We perform a comparative Bayesian analysis of fermionic and bosonic dark matter admixed neutron stars (DMANS) by incorporating a comprehensive set of theoretical, experimental, and astrophysical constraints. The hadronic matter equation of state (EoS) is modeled using a relativistic mean-field approach, constrained by chiral effective field theory (χEFT) calculations at low densities, finite nuclei and heavy-ion collision data at intermediate densities, and neutron star (NS) observations at high densities. For the dark sector, we consider fermionic dark matter (FDM) interacting via a dark vector meson, and two bosonic dark matter models (BDM1 and BDM2) characterized by self-interacting scalar fields. Bayesian inference is employed to constrain the model parameters, including the dark matter mass, coupling strength, and dark matter fraction within NSs. Our analysis finds that all models yield consistent nuclear matter parameters, allowing a small dark matter fraction under 10%. The presence of dark matter slightly softens the EoS, leading to a modest reduction in NS mass, radius, and tidal deformability, though all models remain compatible with NICER and GW170817 observations. The log-evidence and likelihood analyses reveal no statistical preference among the FDM and BDM models, indicating that current astrophysical data cannot decisively distinguish between fermionic and bosonic dark matter scenarios. This study provides a unified statistical framework to constrain dark matter properties using NS observables.

Non-perturbative flavor asymmetry in the nucleon and deuteron: The light-front Hamiltonian effective field theory approach

A bstract We forecast the reach of the upcoming Cherenkov Telescope Array Observatory (CTAO) to the full set of real representations within the paradigm of minimal dark matter. We employ effective field theory techniques to compute the annihilation cross section and photon spectrum that results when fermionic dark matter is the neutral component of an arbitrary odd and real representation of SU(2), including the Sommerfeld enhancement, next-to-leading log resummation of the relevant electroweak effects, and the contribution from bound states. We also compute the corresponding signals for scalar dark matter, with the exception of the bound state contribution. Results are presented for all real representations from the ~ 3 TeV triplet (or wino), a 3 of SU(2), to the ~ 300 TeV tredecuplet, a 13 of SU(2) that is at the threshold of the unitarity bound. Using these results, we forecast that with 500 hrs of Galactic Center observations and assuming background systematics are controlled at the level of $$ \mathcal{O}\left(1\%\right) $$ O 1 % , then should no signal emerge, CTAO could exclude all representations up to the 11 of SU(2) in even the most conservative models for the dark-matter density in the inner galaxy, in both the fermionic and scalar dark matter cases. Assuming the default CTAO configuration, the tredecuplet will marginally escape exclusion, although we outline steps that CTAO could take to test even this scenario. In summary, CTAO appears poised to make a definitive statement on whether real WIMPs constitute the dark matter of our universe.

Ringdown analysis of rotating black holes in effective field theory extensions of general relativity

Heavy right-handed neutrinos are highly motivated due to their connection with the origin of neutrino masses via the seesaw mechanism. If the right-handed neutrino Majorana mass is at or below the weak scale, direct experimental discovery of these states is possible in laboratory experiments. However, there is no basis to expect right-handed neutrinos to be so light since the Majorana mass is a technically natural parameter and could comfortably reside at any scale, including at scales far above the weak scale. Here we explore the possibility that the right-handed neutrino Majorana mass originates from electroweak symmetry breaking. Working within an effective theory with two Higgs doublets, a nonzero lepton number is assigned to the bilinear operator built from the two Higgs fields, which is then coupled to the right-handed neutrino mass operator. In tandem with the neutrino Yukawa coupling, following electroweak symmetry breaking a seesaw mechanism operates, generating the light Standard Model neutrino masses along with right-handed neutrinos with masses below the electroweak scale. This scenario leads to novel phenomenology in the Higgs sector, which may be probed at the LHC and at future colliders. There are also interesting prospects for neutrinoless double beta decay and lepton flavor violation. We also explore some theoretical aspects of the scenario, including the technical naturalness of the effective field theory and ultraviolet completions of the right-handed neutrino Majorana mass.

Abstract In this paper, we investigate the quantum gravitational corrections to the thermodynamical quantities of Reissner-Nordström black holes within the framework of effective field theory. The effective action originates from integrating out massless particles, including gravitons, at the one-loop level. We perform a complete thermodynamic analysis for both non-extremal and extremal black holes, and are mainly concerned about the shift in the charge-to-mass ratio $q/M$ that plays an important role in analyzing the weak gravity conjuecture. For non-extremal black holes, we identify a relationship between the shift in the charge-to-mass ratio and the thermodynamic stability of the black holes. For extremal black holes, we show that quantum gravity effects naturally lead to the super-extremality $q/M>1$ of charged black holes.

We investigate the lepton flavor violating (LFV) process e + e − → e + e − e μ ( e = e − , e + , μ = μ − , μ + ) at future circular colliders, probing the effective γ γ e μ interaction through photon fusion. Within an effective field theory framework compatible with theoretical and experimental constraints, we identify regions in the parameter space of the effective couplings where the signal could be observed at the Circular Electron-Positron Collider at s = 240 GeV and the Future Circular Collider (FCC-ee) at s = 240 and 350 GeV. Our analysis leverages distinctive kinematic distributions—particularly the transverse momentum of the scattered electron p T ( e − scattered ) and the central muon p T μ —to achieve efficient signal-background separation. By employing a neural network classifier, we enhance the sensitivity beyond traditional cut-based methods, demonstrating the discovery potential of these facilities for LFV searches in the clean environment of e + e − collisions.

A bstract The description of low-energy (“soft”) gravitons using universal theorems continues to attract attention. In this paper, we consider the emission of two soft gravitons, using a previously developed formalism that describes (next-to) soft graviton emission in terms of generalised Wilson lines (GWLs). Based on Schwinger’s proper time methods, the GWL allows for a systematic accounting of graviton emission from external hard particles in the amplitude, as well as from three-graviton vertices located off the individual worldlines. By combining these effects, previously derived results for the leading double soft graviton theorem are recovered. Still, the formalism allows us to go further in deriving new universal double soft graviton terms at subleading order in the momentum expansion. We further demonstrate how gauge invariance can be utilized to account for double soft graviton emissions within the non-radiative amplitude, including the effects of non-zero initial positions of the hard particles. Our results can be packaged into an exponential dressing operator, and we comment on possible applications to the effective field theory for binary scattering processes.

Nucleon-nucleon scattering up to next-to-leading order in manifestly Lorentz-invariant chiral effective field theory: Low phases and the deuteron

We present the first abinitio lattice calculations of the proton-rich tin isotopes ^{99}Sn to ^{102}Sn using nuclear lattice effective field theory with high-fidelity two- and three-nucleon forces. For a given set of three-nucleon couplings, we reproduce binding energies with ∼1% accuracy for the even-even systems and obtain energy splitting and two-nucleon separation energies in agreement with experiment. Our results confirm the N=50 shell closure and reveal that the binding energy of ^{99}Sn lies below values extrapolated from heavier isotopes.

A bstract We use standard techniques of hydrodynamics to construct a relativistic effective field theory for the low energy dynamics of nearly critical superfluids. In an appropriate non-relativistic limit, our theory predicts an additional coefficient when compared and contrasted to earlier work of Khalatnikov and Lebedev. In addition, we provide an alternative derivation of the same effective theory, using the Keldysh-Schwinger framework for non-equilibrium systems. Finally, we comment on the comparison with the results of an appropriate holographic computation presented in a companion paper. This provides further evidence in support of the theory we propose and confirms the existence of the extra coefficient we identified.

We compute the two-loop effective field theory (EFT) power spectrum of dark matter density fluctuations in Λ CDM using the recently proposed COBRA method (Bakx. et al, 2025). With COBRA, we are able to evaluate the two-loop matter power spectrum in ∼ 1 millisecond at ∼ 0.1 % precision on one CPU for arbitrary redshifts and on scales where perturbation theory applies. As an application, we use the nonlinear matter power spectrum from the Dark Sky simulation to assess the performance of the two-loop EFT power spectrum compared to the one-loop EFT power spectrum at z = 0 . We find that, for volumes typical for Stage IV galaxy surveys, V = 25 ( Gpc / h ) 3 , the two-loop EFT can provide unbiased cosmological constraints on Ω m , H 0 and A s using scales up to k max = 0.26 h / Mpc , thereby outperforming the constraints from the one-loop EFT ( k max = 0.11 h / Mpc ). The Figure of Merit on these three parameters increases by a factor ∼ 2.6 and the one-dimensional marginalized constraints improve by ∼ 35 % for Ω m , ∼ 20 % for H 0 and ∼ 15 % for A s .

A bstract We compute $$ \mathcal{O}\left({\alpha}^2Z\right) $$ O α 2 Z radiative corrections to superallowed β decays with a heavy-particle effective field theory that systematically describes the interactions of low-energy ultrasoft photons with nuclei. We calculate two-loop virtual and one-loop real-virtual amplitudes by reducing the Feynman integrals to a set of master integrals, which we solve analytically using a variety of techniques. These techniques can be applied to other phenomenologically interesting observables. The ultrasoft corrections can then be combined with contributions arising from the exchange of potential photons to obtain the complete $$ \mathcal{O}\left({\alpha}^2Z\right) $$ O α 2 Z correction to the decay rate, with resummation of large logarithms of the electron energy times the nuclear radius. We find that $$ \mathcal{O}\left({\alpha}^2Z\right) $$ O α 2 Z ultrasoft loops induce a relative correction to the decay rate that ranges from 0.7 ∙ 10 − 3 in the decay of 10 C to 3.6 ∙ 10 − 3 in the decay of 54 Co, and will thus impact the extraction of V ud at the permille level. We show that the inclusion of these corrections reduces the residual renormalization scale dependence of the decay rate to a negligible level, making missing ultrasoft perturbative corrections a subdominant source of theoretical uncertainty.

We establish a rigorous correspondence between the Krein space regularization method and the Lagrange multiplier (LM) approach to quantum gravity, extending both to the full Einstein-Hilbert action within the Unified Standard Model with Emergent Gravity-Effective Field Theory (USMEG-EFT) framework. Through explicit calculation of the one-loop effective action using the heat kernel expansion in the LM framework and the modified propagator structure in Krein quantization, we demonstrate that both methods yield identical finite results. The one-loop effective action takes the form [Formula: see text], with coefficients derived from the Seeley-DeWitt heat kernel expansion. The parameter correspondence [Formula: see text] emerges naturally from the regularization structure, with both encoding the finite domain of validity characteristic of an effective field theory. We demonstrate that both methods independently restrict quantum gravitational corrections to one-loop order through structurally isomorphic cancellation mechanisms: opposite-sign propagators in the LM formalism correspond to negative-norm states in Krein space, with higher-loop contributions vanishing identically via binomial summation. We provide detailed analysis of why standard Hilbert space quantization fails due to positive-definiteness constraints, and how the indefinite metric structure of Krein spaces enables systematic divergence cancellation while preserving unitarity in the physical sector. This equivalence provides mutual theoretical support for the USMEG-EFT framework representing the first successful unification of quantum gravity with the Standard Model.

A bstract We study axion-like particles (ALPs) whose dominant interactions are with gluons and third-generation quarks, and whose couplings to light Standard Model (SM) particles arise at one loop. These loop-induced effects lead to ALP decays and production channels that can be probed at the LHC, even when tree-level couplings are absent. Using an effective field theory (EFT) description that includes momentum-dependent corrections from radiative effects, we reinterpret a wide range of LHC measurements via the Contur framework to derive model-independent constraints on the ALP parameter space. We show that LHC data place meaningful bounds in the plane of effective couplings $$ {c}_t^0/{f}_a $$ c t 0 / f a and $$ {c}_{\overset{\sim }{G}}^0/{f}_a $$ c G ~ 0 / f a , and that these limits are sensitive to the UV origin of the ALP-top and ALP-gluon couplings. We discuss representative scenarios where either $$ {c}_t^0 $$ c t 0 or $$ {c}_{\overset{\sim }{G}}^0 $$ c G ~ 0 vanishes at the matching scale, and highlight the role of EFT running and mixing in generating observable signals. We also assess the domain of validity of the EFT approach by comparing the typical momentum transfer $$ \sqrt{\hat{s}} $$ s ̂ in sensitive regions to the underlying scale f a . Our results demonstrate the power of loop-aware EFT reinterpretation of SM measurements in probing otherwise elusive ALP scenarios. The framework presented here can be readily extended to include couplings to other fermions and to accommodate ALP decay or long-lived signatures.

A bstract On-shell amplitudes are invariant under field redefinitions. Nonderivative field redefinitions have a natural interpretation as coordinate transformations on the target manifold. General field redefinitions, which may involve derivatives, can be viewed as coordinate transformations on the field configuration manifold. We present a unified perspective for the geometry of both the target manifold and the field configuration manifold for scalar effective field theories. In both cases, we identify vertices that can be used to build the tree-level amplitudes, with the property that they transform covariantly in the vacuum and on-shell limits. We identify a choice of metric on the field configuration manifold, for which amplitude expressions on the target manifold can be easily reproduced from their counterparts on the field configuration manifold. This clarifies the relation between the well-established framework of field space geometry and recent proposals for functional geometry.

The present study aims to unveil a scenario with a nonminimal secluded dark sector (DS) in an effective field theory (EFT) framework. To explore this, we have examined a suitable extension of the type-X two Higgs doublet model (2HDM) as a potential origin for the secluded DS. The DS comprises a dark matter (DM) candidate and a mediator particle “ a ” and possesses some nonminimal characteristics. It becomes nonthermally populated through diverse dim-6 four-Fermi operators, effectively generated by integrating out the heavier Higgs particles. The analysis further focuses on the consequences of the collision processes DM + a ↔ a + a and DM + DM ↔ a + a occurring within the DS. We have investigated the significance of employing an EFT approach in tracking the temperature evolution of the DS. Within the present framework, the observed relic abundance of the DM can be realized through both dark freeze-out and freeze-in mechanisms. Further, we have delineated the permissible ranges of the relevant parameters, viz., the DM mass ( m χ ≳ 20 GeV ), the portal coupling ( C τ ≲ 10 − 14 GeV − 2 ), and the DS coupling ( λ ≲ 10 − 6 GeV − 2 ), by taking into account the perturbativity of the involved couplings while reproducing the observed DM relic and complying with the bounds from successful big bang nucleosynthesis (BBN) and γ -ray searches.

Positively identifying Higgs effective field theory or standard model effective field theory

A comprehensive assessment of theoretical uncertainties defines an important frontier in nuclear structure research. Ideally, theory predictions include uncertainty estimates that take into account truncation effects from both the interactions and the many-body expansion. While the uncertainties from the expansion of the interactions within effective field theories have been studied systematically using Bayesian methods, many-body truncations are usually addressed by expert assessment. In this work we use a Bayesian framework to study many-body uncertainties within many-body perturbation theory applied to finite nuclei. Our framework is applied to a broad range of nuclei across the nuclear chart calculated from two- and three-nucleon interactions based on chiral effective field theory. These developments represent a step towards a more complete and systematic quantification of uncertainties in calculations of nuclei.

Study of electron-positron annihilation into four pions within chiral effective field theory in the low energy region