using Monte Carlo methods, particularly close to critical points. We illustrate some of these issues using the classical nonlinear $O(2)$ sigma model with a coupling $\beta$ and chemical potential $\mu$ on a $2+1$-dimensional Euclidean lattice. In the conventional formulation this model suffers from a sign problem at nonzero chemical potential and hence cannot be studied with the Wolff cluster algorithm. However, when formulated in terms of the worldline of particles, the sign problem is absent, and the model can be studied efficiently with the “worm algorithm.” Using this method we study the finite size effects that arise due to the chemical potential and develop an effective quantum mechanical approach to capture the effects. As a side result we obtain energy levels of up to four particles as a function of the box size and uncover a part of the phase diagram in the $(\beta ,\mu )$ plane.

Lattice Monte Carlo studies in $SU(3)$ gauge theory have shown that the topological charge distribution in the vacuum is dominated by thin coherent membranes of codimension one arranged in a layered, alternating-sign sandwich. A similar lamination of topological charge occurs in the 2D $C{P}^{N-1}$ model. In holographic QCD, the observed topological charge sheets are naturally interpreted as $D6$ branes wrapped around an $S_4$. With this interpretation, the laminated array of topological charge membranes observed on the lattice can be identified as a “tachyonic crystal,” a regular, alternating-sign array of $D6$ and $\overline{D}6$ branes that arises as the final state of the decay of a non-BPS $D7$ brane via the tachyonic mode of the attached string. In the gauge theory, the homogeneous, space-filling $D7$ brane represents the perturbative gauge vacuum, which is unstable toward lamination associated with a marginal tachyonic boundary perturbation $\propto \cos (X/\sqrt{2{\alpha }^{\prime }})$. For the $C{P}^{N-1}$ model, the cutoff field theory can be cast as the low-energy limit of an open-string theory in background gauge and tachyon fields $A_{\mu }(x)$ and $\lambda (x)$. This allows a detailed comparison with large $N$ field theory results and provides strong support for the tachyonic crystal interpretation of the gauge theory vacuum.

Dynamical Chern-Simons gravity is an extension of general relativity in which the gravitational field is coupled to a scalar field through a parity-violating Chern-Simons term. In this framework, we study perturbations of spherically symmetric black hole spacetimes, assuming that the background scalar field vanishes. Our results suggest that these spacetimes are stable, and small perturbations die away as a ringdown. However, in contrast to standard general relativity, the gravitational waveforms are also driven by the scalar field. Thus, the gravitational oscillation modes of black holes carry imprints of the coupling to the scalar field. This is a smoking gun for Chern-Simons theory and could be tested with gravitational-wave detectors, such as LIGO or LISA. For negative values of the coupling constant, ghosts are known to arise, and we explicitly verify their appearance numerically. Our results are validated using both time evolution and frequency domain methods.

We investigate instability of four-dimensional Reissner-Nordström–anti-de Sitter (RN-${\mathrm{AdS}}_4$) black holes with various topologies by charged scalar field perturbations. We numerically find that the RN-${\mathrm{AdS}}_4$ black holes become unstable against the linear perturbations below a critical temperature. It is analytically shown that charge extraction from the black holes occurs during the unstable evolution. To explore the end state of the instability, we perturbatively construct static black hole solutions with the scalar hair near the critical temperature. It is numerically found that the entropy of the hairy black hole is always larger than the one of the unstable RN-${\mathrm{AdS}}_4$ black hole in the microcanonical ensemble. Our results support the speculation that the black hole with charged scalar hair always appears as the final fate of the instability of the RN-${\mathrm{AdS}}_4$ black hole.

We extend our maximum likelihood method for reconstructing the cluster-mass cross correlation from cosmic microwave background (CMB) temperature anisotropies and develop new estimators that utilize six different quadratic combinations of CMB temperature and polarization fields. Our maximum likelihood estimators are constructed with delensed CMB temperature and polarization fields by using an assumed model of the convergence field, and they can be iteratively applied to a set of clusters, approaching the optimal condition for the lensing reconstruction as the assumed initial model is refined. Using smoothed particle hydrodynamics simulations, we create a catalog of realistic clusters obtainable from the current Sunyaev-Zel’dovich surveys, and we demonstrate the ability of the maximum likelihood estimators to reconstruct the cluster-mass cross correlation from the massive clusters. The $iTT$ temperature estimator provides a signal-to-noise ratio of a factor of 3 larger than the $iEB$ polarization estimator, unless the detector noise for measuring polarization anisotropies is controlled under $3\mu \mathrm{K}$.

We present factorization theorems for two exclusive heavy-quarkonium production processes: production of two quarkonia in $e^{+}{e}^{-}$ annihilation and production of a quarkonium and a light meson in $B$-meson decays. We describe the general proofs of factorization and supplement them with explicit one-loop analyses, which illustrate some of the features of the soft-gluon cancellations. We find that violations of factorization are generally suppressed relative to the factorized contributions by a factor $v^2{m}_c/Q$ for each $S$-wave charmonium and a factor $m_c/Q$ for each $L$-wave charmonium with $L>0$. Here, $v$ is the velocity of the heavy quark or antiquark in the quarkonium rest frame, $Q=\sqrt{s}$ for $e^{+}{e}^{-}$ annihilation, $Q=m_B$ for $B$-meson decays, $\sqrt{s}$ is the $e^{+}{e}^{-}$ center-of-momentum energy, $m_c$ is the charm-quark mass, and $m_B$ is the $B$-meson mass. There are modifications to the suppression factors if quantum-number restrictions apply for the specific process.