We present the first calculation in lattice QCD of the process $\gamma K\to K\pi$ in which the narrow $K^{*}$ vector resonance appears. Using a lattice on which the pion has a mass of 284 MeV, we determine the transition amplitude at 128 points in the $(Q^2,E_{K\pi })$ plane, and find suitable resonant scattering descriptions. We demonstrate the need to account for $S$-wave $K\pi$ elastic scattering when converting the finite-volume matrix elements computed in lattice QCD to the physically relevant infinite-volume matrix elements, even when we are primarily interested in the $P$-wave amplitude. Analytically continuing parametrizations of the $\gamma K\to K\pi$ amplitude to the $K^{*}$ resonance pole, we obtain the $K^{*+}\to K^{+}\gamma$ transition form factor and compare the $Q^2=0$ value to the corresponding value extracted from the experimental partial decay width.

The canonical quantization method for collective coordinates in crystalline configurations of the generalized Skyrme model is applied in order to find the quantum ground state of skyrmion crystals and study the quantum corrections to the binding energy resulting from the isospin degrees of freedom. This leads to a consistent description of asymmetric nuclear matter within the Skyrme framework and allows us to compute the symmetry energy of the skyrmionic crystal as a function of the baryon density and to compare with recent observational constraints.

In this paper, we make a detailed study on the hadronic production of the ${\mathrm{\Xi }}_{bc}$ baryon at a fixed-target experiment at the LHC (AFTER@LHC). In estimating the production cross sections, the ($g+g$), ($g+c$), and ($g+b$) production mechanisms are considered. For the initial heavy quarks, in addition to the extrinsic component, we also consider the intrinsic component. It is found that the ($g+c$) and ($g+b$) production mechanisms give sizable contributions to the ${\mathrm{\Xi }}_{bc}$ production, and the ($g+b$) mechanism dominates the production. The results show that there are about $3.40\times {10}^5$ ${\mathrm{\Xi }}_{bc}$ events that can be produced per year at the AFTER@LHC if the integrated luminosity of the AFTER@LHC can be up to $2{\mathrm{fb}}^{-1}$ per year. Moreover, the intrinsic heavy quarks can have a significant impact on production, which inversely makes the intrinsic component be possibly tested at the AFTER@LHC.

Motivated by the precision measurements of heavy flavor baryon masses, we analyze the modification of quark charge by employing the screening effect inside the baryon. In addition, we calculate the isospin mass splitting up to charmed baryons employing isospin symmetry breaking. Consequently, we obtain the masses, magnetic moments, and transition moments of $J^P={\frac{1}{2}}^{+}$ and ${\frac{3}{2}}^{+}$ baryons to predict radiative decay widths for ${\frac{1}{2}}^{\prime +}\to {\frac{1}{2}}^{+}$ and ${\frac{3}{2}}^{+}\to {\frac{1}{2}}^{(\prime )+}$ transitions. Finally, we include the effects of state mixing in flavor degenerate baryon magnetic and transition moments, as well as $M1$ transition decay widths.

We revisit the status of asymptotic symmetries in higher even dimensions and propose a definition of superrotation charge beyond linearized gravity. We prove that there is a well-defined spacetime action of the superrotation charge on the space of asymptotically flat geometries. Additionally, we demonstrate that the Ward identity associated with superrotation charges follows from the subleading soft graviton theorem, which is a universal constraint (in $d>4$) along with the leading soft graviton theorem.

Motion of a point charge emitting radiation in an electromagnetic field obeys the Abraham–Lorentz–Dirac equation, with the effects of radiation reaction or self-force incorporated. This class of equations describing backreaction, including also the equations for gravitational self-force or Einstein’s equation for cosmology driven by trace anomaly, contains third-order derivative terms. They are known to have pathologies like the possession of runaway solutions, causality violation in preacceleration, and the need for an extra second-order derivative initial condition. In our current program we reexamine this old problem from a different perspective, that of non-Markovian dynamics in open systems. This conceptual and technical framework has been applied earlier to the study of backreaction of quantum field effects on charge and mass motions and in early universe cosmology. Here we consider a moving atom whose internal degrees of freedom, modeled by a harmonic oscillator, are coupled to a scalar field in the same manner as in scalar electrodynamics. Due to the way it is coupled to the charged particle, the field acts effectively like a supra-Ohmic environment, although the field itself actually has an Ohmic spectral density. We thus have cast the problem of radiation reaction to a study of the non-Markovian dynamics of a Brownian oscillator in a supra-Ohmic environment. Our analysis shows that (a) there is no need for specifying a second derivative for the initial condition, and (b) there is no preacceleration. These undesirable features in conventional treatments arise from an inconsistent Markovian assumption: these equations were regarded as Markovian ab initio, not as a limit of the backreaction-imbued non-Markovian equation of motion. If one starts with the full non-Markovian dynamical equation and takes the proper Markovian limit judiciously, no harms are done. Finally, c) there is no causal relation between the higher-derivative term in the equation of motion and the existence of runaway solutions. The runaway behavior is a consequence that the memory time in the environment is shorter than a critical value, which in the case of the charged particle is the classical charge radius. If the charge has an effective size greater than this critical value, its dynamics is stable. When this reasonable condition is met, radiation reaction understood and treated correctly in the non-Ohmic non-Markovian dynamics still obeys a third-order derivative equation, but it does not require a second derivative initial condition, and there is no preacceleration.

We study classical scalar fields in asymptotically Lifshitz spacetimes. By evading Derrick’s theorem requiring the scalar potential to explicitly depend on the background coordinates, we induce a diffeomorphism invariance breaking and settle a formalism to find spatially localized solutions in the probe field limit. By inserting a backreaction equipped with a cosmological constant and a Maxwell term coupled to a dielectric function in the model, we find a Lifshitz black hole solution.

The scalar field theory with potential $V(\phi )=\frac{1}{2}{m}^2{\phi }^2-\frac{1}{4}g{\phi }^4$ ($g>0$) is ill defined as a Hermitian theory but in a non-Hermitian $\mathcal{P}\mathcal{T}$-symmetric framework it is well defined, and it has a positive real energy spectrum for the case of spacetime dimension $D=1$. While the methods used in the literature do not easily generalize to quantum field theory, in this paper the path-integral representation of a $\mathcal{P}\mathcal{T}$-symmetric $-g{\phi }^4$ theory is shown to provide a unified formulation for general $D$. A new conjectural relation between the Euclidean partition functions $Z^{\mathcal{P}\mathcal{T}}(g)$ of the non-Hermitian $\mathcal{P}\mathcal{T}$-symmetric theory and $Z_{\text{Herm}}(\lambda )$ of the $\lambda {\phi }^4$ ($\lambda >0$) Hermitian theory is proposed: $\log Z^{\mathcal{P}\mathcal{T}}(g)=\frac{1}{2}\log Z_{\text{Herm}}(-g+\mathrm{i}{0}^{+})+\frac{1}{2}\log Z_{\text{Herm}}(-g-\mathrm{i}{0}^{+})$. This relation ensures a real energy spectrum for the non-Hermitian $\mathcal{P}\mathcal{T}$-symmetric $-g{\phi }^4$ field theory. A closely related relation is rigorously valid in $D=0$. For $D=1$, using a semiclassical evaluation of $Z^{\mathcal{P}\mathcal{T}}(g)$, this relation is verified by comparing the imaginary parts of the ground-state energy $E_0^{\mathcal{P}\mathcal{T}}(g)$ (before cancellation) and $E_{0,\mathrm{Herm}}(-g\pm \mathrm{i}{0}^{+})$.

We show that, in relativistic field theories, the thermal correlation function of $N$ bosonic operators $⟨{\mathcal{O}}_1(x_1,t_1){\mathcal{O}}_2(x_2,t_2)\dots {\mathcal{O}}_N(x_N,t_N){⟩}_T$ at sufficiently spacelike-separated points shows exponentially weak dependence on the time variables $t_1,\dots ,t_N$, when the space separations are held fixed. For classical thermal field theory, the time dependence vanishes when all points are spacelike separated.

We present a “primitive” way of realizing finite-mass Dirac monopoles in $U(1)$ gauge theories involving a single nonminimally interacting scalar field. Typically, the energy density of this type of monopole is not concentrated at its core, but it is distributed in a spherical shell, as we illustrate on several exact solutions in the Bogomol’nyi-Prasad-Sommerfield limit. We show that our construction can be interpreted as a limit of infinitely massive $W$ bosons coupled to electromagnetic field strength via a dipole moment. Combining our approach with ideas of Weinberg and Lee, we present a general landscape of $U(1)$ gauge models that support a finite-mass Dirac monopole. In fact, all classical monopoles, i.e., Wu-Yang, ’t Hooft-Polyakov, Cho-Maison, etc., are special points on this landscape.

We construct and explore the solution space of two nonspinning, miniboson stars in equilibrium, in fully nonlinear general relativity (GR), minimally coupled to a free, massive, complex scalar field. The equilibrium is due to the balance between the (long range) gravitational attraction and the (short-range) scalar mediated repulsion, the latter enabled by a $\pi$ relative phase. Gravity is mandatory; it is shown no similar solutions exist in flat spacetime, replacing gravity by nonlinear scalar interactions. We study the variation of the proper distance between the stars with their mass (or oscillation frequency), showing it can be qualitatively captured by a simple analytic model that features the two competing interactions.

The Schrödinger-Newton model describes self-gravitating quantum particles, and it is often cited to explain the gravitational collapse of the wave function and the localization of macroscopic objects. However, this model is completely nonrelativistic. Thus, in order to study whether the relativistic effects may spoil the properties of this system, we derive a modification of the Schrödinger-Newton equation by considering certain relativistic corrections up to the first post-Newtonian order. The construction of the model begins by considering the Hamiltonian of a relativistic particle propagating on a curved background. For simplicity, the background metric is assumed to be spherically symmetric, and it is then expanded up to the first post-Newtonian order. After performing the canonical quantization of the system, and following the usual interpretation, the square of the module of the wave function defines a mass distribution, which in turn is the source of the Poisson equation for the gravitational potential. As in the nonrelativistic case, this construction couples the Poisson and the Schrödinger equations and leads to a complicated nonlinear system. Hence, the dynamics of an initial Gaussian wave packet is then numerically analyzed. We observe that the natural dispersion of the wave function is slower than in the nonrelativistic case. Furthermore, for those cases that reach a final localized stationary state, the peak of the wave function happens to be located at a smaller radius. Therefore, the relativistic corrections effectively contribute to increase the self-gravitation of the particle and strengthen the validity of this model as an explanation for the gravitational localization of the wave function.

A subfraction of dark matter or new particles trapped inside celestial objects can significantly alter their macroscopic properties. We investigate the new physics imprint on celestial objects by using a generic framework to solve the Tolman-Oppenheimer-Volkoff (TOV) equations for up to two fluids. We test the impact of populations of new particles on celestial objects, including the sensitivity to self-interaction sizes, new particle mass, and net population mass. Applying our setup to neutron stars and boson stars, we find rich phenomenology for a range of these parameters, including the creation of extended atmospheres. These atmospheres are detectable by their impact on the tidal Love number, which can be measured at upcoming gravitational wave experiments such as Advanced LIGO, the Einstein Telescope, and LISA. We release our calculation framework as a publicly available code, allowing the TOV equations to be generically solved for arbitrary new physics models in novel and admixed celestial objects.

Warm dark matter (WDM) can potentially explain small-scale observations that currently challenge the cold dark matter (CDM) model, as warm particles suppress structure formation due to free-streaming effects. Observing small-scale matter distribution provides a valuable way to distinguish between CDM and WDM. In this work, we use observations from the Dark Energy Survey and PanSTARRS1, which observe 270 Milky-Way satellites after completeness corrections. We test WDM models by comparing the number of satellites in the Milky Way with predictions derived from the Semi-Analytical SubHalo Inference Modeling (sashimi) code, which we develop based on the extended Press-Schechter formalism and subhalos’ tidal evolution prescription. We robustly rule out WDM with masses lighter than 4.4 keV at 95% confidence level for the Milky-Way halo mass of ${10}^{12}{M}_{\odot }$. The limits are a weak function of the (yet uncertain) Milky-Way halo mass, and vary as $m_{\mathrm{WDM}}\gtrsim 3.6–5.1\mathrm{keV}$ for $(0.6–2.0)\times {10}^{12}{M}_{\odot }$. For the sterile neutrinos that form a subclass of WDM, we obtain the constraints of $m_{{\nu }_s}>12\mathrm{keV}$ for the Milky-Way halo mass of ${10}^{12}{M}_{\odot }$, independent of the mixing angle. These results based on sashimi do not rely on any assumptions of galaxy formation physics or are not limited by numerical resolution. The models, therefore, offer a robust and fast way to constrain the WDM models. By applying a satellite forming condition, however, we can rule out the WDM mass lighter than 9.0 keV for the Milky-Way halo mass of ${10}^{12}{M}_{\odot }$.

We investigate the escape process of cosmic rays (CRs) from perpendicular shock regions of a spherical shock propagating to a circumstellar medium with the Parker-spiral magnetic field. The diffusive shock acceleration in perpendicular shocks of supernova remnants (SNRs) is expected to accelerate CRs up to PeV without upstream magnetic field amplification. Red supergiants (RSGs) and Wolf-Rayet (WR) stars are considered as progenitors in this work. We perform test particle simulations to investigate the escape process and escape-limited maximum energy without magnetic field amplification in the upstream region, where the magnetic field strength and rotation period expected from observations of RSGs and WR stars are used. We show that particles escape to the far upstream region while moving along the equator or poles and the maximum energy is about 10–100 TeV when SNRs propagate to free wind regions of RSGs and WR stars. In most cases, the escape-limited maximum energy is given by the potential difference between the equator and pole. If progenitors are oblique rotators and SNRs are in the early phase just after the supernova explosion, the escape-limited maximum energy is limited by the half wavelength of the wavy current sheet. In addition, for RSGs, we show that the luminosity of CRs accelerated in the wind region is sufficient to supply the observed CR flux above 10 TeV if a strong magnetic field strength is sustained in most RSGs. In terms of the CR luminosity, SNRs propagating to the free wind of WR stars can contribute to PeV CRs. As long as no magnetic field amplification works around SNR shocks, the maximum energy is decided by the magnetic field strength in the wind region, which depends on the rotation period, stellar wind, and surface magnetic field of RSGs and WR stars. Therefore, we need to observe these quantities to understand the origin of CRs.

We formulate the field-space geometry for an effective field theory of scalars and gauge bosons. Geometric invariants such as the field-space curvature enter in both scattering amplitudes and the renormalization group equations, with the scalar and gauge results unified in a single expression.

We construct the effective potentials of the $P_{\psi }^N$ and $P_{\psi s}^{\mathrm{\Lambda }}$ states based on the ${\mathrm{SU}(3)}_{\mathrm{f}}$ symmetry and heavy quark symmetry. Then we perform the coupled-channel analysis of the lowest-isospin $P_{\psi }^N$ and $P_{\psi s}^{\mathrm{\Lambda }}$ systems. The coupled-channel effects play different roles in the $P_{\psi }^N$ and $P_{\psi s}^{\mathrm{\Lambda }}$ systems. In the $P_{\psi }^N$ systems, this effect gives minor corrections to the masses of the $P_{\psi }^N$ states. In the $P_{\psi s}^{\mathrm{\Lambda }}$ system, the ${\mathrm{\Lambda }}_c{\overline{D}}_s-{\mathrm{\Xi }}_c\overline{D}$ coupling will shift the mass of the $P_{\psi s}^{\mathrm{\Lambda }}(4338{)}^0$ close to the ${\mathrm{\Xi }}_c\overline{D}$ threshold. The ${\mathrm{\Lambda }}_c{\overline{D}}_s^{(*)}-{\mathrm{\Xi }}_c{\overline{D}}^{(*)}$ coupling will also produce extra $P_{\psi s}^{\mathrm{\Lambda }}$ states. We discuss the correspondence between the $P_{\psi }^N$ and $P_{\psi s}^{\mathrm{\Lambda }}$ states. Our results prefer that the SU(3) partners of the observed $P_{\psi }^N(4312{)}^{+}$, $P_{\psi }^N(4440{)}^{+}$, and $P_{\psi }^N(4457{)}^{+}$ in the $P_{\psi s}^{\mathrm{\Lambda }}$ system not have been found yet.

Two Higgs doublet models (2HDMs) are attractive scenarios for physics beyond the Standard Model. In particular, lepton-specific manifestations remain contenders to explain the observed discrepancy between the anomalous magnetic moment of the muon $a_{\mu }$ predicted within the Standard Model and recent observations at Fermilab and BNL. Dominant uncertainties that affect $a_{\mu }$ have motivated the MUonE experiment to access the hadronic vacuum polarization contribution that impacts $a_{\mu }$ via elastic muon-electron scattering. In this work, we contrast the high precision that is achievable within the MUonE context with constraints from flavor physics, precision electroweak constraints and LHC searches as well as their extrapolations for a range of two Higgs doublet models with a softly broken ${\mathbb{Z}}_2$ symmetry. We find that the sensitivity of MUonE does not extend beyond the parameter regions that are already excluded by other constraints. MUonE will therefore provide a detailed measurement of the hadronic vacuum polarization contribution which then transparently informs $a_{\mu }$ interpretations in 2HDMs without modifications of correlations from beyond the Standard Model interactions. In passing we extend earlier results of LHC and flavor projections to lepton-specific 2HDM (Types X and Y) scenarios, and comment on the possibility of modifying the value of the $W$-boson mass; we briefly discuss the implications for a strong first-order electroweak phase transition for these models.

By adopting a methodology proposed by R. J. Adler et al., we study the interesting analogy between the fermion-gravity and the fermion-electromagnetic interactions in the presence of the minimal Lorentz-violating (LV) fermion coefficients. The single-fermion matrix elements of gravitational interaction (SMEGI) are obtained with a prescribed Lense-Thirring (LT) metric assuming test particle assumption. Quite distinct from the extensively studied linear gravitational potential, the LT metric is essentially curved and thus reveals the anomalous LV matter-gravity couplings as a manifestation of the so-called gravito-magnetic effects, which go beyond the conventional equivalence principle predictions. By collecting all the spin-dependent operators from the SMEGI with some reasonable assumptions, we get a LV nonrelativistic Hamiltonian, from which we derive the anomalous spin precession and gravitational acceleration due to LV. By combining these results with certain spin gravity experiments, we get some rough bounds on several LV coefficients, such as $|3\overrightarrow{\tilde{H}}-2\overrightarrow{b}|\le 1.46\times {10}^{-5}\mathrm{GeV}$, with some ad hoc assumptions.