On the Impact of the Quark Many-body Effects on Exotic Hadrons
ORAL
Abstract
The constituent quark models successfully explain the features of the single hadrons. The hadron interactions are also well-reproduced. For example, the channel dependence of the short-range part of two-baryon interaction corresponds to those given by the Lattice QCD.
In this work, we investigate the exotic hadrons like (q qbar)-(q qbar). The spin-dependent term of the one-gluon exchange force (CMI) has been well investigated and is found to be responsible for giving an attraction to form many of the exotic hadrons.
However, from the study on the two-baryon systems, it is known that the quark many-body effects, such as the quark Pauli-blocking, are more significant.
The effect of hadrons being composed of multiple quarks is incorporated into the present model as a spectroscopic factor (S-factor). This effect can be repulsive (because of the quark Pauli-blocking) or attractive (because of the many-body effect) and has strong channel dependence. The effect appears in the overlapping spacial region between the compact quark configuration and the two-hadron scattering states.
By using a quark-hadron hybrid model that includes both of the above effects, we investigate the Tcc.The Tcc, ubar-dbar-cc I(JP )=0(1+), consists of two components: (A) cc spin-1 ubar-dbar spin-0 and (B) cc spin-0 ubar-dbar spin-1. Because of the symmetry, there is no cc spin-1 ubar-dbar spin-1 component with the isospin 0. For both of the components, the CMI is attractive, but their sizes are different. CMI in (A) is six times more attractive than in (B). On the other hand, the S-factor in (A) is repulsive, while it is attractive in (B). As a result of this cancellation, we found that without the long-range attraction from the pion exchange, the Tcc becomes a virtual state. Also, we found that Tbb is a deeply bound state because the S-factor effect reduces in a compact state.
Such a cancellation can also be seen in other exotic hadrons, such as the Pc or Pcs. Our aim here is a comprehensive understanding of the mechanism to form the exotic hadrons.
In this work, we investigate the exotic hadrons like (q qbar)-(q qbar). The spin-dependent term of the one-gluon exchange force (CMI) has been well investigated and is found to be responsible for giving an attraction to form many of the exotic hadrons.
However, from the study on the two-baryon systems, it is known that the quark many-body effects, such as the quark Pauli-blocking, are more significant.
The effect of hadrons being composed of multiple quarks is incorporated into the present model as a spectroscopic factor (S-factor). This effect can be repulsive (because of the quark Pauli-blocking) or attractive (because of the many-body effect) and has strong channel dependence. The effect appears in the overlapping spacial region between the compact quark configuration and the two-hadron scattering states.
By using a quark-hadron hybrid model that includes both of the above effects, we investigate the Tcc.The Tcc, ubar-dbar-cc I(JP )=0(1+), consists of two components: (A) cc spin-1 ubar-dbar spin-0 and (B) cc spin-0 ubar-dbar spin-1. Because of the symmetry, there is no cc spin-1 ubar-dbar spin-1 component with the isospin 0. For both of the components, the CMI is attractive, but their sizes are different. CMI in (A) is six times more attractive than in (B). On the other hand, the S-factor in (A) is repulsive, while it is attractive in (B). As a result of this cancellation, we found that without the long-range attraction from the pion exchange, the Tcc becomes a virtual state. Also, we found that Tbb is a deeply bound state because the S-factor effect reduces in a compact state.
Such a cancellation can also be seen in other exotic hadrons, such as the Pc or Pcs. Our aim here is a comprehensive understanding of the mechanism to form the exotic hadrons.
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Publication: [1] S. Takeuchi and M. Takizawa, Phys. Lett. B 764, 254 (2017), arXiv:1608.05475 [hep-ph].<br>[2] Y. Yamaguchi, A. Hosaka, S. Takeuchi, and M. Tak- izawa, J. Phys. G 47, 053001 (2020), arXiv:1908.08790 [hep-ph].<br>[3] Yasuhiro Yamaguchi, Hugo Garcia-Tecocoatzi, Alessandro Giachino, Atsushi Hosaka, Elena Santopinto, Sachiko Takeuchi, Makoto Takizawa, Phys.Rev.D 101 (2020) 9, 091502.
Presenters
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Sachiko Takeuchi
Japan College of Social Work
Authors
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Sachiko Takeuchi
Japan College of Social Work
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Makoto Takizawa
Showa Pharmaceutical University
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Yasuhiro Yamaguchi
Nagoya University
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Atsushi Hosaka
RCNP, Osaka University