Neutrino oscillation experiments require a precise measurement of the neutrino energy. However, the kinematic detection of the final-state neutron in the neutrino interaction is missing in current neutrino oscillation experiments. The missing neutron kinematic detection results in a smaller detected neutrino energy than the true neutrino energy. A novel 3D-projection scintillator tracker, which consists of roughly ten million active cubes covered with an optical reflector, is capable of measuring the neutron kinetic energy and direction on an event-by-event basis using the time-of-flight technique thanks to the fast timing, fine granularity, and high light yield. The ${\overline{\nu }}_{\mu }$ interactions tend to produce neutrons in the final state. By measuring the neutron kinetic energy, the ${\overline{\nu }}_{\mu }$ energy can be reconstructed better, allowing a tighter incoming neutrino flux constraint. This article shows the detector’s ability to reconstruct neutron kinetic energy and the ${\overline{\nu }}_{\mu }$ flux constraint achieved by selecting the charged-current interactions without mesons or protons in the final state.

Based on $7.33{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data taken at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we measure the branching fraction of $D_s^{*+}\to D_s^{+}{\pi }^0$ relative to that of $D_s^{*+}\to D_s^{+}\gamma$ to be $(6.16\pm 0.43\pm 0.18)\%$. The first uncertainty is statistical and the second one is systematic. By using the world average value of the branching fraction of $D_s^{*+}\to D_s^{+}{e}^{+}{e}^{-}$, we determine the branching fractions of $D_s^{*+}\to D_s^{+}\gamma$ and $D_s^{*+}\to D_s^{+}{\pi }^0$ to be $(93.57\pm 0.38\pm 0.22)\%$ and $(5.76\pm 0.38\pm 0.16)\%$, respectively.

The Weyl double copy relates vacuum solutions in general relativity to Abelian gauge fields in Minkowski spacetime. In a previous work, we showed how the Weyl double copy can be extended to provide a treatment of external gravitational sources consistent with the classical Kerr-Schild double copy. Using this generalization, here we provide a complete double-copy analysis of electrovacuum Petrov type-D spacetimes. This includes the first analysis of the charged C metric, whose single-copy interpretation invokes the two-potential formalism of electrodynamics. We also present the first double-copy prescription for the Ricci spinor, which for nonaccelerating spacetimes, takes a form similar to the original double-copy relation for the Weyl spinor.

The recently proposed Skordis-Złośnik theory is the first relativistic modified Newtonian dynamics (MOND) theory that can recover the success of the standard $\mathrm{\Lambda }\mathrm{CDM}$ model at matching observations of the cosmic microwave background. This paper aims to revisit the Newtonian and MOND approximations and the gravitational wave analysis of the theory. For the local gravitational parameters, we show that one could obtain both time-varying effective Newtonian gravitational constant $G_{\mathrm{N}}$ and time-varying characteristic MOND acceleration scale $a_{\mathrm{MOND}}$, by relaxing the static assumption extensively adopted in the literature. Specially, we successfully demonstrate how to reproduce the redshift dependence of $a_{\mathrm{MOND}}$ observed in the nmagneticum cold dark matter simulations. For the gravitational waves, we show that there are only two tensor polarizations and reconfirm that its speed is equal to the speed of light.

We present rapidly rotating neutron stars featuring wormholes in their centers. They arise in general relativity in the presence of a ghost scalar field. The nuclear matter is described by a polytropic equation of state, yielding realistic masses and radii for the neutron stars. The wormholes possess small circumferential radii of size up to 3 km. With increasing wormhole size, the masses and radii of the stars decrease, while the domain of existence of these rotating mixed neutron-star-plus-wormhole systems retains the characteristic properties of a rotating neutron star domain. The question of stability of the mixed configurations under consideration is briefly discussed.

The accretion of matter onto primordial black holes (PBHs) during the dark ages and the subsequent energy injection in the medium should have left imprints on the cosmic microwave background (CMB) anisotropies. Recent works have claimed stringent CMB limits on the PBH abundance, hardly compatible with a PBH interpretation of the gravitational-wave observations of binary black hole (BH) mergers. By using a more realistic accretion model based on hydrodynamical simulations and conservative assumptions for the emission efficiency, we show that CMB limits on the PBH abundance are up to 2 orders of magnitude less stringent than previously estimated between 10 and ${10}^4$ $M_{\odot }$. This reopens the possibility that PBHs might explain at the same time (at least a fraction of) the dark matter, some of the LIGO-Virgo-KAGRA binary BH mergers, and the existence of supermassive BHs. More generally, we emphasize that PBH accretion can be a rather complex physical process with velocity dependences that are hard to assess, which introduces large uncertainties in accretion-based limits on the PBH abundance.

Scalar induced gravitational waves are produced from primordial curvature perturbations in the second order of perturbations. We constrain the fractional energy density of scalar induced gravitational waves from gravitational wave observations. If there is no detection of scalar induced gravitational waves, the fractional energy density of scalar induced gravitational waves is constrained by some upper limits. Depending on these upper limits, we can obtain the constraints on the power spectrum of the primordial curvature perturbations. For a power-law scalar power spectrum, the constraints on the power spectrum are affected by adding the upper limit of scalar induced gravitational waves from the Square Kilometer Array (SKA). In the standard model, the mean values of the scalar amplitude and the spectral index shift to lower values when the SKA is added to the combination of cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) datasets, namely $\ln ({10}^{10}{A}_s)=3.038\pm 0.013$ and $n_s=0.9589_{-0.0011}^{+0.0021}$ at 68% confidence level. We also consider the effects of the existing ground-based gravitational-wave detectors, the existing pulsar timing arrays and Five-hundred-meter Aperture Spherical radio Telescope, while the constraints from $\mathrm{CMB}+\mathrm{BAO}$ datasets are totally within their upper limits of scalar induced gravitational waves. Furthermore, we characterize the scalar fluctuation spectrum in terms of the spectral index $n_s$ and its first two derivatives. We calculate corresponding power spectrum of scalar induced gravitational waves theoretically and give the constraints on the running of the spectral index and the running of the running of the spectral index.

In recent work we showed that the relic dark matter abundance of QCD axions can be altered when the Peccei-Quinn (PQ) field is coupled to very light scalar/s, rendering the effective axion mass dynamical in the early universe. In this work we develop this framework further, by introducing a new extended symmetry group to protect the new particles’ mass. We find that with a new global $SO(N)$ symmetry, with large $N$, we can not only account for the lightness of the new scalars, but we can reduce the axion relic abundance in a technically natural way. This opens up the possibility of large PQ scales, including approaching the grand unified theory (GUT) scale, and still naturally producing the correct relic abundance of axions. Also, in these models the effective PQ scale is relatively small in the very early universe, and so this can help toward alleviating the isocurvature problem from inflation. Furthermore, instead of possible overclosure from cosmic strings, the extended symmetry implies the formation of nontopological textures which provide a relatively small abundance.

In this paper, we consider the hypothesis that fractions of dark matter could be constituted by primordial black holes (PBHs). To test this possibility, we work out the observational properties of a static black hole embedded in the dark matter envelope made of a PBH source. The corresponding modifications of geometry due to such a physical system are investigated, with a particular focus on the accretion disk luminosity in spiral galaxies. The impact of the PBH presence is analyzed through modification of the disk luminosity and kinematic quantities. Thus, we discuss possible constraints on the PBH abundance in view of the most recent theoretical bounds. The results of our study indicate that suitable PBH masses are $M_{\mathrm{PBH}}\in [{10}^6,{10}^{12}]M_{\odot }$ for PBH fractions $f_{\mathrm{PBH}}\in [{10}^{-3},1]$. In particular, a comparison with the predictions of the exponential sphere density profile for dark matter suggests that the best-matching configuration is achieved for $f_{\mathrm{PBH}}=1$ and $M_{\mathrm{PBH}}={10}^6{M}_{\odot }$. Consequences with respect to the current knowledge on primordial black hole physics are discussed.

The light hadron decay processes of $Z_b(10610)/Z_b(10650)$ provide us a way to study their nature and decay mechanism. In this work, we evaluate the branching ratios of $Z_b(10610)/Z_b(10650)\to VP$ ($V$ and $P$ stand for light vector and pseudoscalar mesons, respectively) using an effective Lagrangian approach, in which the contributions of intermediate bottomed meson triangle loops are considered. In our calculations, the $Z_b(10610)$ and $Z_b(10650)$ are regarded as $B{\overline{B}}^{*}+\mathrm{c}.\mathrm{c}.$ and $B^{*}{\overline{B}}^{*}$ molecular states, respectively. The predicted branching ratios of $Z_b(10610)\to VP$ are about in the order of ${10}^{-2}$, while the branching ratios of $Z_b(10650)\to VP$ are in the order of ${10}^{-3}$. Furthermore, the dependence of these ratios between different decay modes of $Z_b(10610)/Z_b(10650)$ on the mixing $\eta -{\eta }^{\prime }$ angle ${\theta }_P$ is investigated, which may be a good quantity for the experiments. It is hoped that the calculations here could be tested by future experiments.

This work is a continuation in our series of papers that addresses quark models of hadronic structure on the light front, motivated by the QCD vacuum structure and lattice results. In this paper we focus on the importance of diquark correlations, which we describe by a quasilocal four-fermion effective ’t Hooft interaction induced by instantons. The same interaction is also shown to generate extra quark-antiquark pairs of the “sea.” Its higher order iteration can be included via “pion mediation”: both taken together yield a quantitative description of the observed flavor asymmetry of antiquarks sea. Finally we discuss the final step needed to bridge the gap between hadronic spectroscopy and parton observables, by forward DGLAP evolution toward the chiral upper scale of ∼1  GeV2.

This work is a continuation in our series of papers that addresses quark models of hadronic structure on the light front. The chief focus of this paper is the quantum-mechanical solution of the three-quark model Hamiltonian describing baryons. In Jacobi coordinates, we use a harmonic oscillator basis for the transverse directions. For the longitudinal momentum fractions $x_i$, the pertinent basis follows from quantum mechanics in a “triangular cup” potential, which we solve exactly. We calculate the masses and light-front wave functions for the flavor symmetric ${\frac{3}{2}}^{+}$ baryons $bbb$, $ccc$, $sss$, $uuu$.

This is the third paper on hadronic light-front wave functions. We derive a light-front Hamiltonian from first principles, using the key features of the QCD vacuum at low resolution. In the first approximation, it gives transverse oscillator and longitudinal harmonic modes, and yields the correct Regge trajectories. For heavy quarkonia, we compare its spectrum to that obtained from the usual Schrödinger equation in the rest frame. We use the same approach for light quarks, and investigate the role of confinement and chiral symmetry breaking in the quark-antiquark sector. We then study spin-spin and spin-orbit mixing, resulting in e.g. quadrupole moments of vector mesons. For the light mesons, we show how to extend the famed ’t Hooft interaction to the light front, which solves the U(1) problem and helps produce a light pion. We use the ensuing light front wave functions to derive the pertinent parton distribution functions, parton amplitudes, and low energy constants.

This is the second paper on hadronic wave functions in the light-front formulation. We first consider only confinement effects, using the classical Nambu-Gotto string with massive end points in the light-cone gauge. We derive the light-front Hamiltonian and show how to solve it, using an expansion in suitable basis functions. We next discuss the correlators of Wilson lines on the light front, leading to an effective Hamiltonian that includes spin effects. At the end, we consider a separate problem of instanton-induced interactions, at the origin of the pion as a massless Goldstone mode on the light front.

This is the first of a sequence of papers that addresses the nonperturbative origin of the central and spin-dependent forces between quarks. Its main thrust is a focus on meson spectroscopy in the center-of-mass frame. We suggest a novel “dense instanton ensemble” model for the QCD vacuum, to explain the interquark forces in mesons, from quarkonia to heavy-light and light-light ones. The sequels will show how to export these interactions to the light front, and derive the corresponding Hamiltonians, mesonic, and baryonic light front wave functions. The ultimate aim of the series is to bridge the gap between hadronic spectroscopy and partonic observables.

We present a systematic study of ${\mathrm{\Lambda }}_c^{+}\to {\mathcal{B}}_q{\ell }^{+}{\nu }_{\ell }$ with ${\mathcal{B}}_q=(\mathrm{\Lambda },n)$ and $\ell =(e,\mu )$, examining all the possible decay observables based on the homogeneous bag model (HBM) and lattice QCD (LQCD). With the HBM, we find that the branching fractions and polarization asymmetries of the daughter baryon $\mathrm{\Lambda }$ are $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{e}^{+}{\nu }_e,\mathrm{\Lambda }{\mu }^{+}{\nu }_{\mu },n{\ell }^{+}{\nu }_{\ell })=(3.78\pm 0.25,3.67\pm 0.23,0.40\pm 0.04)\%$ and ${\alpha }_{\mathrm{\Lambda }}({\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{e}^{+}{\nu }_e,\mathrm{\Lambda }{\mu }^{+}{\nu }_{\mu })=(-82.6,-82.3)\%$, respectively. From the LQCD, we obtain that ${\alpha }_{\mathrm{\Lambda }}({\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{e}^{+}{\nu }_e,{\mu }^{+}{\nu }_{\mu })=(-87.4\pm 1.0,-87.2\pm 1.0)\%$. We also explore the time-reversal asymmetries due to new physics beyond the standard model. All our results are consistent with the current experimental data, while some of them are accessible to the experiments at BESIII and Belle II.

Condensed matter physics of gauge theories coupled to fermions can exhibit a rich phase structure, but are nevertheless very difficult to study in Monte Carlo simulations when they are afflicted by a sign problem. As an alternate approach, we use tensor network methods to explore the finite density physics of Abelian gauge theories without dynamical matter. As a concrete example, we consider the $U(1)$ gauge invariant quantum link ladder with spin-$\frac{1}{2}$ gauge fields in an external electric field, which causes the winding electric fluxes to condense in the ground state. We demonstrate how the electric flux tubes arrange themselves in the bulk, giving rise to crystalline patterns, whose period can be controlled by tuning the external field. We propose observables to detect the transitions in ground state properties not only in numerical experiments, but also in future cold-atom realizations. A systematic procedure for reaching the thermodynamic limit, as well as extending the studies from ladders to extended geometries is outlined.

The quantum dynamics of a self-gravitating thin matter shell in vacuum has been considered. The quantum Hamiltonian of the system is positive definite. Within a chosen set of parameters, the quantum shell bounces above the horizon. The considered quantum system does not collapse to the gravitational singularity of the corresponding classical system.

The quantization of the reduced phase-space of the Einstein-Hilbert action for gravity in $(2+1)\mathrm{D}$ has been shown to bring about the emergence, at the quantum level, of a topological quantum field theory endowed with an $S{U}_q(2)$ quantum group symmetry structure. We hereby tackle the same problem, but start from the kinematical $SU(2)$ (quantum) Hilbert space of the theory of $(2+1)\mathrm{D}$ gravity with a nonzero cosmological constant in the Palatini formalism, and subsequently impose the constraints. We hence show the dynamical emergence of the $S{U}_q(2)$ quantum group at the quantum level within the spin-foam framework. The regularized curvature constraint is responsible for the effective representations of $S{U}_q(2)$ that are recovered for any Wilson loop evaluated at the $SU(2)$ group element that encodes the discretization of the spacetime curvature induced by the cosmological constant. The extension to the spin-network basis, and consequently to any transition amplitude between its generic states, enables us to derive in full generality the recoupling theory of $S{U}_q(2)$. We provide constructive examples for the scalar product of two loop states and spin networks encoding trivalent vertices. We further comment on the diffeomorphism symmetry generated by the implementation of the curvature constraint, and finally we derive explicitly the partition function amplitude of the Turaev-Viro model.

We consider the gauge invariant version of the Proca theory, where besides the real vector field there is also the real scalar field. We quantize the theory such that the commutator of the scalar field operator and the electric field operator is given by a predefined three-dimensional vector field, say $\mathcal{E}$ up to a global prefactor. This happens when the field operators of the gauge invariant Proca theory satisfy the proper gauge constraint. In particular, we show that $\mathcal{E}$ given by the classical Coulomb field leads to the Coulomb gauge constraint making the vector field operator divergenceless. We also show that physically unreadable gauge constraints can have a strikingly simple $\mathcal{E}$-representation in our formalism. This leads to the discussion of Debye, Yukawa, etc. gauges. In general terms, we explore the mapping between classical vector fields and gauge constraints imposed on the operators of the studied theory.