We give the first self-consistent calculation of the effect of the scattered neutrino halo on flavor evolution in supernovae. Our example case is an O-Ne-Mg core collapse supernova neutronization neutrino burst. We find that the addition of the halo neutrinos produces qualitative and quantitative changes in the final flavor states of neutrinos. We also find that the halo neutrinos produce a novel distortion of the neutrino flavor swap. Our results provide strong motivation for tackling the full multidimensional and composition-dependent aspects of this problem in the future.

We discuss infrared (IR) divergences in lepton mass renormalization in light-front quantum electrodynamics in Feynman gauge. We consider light-front quantum electrodynamics with Pauli-Villars fields and using old-fashioned time-ordered perturbation theory, we show that our earlier result regarding cancellation of true IR divergences up to $O(e^4)$ in coherent state basis holds in Feynman gauge also.

The Skyrme crystal is built up of repeating units similar to the cubic Skyrmion of baryon number 4. Using this as a guide, we construct new Skyrmion solutions in the massive-pion case, with various baryon numbers up to 108. Most of our solutions resemble chunks of the Skyrme crystal. They are constructed using a multilayer version of the rational map ansatz to create initial configurations, which are then relaxed numerically to find the energy minima. The coefficients of the rational maps are found by a geometrical construction related to the Skyrme crystal structure. We find some further solutions by numerical relaxation of clusters composed of baryon number 4 Skyrmions.

We study the theoretical features in relation to dynamical mass generation and symmetry breaking for the recently proposed holomorphic supersymmetric Nambu–Jona-Lasinio model. The basic model has two different chiral superfields (multiplets) with a strongly coupled dimension five four-superfield interaction. In addition to the possibility of generation of Dirac mass between the pair established earlier, we show here the new option of generation of Majorana masses for each chiral superfield. We also give a first look at what condition may prefer Dirac over Majorana mass, illustrating that a split in the soft supersymmetry breaking masses is crucial. In particular, in the limit where one of the soft masses vanish, we show that generation of the Majorana mass is no longer an option, while the Dirac mass generation survives well. The latter is sensitive mostly to the average of the two soft masses. The result has positive implication on the application of the model framework towards dynamical electroweak symmetry breaking with Higgs superfields as composites.

We deform the well-known three-dimensional $\mathcal{N}=1$ Wess-Zumino model by adding higher derivative operators (Lee-Wick operators) to its action. The effects of these operators are investigated both at the classical and quantum levels.

We consider stationary, cylindrically symmetric configurations in general relativity and formulate necessary conditions for the existence of rotating cylindrical wormholes. It is shown that in a comoving reference frame, the rotational part of the gravitational field is separated from its static part and forms an effective stress-energy tensor with exotic properties, which favors the existence of wormhole throats. Exact vacuum and scalar-vacuum solutions (with a massless scalar) are considered as examples, and it turns out that even vacuum solutions can be of wormhole nature. However, solutions obtainable in this manner cannot have well-behaved asymptotic regions, which excludes the existence of wormhole entrances appearing as local objects in our Universe. To overcome this difficulty, we try to build configurations with flat asymptotic regions by the cut-and-paste procedure: on both sides of the throat, a wormhole solution is matched to a properly chosen region of flat space at surfaces ${\Sigma }_{-}$ and ${\Sigma }_{+}$. It is shown, however, that if we describe the throat region with vacuum or scalar-vacuum solutions, one or both thin shells appearing on ${\Sigma }_{-}$ and ${\Sigma }_{+}$ inevitably violate the null energy condition. In other words, although rotating wormhole solutions are easily found without exotic matter, such matter is still necessary for obtaining asymptotic flatness.

We study a smooth cosmological solution within a generalized 5D standing wave braneworld modeled by gravity and a phantom scalar field. In this model the 3-brane is anisotropically warped along its spatial dimensions and contains a novel time-dependent scale factor that multiplies the anisotropic spatial interval of the 5D metric, a fact that allows us to study cosmological effects. By explicitly solving the bulk field equations we found a natural mechanism which isotropizes the braneworld for a wide class of natural initial conditions. We are able to give a physical interpretation of the anisotropic dissipation: as the anisotropic energy of the 3-brane rapidly leaks into the bulk through the nontrivial components of the nonlocal Weyl tensor projected to the brane, the bulk becomes less isotropic. At the same time, under the action of the 4D cosmological constant, the anisotropic braneworld super-exponentially isotropizes by itself, rendering a 3-brane with de Sitter symmetry embedded in a 5D de Sitter space-time, while the phantom scalar field exponentially vanishes.

We study isolated and binary neutron stars in dynamical Chern-Simons gravity. This theory modifies the Einstein-Hilbert action through the introduction of a dynamical scalar field coupled to the Pontryagin density. We here treat this theory as an effective model, working to leading order in the Chern-Simons coupling. We first construct isolated neutron star solutions in the slow-rotation expansion to quadratic order in spin. We find that isolated neutron stars acquire a scalar dipole charge that corrects its spin angular momentum to linear order in spin and corrects its mass and quadrupole moment to quadratic order in spin, as measured by an observer at spatial infinity. We then consider neutron stars binaries that are widely separated and solve for their orbital evolution in this modified theory. We find that the evolution of post-Keplerian parameters is modified, with the rate of periastron advance being the dominant correction at first post-Newtonian order. We conclude by applying these results to observed pulsars with the aim to place constraints on dynamical Chern-Simons gravity. We find that the modifications to the observed mass are degenerate with the neutron star equation of state, which prevents us from testing the theory with the inferred mass of the millisecond pulsar J1614-2230. We also find that the corrections to the post-Keplerian parameters are too small to be observable today even with data from the double binary pulsar J0737-3039. Our results suggest that pulsar observations are not currently capable of constraining dynamical Chern-Simons gravity, and thus, gravitational-wave observations may be the only path to a stringent constraint of this theory in the imminent future.

The conformal invariance of unimodular gravity survives quantum corrections, even in the presence of conformal matter. Unimodular gravity can actually be understood as a certain truncation of the full Einstein-Hilbert theory, where in the Einstein frame the metric tensor has unit determinant. Our result is compatible with the idea that the corresponding restriction in the functional integral is consistent as well.

The precise of short gamma ray bursts (SGRBs) remains an important open question in relativistic astrophysics. Increasingly, observational evidence suggests the merger of a binary compact object system as the source for most SGRBs, but it is currently unclear how to distinguish observationally between a binary neutron star progenitor and a black hole-neutron star progenitor. We suggest the quasiperiodic signal of jet precession as an observational signature of SGRBs originating in mixed binary systems, and quantify both the fraction of mixed binaries capable of producing SGRBs and the distributions of precession amplitudes and periods. The difficulty inherent in disrupting a neutron star outside the horizon of a stellar mass black hole biases the jet precession signal towards low amplitude and high frequency. Precession periods of $\sim 0.01–0.1\mathrm{s}$ and disk-black hole spin misalignments $\sim 10°$ are generally expected, although sufficiently high viscosity may prevent the accumulation of multiple precession periods during the SGRB. The precessing jet will naturally cover a larger solid angle in the sky than would standard SGRB jets, enhancing observability for both prompt emission and optical afterglows.

We prove a new type of finite time blowup for a class of semilinear wave equations on extremal black holes. The initial data can be taken to be arbitrarily close to the trivial data. The first singularity occurs along the (degenerate) future event horizon. No analogue of this instability occurs for subextremal black holes or the Minkowski spacetime.

In completely local settings, we establish that a spherically symmetric, dynamically evolving black hole horizon can be assigned a Hawking temperature under a mild assumption. Moreover, we calculate the Hawking flux and show that the radius of the horizon shrinks in accordance with the amount of emitted flux.

We present a new approach to computing the matter density power spectrum, from large linear scales to small, highly nonlinear scales. Instead of explicitly computing a partial series of high-order diagrams, as in perturbative resummation schemes, we embed the standard perturbation theory within a realistic nonlinear Lagrangian-space ansatz. We also point out that an “adhesion-like” regularization of the shell-crossing regime is more realistic than a “Zel’dovich-like” behavior, where particles freely escape to infinity. This provides a “cosmic web” power spectrum with good small-scale properties that provide a good matching with a halo model on mildly nonlinear scales. We obtain a good agreement with numerical simulations on large scales, better than 3% for $k\le 1h{\mathrm{Mpc}}^{-1}$, and on small scales, better than 10% for $k\le 10h{\mathrm{Mpc}}^{-1}$, at $z\ge 0.35$, which improves over previous methods.

We investigate constraints on early dark energy (EDE) from the cosmic microwave background (CMB) anisotropy, taking into account data from WMAP9 combined with the latest small-scale measurements from the South Pole Telescope (SPT). For a constant EDE fraction we propose a new parametrization with one less parameter but still enough to provide similar results to the ones previously studied in the literature. The main emphasis of our analysis, however, compares a new set of different EDE parametrizations that reveal how CMB constraints depend on the redshift epoch at which dark energy was non-negligible. We find that bounds on EDE get substantially weaker if dark energy starts to be non-negligible later, with the early dark energy fraction ${\Omega }_e$ free to go up to about 5% at two sigma if the onset of EDE happens at $z\lesssim 100$. Tight bounds around 1–2% are obtained whenever dark energy is present at last scattering, even if its effects switch off afterwards. We show that the CMB mainly constrains the presence of dark energy at the time of its emission, while EDE modifications of the subsequent growth of structure are less important.

We explore the physical origin and robustness of constraints on the energy density in relativistic species prior to and during recombination, often expressed as constraints on an effective number of neutrino species, $N_{\mathrm{eff}}$. If the primordial helium abundance, $Y_{\mathrm{P}}$, follows the prediction of the big bang nucleosynthesis (BBN) theory, the constraint on $N_{\mathrm{eff}}$ from current cosmic microwave background anisotropy data is almost entirely due to the impact of the neutrinos on the expansion rate, and how those changes to the expansion rate alter the ratio of the photon diffusion scale to the sound horizon scale at recombination. We demonstrate that, as long as the primordial helium abundance is derived in a BBN-consistent manner, the constraint on $N_{\mathrm{eff}}$ degrades little after marginalizing over $A_{\mathrm{eISW}}$, the phenomenological parameter characterizing the amplitude of the early Integrated Sachs-Wolfe (ISW) effect. We also provide a first determination of $A_{\mathrm{eISW}}$. Varying the $Y_{\mathrm{P}}$ also changes the ratio of damping to sound horizon scales. We study the physical effects that prevent the resulting near degeneracy between $N_{\mathrm{eff}}$ and $Y_{\mathrm{P}}$ from being a complete one and find that the early ISW effect does play a role in breaking this degeneracy. Examining light-element abundance measurements, we see no significant evidence for the evolution of $N_{\mathrm{eff}}$ and the baryon-to-photon ratio from the epoch of BBN to decoupling. Finally, we consider measurements of the distance-redshift relation at low to intermediate redshifts and their implications for the value of $N_{\mathrm{eff}}$.

Imperfect cavity mirrors in the arms of an interferometric gravitational-wave (GW) detector can result in the generation of unwanted higher order modes that are close to or at resonance in the cavity. This can lead to many undesirable effects such as increased round-trip losses or degraded contrast defect. Polishing mirrors to fulfill the requirements of 2nd generation GW interferometers is extremely challenging. For the use of LG33 modes in 3rd generation detectors it would be necessary to improve polishing by an order of magnitude. In this article we present a novel technique for the in situ correction of cavity mirror surface figures by central heating residual aberration correction. This system targets and corrects specific features of the mirror surface figure such as to reduce scattering from the fundamental cavity mode to specific higher order modes by more than an order of magnitude. We demonstrate, by simulation, the feasibility of such a system and give examples of its application to 2nd and 3rd generation GW interferometers.

We performed a search for short gravitational wave bursts using about 3 years of data of the resonant bar detectors Nautilus and Explorer. Two types of analysis were performed: a search for coincidences with a low background of accidentals (0.1 over the entire period), and the calculation of upper limits on the rate of gravitational wave bursts. Here we give a detailed account of the methodology and we report the results: a null search for coincident events and an upper limit that improves over all previous limits from resonant antennas, and is competitive, in the range $h_{\mathrm{rss}}\sim {10}^{-19}$, with limits from interferometric detectors. Some new methodological features are introduced that have proven successful in the upper limits evaluation.

Using trace anomalies, we determine the vacuum stress tensors of arbitrary even-dimensional conformal field theories in Weyl flat backgrounds. We demonstrate a simple relation between the Casimir energy on $\mathbb{R}\times S^{d-1}$ and the type A anomaly coefficient. This relation generalizes earlier results in two and four dimensions. These field-theory results for the Casimir energy are shown to be consistent with holographic predictions in two, four, and six dimensions.

The area law of Bekenstein-Hawking entropy of the black hole suggests that the black hole should have a lower-dimensional holographic description. It has been found recently that such holographic pictures could be set up from the study of the thermodynamics of both outer and inner horizons for a large class of rotating and charged black holes. For a four-dimensional dyonic Reissner-Nordström black hole, its thermodynamics indicates that it has multiple holographic pictures—not only the electric and magnetic ones corresponding to the conserved electric and magnetic charges carried by the black hole, but also the more generic ones generated by the $SL(2,Z)$ transformations. We show that this $SL(2,Z)$ group originates from the underlying electromagnetic duality symmetry in the Einstein-Maxwell theory. It turns out that the thermodynamics of the black hole not only encodes the information of holographic pictures; moreover, it could reflect the symmetries of the underlying theory.

We show that the static and asymptotically flat black hole spacetime is unique to be Schwarzschild spacetime in the dynamical Chern-Simons gravity. In addition, we show that the strictly static spacetimes should be the Minkowski spacetime.