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Title: {lambda}NN and {sigma}NN systems at threshold

Abstract

We calculate the hypertriton binding energy and the {lambda}d and {sigma}d scattering lengths using baryon-baryon interactions obtained from a chiral constituent quark model. We study consistently the {lambda}NN and {sigma}NN systems by analyzing the effect of the {sigma}{r_reversible}{lambda} conversion. Our interactions correctly predict the hypertriton binding energy. The (I,J)=(0,3/2) {lambda}NN channel is also attractive and it might have a bound state. From the condition of nonexistence of a (0,3/2) {lambda}NN bound state, an upper limit for the spin-triplet {lambda}N scattering length is obtained. We also present results for the elastic and inelastic {sigma}N and {lambda}N cross sections. The consistent description of the {sigma}N scattering cross sections imposes a lower limit for the corresponding spin-triplet scattering lengths. In the {sigma}NN system the only attractive channels are (I,J)=(1,1/2) and (0,1/2), the (1,1/2) state being the most attractive one.

Authors:
 [1];  [2];  [3];  [4]
  1. Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, Edificio 9, 07738 Mexico D.F. (Mexico)
  2. (Spain)
  3. Departamento de Fisica Teorica e IFIC, Universidad de Valencia-CSIC, E-46100 Burjassot, Valencia (Spain)
  4. Departamento de Fisica Fundamental, Universidad de Salamanca, E-37008 Salamanca (Spain)
Publication Date:
OSTI Identifier:
20995111
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevC.75.034002; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BINDING ENERGY; BOUND STATE; CHIRAL SYMMETRY; CHIRALITY; CROSS SECTIONS; DEUTERONS; HYPERNUCLEI; HYPERONS; NUCLEAR FORCES; NUCLEON-HYPERON INTERACTIONS; QUARK MODEL; SCATTERING; SCATTERING LENGTHS; SPIN; TRIPLETS; TRITONS

Citation Formats

Garcilazo, H., Departamento de Fisica Fundamental, Universidad de Salamanca, E-37008 Salamanca, Fernandez-Carames, T., and Valcarce, A.. {lambda}NN and {sigma}NN systems at threshold. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.034002.
Garcilazo, H., Departamento de Fisica Fundamental, Universidad de Salamanca, E-37008 Salamanca, Fernandez-Carames, T., & Valcarce, A.. {lambda}NN and {sigma}NN systems at threshold. United States. doi:10.1103/PHYSREVC.75.034002.
Garcilazo, H., Departamento de Fisica Fundamental, Universidad de Salamanca, E-37008 Salamanca, Fernandez-Carames, T., and Valcarce, A.. Thu . "{lambda}NN and {sigma}NN systems at threshold". United States. doi:10.1103/PHYSREVC.75.034002.
@article{osti_20995111,
title = {{lambda}NN and {sigma}NN systems at threshold},
author = {Garcilazo, H. and Departamento de Fisica Fundamental, Universidad de Salamanca, E-37008 Salamanca and Fernandez-Carames, T. and Valcarce, A.},
abstractNote = {We calculate the hypertriton binding energy and the {lambda}d and {sigma}d scattering lengths using baryon-baryon interactions obtained from a chiral constituent quark model. We study consistently the {lambda}NN and {sigma}NN systems by analyzing the effect of the {sigma}{r_reversible}{lambda} conversion. Our interactions correctly predict the hypertriton binding energy. The (I,J)=(0,3/2) {lambda}NN channel is also attractive and it might have a bound state. From the condition of nonexistence of a (0,3/2) {lambda}NN bound state, an upper limit for the spin-triplet {lambda}N scattering length is obtained. We also present results for the elastic and inelastic {sigma}N and {lambda}N cross sections. The consistent description of the {sigma}N scattering cross sections imposes a lower limit for the corresponding spin-triplet scattering lengths. In the {sigma}NN system the only attractive channels are (I,J)=(1,1/2) and (0,1/2), the (1,1/2) state being the most attractive one.},
doi = {10.1103/PHYSREVC.75.034002},
journal = {Physical Review. C, Nuclear Physics},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • Using the two-body interactions obtained from a chiral constituent quark model, we study all {lambda}NN and {sigma}NN states with I=0,1,2 and J=1/2,3/2 at threshold, taking into account all three-body configurations with S and D wave components. We constrain further the limits for the {lambda}N spin-triplet scattering length a{sub 1/2,1}. Using the hypertriton binding energy, we find a narrow interval for the possible values of the {lambda}N spin-singlet scattering length a{sub 1/2,0}. We find that the {sigma}NN system has a quasibound state in the (I,J)=(1,1/2) channel very near threshold with a width of about 2.1 MeV.
  • An analysis of 6 GeV/c data for ten different charge channels belonging to the reactions NN yields ( SIGMA K)N and NN yields ( LAMBDA K)N is made in terms of the one-pion-exchange model and the Deck model. Different charge channels are combined in such a way that interferences between isoscalar and isovector exchanges are eliminated. The results of earlier isospin analyses are used to fix the relative proportions of these exchanges for any particular charge channel combination. The model analysis gives a satisfactory semi-quantitative explanation of the data, and in particular of the longitudinal phase space distributions upon whichmore » the earlier isospin analyses were based. (auth)« less
  • The overbinding problem of {sub {lambda}}{sup 5}He is solved by introducing a concept of coherent {lambda}-{sigma} coupling which is equivalent to a {lambda}NN three-body force. This three-body force is coherently enhanced in the 0{sup +} states of {sub {lambda}}{sup 4}H and {sub {lambda}}{sup 4}He. The 0{sup +}-1{sup +} splitting in these hypernuclei is mainly due to coherent {lambda}-{sigma} coupling and partly due to the {lambda}N spin-spin interaction. A {lambda}NN three-body potential is derived from the coupled-channel treatment. The origin of the repulsive and attractive nature of the three-body force is discussed. Coherent {lambda}-{sigma} coupling becomes more important in neutron-rich hypernucleimore » and especially in neutron-star matter at high densities. The possible existence of ''hyperheavy hydrogen'', {sub {lambda}}{sup 6}H, is suggested.« less
  • We report on precision measurements of the cross sections for the reactions {bar p}p{yields}{bar {Lambda}}{Lambda}, {bar p}p{yields}{bar {Lambda}}{Sigma}{sup 0}, and {bar p}p{yields}{bar {Sigma}}{sup 0}{Lambda} in the region below 5 MeV excess kinetic energy above reaction threshold. For the {bar p}p{yields}{bar {Lambda}}{Lambda} measurement, the data represent a third and definitive scan through the threshold region by this experiment. Improvements in the detector system and analysis techniques, coupled with greatly increased statistics, have negated the question of the existence of a near-threshold resonance as had been indicated in our earlier, lower-statistics studies. The high statistics permit the first extraction of the polarizationmore » information at these low energies. We also report the first measurement of the cross section for the complementary reactions {bar p}p{yields}{bar {Lambda}}{Sigma}{sup 0}+c.c. at excess energies up to 2.5 MeV. This allows a comparison of the onset of {bar {Lambda}}{Lambda} production to that of {bar {Lambda}}{Sigma}{sup 0} and {bar {Sigma}}{sup 0}{Lambda}. The data show no evidence for near-threshold resonance structures in either reaction channel. Further, the {bar p}p{yields}{bar {Lambda}}{Sigma}{sup 0}+c.c. reactions exhibit a larger P-wave fraction close to threshold compared to {bar p}p{yields}{bar {Lambda}}{Lambda}.« less