Recently, the vectorlike leptons (VLLs) as a simple extension to the standard model (SM) have attracted widespread attention both in theory and experiments. The present collider searches mainly focus on the studies of their prompt decays, which prefer a relatively large coupling. In this paper, we concentrate on searches for long-lived signatures of the singlet VLLs $F$ or their accompanying scalar particles $\varphi$ both in the hadronic and electronic colliders. The long-lived signatures are naturally induced from small chiral mass mixing between VLLs and SM leptons. Two specific models distinguished by whether the VLLs couple to scalar particles are introduced to realize the aforementioned features. For the long-lived VLLs case, we find that with the kink track method the sensitivities at future HL-LHC with $\sqrt{s}=14\mathrm{TeV}$ can reach the regions for VLL mass $m_F\in [200,1100]\mathrm{GeV}$ and the mass mixing parameter ${\theta }_L\in [{10}^{-10},3\times {10}^{-8}]$. For the long-lived accompanying scalar particle case, by fixing VLLs or scalar mass, or the mass ratio between VLL and the accompanying scalar, we explore the projected sensitivities through the time delay and displaced vertex strategies, which can probe the regions for $m_F\in [200,1200]\mathrm{GeV}$ and coupling $y{\theta }_L\in [{10}^{-11},{10}^{-6}]$. Furthermore, we also explore the long-lived accompanying scalars at the future CEPC provided that the VLLs can couple to the SM first-generation leptons. We find that CEPC has good performances for $m_{\varphi }<120\mathrm{GeV}$ and $m_F<1200\mathrm{GeV}$. These long-lived searches are complementary to previous studies, which opens the door toward the smaller coupling regions.

The framework of three-flavor neutrino oscillation is a well-established phenomenon, but results from the short-baseline experiments, such as the Liquid Scintillator Neutrino Detector (LSND) and MiniBooster Neutrino Experiment (MiniBooNE), hint at the potential existence of an additional light neutrino state characterized by a mass-squared difference of approximately $1{\mathrm{eV}}^2$. The new neutrino state is devoid of all Standard Model (SM) interactions, commonly referred to as a “sterile” state. In addition, a sterile neutrino with a mass-squared difference of ${10}^{-2}{\mathrm{eV}}^2$ has been proposed to improve the tension between the results obtained from the Tokai to Kamioka (T2K) and the NuMI Off-axis ${\nu }_e$ Appearance ($\mathrm{NO}\nu \mathrm{A}$) experiments. Further, the nonobservation of the predicted upturn in the solar neutrino spectra below 8 MeV can be explained by postulating an extra light sterile neutrino state with a mass-squared difference around ${10}^{-5}{\mathrm{eV}}^2$. The hypothesis of an additional light sterile neutrino state introduces four distinct mass spectra depending on the sign of the mass-squared difference. In this paper, we discuss the implications of the above scenarios on the observables that depend on the absolute mass of the neutrinos; namely, the sum of the light neutrino masses ($\mathrm{\Sigma }$) from cosmology, the effective mass of the electron neutrino from beta decay $(m_{\beta })$, and the effective Majorana mass $(m_{\beta \beta })$ from neutrinoless double beta decay. We show that some scenarios can be disfavored by the current constraints of the above variables. The implications for projected sensitivity of Karlsruhe Tritium Neutrino Experiment (KATRIN) and future experiments like Project-8, next Enriched Xenon Observatory (nEXO) are discussed.

We study the potential of the axion, $a$, of Quantum Chromodynamics, in the two-flavor color superconducting phase of cold and dense quark matter. We adopt a Nambu-Jona-Lasinio-like model. Our interaction contains two terms, one preserving and one breaking the $U(1{)}_A$ symmetry: the latter is responsible of the coupling of axions to quarks. We introduce two quark condensates, $h_L$ and $h_R$, describing condensation for left-handed and right-handed quarks respectively; we then study the loci of the minima of the thermodynamic potential, $\mathrm{\Omega }$, in the $(h_L,h_R)$ plane, noticing how the instanton-induced interaction favors condensation in the scalar channel when the $\theta$ angle, $\theta =a/f_a$, vanishes. Increasing $\theta$ we find a phase transition where the scalar condensate rotates into a pseudoscalar one. We present an analytical result for the topological susceptibility, $\chi$, in the superconductive phase, which stands both at zero and at finite temperature. Finally, we compute the axion mass and its self-coupling. In particular, the axion mass $m_a$ is related to the full topological susceptibility via $\chi =m_a^2{f}_a^2$; hence our result for $\chi$ gives an analytical result for $m_a$ in the superconductive phase of high-density Quantum Chromodynamics.

We study the single-inclusive production of prompt photons in electron-proton collisions, $ep\to \gamma X$, for kinematics relevant at the Electron-Ion Collider (EIC). We perform a perturbative calculation of the differential cross section to next-to-leading order in QCD and to lowest order in QED. We consider unpolarized collisions as well as scattering of longitudinally polarized incident electrons and protons. We show that the cross sections are sensitive to the parton distribution functions of photons inside the proton, which we find to generate the dominant contributions in certain kinematical regions at the EIC. We also investigate the effects of photon isolation on the unpolarized and polarized cross sections.

In this paper, we construct the wedge holography for the de Sitter space as a bulk theory. First, we discuss a more general mathematical construction of wedge holography in parallel with wedge holography construction for the AdS bulk, and then we construct the wedge holography in the extended static patch. In the first case, we prove that one can construct wedge holography for the de Sitter bulk for the static patch as well as the global coordinate metric on end-of-the-world branes. Extended static patch wedge holography is constructed by joining the two copies of double holography in DS/dS correspondence. We find that wedge holography with extended static patch metric leads to the emergence of communicating universes. Further, we propose a model which provides the theoretical evidence of communicating multiverses.

The chiral phase boundary of nuclear matter is expected to have a critical point where the rapid crossover of lattice methods at zero chemical potential becomes a first-order phase transition. Phenomenological models based on the AdS/CFT correspondence, known as $\mathrm{AdS}/\mathrm{QCD}$, have succeeded in capturing many features of nuclear matter, with recent progress in producing the expected critical point. We study a model that produces a critical point in the chiral phase diagram by introducing a coupling between the scalar chiral field and the dilaton. We examine the effect of the scalar-dilaton coupling on the critical point. We also study the zero-temperature chiral dynamics, which must allow for spontaneous chiral symmetry breaking in the limit of zero quark mass. We find that when the scalar-dilaton coupling is large enough to ensure correct zero-temperature chiral dynamics, a critical point is present only if the quark mass is greater than 12.8 MeV.

We construct a holographic map that reconstructs massless fields (scalars, Maxwell field, and Fierz-Pauli field) in half-Minkowski spacetime in $d+1$ dimensions terms of smeared primary operators in a large-$N$ factorizable CFT in ${\mathbb{R}}^{d-1,1}$. This map is based on a Weyl (rescaling) transformation from the Poincaré wedge of AdS to the Minkowski half-space and on the Hamilton-Kabat-Lifschytz-Lowe smearing function, which reconstructs local bulk operators in the Poincaré AdS in terms of smeared operators on the conformal boundary of the Poincaré wedge. The massless scalar field is reconstructed up to the level of two-point functions, while the Maxwell field and massless spin-2 fields are reconstructed at the level of the one-point function. We also discuss potential ways the map can be generalized to higher dimensions, and to the full Minkowski space.

The behavior of a chaotic system and its effect on existing quantum correlation has been holographically studied in the presence of nonconformality. Keeping in mind the gauge/gravity duality framework, the nonconformality in the dual field theory has been introduced by considering a Liouville type dilaton potential for the gravitational theory. The resulting black brane solution is associated with a parameter $\eta$ which represents the deviation from conformality. The parameters of chaos, namely, the Lyapunov exponent and butterfly velocity are computed by following the well-known shock wave analysis. The obtained results reveal that the presence of nonconformality leads to suppression of the chaotic nature of a system. Further, for a particular value of the nonconformal parameter $\eta$, the system achieves Lyapunov stability resulting from the vanishing of both the Lyapunov exponent as well as butterfly velocity. Interestingly, this particular value of $\eta$ matches with the previously given upper bound of $\eta$ known as Gubser bound in the literature. The effects of chaos and nonconformality on the existing correlation of a thermofield doublet state have been quantified by holographically computing the thermomutual information in both the presence and absence of the shock wave. Furthermore, the entanglement velocity is also computed, and the effect of nonconformality on it has been observed. Finally, the obtained results for the Lyapunov exponent and the butterfly velocity have also been computed from the pole-skipping analysis. The results from the two approaches agree with each other.

We study the propagation of the quantum field perturbations in the interior of the Schwarzschild black hole. The interior of the black hole is like an anisotropic cosmological background which expands in one extended direction while contracting in azimuthal directions. Solving the quantum mode functions approximately, we calculate the expectation values of physical quantities such as the energy density $⟨\rho ⟩$ and pressure $⟨P⟩$ as measured by an observer in the interior of the black hole. We employ a combination of the $\zeta$ function regularization and dimensional regularization schemes to regularize the UV divergences in the energy momentum tensor associated to these quantum perturbations. By solving the Einstein field equations, we calculate the quantum backreactions induced in the background geometry. We speculate that the effects of quantum fluctuations in the interior of the black hole can be measured by the exterior observer.

The nature of the central singularity of the BTZ geometries—stationary vacuum solutions of $2+1$ gravity with negative cosmological constant $\mathrm{\Lambda }=-{\ell }^{-2}$ and $SO(2)\times \mathbb{R}$ isometry—is discussed. The essential tool for this analysis is the holonomy operator on a closed path (i.e., Wilson loop) around the central singularity. The study considers the holonomies for the Lorentz and ${\mathrm{AdS}}_3$ connections. The analysis is carried out for all values of the mass $M$ and angular momentum $J$, namely, for black holes ($M\ell \ge |J|$) and naked singularities ($M\ell <|J|$). In general, both Lorentz and ${\mathrm{AdS}}_3$ holonomies are nontrivial in the zero-radius limit revealing the presence of deltalike singularity at the origin in the curvature and torsion two-forms. However, in the cases $M\pm J/\ell =-n_{\pm }^2$, with $n_{\pm }\in \mathbb{N}$, recently identified by Giribet et al. [BPS defects in ${\mathrm{AdS}}_3$ supergravity, arXiv:2402.00171] as Bogomol’nyi-Prasad-Sommerfield configurations, the ${\mathrm{AdS}}_3$ holonomy reduces to the identity. Nevertheless, except for the ${\mathrm{AdS}}_3$ spacetime ($M=-1$, $J=0$), all BTZ geometries have a central singularity which is not revealed by local operations.

We consider gravitational waves from a pair of monopoles or black holes that are moving non-relativistically and are connected by a cosmic string. Shortly after the binary’s formation, the connecting string straightens due the direct coupling of its motion to gravitational radiation. Afterwards, the motion of the binary can be well approximated by a nonrelativistic motion of its components that have an additional constant mutual attraction force due to the tension of the straight string that connects them. The orbit shrinks due to the gravitational radiation backreacting on the binary’s components. We find that if the binary’s semimajor axis $a\gg \sqrt{R_1{R}_2/\mu }$, its eccentricity grows on the inspiral’s timescale; here $R_1$ and $R_2$ are the gravitational radii of the binary components, and $\mu$ is the dimensionless tension of the string. When the eccentricity is high, it approaches unity super exponentially. If the binary’s components are a monopole-antimonopole pair, then this leads to the physical collision that would likely destroy the string and annihilate the monopoles when the semimajor axis is still many orders of magnitude greater than the string thickness. If the binary’s components are black holes, then the eccentricity reaches its peak when $a\sim \sqrt{R_1{R}_2/\mu }$, and then decays according to the standard Peters’s formula. The black-hole spins initially become locked to the orbital motion, but then lag behind as the inspiral proceeds. We estimate the string-tension-induced dimensionless spins just prior to the merger and find them to be $\sim {\mu }^{3/8}\ll 1$.

Recently we showed that in Friedman-Lemaître-Robertson-Walker (FLRW) cosmology, the contribution from higher curvature terms in any generic metric gravity theory to the energy-momentum tensor is of the perfect fluid form. Such a geometric perfect fluid can be interpreted as a fluid remaining from the beginning of the Universe where the string theory is thought to be effective. Just a short time after the beginning of the Universe, it is known that the Einstein-Hilbert action is assumed to be modified by adding all possible curvature invariants. We propose that the observed late-time accelerating expansion of the Universe can be solely driven by this geometric fluid. To support our claim, we specifically study the quadratic gravity field equations in $D$ dimensions. We show that the field equations of this theory for the FLRW metric possess a geometric perfect fluid source containing two critical parameters ${\sigma }_1$ and ${\sigma }_2$. To analyze this theory concerning its parameter space $({\sigma }_1,{\sigma }_2)$, we obtain the general second-order nonlinear differential equation governing the late-time dynamics of the deceleration parameter $q$. Hence, using some present-day cosmological data as our initial conditions, our findings for the ${\sigma }_2=0$ case are as follows: (i) To have a positive energy density for the geometric fluid ${\rho }_g$, the parameter ${\sigma }_1$ must be negative for all dimensions up to $D=11$. (ii) For a suitable choice of ${\sigma }_1$, the deceleration parameter experiences signature changes in the past and future, and in the meantime it lies within a negative range, which means that the current observed accelerated expansion phase of the Universe can be driven solely by the curvature of the spacetime. (iii) $q$ experiences a signature change, and as the dimension $D$ of spacetime increases, this signature change happens at earlier and later times, in the past and future, respectively.

The frozen star is a recent proposal for a nonsingular solution of Einstein’s equations that describes an ultracompact object which closely resembles a black hole from an external perspective. The frozen star is also meant to be an alternative, classical description of an earlier proposal, the highly quantum polymer model. Here, we show that the thermodynamic properties of frozen stars closely resemble those of black holes: frozen stars radiate thermally, with a temperature and an entropy that are perturbatively close to those of black holes of the same mass. Their entropy is calculated using the Euclidean-action method of Gibbons and Hawking. We then discuss their dynamical formation by estimating the probability for a collapsing shell of “normal” matter to transition, quantum mechanically, into a frozen star. This calculation followed from a reinterpretation of a transitional region between the Euclidean frozen star and its Schwarzschild exterior as a Euclidean instanton that mediates a phase transition from the Minkowski interior of an incipient Schwarzschild black hole to a microstate of the frozen star interior. It is shown that, up to negligible corrections, the probability of this transition is $e^{-A/4}$, with $A$ being the star’s surface area. Taking into account that the dimension of the phase space is $e^{+A/4}$, we conclude that the total probability for the formation of the frozen star is of order unity. The duration of this transition is estimated, which we then use to argue, relying on an analogy to previous results, about the scaling of the magnitude of the off-diagonal corrections to the number operator for the Hawking-like particles. Such scaling was shown to imply that the corresponding Page curve indeed starts to go down at about the Page time, as required by unitarity.

In the canonical tachyonic resonance preheating scenario, only an order one fraction of energy density in the inflaton is transferred to radiation, due to backreaction effects. One possible way to improve the energy transfer efficiency is to allow for the perturbative decays of the resonantly produced daughter particles, which serve as the “spillway” to drain the direct decay products from inflaton and to reduce the backreaction. In this article, we study two observational consequences of spillway preheating. The first is on the inflationary observables: the scalar spectrum tilt $n_s$ and tensor-to-scalar ratio $r$. The spillway scenario modifies the evolution of the equation of state between the end of inflation and the thermal big bang. As a result, it affects the time elapsed from inflation to the cosmic microwave background, as well as the fits of inflationary models and their corresponding prediction for $n_s$ and $r$. We map out the equation of state by systematically scanning the parameter space of the spillway scenario and show that the most efficient spillway scenario predicts a bluer spectrum, compared to the tachyonic preheating scenario. Another consequence is the production of high-frequency gravitational waves. Comparing the simulation results with those of tachyonic preheating, we find that the existence of spillways leads to sharper-peaked GW spectra with a mildly damped amplitude.

Transient signals arising from instrumental or environmental factors, commonly referred to as glitches, constitute the predominant background of false alarms in gravitational wave searches with ground-based detectors. Therefore, effective data analysis methods for vetoing glitch-induced false alarms are crucial to enhancing the sensitivity of a search. We present a veto method for glitches that impact matched filtering-based searches for binary inspiral signals. The veto uses unphysical sectors in the space of chirp time parameters as well as an unphysical extension including negative chirp times to efficiently segregate glitches from gravitational wave signals in data from a single detector. Inhabited predominantly by glitches but nearly depopulated of genuine gravitational wave signals, these unphysical sectors can be efficiently explored using particle swarm optimization. In a test carried out on data taken from both LIGO detectors spanning multiple observation runs, the veto was able to reject 99.9% of glitches with no loss of signals detected with signal-to-noise ratio $\ge 9.0$ and total detector frame mass $\le 80M_{\odot }$. Our results show that extending a matched filter search to unphysical parts of a signal parameter space promises to be an effective strategy for mitigating glitches.

Models of spontaneous wave function collapse have been postulated to address the measurement problem in quantum mechanics. Their primary function is to convert coherent quantum superpositions into incoherent ones, with the result that macroscopic objects cannot be placed into widely separated superpositions for observably prolonged times. Many of these processes will also lead to loss of coherence in neutrino oscillations, producing observable signatures in the flavor profile of neutrinos at long travel distances. The majority of studies of neutrino oscillation coherence to date have focused on variants of the continuous state localization model, whereby an effective decoherence strength parameter is used to model the rate of coherence loss with an assumed energy dependence. Another class of collapse models that have been proposed posit connections to the configuration of gravitational field accompanying the mass distribution associated with each wave function that is in the superposition. A particularly interesting and prescriptive model is Penrose’s description of gravitational collapse which proposes a decoherence time $\tau$ determined through $E_g\tau \sim \hslash$, where $E_g$ is a calculable function of the Newtonian gravitational potential. Here we explore application of the Penrose collapse model to neutrino oscillations, reinterpreting previous experimental limits on neutrino decoherence in terms of this model. We identify effects associated with both spatial collapse and momentum diffusion, finding that the latter is ruled out in data from the IceCube South Pole Neutrino Observatory so long as the neutrino wave packet width at production is ${\sigma }_{\nu ,x}\le 2\times {10}^{-12}\mathrm{m}$.

The leptonic and semileptonic decays of mesons are investigated within the domain model of quantum chromodynamics (QCD) vacuum and hadronization. The domain model is the mean-field approach based on the statistical ensemble of almost everywhere homogeneous Abelian (anti-)self-dual gluon fields which reproduces main features of low-energy QCD and allows one to deduce a nonlocal effective meson action. Using this meson action, the leptonic decay constants, form factors and branching ratios of semileptonic decays are evaluated simultaneously with masses of mesons. The results are compared to experimental data or other approaches.

The Casimir effect is known to be induced from photon fields confined by a small volume, and also its fermionic counterpart has been predicted in a wide range of quantum systems. Here, we investigate what types of Casimir effects can occur from quark fields in dense and thin quark matter. In particular, in the dual chiral density wave, which is a possible ground state of dense quark matter, we find that the Casimir energy oscillates as a function of the thickness of matter. This oscillating Casimir effect is regarded as an analog of that in Weyl semimetals and is attributed to the Weyl points in the momentum space of quark fields. In addition, we show that an oscillation is also induced from the quark Fermi sea, and the total Casimir energy is composed of multiple oscillations.

We investigate the mass spectra of molecular-type hexaquark states in the dibaryon systems. These systems are composed of the charmed baryons $[{\mathrm{\Sigma }}_c^{(*)},{\mathrm{\Xi }}_c^{(\prime ,*)}]$, doubly charmed baryons $[{\mathrm{\Xi }}_{cc}^{(*)}]$, and hyperons $[{\mathrm{\Sigma }}^{(*)},{\mathrm{\Xi }}^{(*)}]$. We consider all possible combinations of particle-particle and particle-antiparticle pairs, including the S-wave spin multiplets in each combination. We establish the underlying connections among the molecular tetraquarks, pentaquarks, and hexaquarks with the effective quark-level interactions. We find that the existence of molecular states in $D{D}^{*}$, $D{\overline{D}}^{*}$, and ${\mathrm{\Sigma }}_c{\overline{D}}^{(*)}$ systems leads to the emergence of a large number of deuteronlike hexaquarks in the heavy flavor sectors. Currently, there have been several experimental candidates for molecular tetraquarks and pentaquarks. The experimental search for near-threshold hexaquarks will further advance the establishment of the underlying dynamical picture of hadronic molecules and deepen our understanding of the role of spin-flavor symmetry in near-threshold residual strong interactions.

$CP$ violation in baryon decay processes is still undiscovered to date. We present a general analysis of the decay-angular distributions and the corresponding $CP$ asymmetries in cascade decays of the type $\mathbb{H}\to R(\to ab)c$, where $\mathbb{H}$ is a heavy hadron that decays through weak interactions $\mathbb{H}\to Rc$ and the resonance $R$ decays strongly via $R\to ab$. Based on the analysis, we propose to search for $CP$ violation in the decay-angular distributions in the cascade decay processes $\mathbb{B}\to \mathcal{B}M$, with $\mathcal{B}$ or $M$ subsequently decaying through strong interactions, where $\mathbb{B}$ is the mother baryon, $\mathcal{B}$ and $M$ are the daughter baryon and meson, respectively, and $M$ has to be spin nonzero. We also present some typical decay channels in which the search for such kinds of $CP$ asymmetries can be performed.