With the availability of new high-statistics and wide-angle measurements for several exclusive non-$\pi N$ meson photoproduction channels from Jefferson Lab, we examine the fundamental scaling law of 90° scattering in QCD that was originally derived in the high-energy perturbative limit. The data show scaling to be prominently visible even in the medium-energy domain of 2.5 GeV $\lesssim \sqrt{s}\lesssim 2.84\mathrm{GeV}$, where $\sqrt{s}$ is the center-of-mass energy. While constituent quark exchange suffices for pseudoscalar mesons, additional gluon exchanges from higher Fock states of the hadronic wave functions appear be needed for vector-meson production. The case of the $\varphi (1020)$, where two-gluon exchanges are known to dominate, is especially illuminating.

We propose a new radiative mechanism for neutrino mass generation based on the $\mathrm{SU}(3{)}_c\otimes \mathrm{SU}(3{)}_L\otimes \mathrm{U}(1{)}_X$ electroweak gauge group.Lepton number is a symmetry of the Yukawa sector which is spontaneously broken in the gauge sector. As a result light Majorana masses arise from neutral gauge boson exchanges at the one-loop level. In addition to the isosinglet neutrinos that may be produced at the LHC through the extended gauge boson portals, the model contains new quarks which can also lie at the TeV scale, and which can provide a plethora of accessible collider phenomena.

We present a measurement of the branching fractions and charge-parity-($CP$-)violating parameters in $B\to \omega K$ decays. The results are obtained from the final data sample containing $772\times {10}^6$ $B\overline{B}$ pairs collected at the $\mathrm{{\rm Y}}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We obtain the branching fractions $\mathcal{B}(B^0\to \omega K^0)=(4.5\pm 0.4(\text{stat})\pm 0.3(\text{syst}))\times {10}^{-6},\mathcal{B}(B^{+}\to \omega K^{+})=(6.8\pm 0.4(\text{stat})\pm 0.4(\text{syst}))\times {10}^{-6}$ which are in agreement with their respective current world averages. For the $CP$-violating parameters, we obtain ${\mathcal{A}}_{\omega K_S^0}=-0.36\pm 0.19(\text{stat})\pm 0.05(\text{syst}),{\mathcal{S}}_{\omega K_S^0}=+0.91\pm 0.32(\text{stat})\pm 0.05(\text{syst}),{\mathcal{A}}_{\omega K^{+}}=-0.03\pm 0.04(\text{stat})\pm 0.01(\text{syst}),$ where $\mathcal{A}$ and $\mathcal{S}$ represent the direct and mixing-induced $CP$ asymmetry, respectively. We find no evidence of $CP$ violation in the decay channel $B^{+}\to \omega K^{+}$; however, we obtain the first evidence of $CP$ violation in the $B^0\to \omega K_S^0$ decay channel at the level of 3.1 standard deviations.

A novel method to study the bulk thermodynamics in lattice gauge theory is proposed on the basis of the Yang-Mills gradient flow with a fictitious time $t$. The energy density $ϵ$ and the pressure $P$ of $SU(3)$ gauge theory at fixed temperature are calculated directly on ${32}^3\times (6,8,10)$ lattices from the thermal average of the well-defined energy-momentum tensor $T_{\mu \nu }^R(x)$ obtained by the gradient flow. It is demonstrated that the continuum limit can be taken in a controlled manner from the $t$ dependence of the flowed data.

This paper deals with various interrelations between strings and surfaces in three-dimensional ambient space, two-dimensional integrable models, and two-dimensional and four-dimensional decomposed SU(2) Yang-Mills theories. Initially, a spinor version of the Frenet equation is introduced in order to describe the differential geometry of static three-dimensional stringlike structures. Then its relation to the structure of the $\underset{\_}{\mathrm{su}}(2)$ Lie algebra valued Maurer-Cartan one-form is presented, while by introducing time evolution of the string a Lax pair is obtained, as an integrability condition. In addition, it is shown how the Lax pair of the integrable nonlinear Schrödinger equation becomes embedded into the Lax pair of the time extended spinor Frenet equation, and it is described how a spinor-based projection operator formalism can be used to construct the conserved quantities, in the case of the nonlinear Schrödinger equation. Then the Lax pair structure of the time extended spinor Frenet equation is related to properties of flat connections in a two-dimensional decomposed SU(2) Yang-Mills theory. In addition, the connection between the decomposed Yang-Mills and the Gauß-Codazzi equation that describes surfaces in three-dimensional ambient space is presented. In that context the relation between isothermic surfaces and integrable models is discussed. Finally, the utility of the Cartan approach to differential geometry is considered. In particular, the similarities between the Cartan formalism and the structure of both two-dimensional and four-dimensional decomposed SU(2) Yang-Mills theories are discussed, while the description of two-dimensional integrable models as embedded structures in the four-dimensional decomposed SU(2) Yang-Mills theory are presented.

We compute the full one loop correction to the quartic vertex of QCD at the fully symmetric point. This allows us to define a new momentum subtraction (MOM) scheme in the class of schemes introduced by Celmaster and Gonsalves. Hence using properties of the renormalization group equation, the two loop renormalization group functions for this scheme are given.

We study Nambu-Goldstone (NG) modes or gapless modes propagating along a Skyrmion (lump) line in a relativistic and nonrelativistic $O(3)$ sigma model, the latter of which describes isotropic Heisenberg ferromagnets. We show for the nonrelativistic case that there appear two coupled gapless modes with a quadratic dispersion. In addition to the well-known Kelvin mode consisting of two translational zero modes transverse to the Skyrmion line, we show that the other consists of a magnon and dilaton, that is, a NG mode for a spontaneously broken internal $U(1)$ symmetry and a quasi-NG mode for a spontaneously broken scale symmetry of the equation of motion. We find that the commutation relations of Noether charges admit a central extension between the dilatation and phase rotation, in addition to the one between two translations found recently. The counting rule is consistent with the Nielsen-Chadha and Watanabe-Brauner relations only when we take into account quasi-NG modes.

We investigate the intrinsic uncertainty in the accuracy to which a static spacetime can be measured from scattering experiments. In particular, we focus on the Schwarzschild black hole and a spatially kinked metric that has some mathematical resemblance to an expanding universe. Under selected conditions we find that the scattering problem can be framed in terms of a lossy bosonic channel, which allows us to identify shot-noise scaling as the ultimate scaling limit to the estimation of the spacetimes. Fock state probes with particle counting measurements attain this ultimate scaling limit and the scaling constants for each spacetime are computed and compared to the practical strategies of coherent state probes with heterodyne and homodyne measurements. A promising avenue to analyze the quantum limit of the analogue spacetimes in optical waveguides is suggested.

The conformal field equations are used to discuss the local existence of spherically symmetric solutions to the Einstein-Yang-Mills system which behave asymptotically like the anti–de Sitter spacetime. By using a gauge based on conformally privileged curves we obtain a formulation of the problem in terms of an initial boundary value problem on which a general class of maximally dissipative boundary conditions can be discussed. The relation between these boundary conditions and the notion of mass on asymptotically anti–de Sitter spacetimes is analyzed.

Gravitational wave burst is a catch-all category for signals whose durations are shorter than the observation period. We apply a method new to gravitational wave data analysis—Bayesian nonparametrics—to the problem of gravitational wave detection, with an emphasis on pulsar timing array observations. In Bayesian nonparametrics, constraints are set on the function space that may be reasonably thought to characterize the range of gravitational wave signals. This differs from the approaches currently employed or proposed, which focus on introducing parametric signal models or looking for excess power as evidence of the presence of a gravitational wave signal. Our Bayesian nonparametrics analysis method addresses two issues: (i) investigate if a gravitational wave burst is present in the data; (ii) infer the sky location of the source and the duration of the burst. Compared with the popular method proposed by Finn and Lommen, our method improves in two aspects: (i) we can estimate the burst duration by adding the prior that the gravitational wave signals are smooth, while Finn and Lommen ignored this important point; (ii) we perform a full Bayesian analysis by marginalizing over all possible parameters and provide robust inference on the presence of gravitational waves, while Finn and Lommen chose to optimize over parameters, which would increase the false alarm risk and also underestimate the parameter uncertainties.

We continue the study of mild transient reductions in the speed of sound of the adiabatic mode during inflation, of their effect on the primordial power spectrum and bispectrum, and of their detectability in the cosmic microwave background (CMB). We focus on the regime of moderately sharp mild reductions in the speed of sound during uninterrupted slow-roll inflation, a theoretically well motivated and self-consistent regime that admits an effective single-field description. The signatures on the power spectrum and bispectrum were previously computed using a slow-roll Fourier transform (SRFT) approximation, and here we compare it with generalized slow roll and in-in methods, for which we derive new formulas that account for moderately sharp features. The agreement between them is excellent, and also with the power spectrum obtained from the numerical solution to the equation of motion. We show that, in this regime, the SRFT approximation correctly captures with simplicity the effect of higher derivatives of the speed of sound in the mode equation, and makes manifest the correlations between power spectrum and bispectrum features. In a previous paper we reported hints of these correlations in the Planck data and here we perform several consistency checks and further analyses of the best fits, such as polarization and local significance at different angular scales. For the data analysis, we show the excellent agreement between the CLASS and CAMB Boltzmann codes. Our results confirm that the theoretical framework is consistent, and they suggest that the predicted correlations are robust enough to be searched for in CMB and large scale structure surveys.

Modified theories of electrodynamics that include violations of Lorentz symmetry often allow for the possibility of vacuum Cerenkov radiation. This phenomenon has previously been studied in a number of Lorentz-violating theories, but none of the methods that have previously been developed are sufficient to study a theory with a timelike Chern-Simons term $k_{AF}$, because such a term may generate exponentially growing solutions to the field equations. Searching for vacuum Cerenkov radiation in a theory with a purely timelike Chern-Simons term using only elementary methods, we find that, despite the presence of the runaway modes, a charge in uniform nonrelativistic motion does not radiate energy, up to second order in the velocity.

We study here the interaction of $D{\overline{D}}^{*}$ in the isospin $I=1$ channel in light of recent theoretical advances that allow us to combine elements of the local hidden gauge approach with heavy quark spin symmetry. We find that the exchange of light $q\overline{q}$ is Okubo-Zweig-Iizuka (OZI) suppressed and thus we concentrate on the exchange of heavy vectors and of two pion exchange. The latter is found to be small compared to the exchange of heavy vectors, which then determines the strength of the interaction. A barely $D{\overline{D}}^{*}$ bound state decaying into ${\eta }_c\rho$ and $\pi J/\psi$ is found. At the same time we reanalyze the data of the BESIII experiment on $e^{+}{e}^{-}\to {\pi }^{\pm }(D{\overline{D}}^{*}{)}^{\mp }$, from where a $Z_c(3885)$ state was claimed, associated to a peak in the $(D{\overline{D}}^{*}{)}^{\mp }$ invariant mass distribution close to threshold, and we find the data compatible with a resonance with mass around 3875 MeV and width around 30 MeV. We discuss the possibility that this and the $Z_c(3900)$ state found at BESIII, reconfirmed at 3894 MeV at Belle, or 3885 MeV at CLEO, could all be the same state and correspond to the one that we find theoretically.

Uncertainties in the simulation of Higgs boson production with up to two jets at next-to-leading-order accuracy are investigated. Traditional uncertainty estimates based on scale variations are extended employing different functional forms for the central scale, and the impact of details in the implementation of the parton shower is discussed.

A rainbow-ladder truncation of QCD’s Dyson-Schwinger equations is used to calculate $\rho$- and $\varphi$-meson valence-quark (twist-two parton) distribution amplitudes (PDAs) via a light-front projection of their Bethe-Salpeter wave functions, which possess $S$- and $D$-wave components of comparable size in the meson rest frame. All computed PDAs are broad concave functions, whose dilation with respect to the asymptotic distribution is an expression of dynamical chiral symmetry breaking. The PDAs can be used to define an ordering of valence-quark light-front spatial extent within mesons: this size is smallest within the pion and increases through the $\perp$ polarization to the $\parallel$ polarization of the vector mesons; effects associated with the breaking of SU(3)-flavor symmetry are significantly smaller than those associated with altering the polarization of vector mesons. Notably, the predicted pointwise behavior of the $\rho$-meson PDAs is in quantitative agreement with that inferred recently via an analysis of diffractive vector-meson photoproduction experiments.

Neutrino-neutrino refraction can lead to nonperiodic flavor oscillations in dense neutrino gases, and it has been hypothesized that some solutions are chaotic in nature. This is of particular interest in the case of neutrino emission from core-collapse supernovae where the measurement of the spectral shape for different flavors can provide crucial information about both neutrino physics and the physical conditions close to the proto-neutron star. Whether a system is chaotic or not can be assessed by the Lyapunov exponents, which quantify the rate of divergence of nearby trajectories in the system. We have done a numerical case study for a simple toy model of two neutrino flavors with two momentum states traveling against each other, which is known to exhibit flavor transition instabilities. We find the leading Lyapunov exponent to be positive in all cases, confirming the chaoticity of the system for both the normal and the inverted neutrino mass hierarchy. However, more Lyapunov exponents were approximately zero in the inverted hierarchy compared to the normal, which has implications for the stability of the system. To investigate this, we have calculated a generalized set of normal modes, the so-called covariant Lyapunov vectors. The covariant Lyapunov vectors associated with vanishing Lyapunov exponents showed the existence of marginally stable directions in phase space for some cases. While our analysis was done for a toy model example, it should work equally well for more realistic cases of neutrinos streaming from a proto-neutron star and provide valuable insight into the nature of the flavor instability. We finally stress that our approach captures many more properties of the physical system than the linear stability analyses which have previously been performed.

We consider the two most general families of the $(1+1)\mathrm{D}$ Dirac systems with transparent scalar potentials and two related families of the paired reflectionless Schrödinger operators. The ordinary $\mathcal{N}=2$ supersymmetry for such Schrödinger pairs is enlarged up to an exotic $\mathcal{N}=4$ nonlinear centrally extended supersymmetric structure, which involves two bosonic integrals composed from the Lax-Novikov operators for the stationary Korteweg–de Vries hierarchy. Each associated single Dirac system displays a proper $\mathcal{N}=2$ nonlinear supersymmetry with a nonstandard grading operator. One of the two families of the first- and second-order systems exhibits the unbroken supersymmetry, while another is described by the broken exotic supersymmetry. The two families are shown to be mutually transmuted by applying a certain limit procedure to the soliton scattering data. We relate the topologically trivial and nontrivial transparent potentials with self-consistent inhomogeneous condensates in the Bogoliubov–de Gennes and Gross-Neveu models and indicate the exotic $\mathcal{N}=4$ nonlinear supersymmetry of the paired reflectionless Dirac systems.

In this work, we investigate the consequences of the spontaneous breaking of Lorentz symmetry, triggered by the bumblebee vector field, on the usual Einstein-Hilbert theory. Specifically, we consider the Einstein-Hilbert action modified by the bumblebee dynamic field, and evaluate the graviton propagator using an extended basis of Barnes-Rivers tensor projectors, involving the Lorentz-violating vector. Once the propagator is carried out, we proceed with discussing the consistency of the model, writing the dispersion relations, and analyzing causality and unitarity. We verify that this model possesses two dispersion relations: one provides causal and unitary propagating modes, while the second one yields a causal but nonunitary mode which spoils the physical consistency of the model.