16 results on '"Yasui, S."'
Search Results
2. Heavy quark symmetry in multi-hadron systems
- Author
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Yamaguchi, Y., Ohkoda, S., Hosaka, A., Hyodo, T., and Yasui, S.
- Subjects
High Energy Physics - Phenomenology ,Nuclear Theory - Abstract
We discuss the properties of hadronic systems containing one heavy quark in the heavy quark limit. The heavy quark symmetry guarantees the mass degeneracy of the states with total spin and parity $(j-1/2)^{P}$ and $(j+1/2)^{P}$ with $j \geq 1/2$, because the heavy-quark spin is decoupled from the total spin $j$ of the light components called brown muck. We apply this idea to heavy multi-hadron systems, and formulate the general framework to analyze their properties. We demonstrate explicitly the spin degeneracy and the decomposition of the wave functions in exotic heavy hadron systems generated by the one boson exchange potential. The masses of the brown muck can be extracted from theoretical and experimental hadron spectra, leading to the color non-singlet spectroscopy., Comment: 65 pages, 6 figures
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- 2014
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3. Probing gluon dynamics by charm and bottom mesons in nuclear medium from heavy meson effective theory with 1/M-corrections
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Yasui, S. and Sudoh, K.
- Subjects
High Energy Physics - Phenomenology ,Nuclear Theory - Abstract
We consider heavy mesons with charm and bottom in nuclear medium. We construct the effective Lagrangian with axial-vector coupling including 1/M-corrections for the heavy meson mass $M$ by following the velocity-rearrangement invariance. As an application, we consider heavy mesons, $\bar{\mathrm{D}}$ and $\bar{\mathrm{D}}^{\ast}$ mesons for charm and $\mathrm{B}$ and $\mathrm{B}^{\ast}$ mesons for bottom, bound in nuclear matter, and we discuss their in-medium masses modified by the interaction with nucleons via pion exchanges including the 1/M-corrections. The mass modifications are affected by the gluon dynamics in nuclear medium. By comparison with the heavy quark effective theory, we find that the effects of scale anomaly become suppressed in nuclear medium. We also find that the contributions from the chromoelectric gluon are enhanced in nuclear medium, while those from the chromomagnetic gluon are reduced. We propose to use heavy mesons as probes to research the gluon fields in nuclear medium in experimental studies., Comment: 30 pages, 3 figures
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- 2013
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4. Spin degeneracy in multi-hadron systems with a heavy quark
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Yasui, S., Sudoh, K., Yamaguchi, Y., Ohkoda, S., Hosaka, A., and Hyodo, T.
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High Energy Physics - Phenomenology ,Nuclear Theory - Abstract
We study multi-hadron systems with a single heavy quark (charm or bottom) in the limit of heavy quark mass. The spin degeneracy of the states with quantum numbers $(j+1/2)^{P}$ and $(j-1/2)^{P}$ for $j \neq 0$, known in a normal hadron, can be generalized to multi-hadron systems. The spin degeneracy is the universal phenomena for any multi-hadron systems with a single heavy quark, irrespective of their internal structures, including compact multi-quarks, hadronic molecules and exotic nuclei. We demonstrate the spin degeneracy in the hadronic systems formed by a heavy hadron effective theory; $P^{(\ast)}N$ states with a $P^{(\ast)}=\bar{D}^{(\ast)}$, $B^{(\ast)}$ meson and a nucleon $N$, and a $P^{(\ast)}$ meson in nuclear matter., Comment: 9 pages, 1 figure
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- 2013
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5. Heavy quark dynamics for charm and bottom flavor on Fermi surface at zero temperature
- Author
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Yasui, S. and Sudoh, K.
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High Energy Physics - Phenomenology ,Nuclear Theory - Abstract
We discuss the dynamics in finite density medium including a heavy impurity particle (hadron or quark) with a heavy flavor, charm and bottom, at zero temperature. As a system, we consider a $\bar{D}$ ($B$) meson embedded in nuclear matter as a heavy impurity boson with SU(2) isospin symmetry. As another system, we also consider a charm (bottom) quark embedded in quark matter as a heavy impurity fermion with SU(3) color symmetry. We suppose a vector current interaction with SU($n$) symmetry ($n \ge 2$) for the fermion composing the Fermi surface and the embedded heavy impurity particle, and calculate the scattering amplitude perturbatively for the small coupling constant up to one-loop level. We obtain that the scattering amplitude has a logarithmic enhancement in the large mass limit of the heavy impurity particle, and show that the perturbative calculation breaks down for any small coupling constant in this limit., Comment: 25 pages, 2 figures
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- 2013
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6. Exotic mesons with hidden charm and bottom near thresholds
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Ohkoda, Shunsuke, Yamaguchi, Y., Yasui, S., Sudoh, K., and Hosaka, A.
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High Energy Physics - Phenomenology - Abstract
We study heavy hadron spectroscopy near heavy meson thresholds. We employ heavy pseudoscalar meson P and heavy vector meson P* as effective degrees of freedom and consider meson exchange potentials between them. All possible composite states which can be constructed from the P and P* mesons are studied up to the total angular momentum J <= 2. We consider, as exotic states, isosinglet states with exotic J^{PC} quantum numbers and isotriplet states. We solve numerically the Schr\"odinger equation with channel-couplings for each state. We found B(*)barB(*) molecule states for I^G(J^{PC}) = 1^+(1^{+-}) correspond to the masses of twin resonances Zb(10610) and Zb(10650). We predict several possible B(*)barB(*) bound and/or resonant states in other channels. On the other hand, there are no B(*)barB(*) bound and/or resonant states whose quantum numbers are exotic., Comment: 10 pages, 1 figure, to appear in the proceedings of The 5th International Workshop on Charm Physics (Charm 2012)
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- 2012
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7. $\bar{\mathrm{D}}$ and $\mathrm{B}$ mesons in nuclear medium
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Yasui, S. and Sudoh, K.
- Subjects
High Energy Physics - Phenomenology ,Nuclear Theory - Abstract
We discuss the mass modifications of $\bar{\mathrm{D}}$ and $\bar{\mathrm{D}}^{\ast}$ ($\mathrm{B}$ and $\mathrm{B}^{\ast}$) mesons in nuclear medium. The heavy quark symmetry for $\bar{\mathrm{D}}$ and $\bar{\mathrm{D}}^{\ast}$ ($\mathrm{B}$ and $\mathrm{B}^{\ast}$) mesons is adopted, and the interaction between a $\bar{\mathrm{D}}$ or $\bar{\mathrm{D}}^{\ast}$ ($\mathrm{B}$ or $\mathrm{B}^{\ast}$) meson and a nucleon is supplied from the pion exchange. We find the negative mass shifts for $\bar{\mathrm{D}}$ meson and $\mathrm{B}$ meson, and hence that the $\bar{\mathrm{D}}$ and $\mathrm{B}$ mesons are bound in the nuclear medium. As applications, we consider the atomic nuclei with a $\bar{\mathrm{D}}$ meson, $^{40}_{\bar{\mathrm{D}}}\mathrm{Ca}$ and $^{208}_{\bar{\mathrm{D}}}\mathrm{Pb}$, and investigate the energy levels of the $\bar{\mathrm{D}}$ meson in each nucleus. We also discuss the mass shifts in the isospin asymmetric nuclear medium, and present the possible phenomenon about distribution of isospin density around a $\bar{\mathrm{D}}$ or $\mathrm{B}$ meson in nuclear medium. We find that the mass shifts of $\bar{\mathrm{D}}^{\ast}$ and $\mathrm{B}^{\ast}$ mesons have large imaginary parts, which would prevent precise study of the energy levels of $\bar{\mathrm{D}}^{\ast}$ and $\mathrm{B}^{\ast}$ mesons in nuclei., Comment: 21 pages, 9 figures
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- 2012
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8. Heavy Ion Collisions at the LHC - Last Call for Predictions
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Abreu, S., Akkelin, S. V., Alam, J., Albacete, J. L., Andronic, A., Antonov, D., Arleo, F., Armesto, N., Arsene, I. C., Barnafoldi, G. G., Barrette, J., Bauchle, B., Becattini, F., Betz, B., Bleicher, M., Bluhm, M., Boer, D., Bopp, F. W., Braun-Munzinger, P., Bravina, L., Busza, W., Cacciari, M., Capella, A., Casalderrey-Solana, J., Chatterjee, R., Chen, L. -W., Cleymans, J., Cole, B. A., Del Valle, Z. Conesa, Csernai, L. P., Cunqueiro, L., Dainese, A., Ding, J. Dias de Deus H. -T., Djordjevic, M., Drescher, H., Dumitru, I. M. Dremin A., El, A., Engel, R., d'Enterria, D., Eskola, K. J., Fai, G., Ferreiro, E. G., Fries, R. J., Frodermann, E., Fujii, H., Gale, C., Gelis, F., Goncalves, V. P., Greco, V., Greiner, C., Gyulassy, M., van Hees, H., Heinz, U., Honkanen, H., Horowitz, W. A., Iancu, E., Ingelman, G., Jalilian-Marian, J., Jeon, S., Kaidalov, A. B., Kampfer, B., Kang, Z. -B., Karpenko, Iu. A., Kestin, G., Kharzeev, D., Ko, C. M., Koch, B., Kopeliovich, B., Kozlov, M., Kraus, I., Kuznetsova, I., Lee, S. H., Lednicky, R., Letessier, J., Levin, E., Li, B. -A., Lin, Z. -W., Liu, H., Liu, W., Loizides, C., Lokhtin, I. P., Machado, M. V. T., Malinina, L. V., Managadze, A. M., Mangano, M. L., Mannarelli, M., Manuel, C., Martinez, G., Milhano, J. G., Mocsy, A., Molnar, D., Nardi, M., Nayak, J. K., Niemi, H., Oeschler, H., Ollitrault, J. -Y., Paic, G., Pajares, C., Pantuev, V. S., Papp, G., Peressounko, D., Petreczky, P., Petrushanko, S. V., Piccinini, F., Pierog, T., Pirner, H. J., Porteboeuf, S., Potashnikova, I., Qin, G. Y., Qiu, J. -W., Rafelski, J., Rajagopal, K., Ranft, J., Rapp, R., Rasanen, S. S., Rathsman, J., Rau, P., Redlich, K., Renk, T., Rezaeian, A. H., Rischke, D., Roesler, S., Ruppert, J., Ruuskanen, P. V., Salgado, C. A., Sapeta, S., Sarcevic, I., Sarkar, S., Sarycheva, L. I., Schmidt, I., Shoshi, A. I., Sinha, B., Sinyukov, Yu. M., Snigirev, A. M., Srivastava, D. K., Stachel, J., Stasto, A., Stocker, H., Teplov, C. Yu., Thews, R. L., Torrieri, G., Pop, V. Topor, Triantafyllopoulos, D. N., Tuchin, K. L., Turbide, S., Tywoniuk, K., Utermann, A., Venugopalan, R., Vitev, I., Vogt, R., Wang, E., Wang, X. N., Werner, K., Wessels, E., Wheaton, S., Wicks, S., Wiedemann, U. A., Wolschin, G., Xiao, B. -W., Xu, Z., Yasui, S., Zabrodin, E., Zapp, K., Zhang, B., Zhang, B. -W., Zhang, H., and Zhou, D.
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Experiment ,Nuclear Experiment ,Nuclear Theory - Abstract
This writeup is a compilation of the predictions for the forthcoming Heavy Ion Program at the Large Hadron Collider, as presented at the CERN Theory Institute 'Heavy Ion Collisions at the LHC - Last Call for Predictions', held from May 14th to June 10th 2007., Comment: LaTeX, 185 pages, uses iop styles; writeup of the CERN Theory Institute 'Heavy Ion Collisions at the LHC - Last Call for Predictions', held from May 14th to June 10th 2007
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- 2007
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9. Triquark structure and isospin symmetry breaking in exotic Ds mesons
- Author
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Yasui, S. and Oka, M.
- Subjects
High Energy Physics - Phenomenology - Abstract
The color anti-triplet triquark $q\bar{q}\bar{q}$ is considered as a compact component in the tetraquark structure $cq\bar{q}\bar{q}$ of exotic $D_{s}$ mesons. We discuss the mass spectrum and the flavor mixing of the triquarks by using the instanton induced interaction and the one-gluon exchange potentials. As a characteristic property of the triquark, we investigate the isospin violation. It is shown that the flavor $\bar{\bf 3}$ (isosinglet) and $\bf 6$ (isotriplet) states may be strongly mixed and then are identified with $D_{s}(2632)$.
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- 2007
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10. Quark condensates in the chiral bag with the NJL interaction
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Yasui, S., Hosaka, A., and Oka, M.
- Subjects
High Energy Physics - Phenomenology - Abstract
We discuss the quark condensate of the vacuum inside the baryon. We analyze the 1+1 dimensional chiral bag in analogy with the realistic 3+1 dimensional one. The Nambu--Jona-Lasinio (NJL) type interaction is used to investigate the quark condensate in the chiral bag. Considering the strong meson-quark coupling, we solve the mean field solution to the scalar and pseudoscalar channels by including the chiral Casimir effects. The self-consistent equation allows a finite value of the quark condensate and hence a finite dynamical quark mass inside the bag. It is shown that an approximate Cheshire Cat picture holds for massive quarks.
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- 2006
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11. Chiral symmetry breaking and vacuum polarization in a bag
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Yasui, S.
- Subjects
High Energy Physics - Phenomenology - Abstract
We study the effects of a finite quark mass in the hedgehog configuration in the two phase chiral bag model. We discuss the chiral properties, such as the fractional baryon number and the chiral Casimir energy, by using the Debye expansion for the analytical calculation and the Strutinsky's smearing method for the numerical computation. It is shown that the fractional baryon number carried by massive quarks in the vacuum is canceled by that in the meson sector. A finite term of the chiral Casimir energy is obtained with subtraction of the logarithmic divergence term.
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- 2006
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12. Quark droplets with chiral symmetry in the Nambu--Jona-Lasinio model
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Yasui, S. and Hosaka, A.
- Subjects
High Energy Physics - Phenomenology - Abstract
We discuss the stability of strangelets by considering dynamical chiral symmetry breaking. For quark droplets of finite volume, we formulate the Nambu--Jona-Lasinio model with a basis set of the quark wave functions in the chiral bag model. Chiral symmetry breaking for the finite volume bag is discussed in a mean field approximation. Effects of the pion cloud including the chiral Casimir effect are investigated. Physical quantities of the quark droplets such as masses and radii are obtained for quark droplets of baryon numbers up to five. We also apply our model setting to the nucleon and discuss the stability of the quark droplets against nuclei.
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- 2006
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13. Chiral symmetry breaking and stability of quark droplets
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Yasui, S. and Hosaka, A.
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High Energy Physics - Phenomenology - Abstract
We discuss the stability of strangelets -- quark droplets with strangeness -- in the Nambu--Jona-Lasinio model supplemented by a boundary condition for quark confinement. Effects of dynamical chiral symmetry breaking are considered properly inside quark droplets of arbitrary baryon number. We obtain the energy per baryon number of quark droplets with baryon number from one to thousands. It is shown that strangelets are not the ground states as compared with nuclei, though they can be locally stable.
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- 2006
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14. Chiral symmetry breaking and stability of strangelets
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Yasui, S., Hosaka, A., and Toki, H.
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High Energy Physics - Phenomenology - Abstract
We discuss the stability of strangelets by considering dynamical chiral symmetry breaking and confinement. We use a $U(3)_{L} \times U(3)_{R}$ symmetric Nambu--Jona-Lasinio model for chiral symmetry breaking supplemented by a boundary condition for confinement. It is shown that strangelets with baryon number $A < 2 \times 10^{3}$ can stably exist. For the observables, we obtain the masses and the charge-to-baryon number ratios of the strangelets. These quantities are compared with the observed data of the exotic particles., Comment: 10 pages, 9 figures, submitted to Physical Review D
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- 2004
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15. Effects of quark matter and color superconductivity in compact stars
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Blaschke, D., Grigorian, H., Aguilera, D. N., Yasui, S., and Toki, H.
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High Energy Physics - Phenomenology - Abstract
The equation of state for quark matter is derived for a nonlocal, chiral quark model within the mean field approximation. We investigate the effects of a variation of the form factors of the interaction on the phase diagram of quark matter under the condition of beta-equilibrium and charge neutrality. Special emphasis is on the occurrence of a diquark condensate which signals a phase transition to color superconductivity and its effects on the equation of state. We calculate the quark star configurations by solving the Tolman- Oppenheimer- Volkoff equations and obtain for the transition from a hot, normal quark matter core of a protoneutron star to a cool diquark condensed one a release of binding energy of the order of Delta M c^2 ~ 10^{53} erg. We study the consequences of antineutrino trapping in hot quark matter for quark star configurations with possible diquark condensation and discuss the claim that this energy could serve as an engine for explosive phenomena. A "phase diagram" for rotating compact stars (angular velocity-baryon mass plane) is suggested as a heuristic tool for obtaining constraints on the equation of state of QCD at high densities. It has a critical line dividing hadronic from quark core stars which is correlated with a local maximum of the moment of inertia and can thus be subject to experimental verification by observation of the rotational behavior of accreting compact stars., Comment: 14 pages, 12 figures, Talk given at 2nd International Workshop on Hadron Physics: Effective Theories of Low-Energy QCD, Coimbra, Portugal, 25-29 Sep 2002
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- 2003
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16. Color superconductivity at finite density and temperature with flavor asymmetry
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Kiriyama, O., Yasui, S., and Toki, H.
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High Energy Physics - Phenomenology - Abstract
Color superconductivity of QCD at finite density, temperature and flavor asymmetry is studied within an approximation which the interaction is modeled upon four--fermion interactions. We calculate the thermodynamic potential in the so-called NJL-type model and study the phase structure at finite density, temperature and flavor asymmetry. We find that a mixed phase appears at sufficiently large flavor asymmetry and low temperature. A tricritical point in the $T$-$\mu_B$-$\mu_I$ plane is also found., Comment: 11pages, 7figures
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- 2001
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