In this study, we conducted a systematic analysis of long-term Fermi-LAT $\gamma$-ray data for a sample of blazars, including flat spectrum radio quasars (FSRQs), BL Lacertae objects (BL Lacs), and blazar candidates of unknown type (BCU), to investigate their $\gamma$-ray variability. We focused on light curves binned in three-day, seven-day, and 30-day intervals to assess the impact of binning on variability, using data with $TS>4$ as a detection threshold. We calculated fractional variability (${\mathrm{F}}_{\mathrm{var}}$) for each category and found that FSRQs exhibit higher mean variability compared to BL Lacs and BCUs, with BCUs displaying intermediate variability closer to BL Lacs. The Kolmogorov-Smirnov test on the variability distributions of FSRQs, BL Lacs, and BCUs indicates that FSRQs differ from both BL Lacs and BCUs, whereas BCUs are more similar to BL Lacs. The observed higher variability in FSRQs is likely linked to more powerful jets and accretion processes. The correlation between $\gamma$-ray flux and spectral index suggests a moderate positive correlation for BL Lacs and BCUs, indicating a “softer when brighter” behavior. FSRQs, however, displayed a mild anticorrelation, suggesting a tendency for these sources to become harder as their flux increases. Additionally, the analysis of flux distributions revealed log-normal behavior in many sources, consistent with multiplicative variability processes in blazar jets. Some sources exhibit bimodal distributions, implying transitions between distinct emission states. Moreover, binning effects the observed variability, with longer bins smoothing short-term fluctuations. The power spectral density (PSD) analysis suggested that FSRQs exhibit steeper slopes, reflecting structured variability, while BL Lacs display shallower slopes, dominated by stochastic processes. The absence of PSD breaks suggests no dominant characteristic timescale within the Fermi window. Spectral index distributions further highlight complexity, often requiring multicomponent models.

The inspiral range is the most common metric for characterizing the performance of ground-based gravitational-wave interferometers. However, there is no clear formalism for working with similar quantities that describe the frequency-dependent astrophysical sensitivity of these detectors. We introduce a metric for the cumulative normalized range of a gravitational-wave interferometer, as well as methods to compare two separate noise curves. We show how this metric is a valuable tool for understanding the impact of commissioning of these interferometers and provides increased clarity compared to other commonly used approaches.

We present the first analysis of dark matter axion detection applying neural networks for the improvement of sensitivity. The main sources of thermal noise from a typical readout chain are simulated, constituted by resonant and amplifier noises. With this purpose, an advanced modal method employed in electromagnetic modal analysis for the design of complex microwave circuits is applied. A feedforward neural network is used for a Boolean decision (there is axion or only noise), and robust results are obtained: the neural network can improve by a factor of $5\times {10}^3$ the integration time needed to reach a given signal to noise ratio. This could either significantly reduce measurement times or achieve better sensitivities with the same exposure durations.

We study the $1+1$ flat spacetime dynamics of a classical field configuration corresponding to an ensemble of sine-Gordon kinks and antikinks, semiclassically coupled to a quantum field. This coupling breaks the integrability of the sine-Gordon model resulting in the background’s decay into quantum radiation as kink-antikink pairs annihilate. We find evidence that, on average, the energy of the ensemble scales as $t^{-\alpha }$ with $\alpha <1$ and independent of the coupling strength or the mass of the quantum field. The generalization of this result to domain wall networks in higher spacetime dimensions could be relevant to particle production in the early universe.

We revisit the doublet–triplet splitting problem within the $SU(5)$ gauge group framework to advocate a viable regime with the light scalar leptoquark of the doublet–triplet splitting notoriety that is compatible with the current experimental bounds on partial proton decay lifetimes. We explicitly demonstrate, through a consistent use of higher-dimensional operators, how to implement suppression of baryon number violating interactions of the aforementioned color triplet. Our study thus offers an alternative approach to the doublet-triplet splitting problem as it removes a need for an extreme mass hierarchy between the partners residing in the same representation. We furthermore pursue two different extensions of two distinct symmetry breaking scenarios of $SU(5)$, one with a 24-dimensional representation and the other one with a 75-dimensional representation, to produce comparative study of novel consequences for the gauge coupling unification and the one-loop level neutrino mass generation. Our results point toward qualitatively novel $SU(5)$ scenarios, where the light scalar leptoquarks, responsible for the neutrino mass generation, might be even accessible at colliders and thus serve as an accelerator accessible portal to the high-scale physics.

We study the Higgs couplings involved in the $Zh$ associated production mode at the Large Hadron Collider (LHC) in presence of Higgs-gauge boson coupling modifiers via $\kappa$ framework and dimension-six Standard Model (SM) effective theory operators. The analysis is performed mainly in the context of the High-Luminosity LHC (with $\sqrt{s}=14\mathrm{TeV}$ and luminosity $3000{\mathrm{fb}}^{-1}$) setup using cut-based as well as machine learning techniques. The analysis shows significant betterment in the signal significance by using the machine learning technique. We also do a ${\chi }^2$ analysis, which reveals an appreciable change in the sensitivity of the coupling modifiers due to the presence of effective operators, in particular, due to the $qqZh$ Higgs-current interactions. The dipole operators concerning the same vertex combine quarks of different chiralities and do not interfere with the SM diagrams, hence contributing only at $\mathcal{O}({\mathrm{\Lambda }}^{-4})$. In order to observe better sensitivity for this class of operators, we need to move to higher center-of-mass energy, where the effects of both Higgs-current and dipole four-point interactions are more prominent.

We study the production of a $CP$-even flavon $H_F$ in proton-proton collisions and the prospects for its detection via the diphoton channel at future super hadron colliders, i.e., $pp\to H_F\to \gamma \gamma$. The theoretical framework adopted is a model that invokes the Froggatt-Nielsen mechanism with an Abelian flavor symmetry, which includes a Higgs doublet and a complex singlet. We confront the free parameters of the model against theoretical and experimental constraints to find the allowed parameter space, which is then used to evaluate the production cross section of the flavon and the branching ratio of its decay into two photons. We find promising results based on specific benchmark points, achieving signal significances at the level of $5\sigma$ for flavon masses in the interval $200\lesssim M_{H_F}\lesssim 450$ and integrated luminosities in the range $5–12{\mathrm{ab}}^{-1}$ at the future High-Energy LHC. On the other hand, the Future Circular Collider-hadron-hadron could probe masses up to 1 TeV if it reaches an integrated luminosity of at least $2{\mathrm{ab}}^{-1}$.

We present a lattice quantum chromodynamics (QCD) calculation of the radiative leptonic decay rates of the kaon, improving upon our previous work in Desiderio et al. [First lattice calculation of radiative leptonic decay rates of pseudoscalar mesons, Phys. Rev. D 103, 014502 (2021)]. Our analysis uses gauge ensembles generated by the Extended Twisted Mass Collaboration (ETMC) with $N_f=2+1+1$ flavors of Wilson-clover twisted mass fermions. For the first time, we go beyond the electroquenched approximation by including quark-disconnected contributions. Several key improvements have been implemented: (i) the simulations are now performed directly at physical light- and strange-quark masses, (ii) finite-size effects are carefully investigated using lattices with spatial extents ranging from $L\simeq 3.8\mathrm{fm}$ to $L\simeq 7.7\mathrm{fm}$, and (iii) the continuum extrapolation is based on three lattice spacings in the range $a\in [0.08,0.058]\mathrm{fm}$. As a result of the high-precision determination of the relevant correlation functions, we reduce the uncertainties on both the axial and vector form factors by nearly a factor of two compared to our previous analysis. When compared to experimental measurements in the electron channel ($K^{-}\to e^{-}{\overline{\nu }}_e\gamma$), our results show a tension—at the level of 2.6 standard deviations—with respect to KLOE data. On the other hand, they are compatible with measurements from the E36 Collaboration at J-PARC. In the muonic decay channel ($K^{-}\to {\mu }^{-}{\overline{\nu }}_{\mu }\gamma$), we confirm the tensions, already observed in our previous study, between lattice QCD predictions and $\mathrm{ISTRA}+$ and OKA data, which are both primarily sensitive to the value of the negative-helicity form factor $F^{-}$.

We present a first-principles lattice QCD investigation of second-order fluctuations of and correlations among conserved charges—baryon number (B), electric charge (Q), and strangeness (S)—in the presence of external magnetic fields. Our study employs lattice simulations of ($2+1$)-flavor QCD with physical pion masses using highly improved staggered fermions on ${48}^3\times 12$ and ${32}^3\times 8$ lattices, covering a wide range of magnetic field strengths up to $eB\simeq 0.8{\mathrm{GeV}}^2$. We identify clear signals of magnetic field-induced modifications to these fluctuations and correlations, with the baryon-electric charge correlation, ${\chi }_{11}^{\mathrm{BQ}}$, exhibiting particularly strong sensitivity to the magnetic field. To bridge theoretical predictions with experimental observables, we implement systematic kinematic cuts that emulate detector acceptances of the STAR and ALICE experiments within the hadron resonance gas (HRG) model and construct proxy observables for fluctuations measurable in heavy-ion collision experiments. Our findings highlight ${\chi }_{11}^{\mathrm{BQ}}$ as a promising “magnetometer” for probing the presence of magnetic fields in QCD matter. Furthermore, we explore experimentally relevant ratios involving ${\chi }_{11}^{\mathrm{BQ}}$, demonstrating their potential in mitigating volume effects and enhancing sensitivity to magnetic fields in collision environments. Additionally, we assess the limitations of the HRG model at strong magnetic fields, revealing deviations that indicate nontrivial modifications to hadronic degrees of freedom. These results offer new insights into the interplay between thermal and magnetic effects in the QCD phase diagram and provide experimentally relevant guidance for the detection of magnetic fields in heavy-ion collisions.

We calculate the possible scalar, vector, and tensor form factors (FFs) for pion and kaon in the light-cone quark model (LCQM). These FFs are calculated from the leading and subleading twist generalized parton distribution functions (GPDs) of the pion and kaon. The vector and tensor FFs correspond to twist-2 GPDs, whereas the scalar FFs correspond to twist-3 scalar GPDs. We calculate the FFs from the GPDs quark-quark correlator and express them in the form of light-front wave functions. The behavior of these FFs was found to be in agreement with experimental data, other model predictions, and lattice simulation results. We have also calculated the charge radii corresponding to different FFs and compared them with other models, lattice simulation results, and experimental data. The scalar radii of the pion and kaon of our model are found to be 0.528 and 0.409 fm, respectively.

The magnetic moments, magnetic form factors, and transition magnetic form factors of doubly charmed baryons are studied within heavy baryon chiral perturbation theory. We regulate the loop integrals using the finite-range regularization. The contributions of vector mesons are taken into account to investigate the dependence of form factors on the transferred momentum. The finite volume and lattice spacing effects are considered to analyze the lattice QCD simulations which can be understood well in our framework.

In this article, the vector, axial vector, and tensor form factors of $B_c\to {\chi }_{cJ}$ ($J=0$, 1, 2) and $B_c\to h_c$ are analyzed within the framework of three-point QCD sum rules. With the calculated vector and axial vector form factors, we directly study the decay widths and branching ratios of semileptonic decays $B_c^{-}\to {\chi }_{cJ}l{\overline{\nu }}_l,h_{c}l{\overline{\nu }}_l$ $(l=e$, $\mu$ and $\tau$) and analyze the nonleptonic decays $B_c^{-}\to {\chi }_{cJ}{\pi }^{-},{\chi }_{cJ}{K}^{-},{\chi }_{cJ}{\rho }^{-},{\chi }_{cJ}{K}^{*-}$, $B_c^{-}\to h_c{\pi }^{-},h_c{K}^{-},h_c{\rho }^{-},h_c{K}^{*-}$ by using the naive factorization approach. These results can provide more information to understand the properties of $B_c$ meson and $P$-wave charmonia and to study the heavy quark dynamics.

Based on $(2712.4\pm 14.3)\times {10}^6\psi (3686)$ events collected by the BESIII detector operating at the BEPCII storage ring, we perform a search for the baryon- and lepton-number violating decay $J/\psi \to p{e}^{-}+\mathrm{c}.\mathrm{c}.$ via $\psi (3686)\to {\pi }^{+}{\pi }^{-}J/\psi$. No significant signal is found. An upper limit on the branching fraction of $\mathcal{B}(J/\psi \to p{e}^{-}+\mathrm{c}.\mathrm{c}.)$ is found to be $3.1\times {10}^{-8}$ at 90% confidence level.

We obtain exact expressions for correlation functions of charged scalar operators at finite density and low temperature in ${\mathrm{CFT}}_4$ dual to the $\mathrm{RN}\text{−}{\mathrm{AdS}}_5$ black-brane. We use recent developments in the Heun connection problem in black hole perturbation theory arising from Liouville conformal field theory (CFT) and the Alday-Gaiotto-Tachikawa correspondence. The connection problem is solved perturbatively in an instanton counting parameter, which is controlled in a double-scaling limit where $\omega ,T\to 0$ holding $\omega /T$ fixed. This provides analytic control over the emergence of the zero temperature branch cut as a confluent limit of the Heun equation. From the Green’s function we extract analytic results for the critical temperature of the holographic superconductor, as well as dispersion relations for both gapped and gapless low temperature quasinormal modes. We demonstrate precise agreement with numerics.

Bursts from the very early Universe may lead to a detectable signal via the production of positrons, whose annihilation gives an observable x-ray signal. Using the absorption parameters for the annihilation photons of 511 keV, it is found that observable photons would originate at a redshift around $z\approx 200–300$, resulting in soft x-rays of energy $\sim 2–3\mathrm{keV}$ at present. Positrons are expected to be absent at these times or redshifts in the standard picture of the early universe. Detection of the x-rays would thus provide dramatic support for the hypothesis of the bursts, explosive events at very early times. We urge the search for such a signal.

We present a self-consistent dynamical holographic quantum chromodynamics (QCD) model to investigate the mass spectra and melting behavior of heavy and exotic mesons at finite temperature and finite density. Our approach is based on the Einstein-Maxwell-dilaton (EMD) framework and incorporates an elsewhere already introduced, albeit by hand, phenomenological nonquadratic dilaton profile. This allows one to capture the nonlinear Regge trajectories of heavy-flavor mesons and model certain exotic states. We show how to construct such models by actually solving the coupled Einstein, Maxwell, and dilaton field equations, ensuring mathematical self-consistency to replace any ad hoc input. At finite temperature, we analyze the confinement-deconfinement transition via a Hawking-Page phase transition. We compute the spectral functions, revealing the sequential melting of quarkonia as the temperature is increased. Extending to finite density, we explore the impact of baryon chemical potential on meson stability, showing significant modifications in spectral peaks and effective potentials that indicate a more rapid melting of mesonic states as the chemical potential increases in the deconfined phase. The dual of the small/large black hole transition now indicates toward a first order phase transition line ending at a second order critical point. Interestingly, the spectral functions smoothly cross this phase transition line.

Two variants of $\mathcal{N}=7$ superconformal mechanics with manifest $\mathfrak{so}(7)$ and $\mathfrak{su}(2)\times \mathfrak{su}(2)$ $R$-symmetries possessing exceptional $G(3)$ dynamical symmetry are presented. To construct these $G(3)$ theories, we developed two new versions of covariant embedding of the exceptional ${\mathfrak{g}}_2$ algebra into the $\mathfrak{so}(7)$ algebra and then the embedding of $\mathfrak{so}(7)$ into $\mathfrak{so}(8)$. As a result, two $\mathcal{N}=8$ superconformal mechanics with the $OSp(8|2)$ and $\mathfrak{F}(4)$ superconformal algebras and $\mathcal{N}=7,G(3)$ superconformal mechanics were constructed in a uniform way. The constants of the octonion multiplication play a key role in the construction of superconformal mechanics with manifest $\mathfrak{so}(7)$ symmetry.

We discuss the low-energy properties of binary superfluids with density-dependent interactions. Adding an intraspecies coupling that induces an explicit soft symmetry breaking, we determine the background pressure, and we show that the low-energy spectrum consists of a massless Nambu-Goldstone boson and a massive (pseudo) Nambu-Goldstone boson. When the background velocities of the two superfluids are transonic, the system is characterized by two distinct acoustic horizons: the hydrodynamic analog of the black hole event horizon. The Hawking-like emission occurring at these horizons produces an effective friction on the fluids. We compute the viscosity-to-entropy ratios close to the two acoustic horizons, finding that the emission of pseudo Nambu-Goldstone bosons violates the bound conjectured by Kovtun, Son, and Starinet.

In this study, we explore a relativistic quantum Otto heat engine with a qutrit as the working substance interacting with a quantum scalar field in curved spacetime. Unlike qubits, which extract work by simply expanding or shrinking a single energy gap, qutrits allow multiple energy gaps to be adjusted independently, enabling more versatile work extraction in the quantum Otto cycle. We derive a general positive work condition in terms of the effective temperature that each pair of energy levels perceives. Moreover, we discuss additional subtleties that are absent when using a qubit, such as the generation of coherence terms in the density matrix due to interactions.

Due to the complexities of the Laser Interferometer Space Antenna (LISA), data gaps arising from instrumental irregularities and/or scheduled maintenance are unavoidable. Focusing on merger-dominated massive black hole binary signals, we test the appropriateness of the Whittle-likelihood on gapped data in a variety of cases. From first principles, we derive the likelihood valid for gapped data in both the time and frequency domains. Cheap-to-evaluate proxies to p-p plots are derived based on a Fisher-based formalism, and verified through Bayesian techniques. Our tools allow us to predict the altered variance in the parameter estimates that arises from noise mismodeling, as well as the information loss represented by the broadening of the posteriors. The result of noise mismodeling with gaps is sensitive to the characteristics of the noise model, with strong low-frequency (red) noise and strong high-frequency (blue) noise giving statistically significant fluctuations in recovered parameters. We demonstrate that the introduction of a tapering window reduces statistical inconsistency errors, at the cost of less precise parameter estimates. We also show that the assumption of independence between intergap segments appears to be a fair approximation even if the dataset is inherently coherent. However, if one instead assumes fictitious correlations in the data stream, when the data segments are actually independent, then the resultant parameter recoveries could be inconsistent with the true parameters. The theoretical and numerical practices that are presented in this work could readily be incorporated into global-fit pipelines operating on gapped data.