We study the semileptonic decay of the doubly heavy baryon ${\mathrm{\Xi }}_{cc}^{++}$ into the singly heavy baryon ${\mathrm{\Xi }}_c^{+}$ within the three-point QCD sum rule approach in two possible lepton channels. Our analysis includes perturbative as well as nonperturbative condensation contributions up to dimension 5. We evaluate the form factors of this semileptonic decay entering the amplitude described by the vector and axial vector transition currents. The fit functions of the form factors with respect to the transferred momentum squared are utilized to predict the decay widths and branching ratios of the ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Xi }}_c^{+}\overline{\ell }{\nu }_{\ell }$ channels. We compare our findings with other predictions in the literature. Our outcomes can be useful for experimental groups in their search for the weak decays of doubly heavy baryons and may be checked via future experiments such as LHCb.

The precise determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements is very important because it could be a clue to new physics beyond Standard Model. This is particular true of $V_{ud}$ because it is the main contribution to the unitary condition of the CKM matrix elements. The level of accuracy for the test of the unitarity involving the element $V_{ud}$ is now of the order of ${10}^{-4}$. Because the precise data for $V_{ud}$ is usually extracted from superallowed nuclear $\beta$ decay, it is quite significant to investigate the breaking of SU(3) flavor symmetry on the weak vector coupling constant in nuclear matter. The purpose of this paper is to investigate how the isoscalar scalar ($\sigma$) and the isovector scalar ($\delta$ or $a_0$) mean-fields affect the weak vector and axial-vector coupling constants for semileptonic baryon (neutron, $\mathrm{\Lambda }$, or ${\mathrm{\Xi }}^{-}$) decay in asymmetric nuclear matter. To do so, we use the quark-meson coupling (QMC) model, where nuclear matter consists of nucleons including quark degrees of freedom bound by the self-consistent exchange of scalar and vector mesons. We pay careful attention to the center of mass correction to the quark currents in matter. We then find that, for neutron $\beta$ decay in asymmetric nuclear matter, the defect of the vector coupling constant due to the $\delta$ field can be of the order of ${10}^{-4}$ at the nuclear saturation density, which is the same amount as the level of the current uncertainty in the measurements. It is also interesting that, in neutron-rich matter, there exists a certain low density at which isospin symmetry is restored, that is, the $u-d$ quark mass difference vanishes. Furthermore, we qualitatively investigate the variation of axial-vector coupling constants in matter, to which the $\sigma$ field mainly contributes. We conclude that the effect of the isoscalar scalar and the isovector scalar fields should be considered in baryon semileptonic decays in nuclei.

A search for heavy right-handed Majorana neutrinos is performed with the ATLAS detector at the CERN Large Hadron Collider, using the $140{\mathrm{fb}}^{-1}$ of proton–proton collision data at $\sqrt{s}=13\mathrm{TeV}$ collected during Run 2. This search targets $t\overline{t}$ production, in which both top quarks decay into a bottom quark and a $W$ boson, where one of the $W$ bosons decays hadronically and the other decays into an electron or muon and a heavy neutral lepton. The heavy neutral lepton is identified through a decay into an electron or muon and another $W$ boson, resulting in a pair of same-charge same-flavor leptons in the final state. This paper presents the first search for heavy neutral leptons in the mass range of 15–75 GeV using $t\overline{t}$ events. No significant excess is observed over the background expectation, and upper limits are placed on the signal cross sections. Assuming a benchmark scenario of the phenomenological type-I seesaw model, these cross section limits are then translated into upper limits on the mixing parameters of the heavy Majorana neutrino with Standard Model neutrinos.

We describe a measurement of charge-parity ($CP$) violation asymmetries in $B^0\to {\eta }^{\prime }{K}_{\mathrm{S}}^0$ decays using Belle II data. We consider ${\eta }^{\prime }\to \eta (\to \gamma \gamma ){\pi }^{+}{\pi }^{-}$ and ${\eta }^{\prime }\to \rho (\to {\pi }^{+}{\pi }^{-})\gamma$ decays. The data were collected at the SuperKEKB asymmetric-energy $e^{+}{e}^{-}$ collider between the years 2019 and 2022, and contain $(387\pm 6)\times {10}^6$ bottom-antibottom meson pairs. We reconstruct $829\pm 35$ signal decays and extract the $CP$ violating parameters from a fit to the distribution of the proper-decay-time difference between the two $B$ mesons. The measured direct and mixing-induced $CP$ asymmetries are $C_{{\eta }^{\prime }{K}_{\mathrm{S}}^0}=-0.19\pm 0.08\pm 0.03$ and $S_{{\eta }^{\prime }{K}_{\mathrm{S}}^0}=+0.67\pm 0.10\pm 0.03$, respectively, where the first uncertainties are statistical and the second are systematic. These results are in agreement with current world averages and standard model predictions.

By analyzing $e^{+}{e}^{-}$ annihilation data corresponding to an integrated luminosity of $7.93{\mathrm{fb}}^{-1}$, collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, we search for the semileptonic decays $D^0\to K^{-}\eta e^{+}{\nu }_e$, $D^{+}\to K_S^0\eta e^{+}{\nu }_e$ and $D^{+}\to \eta \eta e^{+}{\nu }_e$ for the first time. We present evidence for $D^0\to K^{-}\eta e^{+}{\nu }_e$ with a significance of $3.3\sigma$. The branching fraction of $D^0\to K^{-}\eta e^{+}{\nu }_e$ is measured to be $(0.84_{-0.34}^{+0.29}\pm 0.22)\times {10}^{-4}$. No significant signals are observed for the decays $D^{+}\to K_S^0\eta e^{+}{\nu }_e$ and $D^{+}\to \eta \eta e^{+}{\nu }_e$ and we set the upper limits on their branching fractions.

I derive constraints on the Dirac spectrum in the chirally symmetric phase of a gauge theory with two massless fermion flavors. Using only general properties of correlation functions of scalar and pseudoscalar bilinears, I prove that in the chiral limit of vanishing fermion mass $m$ the corresponding susceptibilities and all their derivatives with respect to $m^2$ must be finite. I then use the resulting spectral constraints to show that effective breaking of the anomalous $\mathrm{U}(1{)}_A$ symmetry is allowed in the $\mathrm{SU}(2{)}_A$ symmetric phase in the chiral limit, and leads to distinctive spectral features: (i) the spectral density must develop a singular $O(m^4)/\lambda$ peak as $m\to 0$, (ii) the two-point eigenvalue correlator of near-zero modes must be singular, and (iii) near-zero modes cannot be localized. Moreover, in the symmetric phase the topological charge distribution must be indistinguishable from that of an ideal gas of instantons and anti-instantons of vanishing density, to leading order in $m$.

It is shown how to nonperturbatively define a random matrix model that captures key physics of $\mathcal{N}=2$ Jackiw-Teitelboim supergravity, going well beyond the perturbative topological expansion defined recently by Turiaci and Witten. A decomposition into an infinite family of certain multicritical models is derived, leading to the definition of a nonlinear ordinary differential equation from which the physics may be computed. Bogomol’nyi-Prasad-Sommerfield (BPS) states are naturally described by the model. The nonperturbative completions of the spectral densities for non-BPS multiplets are readily extracted.

Numerical computations and methods have become increasingly crucial in the study of spin foam models across various regimes. This paper adds to this field by introducing new algorithms based on tensor network methods for computing amplitudes, focusing on topological SU(2) BF and Lorentzian Engle-Pereira-Rovelli-Livine spin foam models. By reorganizing the sums and tensors involved, vertex amplitudes are recast as a sequence of matrix contractions. This reorganization significantly reduces computational complexity and memory usage, allowing for scalable and efficient computations of the amplitudes for larger representation labels on standard consumer hardware—previously infeasible due to the computational demands of high-valent tensors. We apply these tensor network algorithms to analyze the characteristics of various vertex configurations, including Regge and vector geometries for the SU(2) BF theory, demonstrating consistent scaling behavior and differing oscillation patterns. Our benchmarks reveal substantial improvements in computational time and memory allocations, especially for large representation labels. Additionally, these tensor network methods are applicable to generic 2-complexes with multiple vertices, where we introduce partial-coherent vertex amplitudes to streamline the computations. The implementation of these algorithms is available on github for further exploration and use.

Photons impinging on strong electromagnetic fields can change both momentum and helicity state, due to quantum vacuum polarization. We investigate these effects in the collision of photons with impulsive PP-waves, which describe e.g. the fields of ultraboosted charge distributions. We connect our results to vacuum birefringence and quantum reflection in both QED and SUSY QED. We also compare with helicity flip in plane wave backgrounds, exploring how and when known tree-level relations, relating amplitudes in PP-waves and in plane waves, extend to one-loop corrections.

We study the dynamical Casimir effect for a real scalar field $\phi$ in $d+1$ dimensions, in the presence of a mirror that imposes Dirichlet boundary conditions and undergoes time-dependent motion or deformation. Using a perturbative approach, we expand in powers of the deviation of the mirror’s surface $\mathrm{\Sigma }$ from a hyperplane, up to fourth order. General expressions for the probability of pair creation induced by motion are derived, and we analyze the impact of space-time dimensionality as well as of the nonlinear effects introduced by the fourth-order terms.

In a remarkable study by Gleiser and Jiang [Stability bounds on compact astrophysical objects from information-entropic measure, Phys. Rev. D 92, 044046 (2015)], the authors demonstrated that the stability regions of neutron stars, within the framework of the simple Fermi gas model, and self-gravitating configurations of complex scalar field (boson stars) with various self-couplings, obtained through traditional perturbation methods, correlate with critical points of the configurational entropy with an accuracy of a few percent. Recently, Koliogiannis et al. [Configurational entropy as a probe of the stability condition of compact objects, Phys. Rev. D 107, 044069 (2023)] found that, while the minimization of the configurational entropy generally anticipates qualitatively the stability point for neutron stars and quark stars, this approach lacks universal validity. In this work, we aim to further elucidate this issue by seeking to reconcile these seemingly contradictory findings. Specifically, we calculate the configurational entropy of bosonic and fermionic systems, described by interacting Fermi and boson gases, respectively, which form compact objects stabilized by gravity. We investigate whether the minimization of configurational entropy coincides with the stability point of the corresponding compact objects. Our results indicate a strong correlation between the stability points predicted by configurational entropy and those obtained through traditional methods, with the accuracy of this correlation showing a slight dependence on the interaction strength. Consequently, the stability of compact objects, composed of components obeying Fermi or boson statistics, can alternatively be assessed using the concept of configurational entropy.

Numerical relativity (NR) simulations of binary black holes provide precise waveforms, but are typically too computationally expensive to produce waveforms with enough orbits to cover the whole frequency band of gravitational-wave observatories. Accordingly, it is important to be able to hybridize NR waveforms with analytic, post-Newtonian (PN) waveforms, which are accurate during the early inspiral phase. We show that to build such hybrids, it is crucial to both fix the Bondi-Metzner-Sachs (BMS) frame of the NR waveforms to match that of PN theory, and optimize over the PN parameters to mitigate the error caused by the discrepancy between NR and PN parameters. We test such a hybridization procedure including all spin-weighted spherical harmonic modes with $|m|\le \ell$ for $\ell \le 8$, using 29 NR waveforms with mass ratios $q\le 10$ and spin magnitudes $|{\chi }_1|,|{\chi }_2|\le 0.8$. We find that for spin-aligned systems, the PN and NR waveforms agree very well. The difference is limited by the small nonzero orbital eccentricity of the NR waveforms, or equivalently by the lack of eccentric terms in the PN waveforms. To maintain full accuracy of the simulations, the matching window for spin-aligned systems should be at least 5 orbits long and end at least 15 orbits before merger. For precessing systems, the errors are larger than for spin-aligned cases. The errors are likely limited by the absence of precession-related spin-spin PN terms. Using ${10}^{5}M$ long NR waveforms, we find that there is no optimal choice of the matching window within this time span, because the hybridization result for precessing cases is always better if using earlier or longer matching windows. We provide the mean orbital frequency of the smallest acceptable matching window as a function of the target error between the PN and NR waveforms and the black hole spins.

We conduct numerical simulations on the scalarization of charged black holes, uncovering the crucial role of the nonlinear terms ($\lambda {\varphi }^4)/2+({\mu }^2{\varphi }^2)/2$ in the critical phenomena of black hole dynamical scalarization. Our findings indicate that the critical parameters exhibit a linear dependence on $\lambda$ and ${\mu }^2$. We particularly emphasize the temporal patterns of the critical solution and the power-law behavior of black hole mass in critical phenomena. Importantly, we observe that in the relationship between the time spent on the critical solution and the initial parameters, both subcritical and supercritical cases follow the same pattern, differing only in the constant within the linear relationship. In all cases, the black hole mass shows a power-law behavior, although with different exponents.

The quantum Oppenheimer-Snyder model for higher-dimensional spacetimes is studied. The higher-dimensional quantum-corrected Schwarzschild black hole is obtained by the junction condition. It turns out that quantum bounces always occur in the collapse, thus the classical gravitational collapse singularities are avoided. The scalar perturbations upon the quantum-corrected black holes are also studied. It turns out that the quantum corrections enhance the oscillation frequency in lower dimensions and decrease it in higher dimensions. Moreover, the thermodynamic laws of the quantum-corrected black holes imply that the Hawking temperature of quantum-corrected black hole decreases as the mass decreases in contrast to the classical situation. The behavior of heat capacity indicates that quantum corrections introduce an extra phase transition of the black holes.

Neutron star binaries and their associated gravitational wave signal facilitate precision tests of general relativity. Any deviation of the detected gravitational waveform from general relativity would therefore be a smoking gun signature of new physics, in the form of additional forces, dark matter particles, or extra gravitational degrees of freedom. To be able to probe new theories, precise knowledge of the expected waveform is required. In our work, we consider a generic setup by augmenting general relativity with an additional, massive scalar field. We then compute the inspiral dynamics of a binary system, for circular orbits, by employing an effective field theoretical approach, while giving a detailed introduction to the computational framework. Finally, we derive the modified taylorf2 phase of the gravitational wave signal at next-to-leading order in the post-Newtonian expansion, and leading order in the parameters of the scalar sector, such as the scalar charge. As a consequence of our model-agnostic approach, our results are readily adaptable to a plethora of new physics scenarios, including modified gravity theories and scalar dark matter models.

We propose hexagonal ice (${\mathrm{H}}_2\mathrm{O}$) as a new target for light dark matter (DM) direct detection. Ice, a polar material, is suitable for single phonon detection through DM scattering for which we consider light dark photon and light scalar mediator models. We report a rate sensitivity down to a DM mass of $\sim \mathrm{keV}$, constituting a broader mass range than other promising candidates. We find better sensitivity for near-term experimental thresholds from the presence of high-frequency phonons. These advantages, and ice’s availability, make it highly promising for single-phonon detection.

Primordial neutrino-antineutrino asymmetries can be constrained through big-bang nucleosynthesis (BBN) relic abundances and cosmic microwave background (CMB) anisotropies, both observables being sensitive to neutrino properties. The latter constraint, which is due to gravitational effects from all neutrino flavors, is very minute since it is at least quadratic in the asymmetries. On the contrary, the constraints from primordial abundances presently dominate, although these abundances are almost only sensitive to the electron flavor asymmetry. It is generally assumed that neutrino asymmetries are sufficiently averaged by flavor oscillations prior to BBN, which allows one to constrain a common primordial neutrino asymmetry at the epoch of BBN. This simplified approach suffers two caveats that we deal with in this article, combining a neutrino evolution code and BBN calculation throughout the MeV era. First, flavor “equilibration” is not true in general, therefore an accurate dynamical evolution of asymmetries is needed to connect experimental observables to the primordial asymmetries. Second, the approximate averaging of asymmetries through flavor oscillations is associated to a reheating of the primordial plasma. It is therefore crucial to correctly describe the interplay between flavor equilibration and neutrino decoupling, as an energy redistribution prior to decoupling does not significantly alter the final effective number of neutrino species’ value. Overall, we find that the space of allowed initial asymmetries is generically unbound when using currently available primordial abundances and CMB measurements. We forecast constraints using future CMB experiment capabilities, which should reverse this experimental misfortune.

We study the effects of long wavelength entropy fluctuations on cosmological probes such as galaxy clustering, luminosity distance, and cosmic microwave background (CMB) temperature anisotropies. Specifically, we consider fluctuations of a massless spectator scalar field setup in the early Universe, which later acquires mass during the radiation-dominated era. We find that there are nonvanishing effects on observables, and the amplitude of these effects peaks for observables setup at the time of equal matter and radiation, and decreases as ${\eta }^{-2}$ where $\eta$ is the conformal time. Hence, the backreaction effects are important for CMB anisotropies, but their impact on late-time observables is suppressed. In particular, the backreaction effects are unable to explain the Hubble tension while they might alleviate the cosmic dipole tension. In contrast to a lot of the previous work on backreaction, we work in position rather than momentum space.

Non-Gaussianity of the primordial curvature perturbations may arise from a variety of well motivated early Universe scenarios. In particular, inflationary theories with additional light degrees of freedom can generate a bispectrum that is peaked in the squeezed limit. While the presence of an additional massless scalar can produce local-type primordial non-Gaussianity, in general the squeezed limit of the bispectrum depends on the mass of the new degree of freedom, and can deviate from the local shape. The resulting bispectrum leaves a distinct imprint on the amplitude and scale dependence of the galaxy bias, which for massive fields can differ from the $k^{-2}$ scaling from local type non-Gaussianity, providing an observational window into the physics of the early Universe. In this work we demonstrate that kinematic Sunyaev-Zeldovich (kSZ) tomography with next generation cosmological surveys will offer significant additional constraining power for both the shape and amplitude of scale-dependent bias arising from primordial non-Gaussianity beyond the local type. We show that this improved constraining power is robust to various obstacles such as the optical depth degeneracy, photometric redshift errors, and uncertainty in the galaxy bias model. With cosmic microwave background S4 and the Large Synoptic Survey Telescope, we forecast that compared to the galaxy survey alone the addition of kSZ tomography will offer a roughly factor of 2 reduction in the measurement uncertainty of the amplitude $f_{NL}$ of primordial non-Gaussianity well beyond the local (massless) limit. We find that kSZ tomography extends the range of masses for which order unity constraints on $f_{NL}$ are achievable, as well as extending the range of masses for which the late time probes of the matter power spectrum outperform the sensitivity of the cosmic microwave background itself.

We present the application of the $n$th order Eulerian perturbation theory ($n\mathrm{EPT}$) for modeling the matter bispectrum in real space as an advancement over the standard perturbation theory (SPT). The $n\mathrm{EPT}$ method, detailed in Wang et al. [Phys. Rev. D 107, 103534 (2023)], sums up the density perturbations up to the $n$th order before computing summary statistics such as bispectrum. Taking advantage of grid-based calculation of SPT (GridSPT), we make a realization-based comparison of the analytical nonlinear bispectrum predictions from $n\mathrm{EPT}$ and SPT against a suite of $N$-body simulations. Using a spherical-bispectrum visualization scheme, we show that $n\mathrm{EPT}$ bispectrum matches better than SPT bispectrum over a wide range of scales in general $w\mathrm{CDM}$ cosmologies. Like the power spectrum case, we find that $n\mathrm{EPT}$ bispectrum modeling accuracy is controlled by ${\sigma }_8(z)\equiv {\sigma }_{8}D(z)$, where $D(z)$ is the linear growth factor at a redshift $z$. Notably, the 6EPT doubles the bispectrum model’s validity range compared to the one-loop SPT for ${\sigma }_8(z)<0.5$, corresponding to redshifts $z\ge 1$ for the best-fitting Planck-2018 cosmology. For $n\ge 5$, however, $n\mathrm{EPT}$ bispectrum depends sensitively on the cut-off scale or the grid resolution. The percent-level modeling accuracy achieved for the spherical bispectrum (where we average over all triangular configurations) becomes much degraded when fixing configurations. Thus, we show that the validity range of the field-level cosmological inferences must be different from that derived from averaged summary statistics such as $n$-point correlation functions.