We calculate asymmetric neutrino absorption and scattering cross sections on hot and dense magnetized neutron star matter, including hyperons in fully relativistic mean-field theory. The absorption/scattering cross sections are suppressed/enhanced incoherently in the direction of the magnetic field $\mathbf{B}=B\widehat{z}$. The asymmetry is 2–4% at the matter density ${\rho }_0\le {\rho }_B\le 3{\rho }_0$ and temperature $T\le 40\mathrm{MeV}$ for $B=2\times {10}^{17}\mathrm{G}$. This asymmetry is comparable to the effects owing to parity violation or asymmetric magnetic field topology proposed for the origin of pulsar kicks.

We discuss exclusive elastic double diffractive axial-vector ${\chi }_c(1^{+})$ and tensor ${\chi }_c(2^{+})$ mesons production for different meson polarizations in proton-(anti)proton collisions at the Tevatron energy. The amplitude for the process is derived within the $k_t$-factorization approach using unintegrated gluon distributions. Differential cross sections for different ${\chi }_c$ polarizations are calculated. Angular distributions of $J/\psi$ meson from the radiative ${\chi }_c(1^{+},2^{+})$ decays are derived. Prospects for experimental selection of different spin states of ${\chi }_c$ mesons are discussed.

The littlest Higgs model with $T$ parity has new flavor-changing couplings with the standard model quarks, which do not suffer strong constraints from electroweak precision data. So these flavor-changing interactions may enhance the cross sections of some flavor-changing neutral-current processes. In this work, we study the flavor-changing top-charm associated productions via the $e^{-}\gamma$ collision at the ILC. We find that the cross sections are sensitive to the mirror quark masses. With reasonable values of the parameters, the cross sections may reach the detectable level and provide useful information about the relevant parameters in the littlest Higgs model with $T$ parity, especially in setting an upper limit on the mirror quark masses.

The decay width and mass of the $D_{s1}(2536{)}^{+}$ meson are measured via the decay channel $D_{s1}^{+}\to D^{*+}{K}_S^0$ using $385{\mathrm{fb}}^{-1}$ of data recorded with the BABAR detector in the vicinity of the ${\rm Y}(4S)$ resonance at the PEP-II asymmetric-energy electron-positron collider. The result for the decay width is $\Gamma (D_{s1}^{+})=0.92\pm 0.03(\mathrm{stat}.)\pm 0.04(\mathrm{syst}.)\mathrm{MeV}$. For the mass, a value of $m(D_{s1}^{+})=2535.08\pm 0.01(\mathrm{stat}.)\pm 0.15(\mathrm{syst}.)\mathrm{MeV}/c^2$ is obtained. The mass difference between the $D_{s1}^{+}$ and the $D^{*+}$ is measured to be $m(D_{s1}^{+})-m(D^{*+})=524.83\pm 0.01(\mathrm{stat}.)\pm 0.04(\mathrm{syst}.)\mathrm{MeV}/c^2$, representing a significant improvement compared to the current world average. The unnatural spin-parity assignment for the $D_{s1}^{+}$ meson is confirmed.

A new class of inflation models within the context of G inflation is proposed, in which the standard model Higgs boson can act as an inflaton thanks to Galileon-like nonlinear derivative interaction. The generated primordial density perturbation is shown to be consistent with the present observational data. We also make a general discussion on potential-driven $G$-inflation models, and find a new consistency relation between the tensor-to-scalar ratio $r$ and the tensor spectral index $n_T$, $r=-32\sqrt{6}{n}_T/9$, which is crucial in discriminating the present models from standard inflation with a canonical kinetic term.

A single quantum system, such as the Unruh-DeWitt detector, can be used to determine absolute acceleration by local measurements on a quantum field. To show this, we consider two kinematically indistinguishable scenarios: an inertial observer, Bob, measuring the field of a uniformly accelerated cavity, and his noninertial twin, Rob, accelerating and making measurements in a stationary cavity. We find that these scenarios can be distinguished in the nonrelativistic regime only by measurements on highly excited massive fields, allowing one to detect the noninertialness of the reference frame.

A recent reformulation of the scalar-vector sector of standard electroweak theory (without a Higgs potential), in terms of manifestly $SU(2{)}_W$ gauge-invariant variables, is extended so that all field variables in the action are manifestly free of the residual $U(1{)}_{\mathrm{em}}$ gauge transformations as well. Functional evaluation of the one-loop gauge-free effective Higgs potential is shown to precisely cancel effects due to the local functional measure of the Higgs field found earlier. The implications for the classical interpretation of the Higgs scalar as the dilaton field in a background conformal gravity theory are discussed. The Higgs scalar is shown to radiatively acquire a one-loop vacuum expectation value which gives masses to the $W$ and $Z$ bosons but not to photons, without any notion of “spontaneous gauge symmetry breaking” appearing anywhere. Further, the renormalization scale is fixed in this theory by requiring that $W$ and $Z$ boson masses coincide with their experimentally measured values, thereby precluding any “naturalness” problem usually associated with uncontrolled running of such a scale.

We study the most general case of spherically symmetric vacuum solutions in the framework of the covariant Horava-Lifshitz gravity, for an action that includes all possible higher order terms in curvature which are compatible with power-counting normalizability requirement. We find that solutions can be separated into two main classes: (i) solutions with nonzero radial shift function, and (ii) solutions with zero radial shift function. In the case (ii), spherically symmetric solutions are consistent with observations if we adopt the view of Horava and Melby-Tomson [P. Horava and C. M. Melby-Thompson, Phys. Rev. D 82, 064027 (2010).], according to which the auxiliary field $A$ can be considered as a part of an effective general relativistic metric, which is valid only in the IR limit. On the other hand, in the case (i), consistency with observations implies that the field $A$ should be independent of the spacetime geometry, as the Newtonian potential arises from the nonzero radial shift function. Also, our aim in this paper is to discuss and compare these two alternative but different assumptions for the auxiliary field $A$.

We study the relation between two sets of correlators in interacting quantum field theory on de Sitter space. The first are correlators computed using in-in perturbation theory in the expanding cosmological patch of de Sitter space (also known as the conformal patch, or the Poincaré patch), and for which the free propagators are taken to be those of the free Euclidean vacuum. The second are correlators obtained by analytic continuation from Euclidean de Sitter; i.e., they are correlators in the fully interacting Hartle-Hawking state. We give an analytic argument that these correlators coincide for interacting massive scalar fields with any $m^2>0$. We also verify this result via direct calculation in simple examples. The correspondence holds diagram by diagram, and at any finite value of an appropriate Pauli-Villars regulator mass $M$. Along the way, we note interesting connections between various prescriptions for perturbation theory in general static spacetimes with bifurcate Killing horizons.

We consider tensor-multiscalar representations for several types of modified gravity actions. The first example is the theory with the action representing an arbitrary smooth function of the scalar curvature $R$ and $\square R$, the integrand of the Gauss-Bonnet term and the square of the Weyl tensor. We present a simple procedure leading to an equivalent theory of a space-time metric and four auxiliary scalars and especially discuss the calibration of a cosmological constant and the condition of the existence of de Sitter-like solutions in the case of an empty universe. The condition for obtaining a smaller number of independent scalar fields is derived. The second example is the Eddington-like gravity action. In this case we show, in particular, the equivalence of the theory to general relativity with the cosmological constant term, with or without use of the first-order formalism, and also discuss some possible generalizations.

We treat a model in which tensor perturbations of de Sitter spacetime, represented as a spatially flat model, are modified by the effects of the vacuum fluctuations of a massless conformally invariant field, such as the electromagnetic field. We use the semiclassical theory of gravity with the expectation value of the conformal field stress tensor as a source. We first study the stability of de Sitter spacetime by searching for growing, spatially homogeneous modes, and conclude that it is stable within the limits of validity of the semiclassical theory. We next examine the modification of linearized plane gravity waves by the effects of the quantum stress tensor. We find a correction term which is of the same form as the original wave, but displaced in phase by $\pi /2$, and with an amplitude which depends upon an initial time. The magnitude of this effect is proportional to the change in scale factor after this time. We discuss alternative interpretations of this time, but pay particular attention to the view that this is the beginning of inflation. So long as the energy scale of inflation and the proper frequency of the mode at the beginning of inflation are well below the Planck scale, the fractional correction is small. However, modes which are trans-Planckian at the onset of inflation can undergo a significant correction. The increase in amplitude can potentially have observable consequences through a modification of the power spectrum of tensor perturbations in inflationary cosmology. This enhancement of the power spectrum depends upon the initial time, and is greater for shorter wavelengths.

Continuing work initiated in earlier publications [Yamada, Asada, Phys. Rev. D 82, 104019 (2010); Phys. Rev. D83, 024040 (2011)], we investigate the post-Newtonian effects on Lagrange’s equilateral triangular solution for the three-body problem. For three finite masses, it is found that the equilateral triangular configuration satisfies the post-Newtonian equation of motion in general relativity, if and only if all three masses are equal. When a test mass is included, the equilateral configuration is possible for two cases: (1) one mass is finite and the other two are zero, or (2) two of the masses are finite and equal, and the third one is zero, namely, a symmetric binary with a test mass. The angular velocity of the post-Newtonian equilateral triangular configuration is always smaller than the Newtonian one, provided that the masses and the side length are the same.

We demonstrate how, for an arbitrary number of dimensions, the Galileon actions and their covariant generalizations can be obtained through a standard Kaluza-Klein compactification of higher-dimensional Lovelock gravity. In this setup, the dilaton takes on the role of the Galileon. In addition, such compactifications uncover other more general Galilean actions, producing purely second-order equations in the weak-field limit, now both for the Galileon and the metric perturbations.

The Belinskii, Khalatnikov, and Lifshitz conjecture [V. A. Belinskii, I. M. Khalatnikov, and E. M. Lifshitz, Adv. Phys. 19, 525 (1970)] posits that on approach to a spacelike singularity in general relativity the dynamics are well approximated by “ignoring spatial derivatives in favor of time derivatives.” In A. Ashtekar, A. Henderson, and D. Sloan, Classical Quantum Gravity 26, 052 001 (2009), we examined this idea from within a Hamiltonian framework and provided a new formulation of the conjecture in terms of variables well suited to loop quantum gravity. We now present the details of the analytical part of that investigation. While our motivation came from quantum considerations, thanks to some of its new features, our formulation should be useful also for future analytical and numerical investigations within general relativity.

Using a new parallel computing technique, we have run the largest cosmic string simulations ever performed. Our results confirm the existence of a long transient period where a nonscaling distribution of small loops is produced at lengths depending on the initial correlation scale. As time passes, this initial population gives way to the true scaling regime, where loops of size approximately equal to one-twentieth the horizon distance become a significant component. We observe similar behavior in matter and radiation eras, as well as in flat space. In the matter era, the scaling population of large loops becomes the dominant component; we expect this to eventually happen in the other eras as well.

For the Lagrangian $L=G\ln G$ where $G$ is the Gauss-Bonnet curvature scalar we deduce the field equation and solve it in closed form for 3-flat Friedmann models using a state-finder parametrization. Further we show that among all Lagrangians $F(G)$ this $L$ is the only one not having the form $G^r$ with a real constant $r$ but possessing a scale-invariant field equation. This turns out to be one of its analogies to $f(R)$ theories in two-dimensional space-time. In the appendix, we systematically list several formulas for the decomposition of the Riemann tensor in arbitrary dimensions $n$, which are applied in the main deduction for $n=4$.

Little Higgs models often feature spontaneously broken extra global symmetries, which must also be explicitly broken in order to avoid massless Goldstone modes in the spectrum. We show that a possible conflict with collective symmetry breaking then implies light modes coupled to the Higgs boson, leading to interesting phenomenology. Moreover, spontaneous $CP$ violation is quite generic in such cases, as the explicit breaking may be used to stabilize physical $CP$-odd phases in the vacuum. We demonstrate this in an $\mathrm{SU}(2)\times \mathrm{SU}(2)\times \mathrm{U}(1)$ variant of the littlest Higgs, as well as in an original $\mathrm{SU}(6)/\mathrm{SO}(6)$ model. We show that even a very small explicit breaking may lead to large phases, resulting in new sources of $CP$ violation in this class of models.

Charge conjugation ($C$) and parity ($P$) are exact symmetries at $\theta =\pi$ and $\Theta \equiv \mu /(iT)=\pi$, where $\theta$ is the parameter of the so-called $\theta$ vacuum, $\mu$ is the imaginary quark-number chemical potential and $T$ is the temperature. Spontaneous breakings of these discrete symmetries are investigated by the Polyakov-loop extended Nambu–Jona-Lasinio model. At zero $T$, $P$ symmetry is spontaneously broken while $C$ symmetry is conserved. As $T$ increases, $P$ symmetry is restored just after $C$ symmetry is spontaneously broken, so that either $P$ or $C$ symmetry or both the symmetries are spontaneously broken for any $T$. The chiral-symmetry restoration and the deconfinement transition at $\theta =\Theta =0$ are remnants of the $P$ restoration and the $C$ breaking at $\theta =\Theta =\pi$, respectively.

The Exceptional Supersymmetric (SUSY) Standard Model (${\mathrm{E}}_6\mathrm{SSM}$) predicts three families of Higgs doublets plus three Higgs singlets, where one family develops vacuum expectation values (VEVs), while the remaining two which do not are called Inert. The model can account for the dark matter relic abundance if the two lightest Inert neutralinos, identified as the (next-to) lightest SUSY particles ((N)LSPs), have masses close to half the $Z$ mass. In this case we find that the usual SM-like Higgs boson decays more than 95% of the time into either LSPs or NLSPs. The latter case produces a final state containing two leptons $l^{+}{l}^{-}$ with an invariant mass less than or about 10 GeV. We illustrate this scenario with a set of benchmark points satisfying phenomenological constraints and the WMAP dark matter relic abundance. This scenario also predicts other light Inert chargino and neutralino states below 200 GeV, and large LSP direct detection cross sections close to current limits and observable soon at XENON100.

There is a growing interest in very long baseline neutrino oscillation experimentation using an accelerator produced neutrino beam as a machinery to probe the last three unmeasured neutrino oscillation parameters: the mixing angle ${\theta }_{13}$, the possible $CP$ violating phase ${\delta }_{CP}$ and the mass hierarchy, namely, the sign of $\Delta m_{32}^2$. Water Cherenkov detectors such as IMB, Kamiokande and Super-Kamiokande have shown to be very successful at detecting neutrino interactions. Scaling up this technology may continue to provide the required performance for the next generation of experiments. This report presents the latest effort to demonstrate that a next generation ($>100\mathrm{kton}$) water Cherenkov detector can be used effectively for the rather difficult task of detecting ${\nu }_e$s from the neutrino oscillation ${\nu }_{\mu }\to {\nu }_e$ despite the large expected potential background resulting from ${\pi }^0$s produced via neutral current interactions.