RESUMO
We solve for the first time, the Faddeev equations for the bound state problem of the coupled ΛΛN-ΞNN system to study whether or not a hypertriton with strangeness -2 may exist. We make use of the interactions obtained from a chiral quark model describing the low-energy observables of the two-baryon systems with strangeness 0, -1, and -2 and three-baryon systems with strangeness 0 and -1. The ΛΛN system alone is unbound. However, when the full coupling to ΞNN is considered, the strangeness -2 three-baryon system with quantum numbers (I,J(P)) = (1/2,1/2(+)) becomes bound, with a binding energy of about 0.5 MeV. This result is compatible with the nonexistence of a stable (Λ)(3)H with isospin one.
RESUMO
The red-giant branch (RGB) in globular clusters is extended to larger brightness if the degenerate helium core loses too much energy in "dark channels." Based on a large set of archival observations, we provide high-precision photometry for the Galactic globular cluster M5 (NGC 5904), allowing for a detailed comparison between the observed tip of the RGB with predictions based on contemporary stellar evolution theory. In particular, we derive 95% confidence limits of g(ae)<4.3×10(-13) on the axion-electron coupling and µ(ν)<4.5×10(-12)µ(B) (Bohr magneton µ(B)=e/2m(e)) on a neutrino dipole moment, based on a detailed analysis of statistical and systematic uncertainties. The cluster distance is the single largest source of uncertainty and can be improved in the future.
RESUMO
We present a systematic and self-consistent analysis of four-quark charmonium states and applied it to study compact four-quark systems and meson-meson molecules. Our results are robust and should serve to clarify the situation of charmonium spectroscopy above the threshold production of charmed mesons.
RESUMO
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