We study the stability of pentaquarks within a schematic model based on SU(3) color symmetry, by taking into account algebraic arguments leading to a chromoelectric interaction containing two- and three-body parts. It has already been proven that such an interaction can influence the spectrum of ordinary baryons and the stability of tetraquarks and hexaquarks. Here, we discuss its role in the stability of pentaquarks against strong decays.

We reexamine, update and extend a suggestion we made fifteen years ago for measuring the photon polarization in $b\to s\gamma$ by observing in $B\to K\pi \pi \gamma$ an asymmetry of the photon with respect to the $K\pi \pi$ plane. Asymmetries are calculated for different charged final states due to intermediate $K_1(1400)$ and $K_1(1270)$ resonant states. Three distinct interference mechanisms are identified contributing to asymmetries at different levels for these two kaon resonances. For $K_1(1400)$ decays including a final state ${\pi }^0$ an asymmetry around $+30\%$ is calculated, dominated by interference of two intermediate $K^{*}\pi$ states, while an asymmetry around $+10\%$ in decays including final ${\pi }^{+}{\pi }^{-}$ is dominated by interference of $S$ and $D$ wave $K^{*}\pi$ amplitudes. In decays via $K_1(1270)$ to final states including a ${\pi }^0$ a negative asymmetry is favored up to $-10\%$ if one assumes $S$ wave dominance in decays to $K^{*}\pi$ and $K\rho$, while in decays involving ${\pi }^{+}{\pi }^{-}$ the asymmetry can vary anywhere in the range $-13\%$ to $+24\%$ depending on unknown phases. For more precise asymmetry predictions in the latter decays we propose studying phases in $K_1\to K^{*}\pi ,K\rho$ by performing dedicated amplitude analyses of $B\to J/\psi ({\psi }^{\prime })K\pi \pi$. In order to increase statistics in studies of $B\to K\pi \pi \gamma$ we suggest using isospin symmetry to combine in the same analysis samples of charged and neutral $B$ decays.

The deformation operator of the D1-D5 orbifold CFT, a twist-2 operator, drives the CFT towards the black hole dual, and its physics is key to understanding thermalization in the D1-D5 system. To further study this deformation, we extend previous work on the effect of twist-2 operators to a method that works for higher orders, in the continuum limit. Our component twist method works by building higher-twist operators out of twist-2 operators, together with knowledge of Bogoliubov transformations. Consequently, this method sidesteps limitations in Lunin-Mathur technology by avoiding lifts to the covering space. We verify the method by reproducing results obtainable with Lunin-Mathur technology. Going further, our method upholds a previously conjectured scaling law in the continuum limit that applies to any generic configuration of twists. We illustrate this with computations for a new configuration of two twist-2 operators that twists three copies together.

Asymptotically free renormalization group trajectories can be constructed in non-Abelian Higgs models with the aid of generalized boundary conditions imposed on the renormalized action. We detail this construction within the languages of simple low-order perturbation theory, effective field theory, as well as modern functional renormalization group equations. We construct a family of explicit scaling solutions using a controlled weak-coupling expansion in the ultraviolet, and obtain a standard Wilsonian renormalization group relevance classification of perturbations about scaling solutions. We obtain global information about the quasifixed function for the scalar potential by means of analytic asymptotic expansions and numerical shooting methods. Further analytical evidence for such asymptotically free theories is provided in the large-$N$ limit. We estimate the long-range properties of these theories and identify initial/boundary conditions giving rise to a conventional Higgs phase.

We revisit the problem of the bulk-boundary unitarity clash in $2+1$–dimensional gravity theories, which has been an obstacle in providing a viable dual two-dimensional conformal field theory for bulk gravity in anti–de Sitter (AdS) spacetime. Chiral gravity, which is a particular limit of cosmological topologically massive gravity (TMG), suffers from perturbative log-modes with negative energies inducing a nonunitary logarithmic boundary field theory. We show here that any $f(R)$ extension of TMG does not improve the situation. We also study the perturbative modes in the metric formulation of minimal massive gravity—originally constructed in a first-order formulation—and find that the massive mode has again negative energy except in the chiral limit. We comment on this issue and also discuss a possible solution to the problem of negative-energy modes. In any of these theories, the infinitesimal dangerous deformations might not be integrable to full solutions; this suggests a linearization instability of AdS spacetime in the direction of the perturbative log-modes.

In Mod. Phys. Lett. A 31, 1650213 (2016), Nojiri proposed a simple model in order to solve one of the problems related to the cosmological constant. The model is induced from a topological field theory, and the model has an infinite number of BRS symmetries. The BRS symmetries are, in general, spontaneously broken, however. We investigate the BRS symmetry in detail and show that there is one and only one BRS symmetry which is not broken, and the unitarity can be guaranteed. In the model, the quantum problem of the vacuum energy, which may be identified with the cosmological constant, reduces to the classical problem of the initial condition. We investigate the cosmology given by the model and specify the region of the initial conditions, which could be consistent with the evolution of the Universe. We also show that there is a stable solution describing the de Sitter space-time, which may explain the accelerating expansion in the current Universe.

We consider the propagation of electromagnetic (EM) waves in the gravitational field of the Sun within the first post-Newtonian approximation of the general theory of relativity. We solve Maxwell’s equations for the EM field propagating on the background of a static mass monopole and find an exact closed form solution for the Debye potentials, which, in turn, yield a solution to the problem of diffraction of EM waves in the gravitational field of the Sun. The solution is given in terms of the confluent hypergeometric function and, as such, it is valid for all distances and angles. Using this solution, we develop a wave-theoretical description of the solar gravitational lens (SGL) and derive expressions for the EM field and energy flux in the immediate vicinity of the focal line of the SGL. Aiming at the potential practical applications of the SGL, we study its optical properties and discuss its suitability for direct high-resolution imaging of a distant exoplanet.

In the post-Newtonian (PN) regime, the time scale on which the spins of binary black holes precess is much shorter than the radiation-reaction time scale on which the black holes inspiral to smaller separations. On the precession time scale, the angle between the total and orbital angular momenta oscillates with nutation period $\tau$, during which the orbital angular momentum precesses about the total angular momentum by an angle $\alpha$. This defines two distinct frequencies that vary on the radiation-reaction time scale: the nutation frequency $\omega \equiv 2\pi /\tau$ and the precession frequency $\mathrm{\Omega }\equiv \alpha /\tau$. We use analytic solutions for generic spin precession at 2PN order to derive Fourier series for the total and orbital angular momenta in which each term is a sinusoid with frequency $\mathrm{\Omega }-n\omega$ for integer $n$. As black holes inspiral, they can pass through nutational resonances ($\mathrm{\Omega }=n\omega$) at which the total angular momentum tilts. We derive an approximate expression for this tilt angle and show that it is usually less than ${10}^{-3}$ radians for nutational resonances at binary separations $r>10M$. The large tilts occurring during transitional precession (near zero total angular momentum) are a consequence of such states being approximate $n=0$ nutational resonances. Our new Fourier series for the total and orbital angular momenta converge rapidly with $n$ providing an intuitive and computationally efficient approach to understanding generic precession that may facilitate future calculations of gravitational waveforms in the PN regime.

Supersolid inflation is a class of inflationary theories that simultaneously breaks time and space reparametrization invariance during inflation, with distinctive features for the dynamics of cosmological fluctuations. We investigate concrete realizations of such a scenario, including non-minimal couplings between gravity and the fields driving inflation. We focus in particular on the dynamics of primordial gravitational waves and discuss how their properties depend on the pattern of symmetry breaking that we consider. Tensor modes can have a blue spectrum, and for the first time we build models in which the squeezed limit of primordial tensor bispectra can be parametrically enhanced with respect to standard single-field scenarios. At leading order in a perturbative expansion, the tensor-to-scalar ratio depends only on the parameter controlling the breaking of space reparametrization. It is independent from the quantities controlling the breaking of time reparametrization, and this represents a difference with respect to standard single-field inflationary models.

Linear perturbations of the wave dark matter, or $\psi$ dark matter ($\psi \mathrm{DM}$), of particle mass $\sim {10}^{-22}\mathrm{eV}$ in the radiation-dominant era are analyzed, and the matter power spectrum at the photon-matter equality is obtained. We identify four phases of evolution for $\psi \mathrm{DM}$ perturbations, where the dynamics can be vastly different from the counterparts of cold dark matter (CDM). While in late stages, after mass oscillation, long-wave $\psi \mathrm{DM}$ perturbations are almost identical to CDM perturbations, some subtle differences remain. The differences are even greater with intermediate-to-short waves that bear no resemblance to those of CDM throughout the whole evolutionary history. The dissimilarity is due to quantum mechanical effects which lead to severe mode suppression. We also discuss the axion model with a cosine field potential. The power spectrum of axion models is generally almost identical to that of $\psi \mathrm{DM}$, but in the extreme case, when the initial axion angle is near the field potential top, this axion model predicts a power excess over a range of wave numbers and a higher spectral cutoff than $\psi \mathrm{DM}$, as if $\psi \mathrm{DM}$ had a higher particle mass.

We study dark matter production in scenarios where a scale invariant hidden sector interacts with the Standard Model degrees of freedom via a Higgs portal $\lambda {\mathrm{\Phi }}^{†}\mathrm{\Phi }{s}^2$. If the hidden sector is very weakly coupled to the SM but exhibits strong interactions within its own particle species, the dark matter abundance may arise as a result of a dark freeze-out occurring in the hidden sector. Because of scale invariance, the free parameters in the hidden sector are determined, and the dark matter candidate exhibits a “WIMP miracle of the second kind.” Demonstrating the predictive power of scale invariance, we carry out a thorough analysis of dark matter production in several benchmark scenarios where the hidden sector contains either a scalar, fermion (sterile neutrino), or vector dark matter and discuss the observational consequences of these scenarios.

The response of elastic materials to external changing conditions can proceed through small and discrete releases of stress, rather than a continuous and smooth deformation as described by the classical elasticity theory. In a macroscopic elastic body, the sum of all those small crackling events can create a detectable displacement noise (crackling noise). In this paper we consider the case of the steel cantilevers used in the seismic isolation systems of ground based gravitational wave detectors, to provide the vertical isolation needed to reach the detector target sensitivity. Those instruments are reaching unprecedented displacement sensitivity, at a level that might be limited by crackling noise in the aforementioned cantilevers. Understanding this source of noise is extremely important, especially considering its intrinsic nonlinear nature. Since a detailed microscopical model of crackling noise in polycrystalline steel is not available at the moment, we suggest a phenomenological microscopical model, and the focus of this paper is on how crackling noise scales with the size and geometry of the cantilevers. The goal of this paper is to provide a method to scale up future measurements of crackling noise from small test cantilevers to the large ones used in advanced gravitational wave detectors.

During their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass $100M_{\odot }$, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than $0.93{\mathrm{Gpc}}^{-3}{\mathrm{yr}}^{-1}$ in comoving units at the 90% confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits.

We apply recent results on the probability distribution for quantum stress tensor fluctuations to the problem of barrier penetration by quantum particles. The probability for large stress tensor fluctuations decreases relatively slowly with increasing magnitude of the fluctuation, especially when the quantum stress tensor operator has been averaged over a finite time interval. This can lead to large vacuum radiation pressure fluctuations on charged or polarizable particles, which can in turn push the particle over a potential barrier. The rate for this effect depends sensitively upon the details of the time averaging of the stress tensor operator, which might be determined by factors such as the shape of the potential. We make some estimates for the rate of barrier penetration by this mechanism and argue that in some cases this rate can exceed the rate for quantum tunneling through the barrier. The possibility of observation of this effect is discussed.

We analyze the impact of QCD corrections on limits derived from neutrinoless double beta decay ($0\nu \beta \beta$). As demonstrated previously, the effect of the color mismatch arising from loops with gluons linking the quarks from different color-singlet currents participating in the effective operators has a dramatic impact on the predictions for some particular Wilson coefficients. Here, we consider all possible contributions from heavy particle exchange, i.e. the so-called short-range mechanism of $0\nu \beta \beta$ decay. All high-scale models (HSM) in this class match at some scale around a $\sim$ few TeV with the corresponding effective theory, containing a certain set of effective dimension-9 operators. Many of these HSM receive contributions from more than one of the basic operators and we calculate limits on these models using the latest experimental data. We also show with one nontrivial example, how to derive limits on more complicated models, in which many different Feynman diagrams contribute to $0\nu \beta \beta$ decay, using our general method.

Scalar tops in the supersymmetric model affect the potential of the standard model-like Higgs at the quantum level. In light of the equivalence theorem, the deviation of the potential from the standard model can be traced by longitudinal gauge bosons. In this work, high-energy longitudinal $W$ boson scattering is studied in a TeV-scale scalar top scenario. $\mathcal{O}(1–10\%)$ deviation from the standard model prediction in the differential cross section is found, depending on whether the observed Higgs mass is explained only by scalar tops or by additional contributions at a higher scale.

We revisit the calculation of the relic density of dark matter particles co-annihilating with a top or bottom partner by properly including the QCD bound-states (onia) effects of the colored partners as well as the relevant electroweak processes, which become important in the low-mass region. We carefully set up the complete framework that incorporates the relevant contributions and investigate their effects on the cosmologically preferred mass spectrum, which turn out to be comparable in size to those coming from the Sommerfeld enhancement. We apply the calculation to three scenarios: bino-stop and bino-sbottom co-annihilations in supersymmetry and a vector dark matter co-annihilating with a fermionic top partner. In addition, we confront our analysis of the relic abundance with recent direct detection experiments and collider searches at the LHC, which have important implications in the bino-stop and bino-sbottom scenarios. In particular, in the bino-stop case, recent LHC limits have excluded regions of parameter space with a direct detection rate that is above the neutrino floor.

We study the confinement-deconfinement transition in $SU(2)$ gauge theory in the presence of bosons with vanishing bare mass using lattice Monte Carlo simulations. The nature of this transition depends on the temporal extent ($N_{\tau }$) of the Euclidean lattice. We find that the transition is a crossover for $N_{\tau }=2$, 4 and second order with the three-dimensional Ising universality class for $N_{\tau }=8$. Our results show that the second-order transition is accompanied by the realization of the $Z_2$ symmetry.

Lattice quantum chromodynamics (QCD) provides the only known systematic, nonperturbative method for first-principles calculations of nucleon structure. However, for quantities such as light-front parton distribution functions (PDFs) and generalized parton distributions (GPDs), the restriction to Euclidean time prevents direct calculation of the desired observable. Recently, progress has been made in relating these quantities to matrix elements of spatially nonlocal, zero-time operators, referred to as quasidistributions. Still, even for these time-independent matrix elements, potential subtleties have been identified in the role of the Euclidean signature. In this work, we investigate the analytic behavior of spatially nonlocal correlation functions and demonstrate that the matrix elements obtained from Euclidean lattice QCD are identical to those obtained using the Lehmann-Symanzik-Zimmermann reduction formula in Minkowski space. After arguing the equivalence on general grounds, we also show that it holds in a perturbative calculation, where special care is needed to identify the lattice prediction. Finally we present a proof of the uniqueness of the matrix elements obtained from Minkowski and Euclidean correlation functions to all order in perturbation theory.

The pion superfluid and the corresponding Goldstone and soft modes are investigated in a two-flavor quark-meson model with a functional renormalization group. By solving the flow equations for the effective potential and the meson two-point functions at finite temperature and isospin density, the critical temperature for the superfluid increases sizeably in comparison with solving the flow equation for the potential only. The spectral function for the soft mode shows clearly a transition from meson gas to quark gas with increasing temperature and a crossover from Bose-Einstein condensation to Bardeen-Cooper-Schrieffer pairing of quarks with increasing isospin density.