We have determined the dispersion relation of a neutrino test particle propagating in the cosmic neutrino background. Describing the relic neutrinos and antineutrinos from the hot big bang as a dense medium, a matter potential or refractive index is obtained. The vacuum neutrino mixing angles are unchanged, but the energy of each mass state is modified. Using a matrix in the space of neutrino species, the induced potential is decomposed into a part which produces signatures in beta-decay experiments and another part which modifies neutrino oscillations. The low temperature of the relic neutrinos makes a direct detection extremely challenging. From a different point of view, the identified refractive effects of the cosmic neutrino background constitute an ultralow background for future experimental studies of nonvanishing Lorentz violation in the neutrino sector.

The ATLAS experiment has performed extensive searches for the electroweak production of charginos, neutralinos, and staus. This article summarizes and extends the search for electroweak supersymmetry with new analyses targeting scenarios not covered by previously published searches. New searches use vector-boson fusion production, initial-state radiation jets, and low-momentum lepton final states, as well as multivariate analysis techniques to improve the sensitivity to scenarios with small mass splittings and low-production cross sections. Results are based on $20{\mathrm{fb}}^{-1}$ of proton-proton collision data at $\sqrt{s}=8\mathrm{TeV}$ recorded with the ATLAS experiment at the Large Hadron Collider. No significant excess beyond Standard Model expectations is observed. The new and existing searches are combined and interpreted in terms of 95% confidence-level exclusion limits in simplified models, where a single production process and decay mode is assumed, as well as within phenomenological supersymmetric models.

($2+1$)-dimensional Abelian gauged $CP(2)$ model with a self-interaction potential is considered. It is shown that there are topological solitons in this model. The magnetic flux of these solitons can be either quantized or nonquantized. Properties of the topological soliton with quantized magnetic flux are investigated as well as properties of the topological soliton with nonquantized magnetic flux. A comparative analysis of the properties is performed for the topological solitons of both types. Solutions of the model field equations are obtained numerically for the topological solitons of both types. The dependencies on the model parameters are presented for the energy and magnetic flux of the solitons. The stability of the topological solitons of both types to the decay into solitons with smaller topological charges is studied numerically. Possible generalizations of the investigated topological solitons are discussed.

Clock synchronization between the ground and satellites is a fundamental issue in future quantum telecommunication, navigation, and global positioning systems. Here, we propose a scheme of near-Earth orbit satellite-based quantum clock synchronization with atmospheric dispersion cancellation by taking into account the spacetime background of the Earth. Two frequency entangled pulses are employed to synchronize two clocks, one at a ground station and the other at a satellite. The time discrepancy of the two clocks is introduced into the pulses by moving mirrors and is extracted by measuring the coincidence rate of the pulses in the interferometer. We find that the pulses are distorted due to effects of gravity when they propagate between the Earth and the satellite, resulting in remarkably affected coincidence rates. We also find that the precision of the clock synchronization is sensitive to the source parameters and the altitude of the satellite. The scheme provides a solution for satellite-based quantum clock synchronization with high precision, which can be realized, in principle, with current technology.

In this paper, we compute the decay rates of massless scalar waves excited by a star circularly orbiting around the nonextremal (general) and extremal Banados-Teitelboim-Zanelli (BTZ) black holes. These decay rates are compared with the corresponding quantities computed in the corresponding dual conformal field theories. We find that matches are achieved in both cases.

In this paper, we investigate the problem of localization and the Hodge duality for a $q$-form field on a $p$-brane with codimension one. By a general Kaluza-Klein (KK) decomposition without gauge fixing, we obtain two Schrödinger-like equations for two types of KK modes of the bulk $q$-form field, which determine the localization and mass spectra of these KK modes. It is found that there are two types of zero modes (the 0-level modes): a $q$-form zero mode and a ($q-1$)-form one, which cannot be localized on the brane at the same time. For the $n$-level KK modes, there are two interacting KK modes, a massive $q$-form KK mode and a massless ($q-1$)-form one. By analyzing gauge invariance of the effective action and choosing a gauge condition, the $n$-level massive $q$-form KK mode decouples from the $n$-level massless ($q-1$)-form one. It is also found that the Hodge duality in the bulk naturally becomes two dualities on the brane. The first one is the Hodge duality between a $q$-form zero mode and a $(p-q-1)$-form one, or between a ($q-1$)-form zero mode and a $(p-q)$-form one. The second duality is between two group KK modes: one is an $n$-level massive $q$-form KK mode with mass $m_n$ and an $n$-level massless ($q-1$)-form mode; another is an $n$-level $(p-q)$-form one with the same mass $m_n$ and an $n$-level massless $(p-q-1)$-form mode. Because of the dualities, the effective field theories on the brane for the KK modes of the two dual bulk form fields are physically equivalent.

We propose a way to distinguish a compact stellar object, whose size is very close to its Schwarzschild radius, from the collapsing stars. Namely, we show that massive fields in the vicinity of a very compact stellar object have discrete energy levels. (These levels are different from the standard nonrelativistic ones present in Coulomb-type potentials and from the quasinormal modes.) At the same time, we show that there are no such discrete levels for massive fields in the vicinity of a collapsing star.

We study the effect of a mass term in the spontaneous scalarization of neutron stars, for a wide range of scalar field parameters and neutron star equations of state. Even though massless scalars have been the focus of interest in spontaneous scalarization so far, recent observations of binary systems rule out most of their interesting parameter space. We point out that adding a mass term to the scalar field potential is a natural extension to the model that avoids these observational bounds if the Compton wavelength of the scalar is small compared to the binary separation. Our model is formally similar to the asymmetron scenario recently introduced in application to cosmology, though here we are interested in consequences for neutron stars and thus consider a mass term that does not modify the geometry on cosmological scales. We review the allowed values for the mass and scalarization parameters in the theory given current binary system observations and black hole spin measurements. We show that within the allowed ranges, spontaneous scalarization can have nonperturbative, strong effects that may lead to observable signatures in binary neutron star or black hole–neutron star mergers, or even in isolated neutron stars.

We introduce a fully coherent method for searching for gravitational wave signals generated by the merger of black hole and/or neutron star binaries. This extends the coherent analysis previously developed and used for targeted gravitational wave searches to an all-sky, all-time search. We apply the search to one month of data taken during the fifth science run of the LIGO detectors. We demonstrate an increase in sensitivity of 25% over the coincidence search, which is commensurate with expectations. Finally, we discuss prospects for implementing and running a coherent search for gravitational wave signals from binary coalescence in the advanced gravitational wave detector data.

For the warm dark matter (WDM) candidates the momentum distribution of particles becomes important, since it can be probed with observations of Lyman-$\alpha$ forest structures and confronted with coarse grained phase space density in galaxy clusters. We recall the calculation [M. Kaplinghat, Phys. Rev. D 72, 063510 (2005)] of the spectrum in the case of dark matter nonthermal production in decays of heavy particles emphasizing the inherent applicability conditions, which are rather restrictive and sometimes ignored in literature. The cold part of the spectrum requires special care when WDM is considered.

An exact analytical model of the process of collision and nonlinear interaction of gravitational and/or electromagnetic soliton waves and strong nonsoliton electromagnetic traveling waves of arbitrary profile propagating in the expanding universe (the symmetric Kasner spacetime) is presented. In contrast to intuitive expectations that rather strong traveling waves can destroy the soliton, it occurs that the soliton survives during its interaction with electromagnetic waves of arbitrary amplitude and profile, but its parameters begin to evolve under the influence of this interaction. If a traveling electromagnetic wave possesses a finite duration, the soliton parameters after interaction take constant values again, but these values in general are different from those before the interaction. Based on exact solutions of the Einstein-Maxwell equations, our model demonstrates a series of nonlinear phenomena, such as (a) creation of gravitational waves in the collision of two electromagnetic waves, (b) creation of electromagnetic soliton waves in the collision of a gravitational soliton with traveling electromagnetic waves, (c) scattering of a part of a soliton wave in the direction of propagation of a traveling electromagnetic wave, and (d) quasiperiodic oscillating character of fields in the wave interaction region and multiple mutual transformations of gravitational and electromagnetic waves in this region. The figures illustrate these features of nonlinear wave interactions in general relativity.

The tentative hints for a diphoton resonance at a mass of $\sim 750\mathrm{GeV}$ from the ATLAS and CMS experiments at the LHC may be interpreted as first contact with a “dark” sector with a spontaneously broken conformal symmetry. The implied TeV scale of the dark sector may be motivated by the interaction strength required to accommodate a viable thermal relic dark matter (DM) candidate. We model the conformal dynamics using a Randall-Sundrum-type five-dimensional geometry whose IR boundary is identified with the dynamics of the composite dark sector, while the Standard Model (SM) matter content resides on the UV boundary, corresponding to “elementary” fields. We allow the gauge fields to reside in the five-dimensional bulk, which can be minimally chosen to be $SU(3{)}_c\times U(1{)}_Y$. The “dark” radion is identified as the putative 750 GeV resonance. Heavy vectorlike fermions, often invoked to explain the diphoton excess, are not explicitly present in our model and are not predicted to appear in the spectrum of TeV scale states. Our minimal setup favors scalar DM of $\mathcal{O}(\mathrm{TeV})$ mass. A generic expectation in this scenario, suggested by DM considerations, is the appearance of vector bosons at $\sim$ few TeV, corresponding to the gluon and hypercharge Kaluza-Klein (KK) modes that couple to UV boundary states with strengths that are suppressed uniformly compared to their SM values. Our analysis suggests that these KK modes could be within the reach of the LHC in the coming years.

Recently interest in grand unification scale baryogenesis has been resurrected due to the observation that $B$-violating dimension seven operators that arise in grand unified theories that also violate $B-L$ produce baryon asymmetry that cannot be wiped out by sphaleron processes. While a general analysis of such higher dimensional operators from a bottom up approach exists in the literature, a full analysis of them derived from grand unification does not exist. In this paper we present a complete analysis of $B-L=-2$ operators within a realistic $\mathsf{S}\mathsf{O}(\mathsf{10})$ grand unification where the doublet-triplet splitting is automatic via a missing partner mechanism. Specifically we compute all allowed dimension five, dimension seven and dimension nine operators arising from matter-Higgs interactions. The relative strength of all the allowed $B-L=-2$ operators is given. Such interactions are useful in the study of neutrino masses, baryogenesis, proton decay and $n-\overline{n}$ oscillations within a common realistic grand unification framework.

We show that, when boosted to the infinite momentum frame, the quark and gluon orbital angular momentum operators defined in the nucleon spin sum rule of Chen et al. are the same as those whose matrix elements correspond to the moments of generalized transverse momentum distributions. This completes the connection between the infinite momentum limit of each term in that sum rule and experimentally measurable observables. We also show that these orbital angular momentum operators can be defined locally and discuss the strategies of calculating them in lattice QCD.

It was recently derived that the QCD running coupling is a function of the magnetic field strength under the strong magnetic field approximation. Inspired by this progress and based on the self-consistent solutions of gap equations, the properties of two-flavor and three-flavor quark matter are studied in the framework of the Nambu–Jona-Lasinio model with a magnetic-field-dependent running coupling. We find that the dynamical quark masses as functions of the magnetic field strength are not monotonous in the fully chirally broken phase. Furthermore, the stability of magnetized quark matter with the running coupling is enhanced by lowering the free energy per baryon, which is expected to be more stable than that of the conventional constant coupling case. It is concluded that the magnetized strange quark matter described by running coupling can be absolutely stable.

Recent results from neutrino experiments show evidence for light sterile neutrinos which do not have any Standard Model interactions. In this work, we study the hidden interaction of sterile neutrinos with an “MeV-scale” gauge boson (the ${\nu }_s\mathrm{HI}$ model) with mass $M_X$ and leptonic coupling $g_l^{\prime }$. By performing an analysis on the ${\nu }_s\mathrm{HI}$ model using the data of the MINOS neutrino experiment, we find that the values above $G_X/G_F=92.4$ are excluded by more than $2\sigma$ C.L., where $G_F$ is the Fermi constant and $G_X$ is the field strength of the ${\nu }_s\mathrm{HI}$ model. Using this model, we can also probe other new physics scenarios. We find that the region allowed by the $(g-2{)}_{\mu }$ discrepancy is entirely ruled out for $M_X\lesssim 100\mathrm{MeV}$. Finally, the secret interaction of sterile neutrinos has been to solve a conflict between the sterile neutrinos and cosmology. It is shown here that such an interaction is excluded by MINOS for $g_s^{\prime }>1.6\times {10}^{-2}$. This exclusion, however, does depend on the value of $g_l^{\prime }$.

The axial form factor plays a crucial role in quasielastic neutrino-nucleus scattering, but the error of the theoretical cross section due to uncertainties of $G_A$ remains to be established. Conversely, the extraction of $G_A$ from the neutrino nucleus cross section suffers from large systematic errors due to nuclear model dependencies, while the use of single-parameter dipole fits underestimates the errors and prevents an identification of the relevant kinematics for this determination. We propose to use a generalized axial-vector-meson dominance in conjunction with large-$N_c$ and high-energy QCD constraints to model the nucleon axial form factor, as well as the half-width rule as an a priori uncertainty estimate. The minimal hadronic ansatz comprises the sum of two monopoles corresponding to the lightest axial-vector mesons being coupled to the axial current. The parameters of the resulting axial form factor are the masses and widths of the two axial mesons as obtained from the averaged Particle Data Group values. By applying the half-width rule in a Monte Carlo simulation, a distribution of theoretical predictions can then be generated for the neutrino-nucleus quasielastic cross section. We test the model by applying it to the $({\nu }_{\mu },\mu )$ quasielastic cross section from ${}^{12}\mathrm{C}$ for the kinematics of the MiniBooNE experiment. The resulting predictions have no free parameters. We find that the relativistic Fermi gas model globally reproduces the experimental data, giving ${\chi }^2/\#\text{bins}=0.81$. A $Q^2$-dependent error analysis of the neutrino data shows that the uncertainties in the axial form factor $G_A(Q^2)$ are comparable to the ones induced by the a priori half-width rule. We identify the most sensitive region to be in the range $0.2\lesssim Q^2\lesssim 0.6{\mathrm{GeV}}^2$.

We search for a light Higgs boson $A^0$ in the fully reconstructed decay chain of $J/\psi \to \gamma A^0$, $A^0\to {\mu }^{+}{\mu }^{-}$ using $(225.0\pm 2.8)\times {10}^6$ $J/\psi$ events collected by the BESIII experiment. The $A^0$ is a hypothetical $CP$-odd light Higgs boson predicted by many extensions of the Standard Model including two spin-0 doublets plus an extra singlet. We find no evidence for $A^0$ production and set 90% confidence-level upper limits on the product branching fraction $\mathcal{B}(J/\psi \to \gamma A^0)\times \mathcal{B}(A^0\to {\mu }^{+}{\mu }^{-})$ in the range of $(2.8–495.3)\times {10}^{-8}$ for $0.212\le m_{A^0}\le 3.0\mathrm{GeV}/c^2$. The new limits are five times below our previous results, and the nature of the $A^0$ is constrained to be mostly singlet.

We demonstrate that a substantial part of the present uncertainties in model predictions for the average maximum depth of cosmic ray-induced extensive air showers is related to very high energy pion-air collisions. Our analysis shows that the position of the maximum of the muon production profile in air showers is strongly sensitive to the properties of such interactions. Therefore, the measurements of the maximal muon production depth by cosmic ray experiments provide a unique opportunity to constrain the treatment of pion-air interactions at very high energies and to reduce thereby model-related uncertainties for the shower maximum depth.

The $B^{+}\to D^{+}{K}^{+}{\pi }^{-}$ decay is observed in a data sample corresponding to $3.0{\mathrm{fb}}^{-1}$ of $pp$ collision data recorded by the LHCb experiment during 2011 and 2012. The signal significance is $8\sigma$ and the branching fraction is measured to be $\mathcal{B}(B^{+}\to D^{+}{K}^{+}{\pi }^{-})=(5.31\pm 0.90\pm 0.48\pm 0.35)\times {10}^{-6}$, where the uncertainties are statistical, systematic and due to the normalization mode $B^{+}\to D^{-}{K}^{+}{\pi }^{+}$, respectively. The Dalitz plot appears to be dominated by broad structures. Angular distributions are exploited to search for quasi-two-body contributions from $B^{+}\to D_2^{*}(2460{)}^0{K}^{+}$ and $B^{+}\to D^{+}{K}^{*}(892{)}^0$ decays. No significant signals are observed and upper limits are set on their branching fractions.