Senjanović and Tello have analyzed how one could determine the neutrino Dirac mass matrix in the minimal left-right model, assuming that the mass matrices for the light and heavy neutrinos could be taken as inputs. They provided an analytical solution for the Dirac mass matrix in the case that the left-right symmetry is implemented via a generalized parity symmetry and that this symmetry remains unbroken in the Dirac-Yukawa sector. We extend the work of Senjanović and Tello to the case in which the generalized parity symmetry is broken in the Dirac-Yukawa sector. In this case, the elegant method outlined by Senjanović and Tello breaks down and we need to adopt a numerical approach. Several iterative approaches are described; these are found to work in some cases but to be highly unstable in others. A stable, prescriptive numerical algorithm is described that works in all but a vanishingly small number of cases. We apply this algorithm to numerical datasets that are consistent with current experimental constraints on neutrino masses and mixings. We also provide some additional context and supporting explanations for the case in which the parity symmetry is unbroken.

We describe how recent determinations of exclusive-mode contributions to $a_{\mu }^{\mathrm{LO},\mathrm{HVP}}$, the leading-order hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, can be used to provide, up to small electromagnetic (EM) corrections accessible from the lattice, a data-based dispersive determination of $a_{\mu }^{\text{lqc};\mathrm{IL}}$, the isospin-limit, light-quark-connected contribution to $a_{\mu }^{\mathrm{LO},\mathrm{HVP}}$. Such a determination is of interest in view of the existence of a number of lattice results for this quantity, emerging evidence for a tension between lattice and dispersive determinations of $a_{\mu }^{\mathrm{LO},\mathrm{HVP}}$, and the desire to clarify the source of this tension. Taking as input for the small EM correction that must be applied to the purely data-driven dispersive determination the result $-0.93(58)\times {10}^{-10}$ obtained in a recent BMW lattice study, we find $a_{\mu }^{\text{lqc};\mathrm{IL}}$ to be $635.0(2.7)\times {10}^{-10}$ if the results of Keshavarzi, Nomura, and Teubner are used for the exclusive-mode contributions and $638.4(4.1)\times {10}^{-10}$ if instead those of Davier, Höcker, Malaescu, and Zhang are used.

We provide a complete proof that non-Abelian fermionic $T$ duality along a non-anticommuting Killing spinor always generates a solution to double field theory equations. Examples of non-Abelian fermionic $T$ dualities of string backgrounds with nonvanishing $b$-field are investigated.

We present a universal democratic Lagrangian for the bosonic sector of ten-dimensional type II supergravities, treating “electric” and “magnetic” potentials of all Ramond-Ramond (RR) fields on equal footing. For type IIB, this includes the five-form whose self-duality equation is derived from the Lagrangian. We also present an alternative form of the action for type IIB, with manifest $SL(2,\mathbb{R})$ symmetry.

In this manuscript, we examine the gravitational radiation emitted by binary systems using an Unruh-DeWitt detector coupled to gravitons. Recoil is incorporated into the system via a kinetic energy term in the energy gap of the detector. We find a splitting of the gravitational wave frequency due to the recoil. Implications for the recoil velocity and force are discussed.

Space-borne gravitational-wave (GW) detectors observing at millihertz and decihertz frequencies are expected to detect large numbers of quasimonochromatic signals. The first and second time derivative of the GW frequency (${\dot{f}}_0$ and ${\ddot{f}}_0$) can be measured for the most favorable sources and used to look for negative post-Newtonian corrections, which can be induced by the source’s environment or modifications of general relativity. We present an analytical, Fisher-matrix-based approach to estimate how precisely such corrections can be constrained. We use this method to estimate the bounds attainable on the time evolution of the gravitational constant $G(t)$ with different classes of quasimonochromatic sources observable with LISA and DECIGO, two representative space-borne detectors for millihertz and decihertz GW frequencies. We find that the most constraining source among a simulated population of LISA galactic binaries could yield $\dot{G}/G_0\lesssim {10}^{-6}{\mathrm{yr}}^{-1}$, while the best currently known verification binary will reach $\dot{G}/G_0\lesssim {10}^{-4}{\mathrm{yr}}^{-1}$. We also perform Monte Carlo simulations using quasimonochromatic waveforms to check the validity of our Fisher-matrix approach, as well as inspiralling waveforms to analyse binaries that do not satisfy the quasimonochromatic assumption. We find that our analytical Fisher matrix produces good order-of-magnitude constraints even for sources well beyond its regime of validity. Monte Carlo investigations also show that chirping stellar-mass compact binaries detected by DECIGO-like detectors at cosmological distances of tens of Mpc can yield constraints as tight as $\dot{G}/G_0\lesssim {10}^{-11}{\mathrm{yr}}^{-1}$.

With insight from examples and physical arguments, the Tolman-Ehrenfest criterion of thermal equilibrium for test fluids in static spacetimes is extended to local thermal equilibrium in conformally static geometries. The temperature of the conformally rescaled fluid scales with the inverse of the conformal factor, reproducing the evolution of the cosmic microwave background in Friedmann universes, the Hawking temperature of the Sultana-Dyer cosmological black hole, and a heuristic argument by Dicke.

We study the properties of the Newtonian gravitational potential in a spherical Universe for different topologies. For this, we use the non-Euclidean Newtonian theory developed in Vigneron [On non-Euclidean Newtonian theories and their cosmological backreaction, Classical Quantum Gravity 39, 155006 (2022)]. describing Newtonian gravitation in a spherical or hyperbolic Universe. The potential is calculated for a point mass in all the globally homogeneous regular spherical topologies, i.e., whose fundamental domain is unique and is a platonic solid. We provide the exact solution and the Taylor expansion series of the potential at a test position near the point mass. We show that the odd terms of the expansion can be interpreted as coming from the presence of a nonzero spatial scalar curvature, while the even terms relate to the closed nature of the topological space. A consequence is that, compared to the point mass solution in a 3-torus, widely used in Newtonian cosmological simulations, the spherical cases all feature an additional attractive first order term dependent solely on the spatial curvature. The choice of topology only affects the potential at second order and higher. For typical estimates of cosmological scales (curvature and topology), the strongest topological effect occurs in the case of the Poincaré dodecahedral space, but in general the effect of curvature dominates over topology. We also provide the set of equations that can be used to perform $N$-body simulations of structure formation in spherical topologies.

The redshift drift is computed along light rays propagating through a simulated universe based on the Newtonian $N$-body simulation code gadget-2 combined with a perturbed Friedmann-Lemaitre-Robertson-Walker metric in the Newtonian gauge. It is found that the mean redshift drift is equal to the drift of the mean redshift to the precision of the numerical computations and that this is due to a high degree of cancellation between two dominant components of the redshift drift. This result is contrary to earlier findings based on inhomogeneous cosmological models exhibiting cosmic backreaction. For simplicity, the results neglect contributions from optical drift. Based on a study of the redshift drift in a Lemaitre-Tolman-Bondi model, the optical drift effects are estimated to be at most of order 10% of the redshift drift signal. In addition, it is found that the redshift drift contribution from peculiar acceleration of the emitter is negligible in the simulation setup. However, it is expected that the contribution from peculiar acceleration of the emitter is suppressed in the setup due to low resolution of structures, and it is hence expected that this contribution will be larger for real observations.

Primordial black holes (PBHs) can be not only cold dark matter candidates but also progenitors of binary black holes observed by LIGO-Virgo-KAGRA (LVK) Collaboration. The PBH mass can be shifted to the heavy distribution if multimerger processes occur. In this work, we constrain the merger history of PBH binaries using the gravitational wave events from the third Gravitational-Wave Transient Catalog (GWTC-3). Considering four commonly used PBH mass functions, namely the log-normal, power-law, broken power-law, and critical collapse forms, we find that the multimerger processes make a subdominant contribution to the total merger rate. Therefore, the effect of merger history can be safely ignored when estimating the merger rate of PBH binaries. We also find that GWTC-3 is best fitted by the log-normal form among the four PBH mass functions and confirm that the stellar-mass PBHs cannot dominate cold dark matter.

The effective cold quark matter model by Alford, Braby, Paris, and Reddy (ABPR) is used as a tool for discussing the effect of the size of the pairing gap in three-flavor (CFL) quark matter on the maximum mass of hybrid neutron stars (NSs). This equation of state (EOS) has three parameters which we suggest to determine by comparison with a nonlocal Nambu-Jona-Lasinio (nlNJL) model of quark matter in the nonperturbative domain. We show that due to the momentum dependence of the pairing which is induced by the nonlocality of the interaction, the effective gap parameter in the EOS model is well approximated by a constant value depending on the diquark coupling strength in the Nambu-Jona-Lasinio (NJL) model Lagrangian. For the parameter $a_4=1–2{\alpha }_s/\pi$ a constant value below about 0.4 is needed to explain hybrid stars with ${\mathrm{M}}_{\max }\gtrsim 2.0M_{\odot }$, which would translate to an effective constant ${\alpha }_s\sim 1$. The matching point with a running coupling at the 1-loop $\beta$ function level is found to lie outside the range of chemical potentials accessible in NS interiors. A dictionary is provided for translating the free parameters of the nlNJL model to those of the ABPR model. Both models are shown to be equivalent in the nonperturbative domain but the latter one allows to quantify the transition to the asymptotic behavior in accordance with perturbative QCD. We provide constraints on parameter sets that fulfill the $2M_{\odot }$ mass constraint for hybrid NSs, as well as the low tidal deformability constraint from GW170817 by a softening of the EOS on the hybrid NS branch with an early onset of deconfinement at ${\mathrm{M}}_{\text{onset}}<1.4M_{\odot }$. We find that the effective constant pairing gap should be around 100 MeV but not exceed values of about 130 MeV because a further increase of the gap would entail a softening of the EOS and contradict the $2M_{\odot }$ mass constraint.

In this paper, we extend the Unruh-DeWitt (UDW) model to include a relativistic quantized center of mass (c.m.) for the detector, which traditionally has a classical c.m. and follows a classical trajectory. We develop a relativistic model of an inertial detector following two different approaches, starting from either a first- or second-quantized treatment, which enables us to compare the fundamental differences between the two schemes. In particular, we find that the notion of localization is different between the two models and leads to distinct predictions, which we study by comparing the spontaneous emission rates for the UDW detector interacting with a massless scalar field. Furthermore, we consider the UDW system in both a vacuum and medium and compare our results to existing models describing a classical or quantized c.m. at low energies. We find that the predictions of each model, including the two relativistic cases, can in principle be empirically distinguished, and our results can be further extended to find optimal detector states and processes to perform such experiments. This would clarify both the role of a quantized c.m. for interactions with an external field and the differing localizations between the first- and second-quantized treatments.

We investigate the fluctuations of the net-baryon number density in dense hadronic matter. Chiral dynamics is modeled via the parity doublet Lagrangian, and the mean-field approximation is employed to account for chiral criticality. We focus on the qualitative properties and systematics of the second-order susceptibility of the net-baryon number density for individual positive- and negative-parity nucleons whose masses become degenerate at the chiral restoration. It is shown that the second-order susceptibility of the positive-parity state can become negative when the chiral symmetry is restored, as a natural consequence of the unique relationship of the mass to the order parameter. Moreover, we find that such negative fluctuations are indicative of approaching the critical point on the chiral phase boundary. Our results may have consequences for the interpretation of the experimental data on net-proton fluctuations in heavy-ion collisions.

ATLAS observed a limit for the cross section of dijet resonances, which is weaker than expected for a mass slightly below $\approx 1\mathrm{TeV}$. In addition, CMS reported hints for the (nonresonant) pair production of dijet resonances $X$ via a particle $Y$ at a very similar mass range with a local (global) significance of $3.6\sigma$ ($2.5\sigma$) at $m_X\approx 950\mathrm{GeV}$. In this article, we show that, using the preferred range for $m_X$ from the ATLAS analysis, one can reinterpret the CMS analysis of didijets in terms of a resonant search with $Y\to XX$, with a significantly reduced look-elsewhere effect, finding an excess for $m_Y\approx 3.6\mathrm{TeV}$ with a significance of $4.0\sigma$ ($3.2\sigma$) locally (globally). We present two possible UV completions capable of explaining the (di)dijet excesses, one containing two scalar diquarks, the other one involving heavy gluons based on an $SU(3{)}_1\times SU(3{)}_2\times SU(3{)}_3$ gauge symmetry, spontaneously broken to $SU(3)$ color. In the latter case, nonperturbative couplings are required, pointing toward a composite or extradimensional framework. In fact, using 5D anti–de Sitter space-time, one obtains the correct mass ratio for $m_X/m_Y$, assuming the $X$ is the lowest-lying resonance, and predicts a third (di)dijet resonance with a mass around $\approx 2.2\mathrm{TeV}$.

In Vilenkin’s tunneling wave function proposal our expanding Universe is born via a tunneling through a barrier from nothing at the zero scale factor. We explore the viability of this proposal for the spatially-closed Friedmann-Lemaître-Robertson-Walker model with a positive cosmological constant including quantum gravity modifications in the Planck regime. Our setting is the effective spacetime description of loop quantum cosmology (LQC) which is known to replace the big bang singularity with a bounce due to the holonomy modifications. Due to the bounce, the barrier potential of the Wheeler-DeWitt theory is replaced by a steplike potential which makes the tunneling proposal incompatible. But for a complete picture of singularity resolution, inverse scale-factor modifications from quantum geometry must be included which play an important role at very small scale factors in the spatially closed models. We show that with inclusion of inverse scale-factor modifications the resulting potential is again a barrier potential. The Universe at the vanishing scale factor is dynamically nonsingular and in an Einstein staticlike phase. We show that quantum geometric effects in LQC provide a nonsingular completion of Vilenkin’s tunneling proposal. We also find that quantum geometric effects result in a possibility of a tunneling to a quantum cyclic universe albeit for a very large value of cosmological constant determined by the quantum geometry.

We introduce a decomposition of $D$-dimensional vector amplitudes in terms of building blocks that preserve all partial amplitude relations of the parent gauge theory. Using this decomposition, we derive a new set of amplitude relations between nonlinear sigma model pions and the pure-scalar sector of Yang-Mills scalar theory. These new relations indicate an equivalence between Born-Infeld duality invariance and that of Einstein-Maxwell theory, considering their known double-copy construction from the two scalar theories with Yang-Mills. This observation motivates a general framework for constructing duality-invariant effective field theory observables at any multiplicity using the building blocks in our amplitude decomposition. Finally, we conjecture a subtle relationship between these duality-invariant building blocks and the bosonic sector of $\mathcal{N}=4$ super Yang-Mills.

The problem of finding a vacuum definition for a single quantum field in curved spacetimes is discussed under a new geometrical perspective. The phase space dynamics of the quantum field modes are mapped to curves in a two-dimensional hyperbolic metric space, in which distances between neighbor points are shown to be proportional to the Bogoliubov coefficients associated with their corresponding mode solutions in phase space. The vacuum state for each mode is then defined as the unique trajectory from which all mapped phase space solutions move within thin annular regions around it. This property implies the stability of the vacuum state: solutions evolved from a point in this trajectory stay close to it as both evolve, and the particle creation is therefore minimized. The new approach is applied to the well-known cases of the time-independent dynamics, where the solutions draw circles around this curve, and to the time-dependent dynamics where adiabatic approximation is valid. Additionally, our analysis is extended to more challenging cases of time-dependent dynamics, where the adiabatic approximation is not possible, such as in the super-Hubble or low frequency regimes. It is shown that stability trajectories can also be found in these situations, and stable quantum vacua can be obtained. This new formalism is applied to two situations: de Sitter space, where the Bunch-Davies vacuum is obtained in a completely different manner through an analysis in the super-Hubble regime, and in the context of cosmological bouncing models, in which the contracting phase is dominated by a cosmological constant in the asymptotic past. A new vacuum state for cosmological perturbations is proposed in this situation.

We investigate the effects of short axion kination eras on the energy spectrum of the primordial gravitational waves corresponding to modes that reenter the Hubble horizon at the postelectroweak symmetry breaking epoch well within the radiation domination era. Our main assumption is the existence of an extremely weakly coupled hidden sector between the Higgs and the axion, materialized by higher order nonrenormalizable dimension six and dimension eight operators, active at a scale $M$ of the order 20–100 TeV. This new physics scale $M$, which is way higher than the electroweak scale, is motivated by the lack of new particle observations in the large hadron collider to date beyond the electroweak scale. Once the electroweak symmetry breaking occurs at $T\sim 100\mathrm{GeV}$, the axion potential acquires a new minimum due to the new terms generated by the electroweak breaking, and the axion oscillations at the origin are destabilized. In effect after some considerable amount of time, the axion rolls swiftly to its new minimum, experiencing a short kination epoch, where its energy density redshifts as ${\rho }_a\sim a^{-6}$. After it reaches the new minimum, since the latter is energetically less favorable that the Higgs minimum, it decays to the Higgs minimum and the Universe is described again by the Higgs minimum. The axion returns to the origin and commences again oscillations initiated by quantum fluctuations, redshifts as dark matter, and the same procedure is repeated perpetually. These short axion kination eras may disturb the background total equation of state parameter during the radiation domination era, changing it from that of radiation $w=1/3$ to some value closer to the kination value $w=1$. We examined the effect of a value $w=1/2$ on the energy density of the primordial gravitational waves. As we show, the energy spectrum of the gravitational waves mainly depends on how many times the short axion kination epochs occur, on the inflationary theory, on the actual value of the background equation of state parameter during the short kination eras, and finally on the reheating temperature. Our findings indicate a characteristic shape in the energy spectrum that can be observed in future gravitational wave experiments. We however disregarded the contribution of the electroweak phase transition on the gravitational waves for simplicity and transparency of our results.

We investigate dynamical properties of static and spherically symmetric systems in the self-accelerating branch of the minimal theory of bigravity (MTBG). In the former part, we study the gravitational collapse of pressureless dust and find special solutions, where, in both the physical and fiducial sectors, the exterior and interior spacetime geometries are given by the Schwarzschild spacetimes and the Friedmann-Lemaître-Robertson-Walker universes dominated by pressureless dust, respectively, with specific time slicings. In the case where the Lagrange multipliers are trivial and have no jump across the matter interfaces in both the physical and fiducial sectors, the junction conditions across them remain the same as those in general relativity (GR). For simplicity, we foliate the interior geometry by homogeneous and isotropic spacetimes. For a spatially flat interior universe, we foliate the exterior geometry by a time-independent flat space, while for a spatially curved interior universe, we foliate the exterior geometry by a time-independent space with deficit solid angle. Despite the rather restrictive choice of foliations, we find interesting classes of exact solutions that represent gravitational collapse in MTBG. In the spatially flat case, under a certain tuning of the initial condition, we find exact solutions of matter collapse in which the two sectors evolve independently. In the spatially closed case, once the matter energy densities and the Schwarzschild radii are tuned between the two sectors, we find exact solutions that correspond to the Oppenheimer-Snyder model in GR. In the latter part, we study odd-parity perturbations of the Schwarzschild–de Sitter solutions written in the spatially flat coordinates. For the higher-multipole modes $\ell \ge 2$, we find that, in general, the system reduces to that of four physical modes, where two of them are dynamical and the remaining two are shadowy, i.e., satisfying only elliptic equations. In the case where the ratio of the lapse functions between the physical and fiducial sectors are equal to a constant determined by the parameters of the theory, the two dynamical modes are decoupled from each other, but sourced by one of the shadowy modes. Otherwise, the two dynamical modes are coupled to each other and sourced by the two shadowy modes. At least for the cases of collapse described in this paper, we find that the ratio of the lapse functions is determined by the properties of the collapse itself. On giving appropriate boundary conditions to the shadowy modes so as to not strongly backreact/influence the dynamics of the master variables, in the high frequency and short wavelength limits, we show that the two dynamical modes do not suffer from ghost or gradient instabilities. For the dipolar mode $\ell =1$, the two copies of the slow-rotation limit of the Kerr–de Sitter metrics cannot be a solution in the self-accelerating branch, unless the mass and spin of black holes and effective cosmological constants are tuned to be the same. Therefore, deviation from GR is expected for rotating black holes in the self-accelerating branch of MTBG.

Chern-Simons (CS) gravity is a modified theory of Einstein’s general relativity. The CS theory arises from the low energy limit of string theory which involves anomaly correction to the Einstein-Hilbert action. The CS term is given by the product of the Pontryagin density with a scalar field. In this study, we derive a charged slowly rotating black hole (BH) solution. The main incentives of this BH solution are axisymmetric and stationary and form distortion of the Kerr-Newman BH solution with a dipole scalar field. Additionally, we investigate the asymptotic correction of the metric with the inverse seventh power of the radial distance to the BH solution, This indicates that it will escape any meaningful constraints from weak field experiments. To find this kind of BH by observations, we investigate the propagation of the photon near the BH and we show that the difference between the left-rotated polarization and the right-handed one could be observed as stronger than the case of the Kerr-Newman BH. Finally, we derived the stability condition using the geodesic deviations.