We report results on studies of the $e^{+}{e}^{-}$ annihilation into three-body $\mathrm{\Upsilon }(nS){\pi }^{+}{\pi }^{-}$ ($n=1,2,3$) final states including measurements of cross sections and the full amplitude analysis. The cross sections measured at $\sqrt{s}=10.866\mathrm{GeV}$ and corrected for the initial state radiation are $\sigma (e^{+}{e}^{-}\to \mathrm{\Upsilon }(1S){\pi }^{+}{\pi }^{-})=(2.27\pm 0.12\pm 0.14)\mathrm{pb}$, $\sigma (e^{+}{e}^{-}\to \mathrm{\Upsilon }(2S){\pi }^{+}{\pi }^{-})=(4.07\pm 0.16\pm 0.45)\mathrm{pb}$, and $\sigma (e^{+}{e}^{-}\to \mathrm{\Upsilon }(3S){\pi }^{+}{\pi }^{-})=(1.46\pm 0.09\pm 0.16)\mathrm{pb}$. Amplitude analysis of the three-body $\mathrm{\Upsilon }(nS){\pi }^{+}{\pi }^{-}$ final states strongly favors $I^G(J^P)=1^{+}(1^{+})$ quantum-number assignments for the two bottomonium-like $Z_b^{\pm }$ states, recently observed in the $\mathrm{\Upsilon }(nS){\pi }^{\pm }$ and $h_b(mP){\pi }^{\pm }$ ($m=1,2$) decay channels. The results are obtained with a $121.4{\mathrm{fb}}^{-1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider.

We present a measurement of the distribution of the variable ${\varphi }_{\eta }^{*}$ for muon pairs with masses between 30 and 500 GeV, using the complete run II data set collected by the D0 detector at the Fermilab Tevatron proton-antiproton collider. This corresponds to an integrated luminosity of $10.4{\mathrm{fb}}^{-1}$ at $\sqrt{s}=1.96\mathrm{TeV}$. The data are corrected for detector effects and presented in bins of dimuon rapidity and mass. The variable ${\varphi }_{\eta }^{*}$ probes the same physical effects as the $Z/{\gamma }^{*}$ boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. These are the first measurements at any collider of the ${\varphi }_{\eta }^{*}$ distributions for dilepton masses away from the $Z\to {\ell }^{+}{\ell }^{-}$ boson mass peak. The data are compared to QCD predictions based on the resummation of multiple soft gluons.

We investigate the nucleon tensor charge from current experiments by a combined analysis of the Collins asymmetries in two hadron production in $e^{+}{e}^{-}$ annihilations and semi-inclusive hadron production in deep inelastic scattering processes. The transverse momentum dependent evolution is taken into account, for the first time, in the global fit of the Collins fragmentation functions and the quark transversity distributions at the approximate next-to-leading logarithmic order. We obtain the nucleon tensor charge contribution from up and down quarks as $\delta u=+0.30_{-0.08}^{+0.12}$ and $\delta d=-0.20_{-0.11}^{+0.28}$ at 90% confidence level for momentum fraction $0.0065\le x_B\le 0.35$ and $Q^2=10{\mathrm{GeV}}^2$.

We find dispersion laws for the photon propagating in the presence of mutually orthogonal constant external electric and magnetic fields in the context of the $\theta$-expanded noncommutative QED. We show that there is no birefringence to the first order in the noncommutativity parameter $\theta$. By analyzing the group velocities of the photon eigenmodes we show that there occurs superluminal propagation for any direction. This phenomenon depends on the mutual orientation of the external electromagnetic fields and the noncommutativity vector. We argue that the propagation of signals with superluminal group velocity violates causality in spite of the fact that the noncommutative theory is not Lorentz invariant and speculate about possible workarounds.

Using holography, we study the low-lying mesonic spectrum of a range of asymptotically free gauge theories. First, we revisit a simple top-down holographic model of QCD-like dynamics with predictions in the $M_{\rho }$-$M_{\pi }$ plane. The meson masses in this model are in very good agreement with lattice gauge theory calculations in the quenched approximation. We show that the key ingredient for the meson mass predictions is the running of the anomalous dimension of the quark condensate $\gamma$. This provides an explanation for the agreement of holographic and quenched lattice gauge theory calculations. We then study the “dynamic AdS/QCD model,” in which the gauge theory dynamics is included by a choice for the running of $\gamma$. We use the naive two-loop perturbative running of the gauge coupling extrapolated to the nonperturbative regime to estimate the running of $\gamma$ across a number of theories. We consider models with quarks in the fundamental, adjoint, two-index symmetric and two-index antisymmetric representations. We display predictions for $M_{\rho }$, $M_{\pi }$, $M_{\sigma }$ and the lightest glueball mass. Many of these theories, where the contribution to the running of $\gamma$ is dominated by the gluons, give very similar spectra, which also match with lattice expectations for QCD. On the other hand, a significant difference between spectra in different holographic models is seen for theories where the quark content changes the gradient of the running of $\gamma$ around the scale at which chiral symmetry breaking is triggered at $\gamma \simeq 1$. For these walking theories, we see an enhancement of the $\rho$ mass and a suppression of the $\sigma$ mass. Both phenomena are characteristic for walking behavior in the physical meson masses.

A homogeneous and isotropic cosmological model with a positive cosmological constant is considered. The matter sector is given by a massless scalar field, which can be used as an internal time to deparametrize the theory. The idea is to study and compare the evolutions of a quantum and a classical probability distribution by performing a decomposition of both distributions in their corresponding moments. For the numerical analysis an initial peaked Gaussian state in the volume will be chosen. Furthermore, in order to check the robustness of certain results, as initial state both a slightly deformed Gaussian, as well as another completely different state, will also be studied. Differences and similarities between classical and quantum moments are pointed out. In particular, for a subset of moments classical and quantum evolutions are quite similar, but certain variables show remarkable differences.

Recently it was shown that Dirac’s method of quantizing constrained dynamical systems can be used to impose the Lorenz gauge condition in a four-dimensional cosmological spacetime. In this paper we use Dirac’s method to impose the Lorenz gauge condition in a general four-dimensional conformally flat spacetime and find that there is no particle production. We show that in cosmological spacetimes with dimension $D\ne 4$ there will be particle production when the scale factor changes, and we calculate the particle production due to a sudden change.

We derive the null energy condition, understood as a constraint on the Einstein-frame Ricci tensor, from world sheet string theory. For a closed bosonic string propagating in a curved geometry, the spacetime interpretation of the Virasoro constraint condition is precisely the null energy condition, to leading nontrivial order in the ${\alpha }^{\prime }$ expansion. Thus the deepest origin of the null energy condition lies in world sheet diffeomorphism invariance.

A number of groups have employed radio observations of the Galactic center to derive stringent constraints on the annihilation cross section of weakly interacting dark matter. In this paper, we show that electron energy losses in this region are likely to be dominated by inverse Compton scattering on the interstellar radiation field, rather than by synchrotron, considerably relaxing the constraints on the dark matter annihilation cross section compared to previous works. Strong convective winds, which are well motivated by recent observations, may also significantly weaken synchrotron constraints. After taking these factors into account, we find that radio constraints on annihilating dark matter are orders of magnitude less stringent than previously reported, and are generally weaker than those derived from current gamma-ray observations.

We consider spherically symmetric inhomogeneous pressure Stephani universes, with the center of symmetry being our location. The main feature of these models is that comoving observers do not follow geodesics. In particular, comoving perfect fluids necessarily have a radially dependent pressure. We consider a subclass of these models characterized by some inhomogeneity parameter $\beta$. We show also that the velocity of sound of comoving perfect fluids, like the (effective) equation of state parameter, acquires away from the origin a time- and radial-dependent change proportional to $\beta$. In order to produce a realistic universe accelerating at late times without a dark energy component, one must take $\beta <0$. The redshift acquires a modified dependence on the scale factor $a(t)$ with a relative modification of $-9\%$, peaking at $z\sim 4$ and vanishing at the big bang and today on our past light cone. The equation of state parameter and the speed of sound of dustlike matter (corresponding to a vanishing pressure at the center of symmetry $r=0$) behave in a similar way, and away from the center of symmetry they become negative—a property usually encountered in the dark energy component only. In order to mimic the observed late-time accelerated expansion, the matter component must significantly depart from standard dust, presumably ruling this subclass of Stephani models out as a realistic cosmology. The only way to accept these models is to keep all standard matter components of the universe, including dark energy, and take an inhomogeneity parameter $\beta$ that is sufficiently small.

By considering linear-order departures from general relativity, we compute a novel expression for the weak lensing convergence power spectrum under alternative theories of gravity. This comprises an integral over a “kernel” of general relativistic quantities multiplied by a theory-dependent “source” term. The clear separation between theory-independent and -dependent terms allows for an explicit understanding of each physical effect introduced by altering the theory of gravity. We take advantage of this to explore the degeneracies between gravitational parameters in weak lensing observations.

In the wake of exploring uncertainty in the full angular distribution of the $B\to K\pi +{\mu }^{+}{\mu }^{-}$ decay caused by the presence of the intermediate scalar $K_0^{*}$ meson, we perform the straightforward calculation of the $B(B_s)\to S$ ($S$ is a scalar meson) transition form factors in the full kinematical region within the covariant quark model. We restrict ourselves to the scalar mesons below 1 GeV: $a_0(980)$, $f_0(500)$, $f_0(980)$, and $K_0^{*}(800)$. As an application of the obtained results we calculate the widths of the semileptonic and rare decays $B(B_s)\to S\ell \overline{\nu }$, $B(B_s)\to S\ell \overline{\ell }$, and $B(B_s)\to S\nu \overline{\nu }$. We compare our results with those obtained in other approaches.

A symmetry-preserving Dyson-Schwinger equation treatment of a vector-vector contact interaction is used to compute dressed-quark-core contributions to the nucleon $\sigma$-term and tensor charges. The latter enable one to directly determine the effect of dressed-quark electric dipole moments (EDMs) on neutron and proton EDMs. The presence of strong scalar and axial-vector diquark correlations within ground-state baryons is a prediction of this approach. These correlations are active participants in all scattering events and thereby modify the contribution of the singly represented valence quark relative to that of the doubly represented quark. Regarding the proton $\sigma$-term and that part of the proton mass which owes to explicit chiral symmetry breaking, with a realistic $d\text{−}u$ mass splitting, the singly represented $d$ quark contributes 37% more than the doubly represented $u$ quark; and in connection with the proton’s tensor charges, ${\delta }_{T}u$, ${\delta }_{T}d$, the ratio ${\delta }_{T}d/{\delta }_{T}u$ is 18% larger than anticipated from simple quark models. Of particular note, the size of ${\delta }_{T}u$ is a sensitive measure of the strength of dynamical chiral symmetry breaking; and ${\delta }_{T}d$ measures the amount of axial-vector diquark correlation within the proton, vanishing if such correlations are absent.

Recently there has been much interest in the tauonic semileptonic meson decays $B\to D+\tau +{\nu }_{\tau }$ and $B\to D^{*}+\tau +{\nu }_{\tau }$, where one has found larger rates than what is predicted by the Standard Model. We analyze the corresponding semileptonic baryon decays ${\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^{+}+{\tau }^{-}+{\overline{\nu }}_{\tau }$ with particular emphasis on the lepton helicity flip and scalar contributions which vanish for zero lepton masses. We calculate the total rate, the differential decay distributions, the longitudinal and transverse polarization of the daughter baryon ${\mathrm{\Lambda }}_c^{+}$ and the $\tau$ lepton, and the lepton-side forward-backward asymmetries. The nonvanishing polarization of the daughter baryon ${\mathrm{\Lambda }}_c^{+}$ leads to hadron-side asymmetries in e.g. the decay ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Lambda }}^0+{\pi }^{+}$ and azimuthal correlations between the two final-state decay planes which we specify. We provide numerical results on these observables using results of the covariant confined quark model. We find large lepton mass effects in the $q^2$ spectra and in the polarization observables.

In this paper we study nuclear effects in the neutrino production of pions. We found that in a Bjorken kinematics, for moderate $x_B$ accessible in ongoing and forthcoming neutrino experiments, the cross section is dominated by the incoherent contribution; the coherent contribution becomes visible only for small $|t|\lesssim 1/R_A^2$, which requires $x_B\lesssim 0.1$. Our results could be relevant to the kinematics of the ongoing MINERvA experiment in the middle-energy regime. We provide a code which could be used for the evaluation of the neutrino induced deeply virtual meson production observables using different parametrizations of generalized parton distributions and different models of nuclear structure.

In this article the feasibility of using charge coupled devices (CCD) to detect low-energy neutrinos through their coherent scattering with nuclei is analyzed. The detection of neutrinos through this standard model process has been elusive because of the small energy deposited in such interaction. Typical particle detectors have thresholds of a few keV, and most of the energy deposition expected from coherent scattering is well below this level. The CCD detectors discussed in this paper can operate at a threshold of approximately 30 eV, making them ideal for observing this signal. On a CCD array of 500 g located next to a power nuclear reactor the number of coherent scattering events expected is about 3000 events/year. Our results shows that a detection with a confidence level of 99% can be reached within 16 days of continuous operation; with the current 52 g detector prototype this time lapse extends to five months.

Electromagnetic media with generic linear response provide a rich class of Lorentz violation models. In the framework of a general covariant metric-free approach, we study electromagnetic wave propagation in these media. We define the notion of an optic tensor and present its unique canonical irreducible decomposition into the principle and skewon parts. The skewon contribution to the Minkowski vacuum is a subject that does not arise in the ordinary models of Lorentz violation based on a modified Lagrangian. We derive the covector parametrization of the skewon optic tensor and discuss its $U(1)$-gauge symmetry. We obtain several compact expressions for the contribution of the principle and skewon optic tensor to the dispersion relation. As an application of the technique proposed here, we consider the case of a generic skewon tensor contributed to a simple metric-type principle part. Our main result: Every solution of the skewon-modified Minkowski dispersion relation is necessarily spacelike or null. It provides an extreme violation of the Lorentz symmetry. The case of the antisymmetric skewon is studied in detail, and some new special cases (electric, magnetic, and degenerate) are discovered. In the case of a skewon represented by a symmetric matrix, we observe a parametric gap that has some similarity to the Higgs model. We worked out a set of specific examples that justify the generic properties of the skewon models and demonstrate the different types of Lorentz violation phenomena.

$R+R^2$ supergravity is known to be equivalent to standard supergravity coupled to two chiral supermultiples with a no-scale Kähler potential. Within this framework, that can accommodate vanishing vacuum energy and spontaneous supersymmetry breaking, we consider modifications of the associated superpotential and study the resulting models, which, viewed as generalizations of the Starobinsky model, for a range of the superpotential parameters, describe viable single-field slow-roll inflation. In all models studied in this work, the tensor-to-scalar ratio is found to be small, well below the upper bound established by the very recent PLANCK and BICEP2 data.

We study the thermodynamical properties of black holes when described as gases of indistinguishable punctures with a chemical potential. In this picture, which arises from loop quantum gravity, the black hole microstates are defined by finite families of half-integers spins coloring the punctures, and the near-horizon energy measured by quasilocal stationary observers defines the various thermodynamical ensembles. The punctures carry excitations of quantum geometry in the form of quanta of area, and the total horizon area $a_{\mathrm{H}}$ is given by the sum of these microscopic contributions. We assume here that the system satisfies the Bose-Einstein statistics, and that each microstate is degenerate with a holographic degeneracy given by $\exp (\lambda a_{\mathrm{H}}/{\ell }_{\mathrm{Pl}}^2)$ and $\lambda >0$. We analyze in detail the thermodynamical properties resulting from these inputs, and in particular compute the grand canonical entropy. We explain why the requirements that the temperature be fixed to the Unruh temperature and that the chemical potential vanishes do not specify completely the semiclassical regime of large horizon area, and classify in turn what the various regimes can be. When the degeneracy saturates the holographic bound ($\lambda =1/4$), there exists a semiclassical regime in which the subleading corrections to the entropy are logarithmic. Furthermore, this regime corresponds to a Bose-Einstein condensation, in the sense that it is dominated by punctures carrying the minimal (or ground state) spin value $1/2$.

In this paper, we explore higher-dimensional asymptotically flat wormhole geometries in the framework of Gauss-Bonnet (GB) gravity and investigate the effects of the GB term, by considering a specific radial-dependent redshift function and by imposing a particular equation of state. This work is motivated by previous assumptions that wormhole solutions were not possible for the $k=1$ and $\alpha <0$ case, where $k$ is the sectional curvature of an $(n-2)$-dimensional maximally symmetric space, and $\alpha$ is the Gauss-Bonnet coupling constant. However, we emphasize that this discussion is purely based on a nontrivial assumption that is only valid at the wormhole throat, and cannot be extended to the entire radial-coordinate range. In this work, we provide a counterexample to this claim, and find for the first time specific solutions that satisfy the weak energy condition throughout the entire spacetime, for $k=1$ and $\alpha <0$. In addition to this, we also present other wormhole solutions which alleviate the violation of the weak energy condition in the vicinity of the wormhole throat.