The Density-dependent Correlations among Observables in Nuclear Matter and Hyperon-rich Neutron Stars†
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
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†
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†
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†
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†
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†
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†
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†
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.
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)†
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†
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†
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†
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†
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†
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-†
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.
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†
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†
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†
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†
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.
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.
Hypernuclei and nuclear matter in a RMF model with chiral SU(3) potential (Kousuke Tsubakihara)†
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.
[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)†
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)†
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);
Lattice study of quarks in quark-gluon plasma (Prof. Masakiyo Kitazawa (Osaka Univ.))†
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.
Formation reaction of eta-mesic nuclei at J-PARC and chiral symmetry for baryons (Hideko Nagahiro)†
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)†
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)
Photoproduction of hyperons and resonances -- test of symmetries -- (Atsushi Hosaka)†
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).
Nonperturbative determination of the relativistic corrections to the heavy quark potential (Dr. Yoshiaki Koma)†
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 $O(1/m^2)$.
Vacuum polarization in nuclear structure (Akihiro Haga)†
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)†
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)†
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.
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