The Leggett inequality is a constraint on the bipartite correlation that admits certain types of nonlocalities. Existing tests mainly focused on the electromagnetic systems where measurement apparatus are assumed to be projective and sharp. However, in nature there are interactions that do not obey the same conservation laws for photon, and the actual measurements may subject to unavoidable uncertainties due to the fundamental physical principles. In this work, we generalize the Leggett inequality to incorporate the measurements that are unsharp and/or biased. It is found that the parity violation in nature provides a spontaneous implementation of an unsharp measurement for the spin of hyperon. A fine structured Leggett inequality for hyperon decays characterized by the asymmetry parameters is obtained and its violation is found which could be observed with the yet obtained data in experiment, like BESIII and Belle.

We propose an experiment to search for axions and axionlike particles in the galactic halo using quantum-enhanced interferometry. This proposal is related to the previously reported ideas [W. DeRocco and A. Hook, Phys. Rev. D 98, 035021 (2018); I. Obata, T. Fujita, and Y. Michimura, Phys. Rev. Lett. 121, 161301 (2018); H. Liu, B. D. Elwood, M. Evans, and J. Thaler, Phys. Rev. D 100, 023548 (2019)] but searches for axions in the mass range from ${10}^{-16}\mathrm{eV}$ up to ${10}^{-8}\mathrm{eV}$ using two coupled optical cavities. We also show how to apply squeezed states of light to enhance the sensitivity of the experiment similar to the gravitational-wave detectors. The proposed experiment has a potential to be further scaled up to a multi-km long detector. We show that such an instrument has a potential to set constrains of the axion-photon coupling coefficient of $\sim {10}^{-18}{\mathrm{GeV}}^{-1}$ for axion masses of ${10}^{-16}\mathrm{eV}$ or detect the signal.

Lepton number violation (LNV) is usually searched for by the LHC collaborations using the same-sign dilepton plus jet signature. In this paper, we discuss multilepton signals of LNV that can arise with experimentally interesting rates in certain loop models of neutrino mass generation. Interestingly, in such models, the observed smallness of the active neutrino masses, together with the high multiplicity of the final states, leads in large parts of the viable parameter space of such models to the prediction of long-lived charged particles, which leave highly ionizing tracks in the detectors. We focus on one particular one-loop neutrino mass model in this class and discuss its LHC phenomenology in some detail.

We explore the Dirac fermionic and complex scalar dark matter in the framework of a hidden $\mathrm{U}(1{)}_{\mathrm{X}}$ gauge theory with kinetic mixing between the $\mathrm{U}(1{)}_{\mathrm{X}}$ and $\mathrm{U}(1{)}_{\mathrm{Y}}$ gauge fields. The $\mathrm{U}(1{)}_{\mathrm{X}}$ gauge symmetry is spontaneously broken due to a hidden Higgs field. The kinetic mixing provides a portal between dark matter and standard model particles. Besides, an additional Higgs portal can be realized in the complex scalar case. Dark matter interactions with nucleons are typically isospin violating, and direct detection constraints can be relieved. Although the kinetic mixing has been stringently constrained by electroweak oblique parameters, we find that there are several available parameter regions predicting an observed relic abundance through the thermal production mechanism. Moreover, these regions have not been totally explored in current direct and indirect detection experiments. Future direct detection experiments and searches for invisible Higgs decays at a Higgs factory could further investigate these regions.

We study the finite temperature localization transition in the spectrum of the overlap Dirac operator. Simulating the quenched approximation of QCD, we calculate the mobility edge, separating localized and delocalized modes in the spectrum. We do this at several temperatures just above the deconfining transition and by extrapolation we determine the temperature where the mobility edge vanishes and localized modes completely disappear from the spectrum. We find that this temperature, where even the lowest Dirac eigenmodes become delocalized, coincides with the critical temperature of the deconfining transition. This result, together with our previously obtained similar findings for staggered fermions shows that quark localization at the deconfining temperature is independent of the fermion discretization, suggesting that deconfinement and localization of the lowest Dirac eigenmodes are closely related phenomena.

We present a formalism to describe two-${\pi }^{+}$ and three-${\pi }^{+}$ dynamics in finite volume, the formalism is based on combination of a variational approach and the Faddeev method. Both pairwise and three-body interactions are included in the presentation. Impacts of finite lattice spacing and the cubic lattice symmetry are also discussed. To illustrate application of the formalism, the pairwise contact interaction that resembles the leading order interaction terms in chiral effective theory is used to analyze recent lattice results.

We construct a tensor network representation of the partition function for the massless Schwinger model on a two-dimensional lattice using staggered fermions. The tensor network representation allows us to include a topological term. Using a particular implementation of the tensor renormalization group we calculate the average plaquette and topological charge density for the theory. For a range of values of the coupling constant for the topological term, $\mathrm{\Theta }$, and the gauge coupling, $\beta$, we compare with results from hybrid Monte Carlo simulations when possible and find good agreement. In order to further understand the role of fermions and topology in this model, we compare calculations of the same observables in a similar model, the Abelian Higgs model.

The rates and spectra of the anomalous $\eta \to {\pi }^{+}{\pi }^{-}\gamma$ and ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}\gamma$ decays are calculated. The approach is based on the effective meson Lagrangian obtained in the Nambu-Jona-Lasinio model with vector and axial-vector mesons by integrating out quark fields. The resulting action is affected by mixing between members of pseudoscalar $J^{PC}=0^{-+}$ and axial-vector $1^{++}$ nonets that violates some low-energy theorems. In this paper we point out that a gauge covariant procedure to diagonalize this mixing allows for consistent description of the $\eta \to {\pi }^{+}{\pi }^{-}\gamma$ and ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}\gamma$ decays.

We treat the $Y(4260)$ resonance as a four-quark state in the framework of the covariant confining quark model. We study two choices of the interpolating current, either the molecular-type current which effectively corresponds to the product of $D$ and ${\overline{D}}_1$ quark currents or tetraquark one. In both cases, we calculate the widths of decays $Y(4260)\to Z_c(3900)+\pi$ and $Y(4260)\to D^{(*)}+{\overline{D}}^{(*)}$. It is found that in both approaches the mode $Y\to Z_c^{+}+{\pi }^{-}$ is enhanced compared with the open-charm modes. However, the absolute value of the $Y\to Z_c^{+}+{\pi }^{-}$ decay width obtained in molecular picture is arguably too large. On the other hand, the value obtained in tetraquark picture is reasonable.

We present predictions for the double parton scattering (DPS) four-jet production cross sections in $pA$ collisions at the LHC. Relying on the experimental capabilities to correlate centrality with impact parameter $B$ of the proton-nucleus collision, we discuss a strategy to extract the double parton scattering contributions in $pA$ collisions, which gives direct access to double parton distribution in the nucleon. We show that the production cross sections via DPS of four jets, out of which two may be light- or heavy-quark jets, are large enough to allow the method to be used already with data accumulated in the 2016 $pA$ run.

The chiral confining Lagrangian, based on chiral theory with quark degrees of freedom, is used to study the spectroscopy of scalar mesons. The formalism does not contain arbitrary fitting parameters, and it takes into account an infinite number of transitions from meson-meson to quark-antiquark states. Starting from known $q\overline{q}$ poles, the transition coefficients ensure the strong shift of the poles for $\pi \pi$ and a much smaller shift for the $K\overline{K}$ systems. The resulting amplitudes $f_{\pi \pi }$ and $f_{K\overline{K}}$ are calculated in terms of $q\overline{q}$ and the free meson Green’s functions. Taking the $\pi \pi /K\overline{K}$ channel coupling into account, one obtains two resonances: a wide resonance $E_1$ in the range 500–700 MeV and narrow $E_2$ near 1 GeV, which can be associated with $f_0(500)$ and $f_0(980)$. A similar analysis, applied to the $I=1$ channel, shows that in this case two very close poles in different sheets appear near $E=980\mathrm{MeV}$, which can be associated with the $a_0(980)$ resonance. The obtained $\pi \pi$ interaction amplitudes, $\mathrm{Re}{f}_{\pi \pi }(E)$ and $\mathrm{Im}{f}_{\pi \pi }(E)$, are compared with the known data.

In this work, we explore the ground state of the QCD system and the relevant collective modes in a parallel electromagnetic (EM) field within the effective three-flavor Nambu–Jona-Lasinio model. From the features of neutral chiral condensates, three critical EM fields are identified in our study: $e{\overline{I}}_2^{c_i}$ ($i=1$, 2, 3). Moreover, competition between QCD and QED anomalies is found: the negativeness of ${\pi }_{\mathrm{d}}^{*}$ and ${\pi }_{\mathrm{s}}^{*}$ is a signal of QCD anomaly dominance for all of the flavors, and the positiveness of ${\pi }_{\mathrm{s}}^{*}$ beyond $e{\overline{I}}_2^{c_1}$ indicates QED anomaly dominance for the strange quark. For the lowest-lying neutral collective modes, the masses of $\mathrm{\Pi }$ and $H$ modes reduce to zero around the critical EM fields and the scalar-pseudoscalar components are exchanged between $\mathrm{\Sigma }$ and $H$ modes, as can be seen in the crossing structure.

The spectroscopic parameters and decay channels of the scalar tetraquark $T_{bb;\overline{u}\overline{s}}^{-}$ (in what follows $T_{b:\overline{s}}^{-}$) are investigated in the framework of the QCD sum rule method. The mass and coupling of the $T_{b:s}^{-}$ are calculated using the two-point sum rules by taking into account quark, gluon and mixed vacuum condensates up to dimension 10. Our result for its mass $m=(10250\pm 270)\mathrm{MeV}$ demonstrates that $T_{b:\overline{s}}^{-}$ is stable against the strong and electromagnetic decays. Therefore to find the width and mean lifetime of the $T_{b:\overline{s}}^{-}$, we explore its dominant weak decays generated by the transition $b\to W^{-}c$. These channels embrace the semileptonic decay $T_{b:\overline{s}}^{-}\to Z_{bc;\overline{u}\overline{s}}^{0}l{\overline{\nu }}_l$ and nonleptonic modes $T_{b:\overline{s}}^{-}\to Z_{bc;\overline{u}\overline{s}}^0{\pi }^{-}(K^{-},D^{-},D_s^{-})$, which at the final state contain the scalar tetraquark $Z_{bc;\overline{u}\overline{s}}^0$. Key quantities to compute partial widths of the weak decays are the form factors $G_1(q^2)$ and $G_2(q^2)$: they determine differential rate $d\mathrm{\Gamma }/d{q}^2$ of the semileptonic and partial widths of the nonleptonic processes, respectively. These form factors are extracted from relevant three-point sum rules at momentum transfers $q^2$ accessible for such analysis. By means of the fit functions $F_{1(2)}(q^2)$ they are extrapolated to cover the whole integration region $m_l^2\le q2\le (m-\tilde{m}{)}^2$, where $\tilde{m}$ is the mass of $Z_{bc;\overline{u}\overline{s}}^0$. Predictions for the full width ${\mathrm{\Gamma }}_{\mathrm{full}}=(15.21\pm 2.59)\times {10}^{-10}\mathrm{MeV}$ and mean lifetime ${4.33}_{-0.63}^{+0.89}\times {10}^{-13}\mathrm{s}$ of the $T_{b:s}^{-}$ are useful for experimental and theoretical investigations of this exotic meson.

Given a two-dimensional conformal field theory with a global symmetry, we propose a method to implement an orbifold construction by taking orbits of the modular group. For the case of cyclic symmetries we find that this approach always seems to be consistent, even in asymmetric orbifold cases where the usual construction does not yield a modular invariant theory; our approach keeps modular invariance manifest but may give a result that is equivalent to the original theory. For the case that the symmetry is a subgroup of a continuous flavor symmetry, we can give explicit constructions of the spectrum, with twisted sectors corresponding to a nonstandard group projection on an enlarged twisted sector Hilbert space.

Warm inflation has been noted previously as a possible way to implement inflationary models compatible with the dS swampland bounds. But often in these discussions, the heat bath dynamics are kept largely unspecified. We point out that the recently introduced minimal warm inflation [K. V. Berghaus, P. W. Graham, and D. E. Kaplan, J. Cosmol. Astropart. Phys. 03 (2020) 034], where an axionic coupling of the inflaton leads to an explicit model for the thermal bath, yields models of inflation that can easily fit cosmological observations while satisfying de Sitter swampland bounds, as well as the swampland distance bound and trans-Planckian censorship.

It is often stated that elimination of tree-level flavor-changing neutral currents in multi-Higgs models requires that all fermions of a given charge to couple to the same Higgs boson. A counterexample was provided by Abe, Sato, and Yagyu in a muon-specific two-Higgs doublet model. In this model, all fermions except the muon couple to one Higgs and the muon couples to the other. We study the phenomenology of the model and show that there is a wide range of parameter space in which the branching ratios of the 125 GeV Higgs are very close to their Standard Model values, with the exception of the branching ratio into muons, which can be substantially suppressed—this is an interesting possibility, since the current value of this branching ratio is $0.5\pm 0.7$ times the Standard Model value. We also study the charged Higgs boson and show that, if it is lighter than 200 GeV, it could have a large branching ratio into $\mu \nu$—even substantially larger than the usual decay into $\tau \nu$. The decays of the heavy neutral scalars are also studied. The model does have a relationship between the branching ratios of the 125 GeV Higgs into $Z$’s, $\tau$’s, and $\mu$’s, which can be tested in future accelerators.

The effects of longitudinal bulk viscous pressure on the heavy quark dynamics have been estimated in a strongly magnetized quark-gluon plasma within the Fokker-Planck approach. The bulk viscous modification to the momentum distribution of bulk degrees of freedom has been obtained in the presence of a magnetic field while incorporating the realistic equation of state of the hot magnetized QCD medium. As the magnetic field breaks the isotropy of the medium, the analysis is done along the directions longitudinal and transverse to the field. The longitudinal bulk viscous contribution is seen to have sizable effects in the heavy quark momentum diffusion in the magnetized medium. The dependence of higher Landau levels and the equation of state on the viscous correction to the heavy quark transport has been explored in the analysis.

One of the solutions of Einstein field equation with cylindrical symmetry is known as black string solution. In this work, the rotating black string solution in de Rham-Gabadadze-Tolley (dRGT) massive gravity is obtained and then called rotating-dRGT black string solution. This solution is a kind of generalized version of rotating anti–de Sitter (AdS)/dS black sting solution containing an additional two more terms characterizing the structure of graviton mass. The horizon structures of the black string are explored. The thermodynamical properties of the black string are investigated. We found that it is possible to obtain the Hawking-Page phase transition depending on the additional structure of the graviton mass, while it is not possible for usual rotating-AdS/dS black string. By analyzing the free energy, we also found that the stable rotating black string is bigger than the nonrotating one.

We present the first results of the search for nonlinear memory from subsolar mass binary black hole (BBH) mergers during the second observing run (O2) of the LIGO and Virgo detectors. The oscillatory chirp signal from the inspiral and merger of low mass BBHs ($M_{\mathrm{Tot}}\le 0.4M_{\odot }$) are at very high frequencies and fall outside the sensitivity band of the current ground-based detectors. However, the nonoscillatory memory signal during the merger saturates toward the lower frequencies and can be detected for those proposed BBHs. We show in this work that the morphology of the memory signal depends minimally upon the source parameters of the binary, thus only the overall amplitude of the signal changes and hence the result can be interpolated for extremely low mass BBH mergers. We did not find any signal which can be interpreted as a memory signal, and we place upper limits on the rate of BBH mergers with $M_{\mathrm{Tot}}\le 0.4M_{\odot }$ for the first time.