This paper presents high-precision theoretical predictions for s-channel $e^{+}{e}^{-}\to l^{-}{l}^{+}$ scattering. The calculations are performed using the sanc system. They take into account complete one-loop electroweak radiative corrections as well as the longitudinal polarization of the initial beams. The reaction observables are obtained using the helicity amplitude method with taking into account the initial- and final-state fermion masses. Numerical results are given for the center-of-mass energy range $\sqrt{s}=250–1000\mathrm{GeV}$ with various degrees of polarization.

The cross sections of the process $e^{+}{e}^{-}\to \eta J/\psi$ at center-of-mass energies ($\sqrt{s}$) between 3.81 and 4.60 GeV are measured with high precision by using data samples collected with the BESIII detector operating at the BEPCII storage ring. Three structures are observed by analyzing the line shape of the measured cross sections, and a maximum-likelihood fit including three resonances is performed by assuming the lowest lying structure is the $\psi (4040)$. For the other resonances, we obtain masses of $(4218.6\pm 3.8\pm 2.5)$ and $(4382.0\pm 13.3\pm 1.7)\mathrm{MeV}/c^2$ with corresponding widths of $(82.0\pm 5.7\pm 0.4)$ and $(135.8\pm 60.8\pm 22.5)\mathrm{MeV}$, respectively, where the first uncertainties are statistical and the second ones systematic. The measured resonant parameters are consistent with those of the $Y(4220)$ and $Y(4390)$ from previous measurements of different final states. For the first time, we observe the decays of the $Y(4220)$ and $Y(4390)$ into $\eta J/\psi$ final states.

The eikonal approximation is an ideal tool to extract classical observables in gauge theory and gravity directly from scattering amplitudes. Here we consider effective theories of gravity where in addition to the Einstein-Hilbert term we include nonminimal couplings of the type $R^3$, $R^4$ and FFR. In particular, we study the scattering of gravitons and photons of frequency $\omega$ off heavy scalars of mass $m$ in the limit $m\gg \omega \gg |\overrightarrow{q}|$, where $\overrightarrow{q}$ is the momentum transfer. The presence of nonminimal couplings induces helicity-flip processes which survive the eikonal limit, thereby promoting the eikonal phase to an eikonal phase matrix. We obtain the latter from the relevant two-to-two helicity amplitudes that we compute up to one-loop order, and confirm that the leading-order terms in $\omega$ exponentiate à la Amati, Ciafaloni and Veneziano. From the eigenvalues of the eikonal phase matrix we then extract two physical observables, to 2PM order: the classical deflection angle and Shapiro time delay/advance. Whenever the classical expectation of helicity conservation of the massless scattered particle is violated, i.e., the eigenvalues of the eikonal matrix are nondegenerate, causality violation due to time advance is a generic possibility for small impact parameter. We show that for graviton scattering in the $R^4$ and FFR theories, time advance is circumvented if the couplings of these interactions satisfy certain positivity conditions, while it is unavoidable for graviton scattering in the $R^3$ theory and photon scattering in the FFR theory. The scattering processes we consider mimic the deflection of photons and gravitons off spinless heavy objects such as black holes.

We establish covariant semiclassical transport equations of massive spin-$1/2$ particles which are generated by the quantum kinetic equation modified by enthalpy current dependent terms. The purpose of modification is to take into account the noninertial properties due to the angular velocity of rotating frame which is equivalent to the fluid vorticity in the hydrodynamical approach. We present the equations satisfied by the Wigner function components and by studying their solutions in the semiclassical approximation we accomplish the transport equations.To acquire a three-dimensional kinetic theory, the relativistic kinetic equations in the comoving frame are integrated over the zeroth component of four-momentum. The resulting vector and axial-vector currents are calculated at zero temperature. There exists another three-dimensional formulation of Dirac particles which correctly addresses the noninertial features of rotating coordinates. We review it briefly and obtain the mass corrections to the chiral vector and axial-vector currents produced by this formulation.

We investigate here the local versus global visibility of a spacetime singularity formed due to the gravitational collapse of a spherically symmetric dust cloud having a nonzero velocity function. The conditions are investigated that ensure the global visibility of the singularity, in the sense that the outgoing null geodesics leave the boundary of the matter cloud in the future, whereas, in the past, these terminate at the singularity. Explicit examples of this effect are constructed. We require that this must be a strong curvature singularity in the sense of Tipler, to ensure the physical significance of the scenario considered. This may act as a counterexample to the weak cosmic censorship hypothesis.

In this paper we show how the string landscape can be constrained using observational data. We illustrate this idea by focusing on fiber inflation which is a promising class of string inflationary models in type IIB flux compactifications. We determine the values of the microscopic flux-dependent parameters which yield the best fit to the most recent cosmological datasets.

The extension of the Standard Model by assuming $U(1{)}_{\mathrm{B}\text{−}\mathrm{L}}$ gauge symmetry is very well motivated since it naturally explains the presence of heavy right-handed neutrinos required to account for the small active neutrino masses via the seesaw mechanism and thermal leptogenesis. Traditionally, we introduce three right-handed neutrinos to cancel the $[U(1{)}_{\mathrm{B}\text{−}\mathrm{L}}{]}^3$ anomaly. However, it suffices to introduce two heavy right-handed neutrinos for these purposes and therefore we can replace one right-handed neutrino by new chiral fermions to cancel the $U(1{)}_{\mathrm{B}\text{−}\mathrm{L}}$ gauge anomaly. Then, one of the chiral fermions can naturally play a role of a dark matter candidate. In this paper, we demonstrate how this framework produces a dark matter candidate which can address the so-called “core-cusp problem”. As one of the small-scale problems that the $\mathrm{\Lambda }$ cold dark matter paradigm encounters, it may imply an important clue for the nature of dark matter. One of resolutions among many is hypothesizing that sub-keV fermion dark matter halos in dwarf spheroidal galaxies are in a (quasi) degenerate configuration. We show how the degenerate sub-keV fermion dark matter candidate can be nonthermally originated in our model and thus can be consistent with the Lyman-$\alpha$ forest observation. Thereby, the small neutrino mass, baryon asymmetry, and the sub-keV dark matter become consequences of the broken B-L gauge symmetry.

We study the pion-photon transition form factor (TFF) $F^{\gamma *\gamma {\pi }^0}(Q^2)$ using a state-of-the art implementation of light cone sum rules (LCSRs) within fixed-order QCD perturbation theory. The spectral density in the dispersion relation includes all currently known radiative corrections up to the next-to-next-to-leading-order (NNLO) and all twist contributions up to order six. Predictions for the TFF are obtained for various pion distribution amplitudes (DAs) of twist two, including two-loop evolution which accounts for heavy-quark mass thresholds. The influence of the main theoretical uncertainties is quantified in order to enable a more realistic comparison with the data. The characteristics of various pion DAs are analyzed in terms of the conformal coefficients $a_2$ and $a_4$ in comparison with the $1\sigma$ and $2\sigma$ error regions of the data and the most recent lattice constraints on $a_2$ with NLO and NNLO accuracy. Our results provide more stringent bounds on the variation of the pion DA and illuminate the corresponding asymptotic behavior of the calculated TFF.

The renormalization properties of two local composite operators, $(O,V_{\mu })$, which are invariant under the infinitesimal Becchi-Rouet-Stora-Tyutin (BRST) transformations, corresponding respectively to the gauge invariant respectively to the gauge invariant description of the Higgs particle and of the massive gauge vector boson, are scrutinized in the $U(1)$ Higgs model by means of the algebraic renormalization setup. Their renormalization $Z$’s factors are explicitly evaluated at one-loop order in the $\overline{\mathrm{MS}}$ scheme by taking into due account the mixing with other gauge invariant operators. In particular, it turns out that the operator $V_{\mu }$ mixes with the gauge invariant quantity ${\partial }_{\nu }{F}_{\mu \nu }$, which has the same quantum numbers, giving rise to a $2\times 2$ mixing matrix. Moreover, two additional powerful Ward identities exist which enable us to determine the whole set of $Z$’s factors entering the $2\times 2$ mixing matrix as well as the $Z$ factor of the operator $O$ in a purely algebraic way. An explicit check of these Ward identities is provided. The final setup obtained allows for computing perturbatively the full renormalized result for any $n$-point correlation function of the scalar and vector composite operators.

We develop a quantum effective action for scalar-tensor theories of gravity which is both spacetime-diffeomorphism invariant and field reparametrization (frame) invariant beyond the classical approximation. We achieve this by extending the Vilkovisky-DeWitt formalism, treating both the scalar fields and the components of the gravitational tensor field as coordinates describing a manifold. By using tensors covariant under diffeomorphisms of this manifold, we show that scalar-tensor theories can be written in a form that is manifestly frame invariant at both classical and quantum levels. In the same context, we show that in order to maintain manifest frame invariance, we must modify the Feynman rules of theories with a nontrivial field space. We show that one such theory is general relativity by demonstrating explicitly that it has a nonzero field-space Riemann tensor. Thus, when constructing theories of quantum gravity, we must deal not only with curved spacetime, but also with a curved field space. Finally, we address the cosmological frame problem by tracing its origin to the existence of a new model function that appears in the path-integral measure. Once this function is fixed, we find that frame transformations have no effect on the quantization of the theory. The uniqueness of our improved quantum effective action is discussed.

The advent of gravitational wave (GW) astronomy has provided us with observations of black holes more massive than those known from x-ray astronomy. However, the observation of an intermediate-mass black hole (IMBH) remains a big challenge. After their second observing run, the LIGO & Virgo Scientific collaborations (LVC) placed upper limits on the coalescence rate density of nonprecessing IMBH binaries (IMBHBs). In this Numerical Relativity Injection Analysis (NuRIA), we explore the sensitivity of two of the search pipelines used by the LVC to signals from 69 numerically simulated IMBHBs with total mass greater than $200M_{\odot }$ having generic spins, out of which 27 have a precessing orbital plane. In particular, we compare the matched-filter search PyCBC, and the coherent model-independent search technique cWB. We find that, in general, cWB is more sensitive to IMBHBs than PyCBC, with the difference in sensitivity depending on the masses and spins of the source. Consequently, we use cWB to place the first upper limits on the merger rate of generically spinning IMBH binaries using publicly available data from the first Advanced LIGO observing run.

We show that the Chern-Simons (CS) state when reduced to minisuperspace is the Fourier dual of the Hartle-Hawking (HH) and Vilenkin (V) wave functions of the Universe. This is to be expected, given that the former and latter solve the same constraint equation, written in terms of conjugate variables (loosely, the expansion factor and the Hubble parameter). A number of subtleties in the mapping, related to the contour of integration of the connection, shed light on the issue of boundary conditions in quantum cosmology. If we insist on a real Hubble parameter, then only the HH wave function can be represented by the CS state, with the Hubble parameter covering the whole real line. For the V (or tunneling) wave function, the Hubble parameter is restricted to the positive real line (which makes sense, since the state only admits outgoing waves), but the contour also covers the whole negative imaginary axis. Hence, the state is not admissible if reality conditions are imposed upon the connection. Modifications of the V state, requiring the addition of source terms to the Hamiltonian constraint, are examined and found to be more palatable. In the dual picture, the HH state predicts a uniform distribution for the Hubble parameter over the whole real line; the modified V state a uniform distribution over the positive real line.

The kinetic Sunyaev Zel’dovich (kSZ) effect, cosmic microwave background (CMB) temperature anisotropies induced by scattering of CMB photons from free electrons, forms the dominant blackbody component of the CMB on small angular scales. Future CMB experiments on the resolution/sensitivity frontier will measure the kSZ effect with high significance. Through the cross-correlation with tracers of structure, it will be possible to reconstruct the remote CMB dipole field (e.g., the CMB dipole observed at different locations in the Universe) using the technique of kSZ tomography. In this paper, we derive a quadratic estimator for the remote dipole field using the cosmic infrared background (CIB) as a tracer of structure. We forecast the ability of current and next-generation measurements of the CMB and CIB to perform kSZ tomography. The total signal to noise of the reconstruction is order unity for current datasets, and can improve by a factor of up to ${10}^3$ for idealized future datasets, based on statistical error only. The CIB-based reconstruction is highly correlated with a galaxy survey-based reconstruction of the remote dipole field, which can be exploited to improve constraints on cosmological parameters and models for the CIB and distribution of baryons.

The multimessenger astrophysics of compact objects presents a vast range of environments where neutrino flavor transformation may occur and may be important for nucleosynthesis, dynamics, and a detected neutrino signal. Development of efficient techniques for surveying flavor evolution solution spaces in these diverse environments, which augment and complement existing sophisticated computational tools, could leverage progress in this field. To this end we continue our exploration of statistical data assimilation (SDA) to identify solutions to a small-scale model of neutrino flavor transformation. SDA is a machine learning formula wherein a dynamical model is assumed to generate any measured quantities. Specifically, we use an optimization formulation of SDA wherein a cost function is extremized via the variational method. Regions of state space in which the extremization identifies the global minimum of the cost function will correspond to parameter regimes in which a model solution can exist. Our example study seeks to infer the flavor transformation histories of two monoenergetic neutrino beams coherently interacting with each other and with a matter background. We require that the solution be consistent with measured neutrino flavor fluxes at the point of detection, and with constraints placed upon the flavor content at various locations along their trajectories, such as the point of emission, and the locations of the Mikheyev-Smirnov-Wolfenstein resonances. We show how the procedure efficiently identifies solution regimes and rules out regimes where solutions are infeasible. Overall, results intimate the promise of this “variational annealing” methodology to efficiently probe an array of fundamental questions that traditional numerical simulation codes render difficult to access.

The extended excess toward the Galactic Center (GC) in gamma rays inferred from Fermi-LAT observations has been interpreted as being due to dark matter (DM) annihilation. Here, we perform new likelihood analyses of the GC and show that, when including templates for the stellar galactic and nuclear bulges, the GC shows no significant detection of a DM annihilation template, even after generous variations in the Galactic diffuse emission models and a wide range of DM halo profiles. We include Galactic diffuse emission models with combinations of three-dimensional inverse Compton maps, variations of interstellar gas maps, and a central source of electrons. For the DM profile, we include both spherical and ellipsoidal DM morphologies and a range of radial profiles from steep cusps to kiloparsec-sized cores, motivated in part by hydrodynamical simulations. Our derived upper limits on the dark matter annihilation flux place strong constraints on DM properties. In the case of the pure $b$-quark annihilation channel, our limits on the annihilation cross section are more stringent than those from the Milky Way dwarfs up to DM masses of approximately TeV and rule out the thermal relic cross section up to approximately 300 GeV. Better understanding of the DM profile, as well as the Fermi-LAT data at its highest energies, would further improve the sensitivity to DM properties.

In this work, we consider an extension to the matching procedure proposed by Brodsky and de Teramond to obtain the two-body wave functions in the light-front formalism for holographic models. We compute the light-front wave function by considering different static dilaton fields and anti–de sitter (AdS)-like geometric deformations. We also prove that this procedure holds for general AdS/QCD models in asymptotically AdS geometries.

We present simple and predictive realizations of neutrino masses in theories based on the $SU(6)$ grand unifying group. At the level of the lowest-dimension operators, this class of models predicts a skew-symmetric flavor structure for the Dirac mass term of the neutrinos. In the case that neutrinos are Dirac particles, the lowest-order prediction of this construction is then one massless neutrino and two degenerate massive neutrinos. Higher-dimensional operators suppressed by the Planck scale perturb this spectrum, allowing a good fit to the observed neutrino mass matrix. A firm prediction of this construction is an inverted neutrino mass spectrum with the lightest neutrino hierarchically lighter than the other two, so that the sum of neutrino masses lies close to the lower bound for an inverted hierarchy. In the alternate case that neutrinos are Majorana particles, the mass spectrum can be either normal or inverted. However, the lightest neutrino is once again hierarchically lighter than the other two, so that the sum of neutrino masses is predicted to lie close to the corresponding lower bound for the normal or inverted hierarchy. Near future cosmological measurements will be able to test the predictions of this scenario for the sum of neutrino masses. In the case of Majorana neutrinos that exhibit an inverted hierarchy, future neutrinoless double beta experiments can provide a complementary probe.

The discrepancy between the Standard Model theory and experimental measurement of the muon magnetic moment anomaly, $a_{\mu }=(g_{\mu }-2)/2$, is connected to precision electroweak (EW) predictions via their common dependence on hadronic vacuum polarization effects. The same data for the total $e^{+}{e}^{-}\to \text{hadrons}$ cross section, ${\sigma }_{\text{had}}(s)$, are used as input into dispersion relations to estimate the hadronic vacuum polarization contributions, $a_{\mu }^{\text{had},\mathrm{VP}}$, as well as the five-flavor hadronic contribution to the running QED coupling at the $Z$-pole, $\mathrm{\Delta }{\alpha }_{\text{had}}^{(5)}(M_Z^2)$, which enters natural relations and global EW fits. The EW fit prediction of $\mathrm{\Delta }{\alpha }_{\text{had}}^{(5)}(M_Z^2)=0.02722(41)$ agrees well with $\mathrm{\Delta }{\alpha }_{\text{had}}^{(5)}(M_Z^2)=0.02761(11)$ obtained from the dispersion relation approach, but exhibits a smaller central value suggestive of a larger discrepancy $\mathrm{\Delta }{a}_{\mu }=a_{\mu }^{\exp }-a_{\mu }^{\mathrm{SM}}$ than currently expected. Postulating that the $\mathrm{\Delta }{a}_{\mu }$ difference may be due to unforeseen missing ${\sigma }_{\text{had}}(s)$ contributions, implications for $M_W$, ${\sin }^2{\theta }_{\mathrm{eff}}^{\mathrm{lep}}$ and $M_H$ obtained from global EW fits are investigated. Shifts in ${\sigma }_{\text{had}}(s)$ needed to bridge $\mathrm{\Delta }{a}_{\mu }$ are found to be excluded above $\sqrt{s}\gtrsim 0.7\mathrm{GeV}$ at the 95% C.L. Moreover, prospects for $\mathrm{\Delta }{a}_{\mu }$ originating below that energy are deemed improbable given the required increases in the hadronic cross section. Such hypothetical changes to the hadronic data are also found to affect other related observables, such as the electron anomaly, $a_e^{\text{SM}}$, the rescaled ratio $R_{e/\mu }=(m_{\mu }/m_e{)}^2(a_e^{\text{had},\mathrm{LO}\mathrm{VP}}/a_{\mu }^{\text{had},\mathrm{LO}\mathrm{VP}})$, and the running of the weak mixing angle at low energies, although the consequences of these are currently less constraining.

We compute the gravitational-wave (GW) energy flux up to the next-to-next-to-leading (NNL) order of tidal effects in a spinless compact binary system on quasicircular orbits. Starting from an effective matter action, we obtain the stress-energy tensor of the system, which we use in a GW generation formalism based on multipolar-post-Minkowskian and post-Newtonian (PN) approximations. The tidal contributions to the multipole moments of the system are first obtained, from which we deduce the instantaneous GW energy flux to NNL order (formally 7PN order). We also include the remaining tidal contributions of GW tails to the leading (formally 6.5PN) and next-to-leading (7.5PN) orders. Combining it with our previous work on the conservative equations of motion and associated energy, we get the GW phase and frequency evolution through the flux-balance equation to the same NNL order. These results extend and complete several preceding results in the literature.