We perform an analysis of LQCD light - charmed (pseudoscalar) meson scattering data with UChPT for pion masses ranging from $m_π\simeq 230$~MeV till the SU(3) limit, $m_π\simeq 700$~MeV. We find two poles in the non-strange isospin $I=1/2$ sector that can be related to the experimental $D_0(2300)$ resonance. At the physical pion mass, the poles are located at $\sqrt{s_0}=2094(7)(1)-i111(7)(13)$ MeV, and $2463(60)(30)-i108(14)(12)$~MeV. While the first pole, named here $D_0^*(2100)$, is always a resonance in $Dπ$ within the $1σ$ region, the second pole can be a resonance or virtual state close to the $Dη, D_s\bar{K}$ thresholds. For the first time, the pion mass dependence on different chiral trajectories including SU(3) LQCD data are investigated for these poles. We find that in the $m_s=m_{s,\mathrm{phy}}$ trajectory, the $D_0^*(2100)$ resonance pole behaves similarly as the $σ$ resonance in $ππ$ scattering, splitting into two poles, connected to the $\bar{\mathbf{3}}$ representation. Moreover, we found that the higher pole related to the experimental $D_0^*(2300)$ can be related to the $\mathbf{6}$ representation. We highlight that since this pole couples strongly to channels with hidden strangeness, its mass is fairly constant in the $\mathrm{Tr}[M]=C$ trajectory, what can be tested in future LQCD simulations. The compositeness of the $D_0^*(2100)$ state at the SU(3) limit is evaluated. Finally, other sectors are also discussed.

Right-handed lepton flavor mixing in the left-right symmetric model directly affects the production and decay of heavy Majorana neutrinos $N_R$, yet its impact on collider searches remains less explored. Using a deep neural network (DNN), we analyze the Keung-Senjanović process $pp \to W_R \to \ell_αN_R \to \ell_α\ell_βjj$ with $\ell_{α,β}=e,μ$ at LHC Run~2 and the HL-LHC, considering both same-sign and opposite-sign dilepton channels. We adopt three benchmark mixing scenarios: unmixed, maximal-mixing, and PMNS-like. In the unmixed scenario, the DNN improves the expected significance over the cut-based analyses performed by ATLAS, leading to stronger exclusion limits. For the combined $\ell\ell$ analysis, the HL-LHC can exclude $m_{W_R}$ and $m_{N_R}$ up to $6.7$ ($6.3$)~TeV and $4.4$ ($4.1$)~TeV, respectively, under maximal (PMNS-like) mixing. LHC Run~2 already excludes a significant portion of the $|V_{e1}|\text{--}|V_{\mu1}|$ plane, and the HL-LHC will probe even smaller mixing values, possibly ruling out both the maximal and PMNS-like patterns. Finally, we investigate complementarities with low-energy charged lepton flavor violation processes, where future searches can overlap with or exceed the LHC reach.

In this contribution to the Encyclopedia of Nuclear Physics, we aim to provide a pedagogical introduction to the functional approach to QCD at finite temperature and chemical potential. We briefly outline the general framework and address its complementarity to other first-principle approaches to non-perturbative QCD. We discuss selected results obtained with Dyson-Schwinger equations (DSE) and the functional renormalisation group (fRG) in the context of a general physics perspective on the QCD phase diagram. This article is specifically aimed at students and non-practitioners of functional methods alike and may serve as a short guide to further literature.

The chiral anomaly famously manifests in a rich variety of forms, from abelian and singlet to consistent or covariant. In this paper, all these realizations are described in detail, along with their properties and phenomenological applications. Central to this presentation is a novel expression for the fully generic chiral anomaly, derived with either massive or massless fermions, that incorporates not only the standard triangle but also the box and pentagon diagrams. From this master expression, the various traditional forms of the anomaly are then transparently derived. This provides a powerful tool, technically and conceptually, driving two further objectives. First, the topological aspects of each form are dutifully described while bypassing the differential language entirely, save for Stokes' theorem. Second, to make sure anyone interested can truly reproduce all the results in a reasonable amount of time, a FeynCalc implementation of the relevant calculations is provided. Ultimately, this simplified and unified description of all the forms of the chiral anomaly highlights the underlying conceptual beauty, and offers a comprehensive grasp of the physics at play.

Recent work has proposed sequential hadronization of open-charm hadrons in the quark-gluon plasma, wherein more tightly bound species such as $D_s^+$ form earlier near $1.2 T_c$ and $D^0$ forms later at $T_c$. That work showed that this mechanism naturally reverses the sign of the $D^0-D_s^+$ elliptic-flow splitting relative to the conventional simultaneous baseline. In this work, we demonstrate that event-shape engineering (ESE) provides a sharper discrimination between the two pictures than inclusive measurements alone. By selecting large-$q_2$ and small-$q_2$ events in 0--10\% and 30--50\% centrality classes in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, we show that the geometry-driven enhancement of charm-meson $v_2$ can be separated from the hadronization-time response: the positive $Δv_2(D^0-D_s^+)$ in the sequential scenario grows systematically with $q_2$, while the corresponding response slope $χ$ reveals a species-dependent hierarchy $χ(D^0) > χ(D_s^+)$ that is robust against the overall flow normalization and absent in the simultaneous baseline. In the simultaneous case, the splitting is near zero or negative and does not follow the same geometry scaling. Notably, the semi-central 30--50\% class emerges as the optimal window, because the non-monotonic interplay between QGP lifetime and initial eccentricity maximizes the late-stage flow conversion. The $q_2$ ratios of the $D_s^+/D^0$ yield ratio remain close to unity, confirming that the splitting is a dynamical flow effect rather than a chemical yield modification. These results establish $Δv_2(D^0-D_s^+)$ and the response slope $χ$ under ESE as complementary differential probes of the space-time structure of charm hadronization near the QCD transition temperature.

We study constraints on sub-GeV inelastic dark matter (iDM) from cosmic-ray (CR) cooling in the active galactic nucleus (AGN) NGC 1068. In dense dark matter (DM) spikes surrounding supermassive black holes, high-energy CR protons can efficiently lose energy through scatterings with dark matter particles. We consider a minimal vector-portal iDM framework and consistently include both elastic and deep inelastic scattering (DIS) contributions to the CR energy-loss rate. We find that DIS processes dominate at high momentum transfer and substantially enhance the DM-induced cooling effect. By requiring the resulting cooling timescale to remain compatible with the observed Standard Model cooling in NGC 1068, we derive constraints on the iDM parameter space. Our results demonstrate that AGN cosmic-ray cooling probes previously unexplored regions of sub-GeV iDM parameter space inaccessible to current direct-detection experiments.

Ultralight dark matter (ULDM) coupled to the Standard Model may effectively induce coherent oscillations of fundamental constants and thereby generate narrow-band signals in precision interferometric experiments. Here we present a systematic study of how these oscillations leave distinctive imprints on space-based laser interferometers, including LISA and Taiji. Starting from the one-way inter-spacecraft link observables, we analyze several instrument-level effects induced by ULDM, including composition-dependent acceleration of test masses, laser-frequency variations associated with cavity-length modulation, refractive-index effects, and clock-related contributions. We then propagate these signals through the standard data processing chain, including time-delay interferometry and clock-noise elimination. We show that the observability of an ULDM-induced effect is determined by the structure of its single-link response. In particular, the ULDM-driven variation in laser frequency appears in the raw link observable with the same form as laser phase noise. As a consequence, it is strongly suppressed in the final interferometry channels. In contrast, signals that possess an explicit directional pattern are not eliminated by this procedure, such as the ULDM-induced oscillations of the test masses. We further construct a local observable that isolates the differential motion between the test mass and the optical bench, and derive its sensitivity to both the dilaton--gluon coupling $d_g$ and the dilaton--electron coupling $d_e$ for LISA, Taiji, and BBO. We find that the local observable yields sensitivities comparable to the standard Michelson interferometer for $d_g$, but better than Michelson channel by three orders of magnitude for $d_e$.

Neutrino oscillation experiments provide a unique probe to search for the physics beyond the Standard Model. In this work, we search for a broad class of anomaly-free flavor-dependent $U(1)^\prime$ symmetries using atmospheric neutrino data for the first time. Gauging these $U(1)^\prime$ symmetries give rise to ultra-light vector gauge bosons mediating long-range interactions (LRI) of neutrinos. These new interactions are sourced by the matter present in local and distant Universe, which can affect oscillations of neutrinos passing through the Earth. We use 8 years of high-purity $ν_μ$ charged-current neutrino events from IceCube DeepCore to search for these new interactions. We find no evidence for such new interactions in the data sample and place stringent constraints on the corresponding LRI potentials. These results are also translated as the bounds on the coupling strength and mass of mediator over their wide ranges for a plethora of $U(1)^\prime$ symmetries.

We report phase shift measurements of neutron matter waves propagating in vacuum and low-pressure Argon gas, using a technique developed for neutron interferometric scattering length measurements. The experiment probes additional phase shifts induced by couplings to scalar fields. From the absence of such effects, we set stringent constraints on a scalar symmetron-field, a leading candidate for quintessence dark energy.

We investigate the production of the $Δ(1232)^{++}$ resonance in the charmed baryon weak decay $Λ^+_c \to K^- π^+ p$, focusing on the $π^+ p$ final-state rescattering mechanism. The direct $W^+$ exchange diagram is expected to be suppressed, hence we adopt the $W^+$ internal emission process $Λ^+_c \to p \bar K^{*0}(892)$ followed by the subsequent decay $\bar{K}^{*0} \to K^- π^+$ as the dominant source of the final state particles. The $Δ(1232)^{++}$ resonance is then generated via $π^+ p$ rescattering within a triangle loop mechanism. Our calculations incorporate both the tree-level $\bar K^{*0}(892)$ and the dynamically generated $\bar{K}^*_0(700)$ state arising from the $S$-wave $K π$ final state interaction. We find that our theoretical results can reproduce the bump and peak structures in the $K^- π^+$ invariant mass distributions for the $\bar{K}^*_0(700)$ and $\bar{K}^{*0}(892)$, respectively. Meanwhile, the peak for the $Δ(1232)^{++}$ in the $π^+ p$ invariant mass distributions is also well described. The $Δ(1232)^{++}$ signal naturally emerges from rescattering effects, and adopting the pole parameters of $Δ(1232)$ resonance yields an improved description of the experimental data. In addition, we obtain a branching fraction ratio $\mathcal{B}[Λ_c^+ \to Δ(1232)^{++} K^-] / \mathcal{B}[Λ_c^+ \to p \bar{K}^{*0}(892)] \approx 0.5$, which is lower than the experimentally measured value. This discrepancy suggests that interference effects are likely significant in this decay process. Future high-precision measurements will further verify the proposed rescattering mechanism.

Light dark matter (DM) (mass $\lesssim \mathcal{O}(100)$ keV) remains challenging to detect in several ongoing indirect detection experiments due to threshold limitations. Recent observations of diffuse X-ray photons from the NuSTAR stray-light (SL) data provide a powerful avenue to probe such light DM through its decay signatures in the galactic halo. This work explores the indirect detection prospects of decaying electrophilic scalar DM, electrophilic and photophilic ALP DM, and dark photon DM using the recent NuSTAR SL data. We find that for DM scenarios producing monochromatic two-photon signals, NuSTAR SL data can yield the strongest indirect detection bound in the $\sim6-36$ keV mass range. In contrast, for dark photon (vector) DM featuring a continuous three-photon spectrum, the strongest indirect detection upper bound arises in the $\sim 20-70$ keV mass range. Additionally, we discuss the detection prospects of inelastic DM where the heavier DM decays to a two or three-photon final state along with a massive lighter dark sector particle. By comparing the resulting continuous photon spectra with the NuSTAR SL data, we obtain the most stringent upper bound on the lifetime of such DM for the mass splitting $Δm$ in the range $3 ~{\rm keV}- 100$ keV.

The study of fully light tetraquark states composed solely of the light quarks u, d, and s provides an essential framework to understand the underlying dynamics of low-energy Quantum Chromodynamics (QCD). Within the framework of SU(3)f flavor symmetry, these states are classified into different multiplets, giving rise to a rich spectrum of non-strange, singly strange, doubly strange, and hidden-strangeness configurations.

To study charm -quark pair production processes, we utilized the color dipole picture gluon distribution function in a collinear generalized double asymptotic scaling approach at small Bjorken $x$ values ($x{\leq}10^{-2}$). Our results show good agreement with the latest HERA experimental data for reduced cross sections $σ_{\mathrm{red}}^{c\overline{c}} (W^2,Q^2)$ across a wide range of $x$ and $Q^2$ values, yielding an effective pomeron intercept. A Hard pomeron intercept with the coefficient $C_{2}=0.29$ in the color dipole model provides comparable results at very low $x$ values ($x{<}10^{-3}$). We demonstrate that the experimental data from HERA in the region $2.5{\leq}Q^2{\leq}2000~\mathrm{GeV}^2$ confirms the symmetry between the saturation and color transparency regions in the scaling variable $η$, shifting towards the color transparency region when we incorporate the threshold mass production of $J/ψ$ meson in the color dipole picture.

The impact of higher-twist corrections to the ratio $\frac{σ_{r}}{F_{2}}(A,Q^2/s,Q^2)$ for light and heavy nuclei is considered at fixed a $\sqrt{s}$ and $Q^2$ to the minimum value of $x$ given by $Q^2/s$. The results are for the EIC center-of-mass energies. We apply the influence of higher-twist corrections to $\frac{σ_{r}}{F_{2}}(A,Q^2/s,Q^2)$ by the dimensionless variable $ξ'_{A}=Q_{s,A}^{2}/Q^2$ in the color dipole model and obtain bounds for the ratio in the linear region. The importance of contributing to twist-4 at small-$x$ is visible in the linear region where $ξ'_{A}{\leq}1$. We perform that twist-4 corrections of the saturation model are shown the successful behavior of $\frac{F_{L}}{F_{2}}(A=2,x,Q^2)$ in comparison with the JLab data at $ξ'_{A}{\leq}1$. The higher-twist corrections due to twist-6 and twist-8 are resummed by the non-linear approaches in the region $ξ'_{A}>1$. The ratio $\frac{F_{L}}{F_{2}}$ deuteron is considered in the low-$Q^2$ and small-$x$ region and compared with the JLab data which takes into account the non-linear corrections due to twist-6 and twist-8. A comparison with the JLab data shows that the impact of the distinct twists allows us to probe the presence of non-linear effects on the QCD dynamics as $F_{L}{\rightarrow}0$ and the polarization of the virtual photon is transverse in this region.

We study the predictions of saturation effects in electron-ion colliders at high inelasticity, using a generalization for nuclear targets of the ASW and GBW models where the saturation scale, $Q_{\mathrm{sat}}$, drives the energy dependence and the corresponding nuclear effects. We expect to observe an enhancement of the ratio of nuclear reduced cross sections in the saturation region in future electron-ion colliders. The ratio $R^{A}_{σ_{r}}$ is discussed in the kinematic range of the electron-Ion collider with center-of-mass energy $\sqrt{s}=89~\mathrm{GeV}$ at high inelasticity $y{=}1$. The importance of the nuclear longitudinal structure function $F^{A}_{L}$ in the ratio $R^{A}_{σ_{r}}$ for the heavy nucleus lead and light nucleus deuteron at $x_{\mathrm{min}}=Q^2/s$ is discussed. This enhancement in the range $Q^2\sim(1-4~\mathrm{GeV}^2)$ in the ratio $R^{A}_{σ_{r}}$ is not observed in the ratio $R^{A}_{F_{2}}$ which is comparable with the nuclear ratio of the nuclear parton distribution functions. We demonstrate that the study of nuclear charm structure function allows us to estimate the magnitude of shadowing effects in high inelasticity in the nuclear gluon distribution.

The chiral quark soliton model (CQSM) is an effective quark model of baryons maximally taking account of the most important feature of low-energy QCD, i.e., the spontaneous chiral symmetry breaking of the QCD vacuum and the associated appearance of Nambu--Goldstone pions. It shares many common features with the famous Skyrme model in that the baryons are viewed as rotating hedgehog objects in both models. Despite many similarities, it turned out that the CQSM can give more realistic predictions on most baryon observables. Above all, a decisive advantage of the CQSM over the Skyrme-like models is that it can handle non-local quark--quark correlations in baryons, which is absolutely impossible within the framework of effective meson theories. This feature is decisively important for making theoretical predictions on the quark distribution functions inside the nucleon, which are defined as nucleon matrix elements of bilinear quark operators with light-cone separation. In the present paper, we try to elucidate why and how the CQSM can give successful predictions for a variety of types of nucleon quark distribution functions, especially for the flavor asymmetry of the unpolarized and longitudinally polarized sea-quark (anti-quark) distribution functions in the nucleon.

In the context of grand unified theories, any cosmic strings present in the post-inflationary universe are likely to be metastable, with a decay rate set by the spontaneous creation of monopole pairs on the string. Determining this decay rate is crucial in understanding the phenomenology of the cosmic string network, including a potentially observable gravitational wave background. The bounce action governing this rate has so far only been determined using the thin string approximation or specific ansätze for the field profiles in the monopole formation process. Here we solve this problem using classical lattice simulations, relying only on the inherent symmetries of the problem. Our results indicate a suppression of the bounce action and hence a faster string decay compared to previous estimates.

Dark matter particles can be accelerated by annihilation processes such as semi-annihilations and $n \to m$ ($n > m$) processes when the dark sector is non-minimally extended. Such boosted dark matter can provide a distinctive signature of a non-minimal dark sector, and its experimental detectability has been explored in a model-independent manner in previous work. In this work, we construct an explicit model of boosted dark matter originating from semi-annihilations. A Dirac fermion is identified as the dark matter candidate, which semi-annihilates into a pair of an anti-dark matter particle and a neutrino. The small neutrino masses are also radiatively generated at the two-loop level. Taking into account the relevant experimental and theoretical constraints, we find that the mass of the mediator needs to be $\mathcal{O}(1)~\mathrm{MeV}$ for the elastic scattering with protons, so that the cross section is enhanced to $\mathcal{O}(10^{-36})~\mathrm{cm}^2$, allowing detection in future experiments such as DUNE and DARWIN.

We introduce IterInt, a novel package implemented in both Mathematica and C++ for the numerical evaluation of iterated integrals involving arbitrary integration kernels. After the user has defined the integration kernels, IterInt transforms the iterated integrals into a system of first-order linear differential equations which can be solved efficiently and with high precision using well established libraries. IterInt is also able to automatically perform shuffle-regularisation. This makes it possible to evaluate also integrals where the integrand has a pole at the starting point of the integration path. As an illustration of our code, and also to validate it and gauge its performance, we compare the output of IterInt to the results obtained by GiNaC for ordinary and elliptic multiple polylogarithms, and also to existing results for the first few orders for banana integrals with up to four loops.

We present a four-dimensional deconstruction of the extra-dimensional axion arising from a $U(1)$ gauge theory in a five-dimensional orbifold, where the axion is identified with the Wilson line of the $U(1)$ gauge field and its coupling to QCD is generated by a 5D Chern-Simons (CS) term. We construct the corresponding 4D moose (quiver) gauge theory with link scalar fields, in which the axion emerges as a collective pseudo-Nambu-Goldstone boson. The axion-gluon coupling is described by a gauged Wess-Zumino-Witten term, providing the 4D counterpart of the 5D CS term. We further analyze non-perturbative effects from zero-mode and ``fractional'' instanton configurations. While the latter is exponentially suppressed in the regime corresponding to the 5D description, ensuring consistency with the higher-dimensional picture, we point out that this suppression can break down for smaller instantons whose inverse size exceeds the 5D cutoff scale, leading to a potentially significant effect. We also study axion potentials induced by bulk matter fields and boundary-localized symmetry-breaking operators, reproducing the characteristic nonlocal suppression associated with propagation in the extra dimension. Our construction provides a renormalizable 4D framework with a transparent understanding of the axion shift symmetry and its quality.

We investigate how a strong magnetic field generated in noncentral heavy-ion collisions may modify the bottom-up equilibration scenario. In the conventional weak-coupling picture, the earliest stages of the evolution are dominated by overoccupied gluons, while quark production is parametrically delayed. In a background magnetic field, however, additional inelastic channels become kinematically allowed or enhanced, most notably gluon decay into quark-antiquark pairs, $g\to q+\bar q$. Using parametric estimates, we show that for sufficiently strong fields, with $|eB|$ approaching the saturation scale squared, $Q_s^2$, magnetic-field-induced quark production can become important during the earliest stages of bottom-up evolution. This mechanism can populate the hard quark sector, modify the chemical composition of the pre-equilibrium matter, and provide an additional pathway toward chemical equilibration. We also discuss possible back-reaction effects, including quark-antiquark annihilation, depletion of the hard-gluon sector, and the potential feedback of early quark production on the electromagnetic conductivity of the medium. This exploratory study of a magnetically assisted bottom-up scenario provides a natural extension of the standard framework, with qualitative predictions that depend sensitively on the lifetime and spacetime profile of the magnetic field.

We present the next-to-next-to-leading logarithmic (NNLL) collinear resummation of projected $N$-point energy correlators (ENCs) up to $N=6$, matched to fixed-order predictions at NLO, in both electron-positron annihilation and Higgs decay to gluons. The key new ingredient is the two-loop jet function for $N=4,5,6$, which we compute semi-analytically using Integration-by-Parts and differential equations. We further include the leading non-perturbative corrections for ENCs, described by two universal soft matrix elements $\overlineΩ_{1q},\overlineΩ_{1g}$ of order $Λ_{\rm QCD}$, whose evolution is governed by anomalous dimensions for $(N-1)$-point correlators. The matched distributions are compared with parton-shower simulations from Pythia8 and Herwig7, and we study the sensitivity of both the absolute spectra and their ratios to the two-point energy correlator under variations of $α_s$ and $\overlineΩ_{1q,1g}$. Our results show that higher-point projected energy correlators are now under quantitative control at NNLL accuracy, opening the door to future $α_s$ extractions with complementary systematics.

Two Higgs doublets models with a scalar potential that breaks electroweak symmetry spontaneously can have either one or two local minima. While potentials with one minimum can have a decoupling regime where all the new scalars are heavy, we show that, for potentials with $two$ local minima, the masses of all the scalars are bounded if the dimensionless quartic couplings obey perturbativity constraints.

We investigate the low-energy phenomenology of a minimal flavor-deconstructed framework in the lepton sector within an effective field theory approach, focusing on the interplay between flavor and CP violation. Starting from the ultraviolet completion of the model, we derive the effective Yukawa structure through a systematic spurion expansion beyond leading order and identify the dominant sources of flavor and CP violation. We show that, while leading-order effects to dipole operators are approximately aligned with the Yukawa matrices, next-to-leading order contributions generically induce physical CP-violating phases and flavor misalignment, leading to potentially observable low-energy signals. After constructing the corresponding low-energy effective theory, we analyze the phenomenological implications for charged lepton flavor violating observables, lepton flavor universality tests, and electric dipole moments (EDMs). We find that future searches for $μ-e$ conversion and the electron EDM can probe scales in the multi-10~TeV range under natural assumptions on the flavor structure and CP phases. Our results highlight the complementarity between flavor-violating and CP-violating observables and demonstrate that precision measurements in the lepton sector provide a powerful probe of flavor-deconstructed scenarios beyond the direct reach of collider experiments.

We study the cosmology and observational probes of majoron dark matter in a high-scale seesaw framework with spontaneously broken lepton number. Right-handed neutrinos naturally generate light neutrino masses and can realize thermal leptogenesis, while the associated majoron is a light pseudo-Nambu-Goldstone boson that can be cosmologically stable and serve as a viable dark matter candidate for sub-MeV masses. We analyze both pre-inflationary and post-inflationary histories of lepton number breaking. In the pre-inflationary scenario, majoron dark matter is produced by misalignment and constrained by CMB isocurvature. In the post-inflationary scenario, the majoron abundance receives nonthermal contributions from spatially averaged misalignment, majoron radiation from global cosmic strings, and the collapse of the string-domain wall network, as well as a thermally produced component. This scenario can also be probed by future searches for the stochastic gravitational wave background produced by cosmic strings. We map the viable majoron dark matter parameter space and examine complementary probes from X-ray and soft gamma ray searches for majoron decays to photons, black hole superradiance, and Lyman-$α$ forest observations. These results demonstrate that majoron dark matter offers a distinctive cosmological probe of high-scale lepton number breaking and thermal leptogenesis.

Strong self-interaction among the active neutrinos mediated by a neutrinophilic scalar is a well-motivated target of particle physics and cosmological probes. In this article, we present precision electroweak constraints on models for neutrino self-interaction. We first work in the simplified model where the finite radiative corrections are obtained with the guidance of gauge invariance. These corrections are logarithmically enhanced for small mediator masses. We point out the importance of neutrino charged-current coupling correction and its impact on the $Δr$ parameter and Fermi constant measurements. This effect was overlooked previously and allows us to derive the leading constraint on the neutrinophilic couplings for mediator mass above a few hundred MeV. We investigate the robustness of the result in a concrete UV completion which further includes a TeV-scale $SU(2)_L$ triplet scalar and find the simplified model constraints continue to hold for a wide range of parameter space. We pin down moving parts in the UV complete model and conditions when the contributions from heavy particle loops are no longer negligible. Our results serve as a useful road map for future explorations of the self-interacting neutrino paradigm.

We study the stochastic dynamics of heavy quarks propagating through the strongly coupled plasma of $\mathcal{N}=4$ supersymmetric Yang-Mills (SYM) theory at nonzero temperature in terms of the corresponding Kolmogorov equation, which correctly describes their kinetic equilibration and the non-Gaussian fluctuations in their momenta without having to restrict their velocity to the non-relativistic regime. Leveraging the heavy quark limit, we show that the evolution of the momentum space distribution function can be reformulated as a Hamilton-Jacobi problem, and therefore can be solved in terms of first-order ordinary differential equations. We solve these evolution equations in an infinite thermal plasma with a constant temperature for initial conditions specified by spherically symmetric heavy quark momentum distributions with a phenomenologically motivated shape that is steeply falling at large momentum. To highlight the distinctive features of the kinetic equilibration process, we compare their solutions with Fokker-Planck dynamics with the same drag coefficient and fluctuations chosen by hand to guarantee equilibration. We find qualitatively similar dynamics at small momentum, and very different dynamics at large momentum, where, much like in jet quenching phenomena, the steepness of the momentum distribution gives a larger relevance to unlikely events in which a heavy quark loses little momentum in a given time step. Such events are much less unlikely in the Kolmogorov evolution than in Fokker-Planck evolution with the same mean energy loss, meaning that equilibration at large momentum is significantly delayed. Our results provide a systematic description of heavy quarks propagating through strongly coupled plasma from the ultra-relativistic to the non-relativistic regime and point the way towards implementation in phenomenological studies.

Metastable cosmic strings provide a cosmological interpretation of the nanohertz stochastic gravitational wave background reported by Pulsar Timing Array (PTA) experiments. We revisit this scenario in a minimal dark-sector gauge theory, in which a complex Higgs doublet breaks $\mathrm{SU}(2)\times\mathrm{U}(1)\to\mathrm{U}(1)$ at a single symmetry-breaking scale. This one-scale setup predicts metastable $Z$-strings whose endpoints are monopole-like defects, and whose zero-temperature decay rate is controlled by the gauge couplings and mass ratios. We show that, once the string-forming transition occurs in a thermal plasma, the dominant decay channel is not the zero-temperature monopole nucleation but thermally induced nucleation on the string worldsheet. We determine the nucleation temperature, $T_{\rm nuc}$, from the one-loop finite-temperature effective potential with daisy resummation, and use it to compute the string formation temperature throughout the model parameter space. Requiring both a viable first-order transition and a PTA-compatible gravitational wave signal selects a narrow region in the model parameter space, in the $(\sin^2θ_w,\sqrtβ)$ plane, where $θ_w$ is the dark-sector weak mixing angle and $β\equiv M_Φ^2/M_{Z}^2$ is the squared Higgs-to-$Z$ mass ratio. Thermal effects modify the zero-temperature picture significantly, shifting the PTA-compatible region towards lower values of the dark fine-structure constant $α'$ and larger values of the monopole-to-string-tension ratio $κ$.

As has been shown by multiple authors in recent decades, it is possible to reformulate various portions of the standard model over the ring of complex quaternions. In this paper, we utilize a complex quaternion spin representation of the spacetime algebra to derive the magnetic moments of standard model fermions and the $W^\pm$ boson. The moments calculated are not limited to those with the photon. We account for coupling to the magnetic fields of each standard model gauge boson. We naively assume that fermions coupled to weak isospin have magnetic moments with the charged bosons. Upon assuming these charged moments exist, we realize that they are to be influenced by the neutral, pseudovector-valued magnetic fields that are observed when a charged particle is moving. Visualizing the derived moments of fermions and charged bosons together, we find a possible explanation for the parity asymmetry observed in charged weak interactions.

We propose a photonic scheme for analog quantum simulation of a $U(1)$ Lattice Gauge Theory (LGT) with dynamical matter based on the Jaynes-Cummings-Hubbard (JCH) model. Here, an array of interacting cavities in the strong-coupling regime of cavity Quantum Electrodynamics is mapped onto the alternating matter and gauge-field sites of the spin-1/2 Quantum Link Model. In contrast to other analog LGT quantum simulation methods, our approach implements the desired gauge-invariant dynamics through the hopping of polaritonic excitations among the array sites. The hopping is mapped to the gauge theory via precise tuning of polaritonic resonances in individual cavities. Using exact diagonalization, we show that the real-time evolution of the JCH model accurately replicates that of a Quantum Link Model. Finally, we discuss feasible routes to the beyond-classical simulation capability with scalable implementations in photonic and superconducting systems. This provides a novel route towards understanding the real-time dynamics of lattice gauge theories with matter in higher dimensions.