It is demonstrated that the generic four-dimensional Taub-Newman-Unti-Tamburino (Taub-NUT) spacetimes can be perfectly described in terms of three or four different kinds of thermodynamic hairs: the Komar mass ($M=m$), the “angular momentum” ($J_n=mn$), the gravitomagnetic charge ($N=n$), and/or the dual (magnetic) mass ($\tilde{M}=n$). In other words, the NUT charge is a thermodynamic multihair which means that it simultaneously has both rotation-like and electromagnetic charge-like characteristics; this is in sharp contrast with the previous knowledge that it has only one physical feature, or that it is purely a single solution parameter. To arrive at this novel result, we put forward a simple, systematic way to investigate the consistent thermodynamic first law and Bekenstein-Smarr mass formulas of all four-dimensional spacetimes that contain a nonzero NUT charge, facilitated by first deriving a meaningful Christodoulou-Ruffini-type squared-mass formula. In this way, not only can the elegant Bekenstein-Hawking one-quarter area-entropy relation be naturally restored in the Lorentzian and Euclidian sectors of generic Taub-NUT-type spacetimes without imposing any constraint condition, but also the physical meaning of the NUT parameter as a poly-facet can be completely clarified in the thermodynamic sense for the first time.

We estimate the beam-normal single-spin asymmetry in elastic lepton-proton scattering without employing the ultrarelativistic approximation. Our calculation is relevant for analyses of muon scattering at energies of a few hundred mega-electron-volts and below—when effects of the muon mass become essential. At such energies, the transverse polarization of the muon beam is expected to contribute significantly to the systematic uncertainty of precision measurements of elastic muon-proton scattering. We evaluate such systematics using an example of the MUSE experiment at PSI. The muon asymmetry is estimated at about 0.1% in kinematics of MUSE, and it is the largest for scattering into a backward hemisphere.

Recently, a novel phenomenon is observed for vacuum decay to proceed via classically allowed dynamical evolution from initial configurations of false vacuum fluctuations. With the help of some occasionally developed large fluctuations in time derivative of a homogeneous scalar field that is initially sitting at the false vacuum, the flyover vacuum decay is proposed if the initial Gaussian profile of field velocity contains a spatial region where the field velocity is large enough to flyover the potential barrier. In this paper, we point out that, even if the initial profile of field velocity is nowhere to be large enough to classically overcome the barrier, the semiclassical vacuum decay could still be possible if the initial profile of field velocity extends over large enough region.

We construct a Lorentz-violating electrodynamics in ($1+2$) spacetime dimensions from the electromagnetic sector of the nonminimal standard model extension (SME) in ($1+3$) dimensions. Subsequently, we study some of the basic properties of this framework. We obtain the field equations, the Green’s functions, and the perturbative Feynman rules. Furthermore, the modified dispersion relations are computed at leading order in Lorentz violation. We then remove the unphysical degrees of freedom from the electromagnetic Green’s function that are present due to gauge invariance. The resulting object is used to construct the general solutions of the uncoupled field equations with external inhomogeneities present. This modified planar electrodynamics may be valuable to describe electromagnetic phenomena in two-dimensional condensed-matter systems. Furthermore, it supports a better understanding of the electromagnetic sector of the nonminimal SME.

We propose a viable theory based on the $SU(3{)}_C\times SU(3{)}_L\times U(1{)}_X$ gauge group supplemented by the $S_4$ discrete group together with other various symmetries, whose spontaneous breaking gives rise to the current Standard Model (SM) fermion mass and mixing hierarchy. In the proposed theory the small light active neutrino masses are generated from a linear seesaw mechanism mediated by three Majorana neutrinos. The model is capable of reproducing the experimental values of the physical observables of both quark and lepton sectors. Our model is predictive in the quark sector having 9 effective parameters that allow to successfully reproduce the four Cabbibo-Kobayashi-Maskawa parameters and the six SM quark masses. In the SM quark sector, there is particular scenario, motivated by naturalness arguments, which allows a good fit for its ten observables, with only six effective parameters. We also study the single heavy scalar production via gluon fusion mechanism at a proton-proton collider. Our model is also consistent with the experimental constraints arising from the Higgs diphoton decay rate.

We present lattice QCD results for mesonic screening masses in the temperature range $140\mathrm{MeV}\lesssim T\lesssim 2500\mathrm{MeV}$. Our calculations were carried out using ($2+1$) flavors of the highly improved staggered quark action, with a physical value for the strange quark mass and two values of the light quark mass corresponding to pion masses of 160 and 140 MeV. Continuum-extrapolated results were obtained using calculations with a variety of lattice spacings corresponding to temporal lattice extents $N_{\tau }=6–16$. We discuss the implications of these results for the effective restoration of various symmetries in the high temperature phase of QCD, as well as the approach toward the perturbative limit.

Using the infinite-volume photon propagator, we develop a method which allows us to calculate electromagnetic corrections to stable hadron masses at leading order in ${\alpha }_{\mathrm{QED}}$ with only exponentially suppressed finite-volume effects. The key idea is that the infinite-volume hadronic current-current correlation function with large time separation between the two currents can be reconstructed by its value at modest time separation, which can be evaluated in finite volume with only exponentially suppressed errors. This approach can be extended to other possible applications such as QED corrections to (semi)leptonic decays and some rare decays.

We revisit the predictions for the pseudoscalar-photon transition form factors in bottom-up and top-down holographic QCD models which only use the pion decay constant and the $\rho$ meson mass as input. We find remarkable agreement with the available experimental data for the single-virtual ${\pi }^0$ form factor that have recently been extended to lower momenta by BESIII, down to $0.3{\mathrm{GeV}}^2$. The bottom-up models moreover turn out to be roughly consistent with recent experimental results obtained by BABAR for the double-virtual ${\eta }^{\prime }$ form factor at large momenta as well as with dispersion theory results and a recent lattice extrapolation for the double-virtual ${\pi }^0$ form factor. Calculating the pion pole contribution to the hadronic light-by-light scattering in the anomalous magnetic moment of the muon, we find that the bottom-up models in question span the range $a_{\mu }^{{\pi }^0}=5.9(2)\times {10}^{-10}$, which is about 10% lower than estimated previously by approximating these holographic predictions through simple interpolators.

We derive general properties of the scale-dependent effective spectral dimensions of non-perturbative gauge boson propagators as they appear as solutions from different methods in Yang-Mills theories. In the ultraviolet and for short timescales the anomalous dimensions of the propagators lead to a slight decrease of the spectral dimension as compared to the one of a free propagator. Lowering the momentum scale, the spectral dimension decreases further. The class of propagators which display a maximum at Euclidean momenta, and thus violate positivity, always approaches a spectral dimension of one for large times. We also show that the longest time intervals are not related to the deep infrared but to the momentum scale defined by the position of the maximum.

In this paper, we study the double longitudinal spin asymmetry of dihadron production in semi-inclusive deep inelastic scattering. We calculate an unknown twist-three dihadron fragmentation function ${\tilde{D}}^{\sphericalangle }$ within a spectator model which has been used successfully in describing the dihadron production in both the unpolarized and the single polarized processes. The collinear picture in which the transverse momentum of the final state hadron pair is integrated out has been considered. The $\cos {\varphi }_R$ azimuthal asymmetry arising from the coupling $e_L{H}_1^{\sphericalangle }$ and the coupling $g_1{\tilde{D}}^{\sphericalangle }$ is studied. In general, $e_L(x)$ and its respective contribution vanish model independently and $g_1{\tilde{D}}^{\sphericalangle }$ dominates in this asymmetry. Moreover, we have adopted the same choice as before for the quark mass m fixed to zero GeV, which eliminates the $\mathrm{Re}[F^{s*}{F}^p]$ contribution to the ${\tilde{D}}^{\sphericalangle }$. Using the model results obtained at the low hadronic scale and neglecting the QCD evolution effects, we estimate the $\cos {\varphi }_R$ asymmetry and compare with the COMPASS preliminary data. An estimate for the future electron ion collider is also presented.

We consider the chiral Lagrangian for baryon fields with $J^P={\frac{1}{2}}^{+}$ or $J^P={\frac{3}{2}}^{+}$ quantum numbers as constructed from QCD with up, down and strange quarks. The specific class of counterterms that are of chiral order $Q^3$ and contribute to meson-baryon interactions at the two-body level is constructed. Altogether, we find 24 terms. In order to pave the way for realistic applications, we establish a set of 22 sum rules for the low-energy constants as they are implied by QCD in the large-$N_c$ limit. Given such a constraint, there remain only two independent unknown parameters that need to be determined by either lattice QCD simulations or directly from experimental cross section measurements. At subleading order, we arrive at five parameters.

We revisit the standard representation of the (inverse) Radon transform, which is well known in the mathematical literature. We extend this representation to the case involving the parton distributions. We have found the new additional contribution, which is essentially related to the generalized transverse-momentum dependent parton distribution and double-distribution functions. We discuss the possible relationship of this term with the Sivers function.

The main aim of this paper is a new determination of transverse momentum dependence of unpolarized fragmentation function (TMD FF) in single inclusive hadron production in electron-positron annihilation (SIA) process. Motivated by the need for a reliable and consistent determination of TMD FFs, we use the most recent TMD production cross sections of charged pions (${\pi }^{\pm }$), kaons ($K^{\pm }$), and protons/antiprotons ($p/\overline{p}$) measured in inclusive $e^{+}{e}^{-}$ collisions by Belle Collaboration. These datasets are the first transverse momentum dependence of identified light charged hadron measurements SIA process. In this analysis, referred to as SK19 TMD FFs, the common Gaussian distribution is used for the $P_{hT}$ dependent of the cross section. The uncertainties in the extraction of SK19 TMD FFs are estimated using the standard “Hessian” technique. We study the quality of the TMD FFs determined in this analysis by comparing with the available recent Belle cross sections measurement. For all hadron species, we found a very good agreement between this particular set of experimental data and the corresponding theory calculations over a relatively wide range of transverse momentum $P_{hT}$. As a result of this study, suggestions are identified for possible future research considering the theory improvements and other available experimental observables.

The measured masses and strong decays of ${\mathrm{\Lambda }}_b(6146{)}^0$ and ${\mathrm{\Lambda }}_b(6152{)}^0$ required us to decode them as the $1D$ excited states with $J^P=3/2^{+}$ and $J^P=5/2^{+}$, respectively. Under the suggested assignment, the masses and total decay widths of ${\mathrm{\Lambda }}_b(6146{)}^0$ and ${\mathrm{\Lambda }}_b(6152{)}^0$ can be explained. As a $J^P=3/2^{+}$ state, the ${\mathrm{\Lambda }}_b(6146{)}^0$ should mainly decay into ${\mathrm{\Sigma }}_b(5815)\pi$. However, this theoretical result is in contradiction to the measurement since no significant ${\mathrm{\Lambda }}_b(6146{)}^0\to {\mathrm{\Sigma }}_b(5815{)}^{\pm }{\pi }^{\mp }$ signals were observed by the LHCb. The possible explanations for this difficulty are mentioned. For completeness, we present the prediction of masses and decay widths of other unseen $1D$ bottom baryons in this work. Our results could provide some important clues for the upcoming experiments.

We study the hadronic molecular structure of hidden heavy pentaquarks—new exotic states composed of charmed/bottom baryons and $D(D^{*})/B(B^{*})$ mesons. Based on the observation of three pentaquark candidates $P_c^{+}(4312)$, $P_c^{+}(4440)$, and $P_c^{+}(4457)$ by the LHCb Collaboration we consider the classification of possible flavor partners composed of charmed baryons and $D(D^{*})$ mesons within the hadronic molecular approach. We extend this classification to the bottom sector. Using phenomenological Lagrangians we construct baryon-meson bound states governed by the Weinberg-Salam compositeness condition. As an application we consider strong two-body decays of the new exotic states into a light baryon and $V=J/\psi ,\mathrm{\Upsilon }$ or $P={\eta }_c,{\eta }_b$ mesons. Results are presented in the heavy quark limit.

We estimate here chiral susceptibility at finite temperature within the framework of the Nambu–Jona-Lasinio model (NJL) using the Wigner function approach. We also estimate it in the presence of chiral chemical potential (${\mu }_5$) as well as a nonvanishing magnetic field ($B$). We use a medium separation regularization scheme (MSS) in the precence of magnetic field to calculate the chiral condensate and corresponding susceptibility. It is observed that for a fixed value of chiral chemical potential (${\mu }_5$), transition temperature increases with the magnetic field. While for the fixed value of the magnetic field, transition temperature decreases with chiral chemical potential. For a strong magnetic field, we observe nondegeneracy in susceptibility for up and down type quarks.

We study the nontrivial dispersion relation of mesons resulting from the splitting of the transversal and longitudinal mesonic wave function renormalizations, and its influences on the QCD phase transition, equation of state, and the fluctuations of the baryon number. The calculations are performed in a two-flavor low-energy effective model within the functional renormalization group approach. We find that influences of the splitting mesonic wave function renormalizations on the equilibrium thermodynamical bulk properties are mild. Furthermore, we compare the fixed and running expansion for the effective potential in detail, through which the role of the field-dependent meson and quark wave function renormalizations can be inferred.

Recent observations of ultradwarf galaxy NGC1052-DF2 started an interesting discussion between dark matter hypothesis and modified gravity theories. Reported low-velocity dispersion (less than $10.5\mathrm{km}/\mathrm{s}$ at 90% confidence level) derived from the kinematic data of ten globular clusters in the galaxy points toward an extraordinarily low dynamical mass (approximately $3.4\times {10}^8{M}_{\odot }$), which is of the same order of the luminous mass (approximately $2.0\times {10}^8{M}_{\odot }$) in the galaxy. This has been interpreted as the first evidence of a galaxy “without dark matter.” It has been argued that dark matter is not necessarily coupled to the baryonic mass on the galactic scale and poses a challenge to modified gravity theories. We explore the dynamics of NGC1052-DF2 within the context of four popular alternative theories of gravity [modified Newtonian dynamics (MOND), Weyl conformal gravity, modified gravity (MOG)/scalar-tensor-vector gravity (STVG), and Verlinde’s emergent gravity] and present the analysis of detailed radial variation of the velocity dispersion. We demonstrate that the dispersion data of NGC1052-DF2 are fully consistent with the modified gravity paradigm (as well as with general relativity without dark matter). We reach a similar conclusion for the ultradwarf NGC1052-DF4, which has been claimed to be the second candidate for galaxies without dark matter.

High-accuracy numerical simulations of merging neutron stars play an important role in testing and calibrating the waveform models used by gravitational wave observatories. Obtaining high-accuracy waveforms at a reasonable computational cost, however, remains a significant challenge. One issue is that high-order convergence of the solution requires the use of smooth evolution variables, while many of the equations of state used to model the neutron star matter have discontinuities, typically in the first derivative of the pressure. Spectral formulations of the equation of state have been proposed as a potential solution to this problem. Here, we report on the numerical implementation of spectral equations of state in the spectral Einstein code. We show that, in our code, spectral equations of state allow for high-accuracy simulations at a lower computational cost than commonly used “piecewise polytrope” equations state. We also demonstrate that not all spectral equations of state are equally useful: different choices for the low-density part of the equation of state can significantly impact the cost and accuracy of simulations. As a result, simulations of neutron star mergers present us with a trade-off between the cost of simulations and the physical realism of the chosen equation of state.

The “Shapiro delay” experienced by an astronomical messenger traveling through a gravitational field has been used to place constraints on possible deviations from the equivalence principle. The standard Shapiro delay used to obtain these constraints is not itself an observable in general relativity, but is rather obtained by comparing with a fiducial Euclidean distance. There is not a mapping between the constraints obtained in this manner and alternative theories that exhibit equivalence principle violations. However, even assuming that the comparison with the fiducial Euclidean distance is carried out in a way that is useful for some class of alternative theories, we show that the standard calculation of these constraints cannot be applied on cosmological scales, as is often done. Specifically, we find that the Shapiro delay computed in the standard way (taking the Newtonian potential to vanish at infinity) diverges as one includes many remote sources. We use an infinite homogeneous lattice model to illustrate this divergence, and also show how the divergence can be cured by using Fermi coordinates associated with an observer. With this correction, one finds that the Shapiro delay is no longer monotonic with the number of sources. Thus, one cannot compute a conservative lower bound on the Shapiro delay using a subset of the sources of the gravitational field without further assumptions and/or observational input. As an illustration, we compute the Shapiro delay by applying the Fermi coordinate expression to two catalogs of galaxy clusters, illustrating the dependence of the result on the completeness of the catalogue and the mass estimates.