A new technique is developed to identify dielectrons ( e + e − ) with Lorentz boost γ L > 20 that produce one single merged cluster in the electromagnetic calorimeter of the CMS detector. The identification uses two multivariate models: one for the case where both electron tracks are reconstructed, and another where only one of the tracks is reconstructed. The efficiency is determined using proton-proton collision data collected at a center-of-mass energy of 13 TeV. Boosted J / ψ mesons decaying into e + e − pairs are used to estimate the efficiency of the model with two tracks, yielding an overall efficiency of 80%. The Z → μ + μ − γ events, where the photon converts into a collimated dielectron, are used for the model with a single track, yielding an efficiency of about 60%. A dedicated energy correction for dielectron candidates is also developed using B ± → J / ψ K ± → e + e − K ± data.
Future gravitational-wave detectors, such as the Einstein Telescope and Laser Interferometer Gravitational Wave Observatory (LIGO) Voyager, are planned to implement cryogenic technology. For the Kamioka gravitational wave detector, where cryogenics has already been adopted, issues related to the growth of an ice layer on mirror surfaces were reported. Further studies have confirmed the presence of nanometric layers in cryogenic experiments in which ice led to an increase in optical loss and to oscillations of the mirror reflectance. In this study, we investigate the mechanical loss of an ice layer grown on a silicon substrate. The results show that the total mechanical loss increases over time with the thickness of the ice layer, indicating that even a few nanometers of ice can impact the sensitivity of gravitational-wave detectors.
More than one dark sector particle transforming under the same symmetry provides one stable dark matter (DM) component, which undergoes coannihilation with the heavier particle(s) decaying to DM. Specific assumptions on the kinematics and on the coupling parameters may render the heavier component(s) stable and contribute as DM. The choices of the charges of the dark sector fields under transformation play a crucial role in the resultant phenomenology. In this paper, we systematically address the possibility of obtaining two scalar DM components under Z N symmetry. We consider both the possibilities of DM being weakly interacting massive particles (WIMPs) or pseudofeebly interacting massive particles (pFIMPs). We elaborate upon the Z 3 symmetric model, confronting the relic density-allowed parameter space with the recent most direct and indirect search bounds and prospects. We also highlight the possible distinction of the allowed parameter space in single component and two-component cases as well as between WIMP-WIMP and WIMP-pFIMP scenarios.
In this paper, we revisit the smoothness of the classical limit of inclusive observables in the formalism developed by Kosower, Maybee and O’Connell (KMOC). Building on the earlier work, we prove that the classical limit of three classes of inclusive observables, namely scattering angle, radiative field, and angular impulse is smooth and does not suffer from any so-called superclassical divergences at all orders in perturbation. We use scalar QED as a model. Our analysis goes some way in showing that KMOC formalism can be used to compute classical radiation by simply focusing on all the terms that scale as ℏ 0 , as all the terms that scale with inverse power of ℏ vanish. Through this analysis, we have successfully isolated the classes of terms that contribute to the classical limit, thereby allowing direct and more efficient computations of physical observables.
We explore the sensitivity of the Sudbury Neutrino Observatory (SNO) experiment to light dark matter particles χ with spin-dependent interactions with nucleons. We show that the pair-production of MeV scale dark matter is possible in heavy water (CANDU (Canada Deuterium Uranium)) reactors via D ( n , χ χ ¯ ) He 3 , and calculate the expected rate within the simplest models of χ -nucleon interactions. Owing to a sizable Q -value for this reaction, a large fraction of dark matter (DM) particles produced this way are above the threshold for deuteron disintegration, D ( χ , χ ) n p , which adds to the SNO neutral current signal. Evaluating the CANDU-to-SNO scheme for the production and detection of DM, we derive novel constraints for the χ -nucleon spin-dependent cross sections, showing that cross sections above σ χ p ∼ 10 − 33 cm 2 are generally excluded if m χ ≤ 1.5 MeV . An isospin-mirror reaction will occur in the Sun, and for the kinematically allowed region it excludes a portion of parameter space with cross sections on the order 10 − 37 cm 2 . We also evaluate the potential sensitivity of small “near” detectors placed in close proximity to a CANDU reactor to search for a coherent nuclear recoil, finding subdominant sensitivity.
We develop a semiclassical framework to determine scaling dimensions of neutral composite operators in scalar conformal field theories. For the critical Ising λ ϕ 4 theory in d = 4 − ε , we obtain the full spectrum of composite operators built out of n fields transforming according to the various Lorentz representations to next-to-leading order in the double-scaling limit n → ∞ and λ → 0 with λ n fixed. At any given order, the semiclassical expansion resums an infinite number of Feynman diagrams. Combining our results with existing perturbative computations further yields the complete five-loop scaling dimensions in the ε -expansion for the family of ϕ n operators. Finally, extrapolating the semiclassical results to three dimensions leads to a competitive alternative to existing methodologies.
A systematic way to constructing optimized interpolating operators for two-hadron systems is developed by incorporating interhadron spatial wave functions. The wave functions can be obtained from an iterative process with an appropriate initial guess. To implement these operators, a novel quark smearing technique utilizing Z 3 noise vectors is proposed, which allows for effectively incorporating interhadron spatial wave functions at the source without using all-to-all quark propagators. Proof-of-principle application to the Ω c c c Ω c c c system using physical-point lattice configurations with a large size L a ≃ 8.1 fm demonstrates that optimized operators outperform combinations of limited plane wave operators in the variational analysis, enabling clear identification of states around 2 m Ω c c c ≃ 9700 MeV with the energy gap as narrow as ∼ 5 MeV . A comparison on correlation functions, effective energies, and HAL QCD potentials between unoptimized operators and optimized operators is given, with a special emphasis on the effects from nearby elastic scattering states. Potential applicability of the optimized operator to various two-hadron systems and its relation to the variational method are also discussed.
Extreme astrophysical environments provide unique laboratories for testing fundamental neutrino interactions. We present the first oscillation-independent astrophysical probe of nonstandard neutrino interactions (NSI), using coincident neutral-current signals across diverse detectors to break degeneracies that have long limited sensitivity reach. Using self-consistent NSI supernova simulations and flavor-independent neutral-current scattering we show that anticorrelated signatures between JUNO liquid scintillator and dark matter detectors such as DARWIN/XLZD, ARGO, or RES-NOVA enable clear discrimination between NSI and flavor-conversion effects. For a Galactic supernova at Betelgeuse distance our approach enables an independent probe of neutrino-quark NSI couplings in parameter space that can reach and extend beyond current terrestrial limits. This multidetector approach enables breaking degeneracies in terrestrial searches and is broadly applicable to a wide range of upcoming experiments, establishing a new principle for testing fundamental interactions with astrophysical data.
We perform a complete one-loop renormalization analysis of C P T -odd Lorentz-violating scalar quantum chromodynamics with adjoint scalar matter. Working to first order in the preferred background vector and treating the corresponding operators as perturbative insertions, we compute the ultraviolet-divergent parts of the relevant two-, three-, and four-point Green’s functions for the gauge, scalar, and ghost fields. We show that the gauge sector develops the expected Carroll-Field-Jackiw-type correction, which generically turns out to be divergent in our theory, although the divergence vanishes in a certain gauge, while the scalar sector displays the corresponding C P T -odd single-derivative term proportional to the background vector. We further demonstrate that several of the Lorentz-violating corrections the three- and four-point function are ultraviolet finite. All one-loop divergences may be absorbed into counterterms already allowed by the classical Lagrangian, providing an explicit proof of the multiplicative renormalizability of the theory at this order. We also obtain the associated renormalization constants and one-loop β functions for the gauge coupling, the Lorentz violation parameters, and the scalar self-interaction.
It is pointed out that the vertex operators of a chiral boson in 1 + 1 dimensions provide an explicit realization of dichotomic, bounded, Hermitian operators that saturate the Tsirelson bound of the Bell-Clauser-Horne-Shimony-Holt inequality in the vacuum state.
One of the most intriguing proposals for wave-function collapse is the Diósi-Penrose model, in which collapse is driven by stochastic fluctuations of the Newtonian potential. We argue that a closely related effective structure can emerge in string theory if, as recently suggested, the present cosmic acceleration is sourced by instant folded strings and their decay products. A key difference, however, is that in this stringy setting the noise is naturally colored in time rather than white. As a result, the scenario is significantly less constrained by existing experiments than the standard Diósi-Penrose model.
We identify the complete set of fundamental building blocks for a 4D pregeometric theory of gravity. Based on a gauge theory of S O ( 1 , 4 ) or S O ( 2 , 3 ) coupled to a Higgs-like field under the rigid constraint of general covariance in the unbroken phase, these building blocks ( L MM , L W , L J , L θ , and L ϑ ) constitute the minimal generating set of independent field monomials from which any pregeometric action, including arbitrary functionals thereof, can be constructed. While the most general pregeometric theory can extend beyond linear combinations, these five irreducible invariants serve as the “atomic” constituents of all possible pregeometric dynamics. Upon spontaneous symmetry breaking, they collectively generate an emergent gravitational theory consisting of the Einstein-Hilbert action, the cosmological constant term, and all 4D topological invariants: the Gauss-Bonnet, Pontryagin, Holst, and Nieh-Yan terms. The unification of gravity’s dynamical and topological sectors from a common pregeometric source represents the central result of this work. We also uncover a seesaw mechanism linking the Planck mass and the cosmological constant, as well as several novel relations for the coupling constants of the topological sector, inclusive of the Barbero-Immirzi parameter. This framework establishes the pregeometric foundations from which all aspects of gravitation can dynamically emerge, providing a unified starting point for quantum gravity, dark energy phenomenology, and the study of topological phases in gravitational theories.
We investigate the properties of charged black hole geometries in nonlinear electrodynamics. We focus on the recently reported analytic charged black hole solutions to illustrate the consequences of a nonmonotonic lapse function that exists for a wide range of black hole solutions. The spacetime admits stable light-rings, static near-horizon observers, and trapped near horizon photon orbits. We also show that although these modifications near the horizon are screened from afar, they nonetheless lead to additional branches of quasinormal modes for the black hole that are longer lived than the canonical Einstein branches.
Using a dataset of 7.33 fb − 1 of e + e − annihilation data collected with the BESIII detector at center-of-mass energies from 4.128 to 4.226 GeV, we report an updated measurement of the branching fraction of D s + → τ + ν τ via four τ + decay modes: τ + → e + ν e ν ¯ τ , μ + ν μ ν ¯ τ , π + ν ¯ τ , and π + π 0 ν ¯ τ . The branching fraction is determined to be B ( D s + → τ + ν τ ) = ( 5.37 ± 0.0 8 stat ± 0.0 6 syst ) % . The product of the modulus of the Cabibbo-Kobayashi-Maskawa matrix element | V c s | and the D s + decay constant f D s + is measured to be f D s + | V c s | = ( 248.2 ± 1.9 stat ± 1.4 syst ± 0.6 input ± 0.8 EM ) MeV . Both the branching fraction and the product f D s + | V c s | are the most precise results yet obtained. Then, taking f D s + from lattice quantum chromodynamics calculations results in | V c s | = 0.993 ± 0.00 8 stat ± 0.00 6 syst ± 0.00 3 input ± 0.00 3 EM . Conversely, one finds f D s + = ( 255.0 ± 1.9 stat ± 1.4 syst ± 0.6 input ± 0.8 EM ) MeV when taking | V c s | from the CKMfitter group as an input. Combining with the world average value of D s + → μ + ν μ , the ratio of the branching fractions between D s + → τ + ν τ and D s + → μ + ν μ is estimated to be 10.04 ± 0.29 , which is consistent with the Standard Model prediction of lepton flavor universality.
In the present work, we investigate the molecular properties of the hidden charm pentaquark states P c and P c s with a coupled-channel framework that combines heavy quark spin symmetry and the local hidden gauge formalism. By solving the Bethe-Salpeter equation with the cutoff method, we obtain the pole trajectories, wave functions, and root-mean-square radii. For the hidden charm system, the full coupled-channel interactions respecting the heavy quark spin symmetry are essential to generate the P c states, which significantly affect the poles’ widths. The dominant bound channels are D ¯ Σ c and D ¯ * Σ c , which couple strongly to the lower decay channels. In contrast, for the hidden charm strange system, the full heavy quark spin symmetry treatment is not necessary, where the splitting pseudoscalar meson-baryon (PB) and vector meson-baryon (VB) sectors yield similar results. The main bound channels D ¯ Ξ c and D ¯ * Ξ c couple strongly to D ¯ s Λ c and D ¯ s * Λ c , respectively, but weakly to the lower decay channels, different from the hidden charm case. The trajectories of the pole widths for the loosely bound channels D ¯ Ξ c ′ , D ¯ * Ξ c ′ , and D ¯ * Ξ c * exhibit distinct behaviors. Notably, all the primary bound channels have similar binding energies in the single-channel interactions due to equally attractive potentials. Furthermore, we also calculate the wave functions and root-mean-square radii of the corresponding poles. The wave functions are localized within 0 ∼ 6 fm and vanish fast beyond 4 fm. The root-mean-square radii, evaluated by two consistent methods, typically lie between 0.5 and 2 fm, comparable to the characteristic scale of molecular states. The root-mean-square radii depend on the pole trajectories and differ among the full coupled-channel case, the split PB and VB sectors, and the single-channel interactions.
