Strong gravitational lensing is a promising way of uncovering the nature of dark matter, by finding perturbations to images that cannot be accounted for well by modeling the lens galaxy without additional structure, be it subhalos (smaller halos within the smooth lens) or line-of-sight (LOS) halos. We present results attempting to infer the presence of substructure from images without requiring an intermediate step in which a smooth model has to be subtracted, using a simple convolutional neural network (CNN). We find that the network is only able to infer the presence of subhalos with greater than 75% accuracy when they have masses of greater than or equal to $5\times {10}^9{M}_{\odot }$ if they lie within the main lens galaxy. Since less massive foreground LOS halos can have the same effect as higher-mass subhalos, the CNN can probe lower masses in the halo mass function. The accuracy does not improve significantly if we add a population of less massive subhalos. With the expectation of experiments such as Hubble Space Telescope and Euclid yielding thousands of high-quality strong lensing images in the next years, having a way of analyzing images quickly to identify candidates that merit further analysis to determine individual subhalo properties while preventing extensive resources being used for images that would yield null detections could be very useful. By understanding the sensitivity as a function of substructure mass, nondetections could be combined with the information from images with substructure to constrain the cold dark matter scenario, in particular if the sensitivity can be pushed to lower masses.

We show that standard puzzles of hot big bang cosmology that motivated the introduction of cosmological inflation, such as the smoothness and horizon problem, the flatness problem, and the relic problem are also solved by holographic models for very early universe based on perturbative three dimensional QFT. In the holographic setup, cosmic evolution is mapped to inverse renormalization group (RG) flow of the dual QFT, and the resolution of the puzzles relies on properties of the RG flow.

In this article we calculate the next-to-leading order (NLO) QCD corrections for single on-shell top-quark production in association with two jets at proton-proton colliders. The $tW$ channel is assumed to be measured independently. The QCD corrections to the inclusive cross section are about 28% (22%) for top (antitop) quark production at the 13 TeV LHC. Theoretical errors are dominated by scale uncertainties, which are found to be around 5% at NLO. Results for various kinematical distributions are also provided using a well-motivated dynamical scale. The QCD corrections are found to have a nontrivial dependence on the phase space.

Nonstandard neutrino interactions (NSI) are vector contact interactions involving two neutrinos and two first generation fermions, which can affect neutrino propagation in matter. SU(2) gauge invariance suggests that NSI should be accompanied by more observable charged lepton contact interactions. However, these can be avoided at tree level in various ways. We focus on lepton flavour-changing NSI, suppose they are generated by new physics heavier than $m_W$ that does not induce (charged) lepton flavor violation (LFV) at tree level, and show that LFV is generated at one loop in most cases. The current constraints on charged lepton flavor violation therefore suggest that $\mu \leftrightarrow e$ flavor-changing NSI are unobservable and $\tau \leftrightarrow \ell$ flavor-changing NSI are an order of magnitude weaker than the weak interactions. This conclusion can be avoided if the heavy new physics conspires to cancel the one-loop LFV, or if NSI are generated by light new physics to which our analysis does not apply.

We discuss $G$-parity lattice boundary conditions as a means to impose momentum on the pion ground state without breaking isospin symmetry. This technique is expected to be critical for the precision measurement of $K\to (\pi \pi {)}_{I=0}$ matrix elements where physical kinematics demands moving pions in the final state and the statistical noise caused by disconnected contributions will make it difficult to use multiexponential fits to isolate this as an excited state. We present a formalism for computing hadronic Green’s functions with $G$-parity boundary conditions, derive the discretized action and its symmetries, discuss how the strange quark can be introduced and detail techniques for the numerical implementation of these boundary conditions. We demonstrate and test these methods using several $16^3\times 32$ dynamical domain wall ensembles with a 420 MeV pion mass and $G$-parity boundary conditions in one and two spatial directions.

We present estimates of the hyperon elastic form factors for the baryon octet and the ${\mathrm{\Omega }}^{-}$ baryon for large four-momentum transfer squared $q^2$ in the timelike region ($q^2>0$). Experimentally, those form factors can be extracted from the $e^{+}{e}^{-}\to B\overline{B}$ and $p\overline{p}\to B\overline{B}$ processes, where $B$ stands for a general baryon. Our results are based on calculations of the elastic electromagnetic form factors in the spacelike region ($Q^2=-q^2>0$) within a covariant quark model. To connect the results in the spacelike region to those in the timelike region, we use asymptotic relations between the two regions which are constraints derived from analyticity and unitarity. We calculate the effective form factors $|G(q^2)|$ and compare them with the integrated cross section data ${\sigma }_{\text{Born}}(q^2)$ from BABAR, BES III, and CLEO. The available data are at the moment restricted to $\mathrm{\Lambda }$, ${\mathrm{\Sigma }}^0$, ${\mathrm{\Sigma }}^{-}$, ${\mathrm{\Xi }}^{-}$, ${\mathrm{\Xi }}^0$, and ${\mathrm{\Omega }}^{-}$ as well as to $e^{+}{e}^{-}\to \mathrm{\Lambda }{\overline{\mathrm{\Sigma }}}^0$ and $e^{+}{e}^{-}\to {\mathrm{\Sigma }}^0\overline{\mathrm{\Lambda }}$ reactions. Our results provide useful reference for future experiments and seem to indicate that the present data are still in the nonperturbative QCD region, while the onset for the asymptotic constraints from analyticity and unitarity happens much before the region of the perturbative QCD falloff of the form factors.

We study the dynamics of non-Abelian vortex strings supported in $\mathcal{N}=2$ supersymmetric QCD with the $\mathrm{U}(N)$ gauge group and $N_f=N$ quark flavors deformed by the mass $\mu$ of the adjoint matter. In the limit of large $\mu$ the bulk four-dimensional theory flows to $\mathcal{N}=1$ supersymmetric QCD. The dynamics of orientational zero modes of the non-Abelian string is described by the world sheet $CP(N-1)$ model. At $\mu =0$ this model has $\mathcal{N}=(2,2)$ supersymmetry while at large $\mu$ it flows to the nonsupersymmetric $CP(N-1)$ model. We solve the world sheet model in the large $N$ approximation and find a rich phase structure with respect to the deformation parameter $\mu$ and quark mass differences. The phases include two strong coupling phases and two Higgs phases. In particular, the Higgs phase at small $\mu$ supports $CP(N-1)$ model kinks representing confined monopoles of the bulk QCD, while in the large-$\mu$ Higgs phase monopoles disappear.

We obtain a relativistically covariant wave equation for neutrinos in dense matter and electromagnetic field, which describes both flavor oscillations and neutrino spin rotation. Using this equation we construct a quasiclassical theory of these phenomena. We obtain the probabilities of arbitrary spin-flavor transitions assuming the external conditions to be constant. We demonstrate that the resonance behavior of the transition probabilities is possible only when the neutrino flavor states cannot be described as superpositions of the mass eigenstates. We discover that a resonance, which is similar to the Mikheev–Smirnov–Wolfenstein resonance, takes place for neutrinos in magnetic field due to the transition magnetic moments. This resonance gives an opportunity to determine, whether neutrinos are Dirac or Majorana particles.

The cross section of the process $e^{+}{e}^{-}\to {\eta }^{\prime }J/\psi$ is measured at center-of-mass (c.m.) energies from $\sqrt{s}=4.178$ to 4.600 GeV using data samples corresponding to a total integrated luminosity of $11{\mathrm{fb}}^{-1}$ collected with the BESIII detector operating at the BEPCII storage ring. The dependence of the cross section on $\sqrt{s}$ shows an enhancement around 4.2 GeV. While the shape of the cross section cannot be fully explained with a single $\psi (4160)$ or $\psi (4260)$ state, a coherent sum of the two states does provide a reasonable description of the data.

We report the measurements of the single and double differential cross section of muon neutrino charged-current interactions on carbon with a single positively charged pion in the final state at the T2K off-axis near detector using $5.56\times {10}^{20}$ protons on target. The analysis uses data control samples for the background subtraction and the cross section signal, defined as a single negatively charged muon and a single positively charged pion exiting from the target nucleus, is extracted using an unfolding method. The model-dependent cross section, integrated over the T2K off-axis neutrino beam spectrum peaking at 0.6 GeV, is measured to be $\sigma =(11.76\pm 0.44(\mathrm{stat})\pm 2.39(\mathrm{syst}))\times {10}^{-40}{\mathrm{cm}}^2{\text{nucleon}}^{-1}$. Various differential cross sections are measured, including the first measurement of the Adler angles for single charged pion production in neutrino interactions with heavy nuclei target.

Inspirals of stellar-mass compact objects into supermassive black holes are known as extreme mass ratio inspirals. In the simplest approximation, the motion of the compact object is modeled as a geodesic in the space-time of the massive black hole with the orbit decaying due to radiated energy and angular momentum, thus yielding a highly regular inspiral. However, once the spin of the secondary compact body is taken into account, integrability is broken and prolonged resonances along with chaotic motion appear. We numerically integrate the motion of a spinning test body in the field of a nonspinning black hole and analyze it using various methods. We show for the first time that resonances and chaos can be found even for astrophysically relevant values of the spin of the test body. On the other hand, we devise a method to analyze the growth of the resonances, and we conclude that the prolonged resonances we observe are only caused by terms quadratic in spin and will generally stay very small in the small-mass-ratio limit. Last but not least, we compute gravitational waveforms by numerically solving the Teukolsky equations in the time-domain and establish that they carry information on the motion’s dynamics. In particular, we show that the time series of the gravitational wave strain can be used to discern regular from chaotic motion of the source.

We apply the DDC formalism [proposed by Dalibard, Dupont-Roc and Cohen-Tannoudji] to study the average rate of change of energy of two identical two-level atoms interacting with the vacuum massless scalar field in synchronized motion along stationary trajectories. By separating the contributions of vacuum fluctuations and atomic radiation reaction, we first show that for the two-atom system initially prepared in the factorizable eigenstates $|g_A{g}_B⟩$ and $|e_A{e}_B⟩$, where $g$ and $e$ represent the ground state and the excited state of a single atom, respectively, both vacuum fluctuations and atomic radiation reaction contribute to the average rate of change of energy of the two-atom system, and the contribution of vacuum fluctuations is independent of the interatomic separation while that of atomic radiation reaction is dependent on it. This is contrary to the existing results in the literature where vacuum fluctuations are interatomic-separation dependent. However, if the two-atom system is initially prepared in the unfactorizable symmetric/antisymmetric entangled state, the average rate of change of energy of the two-atom system is never perturbed by the vacuum fluctuations, but is totally a result of the atomic radiation reaction. We then consider two special cases of motion of the two-atom system, which is initially prepared in the symmetric/antisymmetric entangled state, i.e., synchronized inertial motion and synchronized uniform acceleration. In contrast to the average rate of change of energy of a single uniformly accelerated atom, the average rate of change of energy of the uniformly accelerated two-atom system is nonthermal-like. The effects of noninertial motion on the transitions of states of the two correlated atoms are also discussed.

We derive all hairy stealth black holes in the most general second-order, shift symmetric, scalar-tensor theory with luminally propagating gravitational waves, often called kinetic gravity braiding. Our approach exploits a loophole in a recently obtained no-go statement which claims shift symmetry breaking to be necessary for stealth solutions to exist in kinetic gravity braiding. We highlight the essential role played by a covariantly constant kinetic density in obtaining these solutions. Lastly, we propose a parametrization of the theories based on the asymptotics of its stealth solutions and comment on the intriguing singular effective metric for scalar perturbations in stealth black holes.

Motivated by the recent work of Chigusa, Moroi, and Shoji, we propose a new simple gradient flow equation to derive the bounce solution which contributes to the decay of the false vacuum. Our discussion utilizes the discussion of Coleman, Glaser, and Martin, and we solve a minimization problem of the kinetic energy while fixing the potential energy. The bounce solution is derived as a scale transformation of the solution of this problem. We also show that the convergence of our method is robust against a choice of the initial configuration.

We present a calculation of the transverse momentum broadening of a high-energy fundamental-representation particle, as calculated nonperturbatively within EQCD using the technique proposed by Caron-Huot and pioneered by Panero, Schäfer, and Rummukainen. Our results are continuum extrapolated and provided at four temperatures: 250 MeV, 500 MeV, 1 GeV, and 100 GeV.

In this paper we study generic features of nonlocal charges obtained from marginal deformations of Wess-Zumino-Novikov-Witten models. Using free-field representations of CFTs based on simply laced Lie algebras, one can use simple arguments to build the nonlocal charges; but for more general Lie algebras these methods are not strong enough to be generally used. We propose a brute force calculation where the nonlocality is associated to a new Lie algebra valued field, and from this prescription we impose several constraints on the algebra of nonlocal charges. Possible applications for Yang-Baxter and holographic $T\overline{T}$ and $T\overline{J}$ deformations are also discussed.

Using the time evolution equations of (cosmological) general relativity in the first order Fischer-Marsden form, we construct an integral that measures the amount of nonstationary energy on a given spacelike hypersurface in $D$ dimensions. The integral vanishes for stationary spacetimes; and with a further assumption, reduces to Dain’s invariant on the boundary of the hypersurface which is defined with the Einstein constraints and a fourth order equation defining approximate Killing symmetries.

We develop a parameter-free velocity-dependent one-scale model for the evolution of the characteristic length $L$ and root-mean-square velocity ${\sigma }_v$ of standard domain wall networks in homogeneous and isotropic cosmologies. We compare the frictionless scaling solutions predicted by our model, in the context of cosmological models having a power law evolution of the scale factor $a$ as a function of the cosmic time $t$ ($a\propto t^{\lambda }$, $0<\lambda <1$), with the corresponding results obtained using field theory numerical simulations. We show that they agree well (within a few %) for root-mean-square velocities ${\sigma }_v$ smaller than $0.2c$ ($\lambda \ge 0.9$), where $c$ is the speed of light in vacuum, but significant discrepancies occur for larger values of ${\sigma }_v$ (smaller values of $\lambda$). We identify problems with the determination of $L$ and ${\sigma }_v$ from numerical field theory simulations which might potentially be responsible for these discrepancies.