4,863 research outputs found
Coupling vector and pseudoscalar mesons to study baryon resonances
A study of meson-baryon systems with total strangeness -1 is made within a
framework based on the chiral and hidden local symmetries. These systems
consist of octet baryons, pseudoscalar and vector mesons. The pseudoscalar
meson-baryon (PB) dynamics has been earlier found determinant for the existence
of some strangeness -1 resonances, for example, ,
, etc. The motivation of the present work is to study the effect
of coupling the closed vector meson-baryon (VB) channels to these resonances.
To do this, we obtain the and
amplitudes from the t-channel diagrams and the
amplitudes are calculated using the Kroll-Ruddermann term where, considering
the vector meson dominance phenomena, the photon is replaced by a vector meson.
The calculations done within this formalism reveal a very strong coupling of
the VB channels to the and . In the isospin 1
case, we find an evidence for a double pole structure of the
which, like the isospin 0 resonances, is also found to couple strongly to the
VB channels. The strong coupling of these low-lying resonances to the VB
channels can have important implications on certain reactions producing them.Comment: Minor typos corrected (in Eq.(22) and axis-labels of some figures
Glow discharge mixture of Ar/He
Glow discharge mixture of Ar/He at a pressure of 266.66 Pa is experimentally investigated by opticalemission spectroscopy and double Langmuir probe at various mixture compositions. The species observedwere He I and Ar I. The electron temperature was found to be less than 10 eV, and the ion densityin the order of 1010 cm-3
Radiative corrections to all charge assignments of heavy quark baryon semileptonic decays
In semileptonic decays of spin-1/2 baryons containing heavy quarks up to six
charge assignments for the baryons and lepton are possible. We show that the
radiative corrections to four of these possibilities can be directly obtained
from the final results of the two possibilities previously studied. There is no
need to recalculate integrals over virtual or real photon momentum or any
traces.Comment: 15 pages, 2 figures, RevTex. Extended discussion. Final version to
appear in Physical Review
Negative parity and resonances coupled to pseudoscalar and vector mesons
An exploration of the dynamically generated and resonances
has been made in the vector meson-baryon (VB) systems coupled to pseudoscalar
meson-baryon (PB) channels. The VB interactions are obtained from the
Lagrangians written within the hidden local symmetry which, in addition to
Yukawa-type vector-baryon-baryon (VBB) vertices, naturally gives rise to a
contact interaction. Using the VBB vertices, we calculate the -, - and
-channel diagrams considering the octet baryon exchange in the latter two
cases. For the PB channels we rely on the the Weingberg-Tomozawa interactions
and calculate the PB VB transition amplitudes extending the
Kroll-Ruderman theorem by replacing the photon by the vector mesons. In
addition to the low-lying , found in previous
works, we find resonances which coincide well with: ,
, , and predict
three 's with and masses: MeV, MeV, MeV together with a broad with mass
1430 MeV. We find that most of these next-to-low-lying states couple
weakly with the pseudoscalar mesons, which implies that it is important to
study the reactions with VB final states in order to obtain a reliable
information on the properties of such resonances
Osmotic and activity coefficients of aqueous solutions of the anesthetic drugs lidocaine-HCl and procaine-HCl at 298.15 K
Osmotic and activity coefficients were measured for aqueous solutions of Lidocaine-HCl and Procaine-HCl using the isopiestic method at 298.15 K. The results were fitted to the Pitzer equation and the parameters were calculated. A good correlation with the Pitzer model was found. The osmotic coefficients thus obtained were analyzed by comparing them with the Debye-HĂŒckel limiting law. The results are discussed in terms of ion-solvent and ion-ion interactions.Colegio de FarmacĂ©uticos de la Provincia de Buenos Aire
- âŠ