Dispersive effects from strongππ rescattering in the final state interaction (FSI) of weak K → ππ decays are revisited with the goal to have a global view on their relative importance for the I = 1/2 rule and the ratio ε′/ε in the standard model (SM). We point out that this goal cannot be reached within a pure effective (meson) field approach like chiral perturbation theory in which the dominan...

We analyze rare kaon decays in models in which the dominant new effect is an enhanced s̄dZ vertex Zds. We point out that in spite of large theoretical uncertainties the CP-violating ratio ε /ε provides at present the strongest constraint on ImZds. Assuming 1.5 · 10−3 ≤ ε/ε ≤ 3 · 10−3 and Standard Model values for the CKM parameters we obtain the bounds BR(KL → π0νν̄) ≤ 3.9 · 10−10 and BR(KL → πee...

This paper analyzes to what extent it is possible to efficiently reduce the number of clauses in NP-hard satisfiability problems, without changing the answer. Upper and lower bounds are established using the concept of kernelization. Existing results show that if NP 6⊆ coNP/poly, no efficient preprocessing algorithm can reduce n-variable instances of cnf-sat with d literals per clause, to equiv...

Within a financial model with linear price impact, we study the problem of hedging a covered European option under gamma constraint. Using stochastic target and partial differential equation smoothing techniques, we prove that the super-replication price is the viscosity solution of a fully non-linear parabolic equation. As a by-product, we show how ε-optimal strategies can be constructed. Fina...

Lattice calculations of matrix elements relevant for kaon decays, and in particular for ε/ε, are reviewed. The rôle of the strange quark mass is also discussed. A comparison with other non-perturbative approaches used to compute kaon decay amplitudes is made. † Presented by G. Martinelli.

The present theoretical status of the parameter for direct CP violation ε/ε in the Standard Model is reviewed and compared with most recent experimental measurements of the same quantity. After collecting the basic expressions for ε/ε, the situation of hadronic matrix element calculations is summarised. The matrix elements constitute the dominant source of uncertainty for theoretical determinat...

In this paper, we study the theoretical properties of a class of iteratively re-weighted least squares (IRLS) algorithms for sparse signal recovery in the presence of noise. We demonstrate a one-toone correspondence between this class of algorithms and a class of Expectation-Maximization (EM) algorithms for constrained maximum likelihood estimation under a Gaussian scale mixture (GSM) distribut...