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Title: Positive and negative-parity flavor-octet baryons in coupled QCD sum rules

Abstract

We apply the method of the QCD sum rule, in which positive- and negative-parity baryons couple with each other, to the flavor-octet hyperons and investigate the parity splittings. We also reexamine the nucleon in the method, which was studied in our previous paper, by carefully choosing the Borel weight. Both in the nucleon and hyperon channels the obtained sum rules turn out to have a very good Borel stability and also have a Borel window, an energy region in which the OPE converges and the pole contribution dominates over the continuum contribution. The predicted masses of the positive- and negative-parity baryons reproduce the experimental ones fairly well in the {lambda} and {sigma} channels, if we assign the {lambda}(1670) and the {sigma}(1620) to the parity partners of the {lambda} and the {sigma}, respectively. This implies that the {lambda}(1405) is not the parity partner of the {lambda} and may be a flavor-singlet or exotic state. In the {xi} channel, the sum rule predicts the mass of the negative-parity state to be about 1.8 GeV, which leads to two possibilities; one is that the observed state with the closest mass, {xi}(1690), is the parity partner and the other is that the parity partnermore » is not yet found but exists around 1.8 GeV.« less

Authors:
; ; ;  [1];  [2];  [2];  [2]
  1. Kokugakuin University, Higashi, Shibuya, Tokyo 150-8440 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
21010986
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevD.75.034010; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; BARYON OCTETS; FLAVOR MODEL; GEV RANGE; LAMBDA-1405 BARYONS; LAMBDA-1670 BARYONS; NUCLEONS; PARITY; QUANTUM CHROMODYNAMICS; SIGMA BARYONS; SUM RULES; XI-1690 BARYONS

Citation Formats

Kondo, Yoshihiko, Morimatsu, Osamu, Nishikawa, Tetsuo, Kanada-En'yo, Yoshiko, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, 1-1, Ooho, Tsukuba, Ibaraki, 305-0801, Department of Physics, Tokyo Institute of Technology, 2-12-1, Oh-Okayama, Meguro, Tokyo 152-8551, and Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502. Positive and negative-parity flavor-octet baryons in coupled QCD sum rules. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.034010.
Kondo, Yoshihiko, Morimatsu, Osamu, Nishikawa, Tetsuo, Kanada-En'yo, Yoshiko, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, 1-1, Ooho, Tsukuba, Ibaraki, 305-0801, Department of Physics, Tokyo Institute of Technology, 2-12-1, Oh-Okayama, Meguro, Tokyo 152-8551, & Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502. Positive and negative-parity flavor-octet baryons in coupled QCD sum rules. United States. doi:10.1103/PHYSREVD.75.034010.
Kondo, Yoshihiko, Morimatsu, Osamu, Nishikawa, Tetsuo, Kanada-En'yo, Yoshiko, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, 1-1, Ooho, Tsukuba, Ibaraki, 305-0801, Department of Physics, Tokyo Institute of Technology, 2-12-1, Oh-Okayama, Meguro, Tokyo 152-8551, and Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502. Thu . "Positive and negative-parity flavor-octet baryons in coupled QCD sum rules". United States. doi:10.1103/PHYSREVD.75.034010.
@article{osti_21010986,
title = {Positive and negative-parity flavor-octet baryons in coupled QCD sum rules},
author = {Kondo, Yoshihiko and Morimatsu, Osamu and Nishikawa, Tetsuo and Kanada-En'yo, Yoshiko and Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, 1-1, Ooho, Tsukuba, Ibaraki, 305-0801 and Department of Physics, Tokyo Institute of Technology, 2-12-1, Oh-Okayama, Meguro, Tokyo 152-8551 and Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502},
abstractNote = {We apply the method of the QCD sum rule, in which positive- and negative-parity baryons couple with each other, to the flavor-octet hyperons and investigate the parity splittings. We also reexamine the nucleon in the method, which was studied in our previous paper, by carefully choosing the Borel weight. Both in the nucleon and hyperon channels the obtained sum rules turn out to have a very good Borel stability and also have a Borel window, an energy region in which the OPE converges and the pole contribution dominates over the continuum contribution. The predicted masses of the positive- and negative-parity baryons reproduce the experimental ones fairly well in the {lambda} and {sigma} channels, if we assign the {lambda}(1670) and the {sigma}(1620) to the parity partners of the {lambda} and the {sigma}, respectively. This implies that the {lambda}(1405) is not the parity partner of the {lambda} and may be a flavor-singlet or exotic state. In the {xi} channel, the sum rule predicts the mass of the negative-parity state to be about 1.8 GeV, which leads to two possibilities; one is that the observed state with the closest mass, {xi}(1690), is the parity partner and the other is that the parity partner is not yet found but exists around 1.8 GeV.},
doi = {10.1103/PHYSREVD.75.034010},
journal = {Physical Review. D, Particles Fields},
number = 3,
volume = 75,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}