Search

Motivated by a recent paper by the RBC–UKQCD Collaboration, which observes large violations of the naïve factorization hypothesis in K → π π decays, we study in this paper the accuracy of the Vacuum Insertion Approximation (VIA) for the matrix elements of the complete basis of four-fermion Δ F = 2 operators. We perform a comparison between the matrix elements in QCD, evaluated on the lattice, and the VIA predictions. We also investigate the dependence on the external meson masses by computing matrix elements for K , D s , B s and static mesons. In commonly used renormalization schemes, we find large violations of the VIA in particular for one of the two relevant Wick contractions in the kaon sector. These deviations, however, decrease significantly as the meson mass increases and the VIA predictions turn out to be rather well verified for B -meson matrix elements and, even better, in the infinite mass limit. [ABSTRACT FROM AUTHOR]

We present the calculation of the short-distance power corrections to the CP-violation parameter εK coming from dimension-8 operators in the ∆S = 2 effective Hamiltonian. A first estimate of this contribution, obtained for large-Nc and in the chiral limit, was provided in ref. [1]. Here we evaluate and include the O m K 2 / m c 2 and O Λ QCD 2 / m c 2 contributions that, a priori, could induce O (1) corrections to previous estimates, as mK is numerically of order ΛQCD. Our computation shows that there are several dimension-8 operators besides the one considered before. Their effect on εK, however, accidentally cancels out to a large extent, leaving the final correction at the level of 1%. [ABSTRACT FROM AUTHOR]

Abstract: We present a new technique to extract information on the unitarity triangle from the study of Dalitz plot. Using isospin symmetry and the possibility to access the decay amplitudes from Dalitz analyses, we propose a new strategy to extract the weak phase γ from . [Copyright &y& Elsevier]

HEPfit is a flexible open-source tool which, given the Standard Model or any of its extensions, allows to (i) fit the model parameters to a given set of experimental observables; (ii) obtain predictions for observables. HEPfit can be used either in Monte Carlo mode, to perform a Bayesian Markov Chain Monte Carlo analysis of a given model, or as a library, to obtain predictions of observables for a given point in the parameter space of the model, allowing HEPfit to be used in any statistical framework. In the present version, around a thousand observables have been implemented in the Standard Model and in several new physics scenarios. In this paper, we describe the general structure of the code as well as models and observables implemented in the current release. [ABSTRACT FROM AUTHOR]

The halobacterium Haloferax mediterranei was used to study the production of two types of biopolymers: The biopolyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was accumulated as intracellular granules, whereas an extracelluar polysaccharide was excreted in parallel to biopolyester synthesis. After production, microbial re-use and degradation of these polymers under different conditions were investigated to assess the requirements for handling the product-rich fermentation broth prior to the downstream processing for product recovery. Degradation kinetics of the polymers and the impact of different storage conditions on molar mass of PHBV were studied. It turned out that the biotechnological fermentation process can be run without any sterility precautions. No major product losses were observed without pasteurization of fermentation broth after the stop of fermentation. In addition, neither PHBV nor EPS are re-utilized by the cells for biomass formation even if the culture is maintained under conditions of carbon starvation for an extended time. [ABSTRACT FROM AUTHOR]

Abstract: The recently measured branching ratio allows to test the Standard Model by probing virtual effects of new heavy particles, such as a charged Higgs boson. The accuracy of the test is currently limited by the experimental error on and by the uncertainty on the parameters and . The redundancy of the Unitarity Triangle fit allows to reduce the error on these parameters and thus to perform a more precise test of the Standard Model. Using the current experimental inputs, we obtain , to be compared with . The Standard Model prediction can be modified by New Physics effects in the decay amplitude as well as in the Unitarity Triangle fit. We discuss how to disentangle the two possible contributions in the case of minimal flavour violation at large and generic loop-mediated New Physics. We also consider two specific models with minimal flavour violation: the Type-II Two Higgs Doublet Model and the Minimal Supersymmetric Standard Model. [Copyright &y& Elsevier]

Abstract: We propose a method to quantify the Standard Model uncertainty in decays using the experimental data, assuming that power counting provides a reasonable estimate of the subleading terms in the expansion. Using this method, we show that present data are compatible with the Standard Model. We analyze the pattern of subleading terms required to reproduce the data and argue that anomalously large subleading terms are not needed. Finally, we find that is fairly insensitive to hadronic uncertainties and obtain the Standard Model estimate . [Copyright &y& Elsevier]

The present report documents the results of Working Group 2: B, D and K decays, of the workshop on Flavor in the Era of the LHC, held at CERN from November 2005 through March 2007. With the advent of the LHC, we will be able to probe New Physics (NP) up to energy scales almost one order of magnitude larger than it has been possible with present accelerator facilities. While direct detection of new particles will be the main avenue to establish the presence of NP at the LHC, indirect searches will provide precious complementary information, since most probably it will not be possible to measure the full spectrum of new particles and their couplings through direct production. In particular, precision measurements and computations in the realm of flavor physics are expected to play a key role in constraining the unknown parameters of the Lagrangian of any NP model emerging from direct searches at the LHC. The aim of Working Group 2 was twofold: on the one hand, to provide a coherent up-to-date picture of the status of flavor physics before the start of the LHC; on the other hand, to initiate activities on the path towards integrating information on NP from high-pT and flavor data. This report is organized as follows: in Sect. 1, we give an overview of NP models, focusing on a few examples that have been discussed in some detail during the workshop, with a short description of the available computational tools for flavor observables in NP models. Section 2 contains a concise discussion of the main theoretical problem in flavor physics: the evaluation of the relevant hadronic matrix elements for weak decays. Section 3 contains a detailed discussion of NP effects in a set of flavor observables that we identified as “benchmark channels” for NP searches. The experimental prospects for flavor physics at future facilities are discussed in Sect. 4. Finally, Sect. 5 contains some assessments on the work done at the workshop and the prospects for future developments. [ABSTRACT FROM AUTHOR]

Abstract: Combining the recent experimental evidence of mixing, we extract model-independent information on the mixing amplitude and on its CP-violating phase. Using this information, we present new constraints on the flavour structure of up-type squark mass matrices in supersymmetric extensions of the Standard Model. [Copyright &y& Elsevier]

Abstract: We systematically analyze the correlations between the various leptonic and hadronic flavor violating processes arising in SUSY Grand Unified Theories. Using the GUT-symmetric relations between the soft SUSY breaking parameters, we assess the impact of hadronic and leptonic flavor observables on the SUSY sources of flavor violation. [Copyright &y& Elsevier]

We present a next-to-leading order determination of the gluino-mediated SUSY contributions to Bd–Bd mixing and to the CP asymmetry aJ/ψKs in the framework of the mass-insertion approximation. Using hadronic matrix elements recently computed on the lattice, we obtain improved constraints on the squark-mass splittings. [Copyright &y& Elsevier]