The connection between tree-level scattering amplitudes and the Seiberg-Witten (SW) map in the Moyal deformed U(1) noncommutative quantum electrodynamics (NCQED) is studied. We show that in the minimal U(1) NCQED based on a reversible Seiberg-Witten (SW) map, SW map induced interactions cancel each other in all tree-level scattering amplitudes and leave them identical to the Moyal NCQED without SW map. On the other hand, the two-by-two Compton and light-by-light scattering amplitudes deviate from minimal model when irreversible SW map is used. Therefore the reversibility of SW map and equivalence between NCQED before and after SW map manifest as an identity between the tree-level scattering amplitudes.

A topological $\theta$-term in gauge theories, including quantum chromodynamics in $3+1$ dimensions, gives rise to a sign problem that makes classical Monte Carlo simulations impractical. Quantum simulations are not subject to such sign problems and are a promising approach to studying these theories in the future. In the near term, it is interesting to study simpler models that retain some of the physical phenomena of interest and their implementation on quantum hardware. For example, dimensionally reducing gauge theories on small spatial tori produces quantum mechanical models which, despite being relatively simple to solve, retain interesting vacuum and symmetry structures from the parent gauge theories. Here we consider quantum mechanical particle-on-a-circle models, related by dimensional reduction to the $1+1\mathrm{d}$ Schwinger model, that possess a $\theta$-term and realize an ’t Hooft anomaly or global inconsistency at $\theta =\pi$. These models also exhibit the related phenomena of spontaneous symmetry breaking and instanton-anti-instanton interference in real time. We propose an experimental scheme for the real-time simulation of a particle on a circle with a $\theta$-term and a ${\mathbb{Z}}_n$ potential using a synthetic dimension encoded in a Rydberg atom. Simulating the Rydberg atom with realistic experimental parameters, we demonstrate that the essential physics can be well captured by the experiment, with expected behavior in the tunneling rate as a function of $\theta$. Similar phenomena and observables can also arise in more complex quantum mechanical models connected to higher-dimensional non-Abelian gauge theories by dimensional reduction.

Studying QCD and other gauge theories on quantum hardware requires the preparation of physically interesting states. The variational quantum eigensolver provides a way of performing vacuum state preparation on quantum hardware. In this work, variational quantum eigensolver is applied to pure SU(3) lattice Yang-Mills on a single plaquette and one dimensional plaquette chains. Bayesian optimization and gradient descent were investigated for performing the classical optimization. Ansatz states for plaquette chains are constructed in a scalable manner from smaller systems using domain decomposition and a stitching procedure analogous to the density matrix renormalization group. Small examples are performed on IBM’s superconducting Manila processor.

The dynamical similarity which exists between the $\lambda$-mode excited $bbq$ baryons ($q$ refers to the $u$, $d$, and $s$ quarks) and the $\overline{b}q$ mesons inspires us to carry out a combined study of their spectroscopy. In this work, the masses and strong decays of these low-lying $b\overline{q}$ and $bbq$ states are studied by the same theoretical methods, and the dynamical similarity which is implied in their mass spectra and strong decays are also discussed. The recent discovered $\overline{b}q$ states, including the $B_J(5840)$, $B_J(5970)$, $B_{sJ}(6064)$, and $B_{sJ}(6114)$, are analyzed. According to our result, the $B_J(5840)$ could be assigned as a $2S$ state, while the $B_J(5970)$ could be regarded as a member of the $1D(2^{-},3^{-}{)}_{j_q=5/2}$ doublet. The $B_{sJ}(6064)$ and $B_{sJ}(6114)$ are probably the $D$-wave states. Especially, they could be explained as the members of the $1D(1^{-},2^{-}{)}_{j_q=3/2}$ and $1D(2^{-},3^{-}{)}_{j_q=5/2}$ doublets, respectively. The predicted masses and decay properties of other unknown $\overline{b}q/bbq$ states may provide useful clues to the future experiment.

We present an evaluation of the ${\pi }^{\pm }$ and $K^{\pm }$ box contributions to the hadronic light-by-light piece of the muon’s anomalous magnetic moment, $a_{\mu }$. The calculation of the corresponding electromagnetic form factors (EFFs) is performed within a Dyson-Schwinger equations (DSE) approach to quantum chromodynamics. These form factors are calculated in the so-called rainbow-ladder (RL) truncation, following two different evaluation methods and, subsequently, in a further improved approximation scheme which incorporates meson cloud effects. The results are mutually consistent, indicating that in the domain of relevance for $a_{\mu }$ the obtained EFFs are practically equivalent. Our analysis yields the combined estimates of $a_{\mu }^{{\pi }^{\pm }-\mathrm{box}}=-(15.6\pm 0.2)\times {10}^{-11}$ and $a_{\mu }^{K^{\pm }-\mathrm{box}}=-(0.48\pm 0.02)\times {10}^{-11}$, in full agreement with results previously obtained within the DSE formalism and other contemporary estimates.

We propose a new experimental technique to generate and detect axions in the lab with a good experimental sensitivity over a broad axion mass range. The scheme relies on using laser-based four-wave mixing, which is mediated by the hypothetical axion field. Intense pump and Stokes laser beams that are confined to a waveguide (i.e., for example, an optical fiber) with appropriately chosen frequencies resonantly drive axion generation. Under such a geometry, we predict the existence of guided axion waves, which we refer to as “axitons.” These are solutions of the axion Klein-Gordon field equation that are spatially guided by the profiles of the driving pump and Stokes laser beams. These guided axitons can then couple to a nearby fiber and mix with another laser, affecting the propagation of a probe laser beam. A key advantage of the scheme is that the mass range of the hypothetical axion can be scanned by varying the frequencies of the pump and the Stokes laser beams. We predict that, using reasonable parameters, the technique will be able to detect axions in the mass range ${10}^{-6}\mathrm{eV}<m<{10}^{-2}\mathrm{eV}$ with a sensitivity at the level of ${10}^{-12}{\mathrm{GeV}}^{-1}$ for the axion-photon coupling constant.

We present the results of the light sterile neutrino search from the second Karlsruhe Tritium Neutrino (KATRIN) measurement campaign in 2019. Approaching nominal activity, $3.76\times {10}^6$ tritium $\beta$-electrons are analyzed in an energy window extending down to 40 eV below the tritium end point at $E_0=18.57\mathrm{keV}$. We consider the $3\nu +1$ framework with three active and one sterile neutrino flavors. The analysis is sensitive to a fourth mass eigenstate $m_4^2\lesssim 1600{\mathrm{eV}}^2$ and active-to-sterile mixing $|U_{e4}{|}^2\gtrsim 6\times {10}^{-3}$. As no sterile-neutrino signal was observed, we provide improved exclusion contours on $m_4^2$ and $|U_{e4}{|}^2$ at 95% C.L. Our results supersede the limits from the Mainz and Troitsk experiments. Furthermore, we are able to exclude the large $\mathrm{\Delta }{m}_{41}^2$ solutions of the reactor antineutrino and gallium anomalies to a great extent. The latter has recently been reaffirmed by the BEST Collaboration and could be explained by a sterile neutrino with large mixing. While the remaining solutions at small $\mathrm{\Delta }{m}_{41}^2$ are mostly excluded by short-baseline reactor experiments, KATRIN is the only ongoing laboratory experiment to be sensitive to relevant solutions at large $\mathrm{\Delta }{m}_{41}^2$ through a robust spectral shape analysis.

We investigate the unflavored Schur indices of class-$\mathcal{S}$ theories of modest rank, and in the case of $\mathcal{N}=4$ super-Yang-Mills theory with a special unitary gauge group of somewhat more general rank, with an eye towards their modular properties. We find closed-form expressions for many of these theories in terms of quasimodular forms of level 1 or 2, with the curious feature that in general they are sums of quasimodular forms of different weights. For type-${\mathfrak{a}}_1$ theories, the index can be fixed by taking a simple Ansatz for the family of quasimodular forms appearing in the expansion of this type and demanding that the result be sufficiently regular as $q\to 0$. For higher-rank cases, an equally simple construction is lacking, but we nevertheless find that these indices can be expressed in terms of mixed-weight quasimodular forms.

Elliptic partial differential equations must be solved numerically for many problems in numerical relativity, such as initial data for every simulation of merging black holes and neutron stars. Existing elliptic solvers can take multiple days to solve these problems at high resolution and when matter is involved, because they are either hard to parallelize or require a large amount of computational resources. Here we present a new solver for linear and nonlinear elliptic problems that is designed to scale with resolution and to parallelize on computing clusters. To achieve this we employ a discontinuous Galerkin discretization, an iterative multigrid-Schwarz preconditioned Newton-Krylov algorithm, and a task-based parallelism paradigm. To accelerate convergence of the elliptic solver we have developed novel subdomain-preconditioning techniques. We find that our multigrid-Schwarz preconditioned elliptic solves achieve iteration counts that are independent of resolution, and our task-based parallel programs scale over 200 million degrees of freedom to at least a few thousand cores. Our new code solves a classic initial data problem for binary black holes faster than the spectral code SpEC when distributed to only eight cores, and in a fraction of the time on more cores. It is publicly accessible in the next-generation SpECTRE numerical relativity code. Our results pave the way for highly parallel elliptic solves in numerical relativity and beyond.

Our ability to characterize astrophysical gravitational waves depends on our understanding of the detectors used to observe them. Specifically, our ability to calibrate current kilometer-scale interferometers can potentially confound the inference of astrophysical signals. Current calibration uncertainties are dominated by systematic errors between the modeled and observed detector responses and are well described by a Gaussian process. I exploit this description to analytically examine the impact of calibration uncertainty. I derive closed-form expressions for the conditioned likelihood of the calibration error given the observed data and an astrophysical signal (astrophysical calibration) as well as for the marginal likelihood for the data given a signal (integrated over the calibration uncertainty). I show that calibration uncertainty always reduces search sensitivity and the amount of information available about astrophysical signals. Additionally, calibration uncertainty will fundamentally limit the precision to which loud signals can be constrained, a crucial factor when considering the scientific potential of proposed third-generation interferometers. For example, I estimate that with 1% uncertainty in the detector response’s amplitude and phase, one will only be able to measure the leading-order tidal parameter ($\tilde{\mathrm{\Lambda }}$) for a $1.4+1.4M_{\odot }$ system to better than $\pm 1$ ($\sim 0.2\%$ relative uncertainty) for signals with signal-to-noise ratios $\gtrsim {10}^4$. At this signal-to-noise ratio, calibration uncertainty increases ${\sigma }_{\tilde{\mathrm{\Lambda }}}$ by a factor of 2 compared to stationary Gaussian noise alone. Furthermore, 1% calibration uncertainty limits the precision to always be ${\sigma }_{\tilde{\mathrm{\Lambda }}}\gtrsim 0.5$. At more modest signal-to-noise ratios ($\lesssim 30$) characteristic of the current set of detected events, the uncertainty in $\tilde{\mathrm{\Lambda }}$ will be ${\sigma }_{\tilde{\mathrm{\Lambda }}}\gtrsim 100$ and will be dominated by the Gaussian noise rather than calibration uncertainty. I also show how to best select the frequencies at which calibration should be precisely constrained in order to minimize the information lost about astrophysical parameters. It is not necessary to constrain the calibration errors to be small at all frequencies to perform precise astrophysical inference for individual signals.

In this paper we introduce a self-consistent mean field approximation to study the QCD phase transition and the structure of hybrid stars within the framework of an NJL-type model. In our practice, a phenomenological parameter $\alpha$ is introduced, which reflects the weights of the “direct” channel and “exchange” channel under a finite chemical potential. The mass-radius relation is obtained by solving the Tolman-Oppenheimer-Volkoff equation using a crossover equation of state (EOS). We calculate the density distribution in a two solar-mass hybrid star to show the effects of different parameters. We also calculate the tidal Love number $k_2$ and the deformability ($\mathrm{\Lambda }$). It is found that the stiffness of the EOS increases with $\alpha$, which allows us to obtain a hybrid star with a maximum mass of 2.40 solar mass through our model. The observation of over 2.06 solar-mass neutron stars may indicate that the chiral transition may be a crossover on the whole $T\text{−}\mu$ plane.

The construction of large-scale liquid scintillator detectors is complicated by the need to separate the scintillation region from photomultiplier tubes due to their intrinsic radioactivity. This is generally done using acrylic or nylon barriers, whose own activity can also lead to a substantial reduction of the fiducial detection volume for a number of low energy ($\sim \mathrm{MeV}$) studies, and whose construction becomes increasingly difficult and expensive for larger detector volumes. Here we present an initial simulation study of an alternative geometric construction known as stratified liquid plane scintillator, which aims to avoid such physical barriers entirely by instead using layers of lipophobic liquids to separate photomultiplier tubes from the scintillation region.

Using a sample of $(10.09\pm 0.04)\times {10}^9$ $J/\psi$ events collected with the BESIII detector, a partial wave analysis of $J/\psi \to \gamma {\eta }^{\prime }{\eta }^{\prime }$ is performed. The masses and widths of the observed resonances and their branching fractions are reported. The main contribution is from $J/\psi \to \gamma f_0(2020)$ with $f_0(2020)\to {\eta }^{\prime }{\eta }^{\prime }$, which is found with a significance of greater than $25\sigma$. The product branching fraction $\mathcal{B}(J/\psi \to \gamma f_0(2020))·\mathcal{B}(f_0(2020)\to {\eta }^{\prime }{\eta }^{\prime })$ is measured to be $(2.63\pm 0.06(\mathrm{stat}.{)}_{-0.46}^{+0.31}(\mathrm{syst}.))\times {10}^{-4}$.

In electronic systems with flat bands, such as twisted bilayer graphene, interaction effects govern the structure of the phase diagram. In this paper, we show that a strongly interacting system featuring fermionic flat bands can be engineered using the holographic duality. In particular, we find that in the holographic nematic phase, two bulk Dirac cones separated in momentum space at low temperature, approach each other as the temperature increases. They eventually collide at a critical temperature yielding a flattened band with a quadratic dispersion. On the other hand, in the symmetric (Lifshitz) phase, this quadratic dispersion relation holds for any finite temperature. We therefore obtain a first holographic, strong-coupling realization of a topological phase transition where two Berry monopoles of charge one merge into a single one with charge two, which may be relevant for two- and three-dimensional topological semimetals.

We present the results of a conformal bootstrap study of the presumed unitary IR fixed point of quantum electrodynamics in three dimensions (${\mathrm{QED}}_3$) coupled to $N_f=4$ two-component Dirac fermions. Specifically, we study the four-point correlators of the $SU(4)$ adjoint fermion bilinear $r$ and the monopole of lowest topological charge ${\mathcal{M}}_{1/2}$. Most notably, the scaling dimensions of the fermion bilinear $r$ and the monopole ${\mathcal{M}}_{1/2}$ are found to be constrained into a closed island with a combination of spectrum assumptions inspired by the $1/N_f$ perturbative results as well as a novel interval positivity constraint on the next-lowest-charge monopole ${\mathcal{M}}_1$. Bounds in this island on the $SU(4)$ and topological $U(1{)}_t$ conserved current central charges $c_J$, $c_J^t$, as well as on the stress tensor central charge $c_T$, are comfortably consistent with the perturbative results. Together with the scaling dimensions, this suggests that a part of estimates from the $1/N_f$ expansion—even at $N_f=4$—provide a self-consistent solution to the bootstrap crossing equations, despite some of our assumptions not being strictly justified.

We solve the nonlocal equation $-e^{-{\ell }^2\square }\square \varphi =J$ for (i) static scalar fields in static spacetimes and (ii) time-dependent scalar fields in ultrastatic spacetimes. Corresponding equations are rewritten as nonlocal Poisson/inhomogeneous Helmholtz equations in compact and noncompact weighted/Riemannian manifolds using static/frequency-domain Green’s functions, which can be computed from the heat kernels in the respective manifolds. With the help of the heat kernel estimates, we derive the static Green’s function estimates and use them to discuss the regularity. We also present several examples of exact and estimated static/frequency-domain Green’s functions.

In this work we derive simple closed-form expressions for the dynamical friction acting on black holes moving through ultralight (scalar field) dark matter, covering both nonrelativistic and relativistic black hole speeds. Our derivation is based on long known scattering amplitudes in black hole spacetimes, it includes the effect of black hole spin and can be easily extended to vector and tensor light fields. Our results cover and complement recent numerical and previous nonrelativistic treatments of dynamical friction in ultralight dark matter.

Minute-long gravitational wave (GW) transients are events lasting from a few to hundreds of seconds. In opposition to compact binary mergers, their GW signals cover a wide range of poorly understood astrophysical phenomena such as accretion disk instabilities and magnetar flares. The lack of accurate and rapidly generated gravitational-wave emission models prevents the use of matched filtering methods. Such events are thus probed through the template-free excess-power method, consisting in searching for a local excess of power in the time-frequency space correlated between detectors. The problem can be viewed as a search for high-value clustered pixels within an image, which has been generally tackled by deep learning algorithms such as convolutional neural networks (CNNs). In this work, we use a CNN as a anomaly detection tool for the long-duration searches. We show that it can reach a pixel-wise detection despite trained with minimal assumptions, while being able to retrieve both astrophysical signals and noise transients originating from instrumental coupling within the detectors. We also note that our neural network can extrapolate and connect partially disjoint signal tracks in the time-frequency plane.

In this article we revisit the discussion of renormalons in the frame of a scalar self-interacting $\lambda {\varphi }^4$ theory in the presence of thermomagnetic effects, i.e., magnetic and thermal effects. Our results for the evolution of the residues is now given by an explicit analytic expression, valid for all values of temperature, without the necessity of separating the discussion in a low- and a high temperature region analyses. We carry out the same discussion for the case of an external constant electric field, obtaining also in this case an analytic expression for the whole range o temperature. In both cases, the location of the poles in the Borel plane does not change with respect to the vacuum case. Their residues, however, acquire a dependence on temperature and the external field. Results are presented for the evolution of residues in the thermomagnetic and thermoelectric cases. We show a comparison with our previous results in the thermomagnetic case, presenting also in detail the mathematical techniques needed for our analytic expressions to be valid in the whole range of temperatures.