We propose an extension of the QCD sum rules, termed the resonance sum rules, to access resonance poles in the complex energy plane. By strategically introducing a contour in the complex plane and conformal mapping, the method intends to reach resonance poles on the second Riemann sheet. To validate this approach, we apply resonance sum rules to the square-well potential model, for which the pole locations are known. The analysis demonstrates a successful extraction of the pole positions and residues for both the $S$-wave and $P$-wave resonances. The results are in good agreement with the analytic solutions, with discrepancies within 5% for the pole positions and 20% for the residues. This framework provides a basis for future applications to realistic hadronic resonances, promising new insights into spectral properties of QCD.

The gravitational form factor (GFF) of the kaon is investigated in a bottom-up holographic QCD model, in which the strange quark mass breaks the SU(3) flavor symmetry. The probe energy ($Q^2$) dependence of the kaon GFF is explicitly shown and compared to that of the pion. It is presented that our result shows the $1/Q^2$ behavior in the high energy region, which is consistent with the perturbative QCD prediction. The gravitational radius of the kaon is also calculated, and it is found that the result is quite close to that of the pion but slightly smaller.

The Ricochet experiment aims to measure the coherent elastic neutrino-nucleus scattering process from antineutrinos emitted by a research nuclear reactor operated by the Institut Laue-Langevin (Grenoble, France). This article presents a description of the Ricochet experimental installation and the detector performance achieved during its commissioning with a mini-CryoCube module consisting of three 42-g germanium cryogenic calorimeters. The baseline resolutions and background levels are reported both during reactor-on and reactor-off periods and as noise mitigation techniques were improved. A baseline resolution of 40 eV electron equivalent was achieved for the ionization channel after setup improvements, and the phonon channel resolutions ranged from 50 to 80 eV of total phonon energy. In the energy region from 2 to 7 keV, a nuclear recoil rate of $14(3)\mathrm{events}/(\mathrm{kg}\mathrm{day}\mathrm{keV})$ is measured during the reactor-off period selecting events in coincidence with muon veto signals. This rate is in agreement with the cosmogenic neutron rate calculated from GEANT4 simulations. After the rejection of events in coincidence with signals in the muon veto detectors, a combined 90% confidence level limit on the nuclear recoil background of $<9\mathrm{events}/(\mathrm{kg}\mathrm{day}\mathrm{keV})$ is obtained in that energy region during the reactor-on period, which is compatible with our GEANT4 model calculation corresponding to a total rate of $5\mathrm{events}/(\mathrm{kg}\mathrm{day}\mathrm{keV})$. The sensitivity of this analysis was however found to be limited by a surface event contamination which is currently being addressed by the Ricochet Collaboration with upgraded detectors.

We study a class of UV-complete, strongly coupled, confining three-dimensional field theories, that exhibit a novel stabilization mechanism for the mass of the lightest scalar composite state, relying on the existence of a critical point. The theories admit a holographic dual description in terms of regular backgrounds in 11-dimensional supergravity, which retains its rigorous microscopic interpretation in field theory. The phase diagram includes a line of first-order phase transitions ending at the critical point, where the transition becomes of second order. We calculate the mass spectrum of bound states of the field theory, by considering fluctuations around the background solutions, and find that, near the critical point, a hierarchy of scales develops, such that one state becomes parametrically light. We identify this state as the dilaton, the pseudo-Nambu-Goldstone boson associated with the spontaneous breaking of approximate scale invariance, demonstrating the emergence of this composite state in an ab initio calculation that has a field theory origin. A stabilization mechanism of this type might be exploited to address hierarchy problems in particle and astroparticle physics.

We investigate quantum corrections to scalar quasinormal modes (QNMs) in the near-extremal Reissner-Nordström black hole background with quantum correction in the near-horizon ${\mathrm{AdS}}_2\times {\mathrm{S}}^2$ region. By performing a dimensional reduction, we obtain an effective Jackiw–Teitelboim (JT) gravity theory, whose quantum fluctuations are captured by the Schwarzian action. Using path integral techniques, we derive the quantum-corrected scalar field equation, which modifies the effective potential governing the QNMs. These corrections are extended from the near-horizon region to the full spacetime via a matching procedure. We compute the corrected QNMs using both the third-order Wentzel-Kramers-Brillouin method and the Prony method and find consistent results. Our analysis reveals that quantum corrections can lead to substantial shifts in the real parts of QNM frequencies, particularly for small-mass or near-extremal black holes, while the imaginary parts remain relatively stable. This suggests that quantum gravity effects may leave observable imprints on black hole perturbation spectra, which could be potentially relevant for primordial or microscopic black holes.

We investigate elliptical Wilson loops in $\mathcal{N}=4$ Super Yang–Mills theory at weak and strong coupling for small values of the eccentricity. We obtain analytical results for the vacuum expectation value of the Wilson loop in the form of a series in the eccentricity parameter. At weak coupling, we use perturbation theory in $\mathcal{N}=4$ Super Yang–Mills. At strong coupling, we use the AdS/CFT correspondence, which maps the Wilson loop to the minimal-area world sheet of an open string in anti–de Sitter (AdS) space. We present a novel perturbative method to solve the Nambu–Goto equations allowing us to describe the minimal surface in terms of a coordinate parametrization in Euclidean ${\mathrm{AdS}}_3$. Our results for the regularized area agree with those obtained by Dekel [J. High Energy Phys. 03 (2015) 085.] based on the Polyakov action.

Working in a sector of large charge is a powerful tool to analytically access models that are either strongly coupled or otherwise difficult to solve explicitly. In the context of integrable systems, Volin’s method is exactly such a large-charge approach. In this note, we apply this method to the bi-Yang-Baxter deformed $SU(2)$ principal chiral model. Our main result is an explicit expression for the free energy density as an asymptotic expansion. We moreover determine the leading nonperturbative effects both via analytic methods and a resurgence analysis.

We extend our earlier work on the linearized perturbations of static black holes in Einstein-Maxwell-dilaton (EMD) theories to the case where the black holes are solutions in an enlarged theory including also an axion. We study the perturbations in a three-parameter family of such (Einstein-Maxwell-dilaton-axion) EMDA theories. The systems of equations describing the linearized perturbations can always be separated, but they can only be decoupled when the three parameters are restricted to a one-parameter family of EMDA theories, characterized by a parameter $b$ that determines the coupling of the axion to the ${\epsilon }^{\mu \nu \rho \sigma }{F}_{\mu \nu }{F}_{\rho \sigma }$ term. In the specific case when $b=1$, the theory is related to an $\mathcal{N}=2$ supergravity. In this one case we find that the perturbations in the axial and the polar sectors are related by a remarkable transformation, which generalizes one found by Chandrasekhar for the perturbations of Reissner-Nordström in Einstein-Maxwell theory. This transformation is of a form found in supersymmetric quantum mechanical models. The existence of such mappings between the axial and polar perturbations appears to correlate with those cases where there is an underlying supergravity supporting the solution, even though the black hole backgrounds are nonextremal and therefore not supersymmetric. We prove the mode stability of the static black hole solutions in the supersymmetric EMDA theory. For other values of the parameter $b$ in the EMDA theories that allow decoupling of the modes, we find that one of the radial potentials can be negative outside the horizon if $b$ is sufficiently large, raising the possibility of there being perturbative mode instabilities in such a case.

The $B$-mode of polarization of the CMB is a uniquely powerful probe of gravitational waves produced in the very early Universe, but searches for primordial $B$-mode anisotropies must contend with gravitational lensing, which induces late-time $B$-modes not associated with gravitational waves. These lensing $B$-modes can be removed—i.e., “delensed”—using observations of the $E$-modes and a proxy of the matter fluctuations along the line of sight that caused the deflections. The number density and redshift reach of galaxy surveys such as the upcoming Rubin observatory offer attractive prospects for using them to delens $B$-mode data from CMB experiments such as the Simons Observatory, LiteBIRD or CMB-S4. However, stochasticity and nonlinear galaxy bias may in principle decorrelate the galaxy field from the matter distribution responsible for the lensing effect, thus hindering efforts to delens $B$-modes. In addition, nonlinear gravitational evolution and bias introduce non-Gaussianities in the large-scale structure which further complicate the modeling. We quantify these effects by populating an $N$-body simulation with a magnitude-limited, photometric sample of galaxies similar to Rubin’s gold selection and using them to delens CMB maps lensed by the same matter distribution. We find that pipelines that treat the galaxy overdensity as a Gaussian field will incur negligible bias on the inferred tensor-to-scalar ratio, $r$. Moreover, we show that even in a highly conservative scenario where only the linear bias of the galaxies can be determined, the bias on $r$ arising from this simplification is well within statistical uncertainties for a cosmic-variance limited scenario where Rubin-like galaxies are used for delensing.

We present the spectrum of primordial gravitational wave (GW) expected from the presence of primordial black holes (PBHs) and inflaton in the early Universe. For the first time, to our knowledge, we combine the waves produced by the PBH decay with their density fluctuation counterpart, as well as their effects on the GW produced by the inflaton after (high-frequency modes) and before (low-frequency modes) the end of inflation. We generalize our study for a potential $V(\varphi )\propto {\varphi }^k$ during reheating. We also extend our study, taking into account a possible memory burden effect to see how it can affect the shape of the spectrum.

A very recent and meticulous timing effort suggests that an eccentric millisecond pulsar (eMSP) binary, namely PSR J1618-3921, is likely to be a part of a hierarchical triple (HT) system with a $0.6M_{\odot }$ companion in a $\sim 300\mathrm{yr}$ orbit. We investigate observational implications of the proposed HT scenario for PSR J1618-3921 and our ability to constrain the scenario. We model the MSP-helium white dwarf binary to be a part of bound point-mass HT, while incorporating the effects due to the quadrupolar interactions between the inner and outer binaries, along with dominant order general relativistic contributions to the periastron precession of the inner binary. If the proposed HT system is indeed undergoing Kozai oscillations at the present epoch, the orbital eccentricity ($e$) would be expected to decrease, while the rate of periastron advance ($\dot{\omega }$) would correspondingly increase, for plausible ranges of the HT parameters. Furthermore, the fractional variations in $e$ are anticipated to be at the level of a few parts in ${10}^5$—a magnitude that is substantially larger than the current measurement precision of $e$. We find that, for this eccentric MSP binary, the HT configurations that minimize the temporal evolution of orbital eccentricity and argument of periastron are mutually incompatible. This indicates that the continued high-precision timing of PSR J1618-3921—when analyzed within the framework introduced here—should place stringent limits on the presence and properties of a potential third body in the system.

The study of ultralight dark matter helps to constrain the lower bound of the mass in minimally coupled dark matter models. The granular structure of ultralight dark matter density fields produces metric perturbations which have been identified as a potentially interesting probe of this model. For dark matter masses $m\gtrsim {10}^{-17}\mathrm{eV}$, these perturbations would fluctuate on timescales comparable to observational timescales. In this paper, we estimate the expected time delay these fluctuations would generate in simulated pulsar signals. We simulate arrays of mock pulsars in a fluctuating granular density field. We calculate the expected Shapiro time delay, gravitational redshift, and Doppler shift and compare analytical estimates with the results of simulations. Finally, we provide a comparison with existing pulsar observation sensitivities.

We study the cooling of isolated dark-matter-admixed neutron stars, employing a realistic nuclear equation of state and realistic nuclear pairing gaps, together with fermionic dark matter of variable particle mass and dark-matter fraction. The related parameter space is scanned for the stellar structural and cooling properties. We find that a consistent description of all current cooling data requires fast direct Urca cooling and reasonable proton 1S0 gaps. Dark matter affects the cooling properties by a modification of the nuclear density profiles, but also changes stellar radius and maximum mass. Possible signals of a large dark matter content could be a very massive but slow-cooling star or a very light but fast-cooling star.

Pulsar timing arrays (PTAs) have recently made significant strides in detecting a gravitational-wave background (GWB). The Hellings–Downs (HD) correlation, traditionally considered the hallmark of a GWB, has been observed with compelling evidence in a common-spectrum signal. However, the HD curve is derived under the assumption of discrete and noninterfering sources—an assumption unlikely to hold in realistic scenarios involving interference among numerous GW sources, such as supermassive black hole binaries. In this work, we demonstrate how such interference generates measurable, frequency-dependent spatial correlations that deviate from the HD curve. The spatial correlations for interfering sources (referred to as ISC) still exhibit contributions in the quadrupole and higher multipoles, resembling the HD correlation and encoding the characteristic nature of gravitational-wave radiation. We apply the ISC framework to search for a GWB in the NANOGrav 15-yr dataset. Although current sensitivity limits the performance of the multiparameter ISC model in direct model comparison, a marked improvement in statistical significance is achieved when the parameters are fixed to their best-fit values. While this improvement may be overly optimistic at present, it highlights the potential for significantly enhancing GWB detection by accounting for interference effects, particularly as PTA sensitivity improves in future observations.

Recent detection of very-high-energy neutrino emission from Seyfert type active galactic nuclei (AGN) provides a new insight into the physics of the AGN central engines. We notice that if high-energy protons responsible for neutrino emission are accelerated close to the surface of the accretion disk, the neutrino flux may have no unambiguously identifiable electromagnetic counterpart. This is because the electromagnetic power released in interactions of high-energy protons would only contribute to the heating of the disk surface and corona above the disk, rather than escape from the source. Given that the heat deposited in the corona is released in the hard x-ray range we notice that there still might be an “indirect” electromagnetic counterpart of the neutrino signal: the hard x-ray flux variability may be strongly or weakly correlated with the neutrino flux variations, depending on the importance of the high-energy proton heating in the disk/corona heat balance. If heating by high-energy protons provides a sizable contribution to the overall corona heating rate, the overall flux of diffuse GeV neutrino background from Seyfert galaxies may be comparable to the x-ray background flux and the high-energy tail of this background can provide a sizable contribution to the astrophysical neutrino flux in the TeV band.

In the work, we study the production of dark baryon $\psi$ with the bottom-baryon decays ${\mathrm{\Lambda }}_b\to P\psi$ under the perturbative quantum chromodynamics (QCD) approach. For the type-I/II models in B-mesogenesis scenarios, we calculate the form factors for bottom-baryon decays into meson. Using these results, we obtain branching ratios for ${\mathrm{\Lambda }}_b\to P\psi$ decays. The PQCD approach calculations show these branching ratios reach $\mathcal{O}({10}^{-5})$ in both models, with $\mathcal{B}({\mathrm{\Lambda }}_b\to K\psi )$ specifically reaching $\mathcal{O}({10}^{-4})$ in type-II. These accessible magnitudes make the predictions testable at the LHCb and B-factories with improved precision.

We investigate the process of electron-positron pair creation from the vacuum in the presence of a static and spatially inhomogeneous electric field. In a common visualization of the Schwinger process, virtual particles are accelerated along the direction of the field’s force, transitioning into real particles. Within a nonrelativistic, quantum mechanical framework, a particle cannot gain kinetic energy perpendicular to the external field. However, in the Schwinger mechanism, particles with significant transverse (perpendicular) momenta are predicted. In this study, we analyze the properties of particles with transverse momentum and observe that particles moving rapidly along the field direction (longitudinally) tend to acquire larger transverse momenta. Conversely, positrons with slower longitudinal velocities can only gain small amounts of transverse momentum during their creation.

Total and energy-angle differential probabilities of positrons created in slow collisions of two identical nuclei are calculated within a relativistic two-center approach. The time-dependent Dirac equation is solved in the rotating frame using the generalized pseudospectral method in modified prolate spheroidal coordinates. The magnetic interaction induced by the motion of the nuclei is included in the Hamiltonian. The rotational coupling term is also taken into account. Angle-integrated and angle-resolved energy spectra of the emitted positrons are calculated by projecting the propagated wave function onto positive-energy plane-wave states. Our results show that the magnetic interaction leads to a slight increase in the critical internuclear distance and enhances the total positron yield by up to several percentages. However, it does not qualitatively alter the energy or angular distributions of emitted positrons. The angular distributions remain nearly isotropic. Most important, the characteristic signatures of the supercritical regime identified in the previous calculations neglecting the magnetic interaction are preserved and can help to detect spontaneous vacuum decay.

The Belle II collaboration recently reported a $2.7\sigma$ excess in the rare decay $B^{\pm }\to K^{\pm }\nu \overline{\nu }$, potentially signaling new physics. We propose an axionlike particle (ALP)-portal dark matter (DM) framework to explain this anomaly while satisfying the observed DM relic abundance. By invoking a resonant annihilation mechanism ($m_a\sim 2m_{\chi }$), we demonstrate that the ALP-mediated interactions between the Standard Model and DM sectors simultaneously account for the $B^{\pm }\to K^{\pm }\nu \overline{\nu }$ anomaly and thermal freeze-out dynamics. Two distinct scenarios—long-lived ALPs decaying outside detectors (displaced diphotons) and ALPs decaying invisibly to DM pairs (missing energy)—are examined. While the displaced diphotons scenario is excluded by kaon decay bounds ($K^{\pm }\to {\pi }^{\pm }+\mathrm{inv}$.), the invisible decay channel remains unconstrained and aligns with Belle II’s missing energy signature. Using the coupled Boltzmann equation formalism, we rigorously incorporate early kinetic decoupling effects, revealing deviations up to a factor of 20 from traditional relic density predictions in resonance regions. For the missing energy scenario, the viable parameter space features ALP–Standard Model (SM) and ALP-DM couplings: $g_{aWW}(g_{a\gamma \gamma })\in (7.13\times {10}^{-5}–9.60\times {10}^{-5}){\mathrm{GeV}}^{-1}$ (from $B^{\pm }\to K^{\pm }a$) and $g_{a\chi \chi }\in (7.12\times {10}^{-5}–7.73\times {10}^{-3}){\mathrm{GeV}}^{-1}$ (for resonant annihilation), accommodating ALP masses $m_a\in (0.6,4.8)\mathrm{GeV}$. Therefore, this work establishes the ALP portal as a viable bridge between the $B^{\pm }\to K^{\pm }\nu \overline{\nu }$ anomaly and thermal DM production, emphasizing precision calculations of thermal decoupling in resonance regimes.