We explore the relationship between the effective dynamics in standard loop quantum cosmology (LQC) based on holonomies and triads obtained from gauge-fixing fluxes, and a modification of LQC based on holonomies and gauge-covariant fluxes (referred to as GLQC). Both the models yield singularity resolution via a bounce because of nonperturbative quantum geometric effects resulting in a maximum for energy density. In LQC, the bounce is extremely well captured by a ${\rho }^2$ term in energy density with a negative sign which emerges as a nonperturbative modification to the classical Friedmann and Raychaudhuri equations. But details of such modifications in GLQC have remained hidden due to an arduous nature of gauge-covariant flux modifications which do not allow writing above equations in a closed form. To extract these modifications we explore the large volume, weak curvature limit for matter with a fixed equation of state and obtain higher order corrections to the classical theory. We find that in the weak curvature limit of GLQC, in the postbounce branch, the first order correction beyond classical theory fully recovers the form of modified Friedmann and Raychaudhuri equations of LQC. In contrast, due to an asymmetric bounce in GLQC, the weak curvature limit of the prebounce branch exhibits a novel structure with a ${\rho }^{3/2}$ term as a first order correction beyond classical theory while the ${\rho }^2$ term appears as a second order correction. Our work shows that GLQC has a far richer structure which includes the form of dynamical equations with nonperturbative modifications in LQC in its weak curvature limit. This indicates that more general loop quantizations of cosmological sectors can reveal LQC at some truncation, and possibly there exists a tower of potentially interesting higher order modifications from quantum geometry which are hidden in the setting of LQC.

In this manuscript we provide a consistent way of describing a localized nonrelativistic quantum system undergoing a timelike trajectory in a background curved spacetime. Namely, using Fermi normal coordinates, we identify an inner product and canonically conjugate position and momentum operators defined in the rest space of the trajectory for each value of its proper time. This framework then naturally provides a recipe for mapping a quantum theory defined in a nonrelativistic background to a theory around a timelike trajectory in curved spacetimes. This is done by reinterpreting the position and momentum operators and by introducing a local redshift factor to the Hamiltonian, which gives rise to new dynamics due to the curvature of spacetime and the acceleration of the trajectory. We then apply our formalism to particle detector models, that is, to the case where the nonrelativistic quantum system is coupled to a quantum field in a curved background. This allows one to write a general definition for particle detector models which is able to recover the previous models in the literature. Our framework also allows one to estimate the regime of validity of these models, characterizing the situations where particle detectors can be used to accurately probe quantum fields.

It is well established that the mass parameter breaks the conformal symmetries in the case of geodesic motion. The proper conformal Killing vectors cease to generate conserved charges when non-null geodesics are considered. We examine how the introduction of the mass is actually related to the appearance of appropriate distortions in the conformal sector, which lead to new conservation laws. As a prominent example, we use a general pp-wave metric, which exploits this property to the maximum. We study the necessary geometric conditions, so that such types of distortions are applicable. We show that the relative vectors are generators of disformal transformations and prove their connection to higher order (hidden) symmetries. Except from the pp-wave geometry, we also provide an additional example in the form of the de Sitter metric. Again, the proper conformal Killing vectors can be appropriately distorted to generate conserved quantities for massive geodesics. Subsequently, we proceed by introducing an additional symmetry breaking effect. The latter is realized by considering a Bogoslovsky type of line element, which involves a Lorentz violating parameter. We utilize once more the pp-wave case as a guide to study how the broken symmetries—this time also related to Killing vectors—are substituted by distortions of the original generators. We further analyze and discuss the necessary geometric conditions that lead to the emergence of these distortions.

Upcoming observational runs of the LIGO-Virgo-KAGRA Collaboration and future gravitational-wave (GW) detectors on the ground and in space require waveform models more accurate than currently available. High-precision waveform models can be developed by improving the analytical description of compact binary dynamics and completing it with numerical-relativity (NR) information. Here, we assess the accuracy of the recent results for the fourth post-Minkowskian (4PM) conservative dynamics through comparisons with NR simulations for the circular-orbit binding energy and for the scattering angle. We obtain that the 4PM dynamics gives better agreement with NR than the 3PM dynamics and that while the 4PM approximation gives comparable results to the third post-Newtonian (PN) approximation for bound orbits it performs better for scattering encounters. Furthermore, we incorporate the 4PM results in effective-one-body (EOB) Hamiltonians, which improves the disagreement with NR over the 4PM-expanded Hamiltonian from $\sim 40\%$ to $\sim 10\%$, or $\sim 3\%$ depending on the EOB gauge, for an equal-mass binary, two GW cycles before merger. Finally, we derive a 4PN-EOB Hamiltonian for hyperbolic orbits and compare its predictions for the scattering angle to NR and to the scattering angle of a 4PN-EOB Hamiltonian computed for elliptic orbits.

We construct $\alpha$-attractor versions of hybrid inflation models. In these models, the potential of the inflaton field $\phi$ is uplifted by the potential of the second field $\chi$. This uplifting ends due to a tachyonic instability with respect to the field $\chi$, which appears when $\phi$ becomes smaller than some critical value ${\phi }_c$. In the large $N$ limit, these models have the standard universal $\alpha$-attractor predictions. In particular, $n_s=1-\frac{2}{N}$ for the exponential attractors. However, in some special cases, the large $N$ limit is reached only beyond the horizon, for $N\gtrsim 60$. This may change predictions for the cosmological observations. For any fixed $N$, in the limit of large uplift $V_{\mathrm{up}}$, or in the limit of large ${\phi }_c$, we find another attractor prediction, $n_s=1$. By changing the parameters, $V_{\mathrm{up}}$ and ${\phi }_c$, one can continuously interpolate between the two attractor predictions $n_s=1-\frac{2}{N}$ and $n_s=1$. This provides significant flexibility, which can be very welcome in view of the rapidly growing amount and precision of the cosmological data. Our main result is not specific to the hybrid inflation models. Rather, it is generic to any inflationary models, where the inflaton potential, for some reason, is uplifted, and inflation ends prematurely.

The spatial distribution of galaxies at sufficiently small scales will encode information about the identity of the dark matter. We develop a novel description of the halo distribution using persistent homology summaries, in which collections of points are decomposed into clusters, loops, and voids. We apply these methods, together with a set of hypothesis tests, to dark matter haloes in Milky Way-analog environment regions of the cold dark matter (CDM) and warm dark matter (WDM) Copernicus Complexio $N$-body cosmological simulations. The results of the hypothesis tests find statistically significant differences (p-values $\le 0.001$) between the CDM and WDM structures, and the functional summaries of persistence diagrams detect differences at scales that are distinct from the comparison spatial point process functional summaries considered (including the two-point correlation function). The differences between the models are driven most strongly at filtration scales $\sim 100\mathrm{kpc}$, where CDM generates larger numbers of unconnected halo clusters while WDM instead generates loops. This study was conducted on dark matter haloes generally; future work will involve applying the same methods to realistic galaxy catalogues.

Strongly lensed type Ia supernovae (SNe Ia) are expected to have some advantages in measuring time delays of multiple images, and so they have a great potential to be developed into a powerful late-Universe cosmological probe. In this paper, we simulate a sample of lensed SNe Ia with time-delay measurements in the era of the Legacy Survey of Space and Time (LSST). Based on the distance sum rule, we use lensed SNe Ia to implement cosmological model-independent constraints on the Hubble constant $H_0$ and cosmic curvature parameter ${\mathrm{\Omega }}_K$ in the late Universe. We find that if 20 lensed SNe Ia could be observed, the constraint on $H_0$ is better than the measurement by the SH0ES Collaboration. When the event number of lensed SNe Ia increases to 100, the constraint precision of $H_0$ is comparable with the result from Planck 2018 data. Considering 200 lensed SNe Ia events as the optimistic estimation, we obtain $\mathrm{\Delta }{H}_0=0.33\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ and $\mathrm{\Delta }{\mathrm{\Omega }}_K=0.053$. In addition, we also simulate lensed quasars in different scenarios to make a comparison and we find that they are still a useful cosmological probe even though the constraint precision from them is much less than that obtained from lensed SNe Ia. In the era of LSST, the measurements of time delay from both lensed SNe Ia and lensed quasars are expected to yield the results of $\mathrm{\Delta }{H}_0=0.26\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ and $\mathrm{\Delta }{\mathrm{\Omega }}_K=0.044$.

In the scalar field dark matter model virialized halos present condensed central cores called boson stars. Considering the equivalent process during reheating, we look at the formation of primordial black holes (PBHs) through the gravitational collapse of structures virialized in this era. We present the criteria necessary for collapse of either the whole structure, or that of the central core, in terms of the threshold amplitude for the primordial density contrast. This is computed for both the free and the self-interacting scalar fields. We discuss the relevance of our results for the abundance of PBHs.

In this work, we study quantum fluctuations in the stress energy tensor of spinor fields evolving in general Friedmann-Robertson-Walker (FRW) spacetimes. We quantify these fluctuations by the noise kernel of spinor fields. For the particular case of de Sitter spacetime, we place the spinor field in what is called the fermionic Bunch Davies vacuum and study the variation of the noise kernel with the mass of the field. We then make use of the conformal invariance of massless spinor fields and employ an equivalence that relates a massless spinor field in any given FRW spacetime with a corresponding massless spinor field in de Sitter spacetime. Using this equivalence, we study the behavior of the noise kernel of massless spinor fields in general FRW spacetimes while placing the fields in the Bunch Davies vacuum of the corresponding massless spinor field of the de Sitter spacetime. We extend this analysis to a coordinate invariant quantity which is built from the noise kernel of the field. We compare these results for spinor fields in considered spacetimes with the analogous results for scalar fields. This study helps us better understand whether the spin $1/2$ fermionic matter remains strongly correlated in considered spacetimes leading to considerable backreaction or not.

We study the amplification of the curvature perturbations due to a small sound speed and find that its origin is different completely from that due to the ultraslow-roll inflation. This is because when the sound speed is very small the enhancement of the power spectrum comes from the fact that the curvature perturbations at the scales smaller than the cosmic microwave background (CMB) scale become scale variant, rather than growing that leads to the amplification of the curvature perturbations during the ultraslow-roll inflation. At large scales, the power spectrum of the curvature perturbations remains to be scale invariant, which is consistent with the CMB observations, and then it will have a transient $k^2$ growth and finally approach a $k^4$ growth as the scale becomes smaller and smaller. Thus, the power spectrum can be enhanced to generate a sizable amount of primordial black holes. Furthermore, when the high order correction in the dispersion relation of the curvature perturbations is considered, the growth of the power spectrum of the curvature perturbations has the same origin as that in the case without this correction.

If dark matter annihilates with a velocity-dependent cross section within a subhalo, then the magnitude and angular distribution of the resulting photon signal will change. These effects are encoded in the $J$-factor. In this work we compute the $J$-factor for a variety of choices for the cross section velocity dependence, and for a variety of choices for the dark matter profile, including generalized Navarro-Frenk-White, Einasto, Burkert and Moore. Interestingly, we find that for a density profile with an inner slope power law steeper than $4/3$, Sommerfeld-enhanced annihilation in the Coulomb limit leads to a divergence at the center, requiring a more detailed treatment of departure from the Coulomb limit.

The sources of the majority of the high-energy astrophysical neutrinos observed with the IceCube neutrino telescope at the South Pole are unknown. So far, only a flaring gamma-ray blazar was compellingly associated with the emission of high-energy neutrinos. However, several studies suggest that the neutrino emission from the gamma-ray blazar population only accounts for a small fraction of the total astrophysical neutrino flux. In this work we probe the production of high-energy neutrinos in the cores of active galactic nuclei (AGN), induced by accelerated cosmic rays in the accretion disk region. We present a likelihood analysis based on eight years of IceCube data, searching for a cumulative neutrino signal from three AGN samples created for this work. The neutrino emission is assumed to be proportional to the accretion disk luminosity estimated from the soft x-ray flux. Next to the observed soft x-ray flux, the objects for the three samples have been selected based on their radio emission and infrared color properties. For the largest sample in this search, an excess of high-energy neutrino events with respect to an isotropic background of atmospheric and astrophysical neutrinos is found, corresponding to a post-trial significance of $2.60\sigma$. If interpreted as a genuine signal with the assumptions of a proportionality of x-ray and neutrino fluxes and a model for the subthreshold flux distribution, then this observation implies that at 100 TeV, 27%–100% of the observed neutrinos arise from particle acceleration in the core of AGN at $1\sigma$ confidence interval.

The Laser Interferometer Space Antenna (LISA) mission aims to observe gravitational waves featuring a three-spacecraft interferometer constellation with an arm length of 2.5 Mio km. In support of maximizing LISA’s scientific return, the paper presents the design of coordinated spacecraft constellation maneuvers tailored for high-precision estimation of tilt-to-length (TTL) coupling noise under the influence of gravitational wave events. Tilt-to-length coupling couples the angular jitter of the three LISA spacecraft and their optomechanical assemblies to longitudinal measurement noise of the interferometers. The effect is a fundamental limitation of LISA’s sensitivity and spaceborne long-arm interferometers, in general. The limitation can be avoided by estimating tilt-to-length coupling noise and correcting the scientific measurements. Former research allows limited conclusions to be drawn about the feasibility of accurate tilt-to-length coupling estimation because only the effect of system-internal noise sources has been addressed. Since tilt-to-length coupling noise in LISA is estimated and corrected based on science instrument measurements, the calibration shall be robust against the disturbing impact of gravitational wave events. The paper quantifies the deterioration of tilt-to-length parameter observabilities in the view of stellar and galactic events without maneuver execution. Then the developed maneuver design method is shown to provide accurate estimation results in the more realistic scenario. Although the approach temporarily reduces the number of independent scientific signals, the scientific operation mode of the spacecraft constellation can be maintained.

We implement a comprehensive and detailed study of the alignment of Yukawa couplings in the so-called Higgs basis taking the framework of general two Higgs doublet models (2HDMs). We clarify the model input parameters and derive the Yukawa couplings considering the two types of $CP$-violating sources: One from the Higgs potential and the other from the three complex alignment parameters ${\zeta }_{f=u,d,e}$. We consider the theoretical constraints from the perturbative unitarity and for the Higgs potential to be bounded from below as well as the experimental ones from electroweak precision observables. Also considered are the constraints on the alignment parameters from flavor-changing $\tau$ decays, $Z\to b\overline{b}$, ${\epsilon }_K$, and the radiative $b\to s\gamma$ decay. By introducing the basis-independent Yukawa delay factor ${\mathrm{\Delta }}_{H_1\overline{f}f}\equiv |{\zeta }_f|(1-g_{H_{1}VV}^2{)}^{1/2}$, we scrutinize the alignment of the Yukawa couplings of the lightest Higgs boson to the SM fermions.

In neutrino oscillation physics, numerous exact degeneracies exist under the name LMA-Dark. These degeneracies make it impossible to determine the sign of $\mathrm{\Delta }{m}_{31}^2$, known as the atmospheric mass ordering, with oscillation experiments alone in the presence of new neutrino interactions. The combination of different measurements, including multiple oscillation channels and neutrino scattering experiments, lifts some aspects of these degeneracies. In fact, previous measurements of coherent elastic neutrino nucleus scattering ($\mathrm{CE}\nu \mathrm{NS}$) by COHERENT already ruled out the LMA-Dark solution for new physics with mediators heavier than $M_{Z^{\prime }}\sim 50\mathrm{MeV}$, while cosmological considerations disfavor these scenarios for mediators lighter than $M_{Z^{\prime }}\sim 3\mathrm{MeV}$. Here we leverage new data from the Dresden-II experiment, which provides the strongest bounds on $\mathrm{CE}\nu \mathrm{NS}$ with reactor neutrinos to date. We show that these data completely remove the degeneracies in the ${\nu }_e$ sector for mediators down to the MeV scale, at which point constraints from the early Universe take over. While the LMA-Dark degeneracy is lifted in the ${\nu }_e$ sector, it can still be restored in the ${\nu }_{\mu }$ and ${\nu }_{\tau }$ sectors, or with very specific couplings to up and down quarks, and we speculate on a path forward.

In this article a novel mechanism for dynamical electroweak symmetry breaking and the ensuing appearance of fermion mass terms in the action is proposed. The action contains massless fermions of the standard model coupled to gravity through a new type of nonminimal coupling to the vielbein field. The corresponding coupling constants in our approach become zero-dimension scalar fields. Such scalar fields provide the cancellation of the Weyl anomaly [Latham Boyle and Neil Turok, arXiv:2110.06258].

Inspired by the experimental discoveries of $T_{cc}$, ${\mathrm{\Sigma }}_c(2800)$, and ${\mathrm{\Lambda }}_c(2940)$ and the theoretical picture where they are $D{D}^{*}$, $DN$, and $D^{*}N$ molecular candidates, we investigate the double-charm heptaquark system of $D{D}^{*}N$. We employ the one-boson-exchange model to deduce the pairwise $D\text{−}{D}^{*}$, $D\text{−}N$, and $D^{*}\text{−}N$ potentials and then study the $D{D}^{*}N$ system with the Gaussian expansion method. We find two good hadronic molecular candidates with $I(J^P)=\frac{1}{2}({\frac{1}{2}}^{+})$ and $\frac{1}{2}({\frac{3}{2}}^{+})$ $D{D}^{*}N$ with only $S$-wave pairwise interactions. The conclusion remains unchanged even taking into account the $S\text{−}D$ mixing and coupled channel effects. In addition to providing the binding energies, we also calculate the root-mean-square radii of the $D{D}^{*}N$ system, which further support the molecular nature of the predicted states. They can be searched for at the upcoming LHC run 3 and run 4.

Circular photon orbits and black hole shadows are significantly important issues in physics and astronomy, and a number of breakthroughs have been witnessed in recent years. Conventionally, the stable and unstable circular photon orbits are obtained using the effective potential of test particles moving in black hole spacetime. In this work, a pure geometric approach is developed to calculate these circular photon orbits and black hole shadow radius. Furthermore, it can be proved that our geometric approach is completely equivalent to the conventional approach based on effective potentials of test particles.

From the recently known $\mathcal{N}=2$ supersymmetric linear $W_{\infty }^{K,K}[\lambda ]$ algebra where $K$ is the dimension of the fundamental (or antifundamental) representation of the bifundamental $\beta \gamma$ and $bc$ ghost system, we determine its $\mathcal{N}=4$ supersymmetric enhancement at $K=2$. We construct the $\mathcal{N}=4$ stress energy tensor, the first $\mathcal{N}=4$ multiplet, and their operator product expansions (OPEs) in terms of the above bifundamentals. We show that the OPEs between the first $\mathcal{N}=4$ multiplet and itself are the same as the corresponding ones in the $\mathcal{N}=4$ coset $\frac{SU(N+2)}{SU(N)}$ model under the large $(N,k)$ ’t Hooft–like limit with fixed ${\lambda }_{co}\equiv \frac{(N+1)}{(k+N+2)}$, up to two central terms. The two parameters are related to each other, $\lambda =\frac{1}{2}{\lambda }_{co}$. We also provide other OPEs by considering the second, the third, and the fourth $\mathcal{N}=4$ multiplets in the $\mathcal{N}=4$ supersymmetric linear $W_{\infty }[\lambda ]$ algebra.