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RESUMEN El 28 de junio de 2019 la UE y el MERCOSUR llegaron a un compromiso para la firma de un Acuerdo de Asociación Comercial. En el ámbito agroalimentario, el Acuerdo de Asociación establece una serie de instrumentos para impulsar el intercambio de productos entre los dos bloques regionales. Entre las medidas negociadas para impulsar el comercio entre las dos regiones está la disminución programada de las tarifas y el uso transparente de las medidas sanitarias y fitosanitarias. Aunque las negociaciones tomaron un plazo muy largo debido, entre otros motivos, al desacuerdo sobre temas como las cuotas de exportación hacia la UE de carne bovina del MERCOSUR y la protección en los países del MERCOSUR de las Indicaciones Geográficas registradas en la UE, el Acuerdo de Asociación resulta ser un logro mayor por abarcar un mercado de casi 780 millones de consumidores. Los beneficios a largo plazo del acuerdo para el sector agroalimentario son todavía dudosos, sin embargo, la asociación comercial entre los dos bloques regionales es vista también como un impulso hacia una mayor integración económica y una diversificación de los procesos productivos de los países del MERCOSUR y para que la UE tome medidas para reformar su política agrícola. RESUMO Em 28 de junho de 2019, a UE e o MERCOSUL chegaram a um Acordo de Princípios para a assinatura de um Acordo de Associação Comercial. No setor agroalimentar, o Acordo de Associação estabelece uma série de instrumentos para promover o intercâmbio de produtos entre os dois blocos regionais. Entre as medidas negociadas para impulsionar o comércio entre as duas regiões está a redução programada de tarifas e o uso transparente de medidas sanitárias e fitossanitárias. Embora as negociações tenham demorado muito, devido, entre outros motivos, a divergências sobre questões como as cotas de exportação para a UE da carne bovina do MERCOSUL e a proteção nos países do MERCOSUL das indicações geográficas registradas na UE, o Acordo a Parceria acaba sendo uma conquista importante para cobrir um mercado de quase 780 milhões de consumidores. Os benefícios de longo prazo do acordo para o setor agroalimentar ainda são duvidosos; no entanto, a associação comercial entre os dois blocos regionais também é vista como um impulso para uma maior integração econômica e diversificação dos processos produtivos dos países do MERCOSUL e para a UE tomar medidas para reformar sua política agrícola. ABSTRACT On 28 June 2019, the EU and the MERCOSUR reached consensus for the signature of a Trade Agreement. In the agro-food sector, the agreement provides a series of instruments aimed at increasing the volumes of exchange between the two regional blocks. Among the tools negotiated to boost bilateral trade is a scheduled reduction of tariffs and the means for the transparent application of the sanitary and phytosanitary measures. Although the negotiations have taken an exceptionally long time, inter alia, for the discordant positions on the quotas of beef imported in the EU from the MERCOSUR and on the protection in the MERCOSUR of the Geographical Indications registered in the EU, the Trade Agreement is considered a major achievement for encompassing a market of almost 780 million of consumers. The long-term benefits of the agreement in the agro-food sector are still unknown, however, the trade association between the two partners should also be seen as a driver towards a greater economic integration and the diversification of the production processes in the MERCOSUR and as an opportunity for the EU to reform its agricultural policy.

We apply Zeilberger summation to derive a closed formula for the wrapping correction to one-impurity states in the [Formula: see text] sector of the β-deformed [Formula: see text] SYM theory at β = 1/2. As an application depending heavily on the result, we compute the large volume expansion of the wrapping correction.

An extension of Nelson’s stochastic mechanics to the relativistic domain is proposed. To each pure state of a spinless relativistic quantum particle corresponds a Markov process t ]ξt, where the random variable ξt represents, at every time t, the space position of the particle in the sense of Newton and Wigner. The process t ]ξt is not a diffusion but the usual Nelson’s theory is restored in the nonrelativistic limit.

We study at strong coupling the scaling function describing the large spin anomalous dimension of twist two operators in ${\cal N}=4$ super Yang-Mills theory. In the spirit of AdS/CFT duality, it is possible to extract it from the string Bethe Ansatz equations in the $\mathfrak{sl}(2)$ sector of the $\ads$ superstring. To this aim, we present a detailed analysis of the Bethe equations by numerical and analytical methods. We recover several short string semiclassical results as a check. In the more difficult case of the long string limit providing the scaling function, we analyze the strong coupling version of the Eden-Staudacher equation, including the Arutyunov-Frolov-Staudacher phase. We prove that it admits a unique solution, at least in perturbation theory, leading to the correct prediction consistent with semiclassical string calculations., Comment: 25 pages, 5 eps figures

We study dynamical supersymmetry breaking and the transition point by non-perturbative lattice techniques in a class of two-dimensional N=1 Wess-Zumino model. The method is based on the calculation of rigorous lower bounds on the ground state energy density in the infinite-lattice limit. Such bounds are useful in the discussion of supersymmetry phase transition. The transition point is determined with this method and then compared with recent results based on large-scale Green Function Monte Carlo simulations with good agreement., 6 pages, 4 figs. Lattice2005 (theory), uses PoS

A new approach to the study of the transition point in a class of two dimensional Wess-Zumino models is presented. The method is based on the calculation of rigorous lower bounds on the ground state energy density in the infinite lattice limit. Such bounds are useful in the discussion of supersymmetry phase transition. The transition point is then determined and compared with recent results based on large-scale Green Function Monte Carlo simulations with good agreement., 4 pages, 1 figure, Talk presented at Quark Confinement and the Hadron Spectrum VI, Villasimius, Sardinia, Italy, September 21-25, 2004

We study the lattice N=1 Wess-Zumino model in two dimensions and we construct a sequence $\rho^{(L)}$ of exact lower bounds on its ground state energy density $\rho$, converging to $\rho$ in the limit $L\to\infty$. The bounds $\rho^{(L)}$ can be computed numerically on a finite lattice with $L$ sites and can be exploited to discuss dynamical symmetry breaking. The transition point is determined and compared with recent results based on large-scale Green Function Monte Carlo simulations with good agreement., Comment: 32 pages, 12 figures

Feynman started the theory of quantum computation by observing that quantum mechanical amplitudes cannot be simulated efficiently on a computer, since path integrals are computationally hard. Path integrals are heuristic tools for Schrödinger's hamiltonians, at least for real time dynamics. On the contrary they have a rigorous mathematical meaning for quantum systems which are worth a finite but no matter how large number of qubits.

We describe an exact Feynman-Kac type formula to represent the dynamics of fermionic lattice systems. In this approach the real time or Euclidean time dynamics is expressed in terms of the stochastic evolution of a collection of Poisson processes. From this formula we derive a family of algorithms for Monte Carlo simulations, parametrized by the jump rates of the Poisson processes.

We present a simple derivation of a Feynman-Kac type formula to study fermionic systems. In this approach the real time or the imaginary time dynamics is expressed in terms of the evolution of a collection of Poisson processes. A computer implementation of this formula leads to a family of algorithms parametrized by the values of the jump rates of the Poisson processes. From these an optimal algorithm can be chosen which coincides with the Green Function Monte Carlo method in the limit when the latter becomes exact., 4 pages, 1 PostScript figure, REVTeX

We study the highest states in the compact rank-1 sectors of the AdS5 X S5 superstring in the framework of the recently proposed light cone Bethe Ansatz equations. In the su(1|1) sector we present strong coupling expansions in the two limits L,lambda -> OO (expanding in power of lambda^{-1/4} with fixed large L) and lambda, L -> OO (expanding in power of 1/L with fixed large lambda) where lambda is the 't Hooft coupling and L is the number of Bethe momenta. The two limits do not commute apart from the leading term which reproduces the result obtained with the Arutyunov-Frolov-Staudacher phase in the lambda, L -> OO limit. In the su(2) sector we perform the strong coupling expansions in the L->OO limit up to O(lambda^{-1/4}), and our result is in agreement with previuos String Bethe Ansatz analysis.

It is demonstrated, via recent global estimates for the heat kernel found by Li and Yau [Acta Matematica 156, 153 (1986)], that the covariance of the mass m free field decays exponentially, at a rate m, with the geodesic distance on any complete, noncompact Riemannian manifold with non‐negative Ricci curvature. The rate of the exponential decay is larger than m on simply connected manifolds with negative sectional curvature.

We extend to “Euclidean” fields on a wide class of Riemannian manifolds two results which have proven to be crucial in the construction of interacting quantum fields in the flat case, namely local regularity properties of the free covariance in two dimensions and Osterwalder-Schrader positivity.

Wilson's lattice approximation allows us to apply classical statistical mechanics ideas to the study of Scalar Quantum Electrodynamics. Our main tools are Griffiths-Kelly-Sherman inequalities, the transfer matrix formalism and exponential bounds. Our main result is the existence of the infinite volume limit for every value of the coupling parameters.

We consider spin systems in two dimensions having the discrete symmetry group Z N . We give a bound on the spontaneous magnetization for such systems which reduces to the classical Mermin-Wager argument as N goes to infinity.

We consider Wilson's lattice approximation to scalar Quantum Electrodynamics. We establish correlation inequalities of Griffiths-Kelly-Sherman type and a rigorous transfer matrix formalism, from which existence and non triviality of the infinite volume limit follow.

Let (M,g) be a static manifold (for notational simplicity of dimension 2) with a metric of Lorentzian signature. Fix a global chart $$ \Sigma :P \in M \to ({x^0},{x^1})\,{\mathbb{R}^2} $$ in which the metric satisfies: $$ \frac{\partial }{{\partial {x^0}}}{g_{{\mu \nu }}} = 0,\,{g_{{10}}} = 0 $$ (1)

As a step towards a rigorous control of the continuum limit for Wilson's gauge theories on the lattice, we study the problem of removing the compactification of field variables. In the specific examples we consider (the plane rotator and the massive vector field) we not only recover the expected Gaussian limit on the lattice, but also give strong results towards the direct recovery of the continuum limit.

We follow a "Euclidean" or, better, a "properly Riemannian" strategy for the construction of quantum fields on curved spacetime. Our work can best be described as a study_of the proposal advanced by J.B.Hartle and S.W.Hawking in their 1976 article "Path integral derivation of black hole radiance" (i), in much the same sense as the Euclidean program for the flat case has been a successful attempt to understand, by a precise mathematical construction, K.Symanzik's Varenna Lectures (2). We are perfectly well aware of the conceptual difficulties of a "Euclidean!' approach to quantum field theory on a gravitational background, such as the lack of a general covariant analysis of the procedure of analytic continuation to "imaginary time" (3) and the related difficulty of getting information back to real time (4). On this reconstruction problem we take the attitude that, before tackling it in all its generality and difficulty, it might be worth to explore it on explicitly constructed, if possible interacting, models. A related objection to the "properly Riemannian approach" is the observatinn that the well established "Euclidean" approach refers to the analytically continued vacuum expectation values of the fields, while on a curved manifold with, in general, a non stationary metric one has neither Poincar~ invariance by which to characterize a vacuum state nor an energy-momentum by whose spectral properties to ensure the possibility of analytic continuation.