This work is devoted to the construction of slowly rotating neutron stars in the framework of the nonminimal derivative coupling sector of Horndeski theory. We match the large radius expansion of spherically symmetric solutions with cosmological solutions, and we find that the most viable model has only one free parameter. Then, by using several tabulated and realistic equations of state, we establish numerically the upper bound for this parameter in order to construct neutron stars in the slow rotation approximation with the maximal mass observed today. We finally study the surface redshift and the inertia of these objects and compare them with known data.

The first detection of a gravitational wave (GW) has been achieved by two detectors of the advanced LIGO. Routine detections of GW events from various GW sources are expected in the coming decades. Although the first signal was statistically significant, we expect to see numerous low signal-to-noise ratio (SNR) events with which we may be able to learn various aspects of the Universe that have yet to be unveiled. On the other hand, instrumental glitches due to nonstationarity and/or a non-Gaussian tail of detector noise distribution prevent us from confidently identifying true but low SNR GW signals out of instrumental noise. Thus, to make the best use of data from GW detectors, it is important to establish a method to safely distinguish true GW signals from false signals due to instrumental noises. For this purpose, we urgently need to understand characteristics of detector noises, since the nonstationarity and non-Gaussianity inherent in detector outputs are known to increase false detections of signals. Focusing on identifying the non-Gaussian noise components, this paper introduces a new measure for characterizing the non-Gaussian noise components using the parameter $\nu$ which characterizes the weight of tail in a Student-t distribution. A confidence interval is reported on the extent to which detector noise deviates from Gaussianity. Our method revealed stationary and transient deterioration of Gaussianity in LIGO S5 data.

We consider the possibility that the recently observed excess in the diphoton invariant mass spectrum around 750 GeV is due to two narrow scalars. We demonstrate that there is no need to introduce invisible decay modes to enlarge the widths as long as the two scalars exhibit an appropriate mass splitting. Nevertheless, we investigate the possible connection of these two scalars to the dark matter in a toy model with a Majorana fermionic dark-matter candidate. We explore how large the widths of the two scalar widths could be, taking into account various constraints from collider and dark-matter experiments. Introducing two scalars alleviates the tension between the diphoton production and dark-matter constraints.

We interpret the 750 GeV diphoton excess recently found in the 13 TeV LHC data as a singlet scalar in an extra dimensional model, where one extra dimension is introduced. In the model, the scalar couples to multiple vectorlike fermions, which are just the Kaluza-Klein modes of SM fermions. Mediated by the loops of these vectorlike fermions, the $\varphi$ effective couplings to gluons and photons can be significantly large. Therefore, it is quite easy to obtain an observed cross section for the diphoton excess. We also calculate the cross sections for other decay channels of $\varphi$, and find that this interpretation can evade the bounds from the 8 TeV LHC data.

It is shown that two physical phenomena are important for high excitations: (i) the screening of the universal gluon-exchange potential and (ii) the flattening of the confining potential owing to creation of quark loops, and both effects are determined quantitatively. Taking the first effect into account, we predict the masses of the ground states with $l=0$, 1, 2 in agreement with experiment. The flattening effect ensures the observed linear behavior of the radial Regge trajectories $M^2(n)=m_0^2+n_r{\mu }^2{\mathrm{GeV}}^2$, where the slope ${\mu }^2$ is very sensitive to the parameter $\gamma$, which determines the weakening of the string tension $\sigma (r)$ at large distances. For the $\rho$ trajectory the linear behavior starts with $n_r=1$ and the values ${\mu }^2=1.40(2){\mathrm{GeV}}^2$ for $\gamma =0.40$ and ${\mu }^2=1.34(1){\mathrm{GeV}}^2$ for $\gamma =0.45$ are obtained. For the excited states the leptonic widths ${\mathrm{\Gamma }}_{\mathrm{ee}}(\rho (775))=7.0(3)\mathrm{keV}$, ${\mathrm{\Gamma }}_{\mathrm{ee}}(\rho (1450))=1.7(1)\mathrm{keV}$, ${\mathrm{\Gamma }}_{\mathrm{ee}}(\rho (1900))=1.0(1)\mathrm{keV}$, ${\mathrm{\Gamma }}_{\mathrm{ee}}(\rho (2150))=0.7(1)\mathrm{keV}$, and ${\mathrm{\Gamma }}_{\mathrm{ee}}(1{{}^{3}D}_1)=0.26(5)\mathrm{keV}$ are calculated, if these states are considered as purely $q\overline{q}$ states. The width ${\mathrm{\Gamma }}_{\mathrm{ee}}(\rho (1700))$ increases if $\rho (1700)$ is mixed with the $2{{}^{3}S}_1$ state, giving for a mixing angle $\theta =21°$ almost equal widths: ${\mathrm{\Gamma }}_{\mathrm{ee}}(\rho (1700))=0.75(6)\mathrm{keV}$ and ${\mathrm{\Gamma }}_{\mathrm{ee}}(1450)=1.0(1)\mathrm{keV}$.

We describe the pure spinor string in the ${\mathrm{AdS}}_5\times S^5$ using unconstrained matrices first used by Roiban and Siegel for the Green-Schwarz superstring.

We point out that the Cartan geometry known as the second-order conformal structure provides a natural differential geometric framework underlying gauge theories of conformal gravity. We are concerned with two theories: the first one is the associated Yang-Mills-like Lagrangian, while the second, inspired by [1], is a slightly more general one that relaxes the conformal Cartan geometry. The corresponding gauge symmetry is treated within the Becchi-Rouet-Stora-Tyutin language. We show that the Weyl gauge potential is a spurious degree of freedom, analogous to a Stueckelberg field, that can be eliminated through the dressing field method. We derive sets of field equations for both the studied Lagrangians. For the second one, they constrain the gauge field to be the “normal conformal Cartan connection.’’Finally, we provide in a Lagrangian framework a justification of the identification, in dimension 4, of the Bach tensor with the Yang-Mills current of the normal conformal Cartan connection, as proved in [2].

Using a $C$-metric-type ansatz, we obtain an exact solution to conformal gravity coupled to a Maxwell electromagnetic field. The solution resembles a $C$-metric spacetime carrying an electromagnetic charge. The metric is cast in a factorized form which allows us to study the domain structure of its static coordinate regions. This metric reduces to the well-known Mannheim-Kazanas metric under an appropriate limiting procedure, and also reduces to the (anti)de Sitter $C$-metric of Einstein gravity for a particular choice of parameters.

The sensitivity of the gravitational-wave detector KAGRA, presently under construction, will be limited by quantum noise in a large fraction of its spectrum. The most promising technique to increase the detector sensitivity is the injection of squeezed states of light, where the squeezing angle is dynamically rotated by a Fabry-Pérot filter cavity. One of the main issues in the filter cavity design and realization is the optical losses due to the mirror surface imperfections. In this work we present a study of the specifications for the mirrors to be used in a 300 m filter cavity for the KAGRA detector. A prototype of the cavity will be constructed at the National Astronomical Observatory of Japan, inside the infrastructure of the former TAMA interferometer. We also discuss the potential improvement of the KAGRA sensitivity, based on a model of various realistic sources of losses and their influence on the squeezing amplitude.

Ultrahigh energy neutrinos are interesting messenger particles since, if detected, they can transmit exclusive information about ultrahigh energy processes in the Universe. These particles, with energies above ${10}^{16}\mathrm{eV}$, interact very rarely. Therefore, detectors that instrument several gigatons of matter are needed to discover them. The ARA detector is currently being constructed at the South Pole. It is designed to use the Askaryan effect, the emission of radio waves from neutrino-induced cascades in the South Pole ice, to detect neutrino interactions at very high energies. With antennas distributed among 37 widely separated stations in the ice, such interactions can be observed in a volume of several hundred cubic kilometers. Currently three deep ARA stations are deployed in the ice, of which two have been taking data since the beginning of 2013. In this article, the ARA detector “as built” and calibrations are described. Data reduction methods used to distinguish the rare radio signals from overwhelming backgrounds of thermal and anthropogenic origin are presented. Using data from only two stations over a short exposure time of 10 months, a neutrino flux limit of $1.5\times {10}^{-6}\mathrm{GeV}/{\mathrm{cm}}^2/\mathrm{s}/\mathrm{sr}$ is calculated for a particle energy of ${10}^{18}\mathrm{eV}$, which offers promise for the full ARA detector.

To explain quark and lepton masses and mixing angles, one has to extend the standard model, and the usual practice is to put the quarks and leptons into irreducible representations of discrete groups. We argue that discrete flavor symmetries (and their concomitant problems) can be avoided if we extend the gauge group. In the framework of SU(12) we give explicit examples of models having varying degrees of predictability obtained by scanning over groups and representations and identifying cases with operators contributing to mass and mixing matrices that need little fine-tuning of prefactors. Fitting with quark and lepton masses run to the GUT scale and known mixing angles allows us to make predictions for the neutrino masses and hierarchy, the octant of the atmospheric mixing angle, leptonic $CP$ violation, Majorana phases, and the effective mass observed in neutrinoless double beta decay.

In this work, dispersion relations of ${\pi }^0$ and ${\pi }^{\pm }$ have been studied in vacuum in the limit of a weak external magnetic field using a phenomenological pion-nucleon $(\pi N)$ Lagrangian. For our purpose, we have calculated the results up to one loop order in self-energy diagrams with the pseudoscalar $(\mathrm{PS})$ and pseudovector $(\mathrm{PV})$ pion-nucleon interactions. By assuming a weak external magnetic field, it is seen that the effective mass of the pion gets explicit magnetic field dependence, and it is modified significantly for the case of PS coupling. However, for the PV coupling, only a modest increase in the effective mass is observed. These modified dispersion relations due to the presence of the external field can have substantial influence in the phenomenological aspect of the mesons, both in the context of neutron stars as well as in relativistic heavy ion collisions.

We study beam-transverse and normal single-spin asymmetry for electron-proton inelastic scattering in the resonance region for the case where a pion is observed in the final state. There is no beam single-spin asymmetry if the observed particle has single-photon exchange as its only interaction, but this is naturally circumvented when one observes a strongly interacting final state particle. The asymmetries are not large as there is an electron mass divided by momentum transfer suppression. We present results for the cases where the final electron and a pion are both observed, with asymmetries of order tens of ppm, and where only a final pion is observed, with asymmetries of order 1 ppm.

We consider extensions of the Standard Model in which a spontaneously broken global chiral Peccei-Quinn (PQ) symmetry arises as an accidental symmetry of an exact $Z_N$ symmetry. For $N=9$ or 10, this symmetry can protect the accion—the Nambu-Goldstone boson arising from the spontaneous breaking of the accidental PQ symmetry—against semiclassical gravity effects, thus suppressing gravitational corrections to the effective potential, while it can at the same time provide for the small explicit symmetry breaking term needed to make models with domain wall number $N_{\mathrm{DW}}>1$, such as the popular Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model ($N_{\mathrm{DW}}=6$), cosmologically viable even in the case where spontaneous PQ symmetry breaking occurred after inflation. We find that $N=10$ DFSZ accions with mass $m_A\approx 3.5–4.2\mathrm{meV}$ can account for cold dark matter and simultaneously explain the hints for anomalous cooling of white dwarfs. The proposed helioscope International Axion Observatory—being sensitive to solar DFSZ accions with mass above a few meV—will decisively test this scenario.

The mass formula for black holes can be formally expressed in terms of a Noether charge surface integral plus a suitable volume integral, for any gravitational theory. The integrals can be constructed as an application of Wald’s formalism. We apply this formalism to compute the mass and the Smarr formula for static Lovelock black holes. Finally, we propose a new prescription for Wald’s entropy in the case of Lovelock black holes, which takes into account topological contributions to the entropy functional.

We propose a practical parametrization for the line shapes of near-threshold states compatible with all requirements of unitarity and analyticity. The coupled-channel system underlying the proposed parametrization includes bare poles and an arbitrary number of elastic and inelastic channels treated fully nonperturbatively. The resulting formulas are general enough to be used for a simultaneous analysis of the data in all available production and decay channels of the (system of) state(s) under consideration for a quite wide class of reactions. As an example, we fit the experimental data currently available for several decay channels for the charged $Z_b^{(\prime )}$ states in the spectrum of bottomonia and find a good overall description of the data. We find the present data to be consistent with the $Z_b(10610)$ as a virtual state and with the $Z_b(10650)$ as a resonance, both residing very close to the $B{\overline{B}}^{*}$ and $B^{*}{\overline{B}}^{*}$ threshold, respectively.

Recent advances in soft-collinear effective theory with Glauber gluons have led to the development of a new method that gives a unified description of inclusive hadron production in reactions with nucleons and heavy nuclei. We show how this approach, based on the generalization of the DGLAP evolution equations to include final-state medium-induced parton shower corrections for large $Q^2$ processes, can be combined with initial-state effects for applications to jet quenching phenomenology. We demonstrate that the traditional parton energy loss calculations can be regarded as a special soft-gluon emission limit of the general QCD evolution framework. We present phenomenological comparison of the ${\mathrm{SCET}}_{\mathrm{G}}$-based results on the suppression of inclusive charged hadron and neutral pion production in $\sqrt{s_{\mathrm{NN}}}=2.76\mathrm{TeV}$ lead-lead collisions at the Large Hadron Collider to experimental data. We also show theoretical predictions for the upcoming $\sqrt{s_{\mathrm{NN}}}\simeq 5.1\mathrm{TeV}$ $\mathrm{Pb}+\mathrm{Pb}$ run at the LHC.

We use next-to-leading order in perturbation theory to investigate the effects of a finite isospin density on the thermodynamics of cold strongly interacting matter. Our results include nonzero quark masses and are compared to lattice data.