A surprising consequence of nonlinear flavor evolution is the spontaneous breaking of the initial symmetries of the neutrino gas propagating in a dense astrophysical environment. We explore the flavor conversion physics by taking into account the polar and azimuthal angular distributions of neutrinos and present the very first example of spontaneous symmetry breaking in the context of fast flavor mixing in the nonlinear regime. Intriguingly, we find that fast flavor mixing does not always develop in the proximity of the angular regions with vanishing electron lepton number, as commonly assumed, and large flavor mixing can rapidly spread through all neutrino modes. Such behavior cannot be predicted from the linear regime of the flavor evolution. These results can have major consequences on the physics of compact astrophysical objects.

We use the effective relativistic mean-field (E-RMF) model to study the crustal properties of the neutron star. The unified equations of state (EoS) are constructed using recently developed E-RMF parameter sets, such as FSUGarnet, IOPB-I, and G3. The outer crust composition is determined using the atomic mass evaluation 2020 data [Huang et al. Chin. Phys. C 45, 030002 (2021) along with the available Hartree-Fock-Bogoliubov mass models [Goriely et al. Phys. Rev. C 88, 024308 (2013) for neutron-rich nuclei. The structure of the inner crust is estimated by performing the compressible liquid drop model calculations using the same E-RMF functional as that for the uniform nuclear matter in the liquid core. Various neutron star properties such as mass-radius ($M-R$) relation, the moment of inertia ($I$), the fractional crustal moment of inertia ($I_{\text{crust}}/I$), mass ($M_{\text{crust}}$) and thickness ($l_{\text{crust}}$) of the crust are calculated with three unified EoSs. The crustal properties are found to be sensitive to the density-dependent symmetry energy and slope parameter advocating the importance of the unified treatment of neutron star EoS. The three unified EoSs, IOPB-I-U, FSUGarnet-U, and G3-U, reproduced the observational data obtained with different pulsars, NICER, and glitch activity and are found suitable for further description of the structure of the neutron star.

We used a stationary torsion balance with a beryllium-aluminum composition dipole to search for ultralow-mass bosonic dark matter coupled to baryon minus lepton number. We set 95% confidence limits on the coupling constant $g_{\mathrm{B}-\mathrm{L}}$ for bosons with masses between ${10}^{-18}$ and ${10}^{-16}\mathrm{eV}/c^2$ with the best performance at $m_{\mathrm{DM}}=8\times {10}^{-18}\mathrm{eV}/c^2$ constraining $g_{\mathrm{B}-\mathrm{L}}(\hslash c{)}^{-1/2}<1\times {10}^{-25}$. This provides a complimentary limit to equivalence-principle experiments that search for ultralow-mass bosons as force-mediating particles.

We reconstruct ghost and gluon spectral functions in $2+1$ flavor QCD with Gaussian process regression. This framework allows us to largely suppress spurious oscillations and other common reconstruction artifacts by specifying generic magnitude and length scale parameters in the kernel function. The Euclidean propagator data are taken from lattice simulations with domain wall fermions at the physical point. For the infrared and ultraviolet extensions of the lattice propagators as well as the low-frequency asymptotics of the ghost spectral function, we utilize results from functional computations in Yang-Mills theory and QCD. This further reduces the systematic error significantly. Our numerical results are compared against a direct real-time functional computation of the ghost and an earlier reconstruction of the gluon in Yang-Mills theory. The systematic approach presented in this work offers a promising route toward unveiling real-time properties of QCD.

When one considers a shock wave in the frame where the shock is at rest, on either side one has a steady flow which converges to equilibrium away from the shock. However, hydrodynamics is unable to describe this flow if the asymptotic velocity is higher than the characteristic speed of the theory. We obtain an exact solution for the decay rate to equilibrium for a conformal fluid in kinetic theory under the relaxation time approximation, and compare it to two hydrodynamic schemes, one accounting for the second moments of the distribution function and thus equivalent, in the small deviations from equilibrium limit, to an Israel-Stewart framework, and another accounting for both second and third moments. While still having a finite characteristic speed, the second model is a significant improvement on the first.

We show that an axionlike particle (ALP) naturally implements spontaneous electroweak baryogenesis through a cosmic evolution strongly tied to the electroweak phase transition (EWPT) if it feebly couples to the Higgs field while giving a small contribution to the Higgs boson mass. The observed baryon asymmetry can be generated successfully if the ALP couples strongly enough to the electroweak anomaly. Also interesting is that the ALP contributes to dark matter, and its coupling to a hidden gauge sector makes the relic abundance insensitive to the cosmic history before the EWPT. The ALP explains both the baryon asymmetry and dark matter in a wide range of the couplings owing to the friction induced by the hidden gauge sector. To be compatible with cosmological and astrophysical observations, the ALP should have a mass in the range between about 0.01 and 30 eV, and is further required to be photophobic if its coupling to the electroweak anomaly is strong, constraining the field content and charge assignment of the UV completion.

Searches for neutrino magnetic moments/transitions in low energy neutrino scattering experiments are sensitive to effective couplings, which are an intricate function of the Hamiltonian parameters. We study the parameter space dependence of these couplings in the Majorana (transitions) and Dirac (moments) cases, as well as the impact of the current most stringent experimental upper limits on the fundamental parameters. In the Majorana case we find that for reactor, short-baseline, and solar neutrinos, $CP$ violation can be understood as a measurement of parameter space vectors misalignments. The presence of nonvanishing $CP$ phases opens a blind spot region where—regardless of how large the parameters are—no signal can be observed in either reactor or short-baseline experiments. Identification of these regions requires a combination of different datasets and allows for the determination of those $CP$ phases. We point out that stringent bounds not necessarily imply suppressed Hamiltonian couplings, thus allowing for regions where disparate upper limits can be simultaneously satisfied. In contrast, in the Dirac case stringent experimental upper limits necessarily translate into tight bounds on the fundamental couplings. In terms of parameter space vectors, we provide a straightforward mapping of experimental information into parameter space.

We present a minimal viable gauge-Higgs grand unification scenario in warped space based on a $\text{SU}(6)$ bulk symmetry—unifying the gauge symmetries of the Standard Model and their breaking sector. We show how the issue of light exotic new states is eliminated by appropriately breaking the gauge symmetry on the UV and IR boundaries by either brane scalars or gauge boundary conditions. The Standard Model fermion spectrum is naturally reproduced including Dirac neutrinos and we compute the Higgs potential at one loop, finding easily solutions with a realistic $m_h\sim 125\mathrm{GeV}$. The problem of proton decay is addressed by showing that baryon number is a hidden symmetry of the model. Among the phenomenological consequences, we highlight the presence of a scalar leptoquark and a scalar singlet. The usual $X$, $Y$ gauge bosons from $\text{SU}(5)$ grand unified theories are found at collider accessible masses.

We initiate the study of dark matter (DM) models based on a gapped continuum. Dark matter consists of a mixture of states with a continuous mass distribution, which evolves as the universe expands. We present an effective field theory describing the gapped continuum, outline the structure of the Hilbert space and show how to deal with the thermodynamics of such a system. This formalism enables us to study the cosmological evolution and phenomenology of gapped continuum DM in detail. As a concrete example, we consider a weakly interacting continuum (WIC) model, a gapped continuum counterpart of the familiar weakly interacting massive particle. The DM interacts with the Standard Model via a $Z$ portal. The model successfully reproduces the observed relic density, while direct detection constraints are avoided due to the effect of continuum kinematics. The model has striking observational consequences, including continuous decays of DM states throughout cosmological history, as well as cascade decays of DM states produced at colliders. We also describe how the WIC theory can arise from a local, unitary scalar quantum field theory propagating on a five-dimensional warped background with a soft wall.

We present here two concrete examples of models where a sub-TeV scale breaking of their respective ${\mathcal{T}}_{13}$ and $A_5$ flavor symmetries is able to account for the recently observed discrepancy in the muon anomalous magnetic moment, $(g-2{)}_{\mu }$. Similarities in the flavor structures of the charged-lepton Yukawa matrix and dipole matrix yielding $(g-2{)}_{\mu }$ give rise to strong constraints on low-scale flavor models when bounds from lepton flavor violation (LFV) are imposed. These constraints place stringent limits on the off-diagonal Yukawa structure, suggesting a mostly (quasi)diagonal texture for models with a low flavor breaking scale ${\mathrm{\Lambda }}_f$. We argue that many of the popular flavor models in the literature designed to explain the fermion masses and mixings are not suitable for reproducing the observed discrepancy in $(g-2{)}_{\mu }$, which requires a delicate balance of maintaining a low flavor scale while simultaneously satisfying strong LFV constraints.

There must be Coulomb bound states of a pair of hadrons, which are stable against the strong interaction, with opposite electric charges. Such bound states are hadronic atoms. We study the properties and the production of the ground-state $D^{+}{D}^{-}$ hadronic atom $A_{D^{+}{D}^{-}}$, called dionium, with quantum numbers $J^{PC}=0^{++}$. Using a nonrelativistic effective field theory for the $D^0{\overline{D}}^0\text{−}{D}^{+}{D}^{-}$ coupled-channel system, the mass of the ground-state dionium is predicted to be $(3739.3\pm 0.1)\mathrm{MeV}$, with the binding energy reduced by about 10% compared to the Coulomb binding energy due to the strong interaction. Its width for the decay into the neutral $D^0{\overline{D}}^0$ channel is predicted to be ${1.8}_{-0.6}^{+1.4}\mathrm{keV}$ using lattice inputs for the $D\overline{D}$ strong interaction. The cross section for the inclusive prompt production of the dionium at CMS and LHCb and that for the direct production $p\overline{p}\to A_{D^{+}{D}^{-}}$ at PANDA are estimated at an order-of-magnitude level. In particular, we expect that $\mathcal{O}({10}^3–{10}^5)$ events of the reaction chain $p\overline{p}\to A_{D^{+}{D}^{-}}\to D^0{\overline{D}}^0\to K^{-}{\pi }^{+}{K}^{+}{\pi }^{-}$ can be collected at PANDA, and valuable information on the charmed meson interaction and on understanding charmoniumlike states will be obtained.

A system of gluon fields generated at the earliest phase of relativistic heavy-ion collisions can be described in terms of classical fields. Numerical simulations show that the system is unstable but a character of the instability is not well understood. With the intention to systematically study the problem, we analyze a stability of classical chromomagnetic and chromoelectric fields which are constant and uniform. We consider the Abelian configurations discussed in the past where the fields are due to the single-color potentials linearly depending on coordinates. However, we mostly focus on the non-Abelian configurations where the fields are generated by the multicolor noncommuting constant uniform potentials. We derive a complete spectrum of small fluctuations around the background fields which obey the linearized Yang-Mills equations. The spectra of Abelian and non-Abelian configurations are similar but different and they both include unstable modes. We briefly discuss the relevance of our results for fields which are uniform only in a limited spatial domain.

We discuss the resonant activation phenomenon on a Josephson junction due to the coupling of the Josephson system with axions. We show how such an effect can be exploited for axion detection. A nonmonotonic behavior, with a minimum, of the mean switching time from the superconducting to the resistive state versus the ratio of the axion energy and the Josephson plasma energy is found. We demonstrate how variations in switching times make it possible to detect the presence of the axion field. An experimental protocol for observing axions through their coupling with a Josephson system is proposed.

We report a new measurement of the production cross section for inclusive electrons from open heavy-flavor hadron decays as a function of transverse momentum ($p_{\mathrm{T}}$) at midrapidity ($|y|<0.7$) in $p+p$ collisions at $\sqrt{s}=200\mathrm{GeV}$. The result is presented for $2.5<p_{\mathrm{T}}<10\mathrm{GeV}/c$ with an improved precision above $6\mathrm{GeV}/c$ with respect to the previous measurements, providing more constraints on perturbative QCD calculations. Moreover, this measurement also provides a high-precision reference for measurements of nuclear modification factors for inclusive electrons from open-charm and -bottom hadron decays in heavy-ion collisions.

In the present paper, we show the existence of a fully nonlinear mechanism for the formation of scalarized black holes, which is different from the spontaneous scalarization, and demonstrate its dynamical development. We consider a class of scalar-Gauss-Bonnet gravity theories within which no tachyonic instability can occur. Although the Schwarzschild black holes are linearly stable against scalar perturbations, we show dynamically that for certain choices of the coupling function, they are unstable against nonlinear scalar perturbations. This nonlinear instability leads to the formation of new black holes with scalar hair. The fully nonlinear and self-consistent study of the equilibrium black holes reveals that the spectrum of solutions is more complicated and more than one scalarized branch can exist. We have also considered classes of scalar-Gauss-Bonnet theories where both the standard and the nonlinear scalarization can be present, and they are smoothly connected that completes in an interesting way the picture of black hole scalarization. The fully nonlinear (de)scalarization of a Schwarzschild black hole will always happen with a jump because the stable “scalarized branch” is not continuously connected to the Schwarzschild one that can leave clear observational signatures.

We investigate the nonperturbative structure of Jackiw–Teitelboim gravity at finite cutoff, as given by its proposed formulation in terms of a $T\overline{T}$-deformed Schwarzian quantum mechanics. Our starting point is a careful computation of the disk partition function to all orders in the perturbative expansion in the cutoff parameter. We show that the perturbative series is asymptotic and that it admits a precise completion exploiting the analytical properties of its Borel transform, as prescribed by resurgence theory. The final result is then naturally interpreted in terms of the nonperturbative branch of the $T\overline{T}$-deformed spectrum. The finite-cutoff trumpet partition function is computed by applying the same strategy. In the second part of the paper, we propose an extension of this formalism to arbitrary topologies, using the basic gluing rules of the undeformed case. The Weil–Petersson integrations can be safely performed due to the nonperturbative corrections and give results that are compatible with the flow equation associated with the $T\overline{T}$ deformation. We derive exact expressions for general topologies and show that these are captured by a suitable deformation of the Eynard–Orantin topological recursion. Finally, we study the “slope” and “ramp” regimes of the spectral form factor as functions of the cutoff parameter.

It is generally expected that in a nonsingular cosmological model a cyclic evolution is straightforward to obtain on introduction of a suitable choice of a scalar field with a negative potential or a negative cosmological constant which causes a recollapse at some time in the evolution. We present a counterexample to this conventional wisdom. Working in the realm of loop cosmological models with nonperturbative quantum gravity modifications we show that a modified version of standard loop quantum cosmology based on Thiemann’s regularization of the Hamiltonian constraint while generically nonsingular does not allow a cyclic evolution unless some highly restrictive conditions hold. Irrespective of the energy density of other matter fields, a recollapse and hence a cyclic evolution is only possible if one chooses an almost Planck sized negative potential of the scalar field or a negative cosmological constant. Further, cycles when present do not occur in the classical regime. Surprisingly, a necessary condition for a cyclic evolution, not singularity resolution, turns out to be a violation of the weak energy condition. These results are in a striking contrast to standard loop quantum cosmology where obtaining a recollapse at large volumes and a cyclic evolution is straightforward, and, there is no violation of weak energy condition. On one hand our work shows that some quantum cosmological models even though nonsingular and bouncing are incompatible with a cyclic evolution, and on the other hand demonstrates that differences in various quantization prescriptions in loop cosmology need not be faint and buried in the prebounce regime, but can be striking and profound even in the postbounce regime.

We present a continuous tensor-network construction for the states of quantum fields called continuous projected entangled pair state (cPEPS), which enjoys the same spatial and global symmetries of ground states of relativistic field theories. We explicitly show how such a state can approximate and eventually converge to the free field theory vacuum and suggest a regularization-independent way of estimating the convergence via a universal term in the fidelity per site. We also present a detailed bottom-up construction of the cPEPS as the continuum limit of the conventional lattice projected entangled pair state.