We construct exotic compact objects composed entirely of self-interacting asymmetric fermionic dark matter governed by a repulsive Yukawa potential with massive dark interaction boson. By considering the structural, tidal, and rotational properties of solar mass self-gravitating dark-matter systems, and contrasting them against purely baryonic neutron stars, described by the well understood SLy4 equation of state, we hope to shed some light on the place of dark compact systems in the context of gravitational wave astronomy, specifically due to the difficulty parsing mass and radius data from events with no electromagnetic counterpart. Here we consider systems composed of 1 GeV and 10 GeV dark matter. Relevant compact objects are then analyzed and simulated as both static bodies, and rotating systems governed by the Hartle-Thorne formalism to second order. Here within we highlight the differences in key tidal and rotational properties encoded in gravitational wave signals, and analyze how dark objects may mimic or distinguish themselves to current and future gravitational wave observatories.

In this paper, we will demonstrate that a dense quark-matter system in the dual chiral density wave (DCDW) phase behaves as a ferromagnet in the sense that its magnetic-field dependent magnetization remains different from zero even at $B\to 0$. The corresponding permanent magnetization is a function of the baryonic chemical potential $\mu$, decreasing up to zero as $\mu$ increases in the range of intermediate densities ($312\mathrm{MeV}⩽\mu ⩽342\mathrm{MeV}$) and then increasing from zero in the higher density interval $490\mathrm{MeV}⩽\mu ⩽550\mathrm{MeV}$. We will show that this system’s ability to generate permanent magnetization, together with the existence of the axial anomaly, open up the possibility of spontaneously generating a magnetic field coupled to a collinear electric field. The generated magnetic field can reach values up to ${10}^{16}\mathrm{G}$, depending on $\mu$, and the electric field will be 3 orders smaller. The fact that the DCDW phase is able to induce a magnetic field can be seen as its spontaneous tendency to remove the so called Landau-Peierls instability that is present in this single-modulated phase in the absence of a magnetic field. The spontaneous induction of a strong magnetic field at intermediate to high densities can be of interest for the astrophysics of compact stellar objects exhibiting strong magnetic fields as magnetars.

We study the Sudakov form factor on the Coulomb branch of $\mathcal{N}=4$ sYM which endows only external states with masses, and implies that the former is off-shell in the traditional sense. Our consideration is performed at three-loop order in the near mass-shell limit. We use a combination of tools to perform required calculations centered around the method of regions as the main go-to formalism for the asymptotic expansion of emerging parametric Feynman integrals. Explicit separation of quantum loops in terms of hard, collinear, and ultrasoft modes allows us to explore the factorization properties of this infrared-sensitive quantity. While the hard region is cleanly separated from the rest, the ultrasoft-collinear modes remain intertwined. We exhibit effects of factorization violation explicitly in the momentum space making use of the infrared power counting.

We derive relativistic resistive magnetohydrodynamics for a two-component ultrarelativistic plasma directly from kinetic theory. Starting with the Boltzmann-Vlasov equation and using the 14-moment approximation in the Landau frame, we obtain coupled evolution equations for the charge diffusion four-current and the shear-stress tensor. Benchmarking against the usual Israel-Stewart type relaxation form shows that this simplified description is accurate for small viscosity to entropy ($\eta /s$) ratio, vanishing magnetic field, and not so strong electric field. Outside this regime the dynamics depart in a controlled way, i.e., strong electric fields introduce nonlinear backreaction that delays and reduces current peaks, and a sizable shear stress is produced even without a flow profile.

We have performed a theoretical study of the correlation functions of $K^{-}d$ and $K^{+}d$ pairs and compared them with those provided by the ALICE Collaboration from Pb-Pb collisions and also from high-multiplicity p-p collisions in the case of $K^{+}d$. In addition to implementing the effect of the Coulomb force, the $K^{-}d$ and $K^{+}d$ wave functions are derived from the corresponding strong scattering amplitudes that are built employing a unitarized chiral model for the elementary $K^{-}N$ and $K^{+}N$ interactions. We present results for the impulse approximation, which accounts for single-scattering processes of the kaon with the nucleons of the deuteron, as well as for the solution of the Faddeev equations in the so-called fixed center approximation, which includes multiple rescattering effects. The $K^{-}d$ correlation function is shown to be very sensitive to both the size of the source and the relative momentum of the interacting pair, with large deviations from the Coulomb baseline and sizable multistep scattering contributions, effects that are tied to a $\overline{K}N$ strong interaction that is dominated by the influence of the subthreshold resonance $\mathrm{\Lambda }(1405)$. In contrast, the $K^{+}d$ correlation function only differs appreciably from the Coulomb one for relatively small sources, reflecting the mildly repulsive and elastic behavior of the $KN$ strong force. The calculated correlation functions are found to nicely reproduce the experimental data of the ALICE Collaboration. Our study serves to reinforce the validity of the theoretical models employed and demonstrates the value of femtoscopy as a powerful tool for probing hadronic interactions involving strangeness.

We investigate the potential of single-spin components of the spin-density matrix in the $e^{+}{e}^{-}\to t\overline{t}$ process at a future FCC-ee for probing heavy new physics parametrized using the Standard Model effective field theory (SMEFT) framework. We consider the full spectrum of spin observables and the complete angular decomposition of the $t\overline{t}$ production process in our study. We find that single-spin measurements generically provide stronger probes of SMEFT Wilson coefficients than measurements where the $t\overline{t}$ spins are correlated, and that single-spin observables are important for resolving flat directions that can appear in the Wilson-coefficient parameter space.

The next generation of high-luminosity electron-positron colliders, such as the electron-positron Future Circular Collider and the Circular Electron-Positron Collider operating at the $Z$ pole (TeraZ), is expected to deliver unprecedented precision in electroweak measurements. These precision observables are typically interpreted within the Standard Model effective field theory (SMEFT), offering a powerful tool to constrain new physics. However, the large number of independent SMEFT operators allows for the possibility of blind directions, parameter combinations to which electroweak precision data are largely insensitive. In this work, we demonstrate that such blind directions are not merely an artifact of agnostic effective field theory scans, but arise generically in realistic ultraviolet completions involving multiple heavy fields. We identify several concrete multifield extensions of the Standard Model whose low-energy SMEFT projections align with known blind subspaces, and show that these persist even after accounting for renormalization group evolution and finite one-loop matching effects. Our analysis shows that TeraZ will set a new benchmark in precision for indirect searches, but fully probing the space of possible ultraviolet physics requires going beyond this stage. Later electron-positron Future Circular Collider runs at higher center-of-mass energies, together with the hadron-hadron Future Circular Collider, will provide the necessary complementary probes, enabling a far more complete exploration of the SMEFT parameter space.

The discovery of the lepton number violation would be a smoking gun signal for physics beyond the Standard Model, and its most sensitive probe is the search for neutrinoless double beta decay ($0\nu \beta \beta$). Working in the framework of the Standard Model effective field theory (SMEFT), we show that one-loop effects can remarkably improve the tree-level bounds on the new physics scales for several dimension-7 operators. Using ultraviolet model examples, we then showcase the competition among $0\nu \beta \beta$ contributions induced by dimension-7 and loop-level dimension-5 SMEFT operators.

Current dark matter direct detection experiments have low sensitivity to sub-GeV dark matter. In this work, we demonstrate that rare $B$ and $K$ meson decays with missing energy in the final state can serve as efficient probes in this mass range. We analyze a generic $Z^{\prime }$ portal dark matter model and derive upper limits on its parameters from experimental bounds on the rare $B$ and $K$ meson decays. Our results show that such meson decay processes provide complementary constraints to current direct detection experiments for sub-GeV dark matter, particularly for interaction forms mediated by dark matter momentum-dependent operators.

We investigate $CP$-violating effects in electroweak interactions at future high-energy muon colliders within the Standard Model effective field theory framework. Focusing on four dimension-six $CP$-odd operators—${\mathcal{O}}_{\tilde{W}},{\mathcal{O}}_{H\tilde{W}},{\mathcal{O}}_{H\tilde{W}B},{\mathcal{O}}_{H\tilde{B}}$—we analyze vector boson fusion production of $W$ and Higgs bosons using $CP$-odd observables and their asymmetries. With detailed simulations including parton showering, hadronization, and detector effects, we derive exclusion sensitivities through a binned likelihood analysis. For example, at $\sqrt{s}=3\mathrm{TeV}$ with $2{\mathrm{ab}}^{-1}$, the coefficient $C_{\tilde{W}}$ can be constrained at the $\mathcal{O}(0.02)$ level, improving to $\mathcal{O}(0.008)$ at 10 TeV with $2{\mathrm{ab}}^{-1}$, and $\mathcal{O}(0.003)$ with $10{\mathrm{ab}}^{-1}$. These results significantly surpass current LHC and projected International linear collider sensitivities, demonstrating the unique potential of high-energy muon colliders to provide direct and model-independent probes of $CP$ violation in the electroweak sector.

The quest for a common origin of neutrino mass and baryogenesis is one of the long-standing goals in particle physics. A minimal gauge extension of the Standard Model by $U(1{)}_{\mathrm{B}-\mathrm{L}}$ symmetry provides a unique scenario to explain the tiny mass of neutrinos as well as the observed baryon asymmetry, both by virtue of three right-handed neutrinos (RHNs). Additionally, the $U(1{)}_{\mathrm{B}-\mathrm{L}}$ breaking scalar that generates mass of the RHNs can produce a stochastic gravitational wave background (SGWB) via cosmological first-order phase transition. In this work, we systematically investigate TeV-scale leptogenesis considering flavor effects that are crucial in the low-temperature regime. We also explore all possible RHN production channels, which can have significant impact on the abundance of RHNs, depending on the value of the $U(1{)}_{\mathrm{B}-\mathrm{L}}$ gauge coupling. We demonstrate that the strong dependence of the $U(1{)}_{\mathrm{B}-\mathrm{L}}$ gauge sector on the baryon asymmetry as well as SGWB production can be utilized to probe a region of the model parameter space. In particular, we find that a $U(1{)}_{\mathrm{B}-\mathrm{L}}$ gauge boson with mass $\sim 10\mathrm{TeV}$ and gauge coupling $\sim 0.1$ can explain the observed baryon asymmetry and produces a detectable SGWB in future detectors as well. Importantly, this region falls beyond the reach of the current collider sensitivity.

We consider 4D $SU(N)$ gauge theories coupled to gravity in the causal dynamical triangulation (CDT) approach, focusing on the topological classification of the gauge path integral over fixed triangulations. We discretize the topological charge and, after checking the emergence of topology and the continuum scaling on flat triangulations, we show that topology emerges on thermalized triangulations only in the so-called de Sitter phase of CDT, thus enforcing the link between such phase and semiclassical spacetime. We also provide a tool to visualize the topological structures.

A recent work considered quantum simulation of Quantum Electrodynamics on a lattice in the Coulomb gauge with gauge degrees of freedom represented in the occupation basis in momentum space. Here we consider the more efficient representation of the gauge degrees of freedom in field basis in position space and develop a quantum algorithm for real-time simulation. We show that the continuum Coulomb gauge Hamiltonian is equivalent to the temporal gauge Hamiltonian when acting on physical states consisting of fermion and transverse gauge fields. The Coulomb gauge Hamiltonian is discretized by using the Green’s function of the discrete Laplacian operator under the Dirichlet boundary conditions. Both the continuum Coulomb gauge Hamiltonian and the discretized one proposed here guarantee that the unphysical longitudinal gauge fields are decoupled and commute with the corresponding Hamiltonian. Thus there is no need to impose any constraint. The local gauge field basis and the canonically conjugate variable basis are swapped efficiently using the quantum Fourier transform. We prove that the qubit cost to represent physical states and the gate count for real-time simulation scale polynomially with the lattice size, energy, time, accuracy, and Hamiltonian parameters in lattice units. The gate cost here for implementing the time evolution of the gauge field is reduced at least by a factor on the order of ${10}^8$ for modest lattice size and accuracy level compared with the previous work.

We develop a strategy for computing the $B\to K{\ell }^{+}{\ell }^{-}$ and ${\overline{B}}_s\to \gamma {\ell }^{+}{\ell }^{-}$ decay amplitudes using lattice QCD (where ${\ell }^{\pm }$ are charged leptons). We focus on those terms which contain complex contributions to the amplitude, due to on-shell intermediate states propagating between the weak operator and electromagnetic current(s). Such terms, which are generally estimated using model calculations and represent significant uncertainties in the phenomenological predictions for these decays, cannot be computed using standard lattice QCD techniques. It has recently been shown that such contributions can be computed using spectral density methods and our proposed strategy, which we discuss in detail, is built on this approach. The complex contributions include the “charming penguins” [matrix elements of the current-current operators $O_1^{(c)}$ and $O_2^{(c)}$ defined in Eq. (6) below], in which the charm-quark loop can propagate long distances, particularly close to the region of charmonium resonances. They also include the contributions from the chromomagnetic operator [$O_8$ in standard notation, defined in Eq. (8) below]. We discuss the renormalization of the ultraviolet divergences, and in particular those which arise due to “contact” terms, and explain how those which appear as inverse powers of the lattice spacing can be subtracted nonperturbatively. We apply the spectral density methods in an instructive exploratory computation of the charming penguin diagram in $B\to K{\ell }^{+}{\ell }^{-}$ decays in which the virtual photon is emitted from the charm-quark loop [the diagram in Fig. 1(a) below] and discuss the prospects and strategies for the reliable determination of the amplitudes in future dedicated computations; computations which are, however, beyond the scope of the present paper.

We investigate the quantum properties of the truly gauge-invariant and conserved charges of two-dimensional Yang-Mills theories, focusing on lattice QCD in the strong coupling regime. The construction of those charges uses the integral version of the ($1+1$)-dimensional Yang-Mills equations, and they correspond to the eigenvalues of a charge operator. The gauge invariance of the charges suggests that they are not confined, hence hadronic states may carry them. Using the path integral formalism with imaginary time (Euclidean), we evaluate the correlation functions of those charges on baryon and meson states through functional integrals over the gauge group $SU(N)$ ($N=2$, 3) and Grassmannian variables—the fermionic fields. Our results show that the expectation values of the lowest nontrivial charges are nonzero for baryon and meson states but vanish for non-gauge-invariant states, supporting the interpretation that hadrons indeed carry these charges. While renormalization effects and higher-order contributions remain to be analyzed, these findings point toward a potential link between gauge-invariant charges and confinement.

Inspired by the observation of the doubly charmed tetraquark state $T_{cc}$ at $pp$ collisions in the inclusive processes, we systematically investigate the production of doubly charmed tetraquark states in exclusive $B_c$ decays. In this work, we assume the $T_{cc}$ as a $D{D}^{*}$ bound state, and then predict the masses of its heavy quark spin symmetry partner $D^{*}{D}^{*}$ (denoted by $T_{cc}^{*}$) as well as their SU(3)-flavor symmetry partners, i.e., $D_s{D}^{*}/D_s^{*}D$ (denoted by $T_{ccs}^{+}$ and $T_{ccs}^{++}$) and $D^{*}{D}_s^{*}$ (denoted by $T_{ccs}^{*+}$ and $T_{ccs}^{*++}$), using the contact range effective field theory. Within the molecular picture, we compute their partial decay widths and production rates in $B_c$ meson decays. We identify the decays $B_c\to D^0{D}^0{\pi }^{+}{\overline{D}}^0$ and $B_c\to D_s^{+}{D}^0{\pi }^{+}{D}^{-}$ as promising channels to observe the tetraquark states $T_{cc}^{(*)}$ and $T_{ccs}^{(*)++}$, respectively. Finally, by combining these results with $B_c$ production cross sections, we estimate the expected event yields for these states in the upcoming LHC Runs 3 and 4. Our results indicate that the $T_{ccs}^{+}$ and $T_{ccs}^{*++}$ states are likely to be observed in $B_c$ decays, while it is quite difficult for the $T_{cc}$ and $T_{cc}^{*}$ states.

We investigate the partonic origin of the proton longitudinal spin using spin-dependent energy correlators measured in lepton-hadron collisions with longitudinally polarized proton beams. These observables encode angular correlations in energy flow and are sensitive to the spin-momentum structure of confined partons. Using soft-collinear effective theory, we analyze the correlation patterns in both nearly back-to-back and forward limits, which establishes a direct correspondence with longitudinally polarized transverse momentum-dependent distributions (TMDs) and nucleon energy correlators (NECs). The TMDs and NECs allow consistent matching onto hard radiation regions and provide a comprehensive description of the transition from perturbative parton branching to nonperturbative confinement. Using renormalization group evolution, we obtain joint next-to-next-to-next-to-leading and next-to-next-to-leading logarithmic quantitative predictions for spin-dependent energy correlation patterns in the current and target fragmentation regions. The framework provides new theoretical insight into how the internal motion and spin of partons contribute to the formation of the proton longitudinal spin and offers an experimental paradigm for probing the interplay between color confinement and spin dynamics at the forthcoming Electron-Ion Collider.

We perform a Lorentz gauge evaluation of the single soft-photon bremsstrahlung radiative corrections to the unpolarized elastic lepton-proton scattering cross section at low energies, using the framework of heavy baryon chiral perturbation theory ($\mathrm{HB}\chi \mathrm{PT}$). We systematically incorporate all next-to-leading-order [i.e., $\mathcal{O}({\alpha }^3/M)$] contributions to the cross section arising from radiative and proton’s low-energy recoil effects. An important component of the soft-photon bremsstrahlung corrections arises from the interference between lepton and proton bremsstrahlung processes, which are characterized as charge-odd. We identify a class of Feynman diagrams involving the final-state radiating proton that induces a chiral enhancement, thereby modifying the naive amplitude hierarchy based on the standard chiral power-counting scheme. The recently derived $\mathrm{HB}\chi \mathrm{PT}$ result for the analytically computed exact two-photon exchange counterpart at next-to-leading order is combined with our charge-odd soft-photon bremsstrahlung contribution to yield the complete charge-odd radiative correction. By incorporating the leading hadronic correction to the one-photon exchange process within the charge-even radiative correction, we obtain a prediction for the charge asymmetry observable, which can be compared with forthcoming MUon Scattering Experiment data on elastic lepton-antilepton scattering off the proton. In all our calculations, we use finite lepton masses.

The Heavy Photon Search experiment (HPS) is a fixed-target, electron beam experiment designed to search for $e^{+}{e}^{-}$ mass resonances and displaced decays using a forward acceptance spectrometer. This paper details the search for naturally long-lived “dark” vector mesons ($V_D$) arising from a dark sector of beyond-Standard-Model strongly interacting massive particles, characterized by a QCD-like $SU(3{)}_D$ symmetry and coupled to the Standard Model photon via a new $U(1{)}_D$ gauge interaction mediated by the “heavy photon,” or $A^{\prime }$. The results are based on an integrated luminosity of $10608{\mathrm{nb}}^{-1}$ collected during the 2016 HPS engineering run. The displaced vertex search for $V_D\to e^{+}{e}^{-}$ in the $e^{+}{e}^{-}$ invariant mass range 39–179 MeV showed no statistically significant evidence for signal above the QED background.

The upcoming Electron-Ion Collider (EIC) will address several outstanding puzzles in modern nuclear physics. Key questions—such as the partonic structure of nucleons and nuclei and the origin of their mass and spin—can be explored through high-energy electron-proton and electron-nucleus collisions. To maximize its scientific reach, the EIC community has advocated for the addition of a second interaction region equipped with a detector complementary to the EIC general purpose collider detector, ePIC. The preconceptual design of this interaction region aims to provide a different configuration from the first interaction region, which enhances forward acceptance at very small scattering angles ($\theta \sim 0\mathrm{mrad}$). This machine configuration would significantly benefit exclusive, tagging, and diffractive physics programs, complementing those of the ePIC experiment. In particular, accessing coherent diffractive processes on light nuclei by tagging of the full, intact nucleus is essential for mapping their spatial parton distributions. In this work, we present an exploratory study of the detection capabilities for light nuclei at a second EIC interaction region, with a detailed discussion of the accessible kinematic phase space and its implications for imaging.