We study rotating compact stars that are mixtures of the ordinary nuclear matter in a neutron star and fermionic dark matter. After deriving equations describing a slowly rotating system made up of an arbitrary number of perfect fluids, we specialize to the two-fluid case, where the first fluid describes ordinary matter and the second fluid describes dark matter. Electromagnetic observations of the moment of inertia and angular momentum directly probe ordinary matter and not dark matter. Upon taking this into account, we show that the $I$-Love-$Q$ relations for dark matter admixed neutrons stars can deviate significantly from the standard single-fluid relationships.

The inclusive probability to record an electron in elastic electromagnetic scattering of an electron by a spin one-half hadron is obtained, the initial quantum states of the electron and the hadron being described by the density matrices of a general form. Contrary to the Rosenbluth formula for the differential cross section for this process, the first nontrivial contribution to the inclusive probability turns out to be of order $\alpha$ and not ${\alpha }^2$. This contribution describes the interference between the trivial contribution to the $S$-matrix and the leading contribution to its connected part. The explicit expression for this interference terms is derived. For example, for Gaussian wave packets the interference contribution to the inclusive probability is of relative order $2\times {10}^{-2}$ in comparison with the contribution of the free passed particle for the nonrelativistic proton and the 10 MeV electron with the normal deviation of momenta in the electron and hadron wave packets of order 10 keV. It is shown that the same interference term arises when the electron is scattered by the classical electromagnetic field produced by the hadron electromagnetic current averaged with respect to the free evolving density matrix of the hadron, even in the case of a single hadron. The interference term describes coherent scattering of the electron by the hadron wave packet and is immune to the quantum recoil experienced by a hadron due to scattering. The effective electron mass operator is found on the mass shell.

We obtain stability criteria for diffusive inviscid multicomponent Israel-Stewart hydrodynamics with and without background or dynamic electromagnetic fields. Our analysis is grounded on the maximum entropy principle, and it provides stability conditions that are valid around all thermodynamic equilibria, including rotating equilibria, charged equilibria, and equilibria in a background gravitational field. We prove that the electromagnetic part of the information current is stable and causal by construction, and, therefore, the stability criteria found for Israel-Stewart theories of hydrodynamics automatically extend to similar formulations of magnetohydrodynamics.

The precise determination of the leptonic $CP$-phase is one of the major goals for future generation long baseline experiments. On the other hand, if new physics beyond the Standard Model exists, a robust determination of such a $CP$-phase may be a challenge. Moreover, it has been pointed out that, in this scenario, an apparent discrepancy in the $CP$-phase measurement at different experiments may arise. In this work, we investigate the determination of the Dirac $CP$-phase and the atmospheric mixing angle ${\theta }_{23}$ at several long-baseline configurations: ESSnuSB, T2HKK, and a DUNE-like experiment. We use the nonstandard neutrino interactions (NSI) formalism as a framework. We found that complementary between ESSnuSB and a DUNE-like experiment will be favorable to obtain a reliable value of the $CP$-phase, within the aforementioned scenario. Moreover, the T2HKK proposal can help to constrain the matter NSI parameters.

We use parity ($P$) to set ${\theta }_{\mathrm{QCD}}$ to zero in the minimal left-right symmetric model with a bidoublet Higgs, add a heavy vectorlike quark family, and obtain in a novel manner the Nelson-Barr (NB) form associated so far only with spontaneous $CP$ solution to the strong $CP$ puzzle. Our solution does not have the “coincidence of scales problem”, that typically plagues NB models. $P$ protects $\overline{\theta }$, if it breaks at a scale $v_R$ below the mass $M$ of the heavy quarks, and $\overline{\theta }\sim {10}^{-9}(v_R/M{)}^2$ is radiatively generated, which can be acceptably small. On the other hand, if $M<v_R$, the $\overline{\theta }\sim {10}^{-9}$ generated by the NB mechanism is too large, but if ${\delta }_{\mathrm{CKM}}$ is obtained without the NB form, surprisingly a lower irreducible $\overline{\theta }\sim ({10}^{-13}\text{to}{10}^{-10})\ln (v_R/M)$, testable by neutron electric dipole moment experiments is generated. No leptonic $CP$ violation is generated (Dirac phase ${\delta }_{CP}=0or\pi$ in Pontecorvo-Maki-Nakagawa-Sakata matrix) which makes the minimal model testable by neutrino experiments. We also discuss some challenges in a nonminimal model that generates leptonic $CP$ violation. Lastly but importantly, we find with doublet rather than bidoublet Higgses, that there is an automatic NB solution on imposing $CP$ [the NB form is accidental due to $SU(2{)}_R$], which does not require generalized parity and needs just one mirror generation.

We consider a gauge symmetry extension of the standard model given by $SU(3{)}_C\otimes SU(2{)}_L\otimes U(1{)}_X\otimes U(1{)}_N\otimes {\mathbb{Z}}_2$ with minimal particle content, where $X$ and $N$ are family dependent but determining the hypercharge as $Y=X+N$, while ${\mathbb{Z}}_2$ is an exact discrete symmetry. In our scenario, $X$ (while $N$ is followed by $X-Y$) and ${\mathbb{Z}}_2$ charge assignments are inspired by the number of fermion families and the stability of dark matter, as observed, respectively. We examine the mass spectra of fermions, scalars, and gauge bosons, as well as their interactions, in the presence of a kinetic mixing term between $U(1{)}_{X,N}$ gauge fields. We discuss in detail the phenomenology of the new gauge boson and the right-handed neutrino dark matter stabilized by ${\mathbb{Z}}_2$ conservation. We obtain parameter spaces simultaneously satisfying the recent CDF $W$-boson mass, electroweak precision measurements, particle colliders, as well as dark matter observables, if the kinetic mixing parameter is not necessarily small.

We investigate the potential of the warped extradimension framework as an explanation for the recently observed stochastic gravitational background at nHz frequencies in pulsar timing arrays (PTA). Our analysis reveals that the PTA data can be effectively accommodated by a first-order phase transition triggered by a radion at the MeV-GeV scale feebly coupled to the Standard Model. Remarkably, this outcome remains robust irrespective of the specific details of the warped extradimension embedding, providing a foundation for future investigations aiming to develop concrete extradimension descriptions of Nature. We also demonstrate that many existing embeddings are not viable, as their radion and graviton phenomenology clash with a MeV–GeV scale radion. As a possible way out, we sketch a promising solution involving multiple branes, wherein the light radion, graviton, and ensuing light resonances remain consistent with collider bounds and gravity tests.

We find a simple spin Hamiltonian to describe physical states of ($2+1$)-dimensional SU(2) lattice gauge theory on a honeycomb lattice with a truncation of the electric field representation at $j_{\max }=\frac{1}{2}$. The simple spin Hamiltonian contains only local products of Pauli matrices, even though Gauss’s law has been completely integrated out.

The path optimization method, which is proposed to control the sign problem in quantum field theories with continuous degrees of freedom by machine learning, is applied to a spin model with discrete degrees of freedom. The path optimization method is applied by replacing the spins with dynamical variables, via the Hubbard-Stratonovich transformation, and the sum with the integral. The one-dimensional (Lenz-)Ising model with a complex coupling constant is used as a laboratory for the sign problem in the spin model. The average phase factor is enhanced by the path optimization method, indicating that the method can weaken the sign problem. Our result reproduces the analytic values with controlled statistical errors.

We study the nature of the chiral symmetry restoration within the Yukawa model with spontaneous symmetry breaking. We work with scalar and fermion fields which are subject to the effects of a rotating system. In this work, we show the derivation of the scalar field propagator in a rotating medium using the Fock-Schwinger proper-time method. We compute analytically the effective potential in the high-temperature approximations, including the contribution of the ring diagrams to account for the plasma screening properties. We study the chiral transition as we vary the angular velocity $\mathrm{\Omega }$, the boson self-coupling $\lambda$ and the fermion-boson coupling $g$. We show that the critical temperature for the restoration of chiral symmetry always starts with decreasing behavior, until it reaches a minimum and from there when increasing $\mathrm{\Omega }$, we observe $T_c$ increases monotonically. In all the phase transition lines in the $T-\mathrm{\Omega }$ plane reported, we obtain that the rotating effects are able to change the order of the phase transition.

We study the fully strange tetraquark states with the exotic quantum numbers $J^{PC}=0^{+-}$ and $2^{+-}$. We construct their corresponding diquark-antidiquark interpolating currents and apply the QCD sum rule method to calculate both their diagonal and off-diagonal correlation functions. The obtained results are used to construct some mixing currents that are nearly noncorrelated, from which we extract the masses of the lowest-lying states to be $M_{0^{+-}}=2.47_{-0.44}^{+0.33}$ and $M_{2^{+-}}=3.07_{-0.33}^{+0.25}\mathrm{GeV}$. We apply the Fierz rearrangement to transform the diquark-antidiquark currents to be the combinations of meson-meson currents, and the obtained Fierz identities indicate that these two states may be searched for in the $P$-wave $\varphi (1020)f_0(1710)/\varphi (1020)f_2^{\prime }(1525)(\to \varphi K\overline{K}/\varphi \pi \pi )$ channels.

We investigate the mechanics of the proton by examining the flavor-decomposed proton cosmological constants and generalized vector form factors. The interplay of up, down, and strange quarks within the proton is explored, shedding light on its internal structure. The contributions of strange quarks play a crucial role in the $D$-term and cosmological constants. We find that the flavor blindness of the isovector $D$-term form factor is only valid in flavor SU(3) symmetry.

Heavy vector mesons provide important information about the quark gluon plasma (QGP) formed in heavy ion collisions. This happens because the fraction of quarkonium states that are produced depends on the properties of the medium. The intensity of the dissociation process in a plasma is affected by the temperature, the chemical potential and the presence of magnetic fields. These effects have been studied by many authors in the recent years. Another important factor that can affect the dissociation of heavy mesons, and still lacks of a better understanding, is the rotation of the plasma. Noncentral collisions form a plasma with angular momentum. Here we use a holographic model to investigate the thermal spectrum of bottomonium quasistates in a rotating medium in order to describe how a nonvanishing angular velocity affects the dissociation process.

We determine masses of light quarks ($m_u,m_d,m_s$) using Borel-Laplace sum rules and renormalization group summed perturbation theory (RGSPT) from the divergence of the axial vector current. The RGSPT significantly reduces the scale dependence of the finite-order perturbative series for the renormalization group invariant quantities such as spectral function, the second derivative of the polarization function of the pseudoscalar current correlator, and its Borel transformation. In addition, the convergence of the spectral function is significantly improved by summing all running logarithms and kinematical ${\pi }^2$-terms. Using RGSPT, we find $m_s(2\mathrm{GeV})=104.34_{-4.21}^{+4.32}\mathrm{MeV}$ and $m_d(2\mathrm{GeV})=4.21_{-0.45}^{+0.48}\mathrm{MeV}$ leading to $m_u(2\mathrm{GeV})=2.00_{-0.38}^{+0.33}\mathrm{MeV}$.

Proper interpretation of past, current, and future data on lepton-nucleus reactions requires a clear separation between quantum electrodynamics and strong interaction effects inside the nucleus. First studies of QED in-medium lepton dynamics have set a theoretical framework to derive electron-nucleus and (anti)neutrino-nucleus cross section corrections. We employ this approach to quantitatively compute the effects of Glauber photon-mediated multiple rescattering within the nuclear medium. We find that the relativistic charged lepton acquires momentum of order 10 MeV transverse to its direction of propagation inside the nucleus. This broadening sizably deflects expected electron tracks and suppresses scattering cross sections. Precise extraction of the nucleon and nuclear structure by electron and muon probes should, thus, take the QED nuclear medium angular redistribution of particles into account. Our results further show that the associated effects in (anti)neutrino-nucleus scattering with fixed final-lepton energy are significant only at the kinematical end points.

Dark matter is undoubtedly one of the fundamental, albeit unknown, components of the standard cosmological model. The failure to detect weakly interacting massive particles, the most promising candidate particle for cold dark matter, actually opens the way for the exploration of viable alternatives of which ultralight bosonic particles with masses $\sim {10}^{-21}\mathrm{eV}$ represent one of the most encouraging. Numerical simulations have shown that such particles form solitonic cores in the innermost parts of virialized galactic halos that are supported by internal quantum pressure on characteristic $\sim \mathrm{kpc}$ de Broglie scales. In the Galaxy, this halo region can be probed by means of S-stars orbiting the supermassive black hole Sagittarius ${\mathrm{A}}^{*}$ to unveil the presence of such a solitonic core and, ultimately, to bound the boson mass $m_{\psi }$. Employing a Monte Carlo Markov Chain algorithm, we compare the predicted orbital motion of S2 with publicly available data and set an upper bound $m_{\psi }\lesssim 3.2\times {10}^{-19}\mathrm{eV}$ on the boson mass, at 95% confidence level. When combined with other galactic and cosmological probes, our constraints help to reduce the allowed range of the bosonic mass to $(2.0\lesssim m_{\psi }\lesssim 32.2)\times {10}^{-20}\mathrm{eV}$, at the 95% confidence level, which opens the way to precision measurements of the mass of the ultralight-bosonic dark matter.

We propose a novel framework where baryon asymmetry of the Universe can arise due to forbidden decay of dark matter (DM) enabled by finite-temperature effects in the vicinity of a first-order phase transition (FOPT). In order to implement this novel cogenesis mechanism, we consider the extension of the standard model by one scalar doublet $\eta$, three right-handed neutrinos (RHNs), all odd under an unbroken $Z_2$ symmetry, popularly referred to as the scotogenic model of radiative neutrino mass. While the lightest RHN $N_1$ is the DM candidate and stable at zero temperature, there arises a temperature window prior to the nucleation temperature of the FOPT assisted by $\eta$, where $N_1$ can decay into $\eta$ and leptons, generating a nonzero lepton asymmetry which gets converted into baryon asymmetry subsequently by sphalerons. The requirement of successful cogenesis together with a first-order electroweak phase transition not only keeps the mass spectrum of new particles in the sub-TeV ballpark within reach of collider experiments, but also leads to observable stochastic gravitational wave spectrum which can be discovered in planned experiments like the Laser Interferometer Space Antenna.

Using quantum simulations on classical hardware, we study the phase diagram of the massive Schwinger model with a $\theta$ term at finite chemical potential $\mu$. We find that the quantum critical point in the phase diagram of the model can be detected through the entanglement entropy and entanglement spectrum. As a first step, we chart the phase diagram using conventional methods by computing the dependence of the charge and chiral condensates on the fermion mass $m$, coupling constant $g$, and the chemical potential $\mu$. At zero density, the Schwinger model possesses a quantum critical point at $\theta =\pi$ and $m/g\simeq 0.33$. We find that the position of this quantum critical point depends on the chemical potential. Near this quantum critical point, we observe a sharp maximum in the entanglement entropy. Moreover, we find that the quantum critical point can be located from the entanglement spectrum by detecting the position of the gap closing point.

General teleparallel theories assume that curvature is vanishing in which case gravity can be solely represented by torsion and/or nonmetricity. Using differential form language, we express the Riemannian Gauss-Bonnet invariant concisely in terms of two general teleparallel Gauss-Bonnet invariants, a bulk and a boundary one. Both terms are boundary terms in four dimensions. We also find that the split is not unique and present two possible alternatives. In the absence of nonmetricity our expressions coincide with the well-known metric teleparallel Gauss-Bonnet invariants for one of the splits. Next, we focus on the description where only nonmetricity is present and show some examples in different spacetimes. We finish our discussion by formulating novel modified symmetric teleparallel theories constructed with our new scalars.

The eccentricity of binary black-hole mergers is predicted to be an indicator of the history of their formation. In particular, eccentricity is a strong signature of dynamical formation rather than formation by stellar evolution in isolated stellar systems. We investigate the efficacy of the existing quasicircular parameter estimation pipelines to determine the source parameters of such eccentric systems. We create a set of simulated signals with eccentricity up to 0.3 and find that as the eccentricity increases, the recovered mass parameters are consistent with those of a binary with up to a $\approx 10\%$ higher chirp mass and mass ratio closer to unity. We also employ a full inspiral-merger-ringdown waveform model to perform parameter estimation on two gravitational wave events, GW151226 and GW170608, to investigate this bias on real data. We find that the correlation between the masses and eccentricity persists in real data, but that there is also a correlation between the measured eccentricity and effective spin. In particular, using a nonspinning prior results in a spurious eccentricity measurement for GW151226 as it exhibits signs of nonzero black-hole spin. Performing parameter estimation with an aligned spin, eccentric model, we constrain the eccentricities of GW151226 and GW170608 to be $<0.15$ and $<0.12$ respectively.