Related papers: Weak Chiral Lagrangian and $pi^+$ Emission in ${}^…
We re-examine the puzzling $\pi^+$ emission from the weak decay of $^4_\Lambda$He and propose an explanation in terms of a three-body decay of the virtual $\Sigma^+$. Such a resolution of the $\pi^+$ decay puzzle is consistent with the…
We take an approach to the $\Lambda$ nonmesonic weak decay in nuclei based on the exchange of mesons under the guidelines of chiral Lagrangians. The one pion and one kaon exchange are considered, together with the exchange of two pions,…
Low energy $\pi^+$ emission in hypernuclear weak decays is studied in the soft pion limit. It is found that the $\pi^+$ decay amplitude is dominated by the $\Delta I=3/2$ part of nonmesonic weak decays according to the soft pion theorem.…
A recently introduced relativistic nuclear energy density functional, constrained by features of low-energy QCD, is extended to describe the structure of hypernuclei. The density-dependent mean field and the spin-orbit potential of a…
We update our previous results for the nonmesonic decay of $^{12}_\Lambda$C and $^5_\Lambda$He. We pay special attention to the role played by Final State Intreractions on the decay observables. We follow a One-Meson-Exchange model which…
We investigate theoretically production cross sections of the $J^\pi=$ 0$^+$ ground state of a $^4_\Lambda$He hypernucleus in the $^4$He($\pi$,~$K$) reaction with a distorted-wave impulse approximation using the optimal Fermi-averaged $\pi…
By means of a coupled channel non-perturbative 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…
Nonmesonic decays of $\Lambda$ in nuclear medium and light hypernuclei are studied by using the $\Lambda N \to NN$ weak transition potential derived from the meson exchange mechanism and the direct quark mechanism. The long range part of…
Decays of $\Lambda$ in nuclei, nonmesonic mode, are studied by using the $\Lambda N \to NN$ weak transition potential derived from the meson exchange mechanism and the direct quark mechanism. The decay rates are calculated both for the…
The complete renormalization of the weak Lagrangian to chiral order q^2 in heavy baryon chiral perturbation theory is performed using heat kernel techniques. The results are compared with divergences appearing in the calculation of Feynman…
We derive the low-energy electroweak effective lagrangian for the case of additional heavy, unmixed, sequential fermions. Present data still allow for the presence of a new quark and/or lepton doublet with masses greater than $M_Z/2$,…
The general character of 4-quark (mesonic) and strange 6-quark (baryonic) quark systems is very briefly reviewed a la Jaffe, i.e. in the MIT bag, and so far still possibly viable candidates are indicated. Concentration is on S=-2 systems.…
We include the leading charge symmetry breaking contributions into the hyperon-nucleon interactions derived within chiral effective field theory up to next-to-leading order. Two low energy constants are determined using the experimentally…
In this Letter, the first evidence of the $^4_{\bar{\Lambda}}\overline{\rm He}$ antihypernucleus is presented, along with the first measurement at the LHC of the production of (anti)hypernuclei with mass number $A=4$, specifically…
If the SM Higgs boson does not exist, electroweak symmetry breaking may be realized via a strong interaction with a typical scale Lambda > 1 TeV. Resonances from the strong sector may help to unitarize WW scattering, which becomes strong in…
We reanalyse the recent version of the chiral model of weak radiative hyperon decays, proposed by Borasoy and Holstein. It is shown that predictions of the analysed model are significantly changed when one accepts the usual classification…
We present a nonrelativistic transition potential for the weak strangeness-changing reaction $\Lambda N \to NN$. The potential is based on a one meson exchange model (OME), where, in addition to the long-ranged pion, the exchange of the…
We examine the meson-baryon interaction in the strangeness S=-1 sector using an effective chiral Lagrangian. Potentials are derived from this Lagrangian and used in a coupled-channel calculation of the low energy observables. The potentials…
The spontaneous breakdown of the chiral symmetry of the QCD Lagrangian ensures that $\pi\pi$ interactions are weak at low energies. How weak depends on the nature of explicit symmetry breaking. Measurements of $K_{e4}$ decays at DA$\Phi$NE…
We study the productions of $\Lambda$-hypernuclei $^3_{\Lambda}$H, $^4_{\Lambda}$H and $^4_{\Lambda}$He in the coalescence mechanism in Au-Au collisions at $\sqrt{s_{NN}}=3$ GeV. Considering the abundance and great importance of baryons and…