
Oset, E.; Marco, E.; Nacher, J. C.; Oller, J. A.; Peláez Sagredo, José Ramón; Ramos, A.; Toki, H.
By means of a coupled channel nonperturbative unitary approach, it is possible to extend the strong constrains of Chiral Perturbation Theory to higher energies. In particular, it is possible to reproduce the lowest lying resonances in mesonmeson scattering up to 1.2 GeV using the parameters of the O(p²) and O ( p^ 4 ) Chiral Lagrangian. The meson baryon sector can also be tackled along similar lines. We report on an update of these results showing some examples of photon induced reactions where the techniques have been recently applied.

Oller, J. A.; Oset, E.; Guerrero, F.; Peláez Sagredo, José Ramón
A nonperturbative method [1] which combines constraints from chiral symmetry breaking and coupled channel unitarity is used to describe mesonmeson interactions up to √s<_~1.2 GeV, extending in this way the range of applicability of the information contained in Chiral Perturbation Theory (X PT) [2], since this perturbative series is typically restricted to √s<_500 MeV. The approach uses the O(p²) and O(p^4) Lagrangians. The seven free parameters resulting from the O(p^4) Lagrangian are fitted to the experimental data. The approach makes use of the expansion of T^(1) instead of the amplitude itself as done in X PT. The former expansion is...

Oset, E.; Hosaka, A; Nacher, J. C.; Oka, M.; Oller, J. A.; Parreño, A.; Peláez Sagredo, José Ramón; Ramos, A.; Toki, H.
We report on recent progress on the chiral unitary approach, which is shown to have a much larger convergence radius than ordinary chiral perturbation theory, allowing one to reproduce data for meson meson interaction up to 1.2 GeV and meson baryon interaction up to the first baryonic resonances. Applications to physical processes so far unsuited for a standard chiral perturbative approach are presented, concretely the K⁻ p → Λ(1405) γ reaction and the N*(1535) N+(1535) π and η couplings.

Peláez Sagredo, José Ramón
We report on recent progress on the chiral unitary approach, analogous to the effective range expansion in Quantum Mechanics, which is shown to have a much larger convergence radius than ordinary chiral perturbation theory, allowing one to reproduce data for meson meson interaction up to 1.2 GeV. Applications to physical processes so far unsuited for a standard chiral perturbative approach are presented. Results for the extension of these ideas to the meson baryon sector are discussed, together with applications to kaons in a nuclear medium and K⁻ atoms.

Peláez Sagredo, José Ramón; Brodsky, S. J; Merino, C.; Toumbas, N.
We review our recent works on tests of perturbative QCD, inspired by the relation between the hadronic decay of the τ lepton and the e⁺e⁻ annihilation into hadrons. First, we present a set of commensurate scale relations that probe the selfconsistency of leadingtwist QCD predictions for any observable which defines an effective charge. These tests are independent of the renormalization scheme and scale, and are applicable over wide data ranges. As an example we apply this approach to R_e⁺e⁻. Second, using a differential form of these conmensurate scale relations, we present a method to measure the QCD GellMann–Low Ψ function.

Peláez Sagredo, José Ramón; Oller, J. A.; Oset,, E.
By means of a coupled channel nonperturbative unitary approach, it is possible to extend the strong constrains of Chiral Perturbation Theory to higher energies. In particular, it is possible to reproduce the lowest lying resonances in mesonmeson scattering up to 1.2 GeV using the parameters of the O (p²) and O (p⁴) Chiral Lagrangian. We report on an update of these results examining their possible relevance for meson spectroscopy

Martínez Alonso, Luis; Medina Reus, Elena
A scheme for solving quasiclassicalstring equations is developed to prove that genuszero hitham hierarchies describe the deformations of planar domains determined by rational conformalmaps. This property is applied in normal matrix models to show that deformations of simplyconnected supports of eigenvalues under changes of coupling constants are governed by genuszero Whitham hierarchies.

Martínez Alonso, Luis; Medina Reus, Elena
In this work we use RiemannHilbert problems for multiple orthogonal polynomials in order to derive string equations associated to LaxOrlov pairs operators. These string equations provide us with a useful tool to analyze the large nlimit of the related hierarchies. The results are finally applied to the study of the associated random matrix models (Gaussian Hermitian matrix models with an external source) and nonintersecting Brownian motions starting from a fix point.

Finkel Morgenstern, Federico; González López, Artemio
The aim of this paper is studying from an alternative point of view the integrability of the spin chain with longrange elliptic interactions introduced by Inozemtsev. Our analysis relies on some wellestablished conjectures characterizing the chaotic vs. integrable behavior of a quantum system, formulated in terms of statistical properties of its spectrum. More precisely, we study the distribution of consecutive levels of the (unfolded) spectrum, the power spectrum of the spectral fluctuations, the average degeneracy, and the equivalence to a classical vertex model. Our results are consistent with the general consensus that this model is integrable, and that it is...

Finkel Morgenstern, Federico; González López, Artemio
We solve in closed form the simplest (su(1 vertical bar 1)) supersymmetric version of Inozemtsev's elliptic spin chain, as well as its infinite (hyperbolic) counterpart. The solution relies on the equivalence of these models to a system of free spinless fermions and on the exact computation of the Fourier transform of the resulting elliptic hopping amplitude. We also compute the thermodynamic functions of the finite (elliptic) chain and their low temperature limit and show that the energy levels become normally distributed in the thermodynamic limit. Our results indicate that at low temperatures the su(1 vertical bar 1) elliptic chain behaves...

Botelho, G.; Pellegrino, Daniel; Santos, J; Seoane Sepúlveda, Juan Benigno
In this paper we prove a general version of the extrapolation theorem for absolutely summing nonlinear operators. It is explicitly shown that this result encompasses the previous old and recent, linear and nonlinear extrapolation theorems as particular cases. One of the steps of the proof provides another nonlinear extrapolation theorem of independent interest.

Ansemil, José María M.; Ponte, Socorro; LópezSalazar Codes, Jerónimo
This paper is devoted to studying the space A(U) of all analytic functions on an open subset U of ℝℕ or ℂℕ. It is proved that if U satisfies a weak condition (that will be called the 0property), then every f ϵ A(U) depends only on afinite number of variables. Several topologies on A(U) are then studied: the compactopen topology, the Tδ topology (already known in spaces of holomorphic functions) and a new one, defined by the inductive limit of the subspaces of analytic functions which only depend on a finite number of variables.

Ghosh, A.; Basu, A.; Pardo Llorente, Leandro
The most popular hypothesis testing procedure, the likelihood ratio test, is known to be highly nonrobust in many real situations. Basu et al. (2013a) provided an alternative robust procedure of hypothesis testing based on the density power divergence; however, although the robustness properties of the latter test were intuitively argued for by the authors together with extensive empirical substantiation of the same, no theoretical robustness properties were presented in this work. In the present paper we will consider a more general class of tests which form a superfamily of the procedures described by Basu et al. (2013a). This superfamily derives...

Torres Andrés, R.; Gómez Nicola, Ángel
Making a thermal analysis in the context of NLO SU(3) Chiral Perturbation Theory we see that isospin breaking (1B) corrections (both electromagnetic and QCD ones) to quark condensates are of order beta(e(2)) and beta(epsilon) with epsilon the pi(0)  eta mixing angle. However the combination chi(uu)  chi(ud) of flavour breaking susceptibilities, which vanishes in the isospin limit and can be identified essentially with the connected susceptibility, has an order beta(1) contribution enhanced with T because of the pi 0  eta mixing. Finally we present a thermal sum rule that relates quark condensate ratios and the light scalar susceptibility...

Cobos, Fernando; Segurado, Alba
We work with logarithmic interpolation methods (A0,A1)θ,q,A where θ=0 or 1. On the contrary to the case 0<θ<1, we show that their description in terms of the Jfunctional changes depending on the relationship between q and A, and that there is no description in a certain range. Then we use these J descriptions to investigate the behavior of compact operators and weakly compact operators under logarithmic interpolation methods. In particular, we extend a recent compactness result of Edmunds and Opic for operators between Lpspaces over finite measure spaces to σ finite measure spaces. We also determine the dual of (A0,A1)θ,q,A...

Gómez Nicola, Ángel; Torres Andrés, R.
We analyze quark condensates and chiral (scalar) susceptibilities including isospinbreaking effects at finite temperature T. These include m(u) not equal m(d) contributions as well as electromagnetic (e not equal 0) corrections, both treated in a consistent chiral Lagrangian framework to leading order in SU(2) and SU(3) chiral perturbation theory, so that our predictions are modelindependent. The chiral restoration temperature extracted from <(q) over barq > = <(u) over baru + (d) over bard > is almost unaffected, while the isospinbreaking order parameter <(u) over baru  (d) over bard > grows with T for the threeflavor case SU(3). We derive...

Garay Elizondo, Luis Javier; Mena Marugán, Guillermo A.
The Immirzi ambiguity arises in loop quantum gravity when geometric operators are represented in terms of different connections that are related by means of an extended Wick transform. We analyze the action of this transform in gravity coupled with matter fields and discuss its analogy with the Wick rotation on which the Thiemann transform between Euclidean and Lorentzian gravity is based. In addition, we prove that the effect of this extended Wick transform is equivalent to a constant scale transformation as far as the symplectic structure and kinematical constraints are concerned. This equivalence is broken in the dynamical evolution. Our...

Torres Andrés, Ricardo

Fraguela, Andrés; Infante del Río, Juan Antonio; Ivorra, Benjamin; Ramos del Olmo, Ángel Manuel; Rey Cabezas, Jose María; Smith, Nadia A. S

Fraguela, Andrés; Infante del Río, Juan Antonio; Ramos del Olmo, Ángel Manuel; Rey Cabezas, Jose María