We study the radiative leptonic decays $P\to \ell {\nu }_{\ell }{\ell }^{\prime +}{\ell }^{\prime -}$, where $P$ is a pseudoscalar meson and $\ell$ and ${\ell }^{\prime }$ are charged leptons. In such decays the emitted photon is off-shell and, in addition to the “point-like” contribution in which the virtual photon is emitted either from the lepton or the meson treated as a point-like particle, four structure-dependent (SD) form factors contribute to the amplitude. We present a strategy for the extraction of the SD form factors and implement it in an exploratory lattice computation of the decay rates for the four channels of kaon decays ($\ell$, ${\ell }^{\prime }=e$, $\mu$). It is the SD form factors which describe the interaction between the virtual photon and the internal hadronic structure of the decaying meson, and in our procedure we separate the SD and point-like contributions to the amplitudes. We demonstrate that the form factors can be extracted with good precision and, in spite of the unphysical quark masses used in our simulation ($m_{\pi }\simeq 320\mathrm{MeV}$ and $m_K\simeq 530\mathrm{MeV}$), the results for the decay rates are in reasonable semiquantitative agreement with experimental data (for the channels where these exist). Following this preparatory work, the emphasis of our future work will be on obtaining results at physical quark masses and on the control of the systematic uncertainties associated with discretization and finite-volume errors.

This work extends our previous study of isospin symmetric quarkyonic matter to quarkyonic neutron matter which might be relevant to the inner cores of neutron stars. The vector-isovector $\rho$ mesons are introduced to the model mainly to account for isospin density interactions, just like the $\omega$ meson for baryon density interactions. The modified Lagrangian still preserves approximate chiral symmetry which could be significantly broken at lower density. New free parameters are fixed by adopting the experimental constraints on the symmetry energy and its slope at saturation density. Eventually, the pressure, mass-radius relation, and tidal deformability are explored in advance for the quarkyonic neutron stars. While the pressure and tidal deformability are well consistent with experimental and observational restrictions, the mass-radius relation is unable to reproduce the observed two solar mass of PSR $\mathrm{J}0740+6620$.

Recently the LHCb Collaboration reported a new exotic state $T_{cc}^{+}$ which is conjectured to be a molecular state of $D^0{D}^{*+}$ (or $D^{*0}{D}^{+}$) theoretically. Belle Collaboration also searched for tetraquark state $X_{ccss}$ in $D_s{D}_s$ ($D_s^{*}{D}_s^{*}$) final states but no significant signals were observed, which did not rule out the existence of $X_{ccss}$ as a molecular state of $D_s{D}_s$ ($D_s^{*}{D}_s^{*}$). Inspired by these experimental results on double charmed exotic state, in this paper we study whether the molecular bound states of $D_s^{(*)}{D}_s^{(*)}$ and $B_s^{(*)}{B}_s^{(*)}$ can exist with the Bethe-Salpeter (BS) equation approach. We employ heavy meson chiral perturbation theory and one-boson-exchange approximation to calculate the interaction kernels in the BS equations. Our numerical results suggest that two $B_s^{*}$ mesons perhaps form a $0^{+}$ molecular state. Future experimental search for $X_{ccss}$ and $X_{bbss}$ states in other decay channels may shed light on the structure of double charmed exotic state.

In this paper, we present a QCD analysis to extract the fragmentation functions (FFs) of unidentified light charged hadron entitled as SHK22.h from high-energy lepton-lepton annihilation and lepton-hadron scattering datasets. This analysis includes the data from all available single inclusive electron-positron annihilation processes and semi-inclusive deep-inelastic scattering (SIDIS) measurements for the unidentified light charged hadron productions. The SIDIS data that has been measured by the COMPASS experiment could allow the flavor dependence of the FFs to be well constrained. We exploit the analytic derivative of the neural network for fitting of FFs at next-to-leading-order (NLO) accuracy in the perturbative QCD. The Monte Carlo method is implied for all sources of experimental uncertainties and the parton distribution functions as well. Very good agreements are achieved between the SHK22.h FFs set and the most recent QCD fits available in literature, namely, JAM20 and NNFF1.1h. In addition, we discuss the impact arising from the inclusion of SIDIS data on the extracted light-charged hadron FFs. The global QCD resulting at NLO for charged hadron FFs provides valuable insights for applications in present and future high-energy measurement of charged hadron final state processes.

To distinguish $B_c^{*+}(1{{}^{3}S}_1)$ and $B_c^{+}(1{{}^{1}S}_0)$ in the experiments, we propose two methods based on the conservation laws. I. From the angular momentum conservation, a nonzero helicity of $J/\psi$ of $B_c^{(*)+}\to J/\psi {\pi }^{+}$ would be an evidence of $B_c^{*+}$. II. Since $B_c^{+}\to B^{+}\varphi$ is kinematically forbidden, $B_c^{*+}\to B^{+}\varphi$ provides a clean channel to probe $B_c^{*+}$. Particularly, our results show that $B_c^{*+}$ is promising to be observed at LHC via $B_c^{(*)+}\to J/\psi {\pi }^{+}$. On the other hand, we find that $\mathcal{B}(B_c^{*+}\to B^{+}\varphi )=(7.0\pm 3.0)\times {10}^{-9}$, which is also feasible to be measured at the forthcoming experiments at HL-LHC and FCC-hh.

Top quarks, produced in large numbers at the Large Hadron Collider, have a complex detector signature and require special reconstruction techniques. The most common decay mode, the “all-jet” channel, results in a 6-jet final-state which is particularly difficult to reconstruct in $pp$ collisions due to the large number of permutations possible. We present a novel approach to this class of problem, based on neural networks using a generalized attention mechanism, that we call symmetry preserving attention networks (spa-net). We train one such network to identify the decay products of each top quark unambiguously and without combinatorial explosion as an example of the power of this technique. This approach significantly outperforms existing state-of-the-art methods, correctly assigning all jets in 80.7% of 6-jet, 66.8% of 7-jet, and 52.3% of $\ge 8$-jet events respectively.

We study the supersymmetric quantum dynamics of the cosmological models obtained by reducing $D=5$ supergravity to one timelike dimension. This consistent truncation has fourteen bosonic degrees of freedom, while the quantization of the homogeneous gravitino field leads to a $2^{16}$–dimensional fermionic Hilbert space. We construct a consistent quantization of the model in which the wave function of the Universe is a $2^{16}$–component spinor depending on fourteen continuous coordinates, which satisfies eight Dirac-like wave equations (supersymmetry constraints) and one Klein-Gordon-like equation (Hamiltonian constraint). The fermionic part of the quantum Hamiltonian is built from operators that generate a $2^{16}$-dimensional representation of the (infinite-dimensional) maximally compact subalgebra $K(G_2^{++})$ of the rank-4 hyperbolic Kac-Moody algebra $G_2^{++}$. The (quartic-in-fermions) squared-mass term ${\widehat{\mu }}^2$ entering the Klein-Gordon-like equation has several remarkable properties: (i) it commutes with the generators of $K(G_2^{++})$; and (ii) it is a quadratic polynomial in the fermion number $N_F\sim \overline{\mathrm{\Psi }}\mathrm{\Psi }$, and a symplectic fermion bilinear $C_F\sim \mathrm{\Psi }C\mathrm{\Psi }$. Some aspects of the structure of the solutions of our model are discussed, and notably the Kac-Moody meaning of the operators describing the reflection of the wave function on the fermion-dependent potential walls (“quantum fermionic Kac-Moody billiard”).

We consider a system representing self-gravitating balls of dust in an expanding Universe. It is demonstrated that one can prescribe data for such a system at infinity and evolve it backward in time without the development of shocks or singularities. The resulting solution to the Einstein-$\lambda$-dust equations exists for an infinite amount of time in the asymptotic region of the spacetime. Furthermore, we find that if the density is small compared to the cosmological constant, then it is possible to construct Cosmological solutions to the Einstein constraint equations on a standard Cauchy hypersurface representing self-gravitating balls of dust. If, in addition, the density is assumed to be sufficiently small, then this initial data gives rise to a future geodesically complete solution to the Einstein-$\lambda$-dust equations admitting a smooth conformal extension at infinity which can be regarded as a perturbation of de Sitter spacetime. The main technical tools in this analysis are Friedrich’s conformal Einstein field equations for the Einstein-$\lambda$-dust written in terms of a gauge in which the flow lines of the dust are recast as conformal geodesics.

Previous computations of strongly blue tilted axionic isocurvature spectra were computed in the parametric region in which the lightest time-dependent mass is smaller than the Hubble expansion rate during inflation, leading to an overdamped time evolution. Here we present the strongly blue tilted axionic isocurvature spectrum in an underdamped time evolution parametric regime. Somewhat surprisingly, there exist parametric regions with a strong resonant spectral behavior that leads to a rich isocurvature spectral shape. We focus on computing this resonant spectrum analytically in a large parametric region amenable to such computations. Because the spectrum is sensitive to nonperturbative classical field dynamics, a wide variety of analytic techniques are used including a time-space effective potential obtained by integrating out high-frequency fluctuations.

Massive neutrinos suppress the growth of cosmic structure on small, nonlinear scales. It is thus often proposed that using statistics beyond the power spectrum can tighten constraints on the neutrino mass by extracting additional information from these nonlinear scales. We study the information content regarding neutrino mass at the field level, quantifying how much of this information arises from the difference in nonlinear evolution between a cosmology with one fluid [cold dark matter (CDM)] and two fluids ($\mathrm{CDM}+\text{neutrinos}$). We do so by running two $N$-body simulations, one with and one without massive neutrinos, both with the same phases, and matching their linear power spectrum at a given low redshift. This effectively isolates the information encoded in the linear initial conditions from the nonlinear cosmic evolution. We demonstrate that, for $k\lesssim 1h/\mathrm{Mpc}$, and for a single redshift, there is negligible difference in the real-space CDM field between the two simulations. This suggests that all the information regarding neutrino mass is in the linear power spectrum set by the initial conditions. Thus, any probe based on the CDM field alone will have negligible constraining power beyond that which exists at the linear level over the same range of scales. Consequently, any probe based on the halo field will contain little information beyond the linear power. We find similar results for the matter field responsible for weak lensing. We also demonstrate that there may be much information beyond the power spectrum in the 3D matter field; however, this is not observable in modern surveys via dark matter halos or weak lensing. Finally, we show that there is additional information to be found in redshift space.

A pseudoscalar “axionlike” field, $\varphi$, may explain the $3\sigma$ hint of cosmic birefringence observed in the $EB$ power spectrum of the cosmic microwave background polarization data. Is $\varphi$ dark energy or dark matter? A tomographic approach can answer this question. The effective mass of dark energy field responsible for the accelerated expansion of the Universe today must be smaller than $m_{\varphi }\simeq {10}^{-33}\mathrm{eV}$. If $m_{\varphi }\gtrsim {10}^{-32}\mathrm{eV}$, $\varphi$ starts evolving before the epoch of reionization and we should observe different amounts of birefringence from the $EB$ power spectrum at low ($l\lesssim 10$) and high multipoles. Such an observation, which requires a full-sky satellite mission, would rule out $\varphi$ being dark energy. If $m_{\varphi }\gtrsim {10}^{-28}\mathrm{eV}$, $\varphi$ starts oscillating during the epoch of recombination, leaving a distinct signature in the $EB$ power spectrum at high multipoles, which can be measured precisely by ground-based cosmic microwave background observations. Our tomographic approach relies on the shape of the $EB$ power spectrum and is less sensitive to miscalibration of polarization angles.

Dark matter captured by interaction with electrons inside the Sun may annihilate via long-lived mediator to produce observable gamma ray signals. We utilize solar gamma ray flux measurements from the Fermi Large Area Telescope and the High Altitude Water Cherenkov observatory to put bounds on the dark matter electron-scattering cross section. We find that our limits are four to six orders of magnitude stronger than the existing limits for dark matter masses ranging between GeV to PeV scale.

It is known that polar ice is birefringent and that this can have implications for in-ice radio detection of ultrahigh energy neutrinos. Previous investigations of the effects of birefringence on the propagation of radio-frequency signals in ice have found that it can cause time delays between pulses in different polarizations in in-ice neutrino experiments, and can have polarization-dependent effects on power in radar echoes at oblique angles in polar ice. I report, for the first time, on implications for the received power in different polarizations in high energy neutrino experiments, where the source of the emitted signal is in the ice, a biaxial treatment at radio wavelengths is used, and the signals propagate at oblique angles. I describe a model for this and compare with published results from the SPICE in-ice calibration pulser system at South Pole, where unexpectedly high cross-polarization power has been reported for some geometries. The data shows behaviors indicative of the need for a biaxial treatment of birefringence inducing nontrivial rotations of the signal polarization. The behaviors include, but are not limited to, a time delay that would leave an imprint in the power spectrum. I explain why this time delay has the potential to serve as both an in-ice neutrino signature and a measurement of the distance to the interaction. While further work is needed, I expect that proper handling of the effects presented here will increase the science potential of ultrahigh energy neutrino experiments, and may impact the optimal designs of next-generation detectors.

$S$-wave pion-nucleon interactions in the linear sigma model, and in Manohar-Georgi and Gasser-Sainio-Svarc models with finite number of terms in Lagrangians, as well as in a general phenomenological approach are reviewed. Subtleties associated with the current algebra theorems and field redefinitions are discussed. In the first and third models most likely the $s$-wave pion condensation in the isospin-symmetric matter does not occur at least up to high densities, whereas within the second model it may appear already at moderate densities. In the phenomenological approach two parametrizations of the $s$-wave pion-nucleon scattering amplitude and the pion polarization operator used in the literature are considered. The first parametrization employs the off-mass-shell amplitude and allows to fulfil the current algebra theorems. Using it the $s$-wave pion polarization operator in the isospin-symmetric matter is reconstructed within the gas approximation. With this pion polarization operator the $s$-wave pion condensation in the isospin-symmetric matter does not occur at least up to high densities. Second parametrization uses the on-mass-shell pion-nucleon scattering amplitude and does not satisfy the Adler and Weinberg conditions. With such a parametrization most likely the $s$-wave pion condensation in the isospin-symmetric matter may occur already at the nucleon density $n\simeq (1.4-2.5)n_0$, where $n_0$ is the density of the atomic nucleus, that should result in observable effects. Both parametrizations allow us to successfully describe the pion atom data.

Compact U(1) gauge theory in ($3+1$)-dimensions possesses the confining phase, characterized by a linear raise of the potential between particles with opposite electric charges at sufficiently large interparticle separation. The confinement phenomenon is generated by condensation of Abelian monopoles at strong gauge coupling. We study the properties of monopoles and the deconfining order parameter in zero-temperature theory in the presence of ideally conducting parallel metallic boundaries (plates) usually associated with the Casimir effect. Using first-principle numerical simulations in compact U(1) lattice gauge theory, we show that as the distance between the plates diminishes, the vacuum in between the plates experiences a deconfining transition. The phase diagram in the space of the gauge coupling and the interplane distance is obtained.

We study two colors lattice QCD (${\mathrm{QC}}_2\mathrm{D}$) with two flavors of staggered fermions on ${40}^4$ and ${32}^4$ lattices with lattice spacing $a=0.048\mathrm{fm}$ in the wide range of the quark chemical potential ${\mu }_q$. Our focus is on the confinement-deconfinement transition in this theory. Thus we compute the string tension from the Wilson loops and the static quark free energy from the Polyakov loops. We find that the deconfinement transition found earlier in the range ${\mu }_q\approx 800–1000\mathrm{MeV}$ is shifted to higher values. This shift is attributed to decreasing of the lattice spacing used in our simulations in comparison with the earlier study.

We calculate a resummed equation of state with lattice QCD simulations at imaginary chemical potentials. This work presents a generalization of the scheme introduced in [Phys. Rev. Lett. 126, 232001 (2021) to the case of nonzero ${\mu }_S$, focusing on the line of strangeness neutrality. We present results up to ${\mu }_B/T\le 3.5$ on the strangeness neutral line $⟨S⟩=0$ in the temperature range $130\mathrm{MeV}\le T\le 280\mathrm{MeV}$. We also extrapolate the finite baryon density equation of state to small nonzero values of the strangeness-to-baryon ratio $R=⟨S⟩/⟨B⟩$. We perform a continuum extrapolation using lattice simulations of the 4stout-improved staggered action with 8, 10, 12 and 16 time slices.