We discuss the dimensional reduction of five-dimensional supergravity compactified on $S^1/Z_2$ keeping the $N=1$ off-shell structure. In particular, we clarify the roles of the $Z_2$-odd $N=1$ multiplets in such an off-shell dimensional reduction. Their equations of motion provide constraints on the $Z_2$-even multiplets and extract the zero modes from the latter. The procedure can be applied to a wide range of models and performed in a background-independent way. We demonstrate it in some specific models.

We report the results of searches for $B^{+}\to J/\psi {\eta }^{\prime }{K}^{+}$ and $B^0\to J/\psi {\eta }^{\prime }{K}_S^0$ decays, using a sample of $388\times {10}^6$ $B\overline{B}$ pairs collected with the Belle detector at the ${\rm Y}(4S)$ resonance. No statistically significant signal is found for either of the two decay modes and upper limits for the branching fractions are determined to be $\mathcal{B}(B^{+}\to J/\psi {\eta }^{\prime }{K}^{+})<8.8\times {10}^{-5}$ and $\mathcal{B}(B^0\to J/\psi {\eta }^{\prime }{K}_S^0)<2.5\times {10}^{-5}$ at 90% confidence level.

The axial-vector meson $K_1(1270)$ was studied within the chiral unitary approach, where it was shown that it has a two-pole structure. We reanalyze the high-statistics WA3 experiment $K^{-}p\to K^{-}{\pi }^{+}{\pi }^{-}p$ at 63 GeV, which established the existence of both $K_1(1270)$ and $K_1(1400)$, and we show that it clearly favors our two-pole interpretation. We also reanalyze the traditional $K$-matrix interpretation of the WA3 data and find that the good fit of the data obtained there comes from large cancellations of terms of unclear physical interpretation.

We use a multiply-subtracted Omnès dispersion relation for the form factor $f^{+}$ in $B\to \pi$ semileptonic decay, allowing the direct input of experimental and theoretical information to constrain its dependence on $q^2$, thereby improving the precision of the extracted value of $|V_{ub}|$. Apart from these inputs we use only unitarity and analyticity properties. We obtain $|V_{ub}|=(4.02\pm 0.35)\times {10}^{-3}$, improving the agreement with the value determined from inclusive methods, and competitive in precision with them.

We present a complete next-to-leading-order (NLO) calculation for the total cross section of inclusive Higgs pair production via bottom-quark fusion $(b\overline{b}\to hh)$ at the CERN Large Hadron Collider (LHC) in the standard model. The NLO QCD corrections lead to less dependence on the renormalization scale (${\mu }_R$) and the factorization scale (${\mu }_F$) than the leading-order (LO) cross section, and they significantly increase the LO cross section. The rate for inclusive Higgs pair production is small in the standard model, but can be large in models with enhanced couplings of the $b$ quark to the Higgs bosons.

We construct explicit Einstein-Kähler metrics in all even dimensions $D=2n+4\ge 6$, in terms of a $2n$-dimensional Einstein-Kähler base metric. These are cohomogeneity 2 metrics which have the new feature of including a NUT-type parameter, or gravomagnetic charge, in addition to.." in addition to mass and rotation parameters. Using a canonical construction, these metrics all yield Einstein-Sasaki metrics in dimensions $D=2n+5\ge 7$. As is commonly the case in this type of construction, for suitable choices of the free parameters the Einstein-Sasaki metrics can extend smoothly onto complete and nonsingular manifolds, even though the underlying Einstein-Kähler metric has conical singularities. We discuss some explicit examples in the case of seven-dimensional Einstein-Sasaki spaces. These new spaces can provide supersymmetric backgrounds in M theory, which play a rôle in the ${\mathrm{AdS}}_4/{\mathrm{CFT}}_3$ correspondence.

We introduce the $D=4$ twistorial tensionfull bosonic string by considering the canonical twistorial 2-form in two-twistor space. We demonstrate its equivalence to two bosonic string models: due to Siegel (with covariant world-sheet vectorial string momenta $P_{\mu }^m(\tau ,\sigma )$) and the one with tensorial string momenta $P_{[\mu \nu ]}(\tau ,\sigma )$. We show how to obtain in mixed spacetime-twistor formulation the Soroka-Sorokin-Tkach-Volkov (SSTV) string model and subsequently by harmonic gauge fixing the Bandos-Zheltukhin (BZ) model, with constrained spinorial coordinates.

Pseudo-Goldstone bosons in 4D strongly coupled theories have a dual description in terms of 5D gauge theories in warped backgrounds. We introduce systematic methods of computing the pseudo-Goldstone potential for an arbitrary warp factor in 5D. When applied to electroweak symmetry breaking, our approach clarifies the relation of physical observables to geometrical quantities in five dimensions.

We present an analysis of well-posedness of constrained evolution of $3+1$ formulations of general relativity. In this analysis we explicitly take into account the energy and momentum constraints as well as possible algebraic constraints on the evolution of high-frequency perturbations of solutions of Einstein’s equations. In this respect, our approach is principally different from standard analyses of well-posedness of free evolution in general relativity. Our study reveals the existence of subsets of the linearized Einstein’s equations that control the well-posedness of constrained evolution. It is demonstrated that the well-posedness of Arnowitt-Deser-Misner (ADM), Baumgarte-Shapiro-Shibata-Nakamura and other $3+1$ formulations derived from the ADM formulation by adding combinations of constraints to the right-hand side of the ADM formulation and/or by linear transformation of the dynamical ADM variables depends entirely on the properties of the gauge. For certain classes of gauges we formulate conditions for well-posedness of constrained evolution. This provides a new basis for constructing stable numerical integration schemes for a classical ADM and many other $3+1$ formulations of general relativity.

We show that the second accelerating expansion of the universe appears smoothly from the decelerating phase, which follows the initial inflation, in the two-dimensional soluble semiclassical dilaton gravity along with the modified Poisson brackets with noncommutativity between the relevant fields. This is in contrast to the fact that the ordinary solution of the equations of motion following from the conventional Poisson algebra describes a permanent accelerating universe without any phase change. In this modified model, it turns out that the noncommutative Poisson algebra is responsible for the remarkable phase transition to the second accelerating expansion.

Recently it has been observed that the group $E_7$ can be used to describe a special type of quantum entanglement of seven qubits partitioned into seven tripartite systems. Here we show that this curious type of entanglement is entirely encoded into the discrete geometry of the Fano plane. We explicitly work out the details concerning a qubit interpretation of the $E_7$ generators as representatives of tripartite protocols acting on the 56-dimensional representation space. Using these results we extend further the recently studied analogy between quantum information theory and supersymmetric black holes in four-dimensional string theory. We point out that there is a dual relationship between entangled subsystems containing three and four tripartite systems. This relationship is reflected in the structure of the expressions for the black hole entropy in the $N=4$ and $N=2$ truncations of the $E_{7(7)}$ symmetric area form of $N=8$ supergravity. We conjecture that a similar picture based on other qubit systems might hold for black hole solutions in magic supergravities.

The van der Waals quintessence equation of state is an interesting scenario for describing the late universe, and seems to provide a solution to the puzzle of dark energy, without the presence of exotic fluids or modifications of the Friedmann equations. In this work, the construction of inhomogeneous compact spheres supported by a van der Waals equation of state is explored. These relativistic stellar configurations shall be denoted as van der Waals quintessence stars. Despite of the fact that, in a cosmological context, the van der Waals fluid is considered homogeneous, inhomogeneities may arise through gravitational instabilities. Thus, these solutions may possibly originate from density fluctuations in the cosmological background. Two specific classes of solutions, namely, gravastars and traversable wormholes are analyzed. Exact solutions are found, and their respective characteristics and physical properties are further explored.

We consider particlelike and black hole solutions of the Einstein-Yang-Mills system with positive cosmological constant in $d>4$ spacetime dimensions. These configurations are spherically symmetric and present a cosmological horizon for a finite value of the radial coordinate, approaching asymptotically the de Sitter background. In the usual Yang-Mills case, we find that the mass of these solutions, evaluated outside the cosmological horizon at future/past infinity, generically diverges for $d>4$. Solutions with finite mass are found by adding to the action higher order gauge field terms belonging to the Yang-Mills hierarchy. A discussion of the main properties of these solutions and their differences from those of the usual Yang-Mills model, both in four and higher dimensions, is presented.

The acceleration of the cosmic expansion may be due to a new component of physical energy density or a modification of physics itself. Mapping the expansion of cosmic scales and the growth of large scale structure in tandem can provide insights to distinguish between the two origins. Using Minimal Modified Gravity (MMG)—a single parameter gravitational growth index formalism to parametrize modified gravity theories—we examine the constraints that cosmological data can place on the nature of the new physics. For next generation measurements combining weak lensing, supernovae distances, and the cosmic microwave background we can extend the reach of physics to allow for fitting gravity simultaneously with the expansion equation of state, diluting the equation of state estimation by less than 25% relative to when general relativity is assumed, and determining the growth index to 8%. For weak lensing we examine the level of understanding needed of quasi- and nonlinear structure formation in modified gravity theories, and the trade off between stronger precision but greater susceptibility to bias as progressively more nonlinear information is used.

We investigate a string-inspired dark energy scenario featuring a scalar field with a coupling to the Gauss-Bonnet invariant. We discuss extensively the cosmological and astrophysical implications of the coupled scalar field. Such coupling can trigger the onset of late dark energy domination after a scaling matter era. The universe may then cross the phantom divide and perhaps also exit from the acceleration. The evolution of fluctuations in the scalar field and their impact on the clustering of matter are studied in detail and model independently. The small-scale limit is derived for the perturbations and their stability is addressed. The general equations for scalar perturbations are also presented and solved numerically, confirming that the Gauss-Bonnet coupling can be compatible with the observed spectrum of cosmic microwave background radiation as well as the matter power spectrum inferred from large-scale surveys. Data from the solar system, supernovae Ia, cosmic microwave background radiation, large-scale structure, and big bang nucleosynthesis are used to constrain the parameters of the model. The geometric constraints from background expansion favor exponential potentials with a shallow slope, which is in tension with the nucleosynthesis bound on early quintessence. Also, high values for the present matter density are required. Including the baryon oscillation scale, one could rule out the model at about 99% confidence level. A discussion of how to overcome such possible problems in more elaborate models is included, together with considerations of the validity of these constraints in the present context. Interestingly, one also finds that a good Newtonian limit may require fixing the coupling.

Analytic description of the evolution of cosmic ray showers is dominated by the Greisen equation nearly five decades old. We present an alternative approach with several advantages. Among the new features are a prediction of the differential distribution, replacing Greisen’s form which fails to be positive definite. Explicit comparison with Monte Carlo simulations shows excellent agreement after a few radiation lengths of development. We find a clear connection between Monte Carlo adjustment of Greisen’s form and underlying physics, and present a concise derivation with all steps explicit. We also reconstruct the steps needed to reproduce Greisen’s approximate formula, which appears not to have been published previously.

We study quarkonium correlators and spectral functions at zero and finite temperature using the anisotropic Fermilab lattice formulation with anisotropy $\xi =2$ and 4. To control cut-off effects we use several different lattice spacings. The spectral functions were extracted from lattice correlators with maximum entropy method based on a new algorithm. We find evidence for the survival of $1S$ quarkonium states in the deconfined medium till relatively high temperatures as well as for dissolution of $1P$ quarkonium states right above the deconfinement temperature.

We introduce photons in partially quenched chiral perturbation theory and calculate the resulting electromagnetic loop-corrections at next-to-leading-order (NLO) for the charged meson masses and decay constants. We also present a numerical analysis to indicate the size of the different corrections. We show that several phenomenologically relevant quantities can be calculated consistently with photons which couple only to the valence quarks, allowing the use of gluon configurations produced without dynamical photons.

We calculate the effects of next-to-leading order perturbative QCD as well as of the quark transverse motion and off-shellness on the Drell-Yan process cross section. By studying the $s\to \infty$ behavior of the cross section in these approaches, we find that the effects of quark off-shellness and intrinsic-$k_T$ parametrize those of higher twists. In particular, the off-shellness of partons generates part of the $K$-factor type corrections to the leading order cross section. Higher-twist contributions to the $p_T$-spectrum of the Drell-Yan pairs are found to be large for presently accessible energies. The evolution of quark off-shellness distribution with the hard scale is also studied.