The proposed NEWS apparatus, a spherical detector with a small central electrode sensor operating as a proportional counter, promises to explore new swaths of the direct detection parameter space in the GeV and sub-GeV dark matter particle mass range by employing very light nuclear targets, such as H and He, and by taking advantage of a very low (sub-keV) energy threshold. Here we discuss and study two example classes of dark matter models that will be tested with NEWS: GeV-scale millicharged dark matter, and a GeV-Dirac Fermion dark matter model with a light (MeV-GeV) scalar or vector mediator, and indicate the physical regions of parameter space the experiment can probe.

The resonance-continuum interference is usually neglected when the width of a resonance is small compared to the resonance mass. We reexamine this standard by studying the interference effects in high-resolution decay channels, $\gamma \gamma$ and $ZZ$, of the heavy Higgs boson $H$ in nearly aligned two-Higgs-doublet models. For the $H$ with a sub-percent width-to-mass ratio, we find that, in the parameter space where the LHC 14 TeV $ZZ$ resonance search can be sensitive, the interference effects can modify the $ZZ$ signal rate by $\mathcal{O}(10)\%$ and the exclusion reach by $\mathcal{O}(10)\mathrm{GeV}$. In other parameter space where the $ZZ$ or $\gamma \gamma$ signal rate is smaller, the LHC 14 TeV reach is absent, but a resonance shape can be much more dramatically changed. In particular, the $\gamma \gamma$ signal rate can change by $\mathcal{O}(100)\%$. Relevant to such parameter space, we suggest variables that can characterize a general resonance shape. We also illustrate the relevance of the width on the interference by adding nonstandard decay modes of the heavy Higgs boson.

We probe effects of the partial chiral symmetry restoration to the mass of heavy-light mesons in a constituent quark model by changing the constituent quark mass of the light quark. Due to the competing effect between the quark mass and the linearly rising potential, whose contribution to the energy increases as the quark mass decreases, the heavy-light meson mass has a minimum value near the constituent quark mass typically used in the vacuum. Hence, the meson mass increases as one decreases the constituent quark mass consistent with recent QCD sum rule analyses, which show an increasing $D$ meson mass as the chiral order parameter decreases.

We find, by an appropriate extension of the standard holographic superconductor setup, static bulk solutions which describe holographic duals to non-Abelian vortices. In the core of these vortices, a scalar field condenses, breaking a non-Abelian global symmetry, which leads to additional zero modes called orientational moduli. These moduli appear in the bulk as Goldstone bosons associated to the condensation of a neutral scalar field.

We consider a model of a holographic braneworld universe in which a cosmological fluid occupies a $3+1$-dimensional brane located at the boundary of the asymptotic anti-de Sitter bulk. We combine the $\mathrm{AdS}/\mathrm{CFT}$ correspondence and the second Randall-Sundrum (RSII) model to establish a relationship between the RSII braneworld cosmology and the boundary metric induced by the time dependent bulk geometry. In the framework of the Friedmann-Robertson-Walker cosmology, we discuss some physically interesting scenarios involving the RSII and holographic braneworlds.

Using the linear $T$-dual Ward identity associated with the NS-NS B-field or two Neveu-Schwarz B-fields (NSNS) gauge transformations, some Ramond-Ramond (RR) couplings on ${\mathrm{D}}_p$-branes have been found at order $O({\alpha }^{\prime 2})$. We examine the $C^{(p-1)}$ couplings with the $S$-matrix elements of one RR, one graviton and one antisymmetric B-field vertex operator. We find the consistency of $T$-dual $S$-matrix elements and explicit results of scattering string amplitude and show that the string amplitude reproduces these couplings as well as some other couplings. This illustration is found for $C^{(p-3)}$ couplings in the literature, which is extended to the $C^{(p-1)}$ couplings in this paper.

The “long” indecomposable $\mathcal{N}=2$, $d=1$ multiplet $(\mathbf{2},\mathbf{4},\mathbf{2})$ defined in B. Assel et al. [J. High Energy Phys. 07 (2015) 043] as a deformation of the pair of chiral multiplets $(\mathbf{2},\mathbf{2},\mathbf{0})$ and $(\mathbf{0},\mathbf{2},\mathbf{2})$ by a number of the mass-dimension parameters is described in the superfield approach. We present its most general superfield and component actions as well as a generalization to the case with the superfields of the opposite Grassmann parities and dimensionless deformation parameter. We show that the long $\mathcal{N}=2$, $d=1$ multiplets are naturally embedded into the chiral $SU(2|1)$, $d=1$ superfields having nonzero external spins with respect to $SU(2)\subset SU(2|1)$. A superfield with spin $s$ contains $2s$ long multiplets and two short multiplets $(\mathbf{2},\mathbf{2},\mathbf{0})$ and $(\mathbf{0},\mathbf{2},\mathbf{2})$. Two possible $\mathcal{N}=4$, $d=1$ generalizations of the $\mathcal{N}=2$ long multiplet in the superfield approach are also proposed.

This is an extensive work to our previous paper [S. Li and T. Jia, Matrix model and holographic baryons in the D0-D4 background, Phys. Rev. D 92, 046007 (2015)] that studied the D0-D4/D8 holographic system. We compute the three-body force for baryons with the D0-D4/D8 matrix model derived in [S. Li and T. Jia, Matrix model and holographic baryons in the D0-D4 background, Phys. Rev. D 92, 046007 (2015)] with considering the nonzero QCD vacuum. We obtain the three-body force at short distances but modified by the appearance of the smeared D0-branes, i.e., considering the effects from the nontrivial QCD vacuum. We first test our matrix model in the case of ’t Hooft instanton and then in two more realistic cases: (1) three-neutrons with averaged spins and (2) proton-proton-neutron (or proton-neutron-proton). The three-body potential vanishes in the former case while in the two latter cases it is positive, i.e., repulsive and makes sense only if the constraint for stable baryonic state is satisfied. We require all the baryons in our computation aligned on a line. These may indicate that the cases in dense states of neutrons such as in neutron stars, Helium-3 or Tritium nucleus all with the nontrivial QCD vacuum.

Stable non-Abelian vortices, which are color magnetic flux tubes as well as superfluid vortices, are present in the color-flavor locked phase of dense quark matter with diquark condensations. We calculate the Aharanov-Bohm phases of charged particles, that is, electrons, muons, and color-flavor locked mesons made of tetraquarks around a non-Abelian vortex.

We study novel types of contributions to the partition function of the Maxwell system defined on a small compact manifold. These contributions, often not addressed in the perturbative treatment with physical photons, emerge as a result of tunneling transitions between topologically distinct but physically identical vacuum winding states. These new terms give an extra contribution to the Casimir pressure, yet to be measured. We argue that this effect is highly sensitive to a small external electric field, which should be contrasted with the conventional Casimir effect, where the vacuum photons are essentially unaffected by any external field. Furthermore, photons will be emitted from the vacuum in response to a time-dependent electric field, similar to the dynamical Casimir effect in which real particles are radiated from the vacuum due to the time-dependent boundary conditions. We also propose an experimental setup using a quantum LC circuit to detect this novel effect. We expect physical electric charges to appear on the capacitor plates when the system dimension is such that coherent Aharonov-Bohm phases can be maintained over macroscopically large distances.

We consider the Skyrme model with the addition of extra scalar potentials that decrease the classical binding energies of the Skyrmions to about the 3% level—without altering the pion mass—if we insist on keeping platonic symmetries that are usually possessed by Skyrmions. A side effect of the potentials under consideration is the smaller size of the 1-Skyrmion resulting in a smaller moment of inertia and in turn a larger spin contribution to the energy upon semiclassical quantization. After taking into account the quantum contributions we find total binding energies at the 6% level.

We present a set of one-loop integral coefficient relations in QCD. The unitarity method is useful for exposing one-loop amplitudes in terms of tree amplitudes. The coefficient relations are induced by tree-level Bern-Carrasco-Johansson amplitude relations. We provide examples for box, triangle, and bubble coefficients. These relations reduce the total number of independent coefficients needed to calculate one-loop QCD amplitudes.

We investigate homogeneous cosmological models with perfect-fluid sources in the framework of the Hořava-Lifshitz model for quantum gravity. We show that the Hamiltonian constraint of such spacetimes can be rewritten as the Cardy formula for the entropy in conformal field theory. The Cardy entropy is shown to depend explicitly on the value of the Hořava parameter $\lambda$ so that it can be interpreted as determining the entropy and the gravitational interaction of the theory. Moreover, we show that Verlinde’s Pythagorean representation of the Hamiltonian constraint is also valid in the case of homogeneous Hořava-Lifshitz spacetimes. We interpret these results as a further indication of a deep relationship between gravity, thermodynamics and holography in the quantum regime.

We compare the initial value formulation of the low-energy limit of (nonprojectable) Hořava gravity to that of Einstein-æther theory when the æther is assumed to be hypersurface orthogonal at the level of the field equations. This comparison clearly highlights a crucial difference in the causal structure of the two theories at the nonperturbative level: in Hořava gravity evolution equations include an elliptic equation that is not a constraint relating initial data but needs to be imposed on each slice of the foliation. This feature is absent in Einstein-æther theory. We discuss its physical significance in Hořava gravity. We also focus on spherical symmetry, and we revisit existing collapse simulations in Einstein-æther theory. We argue that they have likely already uncovered the dynamical formation of a universal horizon and that they can act as evidence that this horizon is indeed a Cauchy horizon in Hořava gravity.

In this paper we present 3D numerical relativity simulations of thick accretion disks around tilted Kerr black holes. We investigate the evolution of three different initial disk models with a range of initial black hole spin magnitudes and tilt angles. For all the disk-to-black hole mass ratios considered (0.044–0.16) we observe significant black hole precession and nutation during the evolution. This indicates that for such mass ratios, neglecting the self-gravity of the disks by evolving them in a fixed background black hole spacetime is not justified. We find that the two more massive models are unstable against the Papaloizou-Pringle (PP) instability and that those PP-unstable models remain unstable for all initial spins and tilt angles considered, showing that the development of the instability is a very robust feature of such PP-unstable disks. Our lightest model, which is the most astrophysically favorable outcome of mergers of binary compact objects, is stable. The tilt between the black hole spin and the disk is strongly modulated during the growth of the PP instability, causing a partial global realignment of black hole spin and disk angular momentum in the most massive model with constant specific angular momentum $l$. For the model with nonconstant $l$-profile we observe a long-lived $m=1$ nonaxisymmetric structure which shows strong oscillations of the tilt angle in the inner regions of the disk. This effect might be connected to the development of Kozai-Lidov oscillations. Our simulations also confirm earlier findings that the development of the PP instability causes the long-term emission of large amplitude gravitational waves, predominantly for the $l=m=2$ multipole mode. The imprint of the black hole (BH) precession on the gravitational waves from tilted BH-torus systems remains an interesting open issue that would require significantly longer simulations than those presented in this paper.

Dark Matter particles with inelastic interactions are ubiquitous in extensions of the Standard Model, yet remain challenging to fully probe with existing strategies. We propose a series of powerful searches at hadron and lepton colliders that are sensitive to inelastic dark matter dynamics. In representative models featuring either a massive dark photon or a magnetic dipole interaction, we find that the LHC and BABAR could offer strong sensitivity to the thermal relic dark matter parameter space for dark matter masses between $\sim 100\mathrm{MeV}$ and 100 GeV and fractional mass-splittings above the percent level; future searches at Belle II with a dedicated monophoton trigger could also offer sensitivity to thermal relic scenarios with masses below a few GeV. Thermal scenarios with either larger masses or splittings are largely ruled out; lower masses remain viable yet may be accessible with other search strategies.

Recently Graham, Kaplan and Rajendran proposed cosmological relaxation as a mechanism for generating a hierarchically small Higgs vacuum expectation value. Inspired by this we collect some thoughts on steps towards a solution to the electroweak hierarchy problem and apply them to the original model of cosmological relaxation [Phys. Rev. Lett. 115, 221801 (2015)]. To do so, we study the dynamics of the model and determine the relation between the fundamental input parameters and the electroweak vacuum expectation value. Depending on the input parameters the model exhibits three qualitatively different regimes, two of which allow for hierarchically small Higgs vacuum expectation values. One leads to standard electroweak symmetry breaking whereas in the other regime electroweak symmetry is mainly broken by a Higgs source term. While the latter is not acceptable in a model based on the QCD axion, in non-QCD models this may lead to new and interesting signatures in Higgs observables. Overall, we confirm that cosmological relaxation can successfully give rise to a hierarchically small Higgs vacuum expectation value if (at least) one model parameter is chosen sufficiently small. However, we find that the required level of tuning for achieving this hierarchy in relaxation models can be much more severe than in the Standard Model.

In [V. Salzano, M. P. Dąbrowski, and R. Lazkoz, Phys. Rev. Lett. 114, 101304 (2015)] a new method to measure the speed of light through baryon acoustic oscillations was introduced. Here, we describe in much more detail the theoretical basis of that method and its implementation, and we give some newly updated results about its application to forecast data. In particular, we show that SKA will be able to detect a 1% variation (if any) in the speed of light at the $3\sigma$ level. Smaller signals will be hardly detectable by already-planned future galaxy surveys, but we give indications of what sensitivity requirements a survey should fulfill in order to be successful.

Gravitational waves are propagating undulations in the spacetime fabric, which interact very weakly with their environment. In cosmology, gravitational-wave distortions are produced by most of the inflationary scenarios and their anticipated detection should open a new window to the early Universe. Motivated by the relative lack of studies on the potential implications of gravitational radiation for the large-scale structure of the Universe, we consider its coupling to density perturbations during the postrecombination era. We do so by assuming an Einstein–de Sitter background cosmology and by employing a second-order perturbation study. At this perturbative level and on superhorizon scales, we find that gravitational radiation adds a distinct and faster growing mode to the standard linear solution for the density contrast. Given the expected weakness of cosmological gravitational waves, however, the effect of the new mode is currently subdominant and it could start becoming noticeable only in the far future. Nevertheless, this still raises the intriguing possibility that the late-time evolution of large-scale density perturbations may be dictated by the long-range (the Weyl), rather than the local (the Ricci) component of the gravitational field.