*Informal Seminar [#ebac7f39]
**The Density-dependent Correlations among Observables in Nuclear Matter and Hyperon-rich Neutron Stars [#c44775ee]
-update: 2009-07-14 (Tue)
-Date:2009/7/10(Fri.) 14:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Schun Uechi (RCNP)
-Title:The Density-dependent Correlations among Observables in Nuclear Matter and Hyperon-rich Neutron Stars
-Abstract:
--The conserving $\sigma$-$\omega$-$\rho$ mean-field approximation with nonlinear interactions of hadrons has been applied to examine properties of nuclear matter and hyperonic neutron stars.The nonlinear interactions that will produce density-dependent effective masses and coupling constants of hadrons are included in order to examine density-correlations among properties of nuclear matter and neutron stars such as binding energy, incompressibility, $K$, symmetry energy, $a_4$, and hyperon-onset density, maximum masses of neutron stars. The conditions of conserving approximations in order to maintain thermodynamic consistency to an approximation are essential for the analysis of density-dependent correlations.
-Reference:
--Advances in High Energy Physics Volume 2009 (2009), Article ID 640919, 15 pages
**Hidden gauge formalism for the radiative decays of axial-vector mesons [#z4828c55]
-update: 2009-06-23 (Tue)
-Date:2009/6/25(Thur.) 14:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Prof. Hideko Nagahiro (Nara Women's Univ.)
-Title:Hidden gauge formalism for the radiative decays of axial-vector mesons
-Abstract :
--We study the radiative decay of the axial-vector meson which is introduced as a dynamically generated resonance by pseudo-scalor and vector meson scattering. We use the vector meson Lagrangian obtained from the hidden gauge symmetry (HGS) formalism which is well suited to study this problem since it deals with pseudoscalar and vector mesons in a unified way. We show explicitly the gauge invariance of the set of diagrams that appear in the approach and evaluate the radiative decay width of the a1(1260) and b1(1235) axial-vector meson resonances into pi gamma. We also include the contribution of loops involving anomalous couplings and compare the results to those obtained previously within another formalism.
-Reference
--H. Nagahiro L. Roca A. Hosaka and E. Oset, Phys.Rev.D79, 014015 (2009)
**He4+He4 system as a gateway to alpha cluster structure and He4+n system as a gateway to nuclear shell structure [#d659217a]
-update: 2009-06-23 (Tue)
-Date:2009/5/29(Fri.) 14:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Prof. Hiroshi Toki (RCNP)
-Title:He4+He4 system as a gateway to alpha cluster structure and He4+n system as a gateway to nuclear shell structure
-Abstract:
--We are now able to handle tensor interaction in shell model framework. We shall first discuss the essence of treating tensor interaction. We then show how to include the tensor interaction in many body system using the essence of the tensor interaction. We apply this method to alpha plus alpha system and also alpha plus one nucleon system. We show a numerical method of calculating these systems explicitly using correlated gaussian method.
**Beyond mean field approximation in nuclear matter [#s6d04966]
-update: 2009-05-18 (Mon)
-Date:2009/5/15(Fri.) 14:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Dr. Jinniu Hu (RCNP)
-Title:Beyond mean field approximation in nuclear matter
-Abstract:
--As we known, the relativistic mean field (RMF) theory is very successful to description of infinite nuclear matter and finite nuclei system. However, the pion as the most important meson in strong interaction has zero contribution with the Hartree approach. Furthermore, some realistic physics effects are included in the phenomenological parameters in the RMF model such as the nucleonic response to the scalar field, the finite size of nuclei and the powerful short range repulsive in the nucleon-nucleon interaction. Therefore, in this talk, I will give some tests to study the infinite nuclear matter beyond the mean field theory. The first test is introducing the nonlinear sigma term in the effective mass. It denotes the nucleon response to the sigma field which has appeared in the quark-meson coupling (QMC) model. With this term we can largely reduce the incompressibility K of the extended chiral sigma (ESC) model to make it consistent with the experiment data very well. We also study the pion effect in the nuclear with the ESC model by using the tensor optimized shell-model (TOSM) prescription. Two particle-Two hole states are included in the variational nucleon wave function. The corresponding thing is that we also consider the fluctuation of mesons for meson field approximation. The Fock contribution of various mesons is obtained. With these Fock terms, we can study the finite size effect of nuclei and the short range correlation in the nucleon-nucleon interaction.
**Baryons in holographic QCD with curved extra-dimension [#g6c25663]
-update: 2009-05-18 (Mon)
-Date:2009/5/8(Fri.) 14:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Dr. Kanabu Nawa (RCNP)
-Title:Baryons in holographic QCD with curved extra-dimension
-Abstract:
--We study baryons[1] and baryonic matter[2] in holographic QCD with D4/D8/D8-bar multi-D brane system in type IIA superstring theory. Holography is a new concept of superstring theory as the duality between gauge theory and supergravity through D-branes. An essential property of holography is the strong-weak duality (S-duality) between gauge theory and supergravity; coupling strengths are transversely related with each other. Therefore, if QCD can be constructed on the surface of D-branes, its non-perturbative aspects can be analyzed by the tree-level dual supergravity calculation, which is called the holographic QCD. In our study, we introduce chiral soliton (Skyrmion) picture to discuss baryons in holographic QCD. We also analyze the baryonic matter in holographic QCD by placing the single Skyrmion on a three-dimensional closed manifold S^3. We propose new striking pictures for the baryonic matter as 'pion dominance' and 'swelling of baryons', which correspond to a precursory phenomena of deconfinement in dense baryonic matter. We also compare the Skyrmions in holographic QCD with those in hidden-local symmetry approach. Then we show that the roles of vector mesons for the baryon can be largely changed due to the curved extra-dimension[3].
-Reference
--[1]K. Nawa, H. Suganuma and T. Kojo, Phys. Rev. D75, 086003 (2007) [hep-th/0612187].
--[2]K. Nawa, H. Suganuma and T. Kojo, Phys. Rev. D79, 026005 (2009) [arXiv:0810.1005[hep-th]].
--[3]K. Nawa, A. Hosaka, H. Suganuma, arXiv:0901.3080[hep-th].
**phi-meson photo production with coupled channel approach [#kb53a619]
-update: 2009-05-18 (Mon)
-Date:2009/4/17(Fri.) 14:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Dr. Sho Ozaki (RCNP)
-Title:phi-meson photo production with coupled channel approach
-Abstract：
--Recently, several photon facilities have been reporting interesting results in the energy region of the strangeness (s\bar{s}) production, including the pentaquarks, \Lambda resonances and \phi-meson.
Among those, \phi-photoproduction has a unique feature such that the gluon dynamics (Pomeron contribution) dominates because the OZI rule suppress hadron dynamics due to the s\bar{s} dominance of \phi-meson. Previously, Pomeron and meson exchange model successfully reproduced differential cross sections and spin observables in the forward angle region. In 2005, LEPS group, however, has observed a peak structure near the threshold. It is known that such a structure is difficult to be explained within this model. In order to reproduce the structure we investigate coupled channel effects in the \phi-meson photoprduction. Especially we pay attention to the following two aspects. One is an on-shell kaon exchange effect in the transition amplitude \phi N\to K \Lambda(1520), which is kinematically allowed, in the energy region where a peak structure has been observed in \phi-photoproduciton. We also discuss the possibility of a nucleon resonance which may contain large s\bars components. In this seminar I discuss results of these effects.
**Nuclear breakup reaction studied by the continuum-discretized coupled-channel method with the complex scaling method [#bfe6298a]
-update: 2009-05-18 (Mon)
-Date:2009/4/10(Fri.) 14:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Dr. Masaaki Takashina (RCNP)
-Title:Nuclear breakup reaction studied by the continuum-discretized coupled-channel method with the complex scaling method
-Abstract :
--In the weakly bound nuclei (such as d, 11Be, 6He, 11Li etc.) induced reactions, the breakup process is important. However, its treatment is very difficult because one should solve three- or four-body scattering state including the target nucleus. Therefore, it is a challenging subject in the nuclear reaction theory how to describe the nuclear breakup reactions. The continuum-discretized coupled-channel (CDCC) method is known to be one of the powerful method to describe the breakup reactions [1], and has been applied for a number of the breakup reactions. Recently, the pseudo-state (PS) CDCC has been developed [2], which enables us to obtain the S matrix element as the function of the continuous momentum (k) from the discretized S matrix element using the smoothing function for the two-body breakup case. However, for the three-body breakup case, it is difficult to evaluate the smoothing function. In order to overcome this difficulty, we consider applying the complex scaling method to CDCC. The complex-scaled CDCC (CS-CDCC) is expected to give us the continuum S matrix element without the smoothing function due to the successful results of the previous study for the Coulomb breakup reaction in the external field model [3]. In this talk, we briefly introduce the CDCC method and the complex-scaling method. Then, we report the present results of the CS-CDCC method.
-Reference
--[1] M. Kamimura et al., Prog. Theor. Phys. Suppl. 89, 1 (1986).
--[2] T. Matsumoto et al., Phys. Rev. C 68, 064607 (2003).
--[3] T. Myo et al., Phys. Rev. C 63, 054313 (2001).
**The role of pions on nuclei with extended chiral Hartree model [#f227eebf]
-update: 2008-11-19 (Wed)
-Date:2008/11/20(Thurs.) 15:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Dr. Yoko Ogawa (RCNP)
-Title:The role of pions on nuclei with extended chiral Hartree model
-Abstract:
--The formalism of an extended chiral Hartree model is presented. This is a method for proper treatment of a pion-exchange interaction in the nuclear many-body problem. The dominant term of the pionic correlation is expressed in 2p-2h states with particle-holes having the quantum number not only the J$^{\pi} = 0$^{-}$ ( spherical ansatz), but also with higher spin quantum numbers, J$^{\pi} = 1^{+}, 2^{-}, 3^{+}$, ... to describe the full strength of the pionic correlation in the intermediate- and long-range region ( r > 0.5 fm ). We furthre inculde the effect of the short-range repulsion. We apply this model to $^{4}$He nucleus as a pilot calculation. We report numerical reults and the role of pions on nuclei.
**SU2_c NJL model and its hadronization in the path integral formalism [#x0f0ae8b]
-update: 2008-11-19 (Wed)
-Date:2008/11/6(Thurs.) 15:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Prof. Hiroshi Toki (RCNP)
-Title:SU2_c NJL model and its hadronization in the path integral formalism
-Abstract:
--We discuss the hadronization of NJL model lagrangian and derive the Gellmann-Levy lagrangian using the path integral method. We work out the property of quark-hadronic matter at finite temperature and density, where the confinement property of quarks is formulated in terms of the Polyakov line potential as a projection to color singlet states. We work out explicitly the case of color SU2.
**Kaon and Phi meson photoproduction [#m35624dc]
-update: 2008-10-27 (Mon)
-Date:2008/10/23(Thurs.) 15:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Dr. Sho Ozaki (RCNP)
-Title:Kaon and Phi meson photoproduction
-Abstract:
--I discuss kaon and phi meson photoproduction from the nucleon. For kaon photoproduction, we found that the QCD anomaly plays a very important role in the spin observable.
The anomalous effect renormalize to K* exchange amplitudes. This fact explains the phenomenologically determined large K* couplings used in the previous studies of the kaon photoproduction. Next, I discuss phi photoproduction. Recently, LEPS group has reported a small bump structure in the differential cross section near the threshold region. To explain the bump structure, we attempt to introduce a new reaction mechanism using coupled channel K-matrix approach and discuss the role of this mechanism in phi photoproduction.
**Vector-axialvector mixing from a chiral effective field theory at finite temperature) [#l2b94e57]
-update: 2008-07-29 (Tue)
-Date:2008/8/1 (Fri) 14:00 -
-Place : RCNP 4F Lecture Room
-Speaker : Dr. Chiriro Sasaki (TU Muenchen)
-Title:Vector-axialvector mixing from a chiral effective field theory at finite temperature)
-Abstract :
--In the presence of hot matter the vector and axialvector current correlators are mixed due to pions in the heat bath. At low temperatures this process is described in a model-independent way in terms of a low-energy theorem based on chiral symmetry and consequently the vector spectral function is modified by axialvector mesons through the mixing theorem. The validity of the theorem is, however, limited to temperatures $T << 2f_\pi$, where $f_\pi$ is the pion decay constant in vacuum. At higher temperatures one needs in-medium correlators systematically involving hadronic excitations other than pions. In this talk, we present a systematic study of the mixing (V-A mixing)in the current correlation functions and its evolution with temperature within an effective field theory. In the chiral limit the axialvector meson contributes significantly to the vector spectral function; the presence of the $a_1$ reduces the vector spectrum around the $ \rho$ meson mass $M_\rho$ and enhances it around the $a_1$ meson mass $M_{a1} $.
For physical pion mass $m_\pi$, the $a_1$ contribution above $M_ {a1}$ still survives although its strength is somewhat reduced. The a1-rho-pi coupling vanishes at the criticaltemperature $T_c$ and thus the V-A mixing also vanishes. A remarkable observation is that even for finite $m_\pi$ the $\rho$ and $a_1$ meson masses are almost degenerate at $T_c $. The vanishing V-A mixing at $T_c$ stays approximately intact.We also discuss the influence of explicit $\bar{q}q$ scalar modes on the current correlators.
**Internal One-Particle Density Matrix for > Bose-Einste in [#jaa3863d]
-update: 2008-07-29 (Tue)
-Date: July 24 (Thur.) 13:30-
-Place: Lecture room, 4th floor
-Speaker: Prof. Hisashi Horiuchi (RCNP)
-Title: Internal One-Particle Density Matrix for > Bose-Einste in Condensates with Finite Number of Particles in a Harmonic Potential Field
-Abstract:
--For the sake of clarification of the structure of the Hoyle state in 12C, we perform, as a general problem, investigations on the internal one-particle density matrix in the case of Bose-Einstein condensates with a finite number of particles in a harmonic potential field. We solve the eigenvalue problem of the Pethick-Pitaevskii-type internal density matrix and find a fragmented condensate. Since the Jacobi-type internal density matrix gives complete condensation into one state, the internal one-particle density matrix is different in general for different choices of the internal coordinate system. We propose two criteria for the choice of the adequate coordinate systems which give us a unique answer for the internal one-particle density matrix.
**Lattice study of the confinement mechanism in SU(3) Yang-Mills theory [#i38ce10a]
-update: 2008-07-22 (Tue)
-Date:2008/7/10(Thurs.) 15:00-
-Place:
-RCNP Lecture Room, 4th floor
-Speaker:Yoshiyuki Nakagawa (RCNP)
-Title:Lattice study of the confinement mechanism in SU(3) Yang-Mills theory
-Abstract:
--The properties of the gluon and ghost propagators are of prime interest in exploring the mechanism of color confinement and several approaches have been used to investigate their behaviors in the infrared region:lattice QCD simulations, Dyson-Schwinger equation and functional renormalization group equation studies. In this seminar, I report on the results of quenched lattice QCD simulations of the transverse gluon propagator, and discuss the confinement mechanism in the Coulomb gauge.
**Nature of baryons resonances - dynamical vs intrinsic [#a7785e90]
-update: 2008-06-30 (Mon)
-Date:June 19 (Thur.) 14:30-
-Place:Lecture room, 4th floor
-Speaker:Prof. Atsushi Hosaka (RCNP)
-Title: Nature of baryons resonances - dynamical vs intrinsic
-Abstract:
--From a preprint arXiv:0803.2550 [nucl-th] We study the origin of the resonan ces associated with pole singularities of the scattering amplitude in the ch iral unitary approach. We propose a “natural renormalization” scheme using the low energy interaction and the general principle of the scattering theo ry. We develop a method to distinguish dynamically generated resonances from genuine quark states (CDD poles) using the natural renormalization scheme a nd phenomenological fitting. Analyzing physical meson-baryon scatterings, we find that the Λ(1405) resonance is largely dominated by the meson-baryon m olecule component. Contrary, the N(1535) resonance requires a sizable CDD po le contribution, while the effect of the meson-baryon dynamics is also important.
**Bridging p-wave pi-production and weak processes in few-nucleon systems with chiral perturbation theory [#r756f538]
-update: 2008-06-13 (Fri)
-Date:2008/6/13(Fri.) 16:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Dr. Satoshi Nakamura(TRIUMF)
-Title:Bridging p-wave pi-production and weak processes in few-nucleon systems with chiral perturbation theory
-Abstract:
--I study an aspect of chiral perturbation theory (\chi PT) which enables one to ``bridge'' different reactions. That is, an operator fixed in one of the reactions can then be used to predict the other. For this purpose, I calculate the partial wave amplitude for the p-wave pion production (pp\to pn\pi^+) using the pion production operator from the lowest and the next nonvanishing orders. The operator includes a contact operator whose coupling has been fixed using a matrix element of a low-energy weak process (pp\to de^+\nu_e). I find that this operator does not reproduce the partial wave amplitude extracted from experimental data, showing that the bridging over the reactions with significantly different kinematics is not necessarily successful. I study the dependence of the amplitude on the various inputs such as the NN potential, the \pi N\Delta coupling, and the cutoff. I argue the importance of a higher order calculation. In order to gain an insight into a higher order calculation, I add a higher order counter term to the operator used above, and fit the couplings to both the low-energy weak process and the pion production. The energy dependence of the partial wave amplitude for the pion production is described by the operator consistently with the data. However, I find a result which tells us to be careful about the convergence of the chiral expansion for the pp\to pn\pi^+ reaction.
**Radiative decays of the low lying axial-vector mesons [#bb130724]
-update: 2008-06-12 (Thu)
-Date:2008/6/12(Thurs.) 15:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Dr. Hideko Nagahiro (RCNP,Theory Group)
-Title:Radiative decays of the low lying axial-vector mesons
-Abstract :
--We evaluate the radiative decay widths into a pseudo-scalar meson and a photon of the low lying axial vector mesons, a1(1260), b1(1235), h1(1170), h1(1380), f1(1285) and K1(1270) [1,2], which are dynamically generated from the vector-pseudoscalar interaction with the Chiral Unitary approach. [3] The radiative decay widths are useful observables to study the nature of the resonances. Especially, in the Chiral Unitary approach, two K1(1270) resonances were found [3,4] in analogy with the two poles of the Lambda(1405).
We would like to discuss that, if one considers the doublet pole structure of K1 in the experimental analysis of the radiative decay, the obtained experimental result in Ref.[5] could be changed. I would like to show our results based on Ref.[1,2] and also show very recent developments (still in progress) of our study [6].
-References:
--[1] H. Nagahiro, L. Roca and E. Oset, Phys.Rev.D77, 034017 (2008). H. Nagahiro, L. Roca and E. Oset, Eur. Phys. J. A 36, 73 (2008). H. Nagahiro, L. Roca, E. Oset and B. S. Zou arXiv:0803.4460 [hep-ph], 2 June 2008 PRD accepted.
--[2] L. Roca, A. Hosaka and E. Oset, Phys.Lett.B658,17-26 (2007).
--[3] L. Roca, E. Oset and J. Singh, Phys.Rev.D72,014002 (2005).
--[4] L.S. Geng, E. Oset, L. Roca, J.A. Oller, Phys.Rev.D75,014017 (2007).
--[5] A. Alavi-Harati et al., Phys.Rev.Lett.89,072001 (2002).
--[6] A. Hosaka, H. Nagahiro, L. Roca and E. Oset, in progress.
**Trial of tensor optimized AMD formalism for nuclear structure -case of deuteron as two particle system- [#fb739856]
-update: 2008-05-28 (Wed)
-Date:2008/5/29(Thurs.) 15:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Prof. Hiroshi Toki (RCNP,Theory Group)
-Title:Trial of tensor optimized AMD formalism for nuclear structure -case of deuteron as two particle system-
-Abstract:
--I shall speak in English so that Chen-san and Hu-san can understand the content. This is just a trial stage, but it may be good to discuss with many people internally at this moment. I hope audience can understand the essential point of the treatment of tensor interaction for nuclear structure.
Here, AMD stands for anti-symmetrised molecular dynamics.
**Baryonic matter in holographic QCD [#nf56b117]
-update: 2008-05-22 (Thu)
-Date:May 22 (Thurs.) 15:00-
-Place:Lecture room, 4th floor
-Speaker:Dr. Kanabu Nawa (RCNP)
-Title:Baryonic matter in holographic QCD
-Abstract:
--We study baryons[1] and baryonic matter[2] in holographic QCD with D4/D8/\bar{D8} multi-D brane configurations in type IIA superstring theory. 'Holography' is a new concept of superstring theory as the duality between gauge theory and supergravity mediated by the D-branes. Most essential property of holography is the existence of strong-weak duality between gauge theory and supergravity; couplings are transversely related with each other. Therefore, if one can construct QCD with quarks and gluons on the special configuration of D-branes, he can attack the non-perturbative aspects of QCD by the tree-level dual supergravity calculation, which is called the holographic QCD.
In our study, we introduce the concept of chiral soliton (Skyrmion) picture to discuss baryons in holographic QCD. We also analyze the baryonic matter in holographic QCD by placing the single Skyrmion on a three- dimensional closed manifold S^3. We propose new striking pictures for the baryonic matter as 'pion dominance' and 'swelling of baryons', which could be regarded as some precursory phenomena of deconfinement in dense baryonic matter.
-References:
--[1]K. Nawa, H. Suganuma and T. Kojo, Phys. Rev. D75, 086003 (2007) [hep-th/0612187].
--[2]K. Nawa, H. Suganuma and T. Kojo in preparation.
**Clustering and deformation in p- and sd-shell nuclei [#ucb8f673]
-update:2008-05-13 (Tue)
-Date:2008/5/15(Tsu.)15:00-
-Place: RCNP Lecture Room, 4th floor
-Speaker: Dr. Yasutaka Taniguchi (RCNP,Theory Group)
-Title: Clustering and deformation in p- and sd-shell nuclei
-Abstract:
--We have interests in drastic changes of nuclear structures.Clustering and deformation are typical ones. In many cases, cluster and deformed structures coexist and mix. Therefore, it is necessary to treat clustering and deformation explicitly in order to understand nuclear systems. We proposed a unified manner to treat clustering and deformation by constraints in energy variation and generator coordinate method based on antisymmetrized molecular dynamics (AMD). We will talk about brief explanation of a framework of AMD and its application to studies of clustering and deformation in p- and sd-shell nuclei.
**The Los Alamos neutron electric dipole moment experiment [#xde82287]
-update: 2008-05-08 (Thu)
-Date:2008/5/9(Fri.)16:00-
-Place:RCNP Lecture Room, 4th floor
-Speaker:Prof. Robert Colub(North Carolina State University)
-Title:The Los Alamos neutron electric dipole moment experiment
-Abstract:
--A collaboration centered on the Los Alamos lab hs been developing the concepts and design for a high sensitivity search for the neutron electric dipole moment using Ultra cold neutrons produced in super fluid He4 with polarized He3 as a a polarization analyzer and detector. We will give an overview of the project and discuss the major systematic error associated with the geometric phase or Bloch-Sigert shift produced by the motional (v X E) magnetic fields and the methods for dealing with it.
**ISGMR AND ISOSCALAR AND ISOVECTOR NUCLEAR MATTER PROPERTIES [#jbab1b88]
-update:2008-05-02 (Fri)
-Date:2008/5/2 (Tue.) 16:00 -
-Place:RCNP 4F Lecture Room
-Speaker : Prof. Hirouki Sagawa ( The University of Aizu )
-Title:ISGMR AND ISOSCALAR AND ISOVECTOR NUCLEAR MATTER PROPERTIES
-Abstract :
--The isoscalar and isovector nuclear matter properties are investigated in the Skyrme Hartree-Fock (SHF) and relativistic mean field (RMF) models. The correlations between the nuclear matter incompressibility and the isospi n dependent term of the finite nucleus incompressibility is elucidated by us ing various different Skyrme Hamiltonians and RMF Lagrangians. Microscopic HF+random phase approximation (RPA) calculations are performed with F+Skyrme in teractions for 208Pb and Sn isotopes to study the strength distributions of isoscalar giant monopole resonances (ISGMR). The symmetry term of nuclear in compressibility is extracted to be K = −(500± 50) MeV from the recent experimental data of ISGMR in Sn isotopes.
**$\\alpha$ inelastic scattering on $^12$C exciting the $\\alpha$ condensate state [#t0d9b49d]
-update: 2008-04-24 (Thu)
-Date: April 24 (Thurs.) 13:00-
-Place: Lecture room, 4th floor
-Speaker: Dr. Masaaki Takashina (RCNP)
-Title: $\\alpha$ inelastic scattering on $^12$C exciting the $\\alpha$ condensate state
-Abstract:
--The 0$_2^+$ state in $^{12}$C is a typical example of $\\alpha$ clustering phenomenon in nuclear system. In the recent theoretical studies, it has been shown [1] that $^{12}$C(0$_2^+$) could be interpreted as an $\\alpha$- particle condensate state. One of the remarkable features of the $\\alpha$ condensate state is the considerably large nuclear radius compared with the ground state. Therefore, if the large nuclear radius of the candidate state is experimentally confirmed, it will be a strong evidence that indicates the formation of the $\\alpha$ condensate state. In the present study, we analyze the $\\alpha$ inelastic scattering on $^12$C exciting the 0$_2^+$ state, and investigate whether the evidence of the large nuclear radius of this state appears in the inelastic angular distribution, or not. [1] A. Tohsaki et al., Phys. Rev. Lett. 87 (2001) 192501.
**アルファ凝縮と核子 [#o811b992]
-update:2008-04-18 (Fri)
-Date:April 18 (Fri.) 16:00-
-Place:Lecture room, 4th floor
-Speaker: Akihiro Tosaki (RCNP)
-Title:アルファ凝縮と核子
-Abstract:
--N個のα粒子が共通の(0s)‐軌道に属する状態、α凝縮状態の存在が予想されて8年になる。理論先行の予想である。というのも、微視的に記述することのできる波動関数が提唱されたことが主な原因である。フェルミ粒子を構成粒子とするボーズ粒子からなる凝縮系の記述は必然的に微視的模型が最善となる。原子系とは異なり、中性ではない粒子からなる凝縮状態を安定性を保証するものは核力とクーロン力の競合による斥力壁である。今回は、その模型波動関数の簡単な紹介と、その波動関数に核子を付加する系の定式化、具体的には共鳴群法による定式化を紹介する。例として、私が主として関わった12C 、13C、 13Nを取り上げる。
**Exotic Hadrons in the QCD Sum Rule [#b64d86e8]
-update:2008-02-13 (Wed)
-Date:February 15 (Fri.) 16:00-
-Place:Lecture room, 4th floor
-Speaker:Dr. Hua-Xing Chen (RCNP)
-Title:Exotic Hadrons in the QCD Sum Rule
-Abstract:
--The theory of the strong interactions, Quantum Chromodynamics (QCD), originated from the systematics of hadron spectroscopy. The spectroscopy contains meson and baryon states. Besides the quark model, QCD allows much richer hadron spectrum such as multiquark states, hadron molecules, hybrid states, glueballs etc. We study the mass of several exotic states in the QCD sum rule. They are scalar mesons, Y(2175), pi_1(1400) and pi_1(1600), etc.
**Baryon-Baryon interaction in the chiral quark model [#y029f238]
-update: 2008-01-24 (Thu)
-Date:January 24 (Thu.) 10:30-
-Place:Lecture room, 4th floor
-Speaker:Prof. L. Dai (Dalian/RCNP)
-Title:Baryon-Baryon interaction in the chiral quark model
**Hypernuclei and nuclear matter in a RMF model with chiral SU(3) potential (Kousuke Tsubakihara) [#m6d118b0]
-update:2008-01-08 (Tue)
-Date:December 20 (Tur.) 16:00-
-Place:Lecture room, 4th floor
-Speaker:Kousuke Tsubakihara (Hokkaido University)
-Title:Hypernuclei and nuclear matter in a RMF model with chiral SU(3) potential
-Abstract:
--In constructing the dense matter equation of state (EOS), it is desired to respect both chiral symmetry and hypernuclear physics. In dense matter, strangeness is expected to play a decisive role and the partial restoration of chiral symmetry would modify the hadron properties. For chiral symmetry side, We have recently developed an RMF model with
chiral SU(2) potential[1] with logarithmic sigma potential in the form of $-\log\sigma$, which is derived in the strong coupling limit (SCL) of the lattice QCD[2]. In this paper, we briefly show that we can describe not only symmetric nuclear matter but also bulk properties of finite nuclei. On the other hand, from a viewpoint of hypernuclear physics, we develop a extended chiral SU(3) RMF model which include both of chiral symmetry and hypernuclear physics informations[3]. We determine the hyperon-meson coupling constants in this chiral SU$_{f}$(3) RMF model by fitting existing data. We can reproduce the separation energies of single $\Lambda$ hypernuclei ($S_\Lambda$) and the $\Lambda\Lambda$ bond energy ($\Delta B_{\Lambda\Lambda}$) in $^6_{\Lambda\Lambda}$He by choosing the coupling constants appropriately in a reasonable parameter range. In this seminar, we present this RMF model including chiral SU(3) potential and its results. In addition, we discuss nuclear star in this chiral SU(3) RMF model and show an effect to nuclear star maximum mass by introducing this potential.
-Reference:
--[1] K.~Tsubakihara and A.~Ohnishi, Prog. Theor. Phys. {\bf 117}, (2007) 903.
--[2] N. Kawamoto and J. Smit, Nucl. Phys. B {\bf 190}, (1981) 100; N. Kawamoto, K. Miura, A. Ohnishi and T. Ohnuma, Phys. Rev. D {\bf 75}, (2007) 014502.
--[3] K.~Tsubakihara, H.~Maekawa and A.~Ohnishi, Eur. Phys. J. A {\bf 33} (2007) 295.
**Kaon photoproduction with the anomaly (Sho Ozaki) [#h486d82f]
-update:2008-01-08 (Tue)
-Date:December 13 (Thu.) 16:00-
-Place:Lecture room, 4th floor
-Speaker:Sho Ozaki (RCNP)
-Title:Kaon photoproduction with the anomaly
-Abstract:
--We study the role of magnetic interaction in the photoproduction of the kaon and hyperon [1]. We find that the inclusion of a higher order diagram induced by the Wess-Zumio-Witten term [2] has a significant contribution to the magnetic amplitude, which is compatible to the observed photon asymmetry in the forward angle region. This enables us to use the K* coupling constants which have been determined in a microscopic way [3] rather than the phenomenological ones [4] which differ largely from the microscopic ones.
-Reference:
--[1]S. Ozaki, H. Nagahiro, A. Hosaka arXiv:0710.5581 [hep-ph]
--[2]E. Witten Nuc. Phys. B223 (1983) 422-432
--[3]A. Reuber, K. Holinde, J. Speth Nuc. Phys. A570 (1994) 543-579
--[4]F.X. Lee, T. Mart, C. Bennhold, H. Haberzettl, L.E. Wright Nuc. Phys. A 695 (2001) 237-272
**The role of pions on nuclei with charge and parity projected chiral mean field model (Dr. Yoko Ogawa) [#p8c12996]
-update:2008-01-08 (Tue)
-Date:November 30 (Fri.) 16:00-
-Place:Lecture room, 4th floor
-Speaker:Dr. Yoko Ogawa (RCNP)
-Title:The role of pions on nuclei with charge and parity projected chiral mean field model
-Abstract :
--We study the role of pions on the ground states of finite nuclei with explicit introduction of pions by constructing a new relativistic framework on the basis of the mean field theory. The pseudoscalar nature of pions introduces the high momentum correlations in the interaction between nucleons. In order to describe this important nature in the wave function, our framework treats the correlation between 0p-0h and 2p-2h states which is the main ingredient in the pionic correlations by using the charge and parity mixed
single-particle states as a basis with the variation after charge number and parity projection scheme. The pion is the Nambu-Goldstone particle of the spontaneous chiral
symmetry breaking, and hence, the use of the linear sigma model Lagrangian for the nuclear physics indicates unification of the quark, hadron and nuclear physics. This framework first has been applied to $^{4}$He as a pilot case and demonstrated to provide good ground state properties. A depression appears in the central region of the density distribution.
The second maximum and the position of the dip in the form factor of $^{4}$He are naturally obtained in this framework. The pseudoscalar nature or the high momentum correlations are indicated in the large amount of the second maximum of the form factor. We further apply this framework to heavier nuclei up to $^{56}$Ni. The pionic correlations reflect largely the particle configurations in the shell structure. The pionic energy systematics as a function of the nuclear mass number are clearly separated into two groups, the LS and jj closed-shell nuclei. This large difference of the pionic correlation energy between LS and jj closed-shell nuclei indicates an important role of pions on the formation of the jj magic numbers. The explicit introduction of pions give one possibility to solve the problem of spin-orbit single particle structure for the large effective nucleon mass.
-Reference
--Toki et al, Prog. in Part. and Nucl. Phys. {\bf 59}, 209(2007);
--Phys. Rev. {\bf C73}, 034301(2006); {\bf C76}, 014305(2007).
**格子QCD計算によるクーロンゲージでのカラー閉じ込め機構の研究 (Yoshiyuki Nakagawa) [#y06bd6f9]
-update:2008-01-08 (Tue)
-Date:November 2 (Fri.) 16:00-
-Place:Lecture room, 4th floor
-Speaker:Yoshiyuki Nakagawa (RCNP)
-Title:格子QCD計算によるクーロンゲージでのカラー閉じ込め機構の研究
-Abstract :
--量子色力学(QCD)の基本粒子であるクォークやグルーオンはハドロンに閉じ込められていてこれらを単独で観測することはできません。この現象はカラー閉じ込めと呼ばれ、その機構を明らかにすることは
数理物理学、原子核物理学における大問題となっています。QCDは漸近自由な理論であるため、低エネルギーでは結合定数が大きくなり、摂動論を適用することができません。そこで我々はQCDの非摂動論的な計算手法である格子QCDの数値シミュレーションを用いることで、カラー閉じ込めの機構の解明に取り組んでいます。
--今回のセミナーでは次のような話をする予定です。
---(1) どのような物理量をみてクォーク／グルーオンの閉じ込めを議論するのか
---(2) LandauゲージにおけるDyson-Schwinger方程式の解析からみえる
--ゴーストの重要性
---(3) そもそもゴーストとは何か
---(4) Coulombゲージでの閉じ込め力の起源とゴーストとの関連性
-格子QCDについては結果を見せるだけで、詳しいことは説明しないと思います。格子QCDに興味がある方は広島大学の中村純先生の集中講義を聞きにいってください。日時は11月7日(水)~9日(金)、場所は豊中理学部棟のE210です。
**Y-string potential in baryons (Prof. Veljko Dmitrasinovic) [#wc95c876]
-update:2008-01-08 (Tue)
-Date:November 1 (Thu.) 16:00-
-Place:Lecture room, 4th floor
-Speaker:Prof. Veljko Dmitrasinovic
-Title:Y-string potential in baryons
**Lattice study of quarks in quark-gluon plasma (Prof. Masakiyo Kitazawa (Osaka Univ.)) [#rc2d6d1b]
-update:2008-01-08 (Tue)
-Date:October 23 (Tues) 16:30-
-Place:Lecture room, 4th floor
-Speaker:Prof. Masakiyo Kitazawa (Osaka Univ.)
-Title:Lattice study of quarks in quark-gluon plasma
-Abstract:
--We analyze the spectral properties of the quark propagator above the critical temperature for the deconfinement phase transition in quenched lattice QCD using clover improved Wilson fermions. The bare quark mass dependence of the quark spectral function is analyzed by varying the hopping parameter $\kappa$ in Landau gauge. We assume a two-pole structure for the quark spectral function, which is numerically found to work quite well for any value of $\kappa$. It is shown that in the chiral limit the quark spectral function has two collective modes that correspond to the normal and plasmino excitations, while it is dominated by a single-pole structure when the bare quark mass becomes large.
-Reference:
--F. Karsch and M. Kitazawa, arXiv:0708.0299
**Unitary correlationi operator methodによる短距離相関の記述とTensor-optimized shell modelへの適用 (Takayuki Myo) [#a9b960c6]
-update:2008-01-08 (Tue)
-Date:October 19 (Fri) 16:00-
-Place:Lecture room, 4th floor
-Speaker:Dr. Takayuki Myo (RCNP)
-Title:Unitary correlationi operator methodによる短距離相関の記述とTensor-optimized shell modelへの適用
-Abstract :
--核構造においてテンソル相関と短距離相関は重要な核力相関である。これまで我々は前者のテンソル相関に注目し、中性子ハロー核を中心とした軽い中性子過剰核における顕わなテンソル力の効果を解明してきた。具体的成果は
---1. テンソル力を顕わに扱う為に、He 及びLi 同位体に殻模型の配位混合を二粒子二空孔まで施し、かつ調和振動子基底の拡がりを変分的に扱った(tensor-optimized shell model)。結果、大きなテンソル力の寄与を収束して得た[1]。
---2. 特に11Li では、テンソル相関を稼ぐことで(1s)2 配位が系全体としてエネルギーを得し、その結果、ハロー構造が自然に説明された[2]。
--但し、短距離相関を現象論的に処理してきた。そこで次段階として現実的核力から生じる短距離相関の取り込みを行う。手法にユニタリー相関演算子法(Unitary Correlation Operator Method, UCOM[3])
を用いる。UCOMでは、核内の全ての相対波動関数に対して短距離斥力を避けるユニタリー相関演算子を導入する。実際は相関演算子をハミルトニアンに作用させ、変換されたハミルトニアンの固有状態を模型波動関数の基で解く。今回はtensor-optimized shell modelへ適用することで短距離相関とテンソル相関の両方の記述を試みる。
-Reference:
--[1] T. Myo, S. Sugimoto, K. Kato, H. Toki, K. Ikeda, Prog. Theor. Phys. 117 (2007) 257.
--[2] T. Myo, K. Kato, H. Toki, K. Ikeda, Phys. Rev. C. (2007) 024305.
--[3] H. Feldmeier, T. Neff, R. Roth and J. Schnack, Nucl. Phys. A632 (1998) 61.
**Formation reaction of eta-mesic nuclei at J-PARC and chiral symmetry for baryons (Hideko Nagahiro) [#h28f24df]
-update: 2008-01-08 (Tue)
-Date : July 27 (Fri) 16:00-
-Place : Lecture room, 4th floor
-Speaker : Dr. Hideko Nagahiro (RCNP)
-Title : Formation reaction of eta-mesic nuclei at J-PARC and chiral symmetry for baryons
-Abstract :
--We investigate the properties of eta-nucleus interaction in chiral models and their experimental consequences at J-PARC project. The strong coupling of the eta-nucleon system to the N*(1535) resonance enables us to investigate the in-medium properties of N* through the formation of eta-mesic nuclei. In order to evaluate the in-medium properties of N*, we use two
different chiral models, which have quite different pictures for N* and give quite different predictions for in-medium behaviors of N*. In this talk, I would like to show that we can clearly observe this difference in the formation spectra and get new information of the eta-nucleus interaction and the chiral symmetry in medium.
**Triplet-even channel attraction for single-particle energies (Dr. Atushi Umeya) [#x7d0a8f7]
-update: 2008-01-08 (Tue)
-Date : July 20 (Fri) 16:00-
-Place : Lecture room, 4th floor
-Speaker : Dr. Atushi Umeya (Osaka Electro-Communication University)
-Title : Triplet-even channel attraction for single-particle energies
-Abstract :
--One of the most striking features in neutron-rich nuclei is the disappearance of magic number N = 8 or 20, which indicates a change of single-particle energy spectra and the disappearance
of a large energy gap at the magic number. A sum-rule method is formulated, based on the shell model, for the evaluation of single-particle energies. It is shown that the triplet-even central component of the NN interaction plays a decisive role through the monopole interaction for a change of single-particle energy spectra, leading to a rapid decrease of the energy gap at N = 8 and 20.
The triplet-even attraction is due partly to the original central interaction and partly to the second-order tensor correlations of the one-pion exchange potential. A multipole expansion analysis of NN interactions shows that the contribution to the single-particle energy from the monopole interactions between two orbits depends on the nodal quantum numbers of the orbits.
-Reference:
--A. Umeya and K. Muto, 'Single-particle energies in neutron-rich nuclei by shell model sum rule', Phys.Rev.C74, 034330 (2006)
**集中講義 [#sea935de]
-update: 2008-01-08 (Tue)
-Date : July 13 (Fri) 13:00-
-Prof. Yuko Mochizuki (RIKEN)による集中講義（阪大豊中キャンパス）
**Photoproduction of hyperons and resonances -- test of symmetries -- (Atsushi Hosaka) [#ffb6bdb8]
-update: 2008-01-08 (Tue)
-Date : July 6 (Fri) 16:00-
-Place : Lecture room, 4th floor
-Speaker : Prof. Atsushi Hosaka (RCNP)
-Title : Photoproduction of hyperons and resonances -- test of symmetries --
-Abstract:
--We discuss photoproductions of hyperons and resonances to test flavor, chiral and gauge symmetries of the strong interactions. Three examples are discussed;
---(1) Kroll-Ruderman term for the L(1520) production,
---(2) U-spin symmetry for the production of N*(1670) resonance
---(3) Flavor SU(3) for K* coupling to N-Lambda(1116).
**Baryons from instantons in holographic QCD (酒井忠勝 (茨城大学理学部准教授)) [#y5338f3d]
-update: 2008-01-08 (Tue)
-時間 : 2007/6/29(金)16:00〜
-場所 : 大阪大学吹田キャンパス 核物理研究センター（RCNP) 4F Lecture Room
-talker : 酒井忠勝 (茨城大学理学部准教授)
-タイトル : Baryons from instantons in holographic QCD
-アブストラクト :
--本講演において, D4/D8ブレインを用いて構成された QCD のholographic dual なモデルの枠組の中で, バリオンをいかに記述するかを議論する。このモデルで中心的な役割を果たすのが5次元の YM 理論に CS項が加わった系である。この時バリオンがYM インスタントン解として表されることを見る。さらにこの解を量子化することによりバリオンの質量スペクトラムを求め, 実験結果と比較する。特に negative parity をもつバリオンが非常に簡単に記述できるなどの興味深い結果が得られる。
**Nonperturbative determination of the relativistic corrections to the heavy quark potential (Dr. Yoshiaki Koma) [#w86fff19]
-update: 2008-01-08 (Tue)
-Date : June 22 (Fri) 13:00-
-Place: Lecture room, 4th floor
-Speaker:Dr. Yoshiaki Koma (Numazu College of Technology) 駒 佳明（沼津高専）
-Title : Nonperturbative determination of the relativistic corrections to the heavy quark potential
-abstract:
--Heavy quarknia, bound states of a heavy quark and antiquark, offer a unique opportunity to gain an understanding of nonperturbative QCD. A possible way of studying such systems systematically in QCD is to employ (potential) nonrelativistic QCD, which provides the static inter-quark potential as the leading order contribution, followed by relativistic corrections in powers of $1/m$ with quark mass $m$. The various properties of heavy quarkonium can be extracted by solving the Schroedinger equation with these potentials. We present our recent numerical results of the relativistic corrections
to the static potential obtained by using lattice QCD Monte Carlo simulations, which include the potential at $O(1/m)$ as well as the spin-dependent potentials at $O(1/m^2)$.
**Pions in Nuclei（原子核におけるパイオン） (Hiroshi Toki) [#l21a2d6b]
-update: 2008-01-08 (Tue)
-Speaker : Hiroshi Toki
-Date and time : 5/25 (Fri) 16:00pm-
-Place : Lecture room, 4th floor
-Title : Pions in Nuclei（原子核におけるパイオン）
-Abstract :
--パイオンの原子核での働きについて話をする。シェルモデルが存在するのに何故，今の段階でパイオンを入れた原子核モデルを構築したいかを議論する。その上で現在の研究の段階を説明する。今後、どのようにして研究を進めるかの話をする。スピン軌道力の起源、ガモフテラーの分散と幅が狭いことの理由等についての話をする。共同研究者は小川，為永、明、芳賀さんたちであり、その結果を使いながら話を組み立てたい。
**Vacuum polarization in nuclear structure (Akihiro Haga) [#vd508328]
-update: 2008-01-08 (Tue)
-Speaker : Akihiro Haga
-Date and time : 5/18 (Fri) 16:00pm-
-Place : Lecture room, 4th floor
-Title : Vacuum polarization in nuclear structure
-Abstract :
--The negative energy contribution in the relativistic nuclear model is discussed. First, I'd like to show the importance of the negative energy nucleon states for the muonic energy levels in a heavy nucleus. This importance is caused by the small effective mass, which is considered to be required to yield the appropriate spin-orbit force. Including the negative energy contribution into the structure of nucleus self-consistently, namely, vacuum polarization effect, however, it is found that the effective mass is so large that the nuclear excitations are reproduced better. In this talk, I'd like also to show the vacuum polarization effect in the Dirac-Brueckner-Hartree-Fock calculation using the realistic nucleon-nucleon force.
**The sub-shell structure in the RMF theory (Setsuo Tamenaga) [#yc5f8f93]
-update: 2008-01-08 (Tue)
-Speaker : Setsuo Tamenaga
-Date and time : 5/11 (Fri) 16:00pm-
-Place : Lecture room, 4th floor
-Title : The sub-shell structure in the RMF theory
-Abstract:
--Magic number is a very important concept in many subjects of physics, such as atomic physics, nuclear physics and micro cluster physics. In the nuclear physics, nuclei with magic numbers have been hot topics of nuclear research since the beginning of this subject. A systematic study has been done for the ground-state properties of a total of 6969 nuclei with $Z$, $N\geq 8$ and $Z\leq 100$ from the proton drip line to the neutron drip line which includes the binding energies, the separation energies, the deformations, and rms charge radii by using the TMA parameter set within the RMF framework and
\textit{no-sea approximation}. It is found that the RMF theory has proved to be very successful in describing many nuclear properties, due to its natural spin-orbit description and only a few parameters for not only stable nuclei but also exotic nuclei. However, this study indicate a (sub)shell closure ($1g_{7/2}$) at $Z=58$, where $^{140}_{58}$Ce$_{82}$ is studied as a doubly magic nucleus and
another one ($1h_{9/2}$) at $Z=92$, where $^{218}_{92}$U$_{126}$ is studied as a doubly magic nucleus. The behavior of other often used parameter sets in the RMF theory indicates that this is common to almost all the existing parameter sets. We would like to discuss the appearance of the subshell closures at $Z=58$ and $Z=92$ by using the RMF model, which includes the relativistic Hartree approach (RHA), linear sigma model, and chiral effective field theory (EFT).
**Meson-Meson scattering in the SU(3) linear sigma model (C.Y. Ryu) [#z8e37e28]
-update: 2008-01-08 (Tue)
-Speaker : C.Y. Ryu
-Date and time : 4/26 (Thu) 16:00pm-
-Place : Lecture room, 4th floor
-Title : Meson-Meson scattering in the SU(3) linear sigma model
-abstract:
--We caluclate the meson-meson scattering in SU(3) Linear sigma model, applying Gaussian Functional Approximation (GFA). We use SU(3) linear sigma model with scalar and pseudoscalar nonet to calculate the masses of scalar mesons and obtain the self-consistent gap equations through GFA. With GFA method, assuming that the solution of the Schroedinger equation in linear sigma model is the Gaussian funtion and applying the variational method that minimize vacuum energy, we obtain t-matrix including all pseudoscalar and scalar mesons as intermediate states. The spectral function of meson-meson scattering is calculated by using Bethe-Salpeter equation. The solutions of gap equations and Bethe-Salpeter equations are presented.
**Nonperturbative approach to QCD - Applications of lattice QCD - (Hideaki Iida) [#x151391f]
-update: 2008-01-08 (Tue)
-Speaker : Hideaki Iida
-Date and time : 4/19 (Thu) 16:00pm-
-Place : Lecture room, 4th floor
-Title : Nonperturbative approach to QCD - Applications of lattice QCD -
-Abstract:
--格子QCDは、カラーの閉じ込めやカイラル対称性の自発的破れなどの、QCDの非摂動現象に対する唯一の第一原理計算である。多くの先達の研究により、近年、格子QCDは数値実験としての地位を確立しつつある。一方で、波動関数を扱い難いことや、有限密度系における計算がsign problemによって困難であることなど、解析的手法に比較して不利な点も存在する。今回のセミナーでは、上記の問題を克服する（または迂回する）試みとして、我々が現在までに行ってきた、格子QCDの「応用的使用法」を紹介する。具体的には、
---(1) 格子QCDデータに基づいたシュウィンガー・ダイソン方程式の構築、およびその有限温度・密度系への応用 [1]
---(2) 境界条件を用いた、相転移温度T_c以上におけるチャーモニウムの存在の判定[2]
---(3) スカラーQCDにおけるスカラークォークの質量生成 [3]
に関して話す予定である。このセミナーで、格子QCDを「道具として」身近に感じていただければ幸いです。
-（参考文献）
-[1] H. Iida, M. Oka and H. Suganuma, Eur. Phys. J. A23 (2005) 305; Nucl. Phys. Proc. Suppl. 141 (2005) 191.
-[2] H. Iida, T. Doi, N. Ishii, H. Suganuma and K. Tsumura, Phys. Rev. D74 (2006) 074502.
-[3] H. Iida, H. Suganuma and T.T. Takahashi, hep-lat/0703019.
**Baryons in Holographic QCD (Kanabu Nawa) [#yf94674c]
-update: 2008-01-08 (Tue)
-Speaker : Kanabu Nawa
-Date and time : 4/13 (Fri) 16:00pm-
-Place : Lecture room, 4th floor
-Title : Baryons in Holographic QCD
-Abstract:
--量子色力学(QCD)は、SU(3)の非可換ゲージ理論であり、クォークとグルーオンの自由度を支配する「強い相互作用」の基礎理論であると考えられている。
QCDは特にその非可換性のために、漸近的自由性という特徴的な性質を有し、低エネルギースケールで非摂動的に相互作用が強くなるため、真空自身に多彩な変質を与えることが予言されている。例えば、クォークと反クォークが対を組んで真空中に凝縮し、この凝縮体が物質の質量の起源を与える（カイラル対称性の自発的破れ）。また、クォークやグルーオンのような‘色’を帯びた粒子は、‘無色’な中間子やバリオンの中に閉じ込められる（カラー閉じ込め現象）。
その他にも、ゲージ場であるグルーオンが持つ非線型な相互作用は、真空自身にトポロジカルな変質としてのインスタントンを誘起し、これが$\eta^'$中間子の大きな質量を説明するものと考えられている。このように、QCDは非摂動領域に多彩な変質を持ち、非常に興味深い領域であるが、一方で、QCDの相互作用によるナイーブな摂動論が適応できないという意味で解析困難な領域にもなっている。ところが、2005年、酒井・杉本によって、超弦理論から新たな枠組が提案された[1]。これは、QCDの非摂動領域の性質を、超弦理論の摂動論で解析可能にするという枠組であり、広く「ホログラフィックQCD」と呼ばれる。今回のトークでは、このホログラフィックQCDの概観と、そこでのバリオンの研究[2]について紹介する。
-[参考文献]
--[1]T.Sakai and S.Sugimoto, Prog. Theor. Phys. 113, 843（2005)；114, 1083 (2005).
--[2] K.Nawa, H.Suganuma, and T.Kojo, 'Baryons in Holographic QCD', Phys. Rev. D in press [hep-th/0612187].
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