The time-dependent $CP$ asymmetries in $B^0\to {\pi }^{+}{\pi }^{-}$ and $B_s^0\to K^{+}{K}^{-}$ decays are measured using a data sample of $p$ $p$ collisions corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The same data sample is used to measure the time-integrated $CP$ asymmetries in $B^0\to K^{+}{\pi }^{-}$ and $B_s^0\to {\pi }^{+}{K}^{-}$ decays. The results are $C_{{\pi }^{+}{\pi }^{-}}=-0.34\pm 0.06\pm 0.01$, $S_{{\pi }^{+}{\pi }^{-}}=-0.63\pm 0.05\pm 0.01$, $C_{K^{+}{K}^{-}}=0.20\pm 0.06\pm 0.02$, $S_{K^{+}{K}^{-}}=0.18\pm 0.06\pm 0.02$, $A_{K^{+}{K}^{-}}^{\mathrm{\Delta }\mathrm{\Gamma }}=-0.79\pm 0.07\pm 0.10$, $A_{CP}^{B^0}=-0.084\pm 0.004\pm 0.003$, and $A_{CP}^{B_s^0}=0.213\pm 0.015\pm 0.007$, where the first uncertainties are statistical and the second systematic. Evidence for $CP$ violation is found in the $B_s^0\to K^{+}{K}^{-}$ decay for the first time.

In this article, we establish the notion of classical Yangian symmetry for planar $\mathcal{N}=4$ supersymmetric Yang-Mills theory and for related planar gauge theories. After revisiting Yangian invariance for the equations of motion, we describe how the bilocal generators act on the action of the model such that the latter becomes exactly invariant. In particular, we elaborate on the relevance of the planar limit and how to act nonlinearly with bilocal generators on the cyclic action.

In this paper, admitting a de Sitter (dS)-invariant vacuum in an indefinite inner product space, we present a Gupta-Bleuler type setting for causal and full dS-covariant quantization of free “massless” spin-2 field in dS spacetime. The term “massless” stands for the fact that the field displays gauge and conformal invariance properties. In this construction, the field is defined rigorously as an operator-valued distribution. It is covariant in the usual strong sense: ${\underset{\_}{U}}_g\underset{\_}{\mathcal{K}}(X){\underset{\_}{U}}_g^{-1}=\underset{\_}{\mathcal{K}}(g.X)$, for any $g$ in the dS group, where $\underset{\_}{U}$ is associated with the indecomposable representations of the dS group, $S{O}_0(1,4)$, on the space of states. The theory, therefore, does not suffer from infrared divergences. Despite the appearance of negative norm states in the theory, the energy operator is positive in all physical states and vanishes in the vacuum.

Gravitational light bending by compact stars is an important astrophysical phenomenon. The bending angle depends on the stellar compactness, which is the ratio of stellar mass $M$ to radius $R$. In this paper, we investigate the pulse profile of highly compact rotating neutron stars for which the bending angle exceeds $\pi /2$. When $M/R>0.284$ (the bending angle becomes equal to $\pi /2$ for the stellar model with $M/R=0.284$), such a large bending happens, resulting in that a photon emitted from any position on the stellar surface can reach an observer. First, we classify the parameter plane of inclination angle $i$ and angle $\mathrm{\Theta }$ between the rotation axis and the normal on the hot spot by the number of photon paths reaching the observer. Then, we estimate the time-dependent flux of photons emitted from two hot spots on the rotating neutron star, associated with the magnetic polar caps, for various combinations of $i$ and $\mathrm{\Theta }$, and for two values of compactness, assuming that the stellar rotation is not so fast that the frame dragging and the stellar deformation are negligible. As the result, we find that the pulse profiles of highly compact neutron stars are qualitatively different from those for the standard neutron stars. In particular, the ratio of the maximum observed flux to the minimum one is significantly larger than that for the standard neutron stars. This study suggests that one would be able to constrain the equation of state for neutron stars through the observation of pulse profile with angles $i$ and $\mathrm{\Theta }$ determined by other methods.

In the mHz gravitational-wave band, galactic ultracompact binaries (UCBs) are continuous sources emitting at near-constant frequency. The signals from many of these galactic binaries will be sufficiently strong to be detectable by the Laser Interferometer Space Antenna (LISA) after $\sim \mathcal{O}(1\mathrm{week})$ of observing. In addition to their astrophysical value, these UCBs can be used to monitor the data quality of the observatory. This paper demonstrates the capabilities of galactic UCBs to be used as calibration sources for LISA by demanding signal coherence between adjacent week-long data segments separated by a gap in time of a priori unknown duration. A parameter for the gap duration is added to the UCB waveform model and used in a Markov-chain Monte Carlo algorithm simultaneously fitting for the astrophysical source parameters. Results from measurements of several UCBs are combined to produce a joint posterior on the gap duration. The measurement accuracy’s dependence on how much is known about the UCBs through prior observing, and seasonal variations due to the LISA orbital motion, is quantified. The duration of data gaps in a two-week segment of data can be constrained to within $\sim 0.2\mathrm{s}$ using $\mathcal{O}(10)$ UCBs after one month of observing. The timing accuracy from UCBs improves to $\lesssim 0.1\mathrm{s}$ after 1 year of mission operations. These results are robust to within a factor of $\sim 2$ when taking into account seasonal variations.

In [Gusakov et al. Phys. Rev. D 96, 103012 (2017)], we proposed a self-consistent method to study the quasistationary evolution of the magnetic field in neutron-star cores. Here, we apply it to calculate the instantaneous particle velocities and other parameters of interest, which are fixed by specifying the magnetic field configuration. Interestingly, we found that the magnetic field can lead to generation of a macroscopic fluid motion with the velocity significantly exceeding the diffusion particle velocities. This result calls into question the standard view on the magnetic field evolution in neutron stars and suggests a new, shorter time scale for such evolution.

The strange form factors of the nucleon are studied with the nonlocal chiral effective Lagrangian. One loop contributions from both octet and decuplet intermediate states are included. The relativistic regulator is obtained by the nonlocal Lagrangian where the gauge link is introduced to guarantee the local gauge symmetry. With the kaon loop, the calculated charge form factor is positive, while the magnetic form factor is negative. The strange magnetic moment is $-0.041_{-0.014}^{+0.012}$ with $\mathrm{\Lambda }=0.9\pm 0.1$ determined from the nucleon electromagnetic form factors. Our results are comparable with the recent lattice simulation.

For the minimal QCD axion model it is generally believed that overproduction of dark matter constrains the axion mass to be above a certain threshold, or at least that the initial misalignment angle must be tuned if the mass is below that threshold. We demonstrate that this is incorrect. During inflation the axion tends toward an equilibrium, assuming the Hubble scale is low and inflation lasts sufficiently long. This means the minimal QCD axion can naturally give the observed dark matter abundance in the entire lower part of the mass range, down to masses $\sim {10}^{-12}\mathrm{eV}$ (or $f_a$ up to almost the Planck scale). The axion abundance is generated by quantum fluctuations of the field during inflation. This mechanism generates cold dark matter with negligible isocurvature perturbations. In addition to the QCD axion, this mechanism can also generate a cosmological abundance of axionlike particles and other light fields.

Recent measurements of semileptonic B-meson decays seemingly imply violations of lepton flavor universality beyond the Standard Model predictions. With three-level explanations based on extended Higgs sectors being strongly challenged by the measurements of the $B_c^{-}$ lifetime, new theories invoking leptoquark or vector fields appear as the only feasible answer. However, in this work we show that simple scalar extensions of the Standard Model still offer a possible solution to the $B$ physics puzzle, owing to sizeable loop-level corrections which mimic the effects of new vector contributions. Considering a simplified model characterized by a charged and a neutral scalar particle, we verify the compatibility of the observed $R_{D^{(*)}}$ signal with the relevant collider bounds. We also study an embedding of the simplified model into a three-Higgs-doublet framework and investigate its main phenomenological constraints.

We construct a new gauged $U(1{)}_{\mathfrak{l}}$ lepton-number model that is anomaly-free for each standard model generation. The active neutrino masses are radiatively generated with a minimal scalar sector. The phenomenology and collider signals are studied. The interference effects among the new gauge boson, $Z_{\ell }$, photon, and $Z$ boson can be probed at the future $e^{+}{e}^{-}$ colliders even if the center-of-mass energy is below the mass of $Z_{\ell }$. Moreover, the electroweak precision sets a stringent bound on the mass splitting of the new lepton doublets.

In the light of recent experimental results from IceCube, LHC searches for scalar leptoquark, and the flavor anomalies $R_K$ and $R_{K^{*}}$, we analyze two scalar leptoquark models with hypercharge $Y=1/6$ and $Y=7/6$. We consider the 53 high-energy starting events from IceCube and perform a statistical analysis, taking into account both the Standard Model and leptoquark contribution together. The lighter leptoquark states that are in agreement with IceCube are strongly constrained from LHC di-lepton+dijet search. Heavier leptoquarks in the TeV mass range are in agreement both with IceCube and LHC. We furthermore show that leptoquark, which explains the $B$-physics anomalies and does not have any coupling with the third generation of quarks and leptons, can be strongly constrained.

We consider a minimal model where the Higgs boson arises as an elementary pseudo-Nambu-Goldstone boson. The model is based on an extended scalar sector with global $\mathrm{SO}(5)/\mathrm{SO}(4)$ symmetry. To achieve the correct electroweak symmetry-breaking pattern, the model is augmented either with an explicit symmetry-breaking term or an extra singlet scalar field. We consider separately both of these possibilities. We fit the model with the known particle spectrum at the electroweak scale and extrapolate to high energies using renormalization group. We find that the model can remain stable and perturbative up to the Planck scale provided that the heavy beyond standard model scalar states have masses in a narrow interval around 3 TeV.

Using complex Langevin dynamics we examine the phase structure of complex unitary matrix models and compare the numerical results with analytic results found at large $N$. The actions we consider are manifestly complex, and thus the dominant contribution to the path integral comes from the space of complexified gauge field configuration. For this reason, the eigenvalues of unitary matrix lie off the unit circle and venture out in the complex plane. One example of a complex unitary matrix model, with Polyakov line as the unitary matrix, is an effective description of a QCD at finite density and temperature with $N$ number of colors and $N_f$ number of quark flavors defined on the manifold $S^1\times S^3$. A distinct feature of this model, the occurrence of a series of Gross-Witten-Wadia transitions, as a function of the quark chemical potential, is reproduced using complex Langevin simulations. We simulate several other observables including Polyakov lines and quark number density, for large $N$ and $N_f$ and found excellent match with the analytic results.

The gravitational form factors for a hadron, the form factors for the hadron matrix element of the QCD energy-momentum tensor, not only describe the coupling of the hadron with a graviton, but also serve as unique quantities for describing the shape inside the hadron reflecting dynamics of quarks and gluons, such as the internal shear forces acting on the quarks/gluons and their pressure distributions. We consider the quark contribution to the gravitational form factors for a (pseudo)scalar hadron, and derive and clarify the relations satisfied by them as direct consequences of the symmetries and the equations of motion in QCD, and connections to the generalized parton distributions. Our results reveal the connections between the gravitational form factors and the higher-twist quark-gluon correlation effects inside the hadrons.

This paper reports measurements of final-state proton multiplicity, muon and proton kinematics, and their correlations in charged-current pionless neutrino interactions, measured by the T2K ND280 near detector in its plastic scintillator (${\mathrm{C}}_8{\mathrm{H}}_8$) target. The data were taken between years 2010 and 2013, corresponding to approximately $6\times {10}^{20}$ protons on target. Thanks to their exploration of the proton kinematics and of imbalances between the proton and muon kinematics, the results offer a novel probe of the nuclear-medium effects most pertinent to the (sub-)GeV neutrino-nucleus interactions that are used in accelerator-based long-baseline neutrino oscillation measurements. These results are compared to many neutrino-nucleus interaction models which all fail to describe at least part of the observed phase space. In case of events without a proton above a detection threshold in the final state, a fully consistent implementation of the local Fermi gas model with multinucleon interactions gives the best description of the data. In the case of at least one proton in the final state, the spectral function model agrees well with the data, most notably when measuring the kinematic imbalance between the muon and the proton in the plane transverse to the incoming neutrino. Within the models considered, only the existence of multinucleon interactions are able to describe the extracted cross section within regions of high transverse kinematic imbalance. The effect of final-state interactions is also discussed.

We study measures of quantum information when the space spanned by the set of accessible observables is not closed under products, i.e., we consider systems where an observer may be able to measure the expectation values of two operators, $⟨O_1⟩$ and $⟨O_2⟩$, but may not have access to $⟨O_1{O}_2⟩$. This problem is relevant for the study of localized quantum information in gravity since the set of approximately local operators in a region may not be closed under arbitrary products. While we cannot naturally associate a density matrix with a state in this setting, it is still possible to define a modular operator for a state, and distinguish between two states using a relative modular operator. These operators are defined on a “little Hilbert space,” which parametrizes small deformations of the system away from its original state, and they do not depend on the structure of the full Hilbert space of the theory. We extract a class of relative-entropy-like quantities from the spectrum of these operators that measure the distance between states, are monotonic under contractions of the set of available observables, and vanish only when the states are equal. Consequently, these distance measures can be used to define measures of bipartite and multipartite entanglement. We describe applications of our measures to “coarse-grained” and “fine-grained” subregion dualities in $\mathrm{AdS}/\mathrm{CFT}$ and provide a few sample calculations to illustrate our formalism.

Using gauge/gravity duality as a tool, we compute the strong sector, isospin-breaking induced contribution to the neutron-proton mass difference in the Witten-Sakai-Sugimoto model of large $N$ QCD with two nondegenerate light flavors. The mass difference, for which we provide an analytic expression, turns out to be positive and proportional to the down-up quark mass splitting, consistently with expectations and previous estimates based on effective QCD models. Extrapolating the model parameters to fit QCD hadronic observables, we find that the strong sector contribution to the nucleon mass splitting overcomes the electromagnetic contribution and is about 0.25% of the average nucleon mass in the model, a result which approaches recent lattice QCD estimates. Our formula is extended to resonances and $\mathrm{\Delta }$ baryons. We thus use it to compute the strong sector contribution to $\mathrm{\Delta }$ baryons mass differences. Finally, we also provide details of how isospin breaking affects the holographic instanton solution describing the baryons.

We discuss a novel scenario for early cosmology, when the inflationary quasi–de Sitter phase dynamically originates from the initial quantum state represented by the microcanonical density matrix. This genuine quantum effect occurs as a result of the dynamics of the topologically nontrivial sectors in a (conjectured) strongly coupled QCD-like gauge theory in expanding universe. The crucial element of our proposal is the presence in our framework of a nontrivial ${\mathbb{S}}^1$ which plays the dual role in construction: it defines the periodic gravitational instanton (on the gravity side) and it also defines a nontrivial gauge holonomy (on the gauge side) generating the vacuum energy. The effect is global in nature and cannot be formulated in terms of a gradient expansion in an effective local field theory. We also discuss a graceful exit from holonomy inflation due to the helical instability. The number of $e$-folds in the holonomy inflation framework is determined by the gauge coupling constant at the moment of inflation, and estimated as $N_{\mathrm{infl}}\sim {\alpha }^{-2}(H_0)\sim {10}^2$. We also comment on the relation of our framework with the no-boundary and tunneling cosmological proposals and their recent criticism.

The aim of this work is to study the entanglement harvesting between two graphene layers inside a planar microcavity. Applying time-dependent perturbation theory it is shown that nonclassical correlations between electrons in different layers are obtained through the exchange of virtual photons. Considering different initial states of the electrons and the vacuum state of the electromagnetic field, the negativity measure that quantifies the entanglement is computed through the photon propagator for time scales smaller than the light-crossing time of the double layer. The results are compared with those obtained for hydrogenic probes and pointlike Unruh-DeWitt detectors, showing that for different initial states, entangled $X$ states and more general entangled reduced matrices are obtained, which enlarge the classification of bipartite quantum states.

In this paper, we have established an asymptotically conical Morris-Thorne wormhole solution that is supported by an anisotropic matter fluid and a global monopole charge in the framework of a $1+3$ dimensional gravity that is minimally coupled to a triplet of scalar fields ${\varphi }^a$, which results from the breaking of a global $O(3)$ symmetry. For the anisotropic matter fluid, we have considered the equation of state (EoS) given by ${\mathcal{P}}_r=\omega \rho$, with a consequence $\omega <-1$, that implies a so-called phantom energy at the throat of the wormhole, which violates the energy conditions. In addition, we study the weak gravitational lensing effect using the Gauss-Bonnet theorem (GBT) applied to the wormhole optical geometry. We show that the total deflection angle consists of a term given by $4{\pi }^2{\eta }^2$, which is independent of the impact parameter $b$, and an additional term, which depends on the radius of the wormhole throat $b_0$ as well as the dimensionless constant $\zeta$.