In this paper, we extend the Standard Model (SM) scalar sector with scalar leptoquarks (LQ) as a portal to the dark sector to resolve some observational anomalies simultaneously. We introduce LQ coupling to scalar dark matter (DM) to suggest an exotic decay channel for the neutron into scalar DM and an SM antineutrino. If the branching ratio of this new neutron decay channel is 1%, a longstanding discrepancy in the measured neutron lifetime between two different experimental methods, bottle and beam experiments, can be solved. The mass of the scalar DM produced from neutron decay should be in a narrow range and as a result, its production in the early universe is challenging. We discuss that the freeze-in mechanism can produce this scalar DM in the early universe with the correct relic abundance. Then we show that the model can explain other SM anomalies like the muon ($g-2$), and $R_{D^{(*)}}$ anomaly simultaneously.

In this work, we investigate the parameter space of the Georgi-Machacek (GM) model, where we consider many theoretical and experimental constraints such as the perturbativity, vacuum stability, unitarity, electroweak precision tests, the Higgs diphoton decay, the Higgs total decay width, and the LHC measurements of the signal strengths of the SM-like Higgs boson $h$ in addition to the constraints from doubly charged Higgs bosons and Drell-Yan di-photon production and the indirect constraint from the $b\to s$ transition processes. We investigate also the possibility that the electroweak vacuum could be destabilized by unwanted wrong minima that may violate the $CP$ and/or the electric charge symmetries. We found that about 40% of the parameter space that fulfills the above mentioned constraints are excluded by these unwanted minima. In addition, we found that the negative searches for a heavy resonance could exclude a significant part of the viable parameter space, and future searches could exclude more regions in the parameter space.

We investigate a separability criterion based on the computable cross-norm (CCNR), and a related quantity called the CCNR negativity. We introduce a reflected version of the CCNR negativity, and discuss its connection with other well-established entanglement-related quantities, namely the reflected entropy and the operator entanglement entropy. For free fermionic and bosonic theories, we derive exact formulas in terms of two-point correlation functions, which allow for systematic numerical investigations and, in principle, analytical treatments. For systems with a global $U(1)$ symmetry, we study the symmetry-resolved reflected entropy and CCNR negativity. We provide conformal field theory results for the charged moments in the case of adjacent intervals, finding perfect agreement with the numerics. We observe an equipartition of reflected entropies and CCNR negativities, both for free-fermions and free-boson models. The first charge-dependent corrections are conjectured for fermions and worked out from the conformal field theory calculations for bosons.

We derive the equations of motion for the bulk-to-boundary propagators of the anti-de Sitter (AdS) boson and fermion fields with arbitrary total angular momentum $J$ in a soft-wall AdS/QCD model and solve it analytically. It provides the opportunity to study transition form factors induced by these bulk-to-boundary propagators, both for on-shell and off-shell hadrons. This is a continuation of our study of hadron form factors induced by the bulk-to-boundary propagator with total angular momentum $J=1$ (e.g., electromagnetic form factors of mesons, nucleons, and nucleon resonances).

We analyze how gauge fixing, required by any practical continuum approach to gauge systems, can interfere with the physical symmetries of such systems. In principle, the gauge fixing procedure, which deals with the (unphysical) gauge symmetry, should not interfere with the other (physical) symmetries. In practice, however, there can be an interference which takes two different forms. First, depending on the considered gauge and on the considered physical symmetry, it might not always be simple or possible to devise approximation schemes that preserve the symmetry constraints on (gauge-independent) observables. Second, even at an exact level of discussion, the (gauge-dependent) effective action for the gauge field, and thus the related vertex functions, may not reflect the physical symmetries of the problem. We illustrate these difficulties using a very general class of gauge fixings that contains the usual gauge fixings as particular cases. Using background field techniques, we then propose specific gauge choices that allow one to keep the physical symmetries explicit, both at the level of the observables and at the level of the effective action for the gauge field. Our analysis is based on the notion of invariance modulo gauge transformations. This is not only a convenient framework to discuss symmetries in the presence of unphysical degrees of freedom, but it also allows one to reinterpret certain aspects of gauge theories without the need to invoke the conceptually annoying “breaking of gauge symmetry.”

The discoveries of the $P_{\psi s}^{\mathrm{\Lambda }}(4459)$ and $P_{\psi s}^{\mathrm{\Lambda }}(4338)$ as the potential ${\mathrm{\Xi }}_c{\overline{D}}^{(*)}$ molecules have sparked our curiosity in exploring a novel class of molecular $P_{\psi s}^{\mathrm{\Lambda }/\mathrm{\Sigma }}$ pentaquarks. In this study, we carry out an investigation into the higher molecular pentaquarks, specifically focusing on the $P_{\psi s}^{\mathrm{\Lambda }/\mathrm{\Sigma }}$ states arising from the ${\mathrm{\Xi }}_c^{(\prime ,*)}{\overline{D}}_1/{\mathrm{\Xi }}_c^{(\prime ,*)}{\overline{D}}_2^{*}$ interactions. Our approach employs the one-boson-exchange model, incorporating both the $S\text{−}D$ wave mixing effect and the coupled channel effect. Our numerical results suggest that the ${\mathrm{\Xi }}_c{\overline{D}}_1$ states with $I(J^P)=0(1/2^{+},3/2^{+})$, the ${\mathrm{\Xi }}_c{\overline{D}}_2^{*}$ states with $I(J^P)=0(3/2^{+},5/2^{+})$, the ${\mathrm{\Xi }}_c^{\prime }{\overline{D}}_1$ states with $I(J^P)=0(1/2^{+},3/2^{+})$, the ${\mathrm{\Xi }}_c^{\prime }{\overline{D}}_2^{*}$ states with $I(J^P)=0(3/2^{+},5/2^{+})$, the ${\mathrm{\Xi }}_c^{*}{\overline{D}}_1$ states with $I(J^P)=0(1/2^{+},3/2^{+},5/2^{+})$, and the ${\mathrm{\Xi }}_c^{*}{\overline{D}}_2^{*}$ states with $I(J^P)=0(1/2^{+},3/2^{+},5/2^{+},7/2^{+})$ can be recommended as the most promising molecular $P_{\psi s}^{\mathrm{\Lambda }}$ pentaquark candidates, and there may exist the potential molecular $P_{\psi s}^{\mathrm{\Sigma }}$ pentaquark candidates for several isovector ${\mathrm{\Xi }}_c^{(\prime ,*)}{\overline{D}}_1/{\mathrm{\Xi }}_c^{(\prime ,*)}{\overline{D}}_2^{*}$ states. With the higher statistical data accumulation at the LHCb’s run II and run III status, there is the possibility that our predicted $P_{\psi s}^{\mathrm{\Lambda }/\mathrm{\Sigma }}$ states can be detected through the weak decay of the ${\mathrm{\Xi }}_b$ baryon, especially in hunting for the predicted $P_{\psi s}^{\mathrm{\Lambda }}$ states.

Black hole images are theoretically predicted—under mild astrophysical assumptions—to display a stack of lensed “photon rings” that carry information about the underlying spacetime geometry. Despite vigorous efforts, no such ring has been observationally resolved thus far. However, planning is now actively under way for space missions targeting the first (and possibly the second) photon rings of the supermassive black holes M87* and Sgr A*. In this work, we study interferometric photon ring signatures in time-averaged images of Kerr black holes surrounded by different astrophysical profiles. We focus on the first, most easily accessible photon ring, which has a larger width-to-diameter ratio than subsequent rings and whose image consequently lacks a sharply defined diameter. Nonetheless, we show that it does admit a precise angle-dependent diameter in visibility space, for which the Kerr metric predicts a specific functional form that tracks the critical curve. We find that a measurement of this interferometric ring diameter is possible for most astrophysical profiles, paving the way for precision tests of strong-field general relativity via near-future observations of the first photon ring.

We study a model of symmetric teleparallel gravity that is able to account for the current accelerated expansion of the Universe without the need for a dark energy component. We investigate this model by making use of dynamical system analysis techniques to identify the regions of the parameter space with viable cosmologies and constrain it using type-Ia supernovae (SnIa) and cosmic microwave background (CMB) data, and make forecasts using standard siren (SS) events. We conclude that this model is disfavored with respect to $\mathrm{\Lambda }\mathrm{CDM}$, and forthcoming standard siren events can be decisive in testing the viability of the model.

We present an approximate treatment of the mixing between ${\nu }_{\tau }$ (${\overline{\nu }}_{\tau }$) and a sterile species ${\nu }_s$ (${\overline{\nu }}_s$) with a vacuum mass-squared difference of $\sim {10}^2–{10}^3{\mathrm{keV}}^2$ in protoneutron stars created in core-collapse supernovae. Including production of sterile neutrinos through both resonant flavor conversion and collisions, we track the evolution of the ${\nu }_{\tau }$ lepton number due to both escape of sterile neutrinos and diffusion. Our approach provides a reasonable treatment of the pertinent processes discussed in previous studies and serves a pedagogical purpose to elucidate the relevant physics. We also discuss refinements needed to study more accurately how flavor mixing with sterile neutrinos affects protoneutron star evolution.

We study the $W$ boson associated single top quark production at the Large Hadron Collider to probe anomalous chromomagnetic and chromoelectric moments of the top quark with the help of polarization and spin correlation observables besides the cross section in the leptonic final state. We reconstruct the two neutrinos in the final state using the $M_{T2}$ assisted on-shell reconstruction method to measure the polarization and spin correlation asymmetries of the top quark and the $W$ boson. We estimate the limits on the anomalous moments in a detector-level simulation considering possible backgrounds for a few sets of integrated luminosities and examine the effect of systematic uncertainties.

We search for the $B^0\to p{\overline{\mathrm{\Sigma }}}^0{\pi }^{-}$ decay with ${\overline{\mathrm{\Sigma }}}^0\to \overline{\mathrm{\Lambda }}\gamma$, where the $\gamma$ is not measured, using a data sample corresponding to an integrated luminosity of $711\mathrm{f}{\mathrm{b}}^{-1}$ which contains $772\times {10}^{6}B\overline{B}$ pairs, collected around the $\mathrm{\Upsilon }(4\mathrm{S})$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We measure for the first time the $B^0\to p{\overline{\mathrm{\Sigma }}}^0{\pi }^{-}$ branching fraction to be $\mathcal{B}(B^0\to p{\overline{\mathrm{\Sigma }}}^0{\pi }^{-})=(1.17_{-0.40}^{+0.43}(\mathrm{stat})\pm 0.07(\mathrm{syst}))\times {10}^{-6}$ with a significance of $3.0\sigma$. We simultaneously measure the branching fraction for the related channel $B^0\to p\overline{\mathrm{\Lambda }}{\pi }^{-}$ with much improved precision.

We present a covariant quantization scheme for the so-called “partially massless” graviton field in de Sitter spacetime. Our approach is founded on the principles of the de Sitter group representation theory (in the sense given by Wigner), the Wightman-Gärding axioms for gauge-invariant fields (Gupta-Bleuler scheme), and the essential analyticity prerequisites in the complexified pseudo-Riemannian manifold. To implement the quantization process effectively, we adopt coordinate-independent (global) de Sitter plane waves. These plane waves, defined in the appropriate tube domains of complex de Sitter spacetime, serve as the de Sitter counterparts to the standard Minkowskian plane waves. By employing these analytical plane waves, we enable a spectral analysis of the corresponding two-point function that closely resembles the Fourier analysis typically employed in the flat Minkowskian case. Within this framework, we present the Wightman two-point function for the partially massless graviton field, which satisfies the essential criteria of locality, covariance, and normal analyticity. Furthermore, we provide insights into the underlying Hilbert space structure and the corresponding unsmeared field operator. A direct consequence of this quantization construction confirms the widely accepted notion of light-cone propagation for the de Sitter partially massless graviton field.

Fermion soliton stars are a motivated model of exotic compact objects in which a nonlinear self-interacting real scalar field couples to a fermion via a Yukawa term, giving rise to an effective fermion mass that depends on the fluid properties. Here we continue our investigation of this model within general relativity by considering a scalar potential with generic asymmetric vacua. This case provides fermion soliton stars with a parametrically different scaling of the maximum mass relative to the model parameters, showing that the special case of symmetric vacua, in which we recover our previous results, requires fine tuning. In the more generic case studied here the mass and radius of a fermion soliton star are comparable to those of a neutron star for natural model parameters at the GeV scale. Finally, the asymmetric scalar potential inside the star can provide either a positive or a negative effective cosmological constant in the interior, being thus reminiscent of gravastars or anti–de Sitter bubbles, respectively. In the latter case we find the existence of multiple, disconnected, branches of solutions.

The Galactic flux of cosmic-ray (CR) positrons in the GeV to TeV energy range is very likely due to different Galactic components. One of these is the inelastic scattering of CR nuclei with the atoms of the interstellar medium. The precise amount of this component determines the eventual contribution from other sources. We present here a new estimation of the secondary CR positron flux by incorporating the latest results for the production cross sections of $e^{\pm }$ from hadronic scatterings calibrated on collider data. All the reactions for CR nuclei up to silicon scattering on both hydrogen and helium are included. The propagation models are derived consistently by fits on primary and secondary CR nuclei data. Models with a small halo size ($L\le 2\mathrm{kpc}$) are disfavored by the nuclei data although the current uncertainties on the beryllium nuclear cross sections may impact this result. The resulting positron flux shows a strong dependence on the Galactic halo size, increasing up to factor 1.5 moving $L$ from 8 kpc to 2 kpc. Within the most reliable propagation models, the positron flux matches the data for energies below 1 GeV. We verify that secondary positrons contribute less than 70% of the data above a few GeV, corroborating that an excess of positrons is already present at very low energies. At larger energies, our predictions are below the data with the discrepancy becoming more and more pronounced. Our results are provided together with uncertainties due to propagation and hadronic cross sections. The former uncertainties are below 5% at fixed $L$, while the latter are about 7% almost independently of the propagation scheme. In addition to the predictions of positrons, we provide new predictions also for the secondary CR electron flux.

Single particle detection is described in a limited way by simple models of measurements in quantum field theory. We show that a general approach, using Kraus operators in spacetime constructed from natural combinations of fields, leads to an efficient model of a single particle detector. The model is free from any auxiliary objects as it is defined solely within the existing quantum field framework. It can be applied to a large family of setups where the time resolution of the measurement is relevant, such as Bell correlations or sequential measurement. We also discuss the limitations and working regimes of the model.

$Q$-balls are bound-state configurations of complex scalars stabilized by a conserved Noether charge $Q$. They are solutions to a second-order differential equation that is structurally identical to Euclidean vacuum-decay bounce solutions in three dimensions. This enables us to translate the recent tunneling potential approach to $Q$-balls, which amounts to a reformulation of the problem that can simplify the task of finding approximate and even exact $Q$-ball solutions.

In addition to vector ($V$) type new particles extensively discussed previously, both $CP$-even ($S$) and $CP$-odd ($P$) spin-0 dark matter (DM) mediators can couple to muons and be produced in the bremsstrahlung reaction ${\mu }^{-}+N\to {\mu }^{-}+N+S(P)$. Their possible subsequent invisible decay into a pair of Dirac DM particles, $S(P)\to \chi \overline{\chi }$, can be detected in fixed target experiments through missing energy signature. In this paper, we focus on the case of experiments using high-energy muon beams. For this reason, we derive the differential cross sections involved using the phase space Weiszäcker-Williams approximation and compare them to the exact-tree-level calculations. The formalism derived can be applied in various experiments that could observe muon-spin-0 DM interactions. This can happen in present and future proton beam-dump experiments such as NA62, SHIP, HIKE, and SHADOWS; in muon fixed target experiments as $\mathrm{NA}64\mu$, MUonE and M3; in neutrino experiments using powerful proton beams such as DUNE. In particular, we focus on the $\mathrm{NA}64\mu$ experiment case, which uses a 160 GeV muon beam at the CERN Super Proton Synchrotron accelerator. We compute the derived cross sections, the resulting signal yields and we discuss the experiment projected sensitivity to probe the relic DM parameter space and the $(g-2{)}_{\mu }$ anomaly favored region considering ${10}^{11}$ and ${10}^{13}$ muons on target.

The CDF Collaboration recently reported a new precise measurement of the $W$-boson mass $M_W$ with a central value significantly larger than the SM prediction. We explore the effects of including this new measurement on a fit of the Standard Model (SM) to electroweak precision data. We characterize the tension of this new measurement with the SM and explore potential beyond the SM phenomena within the electroweak sector in terms of the oblique parameters $S$, $T$ and $U$. We show that the large $M_W$ value can be accommodated in the fit by a large, nonzero value of $U$, which is difficult to construct in explicit models. Assuming $U=0$, the electroweak fit strongly prefers large, positive values of $T$. Finally, we study how the preferred values of the oblique parameters may be generated in the context of models affecting the electroweak sector at tree and loop level. In particular, we demonstrate that the preferred values of $T$ and $S$ can be generated with a real ${\mathrm{SU}(2)}_L$ triplet scalar, the humble swino, which can be heavy enough to evade current collider constraints, or by (multiple) species of singlet-doublet fermion pairs. We highlight challenges in constructing other simple models for explaining a large $M_W$ value and several directions for further study.