The Antarctic Impulsive Transient Antenna (ANITA) completed its second Long Duration Balloon flight in January 2009, with 31 days aloft (28.5 live days) over Antarctica. ANITA searches for impulsive coherent radio Cherenkov emission from 200 to 1200 MHz, arising from the Askaryan charge excess in ultrahigh energy neutrino-induced cascades within Antarctic ice. This flight included significant improvements over the first flight in payload sensitivity, efficiency, and flight trajectory. Analysis of in-flight calibration pulses from surface and subsurface locations verifies the expected sensitivity. In a blind analysis, we find 2 surviving events on a background, mostly anthropogenic, of $0.97\pm 0.42$ events. We set the strongest limit to date for ${10}^{18}–{10}^{21}\mathrm{eV}$ cosmic neutrinos, excluding several current cosmogenic neutrino models.

We study the character change of the pionic condensation at finite isospin chemical potential ${\mu }_{\mathrm{I}}$ by adopting the linear sigma model as a nonlocal interaction between quarks. At low $|{\mu }_{\mathrm{I}}|$ the condensation is purely bosonic, then the Cooper pairing around the Fermi surface grows gradually as $|{\mu }_{\mathrm{I}}|$ increases. This $q\mathrm{\text{−}}\overline{q}$ pairing is weakly coupled in comparison with the case of the $q\mathrm{\text{−}}q$ pairing that leads to color superconductivity.

It is shown that natural doublet-triplet splitting can be achieved in a relatively simple way in supersymmetric $SU(N)\times U(1)$ models with $N>5$.

The critical temperature and the nature of the QCD finite temperature phase transition are determined for $N_f=2$ dynamical flavors of nonperturbatively improved Wilson fermions. The calculations are performed on large lattices with temporal extents $N_t=12$, 10, and 8, and lattice spacings down to $a=0.075\mathrm{fm}$. We find that the deconfinement and chiral phase transitions take place at the same temperature. Our results are in broad agreement with a second order phase transition in the chiral limit. The critical temperature at the physical quark mass is found to be $T_c=174(3)(6)\mathrm{MeV}$.

The tribimaximal (TBM) mixing is not accidental if structures of the corresponding leptonic mass matrices follow immediately from certain (residual or broken) flavor symmetry. We develop a simple formalism which allows one to analyze effects of deviations of the lepton mixing from TBM on the structure of the neutrino mass matrix and on the underlying flavor symmetry. We show that possible deviations from the TBM mixing can lead to strong modifications of the mass matrix and strong violation of the TBM-mass relations. As a result, the mass matrix may have an “anarchical” structure with random values of elements or it may have some symmetry that differs from the TBM symmetry. Interesting examples include matrices with texture zeros, matrices with certain “flavor alignment” as well as hierarchical matrices with a two-component structure, where the dominant and subdominant contributions have different symmetries. This opens up new approaches to understanding the lepton mixing.

One of the main challenges of the Tevatron at Fermilab and the Large Hadron Collider (LHC) at CERN is the determination of standard model parameters at the TeV scale. In this context various processes will be investigated which involve bottom-quark jets in the final state, for example, decays of top-quarks or gauge bosons of the weak interaction. Hence the theoretical understanding of processes with bottom-quark jets is necessary. In this paper analytic results will be presented for the weak corrections to bottom-quark jet production—neglecting purely photonic corrections. The results will be used to study differential distributions, where sizeable effects are observed.

In charged current weak interaction processes, neutrinos are produced in an entangled state with the charged lepton. This correlated state is disentangled by the measurement of the charged lepton in a detector at the production site. We study the dynamical aspects of disentanglement, propagation, and detection, in particular, the conditions under which the disentangled state is a coherent superposition of mass eigenstates. The appearance and disappearance far-detection processes are described from the time evolution of this disentangled “collapsed” state. The familiar quantum mechanical interpretation and factorization of the detection rate emerges when the quantum state is disentangled on time scales much shorter than the inverse oscillation frequency, in which case the final detection rate factorizes in terms of the usual quantum mechanical transition probability provided the final density of states is insensitive to the neutrino energy difference. We suggest possible corrections for short-baseline experiments. If the charged lepton is unobserved, neutrino oscillations and coherence are described in terms of a reduced density matrix obtained by tracing out an unobserved charged lepton. The diagonal elements in the mass basis describe the production of mass eigenstates whereas the off-diagonal ones provide a measure of coherence. It is shown that coherences are of the same order of the diagonal terms on time scales up to the inverse oscillation frequency, beyond which the coherences oscillate as a result of the interference between mass eigenstates.

We review the idea of leptonic unitary triangles and extend the concept of the recently proposed unitary boomerangs to the lepton sector. Using a convenient parametrization of the lepton mixing, we provide approximate expressions for the side lengths and the angles of the six different triangles and give examples of leptonic unitary boomerangs. Possible applications of the leptonic unitary boomerangs are also briefly discussed.

Analytic exact expressions for the quasinormal modes of scalar and electromagnetic perturbations around a special class of black holes are found in $d\ge 3$ dimensions. It is shown that the size of the black hole provides a lower bound for the angular momentum of the perturbation. Quasinormal modes appear when this bound is fulfilled; otherwise the excitations become purely damped.

Recently N. Berkovits, motivated by the supertwistor description of $\mathcal{N}=4$ $D=4$ super Yang-Mills, considered the generalization of the $\mathcal{N}=1$ $D=4$ $\theta$-twistor construction to $D=10$ and applied it for a compact covariant description of $\mathcal{N}=1$ $D=10$ super Yang-Mills. This supports the relevance of the $\theta$-twistor as a supersymmetric twistor alternative to the well-known supertwistor. The minimal breaking of superconformal symmetry is an inherent property of the $\theta$-twistor received from its fermionic components, described by a Grassmannian vector instead of a Grassmannian scalar in the supertwistor. The $\theta$-twistor description of the $\mathcal{N}=1$ $D=4$ massless chiral supermultiplets ($S$, $S+1/2$) with spins $S=0,1/2,1,3/2,2,\dots$ is considered here. The description permits to restore the auxiliary $F$ fields of the chiral supermultiplets absent in the supertwistor approach. The proposed formalism is naturally generalized to $\mathcal{N}=4$ $D=4$ and can be used for an off-shell description of the corresponding super Yang-Mills theory.

We study the existence and stability of static kinklike configurations of a five-dimensional scalar field, with Dirichlet boundary conditions, along the extra dimension of a warped braneworld. In the presence of gravity such configurations fail to stabilize the size of the extra dimension, leading us to consider additional scalar fields with the role of stabilization. We numerically identify multiple nontrivial solutions for a given five-dimensional action, made possible by the nonlinear nature of the background equations, which we find is enhanced in the presence of gravity. Finally, we take a first step toward addressing the question of the stability of such configurations by deriving the full perturbative equations for the gravitationally coupled multifield system.

We study the stress-energy two-point function to show how short distance correlations across the horizon transform into correlations among asymptotic states, for the Unruh effect, and for black hole radiation. In the first case, the transition is caused by the coupling to accelerated systems. In the second, the transition is more elusive and due to the change of the geometry from the near horizon region to the asymptotic one. The gradual transition is appropriately described by using affine coordinates. We relate this to the covariant regularization used to evaluate the mean value of the stress energy. We apply these considerations to analogue black holes, i.e. dispersive theories. On one hand, the preferred rest frame gives further insight about the transition, and on the other hand, the dispersion tames the singular behavior found on the horizon in relativistic theories.

We obtain a general five-dimensional quasispherical collapsing solutions of irrotational dust in Einstein gravity with the Gauss-Bonnet combination of quadratic curvature terms. These solutions are a generalization, to Einstein-Gauss-Bonnet gravity, of the five-dimensional quasispherical Szkeres like collapsing solutions in general relativity. It is found that the collapse proceeds in the same way as in the analogous spherical collapse, i.e., there exists regular initial data such that the collapse proceed to form naked singularities violating cosmic censorship conjecture. The effect of Gauss-Bonnet quadratic curvature terms on the formation and locations of the apparent horizon is deduced.

Gravitational waves from the final stages of inspiraling binary neutron stars are expected to be one of the most important sources for ground-based gravitational wave detectors. The masses of the components are determinable from the orbital and chirp frequencies during the early part of the evolution, and large finite-size (tidal) effects are measurable toward the end of inspiral, but the gravitational wave signal is expected to be very complex at this time. Tidal effects during the early part of the evolution will form a very small correction, but during this phase the signal is relatively clean. The accumulated phase shift due to tidal corrections is characterized by a single quantity related to a star’s tidal Love number. The Love number is sensitive, in particular, to the compactness parameter $M/R$ and the star’s internal structure, and its determination could provide an important constraint to the neutron star radius. We show that Love numbers of self-bound strange quark matter stars are qualitatively different from those of normal neutron stars. Observations of the tidal signature from coalescing compact binaries could therefore provide an important, and possibly unique, way to distinguish self-bound strange quark stars from normal neutron stars. Tidal signatures from self-bound strange quark stars with masses smaller than $1M_{\odot }$ are substantially smaller than those of normal stars owing to their smaller radii. Thus tidal signatures of stars less massive than $1M_{\odot }$ are probably not detectable with Advanced LIGO. For stars with masses in the range $1–2M_{\odot }$, the anticipated efficiency of the proposed Einstein telescope would be required for the detection of tidal signatures.

In the present paper, we prove a uniqueness theorem for stationary multi–black hole configurations with Kaluza-Klein asymptotic in a certain sector of 5D Einstein-Maxwell gravity. As a part of the technical assumptions in the theorem, we assume that the Killing vector associated with the compact dimension is orthogonal to the other Killing vectors and that it is also hypersurface orthogonal. About the Maxwell field, we assume that it is invariant under the Killing symmetries and has a nonzero component only along the Killing vector associated with the compact dimension. We show that such multi–black hole configurations are uniquely specified by the interval structure, angular momenta of the horizons, magnetic charges, and the magnetic flux. A straightforward generalization of the uniqueness theorem for 5D Einstein-Maxwell-dilaton gravity is also given.

Advances in the field of numerical relativity now make it possible to calculate the final, most powerful merger phase of binary black-hole coalescence for generic binaries. The state of the art has advanced well beyond the equal-mass case into the unequal-mass and spinning regions of parameter space. We present a study of the nonspinning portion of parameter space, primarily using an analytic waveform model tuned to available numerical data, with an emphasis on observational implications. We investigate the impact of varied mass-ratio on merger signal-to-noise ratios for several detectors, and compare our results with expectations from the test-mass limit. We note a striking similarity of the waveform phasing of the merger waveform across the available mass ratios. Motivated by this, we calculate the match between our 1:1 (equal-mass) and 4:1 mass-ratio waveforms during the merger as a function of location on the source sky, using a new formalism for the match that accounts for higher harmonics. This is an indicator of the amount of degeneracy in mass-ratio for mergers of moderate-mass-ratio systems.

In the study of Planck-scale (“quantum-gravity-induced”) violations of Lorentz symmetry, an important role was played by the deformed-electrodynamics model introduced by Myers and Pospelov. Its reliance on conventional effective quantum field theory, and its description of symmetry-violation effects simply in terms of a four-vector with a nonzero component only in the time direction, rendered it an ideal target for experimentalists and a natural concept-testing ground for many theorists. At this point however the experimental limits on the single Myers-Pospelov parameter, after improving steadily over these past few years, are “super-Planckian”; i.e. they take the model out of actual interest from a conventional quantum-gravity perspective. In light of this we here argue that it may be appropriate to move on to the next level of complexity, still with vectorial symmetry violation but adopting a generic four-vector. We also offer a preliminary characterization of the phenomenology of this more general framework, sufficient to expose a rather significant increase in complexity with respect to the original Myers-Pospelov setup. Most of these novel features are linked to the presence of spatial anisotropy, which is particularly pronounced when the symmetry-breaking vector is spacelike, and they are such that they reduce the bound-setting power of certain types of observations in astrophysics.

We present the first Bayesian constraints on the single field inflationary reheating era obtained from cosmic microwave background (CMB) data. After demonstrating that this epoch can be fully characterized by the so-called reheating parameter, we show that it is constrained by the seven years Wilkinson microwave anisotropies probe (WMAP7) data for all large and small field models. An interesting feature of our approach is that it yields lower bounds on the reheating temperature which can be combined with the upper bounds associated with gravitinos production. For large field models, we find the energy scale of reheating to be higher than those probed at the Large Hadron Collider, ${\rho }_{\mathrm{reh}}^{1/4}>17.3\mathrm{TeV}$ at 95% of the confidence limit. For small field models, we obtain the two-sigma lower limits ${\rho }_{\mathrm{reh}}^{1/4}>890\mathrm{TeV}$ for a mean equation of state during reheating ${\overline{w}}_{\mathrm{reh}}=-0.3$ and ${\rho }_{\mathrm{reh}}^{1/4}>390\mathrm{GeV}$ for ${\overline{w}}_{\mathrm{reh}}=-0.2$. The physical origin of these constraints is pedagogically explained by means of the slow-roll approximation. Finally, when marginalizing over all possible reheating history, the WMAP7 data push massive inflation under pressure ($p<2.2$ at 95% of the confidence limit where $p$ is the power index of the large field potentials) while they slightly favor super-Planckian field expectation values in the small field models.

A non-Abelian generalization of the neutral Witten current-carrying string model is discussed in which the bosonic current carrier belongs to a two-dimensional representation of SU(2). We find that the current-carrying solutions can be of three different kinds: either the current spans a U(1) subgroup, and in which case one is left with an Abelian current-carrying string, or the three currents are all lightlike, traveling in the same direction (only left or right movers). The third, genuinely non-Abelian situation, cannot be handled within a cylindrically symmetric framework, but can be shown to depend on all possible string Lorentz invariant quantities that can be constructed out of the phase gradients.

We present here the results of a 515 day search for short bursts of gravitational waves by the IGEC2 observatory. This network included 4 cryogenic resonant-bar detectors: AURIGA, EXPLORER, and NAUTILUS in Europe, and ALLEGRO in America. These results cover the time period from November 6th 2005 until April 15th 2007, partly overlapping the first long term observations by the LIGO interferometric detectors. The observatory operated with high duty cycle, namely, 57% for fourfold coincident observations, and 94% for threefold observations. The sensitivity was the best ever obtained by a bar network: we could detect, with an efficiency $>50\%$, impulsive events with a burst strain amplitude $h_{rss}\lesssim 1\times {10}^{-19}{\mathrm{Hz}}^{-1/2}$. The network data analysis was based on time coincidence searches over at least three detectors, used a blind search technique, and was tuned to achieve a false alarm rate of $1/\mathrm{\text{century}}$. When the blinding was removed, no gravitational wave candidate was found.