The Glashow-Iliopoulos-Maiani mechanism is extremely efficient to suppress the flavor-changing neutral current decays of charmed hadrons induced by the $c\to u$ transitions, making such processes particularly sensitive to phenomena beyond the Standard Model. In particular, $c\to u$ decays with a neutrino pair in the final state are theoretically appealing due to the small long-distance contributions. Moreover, in the framework of the Standard Model effective field theory (SMEFT), the $SU(2{)}_L$ invariance allows us to relate the Wilson coefficients in the effective Hamiltonian governing the $c\to u\nu \overline{\nu }$ decays to the coefficients in the $c\to u{\ell }^{+}{\ell }^{-}$ Hamiltonian. We analyze the $B_c\to B^{(*)+}\nu \overline{\nu }$ decays, for which branching fractions of at most $\mathcal{O}({10}^{-16})$ are predicted in the Standard Model including short- and long-distance contributions, so small that they can be considered as null tests. Using SMEFT and the relation to the $c\to u{\ell }^{+}{\ell }^{-}$ processes, we study the largest enhancement achievable in generic new physics scenarios, then we focus on a particular extension of the Standard Model, the 331 model. SMEFT relations and the connection with $c\to u{\ell }^{+}{\ell }^{-}$ imply that $\mathcal{B}(B_c\to B^{(*)+}\nu \overline{\nu })$ could even reach $\mathcal{O}({10}^{-6})$, an extremely large enhancement. A less pronounced effect is found in the 331 model, with $\mathcal{O}({10}^{-11})$ predicted branching fractions. Within the 331 model, correlations exist among the $B_c\to B^{(*)+}\nu \overline{\nu }$ and $K\to \pi \nu \overline{\nu }$, $B\to (X_s,K,K^{*})\nu \overline{\nu }$ channels.

We study the sensitivity of future xenon- and argon-based dark matter and neutrino detection experiments to low-energy atmospheric neutrinos. Not accounting for experimental backgrounds, the primary obstacle for identifying nuclear recoils induced by atmospheric neutrinos in xenon is the tail of the electron recoil distribution due to $pp$ solar neutrinos. We use the NEST code to model the solar and atmospheric neutrino signals in a xenon detector and find that an exposure of 700 tonne-years will produce a $5\sigma$ detection of atmospheric neutrinos. We explore the effect of different detector properties and find that a sufficiently long electron lifetime is essential to the success of such a measurement.

Finite-size scaling is investigated in detail around the critical point in the heavy quark region of nonzero temperature QCD. Numerical simulations are performed with large spatial volumes up to the aspect ratio $N_s/N_t=12$ at a fixed lattice spacing with $N_t=4$. We show that the Binder cumulant and the distribution function of the Polyakov loop follow the finite-size scaling in the $Z(2)$ universality class for large spatial volumes with $N_s/N_t\ge 9$, while, for $N_s/N_t\le 8$, the Binder cumulant becomes inconsistent with the $Z(2)$ scaling. To realize the large-volume simulations in the heavy quark region, we adopt the hopping parameter expansion for the quark determinant: We generate gauge configurations using the leading-order action including the Polyakov loop term for $N_t=4$, and incorporate the next-to-leading order effects in the measurements by the multipoint-reweighting method. We find that the use of the leading-order configurations is crucially effective in suppressing the overlapping problem in the reweighting and thus in reducing the statistical errors.

We present continuum extrapolated results of charmonium and bottomonium correlators in the vector channel at several temperatures below and above $T_c$. The continuum extrapolation jointly performed with the interpolations to have physical values of $J/\psi$ and $\mathrm{\Upsilon }$ masses in the confined phase is based on calculations on several large quenched isotropic lattices using clover-improved Wilson valence fermions carrying different quark masses. The extrapolated lattice correlators are confronted with perturbation theory results incorporating resummed thermal effects around the threshold from potential nonrelativistic QCD (pNRQCD) and vacuum asymptotics above the threshold. An additional transport peak is modeled below the threshold allowing for an estimate of the diffusion coefficients for charm and bottom quarks. We find that charmonium correlators in the vector channel can be well reproduced by perturbative spectral functions above $T_c$ where no resonance peaks for $J/\psi$ are needed at and above $1.1T_c$, while for bottomonium correlators a resonance peak for $\mathrm{\Upsilon }$ is still needed up to $1.5T_c$. By analyzing the transport contribution to the correlators we find that the drag coefficient of a charm quark is larger than that of a bottom quark.

We apply the dynamical diquark model to predict the spectrum of hidden-charm pentaquark states in both unflavored and open-strange sectors. Using only Hamiltonian parameters introduced in the tetraquark $S$- and $P$-wave multiplets, the model naturally produces the level spacing supported by the most recent LHCb results for $P_c$ structures. Furthermore, using model inputs obtained from data of hidden-charm, open-strange tetraquarks ($Z_{cs}$), we predict the spectrum of $P_{cs}$ states, including the recently observed $P_{cs}(4459)$. We find all pentaquark candidates observed to date to belong to the $1P$ multiplet and hence have positive parity.

We explore the implications of the recent radius determination of PSR $\mathrm{J}0740+6620$ by the NICER experiment, combined with the neutron skin measurement by the PREX-II experiment and the associated inference of the slope of symmetry energy, for the structure of hybrid stars with a strong first-order phase transition from nucleonic to quark matter. We combine a covariant density-functional nucleonic equation of state (EOS) with a constant-speed-of-sound EOS for quark matter. We show that the radius and tidal deformability ranges obtained from GW170817 can be reconciled with the implication of the PREX-II experiment if there is a phase transition to quark matter in the low-mass compact star. In the high-mass segment, the EOS needs to be stiff to comply with the large-radius inference for PSR $\mathrm{J}0740+6620$ and $\mathrm{J}0030+0451$ with masses $M\simeq 2M_{\odot }$ and $M\simeq 1.4M_{\odot }$. We show that twin stars are not excluded, but the mass and radius ranges (with $M\ge M_{\odot }$) are restricted to narrow domains $\mathrm{\Delta }{M}_{\mathrm{twin}}\lesssim 0.05M_{\odot }$ and $\mathrm{\Delta }{R}_{\mathrm{twin}}\sim 1.0\mathrm{km}$. We also show that the existence of twin configurations is compatible with the light companion in the GW190814 event being a hybrid star in the case of values of the sound-speed square $s=0.6$ and $s=1/3$.

We study a systematic derivation of four-dimensional $\mathcal{N}=1$ supersymmetric effective theory from a ten-dimensional non-Abelian Dirac-Born-Infeld action compactified on a six-dimensional torus with magnetic fluxes on the D-branes. We find a new type of matter Kähler metric, while gauge kinetic function and superpotential are consistent with previous studies. For the ten-dimensional action, we use a symmetrized trace prescription and focus on the bosonic part up to $\mathcal{O}(F^4)$. In the presence of the supersymmetry, four-dimensional chiral fermions can be obtained via index theorem. The new matter Kähler metric is independent of flavor but depends on the fluxes, 4D dilaton, Kähler moduli, and complex structure moduli and will be always positive definite if an induced Ramond-Ramond charge of the D-branes on which matters are living are positive. We read the superpotential from an F-term scalar quartic interaction derived from the ten-dimensional action and the contribution of the new matter Kähler metric to the scalar potential which we derive turns out to be consistent with the supergravity formulation.

We investigate how entangled inertial Unruh-DeWitt detectors are affected by interaction with a quantum field using a nonperturbative method. Inertial detectors in a ($3+1$)-dimensional Minkowski spacetime with instantaneous switching ($\delta$-switching) experience degradation of their initial entanglement as their coupling strength with a scalar field increases. Somewhat surprisingly, initially separable or weakly entangled detectors can extract mutual information from the vacuum. We also find that entanglement degradation is not reduced if communication via the field is possible; rather this only changes the manner in which entanglement is degraded.

The vacuum $R^2$ model is known to generate a quasi–de Sitter evolution for inflation, using solely the slow-roll assumptions. Using standard reconstruction techniques, we demonstrate that the $f(R)$ gravity which actually realizes the quasi–de Sitter evolution is not simply the $R^2$ model but a deformed $R^2$ model which contains extra terms in addition to the $R^2$ model. We analyze in detail the inflationary dynamics of the deformed $R^2$ model and we demonstrate that the predictions are quite close to the ones of the pure $R^2$ model, regardless the values of the free parameters. Basically the deformed $R^2$ model is also a single parameter inflationary model, exactly like the ordinary $R^2$ model. In contrast to the early-time era, where the deformed $R^2$ model is quite similar to the $R^2$ model, at late times, the phenomenological picture is different. The deformed $R^2$ model describes stronger gravity compared to the ordinary $R^2$ with an effectively smaller effective Planck mass. We propose the addition of an early dark energy term which does not affect at all the inflationary era, but takes over the control of the late-time dynamics at late times. We study in some detail the predicted dark energy era evolution, and we demonstrate that the dark energy corrected deformed $R^2$ model can describe a viable dark energy era, compatible with the Planck constraints on cosmological parameters. Furthermore the model is distinct from the $\mathrm{\Lambda }$ cold dark matter model, but shows a qualitatively similar behavior.

We analyze possibilities to obtain a globally regular stationary generalization for the ultrastatic wormhole with a repulsive scalar field found by Bronnikov and by Ellis in 1973. The extreme simplicity of this static solution suggests that its spinning version could be obtainable analytically and should be globally regular, but no such generalization has been found. We analyze the problem and find that the difficulty originates in the vacuum theory, since the scalar field can be eliminated within the Eris-Gurses procedure. The problem then reduces to constructing the spinning generalization for the vacuum wormhole sourced by a thin ring of negative tension. Solving the vacuum Ernst equations determines the $g_{00}$, $g_{0\phi }$ metric components and hence the AMD mass M and angular momentum J, all of these being specified by the ring source. The scalar field can be included into consideration afterwards, but this only affects $g_{rr}$ and $g_{\vartheta \vartheta }$ without changing the rest. Within this approach, we analyze a number of exact stationary generalizations for the wormhole, but none of them are satisfactory. However, the perturbative expansion around the static vacuum background contains only bounded functions and presumably converges to an exact solution. Including the scalar field screens the singularity at the ring source and renders the geometry regular. This solution describes a globally regular spinning wormhole with two asymptotically flat regions. Even though the source itself is screened and not visible, the memory of it remains in $g_{00}$ and $g_{0\phi }$ and accounts for the $\mathrm{M}\propto {\mathrm{J}}^2$ relation typical for a rotating extended source. Describing stationary spacetimes with an extended source is a complicated problem, which presumably explains the difficulty in finding the solution.

Beginning with a brief review of the regular space-time with asymptotically Minkowski core, we can consider two copies of the space-time connected through a short-throat wormhole whose radius of mouth is equal to or larger than an extremal regular black hole with asymptotically Minkowski core’s event horizon radius. If the wormhole is traversable and smooth, fluxes in these two space-times will interact with and flow into each other. On the cosmological scale, gravity is a candidate for the flux. As the gravitational field changes in one space-time, the behaviors of stars around the wormhole will be affected by the other space-time since we assume that there exists enough exotic matter to keep the wormhole open. The changes in a gravitational field can be quantized through the gauge invariant perturbations. The variances in orbits of stars can be reflected by changes in the kinematic shifts of photon frequencies. Then, we use this to distinguish between the black hole and wormhole generated by the same space-time line element, since a black hole cannot connect two space-times and is unaffected by another space-time.

We study the potential of gravitational wave astronomy to observe the quantum aspects of black holes with tidal heating. According to Bekenstein’s quantization, we find that black hole area discretization can have observable imprints on the gravitational wave signal from an inspiraling binary black hole. We model the absorption lines and compute gravitational wave flux due to tidal heating in such a case. By including the quantization we find the dephasing of the gravitational wave. We discuss the observability of the phenomena in different parameter ranges of the binary. We show that in the inspiral, it leads to vanishing tidal heating for the high spin values. Therefore measuring nonzero tidal heating can rule out area quantization. We also argue that if area quantization is present in nature then our current modeling with reflectivity can probe the Hawking radiation.

The tidal response of a compact object is a key gravitational-wave observable encoding information about its interior. This link is subtle due to the nonlinearities of general relativity. We show that considering a scattering process bypasses challenges with potential ambiguities, as the tidal response is determined by the asymptotic in- and outgoing waves at null infinity. As an application of the general method, we analyze scalar waves scattering off a nonspinning black hole and demonstrate that the low-frequency expansion of the tidal response reproduces known results for the Love number and absorption. In addition, we discuss the definition of the response based on gauge-invariant observables obtained from an effective action description, and clarify the role of analytic continuation for robustly (i) extracting the response and the physical information it contains, and (ii) distinguishing high-order post-Newtonian corrections from finite-size effects in a binary system. Our work is important for interpreting upcoming gravitational-wave data for subatomic physics of ultradense matter in neutron stars, probing black holes and gravity, and looking for beyond-standard-model fields.

The precision measurements of the spectra of cosmic ray nuclei and leptons in recent years have revealed the existence of multiple features, such as the spectral break at $\sim 300\mathrm{GV}$ rigidity seen by PAMELA and AMS-02 and more recently confirmed by DAMPE and CALET, the softening in the spectra of H and He nuclei at $\sim 10$ TV reported by DAMPE, confirming previous hints by NUCLEON and CREAM, a tiny change of slope at $\sim 40\mathrm{GeV}$ in the electron spectrum, revealed by AMS-02, and the large spectral break at $\sim \mathrm{TeV}$ reported by indirect (HESS, MAGIC and VERITAS) and direct (DAMPE, CALET) measurements of the total ($\mathrm{electrons}+\mathrm{positrons}$) lepton spectrum. In all these cases, the possibility has been suggested that these features might reflect the occasional presence of a local cosmic ray source, inducing a noticeable reshaping of the average expected spectra. All these proposals have to face the question of how likely it is for such a source to exist, a question that we address here in a quantitative way. We study the statistical properties of random distribution of sources in space and time, and the effect of the spiral structure of our Galaxy for both the spectra of light nuclei (p and He) and leptons (electrons and positrons) in different energy regions.

We construct the theoretical framework for quasi-two-body $D$ meson decays with the help of pion and kaon electromagnetic form factors and with which we study the contributions of the subprocesses $\rho (770,1450)\to K\overline{K}$ for the three-body $D$ decays within the flavor $SU(3)$ symmetry. Because of the limitations imposed by phase space and strong coupling, the contributions for the kaon pair from the virtual bound state $\rho (770)$ are channel dependent and generally small for the concerned three-body $D$ decays, but some quasi-two-body processes could still be observed in the Dalitz plot analyses for related decays, such as $D^0\to K^{-}\rho (770{)}^{+}\to K^{-}{K}^{+}{K}_S^0$ and $D^{+}\to K_S^0\rho (770{)}^{+}\to K_S^0{K}^{+}{K}_S^0$, they are predicted to have the branching fractions $\mathcal{B}=(0.82\pm 0.04)\times {10}^{-4}$ and $\mathcal{B}=0.47_{-0.03}^{+0.05}\times {10}^{-4}$, which are $(1.86\pm 0.16)\%$ and $(1.84_{-0.16}^{+0.21})\%$, respectively, of the total branching fractions for the corresponding three-body $D$ decays. We find in this work that the normal subprocesses like $\rho (1450{)}^{+}\to {\pi }^{+}{\pi }^0$ or $\rho (1450{)}^{+}\to K^{+}{\overline{K}}^0$, which are bound by the masses of decaying initial states, will provide virtual contributions in some special decays.

We extend the fraternal twin Higgs scenario to include a novel dark matter candidate as well as a mechanism for generating a matter/antimatter asymmetry in both sectors. A spontaneous breaking of twin color results in quark degrees of freedom that are singlets under the residual twin color group. These twin-color-singlet quarks, along with a subdominant component of twin leptons, constitute the asymmetric dark matter. The asymmetry between matter in antimatter in both sectors is cogenerated from the decay of singlet fermions that provide an additional portal between the visible and twin sectors. We discuss the phenomenological aspects of this model, evaluating constraints on the parameter space and highlighting promising discovery channels in future experiments. We briefly discuss how the discovery of signals in multiple experiments may help establish the connection between the mechanisms that address the naturalness, dark matter and matter/antimatter asymmetry puzzles.

In the present work, we investigate several theoretical models of the pion vector form factor and aim at getting the best fit for the two-pion cross sections to reduce the uncertainties of the calculation of two-pion contribution to the muon anomalous magnetic moment. Combined with a polynomial description to the pion vector form factor, we obtain the best fit from the Gounaris-Sakurai (or Kühn-Santamaria) model for the experimental data up to 1 GeV. As a by-product of the fitting results, the branching ratio of $\omega \to \pi \pi$ can be extracted as $\mathrm{Br}(\omega \to \pi \pi )=(1.52\pm 0.06)\%$, which is consistent with the one of the Particle Data Group. With the best fit of the data, we obtain the muon anomalous magnetic moment from two-pion contribution as $a_{\mu }^{\mathrm{HVP},\mathrm{LO}}({\pi }^{+}{\pi }^{-}\le 1\mathrm{GeV})=(497.76\pm 3.15)\times {10}^{-10}$. Our results are consistent with the other works.

We perform a tensor network simulation of the ($1+1$)-dimensional $O(3)$ nonlinear $\sigma$-model with $\theta =\pi$ term. Within the Hamiltonian formulation, this field theory emerges as the finite-temperature partition function of a modified quantum rotor model decorated with magnetic monopoles. Using the monopole harmonics basis, we derive the matrix representation for this modified quantum rotor model, which enables tensor network simulations. We employ our recently developed continuous matrix product operator method [Tang et al., Phys. Rev. Lett. 125, 170604 (2020)] to study the finite-temperature properties of this model and reveal its massless nature. The central charge as a function of the coupling constant is directly extracted in our calculations and compared with field theory predictions.

The present work has been done on the baryons containing one, two, or three bottom quarks. In this article, the ground-state masses of ${\mathrm{\Omega }}_b^{-}$, ${\mathrm{\Xi }}_{bb}^0$, ${\mathrm{\Xi }}_{bb}^{-}$, ${\mathrm{\Omega }}_{bb}^{-}$, and ${\mathrm{\Omega }}_{bbb}^{*-}$ baryons are calculated within the framework of Regge phenomenology. Further, the values of Regge slopes and Regge intercepts for singly, doubly, and triply bottom baryons are estimated in both the ($J$, $M^2$) and ($n$, $M^2$) planes to calculate the excited-state masses of these baryons. Here our attempt is to assign a possible spin parity to recently observed some singly bottom baryons and our results could provide useful information for future experimental searches. Our calculated masses are in agreement with the experimental observations where available and close to other theoretical predictions.