We consider a flat Universe filled with a vacuum energy coupled to matter and radiation by respectively positive coupling functions $Q_m$ and $Q_r$. We require that these functions be such as Universe exits from inflation to go to a radiation dominated epoch and allow us to reproduce the observed $\mathrm{\Lambda }\mathrm{CDM}$ expansion after this last epoch. These requirements lead to some necessary constraints on the coupling functions. We then look at one of the simplest forms of $Q_m$ and $Q_r$ able to satisfy them. The cosmological model thus defined describes a Universe with an initial singularity and endless alternated periods of accelerated and decelerated expansion (one of them being our $\mathrm{\Lambda }\mathrm{CDM}$ Universe) unifying inflation and present time expansion acceleration.

We established the allowed parameters of the two-Higgs-doublet model (2HDM) from flavor physics observables—more precisely, from rare $B$-meson decays. In our analysis, the most formidable constraints on the 2HDM parameters arise from the branching ratio of rare radiative $B$-meson decay, i.e. $B\to X_s\gamma$. However, the constraints arising from the branching ratio of $B_s\to {\mu }^{+}{\mu }^{-}$ decay in the $m_{H^{\pm }}\text{−}\tan \beta$ plane give $m_{H^{\pm }}>80\mathrm{GeV}$ for the value of $\tan \beta \sim 2$, which is in agreement with large electron-positron collider (LEP) data. Furthermore, we also investigate the bounds on the $CP$-even $m_H$ and $CP$-odd $m_{A^0}$ Higgs boson not only from the above mentioned physical observables, but also from the zero crossing of the forward-backward asymmetry of $B\to K^{*}{\mu }^{+}{\mu }^{-}$ decay. Therefore, these bounds on parameters of the 2HDM will provide fertile ground to test the 2HDM at current and future $B$-physics experiments.

We examine if the cosmological relaxation mechanism, which was proposed recently as a new solution to the hierarchy problem, can be compatible with high reheating temperature well above the weak scale. As the barrier potential disappears at high temperature, the relaxion rolls down further after the reheating, which may ruin the successful implementation of the relaxation mechanism. It is noted that if the relaxion is coupled to a dark gauge boson, the new frictional force arising from dark gauge boson production can efficiently slow down the relaxion motion, which allows the relaxion to be stabilized after the electroweak phase transition for a wide range of model parameters, while satisfying the known observational constraints.

We calculate the prominent perturbative contributions shaping the one-loop scalar spectrum of the minimal renormalizable nonsupersymmetric $SO(10)$ Higgs model whose unified gauge symmetry is spontaneously broken by an adjoint scalar. Focusing on its potentially realistic $45\oplus 126$ variant in which the rank is reduced by a vacuum expectation value of the 5-index antisymmetric self-dual tensor, we provide a thorough analysis of the corresponding Coleman-Weinberg one-loop effective potential, paying particular attention to the masses of the potentially tachyonic pseudo-Goldstone bosons transforming as (1, 3, 0) and (8, 1, 0) under the standard model (SM) gauge group. The results confirm the assumed existence of extended regions in the parameter space supporting a locally stable SM-like quantum vacuum inaccessible at the tree level. The effective potential tedium is compared to that encountered in the previously studied $45\oplus 16$ $SO(10)$ Higgs model where the polynomial corrections to the relevant pseudo-Goldstone masses turn out to be easily calculable within a very simplified purely diagrammatic approach.

Recently, a new family of observables consisting of azimuthal-angle generalized ratios was proposed in a kinematical setup that resembles the usual Mueller-Navelet jets but with an additional tagged jet in the central region of rapidity. Nontagged minijet activity between the three jets can affect significantly the azimuthal angle orientation of the jets and is accounted for by the introduction of two Balitsky-Fadin-Kuraev- Lipatov (BFKL) gluon Green functions. Here, we calculate the, presumably, most relevant higher order corrections to the observables by now convoluting the three leading order jet vertices with two gluon Green functions at next-to-leading logarithmic approximation. The corrections appear to be mostly moderate, giving us confidence that the recently proposed observables are actually an excellent way to probe the BFKL dynamics at the LHC. Furthermore, we allow for the jets to take values in different rapidity bins in various configurations such that a comparison between our predictions and the experimental data is a straightforward task.

We extract polarized parton distribution functions (PPDFs), referred to as “KTA17,” together with the highly correlated strong coupling ${\alpha }_s$ from recent and up-to-date $g_1$ and $g_2$ polarized structure functions world data at next-to-next-to-leading order in perturbative QCD. The stability and reliability of the results are ensured by including nonperturbative target mass corrections as well as higher-twist terms which are particularly important at the large-$x$ region at low ${\mathrm{Q}}^2$. Their role in extracting the PPDFs in the nucleon is studied. Sum rules are discussed and compared with other results from the literature. This analysis is made by means of the Jacobi polynomials expansion technique to the DGLAP evolution. The uncertainties on the observables and on the PPDFs throughout this paper are computed using standard Hessian error propagation which served to provide a more realistic estimate of the PPDFs uncertainties.

The capabilities of liquid argon time projection chambers (LArTPCs) to reconstruct the spatial and calorimetric information of neutrino events have made them the detectors of choice in a number of experiments, specifically those looking to observe electron neutrino (${\nu }_e$) appearance. The LArTPC promises excellent background rejection capabilities, especially in this “golden” channel for both short and long baseline neutrino oscillation experiments. We present the first experimental observation of electron neutrinos and antineutrinos in the ArgoNeut LArTPC, in the energy range relevant to DUNE and the Fermilab Short Baseline Neutrino Program. We have selected 37 electron candidate events and 274 gamma candidate events, and measured an 80% purity of electrons based on a topological selection. Additionally, we present a separation of electrons from gammas using calorimetric energy deposition, demonstrating further separation of electrons from background gammas.

Using 106 $\times 10^6$ $\psi (3686)$ events collected with the BESIII detector, we measure multipole amplitudes for the decay $\psi (3686)\to \gamma {\chi }_{c1,2}\to \gamma \gamma J/\psi$ beyond the dominant electric-dipole amplitudes. The normalized magnetic-quadrupole (M2) amplitude for $\psi (3686)\to \gamma {\chi }_{c1,2}\to \gamma \gamma J/\psi$ and the normalized electric-octupole amplitudes for $\psi (3686)\to \gamma {\chi }_{c2}$, ${\chi }_{c2}\to \gamma J/\psi$ are determined. The M2 amplitudes for $\psi (3686)\to \gamma {\chi }_{c1}$ and ${\chi }_{c1,2}\to \gamma J/\psi$ are found to differ significantly from zero and are consistent with theoretical predictions. We also obtain the ratios of M2 contributions of $\psi (3686)$ and $J/\psi$ decays to ${\chi }_{c1,2}$, $b_2^1/b_2^2=1.35\pm 0.72$ and $a_2^1/a_2^2=0.617\pm 0.083$, which agree well with theoretical expectations. By considering the multipole contributions of ${\chi }_{c1,2}$, we measure the product branching fractions for the cascade decays $\psi (3686)\to \gamma {\chi }_{c0,1,2}\to \gamma \gamma J/\psi$ and search for the process ${\eta }_c(2S)\to \gamma J/\psi$ through $\psi (3686)\to \gamma {\eta }_c(2S)$. The product branching fraction for $\psi (3686)\to \gamma {\chi }_{c0}\to \gamma \gamma J/\psi$ is $3\sigma$ larger than published measurements, while those of $\psi (3686)\to \gamma {\chi }_{c1,2}\to \gamma \gamma J/\psi$ are consistent. No significant signal for the decay $\psi (3686)\to \gamma {\eta }_c(2S)\to \gamma \gamma J/\psi$ is observed, and the upper limit of the product branching fraction at the 90% confidence level is determined.

The discrete Frenet equation entails a local framing of a discrete, piecewise linear polygonal chain in terms of its bond and torsion angles. In particular, the tangent vector of a segment is akin to the classical O(3) spin variable. Thus there is a relation to the lattice Heisenberg model that can be used to model physical properties of the chain. On the other hand, the Heisenberg model is closely related to the discrete nonlinear Schrödinger equation. Here we apply these interrelations to develop a perspective on discrete chains dynamics: We employ the properties of a discrete chain in terms of a spinorial representation of the discrete Frenet equation, to introduce a bi-Hamiltonian structure for the discrete nonlinear Schrödinger equation, which we then use to produce integrable chain dynamics.

Neutron-star magnetospheres are structured by very intense magnetic fields extending from 100 to $10^5\mathrm{km}$ traveled by very energetic electrons and positrons with Lorentz factors up to $\sim 10^7$. In this context, particles are forced to travel almost along the magnetic field with very small gyromotion, potentially reaching the quantified regime. We describe the state of Dirac particles in a locally uniform, constant, and curved magnetic field in the approximation that the Larmor radius is very small compared to the radius of curvature of the magnetic field lines. We obtain a result that admits the usual relativistic Landau states as a limit of null curvature. We will describe the radiation of these states, which we call quantum curvature or synchrocurvature radiation, in an upcoming paper.

We investigate the critical properties of the Lee-Yang model in less than six spacetime dimensions using truncations of the functional renormalization group flow. We give estimates for the critical exponents, study the dependence on the regularization scheme, and show the convergence of our results for increasing size of the truncations in four and five dimensions. While with our truncations it is numerically challenging to approach the three-dimensional case, we provide a simple approximation which allows us to qualitatively study the Lee-Yang model in two and three dimensions and use it to argue the existence of further nonunitary multicritical theories including one which is relevant for the universality class of the Blume-Capel model.

Nowadays, thanks to the improved precision of cosmological data, it has become possible to search for deviation from the general relativity theory with tests on large cosmic scales. Particularly, there is a class of modified gravity theories that breaks the Einstein equivalence principle (EEP) in the electromagnetic sector, generating variations of the fine structure constant, violations of the cosmic distance duality relation, and the evolution law of cosmic microwave background (CMB) radiation. In recent papers, this class of theories has been tested with angular diameter distances from galaxy clusters, type Ia supernovae, and CMB temperature. In this work we propose a new test by considering the most recent x-ray surface brightness observations of galaxy clusters jointly with type Ia supernovae and CMB temperature. The crucial point here is that we take into account the dependence of the x-ray gas mass fraction of galaxy clusters on possible variations of the fine structure constant and violations of the cosmic distance duality relation. Our basic result is that this new approach is competitive with the previous one, and it also does not show significant deviations from general relativity.

We compute a subset of three, velocity-independent four-loop (and fourth post-Newtonian) contributions to the harmonic-coordinates effective action of a gravitationally interacting system of two point masses. We find that, after summing the three terms, the coefficient of the total contribution is rational, due to a remarkable cancellation between the various occurrences of ${\pi }^2$. This result, obtained by a classical field-theory calculation, corrects the recent effective-field-theory-based calculation by Foffa et al. [arXiv:1612.00482]. Besides showing the usefulness of the saddle-point approach to the evaluation of the effective action, and of $\mathit{x}$-space computations, our result brings a further confirmation of the current knowledge of the fourth post-Newtonian effective action. We also show how the use of the generalized Riesz formula [Phys. Rev. D 57, 7274 (1998)] allows one to analytically compute a certain four-loop scalar master integral (represented by a four-spoked wheel diagram) which was, so far, only numerically computed.

We investigate the critical behavior of a ($n+1$)-dimensional topological dilaton black holes in an extended phase space in both canonical and grand-canonical ensembles, when the gauge field is in the form of a power-Maxwell field. In order to do this, we introduce for the first time the counterterms that remove the divergences of the action in dilaton gravity for the solutions with curved boundary. Using the counterterm method, we calculate the conserved quantities and the action and, therefore, the Gibbs free energy in both the canonical and grand-canonical ensembles. We treat the cosmological constant as a thermodynamic pressure, and its conjugate quantity as a thermodynamic volume. In the presence of the power-Maxwell field, we find an analogy between the topological dilaton black holes with a van der Walls liquid-gas system in all dimensions provided the dilaton coupling constant $\alpha$ and the power parameter $p$ are chosen properly. Interestingly enough, we observe that the power-Maxwell dilaton black holes admit the phase transition in both canonical and grand-canonical ensembles. This is in contrast to RN-AdS, Einstein-Maxwell-dilaton and Born-Infeld-dilaton black holes, which only admit the phase transition in the canonical ensemble. In addition, we calculate the critical quantities and show that they depend on $\alpha$, $n$ and $p$. Finally, we obtain the critical exponents in the two ensembles and show that they are independent of the model parameters and have the same values as in the mean-field theory.

We consider a rather simple method for the description of the big bang–big crunch cosmological singularity crossing. For the flat Friedmann universe this method gives the same results as more complicated methods, using Weyl symmetry or the transitions between the Jordan and Einstein frames. It is then easily generalized for the case of a Bianchi-I anisotropic universe. We also present early-time and late-time asymptotic solutions for a Bianchi-I universe, filled with a conformally coupled massless scalar field.

We consider a general stationary solution and derive the general laws for accretion of rotating perfect fluids. For nondegenerate and degenerate Fermi and Bose fluids we derive new effects that mimic the center-of-mass-energy effect of two colliding particles in the vicinity of horizons. Nondegenerate fluids see their chemical potential grow arbitrarily and ultrarelativistic Fermi fluids see their specific enthalpy and Fermi momentum grow arbitrarily too while the latter vanishes gradually for nonrelativistic Fermi fluids. For degenerate Bose fluids two scenarios remain possible as the fluid approaches a horizon: (a) The Bose-Einstein condensation ceases or (b) the temperature drops gradually down to zero. The critical flow is also investigated.

We present constraints on the annihilation cross section of weakly interacting massive particles dark matter based on the joint statistical analysis of four dwarf galaxies with VERITAS. These results are derived from an optimized photon weighting statistical technique that improves on standard imaging atmospheric Cherenkov telescope (IACT) analyses by utilizing the spectral and spatial properties of individual photon events. We report on the results of $\sim 230$ hours of observations of five dwarf galaxies and the joint statistical analysis of four of the dwarf galaxies. We find no evidence of gamma-ray emission from any individual dwarf nor in the joint analysis. The derived upper limit on the dark matter annihilation cross section from the joint analysis is $1.35\times {10}^{-23}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ at 1 TeV for the bottom quark ($b\overline{b}$) final state, $2.85\times {10}^{-24}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ at 1 TeV for the tau lepton (${\tau }^{+}{\tau }^{-}$) final state and $1.32\times {10}^{-25}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ at 1 TeV for the gauge boson ($\gamma \gamma$) final state.

We revisit the proof of the perturbative QCD factorization for the exclusive processes $\rho {\gamma }^{\star }\to \pi (\rho )$ at the two-parton twist-3 level. It is pointed out that the residual collinear divergences observed in the literature, which break the factorization of the above processes at the considered accuracy, are attributed to the improper insertion of the Fierz identity for factorizing the fermion flow. We show that the factorization theorem indeed holds at the two-parton twist-3 level after the mishandling is corrected.

We consider a vectorlike gauge theory of fermions that confines at the multi-TeV scale, and that realizes the Higgs particle as a composite Goldstone boson. The weak interactions are embedded in the unbroken subgroup $Sp(4)$ of a spontaneously broken $SU(4)$ flavor group. The meson resonances appear as poles in the two-point correlators of fermion bilinears, and include the Goldstone bosons plus a massive pseudoscalar ${\eta }^{\prime }$, as well as scalars, vectors and axial vectors. We compute the mass spectrum of these mesons, as well as their decay constants, in the chiral limit, in the approximation where the hypercolor $Sp(2N)$ dynamics is described by four-fermion operators, à la Nambu-Jona Lasinio. By resumming the leading diagrams in the $1/N$ expansion, we find that the spin-one states lie beyond the LHC reach, while spin-zero electroweak-singlet states may be as light as the Goldstone-boson decay constant, $f\sim 1\mathrm{TeV}$. We also confront our results with a set of available spectral sum rules. In order to supply composite top-quark partners, the theory contains additional fermions carrying both hypercolor and ordinary color, with an associated flavor symmetry-breaking pattern $SU(6)/SO(6)$. We identify and analyze several nontrivial features of the complete two-sector gauge theory: the ’t Hooft anomaly matching conditions; the higher-dimension operator which incorporates the effects of the hypercolor axial-singlet anomaly; the coupled mass-gap equations; the mixing between the singlet mesons of the two sectors, resulting in an extra Goldstone boson ${\eta }_0$, and novel spectral sum rules. Assuming that the strength of the four-fermion interaction is the same in the two sectors, we find that the colored vector and scalar mesons have masses $\gtrsim 4f$, while the masses of colored pseudo-Goldstone bosons, induced by gluon loops, are $\gtrsim 1.5f$. We discuss the scaling of the meson masses with the values of $N$, of the four-fermion couplings, and of a possible fermion mass.