We demonstrate the feasibility of ground state preparation for the transverse Ising model using projective cooling, and show that the algorithm can effectively construct the ground state in the disordered (paramagnetic) phase. On the other hand, significant temperature effects are encountered in the ordered (ferromagnetic) phase requiring larger lattices to accurately simulate.

Two-dimensional conformal field theories with just Virasoro symmetry are endowed with integrable structure. We review how to construct the integrable charges in a two-dimensional conformal field theory and how to relate them to the charges of quantum sinh-Gordon theory when $c\ge 25$. We then explicitly calculate the single charge characters in the large $c$ limit for all charges and thereby reveal how their degeneracies grow within one module. This, in particular, allows us to approximate the characters in the limit of small chemical potential, which source the respective charges. The latter gives us insights into possible transformation properties of the characters. We also comment on the full generalized Gibbs ensemble and approximations to pure states.

We prove a nonperturbative duality concerning the dynamics of harmonic-oscillator-type Unruh-DeWitt detectors in curved spacetimes. Concretely, using the Takagi transformation we show that the action of a harmonic oscillator Unruh-DeWitt detector with one frequency in a spacetime is equal to that of a detector with a different frequency in a conformally related spacetime. As an example, we show that the dynamics of simple stationary detectors in flat spacetime is dual to that of detectors in a cosmological scenario. The nonperturbative duality enables us to investigate entanglement harvesting in new scenarios in curved spacetime by using results obtained in simpler, conformally related spacetimes.

We discuss the field quantization of a free massive Dirac fermion in the two causally disconnected static patches of the de Sitter spacetime, by using mode functions that are normalizable on the cosmological event horizon. Using this, we compute the entanglement entropy of the vacuum state corresponding to these two regions, for a given fermionic mode. Further extensions of this result to more general static spherically symmetric and stationary axisymmetric spacetimes are discussed. For the stationary axisymmetric Kerr-de Sitter spacetime in particular, the variations of the entanglement entropy with respect to various eigenvalues and spacetime parameters are depicted numerically. We also comment on such variations when instead we consider the nonextremal black hole event horizon of the same spacetime.

We consider the Einstein-scalar-Gauss-Bonnet theory, and study the case where a negative cosmological constant is replaced by a more realistic, negative scalar-field potential. We study different forms of the coupling function between the scalar field and the Gauss-Bonnet term as well as of the scalar potential. In all cases, we obtain asymptotically flat, regular black-hole solutions with a nontrivial scalar field which naturally dies out at large distances. For a quadratic negative potential, two distinct subgroups of solutions emerge: the first comprises light black holes with a large horizon radius, and the second includes massive, ultracompact black holes. The most ultracompact solutions, having approximately $1/20$ of the horizon radius of the Schwarzschild solution with the same mass, emerge for the exponential and linear coupling functions. For other polynomial forms of the scalar potential, the subgroup of ultracompact solutions disappears, and the black holes obtained may have a horizon radius larger or smaller than the Schwarzschild solution depending on the particular value of their mass.

We use the effective field theory (EFT) framework to compute the mass quadrupole moment, the equation of motion, and the power loss of inspiralling compact binaries at the second order in the post-Newtonian (PN) approximation. We present expressions for the stress-energy pseudotensor components of the binary system in higher PN orders. The 2PN correction to the mass quadrupole moment as well as to the acceleration computed in the linearized harmonic gauge presented here are the ingredients needed for the calculation of the next-to-next-to leading order radiation reaction force, which will be presented elsewhere. While this paper reproduces known results, it supplies the building blocks necessary for future higher order calculations in the EFT methodology.

In the framework of a general scalar-tensor theory, where the scalar field is nonminimally coupled to the five-dimensional Ricci scalar curvature, we investigate the emergence of complete braneworld solutions. By assuming a variety of forms for the coupling function, we solve the field equations in the bulk, and determine in an analytic way the form of the gravitational background and scalar field in each case. The solutions are always characterized by a regular scalar field, a finite energy-momentum tensor, and an exponentially decaying warp factor even in the absence of a negative bulk cosmological constant. The space-time on the brane is described by the Schwarzschild solution leading to either a nonhomogeneous black-string solution in the bulk, when the mass parameter $M$ is nonzero, or a regular anti-de Sitter space-time, when $M=0$. We construct physically acceptable solutions by demanding in addition a positive effective gravitational constant on our brane, a positive total energy density for our brane, and the validity of the weak energy condition in the bulk. We find that, although the theory does not allow for all three conditions to be simultaneously satisfied, a plethora of solutions emerge which satisfy the first two, and most fundamental, conditions.

A new component added to the standard model of cosmology that behaves like a cosmological constant at early times and then dilutes away as radiation or faster can resolve the Hubble tension. We show that a rolling axion coupled to a non-Abelian gauge group exhibits the behavior of such an extra component at the background level and can present a natural particle-physics model solution to the Hubble tension. We compare the contribution of this bottom-up model to the phenomenological fluid approximation and determine that CMB observables sensitive only to the background evolution of the Universe are expected to be similar in both cases, strengthening the case for this model to provide a viable solution to the Hubble tension.

We study gravitational wave production from gauge preheating in a variety of inflationary models, detailing its dependence on both the energy scale and the shape of the potential. We show that preheating into Abelian gauge fields generically leads to a large gravitational wave background that contributes significantly to the effective number of relativistic degrees of freedom in the early universe, $N_{\mathrm{eff}}$. We demonstrate that the efficiency of gravitational wave production is correlated with the tensor-to-scalar ratio, $r$. In particular, we show that efficient gauge preheating in models whose tensor-to-scalar ratio would be detected by next-generation cosmic microwave background experiments ($r\gtrsim 10^{-3}$) will be either detected through its contribution to $N_{\mathrm{eff}}$ or ruled out. Furthermore, we show that bounds on $N_{\mathrm{eff}}$ provide the most sensitive probe of the possible axial coupling of the inflaton to gauge fields regardless of the potential.

We report the detection of new binary black hole merger events in the publicly available data from the second observing run of Advanced LIGO and Advanced Virgo (O2). The mergers were discovered using the new search pipeline described in Venumadhav et al. [Phys. Rev. D 100, 023011 (2019)] and are above the detection thresholds as defined in Abbott et al. (LIGO Scientific and Virgo Collaborations) [Phys. Rev. X 9, 031040 (2019).]. Three of the mergers (GW170121, GW170304, GW170727) have inferred probabilities of being of astrophysical origin $p_{\text{astro}}>0.98$. The remaining three (GW170425, GW170202, GW170403) are less certain, with $p_{\text{astro}}$ ranging from 0.5 to 0.8. The newly found mergers largely share the statistical properties of previously reported events, with the exception of GW170403, the least secure event, which has a highly negative effective spin parameter ${\chi }_{\mathrm{eff}}$. The most secure new event, GW170121 ($p_{\text{astro}}>0.99$), is also notable due to its inferred negative value of ${\chi }_{\mathrm{eff}}$, which is inconsistent with being positive at the $\approx 95.8\%$ confidence level. The new mergers nearly double the sample of gravitational wave events reported from O2 and present a substantial opportunity to explore the statistics of the binary black hole population in the Universe. The number of detected events is not surprising since we estimate that the detection volume of our pipeline may be larger than that of other pipelines by as much as a factor of 2 (with significant uncertainties in the estimate). The increase in volume is larger when the constituent detectors of the network have very different sensitivities, as is likely to be the case in current and future runs.

Weak lensing by large-scale structure is a powerful probe of cosmology and of the dark universe. This cosmic shear technique relies on the accurate measurement of the shapes and redshifts of background galaxies and requires precise control of systematic errors. Monte Carlo control loops (MCCL) is a forward modeling method designed to tackle this problem. It relies on the ultra fast image generator (UFig) to produce simulated images tuned to match the target data statistically, followed by calibrations and tolerance loops. We present the first end-to-end application of this method, on the Dark Energy Survey (DES) Year 1 wide field imaging data. We simultaneously measure the shear power spectrum $C_{\ell }$ and the redshift distribution $n(z)$ of the background galaxy sample. The method includes maps of the systematic sources, point spread function (PSF), an approximate Bayesian computation (ABC) inference of the simulation model parameters, a shear calibration scheme, and a fast method to estimate the covariance matrix. We find a close statistical agreement between the simulations and the DES Y1 data using an array of diagnostics. In a nontomographic setting, we derive a set of $C_{\ell }$ and $n(z)$ curves that encode the cosmic shear measurement, as well as the systematic uncertainty. Following a blinding scheme, we measure the combination of ${\mathrm{\Omega }}_m$, ${\sigma }_8$, and intrinsic alignment amplitude $A_{\mathrm{IA}}$, defined as $S_8{D}_{\mathrm{IA}}={\sigma }_8({\mathrm{\Omega }}_m/0.3{)}^{0.5}{D}_{\mathrm{IA}}$, where $D_{\mathrm{IA}}=1-0.11(A_{\mathrm{IA}}-1)$. We find $S_8{D}_{\mathrm{IA}}=0.895_{-0.039}^{+0.054}$, where systematics are at the level of roughly 60% of the statistical errors. We discuss these results in the context of earlier cosmic shear analyses of the DES Y1 data. Our findings indicate that this method and its fast runtime offer good prospects for cosmic shear measurements with future wide-field surveys.

We present the full color two-loop six-point all-plus Yang-Mills amplitude in compact analytic form. The computation uses four-dimensional unitarity and augmented recursion.

We propose an alternative approach based on series representation to directly reduce multiloop multiscale scattering amplitude into set of freely chosen master integrals. And this approach avoid complicated calculations of inverse matrix and dimension shift for tensor reduction calculation. During this procedure we further utilize the Feynman parameterization to calculate the coefficients of series representation and obtain the form factors. Conventional methodologies are used only for scalar vacuum bubble integrals to finalize the result in series representation form. Finally, we elaborate our approach by presenting the reduction of a typical two-loop amplitude for W boson production.

By combining the Wigner function formalism of relativistic quantum kinetic theory with fundamental equations of relativistic magnetohydrodynamics (MHD), we present a novel approach to determine the proper time evolution of the temperature and other thermodynamic quantities in a uniformly expanding hot, magnetized, and weakly interacting plasma. The aim is to study the contribution of quantum corrections to this evolution. We first determine the corresponding Wigner function in terms of the solution of the Dirac equation in the presence of a constant magnetic field. Using this function, we then compute the energy-momentum tensor of the above-mentioned plasma, which eventually yields its energy density and pressure. Plugging these quantities in the energy equation of relativistic MHD, we arrive, after choosing an appropriate coordinate system, at a differential equation for the temperature as a function of the proper time. The numerical solution of this equation leads finally to the proper time evolution of the temperature. The latter is then used to determine the evolution of a large number of thermodynamic quantities in this expanding and magnetized plasma. We compare our results with other existing results from relativistic MHD. We also comment on the effect of point to point decaying magnetic fields on the thermodynamic properties of this plasma.

The attractive class of higher-dimensional scenarios, based on a brane-localized Higgs boson coupled to bulk fermions, can address both the puzzle of the structure of the flavor space and the gauge hierarchy problem. In this framework, a key question arises due to the possibility of fermion wave function discontinuities at the Higgs boundary: how to build rigorously the Lagrangian and calculate the fermion mass spectrum as well as the effective four-dimensional (4D) Yukawa couplings. We show that the proper treatment, leading to physically consistent solutions, does not rely on any Higgs peak regularization but requires the presence of certain bilinear brane terms. In particular, no profile jump should appear, and the Higgs regularizations turn out to suffer from mathematical discrepancies reflected in two noncommutativities of calculation steps debated in the literature. The introduction of bilinear brane terms can alternatively be replaced by vanishing conditions for probability currents at the considered flat interval boundaries. Indeed, both contribute to the definition of the field geometrical configuration of the model, even in the free case. The bilinear brane terms could allow us to elaborate an ultraviolet origin of the chiral nature of the Standard Model and of its chirality distribution among quarks/leptons. The current conditions are implemented through essential boundary conditions to be contrasted with the natural boundary conditions derived from the action variation. All these theoretical conclusions are confirmed in particular by the converging exact results of the 4D versus five-dimensional approaches. The analysis is completed by a description of the appropriate energy cutoff procedure in the present context. The new calculation methods presented, implying the independence of excited fermion masses and 4D Yukawa couplings on the “wrong-chirality” Yukawa terms, have impacts on phenomenological results like the relaxing of previously obtained strong bounds on Kaluza-Klein masses induced by flavor changing reactions generated via tree-level exchanges of the Higgs field.

In this work, we study the future probes of the complex singlet extension to the standard model (cxSM). This model is possible to realize a strongly first-order electroweak phase transition. The cxSM naturally provides the dark matter candidate, with or without an exact ${\mathbb{Z}}_2$ symmetry in the scalar sector. The benchmark models which can realize the strongly first-order electroweak phase transition are selected and passed to the current observational constraints to the dark matter candidates, including the relic densities and the direct detection limits set by the latest XENON1T results. We then calculate the one-loop corrections to the SM-like Higgs boson decays and the precision electroweak parameters due to the cxSM scalar sector. We perform a global fit to the benchmark models and study the extent to which they can be probed by the future high-energy $e^{+}{e}^{-}$ colliders, such as Circular Electron Positron Collider and Future Circular Collider. Besides, the gravitational wave signals generated by the benchmark models are also evaluated. We further find that the future gravitational wave detector, such as LISA, is complementary in probing the benchmark models that are beyond the sensitivity of the future precision tests at the $e^{+}{e}^{-}$ colliders.

The MiniBooNE Collaboration has reported an excess of $460.5\pm 99.0$ electronlike events ($4.8\sigma$). We propose an explanation of these events in terms of a sterile neutrino decaying into a photon and a light neutrino. The sterile neutrino has a mass around 250 MeV, and it is produced from kaon decays in the proton beam target via mixing with the muon or the electron in the range ${10}^{-11}\lesssim |U_{\ell 4}{|}^2\lesssim {10}^{-7}$ ($\ell =e$, $\mu$). The model can be tested by considering the time distribution of the events in MiniBooNE and by looking for single-photon events in running or upcoming neutrino experiments, in particular by the suite of liquid argon detectors in the short-baseline neutrino program at Fermilab.

We perform lattice studies of meson mass spectra and decay constants of the $Sp(4)$ gauge theory in the quenched approximation. We consider two species of (Dirac) fermions as matter field content, transforming in the 2-index antisymmetric and the fundamental representation of the gauge group, respectively. All matter fields are formulated as Wilson fermions. We extrapolate to the continuum and massless limits and compare to each other the results obtained for the two species of mesons. In the case of two fundamental and three antisymmetric fermions, the long-distance dynamics is relevant for composite Higgs models. This is the first lattice study of this class of theories. The global $SU(4)\times SU(6)$ symmetry is broken to the $Sp(4)\times SO(6)$ subgroup, and the condensates align with the explicit mass terms present in the lattice formulation of the theory. The main results of our quenched calculations are that, with fermions in the 2-index antisymmetric representation of the group, the masses squared and decay constant squared of all the mesons we considered are larger than the corresponding quantities for the fundamental representation, by factors that vary between $\sim 1.2$ and $\sim 2.7$. We also present technical results that will be useful for future lattice investigations of dynamical simulations, of composite chimera baryons, and of the approach to large $N$ in the $Sp(2N)$ theories considered. We briefly discuss their high-temperature behavior, where symmetry restoration and enhancement are expected.

An effective action for “soft” gluons has been constructed by integrating out hard thermal modes of topologically massive vector bosons at one loop order. The gluons are equally massive in the non-Abelian topologically massive model due to a quadratic coupling $B\wedge F$ where a 2-form field $B$ is coupled quadratically with the field strength $F$ of the Yang-Mills (YM) field. This non-Abelian model provides the same asymptotic freedom of strong coupling which is found in massless YM theory at zero temperature. The presence of a gauge-invariant infrared cutoff plays the role of magnetic mass. Thus, in the model, it can be used to get the transport coefficients in the perturbative regime.

Neutrino-nucleus cross section uncertainties are expected to be a dominant systematic in future accelerator neutrino experiments. The cross sections are determined by the linear response of the nucleus to the weak interactions of the neutrino, and are dominated by energy and distance scales of the order of the separation between nucleons in the nucleus. These response functions are potentially an important early physics application of quantum computers. Here we present an analysis of the resources required and their expected scaling for scattering cross section calculations. The current estimates of Trotter steps needed to achieve an energy resolution of 10 MeV and the number of CNOT gates for analyzing ${}^{40}\mathrm{Ar}$ highlights the need for significant improvements in algorithms. We also examine simple small-scale neutrino-nucleus models on modern quantum hardware. In this paper, we use variational methods to obtain the ground state of a three nucleon system (the triton) and then implement the relevant time evolution. To tame the errors in present-day NISQ devices, we explore the use of different error-mitigation techniques to increase the fidelity of the calculations.