351 research outputs found

    Low-lying Dirac eigenmodes and monopoles in 3+1D compact QED

    Full text link
    We study the properties of low-lying Dirac modes in quenched compact QED at β=1.01\beta =1.01, employing 123×Nt12^3\times N_t (Nt=4,6,8,10,12N_t =4,6,8,10,12) lattices and the overlap formalism for the fermion action. We pay attention to the spatial distributions of low-lying Dirac modes below and above the ``phase transition temperature'' TcT_c. Near-zero modes are found to have universal anti-correlations with monopole currents, and are found to lose their temporal structures above TcT_c exhibiting stronger spatial localization properties. We also study the nearest-neighbor level spacing distribution of Dirac eigenvalues and find a Wigner-Poisson transition.Comment: 10 pages, 10 figures, 1 tabl

    Role of Large Gluonic Excitation Energy for Narrow Width of Penta-Quark Baryons in QCD String Theory

    Full text link
    We study the narrow decay width of low-lying penta-quark baryons in the QCD string theoryin terms of gluonic excitations. In the QCD string theory, the penta-quark baryon decays via a gluonic-excited state of a baryon and meson system, where a pair of Y-shaped junction and anti-junction is created. Since lattice QCD shows that the lowest gluonic-excitation energy takes a large value of about 1 GeV, the decay of the penta-quark baryon near the threshold is considered as a quantum tunneling process via a highly-excited state (a gluonic-excited state) in the QCD string theory. This mechanism strongly suppresses the decay and leads to an extremely narrow decay width of the penta-quark system.Comment: Talk given at International Conference on the Structure of Baryons (Baryons 04) October 25 - 29, 2004, Ecole Polytechnique, Palaiseau, Franc

    Behind the success of the quark model

    Full text link
    The ground-state three-quark (3Q) potential V3Qg.s.V_{\rm 3Q}^{\rm g.s.} and the excited-state 3Q potential V3Qe.s.V_{\rm 3Q}^{\rm e.s.} are studied using SU(3) lattice QCD at the quenched level. For more than 300 patterns of the 3Q systems, the ground-state potential V3Qg.s.V_{\rm 3Q}^{\rm g.s.} is investigated in detail in lattice QCD with 123×2412^3\times 24 at β=5.7\beta=5.7 and with 163×3216^3\times 32 at β=5.8,6.0\beta=5.8, 6.0. As a result, the ground-state potential V3Qg.s.V_{\rm 3Q}^{\rm g.s.} is found to be well described with Y-ansatz within the 1%-level deviation. From the comparison with the Q-Qˉ\rm\bar Q potential, we find the universality of the string tension as σ3QσQQˉ\sigma_{\rm 3Q}\simeq\sigma_{\rm Q\bar Q} and the one-gluon-exchange result as A3Q12AQQˉA_{\rm 3Q}\simeq\frac12 A_{\rm Q\bar Q}. The excited-state potential V3Qe.s.V_{\rm 3Q}^{\rm e.s.} is also studied in lattice QCD with 163×3216^3\times 32 at β=5.8\beta=5.8 for 24 patterns of the 3Q systems.The energy gap between V3Qg.s.V_{\rm 3Q}^{\rm g.s.} and V3Qe.s.V_{\rm 3Q}^{\rm e.s.}, which physically means the gluonic excitation energy, is found to be about 1GeV in the typical hadronic scale, which is relatively large compared with the excitation energy of the quark origin. This large gluonic excitation energy justifies the great success of the simple quark model.Comment: Talk given at 16th International Conference on Particles and Nuclei (PANIC 02), Osaka, Japan, 30 Sep - 4 Oct 200

    Lattice QCD Study for the Interquark Force in Three-Quark and Multi-Quark Systems

    Full text link
    We study the three-quark and multi-quark potentials in SU(3) lattice QCD. From the accurate calculation for more than 300 different patterns of 3Q systems, the static ground-state 3Q potential V3Qg.s.V_{\rm 3Q}^{\rm g.s.} is found to be well described by the Coulomb plus Y-type linear potential (Y-Ansatz) within 1%-level deviation. As a clear evidence for Y-Ansatz, Y-type flux-tube formation is actually observed on the lattice in maximally-Abelian projected QCD. For about 100 patterns of 3Q systems, we perform the accurate calculation for the 1st excited-state 3Q potential V3Qe.s.V_{\rm 3Q}^{\rm e.s.} by diagonalizing the QCD Hamiltonian in the presence of three quarks, and find a large gluonic-excitation energy ΔE3QV3Qe.s.V3Qg.s.\Delta E_{\rm 3Q} \equiv V_{\rm 3Q}^{\rm e.s.}-V_{\rm 3Q}^{\rm g.s.} of about 1 GeV, which gives a physical reason of the success of the quark model. ΔE3Q\Delta E_{\rm 3Q} is found to be reproduced by the ``inverse Mercedes Ansatz'', which indicates a complicated bulk excitation for the gluonic-excitation mode. We study also the tetra-quark and the penta-quark potentials in lattice QCD, and find that they are well described by the OGE Coulomb plus multi-Y type linear potential, which supports the flux-tube picture even for the multi-quarks. Finally, the narrow decay width of penta-quark baryons is discussed in terms of the QCD string theory.Comment: Invited talk at Int. Conference on Quark Confinement and the Hadron Spectrum 6, Sardinia, Italy, 21-25 Sep 200

    On the center-vortex baryonic area law

    Full text link
    We correct an unfortunate error in an earlier work of the author, and show that in center-vortex QCD (gauge group SU(3)) the baryonic area law is the so-called YY law, described by a minimal area with three surfaces spanning the three quark world lines and meeting at a central Steiner line joining the two common meeting points of the world lines. (The earlier claim was that this area law was a so-called Δ\Delta law, involving three extremal areas spanning the three pairs of quark world lines.) We give a preliminary discussion of the extension of these results to SU(N),N>3SU(N), N>3. These results are based on the (correct) baryonic Stokes' theorem given in the earlier work claiming a Δ\Delta law. The YY-form area law for SU(3) is in agreement with the most recent lattice calculations.Comment: 5 pages, RevTeX4, 5 .eps figure

    Runaway Dynamics and Supersymmetry Breaking

    Full text link
    Supersymmetric SU(N_C) gauge theories possess runaway-type superpotentials for N_F < N_C, where N_F is the flavor number of massless quarks. We show that the runaway behavior can be stabilized for N_F nearly equal to N_C by introducing singlets with the aid of perturbative corrections to the Kahler potential, generating (local) minima of supersymmetry breaking.Comment: 6 page

    Effective field theories for baryons with two- and three-heavy quarks

    Full text link
    Baryons made of two or three heavy quarks can be described in the modern language of non-relativistic effective field theories. These, besides allowing a rigorous treatment of the systems, provide new insight in the nature of the three-body interaction in QCD.Comment: 7 pages, 1 figure; published versio

    Low-lying spectrum of the Y-string three-quark potential using hyper-spherical coordinates

    Full text link
    We calculate the energies of three-quark states with definite permutation symmetry (i.e. of SU(6) multiplets) in the N=0,1,2 shells, confined by the Y-string three-quark potential. The exact Y-string potential consists of one, so-called three-string term, and three angle-dependent two-string terms. Due to this technical complication we treat the problem at three increasingly accurate levels of approximation: 1) the (approximate) three-string potential expanded to first order in trigonometric functions of hyper-spherical angles; 2) the (approximate) three-string potential to all orders in the power expansion in hyper-spherical harmonics, but without taking into account the transition(s) to two-string potentials; 3) the exact minimal-length string potential to all orders in power expansion in hyper-spherical harmonics, and taking into account the transition(s) to two-string potentials. We show the general trend of improvement %convergence of these approximations: The exact non-perturbative corrections to the total energy are of the order of one per cent, as compared with approximation 2), yet the exact energy differences between the [20,1+],[70,2+],[56,2+],[70,0+][20,1^{+}], [70,2^{+}], [56,2^{+}], [70,0^{+}]-plets are shifted to 2:2:0.9, from the Bowler and Tynemouth separation rule 2:2:1, which is obeyed by approximation 2) at the one per cent level. The precise value of the energy separation of the first radial excitation ("Roper") [56,0+][56^{\prime},0^{+}]-plet from the [70,1][70,1^{-}]-plet depends on the approximation, but does not become negative, i.e. the "Roper" remains heavier than the odd-parity [70,1][70,1^{-}]-plet in all of our approximations.Comment: 19 pages, 6 figure

    A Silicon Model Of Auditory Localization

    Full text link

    Gamma rays and positrons from a decaying hidden gauge boson

    Get PDF
    We study a scenario that a hidden gauge boson constitutes the dominant component of dark matter and decays into the standard model particles through a gauge kinetic mixing. Interestingly, gamma rays and positrons produced from the decay of hidden gauge boson can explain both the EGRET excess of diffuse gamma rays and the HEAT anomaly in the positron fraction. The spectra of the gamma rays and the positrons have distinctive features; the absence of line emission of the gamma ray and a sharp peak in the positron fraction. Such features may be observed by the GLAST and PAMELA satellites.Comment: 16 pages, 4 figures, adding PAMELA data, the version accepted by PL