We construct cylindrical, traversable wormholes with finite radii by taking into account the cut-and-paste procedure for the case of cosmic string manifolds with a positive cosmological constant. Under reasonable assumptions about the equation of state of the matter located at the shell, we find that the wormhole throat undergoes a monotonous evolution provided it moves at a constant velocity. In order to explore the dynamical nonlinear behavior of the wormhole throat, we consider that the matter of the shell is supported by anisotropic Chaplygin gas, anti-Chaplygin gas, or a mixture of Chaplygin and anti-Chaplygin gases, implying that wormholes could suffer an accelerated expansion or contraction, but that oscillatory behavior seems to be forbidden.

In a general single field inflationary model, we consider the effects of long wavelength scalar fluctuations on the effective expansion rate and equation of state seen by a class of free-falling observers, using a physical gauge invariant formulation. In a previous work we showed that for a free massive inflaton no backreaction is observed within some constraints. In this paper we extend the validity of our previous results to the case of an arbitrary self-interacting inflation potential, working to second order in cosmological perturbation theory and to all order in slow-roll approximation. For these general inflationary models, we also show the equivalence of the free-falling observers to the ones comoving with the inflaton field.

We have directly measured the energy threshold and efficiency for bubble nucleation from iodine recoils in a ${\mathrm{CF}}_3\mathrm{I}$ bubble chamber in the energy range of interest for a dark matter search. These interactions cannot be probed by standard neutron calibration methods, so we develop a new technique by observing the elastic scattering of $12\mathrm{GeV}/c$ negative pions. The pions are tracked with a silicon pixel telescope and the reconstructed scattering angle provides a measure of the nuclear recoil kinetic energy. The bubble chamber was operated with a nominal threshold of $(13.6\pm 0.6)\mathrm{keV}$. Interpretation of the results depends on the response to fluorine and carbon recoils, but in general we find agreement with the predictions of the classical bubble-nucleation theory. This measurement confirms the applicability of ${\mathrm{CF}}_3\mathrm{I}$ as a target for spin-independent dark matter interactions and represents a novel technique for calibration of superheated fluid detectors.

The CDMS II experiment has observed three events which may have arisen from weakly interacting massive particle (WIMP) dark matter (DM) with mass of order 9 GeV colliding with nuclei. Although the implied WIMP parameter region seems to be excluded by limits from the XENON experiments, it is interesting that most of this tension can go away if the WIMP-nucleon interaction violates isospin. This motivates us to explore some of the implications for models in which a real gauge-singlet scalar particle, the darkon, serves as the WIMP, taking into account the recent discovery of a Higgs boson at the LHC and Planck determination of the DM relic density. In the simplest scenario, involving only the standard model plus a darkon, the Higgs boson is largely invisible due to its decay into a pair of darkons having the WIMP mass suggested by CDMS II and hence cannot be identified with the one found at the LHC. We find, on the other hand, that a two-Higgs-doublet model supplemented with a darkon has ample parameter space to accommodate well both the new potential DM hint from CDMS II and the Higgs data from the LHC, whether or not the darkon-nucleon interaction conserves isospin.

An analysis of radiative decays of the neutrinos ${\nu }_j\to {\nu }_l\gamma$ is discussed in minimal supersymmetric standard model extensions with a vector like lepton generation. Specifically we compute neutrino decays arising from the exchange of charginos and charged sleptons where the photon is emitted by the charged particle in the loop. It is shown that while the lifetime of the neutrino decay in the Standard Model is $\sim {10}^{43}\mathrm{yrs}$ for a neutrino mass of 50 meV, the current lower limit from experiment from the analysis of the Cosmic Infrared Background is $\sim {10}^{12}\mathrm{yrs}$ and thus beyond the reach of experiment in the foreseeable future. However, in the extensions with a vectorlike lepton generation the lifetime for the decays can be as low as $\sim {10}^{12}–{10}^{14}\mathrm{yrs}$ and thus within reach of future improved experiments. The effect of $CP$ phases on the neutrino lifetime is also analyzed. It is shown that while both the magnetic and the electric transition dipole moments contribute to the neutrino lifetime, often the electric dipole moment dominates even for moderate size $CP$ phases.

Results from the nuclear recoil calibration of the XENON100 dark matter detector installed underground at the Laboratori Nazionali del Gran Sasso, Italy are presented. Data from measurements with an external $\mathrm{AmB}{}^{241}\mathrm{e}$ neutron source are compared with a detailed Monte Carlo simulation which is used to extract the energy-dependent charge-yield ${\mathcal{Q}}_{\mathrm{y}}$ and relative scintillation efficiency ${\mathcal{L}}_{\mathrm{eff}}$. A very good level of absolute spectral matching is achieved in both observable signal channels—scintillation S1 and ionization S2—along with agreement in the two-dimensional particle discrimination space. The results confirm the validity of the derived signal acceptance in earlier reported dark matter searches of the XENON100 experiment.

We study ${\chi }_{c1}(2P)$-inclusive hadroproduction at next-to-leading-order (NLO), both in ${\alpha }_s$ and $v^2$, within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD), including the color-singlet ${}^{3}P_1^{[1]}$ and color-octet ${}^{3}S_1^{[8]}$ $c\overline{c}$ Fock states as well as the mixing of the latter with the ${}^{3}D_1^{[8]}$ state. Assuming the recently discovered $X(3872)$ hadron to be the $J^{PC}=1^{++}$ charmonium state ${\chi }_{c1}(2P)$, we perform a fit to the cross sections measured by the CDF, CMS, and LHCb Collaborations. We obtain either an unacceptably high value of ${\chi }^2$, a value of $|R_{2P}^{\prime }(0)|$ incompatible with well-established potential models, or an intolerable violation of the NRQCD velocity rules. We thus conclude that NLO NRQCD is inconsistent with the hypothesis $X(3872)\equiv {\chi }_{c1}(2P)$.

In this paper, we investigate the conservation laws of different types of particles in theories with a universal gravity/matter coupling. The result brings new insight about previous studies on universal gravity/matter theories. Especially, the paper demonstrates that, for perfect fluids, there is an equivalence between the assumption ${\mathcal{L}}_m=-ϵ$, where $ϵ$ is the total energy density, and the assumption that the matter fluid current is conserved [${\nabla }_{\sigma }(\rho u^{\sigma })=0$, where $\rho$ is the rest mass density]. However, the main result is given in the general case in which one does not make any assumption on the conservation of the matter fluid current.

In this paper we consider spherically symmetric general fluids with heat flux, motivated by causal thermodynamics, and give the appropriate set of conditions that define separating shells, defining the divide between expansion and collapse. To do so we add the new requirement that heat flux and its evolution vanish at the separating surface. We extend previous works with a fully nonlinear analysis in the $1+3$ splitting and present gauge-invariant results. The definition of the separating surface is inspired by the conservation of the Misner-Sharp mass and is obtained by generalizing the Tolman-Oppenheimer-Volkoff equilibrium and turnaround conditions. We emphasize the nonlocal character of these conditions as found in previous works and discuss connections to the phenomena of spacetime cracking and thermal peeling.

We consider a five-dimensional brane world model with a single brane which is distinct from the well known Randall-Sundrum model. We discuss the similarities and differences between our brane model and the Randall-Sundrum brane model. In particular we focus on the localization of five-dimensional fields with different spins—spin 0, spin $1/2$, and spin 1—to the brane, and a self-consistent mass-generation mechanism. We find that the brane model studied here has different (and in some cases superior) localization properties for fields/particles with different spins to the brane, as compared to the original five-dimensional brane models. In addition this alternative five-dimensional brane model exhibits a self-generation mechanism which recalls the self-consistent approach of Nambu and Jona-Lasinio.

We find that relative locality, a recently proposed Planck-scale deformation of special relativity, suffers from the existence of causal loops. A simple and general construction of such on-shell loop processes is studied. We then show that even in one of the weakest deformations of the Poincaré group in relative locality, causality can be violated.

Making use of the conformal positive energy theorem, we prove the uniqueness of four-dimensional static electrically charged black holes being the solution of Chern-Simons modified gravity equations of motion. We assume that black hole spacetime contains an asymptotically flat spacelike hypersurface with compact interior and nondegenerate components of the event horizon.

We derive the expressions for canonical energy, momentum, and angular momentum for multiple metric theories. We prove that although the metric fields are generally interacting, the total energy is the sum of conserved energies corresponding to each metric. A positive energy theorem is given as a result. In addition, we present an Hamiltonian formalism for a subgroup of multimetric theories.

Gravitational lens models with negative convergence (surface mass density projected onto the lens plane) inspired by modified gravity theories, exotic matter, and energy have been recently discussed in such a way that a static and spherically symmetric modified spacetime metric depends on the inverse distance to the power of positive $n$ ($n=1$ for Schwarzschild metric, $n=2$ for Ellis wormhole) in the weak-field approximation [T. Kitamura, K. Nakajima, and H. Asada, Phys. Rev. D 87, 027501 (2013)], and it has been shown that demagnification of images could occur for $n>1$ lens models associated with exotic matter (and energy), though they cause the gravitational pull on light rays. The present paper considers gravitational lensing shear by the demagnifying lens models and other models such as negative-mass compact objects causing the gravitational repulsion on light rays like a concave lens. It is shown that images by the lens models for the gravitational pull are tangentially elongated, whereas those by the repulsive ones are radially distorted. This feature of lensed image shapes may be used for searching (or constraining) localized exotic matter or energy with gravitational lensing surveys. It is suggested also that an underdense region such as a cosmic void might produce radially elongated images of background galaxies rather than tangential ones.

The statistical properties of the primordial perturbations contain clues about their origins. Although the Planck collaboration has recently obtained tight constraints on primordial non-Gaussianity from cosmic microwave background measurements, it is still worthwhile to mine upcoming data sets in an effort to place independent or competitive limits. The ionized bubbles that formed at redshift $z\sim 6–20$ during the epoch of reionization were seeded by primordial overdensities, and so the statistics of the ionization field at high redshift are related to the statistics of the primordial field. Here we model the effect of primordial non-Gaussianity on the reionization field. The epoch and duration of reionization are affected, as are the sizes of the ionized bubbles, but these changes are degenerate with variations in the properties of the ionizing sources and the surrounding intergalactic medium. A more promising signature is the power spectrum of the spatial fluctuations in the ionization field, which may be probed by upcoming 21 cm surveys. This has the expected $1/k^2$ dependence on large scales, characteristic of a biased tracer of the matter field. We project how well upcoming 21 cm observations will be able to disentangle this signal from foreground contamination. Although foreground cleaning inevitably removes the large-scale modes most impacted by primordial non-Gaussianity, we find that primordial non-Gaussianity can be separated from foreground contamination for a narrow range of length scales. In principle, futuristic redshifted 21 cm surveys may allow constraints competitive with Planck.

Supersymmetry and string theory suggest the existence of light moduli. Their presence, or absence, controls the realization of supersymmetry at low energies. If there are no such fields, or if all such fields are fixed in a supersymmetric fashion, the conventional thermal production of lightest supersymmetric particle dark matter is possible, as is an anomaly-mediated (“mini-split”) spectrum. On the other hand, the axion solution to the strong $CP$ problem is not operative, and slow roll inflation appears difficult to implement. If there are light moduli, a mini-split spectrum is less generic, weakly interacting dark matter appears atypical, and the supersymmetry scale is likely tens of TeV or higher.

The rise of the cosmic ray positron fraction with energy, as first observed with high confidence by PAMELA, implies that a large flux of high energy positrons has been recently (or is being currently) injected into the local volume of the Milky Way. With the new and much more precise measurement of the positron fraction recently provided by the Alpha Magnetic Spectrometer (AMS), we revisit the question of the origin of these high energy positrons. We find that while some dark matter models (annihilating directly to electrons or muons) no longer appear to be capable of accommodating these data, other models in which $\sim 1–3\mathrm{TeV}$ dark matter particles annihilate to unstable intermediate states could still be responsible for the observed signal. Nearby pulsars also remain capable of explaining the observed positron fraction. Future measurements of the positron fraction by the AMS Collaboration (using a larger data set) combined with their anticipated measurements of various cosmic ray secondary-to-primary ratios may enable us to further discriminate between these remaining scenarios.

The ongoing global effort to detect gravitational waves continues to push the limits of precision measurement while aiming to provide a new tool for understanding both astrophysics and fundamental physics. Squeezed states of light offer a proven means of increasing the sensitivity of gravitational wave detectors, potentially increasing the rate at which astrophysical sources are detected by more than 1 order of magnitude. Since radiation pressure noise plays an important role in advanced detectors, frequency-dependent squeezing will be required. In this paper we propose a practical approach to producing frequency-dependent squeezing for Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and similar interferometric gravitational wave detectors. This work focuses on “realistic filter cavities” in the sense that optical losses in the filter cavity and squeezed light source consistent with current technology are considered. The filter cavity solution proposed for Advanced LIGO is “practical” in that it considers the nonquantum noise and readout scheme of the interferometer and a potential implementation geometry in the Advanced LIGO vacuum envelope.

In universal extra dimension (UED) models with one compactified extra dimension, a ${\mathbf{Z}}_2$ symmetry, termed KK parity, ensures the stability of the lightest Kaluza-Klein particle (LKP) which could be a viable dark matter candidate. This symmetry leads to two fixed points. In nonminimal versions of UED boundary-localized (kinetic or mass) terms (BLT) for different fields are included at these fixed points and KK parity may be violated. However, BLTs with same strength at both points induce a new ${\mathbf{Z}}_2$ symmetry which restores the stability of the LKP. We show that the BLTs serve to relax the bounds set on the compactification scale in UED by the observed dark matter relic density. At the same time, the precision of the dark matter measurements severely correlates the BLT parameters of gauge bosons and fermions. Depending on the parameter values, the LKP can be chosen to be the level-1 photon, which is essentially the $B^{(1)}$, or the level-1 $Z$ boson, basically the $W_3^{(1)}$. We find that in the latter case the relic density is too small if the $W_3^{(1)}$ has a mass $\sim 1\mathrm{TeV}$. We also explore the prospects of direct detection of an LKP which matches the observed dark matter relic density.

We perform a study of the stability of $R$-parity-conserving vacua of a constrained version of the minimal supersymmetric model with a gauged $U(1{)}_{B-L}$ which can conserve $R$ parity, using homotopy continuation to find all the extrema of the tree-level potential, for which we also calculated the one-loop corrections. While we find that a majority of the points in the parameter space preserve $R$ parity, we find that a significant portion of points which naïvely have phenomenologically acceptable vacua which conserve $R$ parity actually have deeper vacua which break $R$ parity through sneutrino VEVs. We investigate under what conditions the deeper $R$-parity-violating vacua appear. We find that while previous exploratory work was broadly correct in some of its qualitative conclusions, we disagree in detail.