arXiv subjects

Shun-ichi Kitahara

Publications and source records attributed to Shun-ichi Kitahara.

12 recordsLinked to original sources

arXiv2002

Gauge Problem of Monopole Dynamics in SU(2) Lattice Gauge Theory

Gauge problem of monopole dynamics is studied in SU(2) lattice gauge theory. We study first abelian and monopole contributions to the static potential in four smooth gauges, i.e., Laplacian Abelian (LA), Maximally Abelian Wilson Loop (MAWL) and L-type gauges in comparison with Maximally Abelian (MA) gauge. They all reproduce the string tension in good agreement with the SU(2) string tension. MA gauge is not the only choice of the good gauge which is suitable for the color confinement mechanism. Using an inverse Monte-Carlo method and the blockspin transformation, we determine effective monopole actions and the renormalization group (RG) flows of its coupling constants in various abelian projection schemes. Every RG flow looks to converge to a unique curve which suggests gauge independence in the infrared region.

hep-lat↗

arXiv1996

Critical exponents and abelian dominance in $SU(2)$ QCD

The critical properties of the abelian Polyakov loop and the Polyakov loop in terms of Dirac string are studied in finite temperature abelian projected $SU(2)$ QCD. We evaluate the critical point and the critical exponents from each Polyakov loop in the maximally abelian gauge using the finite-size scaling analysis. Abelian dominance in this case is proved quantitatively. The critical point of each abelian Polyakov loop is equal to that of the non-abelian Polyakov loop within the statistical errors. Also, the critical exponents are in good agreement with those from non-abelian Polyakov loops.

hep-lat↗

arXiv1996

Monopole action and monopole condensation in SU(3) lattice QCD

Effective monopole actions for various extended monopoles are derived from vacuum configurations after abelian projection in the maximally abelian gauge in $T=0$ and $T\ne 0$ $SU(3)$ lattice QCD. The actions obtained appear to be independent of the lattice volume adopted. At zero temperature, monopole condensation is seen to occur from energy-entropy balance in the strong coupling region. Larger $β$ is included in the monopole condensed phase as more extended monopoles are considered. The scaling seen in the $SU(2)$ case is not yet observed. The renormalization flow diagram suggests the existence of an infrared fixed point. A hysteresis behavior is seen around the critical temperature in the case of the $T\ne 0$ action.

hep-lat↗

arXiv1996

Critical exponents in abelian projected $SU(2)$ QCD

The critical properties of the abelian Polyakov loop and the Polyakov loop in terms of Dirac string are studied in finite temperature abelian projected $SU(2)$ QCD. The critical point and the critical exponents are determined from each Polyakov loop in the maximally abelian gauge using the finite-size scaling analyses. Those critical points and exponents are in good agreement with those from non-abelian Polyakov loops.

hep-lat↗

arXiv1996

Disorder Parameter of Confinement

The disorder parameter of confinement-deconfinement phase transition based on the monopole action determined previously in $SU(2)$ QCD are investigated. We construct an operator which corresponds to the order parameter defined in the abelian Higgs model. The operator shows proper behaviors as the disorder parameter in the numerical simulations of finite temperature QCD.

hep-lat↗

arXiv1996

Three topics of monopole dynamics in abelian projected QCD

Three topics about monopole dynamics after abelian projection are reported. The first is the new and detailed analyses of $SU(2)$ monopole action obtained after the block-spin transformation on the dual lattice. The $b=na(β)$ dependence for all couplings are well fitted with a universal curve. The distance dependence of the couplings is well reproduced by a massive propagator with the mass $m=0.8$ in unit of $b$. The second is the $SU(3)$ monopole action recently obtained. The third is new interesting gauges showing abelian and monopole dominances as in the maximally abelian gauge.

hep-lat↗

arXiv1995

Monopoles and hadron spectrum in quenched QCD

We report the preliminary results of the studies of hadron spectrum under the background of abelian and monopole gauge fields in quenched Wilson SU(3) QCD. Abelian gauge fields alone reproduce the same chiral limit as in the full case. Critical hopping parameter $κ_c$ and $m_ρ$ are the same in both cases. We need more time to get a definite result in the case of monopole background. The photon contribution do not produce any mass gap in the chiral limit ($κ=κ_c\sim 0.17$). The behavior is similar to those in the free photon case for $κ_c= 0.125$.

hep-lat↗

arXiv1995

Study of gauge (in)dependence of monopole dynamics

We investigated the gauge (in)dependence of the confinement mechanism due to monopole condensation in SU(2) lattice QCD by various abelian projections. We found (1) the string tension can be reproduced by monopoles alone also in Polyakov gauge and (2) the behaviors of the Polyakov loop at the critical temperature seem to be explained by the uniformity breaking of the monopole currents in every gauge.

hep-lat↗

arXiv1994

Monopoles and deconfinement transition in finite temperature $SU(2)$ QCD

We investigate the role of monopoles in the deconfinement transition of finite temperature $SU(2)$ QCD in the maximally abelian gauge. In the confinement phase a long monopole loop exists in each configuration, whereas no long loop exists in the deep deconfinement region. Balancing of the energy and the entropy of loops of the maximally extended monopoles can explain the occurrence of the deconfinement transition.

hep-lat↗

arXiv1994

String tension and monopoles in $T \neq 0$ SU(2) QCD

Monopole and photon contributions to abelian Wilson loops are calculated using Monte-Carlo simulations of finite-temperature $SU(2)$ QCD in the maximally abelian gauge. The string tension is reproduced by monopole contribution alone also in finite temperature SU(2) QCD. The spatial string tension scales as $\sqrtσ \propto g^{2}(T)T$ and is reproduced almost by monopole contribution alone. Each configuration has one long monopole loop, and the long monopole loops alone are responsible for the string tension in the confinement phase. On the other hand, the spatial string tension in the deconfinement phase is reproduced by wrapped monopole loops alone.

hep-lat↗

arXiv1994

Deconfinement transition and monopoles in $T\neq0$ $SU(2)$ QCD

The role of monopoles in the deconfinement transition is discussed in the framework of abelian projection in the maximally abelian gauge in $T\neq0$ $SU(2)$ QCD. Only one (or a few near $β_c$) long connected monopole loop exists uniformly through the whole lattice in each vacuum configuration in addition to some very short loops in the confinement phase and the long loop disappears in the deep deconfinement region. Energy-entropy balance of the long loops of maximally extended monopoles explains the existence of the deconfinement transition and reproduces roughly the value of the critical temperature.

hep-lat↗

arXiv1994

String tension and monopoles in $T \neq 0$ SU(2) QCD

Monopole and photon contributions to abelian Wilson loops are calculated using Monte-Carlo simulations of finite-temperature $SU(2)$ QCD in the maximally abelian gauge. Long monopole loops alone are responsible for the behavior of the string tension in the confinement phase up to the critical $β_c$. Short monopole loops and photons do not contribute to the string tension. The abelian and the monopole spacial string tensions (both of which agree with the normal ones for $β< β_c$) show a $g^{4}(T) T^2$ scaling behavior in the deconfinement phase. The abelian spacial string tension is in agreement with the full one even in the deconfinement phase.

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