The production of the resonance $X(3823)$, identified as the charmonium ${}^3{D}_2$ state, in the process $e^{+}{e}^{-}\to \pi \pi X(3823)$ has been recently reported by BESIII. Here it is pointed out that this process is fully described, up to one overall coupling constant, in the soft pion limit. An interpretation of the available and possible future data within the discussed theoretical framework may reveal new features of the charmoniumlike states. In particular, the observed relative yield for this process at different energies strongly suggests a very significant enhancement of the amplitude at the charmoniumlike peak near 4.36 GeV.

We address the impact of sterile fermions on the lepton flavor violating decays of quarkonia as well as of the $Z$ boson. We compute the relevant Wilson coefficients and show that the $\mathrm{B}(V\to {\ell }_{\alpha }{\ell }_{\beta })$, where $V=\varphi ,{\psi }^{(n)}$, ${\mathrm{\Upsilon }}^{(n)},Z$ can be significantly enhanced in the case of large sterile fermion masses and a non-negligible active-sterile mixing. We illustrate that feature in a specific minimal realization of the inverse seesaw mechanism, known as (2, 3)-ISS, and in an effective model in which the presence of nonstandard sterile fermions is parametrized by means of one heavy sterile (Majorana) neutrino.

We present a measurement of the $W$-boson-pair production cross section in $p\overline{p}$ collisions at 1.96 TeV center-of-mass energy and the first measurement of the differential cross section as a function of jet multiplicity and leading-jet energy. The $W^{+}{W}^{-}$ cross section is measured in the final state comprising two charged leptons and neutrinos, where either charged lepton can be an electron or a muon. Using data collected by the CDF experiment corresponding to $9.7{\mathrm{fb}}^{-1}$ of integrated luminosity, a total of 3027 collision events consistent with $W^{+}{W}^{-}$ production are observed with an estimated background contribution of $1790\pm 190$ events. The measured total cross section is $\sigma (p\overline{p}\to W^{+}{W}^{-})=14.0\pm 0.6(\text{stat}{)}_{-1.0}^{+1.2}(\text{syst})\pm 0.8(\text{lumi})\mathrm{pb}$, consistent with the standard model prediction.

We give a fermionic Fock space description of embedded entangled qubits. Within this framework the problem of classification of pure state entanglement boils down to the problem of classifying spinors. The usual notion of separable states turns out to be just a special case of the one of pure spinors. By using the notion of single, double and mixed occupancy representation with intertwiners relating them a natural physical interpretation of embedded qubits is found. As an application of these ideas one can make a physical sound meaning of some of the direct sum structures showing up in the context of the so-called black-hole/qubit correspondence. We discuss how the usual invariants for qubits serving as measures of entanglement can be obtained from invariants for spinors in an elegant manner. In particular a detailed case study for recovering the invariants for four-qubits within a spinorial framework is presented. We also observe that reality conditions on complex spinors defining Majorana spinors for embedded qubits boil down to self-conjugate states under the Wootters spin flip operation. Finally we conduct a study on the explicit structure of $\text{Spin}(16,\mathbb{C})$ invariant polynomials related to the structure of possible measures of entanglement for fermionic systems with eight modes. Here we find an algebraically independent generating set of the generalized stochastic local operations and classical communication invariants and calculate their restriction to the dense orbit. We point out the special role the largest exceptional group $E_8$ is playing in these considerations.

The notion of quantum-mechanical completeness is adapted to situations where the only adequate description is in terms of quantum field theory in curved space-times. It is then shown that Schwarzschild black holes, although geodesically incomplete, are quantum complete.

We consider the so-called Hopfield model for the electromagnetic field in a dielectric dispersive medium in a framework in which one allows a space-time dependence of microscopic parameters, aimed at a phenomenological description of a space-time varying dielectric perturbation induced by means of the Kerr effect. We discuss the analogue Hawking effect by introducing a simplified model which avoids some difficulties which characterize in the full Hopfield model, still keeping the same dispersion relation. Our main result is an analytical calculation of the spontaneous thermal emission in the single-branch case, which is provided nonperturbatively for the first time in the framework of dielectric black holes. A universal mechanism for thermality which is shared both by optical black holes and acoustic black holes is also pointed out.

When using incorrect or inaccurate signal models to perform parameter estimation on a gravitational wave signal, biased parameter estimates will in general be obtained. For a single event this bias may be consistent with the posterior, but when considering a population of events this bias becomes evident as a sag below the expected diagonal line of the $P\text{−}P$ plot showing the fraction of signals found within a certain significance level versus that significance level. It would be hoped that recently proposed techniques for accounting for model uncertainties in parameter estimation would, to some extent, alleviate this problem. Here we demonstrate that this is indeed the case. We derive an analytic approximation to the $P\text{−}P$ plot obtained when using an incorrect signal model to perform parameter estimation. This approximation is valid in the limit of high signal-to-noise ratio and nearly correct waveform models. We show how the $P\text{−}P$ plot changes if a Gaussian process likelihood that allows for model errors is used to analyze the data. We demonstrate analytically and using numerical simulations that the bias is always reduced in this way. These results provide a way to quantify bias in inference on populations and demonstrate the importance of utilizing methods to mitigate this bias.

In this paper we study the classical dynamics of long strings in ${\mathrm{AdS}}_3$, generalizing our previous study, arXiv:1410.3424, to rotating strings and BTZ black holes. As in the nonrotating case, BTZ black holes are generated in the large tension limit, in which string backreaction must be taken into account. When backreaction is properly accounted for, collapsing heavy, physical, rotating strings do not generate naked singularities but only BTZ black holes, including extremal ones. The rotating string must contain world-sheet excitations in order to have consistent equations of motion; we describe such additional degrees of freedom implicitly in terms of an effective equation of state.

The partner mode with respect to a vacuum state for a given mode (like that corresponding to one of the thermal particles emitted by a black hole) is defined and calculated. The partner modes are explicitly calculated for a number of cases, in particular for the modes corresponding to a particle detector being excited by turn-on/turn-off transients, or with the thermal particles emitted by the accelerated mirror model for black hole evaporation. One of the key results is that the partner mode in general is just a vacuum fluctuation, and one can have the partner mode be located in a region where the state cannot be distinguished from the vacuum state by any series of local measurements, including the energy density. For example, “information” (the correlations with the thermal emissions) need not be associated with any energy transport. The idea that black holes emit huge amounts of energy in their last stages because of all the information which must be emitted under the assumption of black hole unitarity is found to not necessarily be the case.

We construct a ultraviolet completion of the bosonic sector of 11-dimensional supergravity motivated by string field theory. We start from a general class of theories characterized by an entire nonpolynomial form factor that allows one to avoid new poles in the propagator and improves the high-energy behavior of the loops amplitudes. Comparing these models with effective string field theory, a unique form factor is selected out. In view of this, we modify ten-dimensional supergravity and finally get a ultraviolet completion of 11-dimensional supergravity by an oxidation process. The result is a candidate for a finite and unitary particle-field limit of M-theory.

We present a nonparametric approach to reconstruct the interaction between dark energy and dark matter directly from SNIa Union 2.1 data using Gaussian processes, which is a fully Bayesian approach for smoothing data. In this method, once the equation of state ($w$) of dark energy is specified, the interaction can be reconstructed as a function of redshift. For the decaying vacuum energy case with $w=-1$, the reconstructed interaction is consistent with the standard $\mathrm{\Lambda }\mathrm{CDM}$ model, namely, there is no evidence for the interaction. This also holds for the constant $w$ cases from $-0.9$ to $-1.1$ and for the Chevallier-Polarski-Linder (CPL) parametrization case. If the equation of state deviates obviously from $-1$, the reconstructed interaction exists at 95% confidence level. This shows the degeneracy between the interaction and the equation of state of dark energy when they get constraints from the observational data.

Imposing that the excursion distance of the inflaton in field space during inflation be less than the Planck scale, we derive an upper bound on the tensor-to-scalar ratio at the cosmic microwave background scales, i.e., $r_{*,\max }$, in the general canonical single-field slow-roll inflation model, in particular, the model with non-negligible running of the spectral index ${\alpha }_s$ and/or the running of running ${\beta }_s$. We find that $r_{*,\max }\simeq 7\times {10}^{-4}$ for $n_s=0.9645$ without running and running of running, and $r_{*,\max }$ is significantly relaxed to the order of $\mathcal{O}({10}^{-2}\sim {10}^{-1})$ in the inflation model with ${\alpha }_s$ and/or ${\beta }_s\sim +\mathcal{O}({10}^{-2})$ which are marginally preferred by the Planck 2015 data.

Many inflation models predict that primordial density perturbations have a nonzero three-point correlation function, or bispectrum in Fourier space. Of the several possibilities for this bispectrum, the most common is the local-model bispectrum, which can be described as a spatial modulation of the small-scale (large-wavenumber) power spectrum by long-wavelength density fluctuations. While the local model predicts this spatial modulation to be scale independent, many variants have some scale dependence. Here we note that this scale dependence can be probed with measurements of frequency-spectrum distortions in the cosmic microwave background (CMB), in particular, highlighting Compton-$y$ distortions. Dissipation of primordial perturbations with wavenumbers $50{\mathrm{Mpc}}^{-1}\lesssim k\lesssim {10}^4{\mathrm{Mpc}}^{-1}$ gives rise to chemical-potential ($\mu$) distortions, while dissipation of those with wavenumbers $1{\mathrm{Mpc}}^{-1}\lesssim k\lesssim 50{\mathrm{Mpc}}^{-1}$ gives rise to Compton-$y$ distortions. With local-model non-Gaussianity, the distortions induced by this dissipation can be distinguished from those due to other sources via their cross correlation with the CMB temperature $T$. We show that the relative strengths of the $\mu T$ and $yT$ correlations thus probe the scale dependence of non-Gaussianity and estimate the magnitude of possible signals relative to the sensitivities of future experiments. We discuss the complementarity of these measurements with other probes of squeezed-limit non-Gaussianity.

We show that the right-handed (RH) sneutrino in the next-to-minimal supersymmetric standard model can account for the observed excess in the Fermi-LAT spectrum of gamma rays from the Galactic center, while fulfilling all the current experimental constraints from the LHC as well as from direct and indirect dark matter searches. We have explored the parameter space of this scenario, computed the gamma-ray spectrum for each phenomenologically viable solution and then performed a ${\chi }^2$ fit to the excess. Unlike previous studies based on model-independent interpretations, we have taken into account the full annihilation spectrum, without assuming pure annihilation channels. Furthermore, we have incorporated limits from direct detection experiments, LHC bounds and also the constraints from Fermi-LAT on dwarf spheroidal galaxies and gamma-ray spectral lines. In addition, we have estimated the effect of the most recent Fermi-LAT reprocessed data (pass 8). In general, we obtain good fits to the Galactic center excess (GCE) when the RH sneutrino annihilates mainly into pairs of light singletlike scalar or pseudoscalar Higgs bosons that subsequently decay in flight, producing four-body final states and spectral features that improve the goodness of the fit at large energies. The best fit (${\chi }^2=20.8$) corresponds to a RH sneutrino with a mass of 64 GeV which annihilates preferentially into a pair of light singletlike pseudoscalar Higgs bosons (with masses of order 60 GeV). Besides, we have analyzed other channels that also provide good fits to the excess. Finally, we discuss the implications for direct and indirect detection searches paying special attention to the possible appearance of gamma-ray spectral features in near future Fermi-LAT analyses, as well as deviations from the Standard Model–like Higgs properties at the LHC. Remarkably, many of the scenarios that fit the GCE can also be probed by these other complementary techniques.

In the present paper we prove a uniqueness theorem for the static and asymptotically flat solutions to the Einstein-scalar field equations which possess a photon sphere. We show that such solutions are uniquely specified by their mass $M$ and scalar charge $q$ and that they are isometric to the Janis-Newman-Winicour solution with the same mass and scalar charge subject to the inequality $\frac{q^2}{M^2}<3$.

A class of inflation theories called $\alpha$-attractors has been investigated recently with interesting properties interpolating between quadratic potentials, the Starobinsky model, and an attractor limit. Here we examine their use for late-time cosmic acceleration. We generalize the class and demonstrate how it can interpolate between thawing and freezing dark energy, and reduce the fine-tuning of initial conditions, allowing $w\approx -1$ for a prolonged period or as a de Sitter attractor.

Dark matter in the Milky Way may annihilate directly into $\gamma$ rays, producing a monoenergetic spectral line. Therefore, detecting such a signature would be strong evidence for dark matter annihilation or decay. We search for spectral lines in the Fermi Large Area Telescope observations of the Milky Way halo in the energy range 200 MeV–500 GeV using analysis methods from our most recent line searches. The main improvements relative to previous works are our use of 5.8 years of data reprocessed with the Pass 8 event-level analysis and the additional data resulting from the modified observing strategy designed to increase exposure of the Galactic center region. We search in five sky regions selected to optimize sensitivity to different theoretically motivated dark matter scenarios and find no significant detections. In addition to presenting the results from our search for lines, we also investigate the previously reported tentative detection of a line at 133 GeV using the new Pass 8 data.

It is postulated that quantum gravity is a sum over causal structures coupled to matter via scale evolution. Quantized causal structures can be described by studying simple matrix models where matrices are replaced by an algebra of quantum mechanical observables. In particular, previous studies constructed quantum gravity models by quantizing the moduli of Laplace, weight, and defining-function operators on Fefferman–Graham ambient spaces. The algebra of these operators underlies conformal geometries. We extend those results to include fermions by taking an $\mathfrak{o}\mathfrak{s}\mathfrak{p}(1|2)$ “Dirac square root” of these algebras. The theory is a simple, Grassmann, two-matrix model. Its quantum action is a Chern–Simons theory whose differential is a first-quantized, quantum mechanical Becchi-Rouet-Stora-Tyutin operator. The theory is a basic ingredient for building fundamental theories of physical observables.