We derive the Boltzmann equation in the synchronous gauge for massive neutrinos with a deformed dispersion relation. Combining the 7-year WMAP data with lower-redshift measurements of the expansion rate, we give constraints on the deformation parameter and find that the deformation parameter is strongly degenerate with the physical dark matter density rather than the neutrino mass. Our results show that there is no evidence for Lorentz invariant violation in the neutrino sector. The ongoing Planck experiment could provide improved constraints on the deformation parameter.

$n$-DBI gravity is a gravitational theory which yields near de Sitter inflation spontaneously at the cost of breaking Lorentz invariance by a preferred choice of foliation. We show that this breakdown endows $n$-DBI gravity with one extra physical gravitational degree of freedom: a scalar graviton. Its existence is established by Dirac’s theory of constrained systems. First, studying scalar perturbations around Minkowski space-time, we show that there exists one scalar degree of freedom and identify it in terms of the metric perturbations. Then, a general analysis is made in the canonical formalism, using Arnowitt-Deser-Misner variables. It is useful to introduce an auxiliary scalar field, which allows recasting $n$-DBI gravity in an Einstein-Hilbert form but in a Jordan frame. Identifying the constraints and their classes we confirm the existence of an extra degree of freedom in the full theory, besides the two usual tensorial modes of the graviton. We then argue that, unlike the case of (the original proposal for) Hořava-Lifschitz gravity, there is no evidence that the extra degree of freedom originates pathologies, such as vanishing lapse, instabilities, and strong self-coupling at low energy scales.

We construct a new three-dimensional general relativistic magnetohydrodynamics code, in which a fixed mesh refinement technique is implemented. To ensure the divergence-free condition as well as the magnetic flux conservation, we employ the method by Balsara [J. Comp. Physiol. 174, 614 (2001); J. Comp. Phys. 228, 5040 (2009)]. Using this new code, we evolve differentially rotating magnetized neutron stars, and find that a magnetically driven outflow is launched from the star exhibiting a kink instability. The matter ejection rate and Poynting flux are still consistent with our previous finding [M. Shibata, Y. Suwa, K. Kiuchi, and K. Ioka, Astrophys. J. 734, L36 (2011)] obtained in axisymmetric simulations.

In this paper, we have implemented the Galerkin-collocation method to determine the initial data in two cases of interest for numerical relativity: vacuum axisymmetric Brill waves, and the interaction of axisymmetric Brill waves with a nonrotating black hole, or a distorted black hole. The numerical method combines the main features of the Galerkin and collocation methods which produce very accurate initial data. We have also calculated the Arnowitt-Deser-Misner masses and the location of the apparent horizons of the initial data sets under consideration.

Belgiorno et al. have reported on experiments aiming at the detection of (the analogue of) Hawking radiation using laser filaments [F. Belgiorno et al., Phys. Rev. Lett. 105, 203901 (2010)]. They sent intense focused Bessel pulses into a nonlinear dielectric medium in order to change its refractive index via the Kerr effect and saw creation of photons orthogonal to the direction of travel of the pulses. Since the refractive index change in the pulse generated a “phase horizon” (where the phase velocity of these photons equals the pulse speed), they concluded that they observed the analogue of Hawking radiation. We study this scenario in a model with a phase horizon and a phase velocity very similar to that of their experiment and find that the effective metric does not quite correspond to a black hole. The photons created in this model are not due to the analogue of black hole evaporation but have more similarities to cosmological particle creation. Nevertheless, even this effect cannot explain the observations—unless the pulse has significant small scale structure in both the longitudinal and transverse dimensions.

We considered matter fields composed of a perfect fluid in the static higher-dimensional spherically symmetric asymptotically flat black hole spacetime. The proof of the nonexistence of perfect fluid matter in such a background was provided under the auxiliary condition, which can be interpreted as a relation connecting the stellar mass and the black hole mass in question.

The post-Newtonian theory of motion of celestial bodies and propagation of light was instrumental in conducting the critical experimental tests of general relativity and in building the astronomical ephemerides of celestial bodies in the Solar System with unparalleled precision. The cornerstone of the theory is the postulate that the Solar System is gravitationally isolated from the rest of the Universe and the background spacetime is asymptotically flat. The present article extends this theoretical concept and formulates the principles of celestial dynamics of particles and light moving in the gravitational field of a localized astronomical system embedded to the expanding Friedmann-Lemaître-Robertson-Walker universe. We formulate the precise mathematical concept of the Newtonian limit of Einstein’s field equations in the conformally flat Friedmann-Lemaître-Robertson-Walker spacetime and analyze the geodesic motion of massive particles and light in this limit. We prove that by doing conformal spacetime transformations, one can reduce the equations of motion of particles and light to the classical form of the Newtonian theory. However, the time arguments in the equations of motion of particles and light differ from each other in terms being proportional to the Hubble constant $\mathcal{H}$. This leads to the important conclusion that the equations of light propagation used currently by space navigation centers for fitting range and Doppler-tracking observations of celestial bodies are missing some terms of the cosmological origin that are proportional to the Hubble constant $\mathcal{H}$. We also analyze the effect of the cosmological expansion on motion of electrons in atoms. We prove that the Hubble expansion does not affect the atomic frequencies and hence does not affect the atomic time scale used in the creation of astronomical ephemerides. We derive the cosmological correction to the light travel time equation and argue that its measurement opens an exciting opportunity to determine the local value of the Hubble constant $\mathcal{H}$ in the Solar System independently of cosmological observations.

We argue that from observations alone, only the transverse power spectrum $C_{\ell }(z_1,z_2)$ and the corresponding correlation function $\xi (\theta ,z_1,z_2)$ can be measured and that these contain the full three dimensional information. We determine the two point galaxy correlation function at linear order in perturbation theory. Redshift space distortions are taken into account for arbitrary angular and redshift separations. We discuss the shape of the longitudinal and the transversal correlation functions which are very different from each other and from their real space counterpart. We then go on and suggest how to measure both the Hubble parameter, $H(z)$, and the angular diameter distance, $D_A(z)$, separately from these correlation functions and perform an Alcock-Paczyński test.

Neutron star (NS) merger simulations are conducted for 38 representative microphysical descriptions of high-density matter in order to explore the equation-of-state (EoS) dependence of the postmerger ring-down phase. The formation of a deformed, oscillating, differentially rotating very massive NS is the typical outcome of the coalescence of two stars with $1.35M_{\odot }$ for most candidate EoSs. The oscillations of this object imprint a pronounced peak in the gravitational wave (GW) spectra, which is used to characterize the emission for a given model. The peak frequency of this postmerger GW signal correlates very well with the radii of nonrotating NSs, and thus allows us to constrain the high-density EoS by a GW detection. In the case of $1.35\mathrm{\text{−}}1.35M_{\odot }$ mergers the peak frequency scales particularly well with the radius of an NS with $1.6M_{\odot }$, where the maximum deviation from this correlation is only 60 m for fully microphysical EoSs which are compatible with NS observations. Combined with the uncertainty in the determination of the peak frequency it appears likely that a GW detection can measure the radius of a $1.6M_{\odot }$ NS with an accuracy of about 100–200 m. We also uncover relations of the peak frequency with the radii of nonrotating NSs with $1.35M_{\odot }$ or $1.8M_{\odot }$, with the radius or the central energy density of the maximum-mass Tolman-Oppenheimer-Volkoff configuration, and with the pressure or sound speed at a fiducial rest mass density of about twice the nuclear saturation density. Furthermore, it is found that a determination of the dominant postmerger GW frequency can provide an upper limit for the maximum mass of nonrotating NSs. The effect of variations of the binary setup are investigated and corresponding functional dependences between the peak frequency and radii of nonrotating NSs are derived. With higher total binary masses, correlations are tighter for radii of nonrotating NSs with higher masses. The prospects for a detection of the postmerger GW signal and a determination of the dominant GW frequency are estimated to be in the range of 0.015–1.2 events per year with the upcoming Advanced Laser Interferometer Gravitational Wave Observatory detector.

A class of discrete flavor-symmetry-based models predicts constrained neutrino mass matrix schemes that lead to specific neutrino mass sum rules. One of these implies a lower bound on the effective neutrinoless double beta mass parameter, even for normal hierarchy neutrinos. Here we propose a new model based on the $S_4$ flavor symmetry that leads to the new neutrino mass sum rule and discuss how to generate a nonzero value for the reactor angle ${\theta }_{13}$ indicated by recent experiments, and the resulting correlation with the solar angle ${\theta }_{12}$.

We consider theories where the dark matter particle carries flavor quantum numbers, and has renormalizable contact interactions with the Standard Model fields. The phenomenology of this scenario depends sensitively on whether dark matter carries lepton flavor, quark flavor or its own internal flavor quantum numbers. We show that each of these possibilities is associated with a characteristic type of vertex, has different implications for direct detection experiments and gives rise to distinct collider signatures. We find that the region of parameter space where dark matter has the right abundance to be a thermal relic is in general within reach of current direct detection experiments. We focus on a class of models where dark matter carries tau flavor, and show that the collider signals of these models include events with four or more isolated leptons and missing energy. A full simulation of the signal and backgrounds, including detector effects, shows that in a significant part of parameter space these theories can be discovered above Standard Model backgrounds at the Large Hadron Collider. We also study the extent to which flavor and charge correlations among the final-state leptons allows models of this type to be distinguished from theories where dark matter couples to leptons but does not carry flavor.

We reconsider the strength of the electroweak phase transition in the inert doublet dark matter model, using a quantitatively accurate form for the one-loop finite temperature effective potential, taking into account relevant particle physics and dark matter constraints, focusing on a standard model Higgs mass near 126 GeV, and doing a full scan of the space of otherwise unconstrained couplings. We find that there is a significant (although fine-tuned) space of parameters for achieving an electroweak phase transition sufficiently strong for baryogenesis while satisfying the XENON100 constraints from direct detection and not exceeding the correct thermal relic density. We predict that the dark matter mass should be in the range 60–67 GeV, and we discuss possible LHC signatures of the charged and $CP$-odd Higgs bosons, including an $\sim 10\%$ enhancement of the $h\to \gamma \gamma$ branching ratio.

We investigate the phase transition in cold and dense quark matter in an intuitive way that shares common features of the effective model approaches. We first express the quasiparticle contribution to the thermodynamic potential with the dynamical mass $M$ and then discuss how we can understand the possible first-order phase transition with and without the vector interaction from the saturation curve on the plane of the energy per particle and the density. We next extend our analysis including inhomogeneity and discuss the relation between the order of the phase transition and the saturation curve. We emphasize that the saturation curve is useful to infer qualitative nature of the phase transition even without knowing the explicit solution of the ground state.

We evaluated rates of transversing muons, muon-induced fast neutrons, and production of ${}^{40}\mathrm{Cl}$ and other cosmogenically produced nuclei that pose as potential sources of background to the physics program proposed for an argon-based long baseline neutrino experiment at the Sanford Underground Research Facility, Homestake Mine, in Lead, South Dakota. The Geant4 simulations were carried out with muons and muon-induced neutrons for both the 800 ft level (0.712 km w.e.) and 4850 ft level (4.3 km w.e.). We developed analytic models to independently calculate the ${}^{40}\mathrm{Cl}$ production using the measured muon fluxes at different levels of the Homestake Mine. The muon induced ${}^{40}\mathrm{Cl}$ production rates through stopped muon capture and the muon-induced neutrons and protons via (n, p) and (p, n) reactions were evaluated. We find that the Monte Carlo simulated production rates of ${}^{40}\mathrm{Cl}$ agree well with the predictions from analytic models. A depth-dependent parametrization was developed and benchmarked to the direct analytic models. We conclude that the muon-induced processes will result in large backgrounds to the physics proposed for an argon-based long baseline neutrino experiment at a depth of less than 4.0 km w.e.

In the Randall-Sundrum model, a bulk neutrino field in five-dimensional spacetime can give rise to tiny Dirac masses for neutrinos. In such a scenario, we have computed the contribution of the bulk neutrino field to the anomalous magnetic moment $(g-2{)}_{\mu }$ of the muon. We have computed this contribution in the ’t Hooft-Feynman gauge and have found that the contribution has the right sign to fit the current discrepancy between the experiment and the standard model value of $(g-2{)}_{\mu }$. We have also studied possible constraints on the model parameters by including contributions to $(g-2{)}_{\mu }$ from other sources such as bulk gravitons.

Using the eigenmode of the Dirac operator $\mathrm{D̸}={\gamma }^{\mu }{D}^{\mu }$ in quantum chromodynamics (QCD), we develop a manifestly gauge-covariant expansion and projection of the QCD operators such as the Wilson loop and the Polyakov loop. With this method, we perform a direct analysis of the correlation between confinement and chiral symmetry breaking in lattice QCD Monte Carlo calculation on $6^4$ at $\beta =5.6$. Even after removing the low-lying Dirac modes, which are responsible for chiral symmetry breaking, we find that the Wilson loop obeys the area law, and the slope parameter corresponding to the string tension, or confinement force, is almost unchanged. We find also that the Polyakov loop remains to be almost zero even without the low-lying Dirac modes, which indicates the $Z_3$-unbroken confinement phase. These results indicate that one-to-one correspondence does not hold between confinement and chiral symmetry breaking in QCD.

We calculate the quadratic fluctuations of net baryon number, electric charge and strangeness as well as correlations among these conserved charges in ($2+1$)-flavor lattice QCD at zero chemical potential. Results are obtained using calculations with tree-level improved gauge and the highly improved staggered quark actions with almost physical light and strange quark masses at three different values of the lattice cutoff. Our choice of parameters corresponds to a value of 160 MeV for the lightest pseudoscalar Goldstone mass and a physical value of the kaon mass. The three diagonal charge susceptibilities and the correlations among conserved charges have been extrapolated to the continuum limit in the temperature interval $150\mathrm{MeV}\le T\le 250\mathrm{MeV}$. We compare our results with the hadron resonance gas (HRG) model calculations and find agreement with HRG model results only for temperatures $T\lesssim 150\mathrm{MeV}$. We observe significant deviations in the temperature range $160\mathrm{MeV}\lesssim T\lesssim 170\mathrm{MeV}$ and qualitative differences in the behavior of the three conserved charge sectors. At $T\simeq 160\mathrm{MeV}$ quadratic net baryon number fluctuations in QCD agree with HRG model calculations, while the net electric charge fluctuations in QCD are about 10% smaller and net strangeness fluctuations are about 20% larger. These findings are relevant to the discussion of freeze-out conditions in relativistic heavy ion collisions.

We discuss the advantages of combining the experimental bound on $\mathrm{Br}(B_s\to {\mu }^{+}{\mu }^{-})$ and the measured $\mathrm{Br}(B\to K{\ell }^{+}{\ell }^{-})$ to get the model-independent constraints on physics beyond the Standard Model. Since the two decays give complementary information, one can study not only the absolute values of the Wilson coefficients that are zero in the Standard Model, but also their phases. To identify the sector in which the new physics might appear, information about the shapes of the transverse asymmetries in $B\to K^{*}{\ell }^{+}{\ell }^{-}$ at low $q^2$’s can be particularly useful. We also emphasize the importance of measuring the forward-backward asymmetry in $B\to K{\ell }^{+}{\ell }^{-}$ decay at large $q^2$’s.

The decays $J/\psi \to p\overline{p}$ and $J/\psi \to n\overline{n}$ have been investigated with a sample of $225.2\times {10}^6$ $J/\psi$ events collected with the BESIII detector at the BEPCII $e^{+}{e}^{-}$ collider. The branching fractions are determined to be $\mathcal{B}(J/\psi \to p\overline{p})=(2.112\pm 0.004\pm 0.031)\times {10}^{-3}$ and $\mathcal{B}(J/\psi \to n\overline{n})=(2.07\pm 0.01\pm 0.17)\times {10}^{-3}$. Distributions of the angle $\theta$ between the proton or antineutron and the beam direction are well described by the form $1+\alpha {cos}^2\theta$, and we find $\alpha =0.595\pm 0.012\pm 0.015$ for $J/\psi \to p\overline{p}$ and $\alpha =0.50\pm 0.04\pm 0.21$ for $J/\psi \to n\overline{n}$. Our branching-fraction results suggest a large phase angle between the strong and electromagnetic amplitudes describing the $J/\psi \to N\overline{N}$ decay.