The particle with first-order dynamics proposed by Dunne, Jackiw, and Trugenberger (DJT) to justify the Peierls substitution is obtained by reduction from both of the planar two-parameter centrally extended Galilean and Carroll systems. In the latter case the extension parameters ${\kappa }_{exo}$ and ${\kappa }_{\mathrm{mag}}$ generate noncommutativity of the coordinates resp. behave as an internal magnetic field. The position and momentum follow uncoupled anomalous Hall motions. Consistently with partial immobility, one of the Carroll boost generators is broken but the other remains a symmetry. Switching off ${\kappa }_{exo}$, the immobility of unextended Carroll particles is recovered. The Carroll system is dual to an uncharged anyon on the horizon of a black hole which exhibits the spin-Hall effect. Physical applications are shortly reviewed.

We present a surrogate numerical-relativity model for close hyperbolic black-hole encounters with equal masses and spins aligned with the orbital momentum. Our model, generated in terms of the Newman–Penrose scalar ${\psi }_4$, spans impact parameters $b/M\in [11,15]$ and spin components ${\chi }_i\in [-0.5,0.5]$, modeling the $(\ell ,m)=(2,0)$, $(2,\pm 2)$, $(3,\pm 2)$, and $(4,\pm 4)$ emission multipoles. The model is faithful to numerical-relativity simulations, yielding mismatches lower than ${10}^{-3}$. We test the ability of our model to recover the parameters of numerically simulated signals. We find that, despite the high accuracy of the model, parameter inference struggles to correctly capture the parameters of the source even for SNRs as large as 50 due to the strong degeneracies present in the parameter space. This indicates that correctly identifying these systems will require extremely large signal loudness, which is only typical of third generation detectors. Nevertheless, we also find that, if one attempts to infer certain combinations of such degenerated parameters, there might be a chance to prove the existence of this type of event, even with the current ground-based detectors, as long as these combinations make sense astrophysically and cosmologically.

Galactic double white dwarf (DWD) binaries are among the guaranteed sources for the Laser Interferometer Space Antenna (LISA), an upcoming space-based gravitational wave (GW) detector. Most DWDs in the LISA band are far from merging and emit quasimonochromatic GWs. As these sources are distributed throughout the Milky Way, they experience different accelerations in the Galactic gravitational potential, and therefore each DWD exhibits an apparent GW frequency chirp due to differential acceleration between the source and LISA. We examine how Galactic acceleration influences parameter estimation for these sources; and investigate how LISA observations could provide insight into the distribution of matter in the Galaxy.

We study the decoherence effect of quantum superposition in de Sitter (dS) spacetime due to the presence of the cosmological horizon. Using the algebraic approach of quantum field theory on curved spacetime, we derive the precise expression for the expected number of entangling particles in the scalar field case. This expression establishes the relation between the decoherence and the local two-point correlation function. Specifically, we analyze the quantum superposition Gedankenexperiment performed by a local observer at the center of dS spacetime. We compute the entangling particle numbers in scalar field, electromagnetic field, and gravitational field scenarios. It is demonstrated that the quantum spatial superposition state can be decohered by emitting entangling particles into the cosmological horizon. Our setup is equivalent to an accelerating observer in five-dimensional Minkowski spacetime. The results for the scalar and electromagnetic cases are consistent with those obtained in Wilson-Gerow et al. [Decoherence by warm horizons, Phys. Rev. D 110, 045002 (2024).], which investigated the decoherence effect from the perspective of an accelerating observer in Minkowski spacetime. However, our result fixes the numerical prefactor of the gravitational decoherence.

Superpositions of black holes can be described geometrically using a combined canonical formulation for spacetime and quantum states. A previously introduced black-hole model that includes quantum fluctuations of metric components is shown here to give full access to the corresponding spacetime geometry of weak-field gravity in terms of suitable line elements with quantum corrections. These results can be interpreted as providing covariant formulations of the gravitational force implied by a distribution of black holes in superposition. They can also be understood as a distribution of quantum matter constituents in superposition for a single black hole. A detailed analysis in the weak-field limit reveals quantum corrections to Newton’s potential in generic semiclassical states, as well as new bounds on quantum fluctuations, implied by the covariance condition, rather than the usual uncertainty principle. These results provide additional control on quantum effects in Newton’s potential that can be used in a broad range of predictions to be compared with observations.

Extended gravitational models have gained much attention in the last couple of decades. In this work, we examine the solution space of vacuum, static, and spherically symmetric spacetimes within $F(R)$ theories, introducing novel methods that reduce the vacuum equations to a single second-order equation. For the first time, we derive analytic expressions for the metric functions in terms of the arbitrary functional $F(R)$, providing detailed insight into how the gravitational action impacts the structure of spacetime. We analyze conditions under which solutions are asymptotically flat, regular at the core, and contain an event horizon, obtaining explicit expressions for entropy, temperature, and specific heat in terms of $F(R)$. By using a single metric degree of freedom, we identify the most general solution and examine its (un)physical properties, showing that resolving singularities is not possible within this restricted framework in vacuum. For the general case involving two metric functions, we use several approximation schemes to explore corrections to Schwarzschild–(anti)-de Sitter spacetimes, finding that $F(R)$ extensions to general relativity induce instabilities that are not negligible. Finally, through an analysis of axial perturbations, we derive a general expression for the potential of quasinormal modes of a black hole as a function of the arbitrary Lagrangian.

We examine the performance of the six-parameter $\mathrm{\Lambda }\mathrm{CDM}$ model and its extensions in light of recent cosmological observations, with particular focus on neutrino properties inferred from cosmology. Using a broad suite of nine combinations of datasets, with three separate analyses of the Planck cosmic microwave background (CMB) data, and three separate survey datasets of supernovae (SNe), plus the recent DESI baryon acoustic oscillation (BAO) scale results, we derive constraints on the sum of neutrino masses ($\mathrm{\Sigma }{m}_{\nu }$). Our results show upper limits in the range of $\mathrm{\Sigma }{m}_{\nu }<76.9\mathrm{meV}$ to $\mathrm{\Sigma }{m}_{\nu }<108\mathrm{meV}$ (95% CL). The variation in the limits on $\mathrm{\Sigma }{m}_{\nu }$ arises from the separate analyses of the Planck CMB data and the separate supernova datasets, as they relate to the inferred matter density and its relation to the sensitivity of the BAO scale and CMB lensing to $\mathrm{\Sigma }{m}_{\nu }$. In the context of hierarchical mass models in $\mathrm{\Lambda }\mathrm{CDM}$, we find a $1.47\sigma$ preference for normal ordering (NO) over inverted ordering (IO), with similar values of preference across all datasets. Despite the strong constraints, an inclination toward the nonstandard massless neutrinos over NO remains weak at $1.36\sigma$. We find that a “negative” neutrino mass, inferred from the shape of the likelihood in the physical regime, $\mathrm{\Sigma }{m}_{\nu }>0$, is only present at less than $2\sigma$. The strong $\mathrm{\Sigma }{m}_{\nu }$ constraints originate primarily from the high CMB lensing signal, which disfavors the suppression of power from $\mathrm{\Sigma }{m}_{\nu }$, and the DESI BAO scale, which is complementary to that from the suppression of power. We confirm that models allowing extra relativistic degrees of freedom, with $N_{\mathrm{eff}}\approx 3.5$, alleviate the Hubble tension. Significantly, we find a $3.3\sigma$ preference for a 0.1 eV partially thermalized sterile neutrino when the SH0ES $H_0$ measurement is included, a scale of interest in short-baseline oscillation experiment results. When $H_0$ is included, fully thermalized sterile neutrino models are as consistent as $\mathrm{\Lambda }\mathrm{CDM}$ in fitting all datasets, but are disfavored otherwise. We also explore an 11-parameter model relaxing the dark energy equation of state and curvature, together with $\mathrm{\Sigma }{m}_{\nu }$ and $N_{\mathrm{eff}}$, finding consistency with $\mathrm{\Lambda }\mathrm{CDM}$ parameters except for the dark energy equation of state, $w_0=-0.961_{-0.037}^{+0.012}$. Neutrino mass constraints in this extended model remain stringent, with $\mathrm{\Sigma }{m}_{\nu }<97.0\mathrm{meV}$ (95% CL).

We present constraints on the $f(R)$ gravity model using a sample of 1005 galaxy clusters in the redshift range 0.25–1.78 that have been selected through the thermal Sunyaev-Zel’dovich effect from South Pole Telescope data and subjected to optical and near-infrared confirmation with the multicomponent matched filter algorithm. We employ weak gravitational lensing mass calibration from the Dark Energy Survey Year 3 data for 688 clusters at $z<0.95$ and from the Hubble Space Telescope for 39 clusters with $0.6<z<1.7$. Our cluster sample is a powerful probe of $f(R)$ gravity, because this model predicts a scale-dependent enhancement in the growth of structure, which impacts the halo mass function (HMF) at cluster mass scales. To account for these modified gravity effects on the HMF, our analysis employs a semianalytical approach calibrated with numerical simulations. Combining calibrated cluster counts with primary cosmic microwave background temperature and polarization anisotropy measurements from the Planck 2018 release, we derive robust constraints on the $f(R)$ parameter $f_{R0}$. Our results, ${\log }_{10}|f_{R0}|<-5.32$ at the 95% credible level, are the tightest current constraints on $f(R)$ gravity from cosmological scales. This upper limit rules out $f(R)$-like deviations from general relativity that result in more than a $\sim 20\%$ enhancement of the cluster population on mass scales $M_{200\mathrm{c}}>3\times {10}^{14}{M}_{\odot }$.

Using thermodynamics-gravity conjecture, we present the formal derivation of the modified Friedmann equations inspired by the Barrow entropy, $S\sim A^{1+\delta /2}$, where $0\le \delta \le 1$ is the Barrow exponent and $A$ is the horizon area. We then constrain the exponent $\delta$ by using big-bang nucleosynthesis (BBN) observational data. In order to impose the upper bound on the Barrow exponent $\delta$, we set the observational bound on $|\frac{\delta T_f}{T_f}|$. We find that the Barrow parameter $\delta$ should be around $\delta \simeq 0.01$ in order not to spoil the BBN era. Next we derive the bound on the Barrow exponent $\delta$ in a different approach in which we analyze the effects of Barrow cosmology on the primordial abundances of light elements, i.e., helium ${}^4\mathrm{He}$, deuterium D, and lithium ${}^7\mathrm{Li}$. We observe that the deviation from standard Bekenstein-Hawking expression is small as expected. Additionally, we present the relation between cosmic time $t$ and temperature $T$ in the context of modified Barrow cosmology. We confirm that the temperature of the early Universe increases as the Barrow exponent $\delta$ (fractal structure of the horizon) increases, too.

Polynomial inflation is a simple cosmological scenario, which fits the cosmic microwave background data well. It provides testable predictions for the tensor-to-scalar ratio and the running of the spectral index. In this work, we investigate the production of Dirac dark matter (DM) within the framework of large-field polynomial inflation. We study all relevant production channels including ($i$) nonthermal production through inflaton decays and scatterings, and ($ii$) thermal production from scattering of standard model particles mediated by inflatons and gravitons. In contrast to small-field polynomial inflation, where inflaton decay dominates DM production, we find that graviton-mediated processes can be dominant in the large-field scenario. For DM lighter than the inflaton, we demonstrate that the interplay between graviton- and inflaton-mediated production channels give rise to nontrivial relations between the DM mass and the reheating temperature required to account for the DM relic abundance.

Measurements of the Hubble-Lemaître constant ($H_0$) require us to estimate the distance and recession velocity of galaxies independently. Gravitational clustering that leads to the formation of galaxies and the large-scale structure leaves its imprints in the form of peculiar velocities of galaxies. In general, it is not possible to disentangle the peculiar velocity component from the recession velocities of galaxies, and this introduces an uncertainty in the determination of $H_0$. We use cosmological N-body simulations to quantify the impact of peculiar velocities on the estimation of $H_0$. We consider observers to be located in dark matter halos and target galaxies to be distributed amongst dark matter halos. We compute the distribution of the estimated value of $H_0$ across all such observers in the simulation, and we study the distribution as a function of distance from the observer. We find that the dispersion of this distribution is large at small scales, and it diminishes as we go to large separations, reaching the level of the quoted statistical error in Planck and SH0ES measurements well beyond $\sim 135$ and $\sim 220\mathrm{Mpc}/\mathrm{h}$, respectively. Measurements at smaller scales are susceptible to errors arising from peculiar motions, and this error can propagate to measurements at larger scales in the distance ladder. Notably, we observe a negative correlation between the local overdensity around an observer and the deviation of the local and the global value of $H_0$. We show that deviations more significant than 5% of the global values can be encountered frequently at scales of up to 40 Mpc/h, and this is considerably larger than the statistical errors on local estimates. We also analyze the cumulative effect of such errors on mock measurements of $H_0$ as measured from Milky Way–sized halos. We find that this error is sensitive to the lowest distance at which we use measurements. The distribution of $H_0$ in mock measurements has a large tail, and deviations of a few percent from the global value cannot be ruled out.

Early dark energy (EDE) is one of the leading models proposed to resolve the perplexing Hubble tension. Despite extensive scrutiny and testing against various observables, conclusive constraints remain elusive as we await new data. In this paper, we study the impact of EDE on the 21-cm signal, a powerful probe of cosmic dawn, and the epoch of reionization. First, we examine the signatures of the shift in cosmological parameters and the new EDE parameters on the evolution of the 21-cm signal compared to $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$). We then focus on the implications of these signatures for upcoming radio interferometer telescopes, such as the Hydrogen Epoch of Reionization Array (HERA), and their ability to differentiate between EDE and $\mathrm{\Lambda }\mathrm{CDM}$. Finally, we forecast HERA’s sensitivity to the fractional energy density of EDE, $f_{\mathrm{EDE}}$, assuming a fiducial EDE model. We find significant modifications to the 21-cm signal due to the presence of EDE. Furthermore, our analysis suggests that HERA, operating in its designed configuration, is poised to differentiate between the models and be sensitive to $f_{\mathrm{EDE}}$ within $2\sigma$ after $\mathcal{O}(100)\mathrm{days}$ of observation and $5\sigma$ after two years.

We propose a new mechanism for isotropic cosmic birefringence with an axionlike field that rapidly oscillates during the recombination epoch. In conventional models, the field oscillation during the recombination epoch leads to a cancellation of the birefringence effect and significantly suppresses the EB spectrum of the cosmic microwave background (CMB) polarization. By introducing an asymmetric potential to the axion, this cancellation becomes incomplete, and a substantial EB spectrum can be produced. This mechanism also results in a washout of the EE spectrum, which can be probed in future CMB observations. Our findings suggest the possibility that an axionlike field responsible for isotropic cosmic birefringence can also account for a significant fraction of dark matter.

The search for gravitational waves generated by the inspiral phase of binaries of light compact objects holds significant promise in testing the existence of primordial black holes and/or other exotic objects. In this paper, we present a new method to detect such signals exploiting some techniques typically applied in searches for continuous quasimonochromatic gravitational waves. We describe the signal model employed and present a new strategy to optimally construct the search grid over the parameter space investigated, significantly reducing the search computing cost. Additionally, we estimate the pipeline sensitivity corroborating the results with software injections in real data from the LIGO third observing run. The results show that the method is well suited to detect long-transient signals and standard continuous gravitational waves. According to the criteria used in the grid construction step, the method can be implemented to cover a wide parameter space with slightly reduced sensitivity and lower computational cost or to focus on a narrower parameter space with increased sensitivity at a higher computational expense. The method shows an astrophysical reach up to the Galactic Center (8 kpc) for some regions of the parameter space and given search configurations.

Coherence, which represents the superposition of orthogonal states, is a fundamental concept in quantum mechanics and can also be precisely defined within quantum resource theory. Thus exploring quantum coherence in neutrino oscillations can not only help in examining the intrinsic quantum nature but can also explore their potential applications in quantum information technologies. Previous studies on quantum coherence have focused on neutrino flavor oscillations (FO). However, FO imply that neutrinos have mass, and this can lead to the generation of a tiny but finite magnetic dipole moment of neutrinos through quantum loop diagrams at higher orders of perturbative expansion of the interaction. This electromagnetic property of neutrinos can induce spin flavor oscillations (SFO) in the presence of an external magnetic field and hence is expected to enrich the study of coherence. In this work, we investigate quantum coherence in neutrino SFO with three flavor mixing within the interstellar as well as intergalactic magnetic fields, quantified by the $l_1$ norm and the relative entropy of coherence, and express these measures in terms of neutrino SFO probabilities. For FO, coherence measures can sustain higher values (say, within 50% of the maximum) over distances of several kilometers, which are relevant for terrestrial experiments like reactor and accelerator neutrinos. However, for SFO, we find that the coherence scale can extend to astrophysical distances, spanning from kiloparsecs to gigaparsecs.

We have derived the Wigner equations at global equilibrium with constant vorticity but spacetime dependent electromagnetic fields up to second order in a semiclassical expansion. We obtain the new second-order contributions to the charge currents and energy-momentum tensor from the varying electromagnetic fields. We also compute the new corrections to the spin polarization pesudovector from both constant and varying electromagnetic fields. We also find that the spacetime dependent electromagnetic field provides a tighter constraint on the solutions of Wigner functions in global equilibrium compared with a constant electromagnetic field.

We present a methodology for performing scans of beyond the standard model (BSM) parameter spaces with reinforcement learning. We identify a novel procedure using graph neural networks that is capable of exploring spaces of models without the user specifying a fixed particle content, allowing broad classes of BSM models to be explored—in theory, the technique is applicable to nearly any model space with a prespecified gauge group. We provide a generic procedure by which a suitable graph grammar can be developed for any BSM model that features user-specified symmetry groups and a finite number of different possible particle species, the use of which is applicable to a variety of machine learning tasks over the actions of BSM theories beyond our particular reinforcement learning use case. As a proof of concept, we construct the graph grammar for theories with vectorlike leptons that may or may not be charged under a dark $U(1)$ group, inspired by portal matter extensions of the sub-GeV vector portal/kinetic mixing simplified dark matter models. We then use this graph grammar to create a reinforcement learning environment tasked with creating models with these vectorlike leptons that are consistent with a list of a variety of precision observables. The reinforcement learning agent succeeds in developing models that can address the observed muon anomalous magnetic moment discrepancy while remaining consistent with flavor violation and electroweak precision observables, including both constructions that have previously been studied as well as new models that have not, to our knowledge, previously been identified. By inspecting the resulting ensembles of models that the agent produces and experimenting with different configurations for our reinforcement learning environment and graph grammar, we also infer various lessons about the development of these environments that can be transferable to reinforcement learning scans of more complicated model spaces and comment on future directions for the development of this technique into a more mature tool.

One of the most straightforward extensions of the standard model (SM) is having an additional Higgs doublet to the SM, namely the two-Higgs-doublet models. In the type-I model, an additional Higgs doublet is introduced that does not couple to any fermion via the Yukawa interaction in the original Lagrangian. Considering various theoretical and phenomenological constraints, we have found the best-fitted parameter set in the type-I model using the minimum ${\chi }^2$ method by scanning the model’s parameter space. We show that this optimal parameter set can be tested by precisely analyzing the decay processes $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$, $D^{+}\to {\mu }^{+}{\nu }_{\mu }$, and $B^0\to K^{*}{\mu }^{+}{\mu }^{-}$. Moreover, the decay channels $h\to \gamma \gamma$ and $Z\gamma$ can be used to distinguish the model from the SM. For a direct search of the model at future colliders, we have proposed an investigation of the $e^{+}{e}^{-}\to t\overline{t}b\overline{b}$ process at the International Linear Collider to detect the new physics of the model. Considering the initial state radiation correction and applying appropriate background cuts, the calculation result of the scattering cross section shows that it is feasible to observe a clear and unique signal in the $t\overline{b}$ invariant mass distribution corresponding to the charged Higgs pair creations.

Hamiltonian moments in Fourier space—expectation values of the unitary evolution operator under a Hamiltonian at different times—provide a convenient framework to understand quantum systems. They offer insights into the energy distribution, higher-order dynamics, response functions, correlation information, and physical properties. This paper focuses on the computation of Fourier moments within the context of a nuclear effective field theory on superconducting quantum hardware. The study integrates echo verification and noise renormalization into Hadamard tests using control reversal gates. These techniques, combined with purification and error suppression methods, effectively address quantum hardware decoherence. The analysis, conducted using noise models, reveals a significant reduction in noise strength by two orders of magnitude. Moreover, quantum circuits involving up to 266 cnot gates over five qubits demonstrate high accuracy under these methodologies when run on IBM superconducting quantum devices.

We develop an approach for calculating heavy quark effective theory (HQET) light-cone distribution amplitudes (LCDAs) by employing a sequential effective theory methodology. The theoretical foundation of the framework is established, elucidating how the quasidistribution amplitudes (quasi-DAs) with three scales can be utilized to compute HQET LCDAs. We provide theoretical support for this approach by demonstrating the rationale behind devising a hierarchical ordering for the three involved scales, discussing the factorization at each step, clarifying the underlying reason for obtaining HQET LCDAs in the final phase, and addressing potential theoretical challenges. The lattice QCD simulation aspect is explored in detail, and the computations of quasi-DAs are presented. We employ three fitting strategies to handle contributions from excited states and extract the bare matrix elements. For renormalization purposes, we apply hybrid renormalization schemes at short and long distance separations. To mitigate long-distance perturbations, we perform an extrapolation in $\lambda =z·P^z$ and assess the stability against various parameters. After two-step matching, our results for HQET LCDAs are found in agreement with existing model parametrizations. The potential phenomenological implications of the results are discussed, shedding light on how these findings could impact our understanding of the strong interaction dynamics and physics beyond the standard model. It should be noted, however, that systematic uncertainties have not been accounted for yet.