We study the production of antineutrinos from the solar neutrinos due to Majorana neutrino decays of neutrino to antineutrino. Using the antineutrino spectra from KamLAND and Borexino, we present the newest limits on the lifetime of ${\nu }_3$ in this scenario. We consider ${\nu }_3\to {\overline{\nu }}_1+X$ and ${\nu }_3\to {\overline{\nu }}_2+X$ channels assuming scalar or pseudoscalar interactions. For hierarchical mass-splittings, we obtain the limits ${\tau }_3/m_3\ge 7\times {10}^{-5}\mathrm{s}/\mathrm{eV}$ and ${\tau }_3/m_3\ge 1\times {10}^{-5}\mathrm{s}/\mathrm{eV}$ for the two channels at 90% C.L. We found that the newest bound is five orders of magnitude better than the atmospheric and long-baseline bounds.

Lattice quantum chromodynamics calculations of multibaryon systems with physical quark masses would start a new age of ab initio predictions in nuclear physics. Performed on a finite grid, such calculations demand extrapolation of their finite-volume numerical results to free-space physical quantities. Such extraction of the physical information can be carried out fitting effective field theories (EFTs) directly to the finite-volume results or utilizing the Lüscher free-space formula or its generalizations for extrapolating the lattice data to infinite volume. To understand better the effect of periodic boundary conditions on the binding energy of few-nucleon systems we explore here light nuclei with physical masses in a finite box and in free space. The stochastic variational method is used to solve the few-body systems. Substantial optimizations of the method are introduced to enable efficient calculations in a periodic box. With the optimized code, we perform accurate calculations of light nuclei $A\le 4$ within leading-order pionless EFT. Using Lüscher formula for the two-body system, and its generalization for three- and four-body systems, we examine the box effect and explore possible limitations of these formulas for the considered nuclear systems.

We discuss the interplay between chiral and center sector phase transitions that occur in QCD with an imaginary quark chemical potential $\mu =i(2n+1)\pi T/3$. Based on a finite size scaling analysis in ($2+1$)-flavor QCD using highly improved staggered quark fermions with a physical strange quark mass and a range of light quark masses, we show that the endpoint of the line of first-order Roberge-Weiss (RW) transitions between center sectors is second order for light quark masses $m_l\ge m_s/320$, and that it belongs to the 3-d, $Z(2)$ universality class. The operator for the chiral condensate behaves like an energylike operator in an effective spin model for the RW phase transition. As a consequence, for any nonzero value of the quark mass, the chiral condensate will have an infinite slope at the RW phase transition temperature, $T_{\mathrm{RW}}$. Its fluctuation, the disconnected chiral susceptibility, behaves like the specific heat in $Z(2)$ symmetric models and diverges in the infinite volume limit at the RW phase transition temperature $T_{\mathrm{RW}}$ for any nonzero value of the light quark masses. Our analysis suggests the critical temperatures for the RW phase transition and the chiral phase transition coincide in the RW plane. On lattices with temporal extent $N_{\tau }=4$, we find in the chiral limit $T_{\chi }=T_{\mathrm{RW}}=195(1)\mathrm{MeV}$.

One can use more than one scale variable to define the family of surfaces in the space of parton splitting parameters that define the evolution of a parton shower. In an earlier paper, we developed this idea for electron-positron annihilation. Here, we use multiple scale variables for a parton shower with initial state partons. Then we need a more sophisticated analysis because the evolution of parton distribution functions must be coordinated with the parton shower evolution. We make the needed connections more precise than in our earlier work, even for the case of just one scale variable. Then we develop an example with three scale variables, which leads to advantages compared to the usual shower formulation with only one scale variable. We provide results for Drell-Yan muon pair production.

We apply the QCD sum rule method to systematically study the $S$- and $P$-wave fully strange tetraquark states within the diquark-antidiquark picture. We systematically construct their interpolating currents by explicitly adding the covariant derivative operator. Our results suggest that the $f_0(2100)$, $X(2063)$, and $f_2(2010)$ may be explained as the $S$-wave $ss\overline{s}\overline{s}$ tetraquark states with the quantum numbers $J^{PC}=0^{++}$, $1^{+-}$, and $2^{++}$, respectively. Our results also suggest that both the $X(2370)$ and $X(2500)$ may be explained as the $P$-wave $ss\overline{s}\overline{s}$ tetraquark states of $J^{PC}=0^{-+}$, and both the $\varphi (2170)$ and $X(2400)$ may be explained as the $P$-wave $ss\overline{s}\overline{s}$ tetraquark states of $J^{PC}=1^{--}$. The masses of the $ss\overline{s}\overline{s}$ tetraquark states with the exotic quantum number $J^{PC}=1^{-+}$ are extracted from two noncorrelated currents to be ${2.45}_{-0.25}^{+0.20}\mathrm{GeV}$ and ${2.49}_{-0.25}^{+0.21}\mathrm{GeV}$.

We investigate the three-dimensional (3D) and two-dimensional (2D) charge distributions of a spin-one particle in terms of the multipole expansion. On account of the geometrical difference between 2D and 3D spaces, projecting the 3D electric distribution to the 2D one in the Breit frame brings about the influence of the quadrupole distribution upon the monopole one. Thus, the 2D charge distribution becomes spin dependent. This effect should be sorted out from the relativistic effects arising from the Lorentz boost. We first provide the connections between the 2D and 3D distributions in the Breit frame in terms of the angle-dependent Abel transformation. We then provide the differential equations that enable us to map 2D distributions in the Breit frame to those in the infinite momentum frame.

The low-lying bottomoniumlike tetraquarks $b\overline{b}q\overline{q}$ ($q=u$, $d$, $s$) with spin-parity $J^P=0^{+}$, $1^{+}$, and $2^{+}$, and isospin $I=0$, 1, or $\frac{1}{2}$, are systematically investigated within the theoretical framework of real- and complex-scaling range of a chiral quark model, which has already been successfully applied in analysis of several multiquark systems. A complete four-body $S$-wave function, which includes meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color configurations are considered. In the $b\overline{b}q\overline{q}$ ($q=u$, $d$) tetraquark system, we found resonance states of $B^{(*)}{\overline{B}}^{(*)}$, $\mathrm{\Upsilon }\omega$, $\mathrm{\Upsilon }\rho$, and ${\eta }_b\rho$ nature with all possible $I(J^P)$ quantum numbers. Their masses are generally located in the energy range 11.0–11.3 GeV and their widths are less than 10 MeV. In addition, extremely narrow resonances, with two-meson strong decay widths less than 1.5 MeV, are obtained in both $b\overline{b}u\overline{s}$ and $b\overline{b}s\overline{s}$ tetraquark systems. Particularly, four radial excitations of $\mathrm{\Upsilon }{K}^{*}$ and ${\eta }_b{K}^{*}$ are found at $\sim 11.1\mathrm{GeV}$ in $J^P=0^{+}$, $1^{+}$, and $2^{+}$ channels of $b\overline{b}u\overline{s}$ system. One $\mathrm{\Upsilon }(1S)\varphi (2S)$ resonance state is obtained at 11.28 GeV in the $J^P=1^{+}$ sector.

The new measurement of the $W$-boson mass from the CDF Collaboration shows a significant tension with the Standard Model prediction. We quantify this discrepancy within a state-of-the-art analysis of electroweak precision data and scrutinize the leading deformations of the Standard Model effective field theory arising at dimension six. We find evidence for a nonzero value of the $T$ parameter, i.e., for a novel source of violation of custodial symmetry, pointing to physics beyond the Standard Model at the $4.5\sigma$ level. We contextualize the implications of our findings in light of other present anomalies in particle physics.

The upcoming electron-ion collider (EIC) will address several outstanding puzzles in modern nuclear physics. Topics such as the partonic structure of nucleons and nuclei, the origin of their mass and spin, among others, can be understood via the study of high-energy electron-proton ($ep$) and electron-nucleus ($eA$) collisions. Achieving the scientific goals of the EIC will require a novel electron-hadron collider and detectors capable to perform high-precision measurements but also dedicated tools to model and interpret the data. To aid in the latter, we present a general-purpose $eA$ Monte Carlo generator—BeAGLE. In this paper, we provide a general description of the models integrated into BeAGLE, applications of BeAGLE in $eA$ physics, implications for detector requirements at the EIC, and the tuning of the parameters in BeAGLE based on available experimental data. Specifically, we focus on a selection of model and data comparisons in particle production in both $ep$ and $eA$ collisions, where baseline particle distributions provide essential information to characterize the event. In addition, we investigate the collision geometry determination in $eA$ collisions, which could be used as an experimental tool for varying the nuclear density.

Motivated by Sen’s spacetime prescription for the construction of theories with self-dual field strengths, we present a rigid superspace Lagrangian describing noninteracting tensor multiplets living on a stack of M5-branes and containing all the physical constraints on the fields, yielding the on-shell matching of the degrees of freedom. The geometric superspace approach adopted here offers a natural realization of superdiffeomorphisms and is particularly well suited for the coupling to supergravity. However, within this formulation the (anti-)self-duality property of the 3-form field strengths is lost when the superspace Lagrangian is trivially restricted to spacetime. We propose two main paths to address this issue: a first-order superspace extension of Sen’s spacetime results, which, once trivially restricted to spacetime, yields all the dynamical equations including the (anti-)self-duality constraint on the 3-form field strengths, and a possible way to obtain a full superspace description of the theory, based on integral forms.

We use the continued fraction method to determine the eigenfrequencies associated with a scalar field around a Kerr-like black hole. The Kerr-like metric considered in this article is a subclass of the general parametrization of axisymmetric black holes proposed by Konoplya et al. In addition to its mass $M$ and specific angular momentum $a$, the black hole depends on a third parameter $\eta$, called the deformation parameter. We investigate how the deformation parameter affects the quasinormal modes and the quasibound states of a massive scalar field around the black hole. In particular, we compute the timescales associated with the superradiant instabilities of the scalar field in such a spacetime. The properties of stationary scalar clouds that could be formed by these instabilities are also discussed.

We report the existence of a ghost- and tachyon-free sector in metric affine theories of gravity, that is invariant under diffeomorphism and a particular Abelian symmetry. In contrast with many studied cases in the literature, the constraints for unitarity and causality are granted by nonaccidental symmetries and do not ask for further tuning, whose fate under renormalization would be unclear. Unsurprisingly, the minimal model is massless. We find that a mechanism to provide mass is accommodated by a simple Stueckelberg extension of metric affine gravity involving the nonmetricity tensor. A nontrivial result is that also such an extension describes a ghost- and tachyon-free dynamic stabilized by the same Abelian symmetry. The resulting spectrum of the collective rank-3, rank-2, and rank-0 Lagrangian is investigated with the operators recently computed in the literature.

The relationship between thermodynamics and the Lloyd bound on the holographic complexity for a black hole has been of interest. We consider $D$ dimensional anti–de Sitter black holes with hyperbolic geometry as well as black holes with momentum relaxation that have minimum values for the temperature and the mass. We will show that the singular points of the thermodynamic curvature of the black holes, as thermodynamic systems, correspond to the zero points of the action and volume complexity at the Lloyd bound. For such black holes with a single horizon, the rates of growth of the complexity of volume and the complexity of action at minimum mass and minimum temperature are zero, respectively. We show that the thermodynamic curvature diverges at these minimal values. Because of the behavior of the growth rate of the action complexity and thermodynamic curvature at minimum temperature, we propose the growth rate of the action complexity as an order parameter of the black holes as the thermodynamic systems. Also, we derive the critical exponent related to the thermodynamic curvature in different dimensions.

We consider diffeomorphism violation, which is parametrized by nondynamical background fields of the gravitational Standard-Model Extension, and study its effects on the time evolution of the Universe. Our goal is to identify background field configurations that imply stages of accelerated expansion without exotic forms of matter and radiation present. Although our approach gives rise to a set of restrictive conditions, configurations are encountered that exhibit this property or show other interesting behaviors. The findings of our article, which is among the first to apply the Standard-Model Extension to a cosmological setting, provide an initial understanding of how to technically incorporate background fields into the cosmological evolution equations and what their phenomenological impact may be.

We investigate the existence of vortex configurations in two gauged-$CP(2)$ models extended via the inclusion of magnetic impurities. In particular, we consider both the Maxwell-$CP(2)$ and the Chern-Simons-$CP(2)$ enlarged scenarios, separately. We choose a $CP(2)$-field configuration with a null topological charge not only in the simplest (free) case, but also when coupled to an Abelian gauge field. The implementation of the Bogomol’nyi-Prasad-Sommerfield (BPS) formalism shows that the effective models for such a configuration possess a self-dual structure which looks like those inherent to the gauged sigma models. Therefore, when the $CP(2)$ field is coupled to the Maxwell term, the corresponding total energy possesses both a well-defined Bogomol’nyi bound and a quantized magnetic flux. Further, when the $CP(2)$ scenario is gauged with the Chern-Simons action, the total electric charge is verified to be proportional to the quantized magnetic flux. In addition, the analysis verifies that the magnetic impurity contributes to the BPS potentials and appears in both of the models’ BPS equations. Next, we introduce a Gaussian-type impurity and solve the self-dual equations via a finite-difference scheme. The resulting solutions present a nonmonotonic behavior that flips both the magnetic and electric fields. Finally, we discuss the topologically trivial solutions in the limit for which the impurity becomes a Dirac $\delta$ function.

Semiconductors with $\mathcal{O}(\mathrm{meV})$ band gaps have been shown to be promising targets to search for sub-MeV mass dark matter (DM). In this paper we focus on a class of materials where such narrow band gaps arise naturally as a consequence of spin-orbit coupling (SOC). Specifically, we are interested in computing DM-electron scattering and absorption rates in these materials using state-of-the-art density functional theory techniques. To do this, we extend the DM interaction rate calculation to include SOC effects which necessitates a generalization to spin-dependent wave functions. We apply our new formalism to calculate limits for several DM benchmark models using an example ${\text{ZrTe}}_5$ target and show that the inclusion of SOC can substantially alter projected constraints.

We compute the single-spin asymmetry $A_{\mathrm{UL}}$ in semi-inclusive deep-inelastic scattering of unpolarized leptons and longitudinally polarized protons at a large transverse momentum of the produced hadron. Our calculation is performed in collinear factorization at the lowest order of QCD perturbation theory. For photon exchange, the asymmetry is $T$-odd and receives contributions from the interference of the tree level and one-loop absorptive amplitudes. We consider the behavior of the spin asymmetry at low transverse momentum where contact to the formalism based on transverse momentum dependent distribution functions can be made. We also present some phenomenological results relevant for the COMPASS and HERMES experiments and the future Electron-Ion Collider.

We investigate properties of the ground-state and first radially excited four-quark mesons $X_0$ and $X_0^{\prime }$ with a diquark-antidiquark structure $[ud][\overline{c}\overline{s}]$ and spin-parities $J^{\mathrm{P}}=0^{+}$. Our aim is to reveal whether or not one of these states can be identified with the resonance $X_0(2900)$, recently discovered by the LHCb Collaboration. We model $X_0$ and $X_0^{\prime }$ as tetraquarks composed of either axial-vector or scalar diquark and antidiquark pairs. Their spectroscopic parameters are computed by employing the QCD two-point sum rule method and including vacuum condensates up to dimension 15 in the analysis. For an axial-axial structure of $X_0^{(\prime )}$, we find partial widths of the decays $X_0^{(\prime )}\to D^{-}{K}^{+}$ and $X_0^{(\prime )}\to D^0{K}^0$, and estimate full widths of the states $X_0^{(\prime )}$. To this end, we calculate the strong couplings at the vertices $X_0^{(\prime )}DK$ in the framework of the light-cone sum rule method. We also use technical approaches of the soft-meson approximation necessary to analyze tetraquark-meson-meson vertices. We obtain $m=(2545\pm 160)\mathrm{MeV}$ and $m^{\prime }=(3320\pm 120)\mathrm{MeV}$ [$m_{\mathrm{S}}=(2663\pm 110)\mathrm{MeV}$ and $m_{\mathrm{S}}^{\prime }=(3325\pm 85)\mathrm{MeV}$ for a scalar-scalar current] for the masses of the particles $X_0$ and $X_0^{\prime }$, as well as estimates for their full widths ${\mathrm{\Gamma }}_0=(140\pm 29)\mathrm{MeV}$ and ${\mathrm{\Gamma }}_0^{\prime }=(110\pm 25)\mathrm{MeV}$, which allow us to interpret that neither is the resonance $X_0(2900)$. At the same time, these predictions provide important information about the ground-state and radially excited diquark-antidiquark structures $X_0$ and $X_0^{\prime }$, which should be objects of future experimental and theoretical studies.

The propagation properties of spin degrees of freedom are analyzed in the framework of relativistic hydrodynamics with spin based on the de Groot van Leeuwen–van Weert definitions of the energy-momentum and spin tensors. We derive the analytical expression for the spin wave velocity for arbitrary statistics and show that it goes to half the speed of light in the ultrarelativistic limit. We find that only the transverse degrees of freedom propagate, analogously to electromagnetic waves. Finally, we consider the effect of dissipative corrections and calculate the damping coefficients for the case of Maxwell-Jüttner statistics.

We report results from the first search for the rare penguin-dominated decay mode $B^0\to K_S^0{K}_S^0\gamma$, which can result from the production of tensor mesons $f(1270)$ and $f^{\prime }(1525)$ in association with a photon. The search uses the full data sample of $772\times {10}^{6}B\overline{B}$ pairs collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. No statistically significant signals are observed in the $K_S^0{K}_S^0$ invariant mass range $1\mathrm{GeV}/c^2<M_{K_S^0{K}_S^0}<3\mathrm{GeV}/c^2$, and the following upper limits at the 90% confidence level are obtained: $\mathcal{B}(B^0\to K_S^0{K}_S^0\gamma )<5.8\times {10}^{-7}$, $\mathcal{B}(B^0\to f_2\gamma )\times \mathcal{B}(f_2(1270)\to K_S^0{K}_S^0)<3.1\times {10}^{-7}$, and $\mathcal{B}(B^0\to f_2^{\prime }\gamma )\times \mathcal{B}(f_2^{\prime }(1525)\to K_S^0{K}_S^0)<2.1\times {10}^{-7}$. In addition, 90% confidence-level upper limits in the range of $[0.7–2.9]\times {10}^{-7}$ are also obtained on the $B^0\to K_S^0{K}_S^0\gamma$ branching fraction in bins of $M_{K_S^0{K}_S^0}$.