The analysis of the latest most accurate experimental data on neutron decay for the possibility of the existence of the right vector boson $W_R$ is carried out. As a result of the analysis within the framework of the left-right symmetric model, it was found that there is an indication of the existence of the right vector boson $W_R$ with a mass of $M_{W_R}={304}_{-20}^{+24}\mathrm{GeV}$, and a mixing angle with $W_L$: $\zeta =-0.039\pm 0.014$. It is shown that this result does not contradict the experiments at colliders to search for a hypothetical vector boson. In addition, it is shown that it is possible to describe the effects of $CP$ violation in decays of neutral $K$-mesons and $D$-mesons using the parameters of the extended left-right symmetric model obtained from neutron decay, i.e., squared masses of the left and right bosons ratio and the mixing angle. The formation of baryon-lepton asymmetry of the Universe is considered within the framework of the left-right model of weak interaction with $CP$ violation.

We investigate the implications of spontaneous $CP$ violation in the general two Higgs doublet model, which leads to a nondecoupling structure of the Higgs sector. All the masses of the Higgs bosons are purely determined by the vacuum expectation value of the Higgs fields, and are thus constrained to be smaller than $\mathcal{O}(500)\mathrm{GeV}$ by the perturbative unitarity bound. Such a nondecoupling nature predicts sizable deviations from the Standard Model expectations in the observables of the discovered Higgs boson ($h$). We find that the magnitude of deviations in ${\mathcal{B}}_{h\to \gamma \gamma }$ (${\mathcal{B}}_{h\to Z\gamma }$) are larger than $\sim 10\%(4\%)$ in the Higgs alignment limit. Moreover, we show that a robust correlation emerges between the deviations in the one-loop corrected $hhh$ coupling and ${\mathcal{B}}_{h\to \gamma \gamma }$ to be, e.g., 200% (50%) and $-10.3\%$ ($-10.8\%$), respectively, under the constraints from theoretical bounds and current experimental data. Using a few benchmark points, we highlight that flavor-violating decays of the additional Higgs bosons can be sizable due to the constrained structure of the Yukawa interactions.

The Froggatt-Nielsen (FN) mechanism offers an elegant explanation for the observed masses and mixings of Standard Model fermions. In this work, we systematically study FN models in the lepton sector, identifying a broad range of charge assignments (“textures”) that naturally yield viable masses and mixings for various neutrino mass generation mechanisms. Using these textures, we consider higher-dimensional operators consistent with a FN origin and find that natural realizations predict distinct patterns in lepton flavor- and number-violating observables. For Dirac and Majorana neutrinos, FN-related correlations can lead to detectable rates of charged lepton flavor violation at next-generation low-energy experiments. Majorana and type-I seesaw models predict measurable rates of neutrinoless double beta decay. Determination of inverted neutrino mass ordering would exclude the Dirac neutrino FN scenario. Only a small minority of purely leptonic FN models predict detectable flavor violation at future muon colliders, though it is possible that a combined analysis with the quark sector will reveal motivated signals. These findings highlight the power of the FN mechanism to link neutrino mass generation to testable leptonic observables, offering new pathways for the experimental exploration of lepton number and underscoring the importance of next-generation low-energy probes.

We propose a new scotogenic type model based on a global $Z_4$ symmetry involving dark matter candidates. After the symmetry breaking as $Z_4$ to $Z_2$ via the singlet scalar vacuum expectation value (VEV), the lightest Majorana fermion works as a viable thermal freeze-out dark matter (DM) candidate, and the mass terms for active neutrinos are generated as a finite quantum correction at the one-loop level. A key point of realizing our scotogenic structure is to introduce two types of Majorana fermions (heavy right-handed neutrinos) and inert Higgs doublets with opposite $Z_4$ parities. Since a large VEV for the singlet scalar is not so harmful in an appropriate realization of the Higgs mechanism for the SM gauge symmetry, we can naturally realize a TeV-scale fermionic DM candidate, where constraints via direct detection experiments are less than those for sub-TeV DM. Our scenario involves the Higgs-portal DM interactions, which help the realization of the correct DM relic abundance. Relying on the structure of the model, it is possible to find a natural partner for coannihilation. Our scenario can be investigated via the measurement of the Higgs trilinear self-coupling at the Large Hadron Collider. The simplest way to evade the domain-wall problem, by adding a tiny soft $Z_2$ breaking term, works, keeping a sufficient longevity of the decaying DM lifetime.

SU(3) gauge theories with an increasing number of light fermions are the templates of strongly interacting sectors and studying their low-energy dynamics and spectrum is important, both for understanding the strong dynamics of QCD itself, and for discovering viable UV completions of beyond the Standard Model physics. In order to contrast many-flavor strongly interacting theories with QCD on a quantitative footing, we use lattice field theory simulations. We focus on the study of the flavor-singlet spectrum in the scalar and pseudoscalar channels: This is an interesting probe of the dynamics of the strongly interacting sector, as reminded by the QCD case with the $f_0(500)$ ($\sigma$) and ${\eta }^{\prime }$ mesons. The hierarchy of the spectrum of a strongly coupled new gauge sector of the Standard Model defines the potential reach of future colliders for new physics discoveries. In addition to a novel hierarchy with light scalars, introducing many light flavors at fixed number of colors can influence the dynamics of the lightest flavor-singlet pseudoscalar. We present a complete lattice study of both of these flavor-singlet channels on high-statistics gauge ensembles generated by the LatKMI Collaboration with 4, 8, and 12 copies of light mass-degenerate fermions. We also present other hadron masses on the lightest ensemble for $N_f=8$ generated by the LatKMI Collaboration and discuss the chiral extrapolation of the spectrum in this particular theory. We contrast the results to $N_f=4$ simulations and previous results of $N_f=12$ simulations.

In this work, we systematically investigate the jet associated identified hadron productions of pions, kaons, and protons based on the event topological separation method in proton-proton ($pp$) collisions at $\sqrt{s}=13\mathrm{TeV}$ employing a multiphase transport model with pythia8 initial conditions. Enabling relative transverse event activity classifier $R_T$, we analyze the transverse momentum ($p_T$) spectra and particle ratios in the jet aligned toward region and the underlying event contributions sensitive transverse region varying with $R_T$. The results indicate that a multi-phase transport model, incorporating both partonic and hadronic final-state interactions, provides a satisfactory description to the experimental data of the $p_T$ differential yields, particle ratios, and average transverse momentum of identified particles in both the toward and transverse regions across different event activity classes. By subtracting the underlying event contribution from the toward region using the transverse region hadron yield, we introduce the in-jet hadron productions to analyze the modifications to the jet itself. We find that the in-jet baryon to meson ratios reveal a sensitive dependence on $R_T$ driven by final-state interactions, leading to a unique crossing pattern at intermediate $p_T$. This behavior can be regarded as a novel signature for probing jet medium interactions and energy loss effects in small collision systems.

In light of the recent measurement of the $\eta \to {\pi }^0\gamma \gamma$ decay by the KLOE-2 Collaboration, a previous analysis including vector- and scalar-meson exchange contributions using the vector meson dominance and linear sigma model frameworks, respectively, is extended in the present study to incorporate the effects of the $a_2(1320)$ tensor meson within a chiral context. Although the individual contribution of the $a_2$ is negligible, its destructive interference with the vector-meson resonances is found to be significant, representing approximately 18% of the total signal and substantially affecting the diphoton invariant-mass distribution, especially at low $m_{\gamma \gamma }^2$ values. The total decay rate is calculated to be $\mathrm{\Gamma }(\eta \to {\pi }^0\gamma \gamma )=0.154(22)\mathrm{eV}$, which corresponds to a branching ratio of $\mathrm{BR}(\eta \to {\pi }^0\gamma \gamma )=1.17(17)\times {10}^{-4}$. This result is approximately $5\sigma$ below the reported value of the particle data group, $2.55(22)\times {10}^{-4}$, while it is in very good agreement with the KLOE-2 measurement, $0.98(11_{\mathrm{stat}})(14_{\mathrm{syst}})\times {10}^{-4}$. In contrast, the total contribution of the $a_2$ is found to be negligible in ${\eta }^{\prime }\to {\pi }^0\gamma \gamma$, as this process is completely dominated by the exchange of an on-shell $\omega$ vector resonance.

The diabatic dynamical diquark model is designed to unify diquark and molecular approaches for exotic hadrons by including the effects of dimeson thresholds on fundamental diquark-antidiquark states in order to form physical tetraquarks. We generalize this model by implementing the consequences of heavy-quark spin symmetry for each dimeson pair. We include the specific spin factors and mass differences associated with mesons related by this symmetry (such as $D,D^{*}$), both features being necessary for the systematic incorporation of effects beyond the static, heavy-source limit inherent to the (adiabatic) Born-Oppenheimer treatment. We obtain explicit interaction potentials for all $J=0$, 1, 2 states, along the way deriving unusual variants of Fierz reordering identities, and discuss the application of the potentials to specific physical states such as ${\chi }_{c1}(3872)$ and $T_{c\overline{c}1}(3900)$.

Inflation and dark energy (DE), both featuring accelerated expansion, are crucial components of modern cosmology. As indicated by singularity theorems, null energy condition (NEC) violation is essential for resolving the initial singularity of inflation. The latest DESI DR2 results show that the DE equation of state evolves from $w_{\mathrm{DE}}<-1$ at redshift $z\lesssim 1$ to $w_{\mathrm{DE}}>-1$ today, reinforcing interest in testing NEC violation in the observable Universe. Within a unified effective field theory framework that applies to both inflation and DE, we use DESI DR2 data and a nonparametric reconstruction approach to test, for the first time, the “beyond Horndeski” physics known to support fully stable NEC violation in nonsingular cosmology. Therefore, our work provides a novel avenue to constrain the physics underlying NEC violation in a model agnostic way. It also highlights the potential relevance of NEC violation to both the primordial Universe and late-time cosmic acceleration.

We consider a recently discovered mathematical correspondence between the spectra of a naively discretized lattice fermion and that of a periodically driven (i.e., Floquet) quantum system and enhance it into an infrared equivalence between the two systems. The equivalence can be framed as a duality relation, allowing us to simulate a two-flavor discrete-time fermion theory on the lattice side, where the two flavors arise from time discretization, using a single-flavor fermion theory on the Floquet side. Our demonstration establishes an equivalence between (i) the fermion content, (ii) the correlation functions, and consequently (iii) observables of the two theories in the infrared, going substantially beyond the previously discovered spectral equivalence. We also show how interactions may be incorporated into this enhanced infrared equivalence.

We present the most precise results for the ground state mass of the triply-charmed spin-$3/2$ baryon using lattice quantum chromodynamics. The calculations are performed on six $N_f=2+1+1$ highly improved staggered quark (HISQ) lattice ensembles generated by the MILC collaboration. Two different lattice setups are employed: in the first one, a fully dynamical calculation with HISQ action is performed, while in the second calculation, an overlap action is utilized for the valence charm quark dynamics. Following the continuum extrapolation of our results, obtained at five different lattice spacings, two different volumes, and two different actions, our prediction for the mass of the lowest triply charmed spin-$3/2$ baryon, ${\mathrm{\Omega }}_{ccc}(3/2^{+})$, is $4793(5){(}_{-8}^{+11})\mathrm{MeV}$. This is the most precise determination to date, fully addressing the systematic uncertainties. We also predict the ${\mathrm{\Omega }}_{ccc}(3/2^{-})$ mass to be $5094(12){(}_{-17}^{+19})\mathrm{MeV}$.

We present a comprehensive QCD analysis of the $B\to \pi \pi$ form factors within the framework of light-cone sum rules, employing two-pion light-cone distribution amplitudes ($2\pi \mathrm{DA}$s). For the first time, we derive the twist-three $2\pi \mathrm{DA}$s explicitly by exploiting the conformal symmetry of massless QCD. This breakthrough enables the first systematic calculation of higher-power corrections to the $B\to \pi \pi$-type transitions. Leveraging the recently measured partial decay fractions of $B^{+}\to {\pi }^{+}{\pi }^{-}{l}^{+}{\nu }_l$ by the Belle detector, we obtain $|V_{ub}|=(4.27\pm 0.49{|}_{\mathrm{data}}\pm 0.55{|}_{\text{LCSRs}})\times {10}^{-3}$ within the dominant region of the $\rho$ resonance. We clarify that the relatively small value of $|V_{ub}|$ extracted from $B\to \rho l\nu$, when compared to the golden channel $B\to \pi l\nu$, arises due to the finite width and nonresonant effects. We anticipate future measurements of purely isovector and isoscalar $B_{l4}$ decays, which will aid in reducing uncertainties by enhancing our understanding of the $\pi \pi$ phase shifts in the two-pion distribution amplitudes through heavy flavor decays.

We discuss confinement and chiral symmetry breaking in $\mathrm{SU}(N_c)$ gauge theories with fermions in the adjoint representation. There has been considerable work on studying these theories compactified on a small circle (with compactification scale $1/L$ large relative to the strong coupling scale of the theory). The weakly coupled IR theory of photons exhibits confinement through a density of magnetically charged instanton configurations. As the compactification scale $1/L$ approaches the strong coupling scale, the IR theory becomes strongly coupled. In this regime we propose a holographic description of the IR degrees of freedom. The instanton condensation scale can be associated with a scale at which the Brietenlohner-Freedman (BF) bound is violated in the model and the glueball spectrum is computed. We can also introduce the adjoint fermions which holographically display a BF bound violation associated with their running anomalous dimension. Very naively extending the perturbative results to the nonperturbative regime suggests that chiral symmetry breaking might occur ahead of confinement, but equally they may be joined phenomena. If the two phenomena are separate, then it would be useful to be able to enlarge the gap in scales. We propose adding fermions in the fundamental representation as well, which in a holographic model (that favors this separation) can greatly enlarge the gap to an order of magnitude. These results challenge the lattice community to seek such scale gaps (or their absence) to further understand the confining and chiral symmetry breaking dynamics.

We argue that a discrete bulk spectrum with random statistics appears naturally in the Lorentzian description of Jackiw-Teitelboim (JT) gravity if an extra confining potential is introduced in the region where the renormalized geodesic length becomes of order $e^{S_0}$. The existence of such an extra confining potential may be inferred from the late behavior of complexity and also from the Saad-Shenker-Stanford (SSS) duality between JT gravity and the matrix model. We derive the explicit form of the extra confining potential from the well-established density of states obtained in the Euclidean approach to JT gravity. This extra potential is implicitly determined by the solution of the Abel’s integral equation, which turns out to be identical to the string equation of the matrix model in the SSS duality formulation of JT gravity. Thanks to the extra confining potential and the random nature of the spectrum, the time evolution of the Krylov complexity, which is identified with the renormalized geodesic length, naturally exhibits four phases, namely, a ramp, a peak, a slope, and a plateau.

While black hole and neutron star mergers are the most plausible sources of current gravitational-wave observations, mergers of exotic compact objects may mimic these signals. Proca stars—Bose-Einstein condensates of complex vector ultralight bosons—have gained significant attention for their potential to replicate certain gravitational-wave events while yielding consistent estimates of the boson mass ${\mu }_B$ forming the stars. Using a mixture model within a Bayesian framework, we demonstrate that consistent boson mass estimates across events can be exploited to obtain conclusive evidence for the existence of a number $n$ of Proca-star families characterized by respective boson masses ${\mu }_B^i$, even if no individual event can be conclusively identified as such. Our method provides posterior distributions for $n$ and ${\mu }_B^i$. Applying this framework to the high-mass events GW190521, GW190426_190642, and GW200220_061928, we obtain a Bayes factor ${\mathcal{B}}_{n=1}^{n=0}=2$ against the Proca-star hypothesis, primarily rooted in the limitation of current Proca-star merger signal models to intrinsically weak head-on cases. We show that conclusive evidence $\log {\mathcal{B}}_{n=0}^{n=1}\ge 5$ could be achieved after five to nine observations of similar event sets, at the 90% credible level. Our framework provides a new way to detect exotic compact objects, somewhat using gravitational-wave detectors as particle detectors.

The scale-free nature of gravitational interaction in both Newtonian gravity and the general theory of relativity gives rise to the concept of self-similarity, where solutions are scale invariant. As a result of this property, the governing partial differential equations are greatly simplified and can be transformed into ordinary ones. These solutions function as attractors, characterizing the asymptotic dynamics of more general solutions. There exist situations in which self-similarity is only partially realized, giving rise to kinematic self-similar solutions. Our study provides a systematic classification of kinematic self-similar solutions corresponding to the most general spherically symmetric spacetime in the presence of bulk viscous flows.

The universality of free fall is one of the most cherished principles in classical gravity. Its fate in the quantum world is one of the key questions in fundamental physics. We investigate the universality of free fall in the context of Planck scale modifications of Newtonian gravity. Starting from a doubly-special-relativity setting we take the Newtonian limit to obtain deformed Galilean relativity. We study the interaction between two test particles, subject to deformed Galilean relativity, and a classical, undeformed gravitational source, the Earth. Such an interaction is investigated here for the first time. Considering the two test particles falling freely in the source’s gravitational field, we examine whether the universality of free fall is affected by deformed relativistic symmetries. We show that, in general, the universality of free fall is violated. Remarkably, we find that there exist distinguished models for which the universality of free fall is realized and which predict a specific modification of the Newtonian potential.

In many fields including cosmology, statistical inference often relies on Gaussian likelihoods whose covariance matrices are estimated from a finite number of simulations. This finite-sample estimation introduces noise into the covariance, which propagates to parameter estimates, a phenomenon known as the Dodelson-Schneider (DS) effect, leading to inflated uncertainties. While the Massively optimized parameter estimation and data compression (MOPED) algorithm offers lossless Fisher information-preserving compression, it does not mitigate the DS effect when the compression matrix itself is derived from noisy covariances. In this paper, we propose a modified compression scheme, powered MOPED ($p$-MOPED), which suppresses noise propagation by balancing information retention and covariance estimate noise reduction through a tunable power-law transformation of the sample correlation matrix. We test $p$-MOPED against standard and diagonal MOPED on toy models and on cosmological data from the Subaru Hyper Suprime-Cam Year 3 weak lensing survey. Our results demonstrate that $p$-MOPED consistently outperforms other approaches, especially in regimes with limited simulations, offering a robust compression strategy for high-dimensional data analyses under practical constraints.

Applying the light-cone sum rules approach, the next-to-leading-order corrections to $B\to A$ form factors are calculated with the twist-two and twist-three $B$-meson light-cone distribution amplitudes (LCDAs) at leading power in $\mathrm{\Lambda }/m_b$. At one-loop level, the vacuum-to-$B$-meson correlation functions defined with interpolating currents for the $p$-wave axial-vector meson are factorized into short-distance coefficients and the distribution amplitudes of the $B$ meson, among which the hard coefficients for A0-type currents and $\mu$-dependent jet functions entering correlation functions ${\mathrm{\Pi }}_{\mu ,\parallel }^{(T+\tilde{T})}$, ${\mathrm{\Pi }}_{\delta \mu ,\perp }^{(V-A)}$, and ${\mathrm{\Pi }}_{\delta \mu ,\perp }^{(T+\tilde{T})}$ are identical to the corresponding ones of $B\to V$ in soft-collinear effective theory (SCET). In addition, ${\mathrm{\Pi }}_{\mu ,\parallel }^{(V-A)}$ and ${\mathrm{\Pi }}_{\mu ,\parallel }^{(T+\tilde{T})}$ coincide with the results of $B\to \pi ,K$ under the limit $m_q\to 0$ up to one-loop accuracy. Then the subleading-power corrections to $B\to A$ form factors are computed with the higher-twist $B$-meson LCDAs at tree level up to the twist-six accuracy. Furthermore, we predict the $q^2$ dependence of $B\to A$ form factors via the Bourrely-Caprini-Lellouch $z$-series expanding parametrization to compute several physical observables including branching ratios of semileptonic $B\to A\ell {\overline{\nu }}_{\ell }$ and $B\to A{\nu }_{\ell }{\overline{\nu }}_{\ell }$ processes, transverse asymmetries, forward-backward asymmetries, and lepton-flavor universality observables employing the given mixing angles ${\theta }_K=-34°$, ${\theta }_{1_{P_1}}=28°$, and ${\theta }_{3_{P_1}}=23°$. We also compare our theory calculations with the results from other methods.