Kℓ4K_{\ell 4} Form-Factors and π\pi-π\pi Scattering

The $F$ and $G$ form-factors of $K_{\ell4}$ and the quark condensates are calculated to ${\cal O}(p^6)$ in Chiral Perturbation Theory (CHPT). Full formulas are presented as much as possible. A full refit of most of the ${\cal O}(p^4)$ CHPT parameters is done with a discussion of all inputs and underlying assumptions. We discuss the consequences for the vacuum expectation values, decay constants, pseudoscalar masses and $\pi$-$\pi$ scattering.Comment: 51 page

S-wave Meson-Meson Scattering from Unitarized U(3) Chiral Lagrangians

An investigation of the s-wave channels in meson-meson scattering is performed within a U(3) chiral unitary approach. Our calculations are based on a chiral effective Lagrangian which includes the eta' as an explicit degree of freedom and incorporates important features of the underlying QCD Lagrangian such as the axial U(1) anomaly. We employ a coupled channel Bethe-Salpeter equation to generate poles from composed states of two pseudoscalar mesons. Our results are compared with experimental phase shifts up to 1.5 GeV and effects of the eta' within this scheme are discussed.Comment: 18 pages, 6 figure

Chiral symmetry breaking and effective lagrangians for softly broken supersymmetric QCD

We study supersymmetric QCD with N_f<N_c in the limit of small supersymmetry-breaking masses and smaller quark masses using the weak-coupling Kahler potential. We calculate the full spectrum of this theory, which manifests a chiral symmetry breaking pattern similar to that caused by the strong interactions of the standard model. We derive the chiral effective lagrangian for the pion degrees of freedom, and discuss the behavior in the formal limit of large squark and gluino masses and for large N_c. We show that the resulting scalings of the pion decay constant and pion masses in these limits differ from those expected in ordinary nonsupersymmetric QCD. Although there is no weak coupling expansion with N_f=N_c, we extend our results to this case by constructing a superfield quantum modified constraint in the presence of supersymmetry breaking.Comment: 16 pages, LaTe

Recurrences of ventricular tachycardia after stereotactic arrhythmia radioablation arise outside the treated volume: analysis of the swiss cohort

BACKGROUND AND AIMS Stereotactic arrhythmia radioablation (STAR) has been recently introduced for the management of therapy-refractory ventricular tachycardia (VT). VT recurrences have been reported after STAR but the mechanisms remain largely unknown. We analyzed recurrences in our patients after STAR. METHODS From 09.2017 to 01.2020, 20 patients (68±8y, LVEF 37±15%) suffering from refractory VT were enrolled, 16/20 with a history of at least 1 electrical storm. Before STAR, an invasive electro-anatomical mapping (Carto3) of the VT substrate was performed. A mean dose of 23±2Gy was delivered to the planning target volume (PTV). RESULTS The median ablation volume was 26 ml (range 14-115) and involved the interventricular septum in 75% of patients. During the first 6 months after STAR, VT burden decreased by 92% (median value, from 108 to 10 VT/semester). After a median follow-up of 25 months, 12/20 (60%) developed a recurrence and underwent a redo ablation. VT recurrence was located in proximity of the treated substrate in 9 cases, remote from the PTV in 3 cases and involved a larger substrate over ≥3 LV segments in 2 cases. No recurrences occurred inside the PTV. Voltage measurements showed a significant decrease in both bipolar and unipolar signal amplitude after STAR. CONCLUSION STAR is a new tool available for the treatment of VT, allowing for a significant reduction of VT burden. VT recurrences are common during follow-up, but no recurrences were observed inside the PTV. Local efficacy was supported by a significant decrease in both bipolar and unipolar signal amplitude

Electromagnetic transitions in an effective chiral Lagrangian with the eta-prime and light vector mesons

We consider the chiral Lagrangian with a nonet of Goldstone bosons and a nonet of light vector mesons. The mixing between the pseudoscalar mesons eta and eta-prime is taken into account. A novel counting scheme is suggested that is based on hadrogenesis, which conjectures a mass gap in the meson spectrum of QCD in the limit of a large number of colors. Such a mass gap would justify to consider the vector mesons and the eta-prime meson as light degrees of freedom. The complete leading order Lagrangian is constructed and discussed. As a first application it is tested against electromagnetic transitions of light vector mesons to pseudoscalar mesons. Our parameters are determined by the experimental data on photon decays of the omega, phi and eta-prime meson. In terms of such parameters we predict the corresponding decays into virtual photons with either dielectrons or dimuons in the final state.Comment: 17 pages, extended discussion on mixin

Putative Light Scalar Nonet

We investigate the "family" relationship of a possible scalar nonet composed of the a_0(980), the f_0(980) and the \sigma and \kappa type states found in recent treatments of \pi\pi and \pi K scattering. We work in the effective Lagrangian framework, starting from terms which yield "ideal mixing" according to Okubo's original formulation. It is noted that there is another solution corresponding to dual ideal mixing which agrees with Jaffe's picture of scalars as qq\bar q \bar q states rather than as q\bar q states. At the Lagrangian level there is no difference in the formulation of the two cases (other than the numerical values of the coefficients). In order to agree with experiment, additional mass and coupling terms which break ideal mixing are included. The resulting model turns out to be closer to dual ideal mixing than to conventional ideal mixing; the scalar mixing angle is roughly -17 degrees in a convention where dual ideal mixing is 0 degrees.Comment: 24 pages, 3 figure

2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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