In the present work, we consider nuclear matter in the innermost crust of neutron stars under the presence of a strong magnetic field within the framework of a relativistic mean-field description. Two models with a different slope of the symmetry energy are considered in order to discuss the density dependence of the equation of state on the crust structure. The nonhomogeneous matter in $\beta$ equilibrium is described within the coexisting phases method, and the effect of including the anomalous magnetic moment is discussed. Five different geometries for the pasta structures are considered. It is shown that strong magnetic fields cause an extension of the inner crust of the neutron stars, with the occurrence of a series of disconnected nonhomogeneous matter regions above the one existing for a null magnetic field. Moreover, we observed that in these disconnected regions, for some values of the magnetic field, all five different cluster geometrical shapes occur, and the gas density is close to the cluster density. Also, the pressure at the neutron star crust-core transition is much larger than the pressure obtained for a zero magnetic field. Another noticeable effect of the presence of strong magnetic fields is the increase of the proton fraction, favoring the appearance of protons in the gas background.

We investigate the dynamics of particles in a Kerr metric which describes the gravitational field in a neighborhood of a rotating black hole. After elimination of cyclic coordinates this problem reduces to investigating a Hamiltonian system with 2 degrees of freedom. This system possesses an additional Carter integral quadratic in momenta and hence is integrable by the Liouville-Arnold theorem. A bifurcation diagram is constructed and a classification of the types of trajectories of the system is carried out according to the values of first integrals. In particular, it is shown that there are seven different regions of values of first integrals which differ in the topological type of the integral submanifold. Pro-and-retrograde trajectories of particles are found.

Elusive as dark matter particles are, they are not the only entities that can produce small energy releases deep inside the most sensitive detectors. Cosmogenic and residual radioactivity as well as other factors can produce and slowly accumulate long-living excitations and defect configurations in materials. Unsteady and avalanche-like releases of accumulated energy can limit the dynamic range of detectors and the sensitivity of experiments. This type of mechanism, while not widely discussed in the dark matter and neutrino detectors community, got a lot of attention in discussions about systems with energy flow in the context of nonequilibrium thermodynamic. This paper explores the avalanche hypothesis using published data on low-energy background in detectors and available condensed-matter physics information on excitations, defects, and energetic molecules which can be produced in detector materials and examine ways to use these models to understand the origin of low-energy background in dark matter and other detectors and for suppression of these backgrounds.

Increasing amounts of spent nuclear fuel (SNF) are stored in dry storage casks for prolonged periods of time. To date no effective technology exists to reverify cask contents should this become necessary. We explore the applicability of coherent-elastic neutrino-nucleus scattering (CEvNS) to monitor the content of SNF from dry storage casks. SNF produces neutrinos chiefly from ${}^{90}\mathrm{Sr}$ decays. We compare these results with what can be achieved via inverse beta decay (IBD). We demonstrate that at low nuclear recoil energies CEvNS events rates exceed the IBD event rates by 2–3 orders of magnitude for a given detector mass. We find that a 10 kg argon or germanium detector 3 meters from a fuel cask can detect over 100 events per year if a nuclear recoil threshold under 100 eV can be achieved.

We add nonlinear and state-dependent terms to quantum field theory. We show that the resulting low-energy theory, nonlinear quantum mechanics, is causal, preserves probability and permits a consistent description of the process of measurement. We explore the consequences of such terms and show that nonlinear quantum effects can be observed in macroscopic systems even in the presence of decoherence. We find that current experimental bounds on these nonlinearities are weak and propose several experimental methods to significantly probe these effects. The locally exploitable effects of these nonlinearities have enormous technological implications. For example, they would allow large-scale parallelization of computing (in fact, any other effort) and enable quantum sensing beyond the standard quantum limit. We also expose a fundamental vulnerability of any nonlinear modification of quantum mechanics—these modifications are highly sensitive to cosmic history and their locally exploitable effects can dynamically disappear if the observed universe has a tiny overlap with the overall quantum state of the universe, as is predicted in conventional inflationary cosmology. We identify observables that should persist in this case and discuss opportunities to detect them in cosmic ray experiments, tests of strong field general relativity and current probes of the equation of state of the universe. Nonlinear quantum mechanics also enables novel gravitational phenomena and may open new directions to solve the black hole information problem and to uncover the theory underlying quantum field theory and gravitation.

A puzzling discrepancy exists between the values of the proton charge radius obtained using different experimental techniques: elastic electron-proton scattering and spectroscopy of electronic and muonic hydrogen. The proton radius is defined through the slope of the electric form factor, $G_E(Q^2)$, at zero four-momentum transfer, which is inaccessible in scattering experiments. We propose a novel method for extracting the proton radius from scattering data over a broad $Q^2$ range rather than attempting to directly determine the slope of $G_E$ at $Q^2=0$. This method relates the radius of the proton to its transverse charge density, which is the two-dimensional Fourier transform of the Dirac form factor, $F_1(Q^2)$. We apply our method to reanalyze the extensive data obtained by the A1 Collaboration [J. C. Bernauer et al. Phys. Rev. Lett. 105, 242001 (2010)] and extract a radius value, $r_E=0.889(5{)}_{\mathrm{stat}}(5{)}_{\mathrm{syst}}(4{)}_{\text{model}}\mathrm{fm}$, that is consistent with the original result. We also provide new parametrizations for the Dirac and Pauli form factors and the transverse charge and magnetization densities of the proton. Our reanalysis shows that the proton radius discrepancy cannot be explained by issues with fitting and extrapolating the A1 data to $Q^2=0$.

In this work we show that the proper analysis and interpretation of the experimental data on the multiplicity distributions of charged particles produced in jets measured in the ATLAS experiment at the LHC indicates their sub-Poissonian nature. We also show how, by using the recurrence relations and combinants of these distributions, one can obtain new and otherwise unavailable information contained in them, which may broaden our knowledge of the particle production mechanism.

We determine the valence generalized parton distributions (GPDs) $H_v^q$ and $E_v^q$ with their uncertainties at zero skewness by performing a ${\chi }^2$ analysis of the world electron scattering data considering two-photon exchange corrections. The data include a wide and updated range of the electric and magnetic form factors (FFs) of the proton and neutron. As a result, we find that there are not enough constraints on GPDs $E_v^q$ from FFs data solely though $H_v^q$ are well constrained. By including the new data of the charge and magnetic radius of the nucleon in the analysis, we show that they put new constraints on the final GPDs, especially on $E_v^q$. Moreover, we calculate the gravitational FF $M_2$ and the total angular momentum $J^q$ using the extracted GPDs and compare them with the FFs obtained from the light-cone QCD sum rules (LCSR) and lattice QCD. We show that our results are interestingly in a good consistency with the pure theoretical predictions.

This is the first study on the double-gluon hybrid, which consists of one valence quark and one valence antiquark together with two valence gluons. We concentrate on the one with the exotic quantum number $J^{\mathrm{PC}}=2^{+-}$ that conventional $\overline{q}q$ mesons cannot reach. We apply the QCD sum rule method to evaluate its mass to be ${2.26}_{-0.25}^{+0.20}\mathrm{GeV}$, and study its possible decay patterns. Especially, its three-meson decay patterns are generally not suppressed severely compared to two-meson decay patterns, so the $S$-wave three-meson decay channels $f_1\omega \pi /f_1\rho \pi$ can be useful in identifying its nature, which is of particular importance to the direct test of QCD in the low energy sector.

The most current observational data corroborate the Starobinsky model as one of the strongest candidates in the description of an inflationary regime. Motivated by such success, extensions of the Starobinsky model have been increasingly recurrent in the literature. The theoretical justification for this is well grounded: higher-order gravities arise in high-energy physics in the search for the ultraviolet completeness of general relativity. In this paper, we propose to investigate the inflation due to the extension of the Starobinsky model characterized by the inclusion of the $R^3$ term. We make a complete analysis of the potential and phase space of the model, where we observe the existence of three regions with distinct dynamics for the scalar field. We can establish restrictive limits for the number of $e$-folds through a study of the reheating and by considering the usual couplings of the standard matter fields and gravity. Thereby, we duly confront our model with the observational data from Planck, BICEP3/Keck, and BAO. Finally, we discuss how the inclusion of the cubic term restricts the initial conditions necessary for the occurrence of a physical inflation.

$H_0$ constraints from galaxy surveys are sourced by the geometric properties of two standardizable rulers: the sound horizon scale, $r_s$, and the matter-radiation equality scale, $k_{\mathrm{eq}}$. While most analyses over the past decade have focused on the first scale, recent work has emphasised that the second can provide an independent source of information about the expansion rate of the Universe. In this work, we demonstrate an improved method for performing such a measurement with future galaxy surveys such as Euclid. Previous approaches have avoided $r_s$-based information by removing the prior on the baryon density, and thus the sound-horizon calibration. Here, we present a new method to marginalize over $r_s$; this allows baryon information to be retained, which enables tighter parameter constraints. For a Euclid-like spectroscopic survey, we forecast sound-horizon independent $H_0$ constraints of ${\sigma }_{H_0}=0.7\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ for our method using the equality scale, compared with ${\sigma }_{H_0}=0.5\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ from the sound horizon. Upcoming equality scale $H_0$ measurements thus can be highly competitive, although we caution that the impact of observational systematics on such measurements still needs to be investigated in detail. Applying our new approach to the BOSS power spectrum gives $H_0={69.5}_{-3.5}^{+3.0}\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ from equality alone, somewhat tighter than previous constraints. Consistency of $r_s$- and $k_{\mathrm{eq}}$-based $H_0$ measurements can provide a valuable internal consistency test of the cosmological model; as an example, we consider the change in $H_0$ created by early dark energy. Assuming the $\mathit{Planck}+\mathrm{SH}0\mathrm{ES}$ best-fit early dark energy model we find a $2.6\sigma$ shift ($\mathrm{\Delta }{H}_0=2.6\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$) between the two measurements for Euclid; if we instead assume the ACT best-fit model, this increases to $9.0\sigma$ ($\mathrm{\Delta }{H}_0=7.8\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$).

We present a calculation of the scalar, vector, and tensor form factors for the pion and kaon in lattice QCD. We use an ensemble of two degenerate light, a strange and a charm quark ($N_f=2+1+1$) of maximally twisted mass fermions with clover improvement. The corresponding pion and kaon masses are about 265 MeV and 530 MeV, respectively. The calculation is done in both rest and boosted frames obtaining data for four-vector momentum transfer squared up to $-q^2=2.5{\mathrm{GeV}}^2$ for the pion and $3{\mathrm{GeV}}^2$ for the kaon. The excited-states effects are studied by analyzing six values of the source-sink time separation for the rest frame (1.12–2.23 fm) and for four values for the boosted frame (1.12–1.67 fm). The lattice data are renormalized nonperturbatively and the results for the scheme- and scale-dependent scalar and tensor form factors are presented in the $\overline{\mathrm{MS}}$ scheme at a scale of 2 GeV. We apply different parametrizations to describe $q^2$-dependence of the form factors to extract the scalar, vector, and tensor radii, as well as the tensor anomalous magnetic moment. We compare the pion and kaon form factors to study SU(3) flavor symmetry breaking effects. By combining the data for the vector and tensor form factors we also obtain the lowest moment of the densities of transversely polarized quarks in the impact parameter space. Finally, we give an estimate for the average transverse shift in the $y$ direction for polarized quarks in the $x$ direction.

We perform the manifestly covariant quantization of a scale invariant gravity with a scalar field, which is equivalent to the well-known Brans-Dicke gravity via a field redefinition of the scalar field, in the de Donder gauge condition (or harmonic gauge condition) for general coordinate invariance. First, without specifying the expression of a gravitational theory, we write down various equal-time (anti)commutation relations (ETCRs), in particular, those involving the Nakanishi-Lautrup field, the Faddeev-Popov (FP) ghost, and the FP antighost only on the basis of the de Donder gauge condition. It is shown that choral symmetry, which is a Poincaré-like $IOSp(8|8)$ supersymmetry, can be derived from such a general action with the de Donder gauge. Next, taking the scale invariant gravity with a scalar field as a classical theory, we derive the ETCRs for the gravitational sector involving the metric tensor and scalar fields. Moreover, we account for how scale symmetry is spontaneously broken in quantum gravity, thereby showing that the dilaton is a massless Nambu-Goldstone particle.

We propose a measurement theory for quantum fields based on measurements made with localized nonrelativistic systems that couple covariantly to quantum fields (like the Unruh-DeWitt detector). Concretely, we analyze the positive operator-valued measure induced on the field when an idealized measurement is carried out on the detector after it coupled to the field. Using an information-theoretic approach, we provide a relativistic analogue to the quantum-mechanical Lüders update rule to update the field state following the measurement on the detector. We argue that this proposal has all the desirable characteristics of a proper measurement theory. In particular it does not suffer from the “impossible measurements” problem pointed out by Rafael Sorkin in the 1990s which shows that idealized measurements cannot be used in quantum field theory.

Feynman diagrams for gluon tree amplitudes are studied in the Feynman gauge and in any number of spacetime dimensions. The color-kinematics combinations $\mathrm{\Delta }=n_s-n_t-n_u$ of numerators are explicitly calculated for $N=4$, 5, 6 gluons to see whether the color-kinematics relation $\mathrm{\Delta }=0$ is satisfied. This is a tedious task because of the presence of four-gluon vertices, and the large number of Feynman diagrams, numerators, and $\mathrm{\Delta }$ combinations involved, especially when $N=6$. For on-shell amplitudes, it is found that $\mathrm{\Delta }=0$ for $N=4$, but $\mathrm{\Delta }\ne 0$ for $N=5$ and $N=6$ owing to the presence of the four-gluon vertex. However, a local generalized gauge transformation can bring about $\mathrm{\Delta }=0$ for $N=5$, but not for $N=6$. This raises the question whether gluon amplitudes satisfying the color-kinematics relation contain nonlocal interactions.

Detection of many compact binary coalescences (CBCs) is one of the primary goals of the present and future ground-based gravitational-wave (GW) detectors. While increasing the detectors’ sensitivities will be crucial in achieving this, efficient data analysis strategies can play a vital role. With given computational power in hand, efficient data analysis techniques can expand the size and dimensionality of the parameter space to search for a variety of GW sources. Matched filtering-based analyses that depend on modeled signals to produce adequate signal-to-noise ratios for signal detection may miss them if the parameter space is too restrained. Specifically, the CBC search is currently limited to nonprecessing binaries only, where the spins of the components are either aligned or antialigned to the orbital angular momentum. A hierarchical search for CBCs is thus well motivated. The first stage of this search is performed by matched filtering coarsely sampled data with a coarse template bank to look for candidate events. These candidates are then followed up for a finer search around the vicinity of an event’s parameter space found in the first stage. Performing such a search leads to enormous savings in the computational cost without much loss in sensitivity. Here we report the first successful implementation of the hierarchical search as a pycbc-based production pipeline to perform a complete analysis of Laser Interferometer Gravitational Wave Observatory (LIGO) observing runs. With this, we analyze Advanced LIGO’s first and second observing run data. We recover all the events detected by the pycbc (flat) search in the first GW catalog, GWTC-1, published by the LIGO-Virgo collaboration, with nearly the same significance using a scaled background. In the analysis, we get an impressive factor of 20 reduction in computation compared to the flat search. With a standard injection study, we show that the sensitivity of the hierarchical search remains comparable to the flat search within the error bars.

We present a general solution of the coupled Einstein-Maxwell field equations (without the source charges and currents) in three spacetime dimensions. We also admit any value of the cosmological constant. The whole family of such $\mathrm{\Lambda }$-electrovacuum local solutions splits into two distinct subclasses, namely the nonexpanding Kundt class and the expanding Robinson-Trautman class. While the Kundt class only admits electromagnetic fields which are aligned along the geometrically privileged null congruence, the Robinson-Trautman class admits both aligned and also more complex nonaligned Maxwell fields. We derive all the metric and Maxwell field components, together with explicit constraints imposed by the field equations. We also identify the most important special spacetimes of this type, namely the coupled gravitational-electromagnetic waves and charged black holes.