In cosmic ray air showers, the muon lateral separation from the center of the shower is a measure of the transverse momentum that the muon parent acquired in the cosmic ray interaction. IceCube has observed cosmic ray interactions that produce muons laterally separated by up to 400 m from the shower core, a factor of 6 larger distance than previous measurements. These muons originate in high $p_T$ ($>2\mathrm{GeV}/\mathrm{c}$) interactions from the incident cosmic ray, or high-energy secondary interactions. The separation distribution shows a transition to a power law at large values, indicating the presence of a hard $p_T$ component that can be described by perturbative quantum chromodynamics. However, the rates and the zenith angle distributions of these events are not well reproduced with the cosmic ray models tested here, even those that include charm interactions. This discrepancy may be explained by a larger fraction of kaons and charmed particles than is currently incorporated in the simulations.

A lump (2D Skyrmion) can be constructed as a sine-Gordon kink (1D Skyrmion) inside a domain wall in the massive $O(3)$ sigma model. In this paper, we discuss relations between Skyrmions in $2+1$ and $3+1$ dimensions. We first construct a Bogomol’nyi-Prasad-Sommerfield 3D Skyrmion as a lump inside a non-Abelian domain wall in an $O(4)$ sigma model with a potential term admitting two discrete vacua. Next, we construct a conventional 3D Skyrmion as a baby Skyrmion in a non-Abelian domain wall in the Skyrme model with a modified mass term admitting two discrete vacua. We also construct a spinning 3D Skyrmion as a $Q$ lump in the non-Abelian domain wall.

As a toy model of a gapped system, we investigate the entanglement entropy of a massive scalar field in $1+1$ dimensions at nonzero temperature. In a small mass $m$ and temperature $T$ limit, we put upper and lower bounds on the two largest eigenvalues of the covariance matrix used to compute the entanglement entropy. We argue that the entanglement entropy has $e^{-m/T}$ scaling in the limit $T\ll m$. We comment on the relation between our work and the Ryu-Takayanagi proposal for computing the entanglement entropy holographically.

The modified scalar boson propagator due to the presence of a hyperplane semitransparent mirror is computed. From this, the classical interaction between static charges and the mirror is investigated employing delta-like potentials and sources. Although the calculations for hyperplane mirrors are performed in arbitrary dimensions, and in a completely general way, it is shown that the results give rise to the usual image method as a particular case. The interaction between a point-like mirror and a point-like source is also considered in $3+1$ dimensions, where a central $1/R^2$ attractive potential is also obtained as a special case.

This article studies sufficient accuracy criteria of hybrid post-Newtonian (PN) and numerical relativity (NR) waveforms for parameter estimation of strong binary black-hole sources in second-generation ground-based gravitational-wave detectors. We investigate equal-mass nonspinning binaries with a new 33-orbit NR waveform, as well as unequal-mass binaries with mass ratios 2, 3, 4 and 6. For equal masses, the 33-orbit NR waveform allows us to recover previous results and to extend the analysis toward matching at lower frequencies. For unequal masses, the errors between different PN approximants increase with mass ratio. Thus, at 3.5 PN, hybrids for higher-mass-ratio systems would require NR waveforms with many more gravitational-wave cycles to guarantee no adverse impact on parameter estimation. Furthermore, we investigate the potential improvement in hybrid waveforms that can be expected from fourth-order post-Newtonian waveforms and find that knowledge of this fourth post-Newtonian order would significantly improve the accuracy of hybrid waveforms.

We study the near-horizon spacetime for isolated and dynamical trapping horizons (equivalently marginally outer trapped tubes). The metric is expanded relative to an ingoing Gaussian null coordinate and the terms of that expansion are explicitly calculated to second order. For the spacelike case, knowledge of the intrinsic and extrinsic geometry of the (dynamical) horizon is sufficient to determine the near-horizon spacetime, while for the null case (an isolated horizon) more information is needed. In both cases spacetime is allowed to be of arbitrary dimension and the formalism accommodates both general relativity as well as more general field equations. The formalism is demonstrated for two applications. First, spacetime is considered near an isolated horizon and the construction is both checked against the Kerr-Newman solution and compared to the well-known near-horizon limit for stationary extremal black hole spacetimes. Second, spacetime is examined in the vicinity of a slowly evolving horizon and it is demonstrated that there is always an event horizon candidate in this region. The geometry and other properties of this null surface match those of the slowly evolving horizon to leading order and in this approximation the candidate evolves in a locally determined way. This generalizes known results for Vaidya as well as certain spacetimes known from studies of the fluid-gravity correspondence.

A suitable coupling of the inflaton $\phi$ to a vector kinetic term $F^2$ gives frozen and scale invariant vector perturbations. We compute the cosmological perturbations $\zeta$ that result from such coupling by taking into account the classical vector field that unavoidably gets generated at large scales during inflation. This generically results in a too-anisotropic power spectrum of $\zeta$. Specifically, the anisotropy exceeds the 1% level (10% level) if inflation lasts $\sim 5$ e-folds ($\sim 50$ e-folds) more than the minimal amount required to produce the cosmic microwave background modes. This conclusion applies, among others, to the application of this mechanism for magnetogenesis, for anisotropic inflation, and for the generation of anisotropic perturbations at the end of inflation through a waterfall field coupled to the vector (in this case, the unavoidable contribution that we obtain is effective all throughout inflation, and it is independent of the waterfall field). For a tuned duration of inflation, a 1% (10%) anisotropy in the power spectrum corresponds to an anisotropic bispectrum which is enhanced like the local one in the squeezed limit, and with an effective local $f_{\mathrm{NL}}\sim 3(\sim 30)$. More in general, a significant anisotropy of the perturbations may be a natural outcome of all models that sustain higher than 0 spin fields during inflation.

A study of $\mu -\tau$ conversion via the deep inelastic scattering process $\mu N\to \tau X$, with $N$ a nucleon, is performed taking into account the effects from both spin-0 and spin-1 unparticles with lepton flavor violating (LFV) couplings. This process has attracted attention in the past as it may be at the reach of a future neutrino or muon factory. For the model parameters, we use the most recent constraints on the unparticle LFV couplings from the experimental limits on the muon anomalous magnetic moment and the LFV decay $\tau \to 3\mu$, whereas for the unparticle scale ${\Lambda }_{\mathcal{U}}$ and scale dimension $d_{\mathcal{U}}$, we use the bounds obtained from the search for monojets plus missing transverse energy at the LHC. The $\mu N\to \tau X$ cross section is analyzed when the target is a proton, and it is found that the unparticle effects can be larger than the contribution from Higgs exchange in the minimal supersymmetric standard model. We also analyze the behavior of the angular and energy distributions of the emitted tau lepton, which could be used to disentangle among distinct new physics contributions. It is found that, for a beam with an intensity of ${10}^{20}$ muons with an energy around 50 GeV on a ${10}^2\mathrm{gr}/{\mathrm{cm}}^2$ mass target annually, there would be about ${10}^2–{10}^3\mu N\to \tau X$ events per year. The potential background is discussed briefly.

A search for nonresonant new phenomena, originating from either contact interactions or large extra spatial dimensions, has been carried out using events with two isolated electrons or muons. These events, produced at the LHC in proton-proton collisions at $\sqrt{s}=7\mathrm{TeV}$, were recorded by the ATLAS detector. The data sample, collected throughout 2011, corresponds to an integrated luminosity of 4.9 and $5.0{\mathrm{fb}}^{-1}$ in the $e^{+}{e}^{-}$ and ${\mu }^{+}{\mu }^{-}$ channels, respectively. No significant deviations from the Standard Model expectation are observed. Using a Bayesian approach, 95% confidence level lower limits ranging from 9.0 to 13.9 TeV are placed on the energy scale of $\ell \ell qq$ contact interactions in the left-left isoscalar model. Lower limits ranging from 2.4 to 3.9 TeV are also set on the string scale in large extra dimension models. After combining these limits with results from a similar search in the diphoton channel, slightly more stringent limits are obtained.

In many new physics scenarios, the particle content of the Standard Model is extended and the Higgs couplings are modified, sometimes without affecting single Higgs production. We analyze two models with additional quarks. In these models, we compute double Higgs production from gluon fusion exactly at leading order, and present analytical results in the heavy-quark mass approximation. The experimental bounds from precision electroweak measurements and from the measured rate of single Higgs production combine to give significant restrictions for the allowed deviation of the double Higgs production rate from the Standard Model prediction as well as on the branching ratio for the Higgs decay into photons. The two models analyzed eventually present a similar Higgs phenomenology as the Standard Model. We connect this result to the magnitude of the dimension six operators contributing to the gluon-fusion Higgs production.

We calculate the contribution of the higher-twist effects to the large-$p_T$ inclusive single direct photon production cross section in $\pi p$ collisions in the running coupling and frozen coupling approaches within holographic QCD. We obtain the structure of infrared renormalon singularities of the higher-twist subprocess cross section. For a full analysis we compare the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section.

Many neutrino mixing scenarios that have $\mu -\tau$ symmetry with ${\theta }_{13}=0$ are in disagreement with recent experimental results that indicate a nonzero value for ${\theta }_{13}$. We investigate the effect of small perturbations on Majorana mass matrices with $\mu -\tau$ symmetry and derive analytic formulas for the corrections to the mixing angles. We find that since $m_1$ and $m_2$ are nearly degenerate, $\mu -\tau$ symmetry mixing scenarios are able to explain the experimental data with about the same size perturbation for most values of ${\theta }_{12}$. This suggests that the underlying unperturbed mixing need not have ${\theta }_{12}$ close to the experimentally preferred value. One consequence of this is that a new class of models with $\mu -\tau$ symmetry is possible, with unperturbed ${\theta }_{12}$ equal to zero or 90° for arbitrary unperturbed ${\theta }_{13}$.

Hadronic transitions of ${\chi }_{cJ}\to {\eta }_c{\pi }^{+}{\pi }^{-}$ ($J=0$, 1, 2) are searched for using a sample of $1.06\times {10}^8$ $\psi (3686)$ events collected with the BESIII detector at the BEPCII storage ring. The ${\eta }_c$ is reconstructed with $K_S^0{K}^{\pm }{\pi }^{\mp }$ and $K^{+}{K}^{-}{\pi }^0$ final states. No signals are observed in any of the three ${\chi }_{cJ}$ states in either ${\eta }_c$ decay mode. At the 90% confidence level, the upper limits are determined to be $\mathcal{B}({\chi }_{c0}\to {\eta }_c{\pi }^{+}{\pi }^{-})<0.07\%$, $\mathcal{B}({\chi }_{c1}\to {\eta }_c{\pi }^{+}{\pi }^{-})<0.32\%$, and $\mathcal{B}({\chi }_{c2}\to {\eta }_c{\pi }^{+}{\pi }^{-})<0.54\%$. The upper limit of $\mathcal{B}({\chi }_{c1}\to {\eta }_c{\pi }^{+}{\pi }^{-})$ is lower than the existing theoretical prediction by almost an order of magnitude. The branching fractions of ${\chi }_{cJ}\to K_S^0{K}^{\pm }{\pi }^{\mp }{\pi }^{+}{\pi }^{-}$, $K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}{\pi }^0$, $\omega K^{+}{K}^{-}$, and $\varphi {\pi }^{+}{\pi }^{-}{\pi }^0$ $J=0$, 1, 2) are measured for the first time.

We calculate the two-loop level electric and chromoelectric dipole moments of the fermion involving the fermion-sfermion inner loop, gaugino, and Higgsino in the minimal supersymmetric standard model, and analyze the chromoelectric dipole moment with the top-stop inner loop. It is found that this contribution is comparable with, and even dominates, in some situations over the Barr-Zee type diagram generated from the $CP$ violation of the top squark sector in TeV scale supersymmetry breaking.

We study the ($3+1$)-dimensional evolution of non-Abelian plasma instabilities in the presence of a longitudinally expanding background of hard particles using the discretized hard-loop framework. The free streaming background dynamically generates a momentum-space anisotropic distribution which is unstable to the rapid growth of chromomagnetic and chromoelectric fields. These fields produce longitudinal pressure that works to isotropize the system. Extrapolating our results to energies probed in ultrarelativistic heavy-ion collisions we find, however, that a pressure anisotropy persists for a few fm/c. In addition, on time scales relevant to heavy-ion collisions we observe continued growth of plasma instabilities in the strongly non-Abelian regime. Finally, we find that the longitudinal energy spectrum is well described by a Boltzmann distribution with increasing temperature at intermediate time scales.

It is known that cold and hot dark matter imprint opposed effects on the cosmological observables; naturally, it is often thought that they should be made of different kinds of particles. We point out, however, that a Bose-Einstein condensate could be the source of both components. In this framework, the mass and temperature constraints on hot dark matter contain fundamental information of cold dark matter. We discuss two scenarios: a gas made of bosons and a gas made of boson-antiboson pairs. We obtain constraints on the bosonic dark matter parameters from cosmological data and test the idea by probing the condition on the critical temperature of condensation, including a forecast for the Planck mission. We find that the bosonic dark matter picture is consistent with data in the boson scenario, while the boson-antiboson scenario might be increasingly interesting for future data surveys.

In order to understand the so-called decoupling solution for gluon and ghost propagators in QCD, we give a nonperturbative construction of a massive vector field describing a non-Abelian massive spin-one particle, which has the correct physical degrees of freedom and is invariant under a modified Becchi-Rouet-Stora-Tyutin transformation, in a massive Yang-Mills model without the Higgs field, i.e., the Curci-Ferrari model. The resulting non-Abelian massive vector boson field is written by using a nonlinear but local transformation from the original fields in the Curci-Ferrari model. As an application, we write down a local mass term for the Yang-Mills field and a dimension-two condensate, which are exactly invariant under the modified Becchi-Rouet-Stora-Tyutin transformation, Lorentz transformation, and color rotation.

We show that supersymmetric “dark force” models with gravity mediation are viable. To this end, we analyze a simple string-inspired supersymmetric hidden sector model that interacts with the visible sector via kinetic mixing of a light Abelian gauge boson with the hypercharge. We include all induced interactions with the visible sector such as neutralino mass mixing and the Higgs portal term. We perform a detailed parameter space scan comparing the produced dark matter relic abundance and direct-detection cross sections to current experiments.

We examine the Neveu Shwarz-Neveu Shwarz corrections to the type II supergravity given by Gross and Sloan, under the linear T-duality transformations. We show that the gravity and the B-field couplings are invariant under off-shell T-duality, whereas the dilaton couplings are invariant under on-shell T-duality. Requiring the compatibility of the dilaton couplings with off-shell T-duality as a guiding principle, we extend them to include the appropriate Ricci curvature and the divergence of the B-field strength.

We investigate combined effects of topology and boundaries on the vacuum expectation value (VEV) of the fermionic current in the space with an arbitrary number of toroidally compactified dimensions. As a geometry of boundaries we consider two parallel plates on which the fermion field obeys bag boundary conditions. Along the compact dimensions, periodicity conditions are imposed with arbitrary phases. In addition, the presence of a constant gauge field is assumed. The nontrivial topology gives rise to an Aharonov-Bohm effect for the fermionic current induced by the gauge field. It is shown that the VEV of the charge density vanishes and the current density has nonzero expectation values for the components along compact dimensions only. The latter are periodic odd functions of the magnetic flux with the period equal to the flux quantum. In the region between the plates, the VEV of the fermionic current is decomposed into pure topological, single plate, and interference parts. For a massless field the single plate part vanishes and the interference part is distributed uniformly. The corresponding results are generalized for conformally flat spacetimes. Applications of the general formulas to finite-length carbon nanotubes are given within the framework of the Dirac model for quasiparticles in graphene. In the absence of the magnetic flux, two sublattices of the honeycomb graphene lattice yield opposite contributions and the fermionic current vanishes. A magnetic flux through the cross section of the nanotube breaks the symmetry, allowing the current to flow along the compact dimension.