A new estimation of the isotropic diffuse $\gamma$-ray background (IGRB) observed by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) has been presented for 50 months of data, in the energy range 100 MeV–820 GeV and for different modelings of the Galactic foreground. We attempt here the interpretation of the Fermi-LAT IGRB data in terms of the $\gamma$-ray unresolved emission from different extragalactic populations. We find very good fits to the experimental IGRB, obtained with theoretical predictions for the emission from active galactic nuclei and star-forming galaxies. In addition, we probe a possible emission coming from the annihilation of weakly interacting dark matter (DM) particles in the halo of our Galaxy. We set stringent limits on its annihilation cross section into $\gamma$ rays, which are about the thermal relic value for a wide range of DM masses. We also identify regions in the DM mass and annihilation cross section parameter space which can significantly improve the fit to the IGRB data. Our analysis is conducted within the different IGRB data sets obtained from different models for the Galactic emission, which is shown to add a significant ambiguity on the IGRB interpretation.

Pulsars apparently missing from the Galactic center could have been destroyed by asymmetric fermionic dark matter ($m_X=1–100\mathrm{GeV}$) coupled to a light scalar ($m_{\varphi }=5–20\mathrm{MeV}$), which mixes with the Higgs boson. We point out that this pulsar-collapsing dark sector can resolve the core-cusp problem and will either be excluded or discovered by upcoming direct detection experiments. Another implication is a maximum pulsar age curve that increases with distance from the Galactic center, with a normalization that depends on the couplings and masses of dark sector particles. In addition, we use old pulsars outside the Galactic center to place bounds on asymmetric Higgs portal models.

We explore the use of “optimized” operators, designed to interpolate only a single meson eigenstate, in three-point correlation functions with a vector-current insertion. These operators are constructed as linear combinations in a large basis of meson interpolating fields using a variational analysis of matrices of two-point correlation functions. After performing such a determination at both zero and nonzero momentum, we compute three-point functions and are able to study radiative transition matrix elements featuring excited-state mesons. The required two- and three-point correlation functions are efficiently computed using the distillation framework in which there is a factorization between quark propagation and operator construction, allowing for a large number of meson operators of definite momentum to be considered. We illustrate the method with a calculation using anisotopic lattices having three flavors of dynamical quark all tuned to the physical strange quark mass, considering form factors and transitions of pseudoscalar and vector meson excitations. The dependence on photon virtuality for a number of form factors and transitions is extracted, and some discussion of excited-state phenomenology is presented.

In this paper we study the double $J/\psi$ production in central diffractive processes considering the resolved Pomeron model. Based on the nonrelativistic QCD factorization formalism for the quarkonium production mechanism we estimate the rapidity and transverse momentum dependence of the cross section for the double $J/\psi$ production in diffractive processes at LHC energies. The contributions of the color-singlet and color-octet channels are estimated and predictions for the total cross sections in the kinematical regions of the LHC experiments are also presented. Our results demonstrate that the contribution of central diffractive processes is not negligible and that its study can be useful to test the resolved Pomeron model.

We introduce a modified factorization formalism in quantum chromodynamics for hadronic production of $W$ and $Z$ bosons at large transverse momentum $p_T$. When $p_T$ is much larger than the invariant mass $Q$ of the vector boson, this new factorization formalism systematically resums the large fragmentation logarithms, ${\alpha }_s^m{\ln }^m(p_T^2/Q^2)$, to all orders in the strong coupling ${\alpha }_s$. Using our modified factorization formalism, we present the next-to-leading-order (NLO) predictions for $W$ and $Z$ boson production at high $p_T$ at the CERN Large Hadron Collider and at a future 100 TeV proton-proton collider. Our NLO results are about 5% larger in normalization, and they show improved convergence and moderate reduction of the scale variation compared to the NLO predictions derived in a conventional fixed-order perturbative expansion.

We address the issue of the all order multiplicative renormalizability of $SU(2)$ Yang-Mills theories quantized in the maximal Abelian gauge in presence of scalar matter fields. The nonlinear character of the maximal Abelian gauge requires the introduction of quartic interaction terms in the Faddeev-Popov ghosts, a well-known feature of this gauge. We show that, when scalar matter fields are introduced, a second quartic interaction term between scalar fields and Faddeev-Popov ghosts naturally arises. A Becchi-Rouet-Stora-Tyutin invariant action accounting for those quartic interaction terms is identified and proven to be multiplicative renormalizable to all orders by means of the algebraic renormalization procedure.

The critical behavior of a relativistic ${\mathbb{Z}}_2$-symmetric Yukawa model at zero temperature and density is discussed for a continuous number of fermion degrees of freedom and of spacetime dimensions, with emphasis on the role played by multimeson exchange in the Yukawa sector. We argue that this should be generically taken into account in studies based on the functional renormalization group, either in four-dimensional high-energy models or in lower-dimensional condensed-matter systems. By means of the latter method, we describe the generation of multicritical models in less than three dimensions, both at infinite and finite numbers of flavors. We also provide different estimates of the critical exponents of the chiral Ising universality class in three dimensions for various field contents, from a couple of massless Dirac fermions down to the supersymmetric theory with a single Majorana spinor.

Lorentz violation is a candidate quantum-gravity signal, and the Standard-Model Extension (SME) is a widely used parametrization of such a violation. In the gravitational SME sector, there is an elusive coefficient for which no effects have been found. This is known as the $t$ puzzle and, to date, it has no compelling explanation. This paper analyzes whether there is a fundamental explanation for the $t$ puzzle. To tackle this question, several approaches are followed. Mainly, redefinitions of the dynamical fields are studied, showing that other SME coefficients can be moved to nongravitational sectors. It is also found that the gravity SME sector can be consistently treated à la Palatini, and that, in the presence of spacetime boundaries, it is possible to correct its action to get the desired equations of motion. Moreover, through a reformulation as a Lanczos-type tensor, some problematic features of the $t$ term, which should arise at the phenomenological level, are revealed. The most important conclusion of the paper is that there is no evidence of a fundamental explanation for the $t$ puzzle, suggesting that it may be linked to the approximations taken at the phenomenological level.

We present some new derivations of the effect of a plane gravitational wave on a light ray. A simple interpretation of the results is that a gravitational wave causes a phase modulation of electromagnetic waves. We arrive at this picture from two contrasting directions, namely, null geodesics and Maxwell’s equations, or geometric and wave optics. Under geometric optics, we express the geodesic equations in Hamiltonian form and solve perturbatively for the effect of gravitational waves. We find that the well-known time-delay formula for light generalizes trivially to massive particles. We also recover, by way of a Hamilton-Jacobi equation, the phase modulation obtained under wave optics. Turning then to wave optics—rather than solving Maxwell’s equations directly for the fields, as in most previous approaches—we derive a perturbed wave equation (perturbed by the gravitational wave) for the electromagnetic four-potential. From this wave equation it follows that the four-potential and the electric and magnetic fields all experience the same phase modulation. Applying such a phase modulation to a superposition of plane waves corresponding to a Gaussian wave packet leads to time delays.

We study braneworld models in the presence of scalar field in a five-dimensional geometry with a single extra dimension of infinite extent, with gravity modified to include a function of the Ricci scalar. We develop a procedure that allows us to obtain an analytical solution for the braneworld configuration in a diversity of models, in the much harder case where the Ricci scalar is a nonconstant quantity.

Canonical quantization of spherically symmetric space-times is carried out, using real-valued densitized triads and extrinsic curvature components, with specific factor-ordering choices ensuring in an anomaly free quantum constraint algebra. Comparison with previous work [Nucl. Phys. B399, 211 (1993)] reveals that the resulting physical Hilbert space has the same form, although the basic canonical variables are different in the two approaches. As an extension, holonomy modifications from loop quantum gravity are shown to deform the Dirac space-time algebra, while going beyond “effective” calculations.

We present the affine coherent state quantization of the Bianchi I model. As in our previous paper on quantum theory of Friedmann models, we employ a variable associated with a perfect fluid to play a role of clock. Then we deparametrize the model. A distinctive feature, absent in isotropic models, is an extra nonholonomic constraint, which survives the deparametrization and constrains the range of physical variables. The appearance of the constraint reflects the “amplification” of singularity due to anisotropy. The quantization smoothes the extra constraint and allows quantum contracting trajectories to be smoothly transformed into expanding ones. Making use of an affine coherent state we develop a semiclassical description. Figures are included to illustrate our result.

We argue that a microscopic structure for spacetime such as that expected in a quantum foam scenario, in which microscopic wormholes and other topological structures should play a relevant role, might lead to an effective metric-affine geometry at larger scales. This idea is supported by the role that microscopic defects play in crystalline structures. With an explicit model, we show that wormhole formation is possible in a metric-affine scenario, where the wormhole and the matter fields play a role analogous to that of defects in crystals. Such wormholes also arise in Born-Infeld gravity, which is favored by an analogy with the estimated mass of a point defect in condensed matter systems. We also point out that in metric-affine geometries, Einstein’s equations with an effective cosmological constant appear as an attractor in the vacuum limit for a vast family of theories of gravity. This illustrates how lessons from solid state physics can be useful in unveiling the properties of the microcosmos and defining new avenues for modified theories of gravity.

We consider an inflection point inflationary model in supergravity with a single chiral superfield and show that the predicted values of the scalar spectral index and tensor-to-scalar ratio are consistent with the Planck 2015 results. In this model supersymmetry is strongly broken after inflation, which results in a non-supersymmetry de Sitter vacuum responsible for the recent accelerated expansion of the Universe.

A cosmological gauge field with isotropic stress-energy introduces parity violation into the behavior of gravitational waves. We show that a primordial spectrum of inflationary gravitational waves develops a preferred handedness, left or right circularly polarized, depending on the abundance and coupling of the gauge field during the radiation era. A modest abundance of the gauge field would induce parity-violating correlations of the cosmic microwave background temperature and polarization patterns that could be detected by current and future experiments.

In light of the history of research on an electromagnetic wave spectrum, a sharp emission line of gravitational wave background (GWB) would be an interesting observational target. Here we study an efficient method to detect a line GWB by correlating data of multiple ground-based detectors. We find that the width of frequency bin for coarse graining is a critical parameter, and, with the commonly used value 0.25 Hz, the signal-to-noise ratio could be decreased by up to a factor of 6.6, compared with a finer width of 0.02 Hz. By reanalyzing the existing data with a smaller bin width, we might detect a precious line signal from the early Universe.

A recent article by Wojtak et al. pointed out that the local gravitational redshift, despite its smallness ($\sim {10}^{-5}$), can have a noticeable ($\sim 1\%$) systematic effect on our cosmological parameter measurements. The authors studied a few extended cosmological models (nonflat $\mathrm{\Lambda }\mathrm{CDM}$, $w\mathrm{CDM}$, and $w_0$-$w_a\mathrm{CDM}$) with a mock supernova data set. We repeat this calculation and find that the $\sim 1\%$ biases are due to strong degeneracy between cosmological parameters. When cosmic microwave background (CMB) data are added to break the degeneracy, the biases due to local gravitational redshift are negligible ($\lesssim 0.1\sigma$).

We present a high-quality description of the deuteron electromagnetic form factors in a soft-wall anti-de Sitter/quantum chromodynamics approach. We first propose an effective action describing the dynamics of the deuteron in the presence of an external vector field. Based on this action the deuteron electromagnetic form factors are calculated, displaying the correct $1/Q^{10}$ power scaling for large $Q^2$ values. This finding is consistent with quark counting rules and the earlier observation that this result holds in confining gauge/gravity duals. The $Q^2$ dependence of the deuteron form factors is defined by a single and universal scale parameter $\kappa$, which is fixed from data.

Using a sample of 1.31 billion $J/\psi$ events accumulated with the BESIII detector at the BEPCII collider, we report the observation of the decay $J/\psi \to \varphi {\pi }^0$, which is the first evidence for a doubly Okubo–Zweig–Iizuka suppressed electromagnetic $J/\psi$ decay. A clear structure is observed in the $K^{+}{K}^{-}$ mass spectrum around $1.02\mathrm{GeV}/c^2$, which can be attributed to interference between $J/\psi \to \varphi {\pi }^0$ and $J/\psi \to K^{+}{K}^{-}{\pi }^0$ decays. Due to this interference, two possible solutions are found. The corresponding measured values of the branching fraction of $J/\psi \to \varphi {\pi }^0$ are $[2.94\pm 0.16(\mathrm{stat})\pm 0.16(\mathrm{syst})]\times 10^{-6}$ and $[1.24\pm 0.33(\mathrm{stat})\pm 0.30(\mathrm{syst})]\times 10^{-7}$.

In this work we study implications of additional nonholomorphic soft breaking terms (${\mu }^{\prime }$, $A_t^{\prime }$, $A_b^{\prime }$, and $A_{\tau }^{\prime }$) on the minimal supersymmetric extension of the standard model (MSSM) phenomenology. By respecting the existing bounds on the mass measurements and restrictions coming from certain B-decays, we probe reactions of the MSSM to these additional soft breaking terms. We provide examples in which some slightly excluded solutions of the MSSM can be made to be consistent with the current experimental results. During this, even after applying additional fine-tuning constraints, the nonholomorphic terms are allowed to be as large as hundreds of GeV. Such terms prove that they are capable of enriching the phenomenology and varying the mass spectra of the MSSM heavily, with a reasonable amount of fine-tuning. We observe that Higgsinos, the lightest stop, the heavy Higgs boson states $A,H,H^{\pm }$, sbottom and stau exhibit the highest sensitivity to the new terms. We also show how the light stop can become nearly degenerate with top quark using these nonholomorphic terms.