F. Okiharu - Academia.edu (original) (raw)

Papers by F. Okiharu

Nuclear Physics B - Proceedings Supplements, 2004

AIP Conference Proceedings, 2006

ABSTRACT We study multi-quark (3Q,4Q,5Q) systems in lattice QCD. We perform the detailed studies ... more ABSTRACT We study multi-quark (3Q,4Q,5Q) systems in lattice QCD. We perform the detailed studies of multi-quark potentials in lattice QCD to clarify the inter-quark interaction in multi-quark systems. We find that all the multi-quark potentials are well described by the OGE Coulomb plus multi-Y-type linear potential, i.e., the multi-Y Ansatz. For multi-quark systems, we observe lattice QCD evidences of ``flip-flop'', i.e., flux-tube recombination. These lattice QCD studies give an important bridge between elementary particle physics and nuclear physics. Comment: A talk given at Particles and Nuclei International Conference(PANIC05), Santa Fe, NM, Oct. 24-28, 2005. 3 pages, 6 figures

Few-Body Problems in Physics, 2007

ABSTRACT LADY CATS (LADY Creators of Activities for Teaching Science) is an organization of scien... more ABSTRACT LADY CATS (LADY Creators of Activities for Teaching Science) is an organization of science teachers. Our group includes a lot of female teachers, which is rather unusual in the field of physics. We would like to propose and exhibit beautiful and simple science experiments that can demonstrate the principles of physics to fascinate students’ interest. These experiments are easily made and low‐cost. It is also aimed to catch female and humanities students’ eyes on physics from the view point of female teachers. Furthermore, we believe that these ideas help resolve gender problems and support non‐specialist teachers in primary school.

ABSTRACT We study three subjects on quark confinement in hadrons in SU(3)$_{\rm c}$ lattice QCD. ... more ABSTRACT We study three subjects on quark confinement in hadrons in SU(3)$_{\rm c}$ lattice QCD. From the accurate lattice calculation for more than 300 different patterns of three-quark (3Q) systems, we find that the static 3Q potential is well described by Y-Ansatz, i.e., the Coulomb plus Y-type linear potential. We also study the multi-quark (4Q, 5Q) potentials in lattice QCD, and find that they are well described by the one-gluon-exchange (OGE) Coulomb plus string-theoretical linear potential, which supports the {\it infrared string picture} even for the multi-quarks. The second subject is a lattice-QCD determination of the relevant gluonic momentum component for confinement. The string tension (confining force) is found to be almost unchanged even after cutting off the high-momentum gluon component above 1.5GeV in the Landau gauge. In fact, {\it quark confinement originates from the low-momentum gluon below about 1.5GeV.} Finally, we consider a possible gauge of QCD for the quark potential model, by investigating "instantaneous inter-quark potential" in generalized Landau gauge, which describes a continuous change from the Landau gauge to the Coulomb gauge.

Progress of Theoretical Physics Supplement, 2007

In this write-up, we summarize our recent analysis of radiative decays involving light scalar mes... more In this write-up, we summarize our recent analysis of radiative decays involving light scalar mesons. Our analysis using the vector meson dominance model at tree level indicates that it may be difficult to distinguish qqqq picture and qq picture for the light scalar nonet. Our ...

Physical Review D, 2005

The penta-quark(5Q) baryon is studied in anisotropic quenched lattice QCD with renormalized aniso... more The penta-quark(5Q) baryon is studied in anisotropic quenched lattice QCD with renormalized anisotropy as/at=4 for a high-precision mass measurement. The standard Wilson action at β = 5.75 and the O(a) improved Wilson quark action with κ=0.1210(0.0010)0.1240 are employed on a 12 3 ×96 lattice. Contribution of excited states is suppressed by using a smeared source. We investigate both the positive-and negative-parity 5Q baryons with I = 0 and spin J = 1/2 using a non-NK-type interpolating field. After chiral extrapolation, the lowest positive-parity state is found to have a mass, mΘ = 2.25 GeV, which is much heavier than the experimentally observed Θ + (1540). The lowest negative-parity 5Q appears at mΘ = 1.75 GeV, which is near the s-wave NK threshold. To distinguish spatially-localized 5Q resonances from NK scattering states, we propose a new general method imposing a "Hybrid Boundary Condition (HBC)", where the NK threshold is artificially raised without affecting compact five-quark states. The study using the HBC method shows that the negative-parity state observed on the lattice is not a compact 5Q but an s-wave NK-scattering state.

Nuclear Physics B - Proceedings Supplements, 2005

The penta-quark(5Q) Θ + (1540) is studied in anisotropic lattice QCD with renormalized anisotropy... more The penta-quark(5Q) Θ + (1540) is studied in anisotropic lattice QCD with renormalized anisotropy as/at = 4 for a high-precision measurement. Both the positive and the negative parity 5Q baryons are studied using a non-NK type interpolating field with I = 0 and J = 1/2. After the chiral extrapolation, the lowest positive parity state is found at mΘ ≃ 2.25 GeV, which is too heavy to be identified with Θ + (1540). In the negative parity channel, the lowest energy state is found at mΘ ≃ 1.75 GeV. Although it is rather close to the empirical value, it is considered to be an NK scattering state rather than a localized resonance state.

Nuclear Physics A, 2005

Penta-quark (5Q) baryons are studied using anisotropic lattice QCD for high-precision measurement... more Penta-quark (5Q) baryons are studied using anisotropic lattice QCD for high-precision measurement of temporal correlators. A non-NK-type interpolating field is employed to study the 5Q states with J P = 1/2 ± and I = 0. In J P = 1/2 + channel, the lowest-lying state is found at m 5Q ≃ 2.25 GeV, which is too massive to be identified as the Θ + (1540). In J P = 1/2 − channel, the lowest-lying state is found at m 5Q ≃ 1.75 GeV. To distinguish a compact 5Q resonance state from an NK scattering state, a new method with "hybrid boundary condition (HBC)" is proposed. As a result of the HBC analysis, the observed state in the negative-parity channel turns out to be an NK scattering state.

Nuclear Physics A, 2005

We study the narrow decay width of low-lying penta-quark baryons in the QCD string theory in term... more We study the narrow decay width of low-lying penta-quark baryons in the QCD string theory in terms of gluonic excitations. In the QCD string theory, the penta-quark baryon decays via a gluonic-excited state of a baryon and meson system, where a pair of Y-shaped junction and anti-junction is created. Since lattice QCD shows that the lowest gluonicexcitation energy takes a large value of about 1 GeV, the decay of the penta-quark baryon near the threshold is considered as a quantum tunneling process via a highly-excited state (a gluonic-excited state) in the QCD string theory. This mechanism strongly suppresses the decay and leads to an extremely narrow decay width of the penta-quark system.

The European Physical Journal C, 2004

A gauge field link smearing method developed for calculations with staggered fermions, namely the... more A gauge field link smearing method developed for calculations with staggered fermions, namely the use of unitarized fat7 links, is applied to mesonic and baryonic Wilson loop calculations. This method is found to be very effective for reducing statistical fluctuations for large Wilson loops. Examination of chromo-electric field distributions shows that self-interactions of the static sources are reduced when unitarized fat7 smearing is used but long-distance inter-quark effects are unchanged.

AIP Conference Proceedings, 2006

Anisotropic lattice QCD studies of penta-quarks(5Q) with J P = 1/2 ± and 3/2 ± are presented at t... more Anisotropic lattice QCD studies of penta-quarks(5Q) with J P = 1/2 ± and 3/2 ± are presented at the quenched level together with tetra-quarks(4Q). The standard gauge action at β = 5.75 and O(a) improved quark (clover) action with κ = 0.1410(0.010)0.1440 are employed on the anisotropic lattice with the renormalized anisotropy a s /a t = 4. The "hybrid boundary condition(HBC)" is adopted to discriminate a compact resonance state from scattering states. Only massive 5Q states are found for J P = 1/2 + and 3/2 ± , which cannot be identified as Θ + (1540). A low-lying 5Q state is found for J P = 1/2 − at m 5Q ≃ 1.75 GeV, which however turns out to be an NK scattering state through the HBC analysis. A preliminary result for 4Q states is presented suggesting an existence of a compact 4Q resonance at m 4Q ≃ 1.1 GeV in the idealized SU(4) f chiral limit.

Nuclear Physics B - Proceedings Supplements, 2004

AIP Conference Proceedings, 2006

ABSTRACT We study multi-quark (3Q,4Q,5Q) systems in lattice QCD. We perform the detailed studies ... more ABSTRACT We study multi-quark (3Q,4Q,5Q) systems in lattice QCD. We perform the detailed studies of multi-quark potentials in lattice QCD to clarify the inter-quark interaction in multi-quark systems. We find that all the multi-quark potentials are well described by the OGE Coulomb plus multi-Y-type linear potential, i.e., the multi-Y Ansatz. For multi-quark systems, we observe lattice QCD evidences of ``flip-flop'', i.e., flux-tube recombination. These lattice QCD studies give an important bridge between elementary particle physics and nuclear physics. Comment: A talk given at Particles and Nuclei International Conference(PANIC05), Santa Fe, NM, Oct. 24-28, 2005. 3 pages, 6 figures

Few-Body Problems in Physics, 2007

ABSTRACT LADY CATS (LADY Creators of Activities for Teaching Science) is an organization of scien... more ABSTRACT LADY CATS (LADY Creators of Activities for Teaching Science) is an organization of science teachers. Our group includes a lot of female teachers, which is rather unusual in the field of physics. We would like to propose and exhibit beautiful and simple science experiments that can demonstrate the principles of physics to fascinate students’ interest. These experiments are easily made and low‐cost. It is also aimed to catch female and humanities students’ eyes on physics from the view point of female teachers. Furthermore, we believe that these ideas help resolve gender problems and support non‐specialist teachers in primary school.

ABSTRACT We study three subjects on quark confinement in hadrons in SU(3)$_{\rm c}$ lattice QCD. ... more ABSTRACT We study three subjects on quark confinement in hadrons in SU(3)$_{\rm c}$ lattice QCD. From the accurate lattice calculation for more than 300 different patterns of three-quark (3Q) systems, we find that the static 3Q potential is well described by Y-Ansatz, i.e., the Coulomb plus Y-type linear potential. We also study the multi-quark (4Q, 5Q) potentials in lattice QCD, and find that they are well described by the one-gluon-exchange (OGE) Coulomb plus string-theoretical linear potential, which supports the {\it infrared string picture} even for the multi-quarks. The second subject is a lattice-QCD determination of the relevant gluonic momentum component for confinement. The string tension (confining force) is found to be almost unchanged even after cutting off the high-momentum gluon component above 1.5GeV in the Landau gauge. In fact, {\it quark confinement originates from the low-momentum gluon below about 1.5GeV.} Finally, we consider a possible gauge of QCD for the quark potential model, by investigating "instantaneous inter-quark potential" in generalized Landau gauge, which describes a continuous change from the Landau gauge to the Coulomb gauge.

Progress of Theoretical Physics Supplement, 2007

In this write-up, we summarize our recent analysis of radiative decays involving light scalar mes... more In this write-up, we summarize our recent analysis of radiative decays involving light scalar mesons. Our analysis using the vector meson dominance model at tree level indicates that it may be difficult to distinguish qqqq picture and qq picture for the light scalar nonet. Our ...

Physical Review D, 2005

The penta-quark(5Q) baryon is studied in anisotropic quenched lattice QCD with renormalized aniso... more The penta-quark(5Q) baryon is studied in anisotropic quenched lattice QCD with renormalized anisotropy as/at=4 for a high-precision mass measurement. The standard Wilson action at β = 5.75 and the O(a) improved Wilson quark action with κ=0.1210(0.0010)0.1240 are employed on a 12 3 ×96 lattice. Contribution of excited states is suppressed by using a smeared source. We investigate both the positive-and negative-parity 5Q baryons with I = 0 and spin J = 1/2 using a non-NK-type interpolating field. After chiral extrapolation, the lowest positive-parity state is found to have a mass, mΘ = 2.25 GeV, which is much heavier than the experimentally observed Θ + (1540). The lowest negative-parity 5Q appears at mΘ = 1.75 GeV, which is near the s-wave NK threshold. To distinguish spatially-localized 5Q resonances from NK scattering states, we propose a new general method imposing a "Hybrid Boundary Condition (HBC)", where the NK threshold is artificially raised without affecting compact five-quark states. The study using the HBC method shows that the negative-parity state observed on the lattice is not a compact 5Q but an s-wave NK-scattering state.

Nuclear Physics B - Proceedings Supplements, 2005

The penta-quark(5Q) Θ + (1540) is studied in anisotropic lattice QCD with renormalized anisotropy... more The penta-quark(5Q) Θ + (1540) is studied in anisotropic lattice QCD with renormalized anisotropy as/at = 4 for a high-precision measurement. Both the positive and the negative parity 5Q baryons are studied using a non-NK type interpolating field with I = 0 and J = 1/2. After the chiral extrapolation, the lowest positive parity state is found at mΘ ≃ 2.25 GeV, which is too heavy to be identified with Θ + (1540). In the negative parity channel, the lowest energy state is found at mΘ ≃ 1.75 GeV. Although it is rather close to the empirical value, it is considered to be an NK scattering state rather than a localized resonance state.

Nuclear Physics A, 2005

Penta-quark (5Q) baryons are studied using anisotropic lattice QCD for high-precision measurement... more Penta-quark (5Q) baryons are studied using anisotropic lattice QCD for high-precision measurement of temporal correlators. A non-NK-type interpolating field is employed to study the 5Q states with J P = 1/2 ± and I = 0. In J P = 1/2 + channel, the lowest-lying state is found at m 5Q ≃ 2.25 GeV, which is too massive to be identified as the Θ + (1540). In J P = 1/2 − channel, the lowest-lying state is found at m 5Q ≃ 1.75 GeV. To distinguish a compact 5Q resonance state from an NK scattering state, a new method with "hybrid boundary condition (HBC)" is proposed. As a result of the HBC analysis, the observed state in the negative-parity channel turns out to be an NK scattering state.

Nuclear Physics A, 2005

We study the narrow decay width of low-lying penta-quark baryons in the QCD string theory in term... more We study the narrow decay width of low-lying penta-quark baryons in the QCD string theory in terms of gluonic excitations. In the QCD string theory, the penta-quark baryon decays via a gluonic-excited state of a baryon and meson system, where a pair of Y-shaped junction and anti-junction is created. Since lattice QCD shows that the lowest gluonicexcitation energy takes a large value of about 1 GeV, the decay of the penta-quark baryon near the threshold is considered as a quantum tunneling process via a highly-excited state (a gluonic-excited state) in the QCD string theory. This mechanism strongly suppresses the decay and leads to an extremely narrow decay width of the penta-quark system.

The European Physical Journal C, 2004

A gauge field link smearing method developed for calculations with staggered fermions, namely the... more A gauge field link smearing method developed for calculations with staggered fermions, namely the use of unitarized fat7 links, is applied to mesonic and baryonic Wilson loop calculations. This method is found to be very effective for reducing statistical fluctuations for large Wilson loops. Examination of chromo-electric field distributions shows that self-interactions of the static sources are reduced when unitarized fat7 smearing is used but long-distance inter-quark effects are unchanged.

AIP Conference Proceedings, 2006

Anisotropic lattice QCD studies of penta-quarks(5Q) with J P = 1/2 ± and 3/2 ± are presented at t... more Anisotropic lattice QCD studies of penta-quarks(5Q) with J P = 1/2 ± and 3/2 ± are presented at the quenched level together with tetra-quarks(4Q). The standard gauge action at β = 5.75 and O(a) improved quark (clover) action with κ = 0.1410(0.010)0.1440 are employed on the anisotropic lattice with the renormalized anisotropy a s /a t = 4. The "hybrid boundary condition(HBC)" is adopted to discriminate a compact resonance state from scattering states. Only massive 5Q states are found for J P = 1/2 + and 3/2 ± , which cannot be identified as Θ + (1540). A low-lying 5Q state is found for J P = 1/2 − at m 5Q ≃ 1.75 GeV, which however turns out to be an NK scattering state through the HBC analysis. A preliminary result for 4Q states is presented suggesting an existence of a compact 4Q resonance at m 4Q ≃ 1.1 GeV in the idealized SU(4) f chiral limit.