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Search Results: 1 - 10 of 5010 matches for " Chulwoo Jung "
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Relating U(1) monopole configurations to SU(2) saddle-point configurations
Chulwoo Jung
Physics , 1996, DOI: 10.1016/S0920-5632(96)00699-8
Abstract: We have studied field configurations of the 3-dimensional Georgi-Glashow model which interpolate between the $U(1)$ and the $SU(2)$ limits. In the intermediate region, these configurations contain 't-Hooft--Polyakov monopoles. We use cooling and extremization to find these configurations and investigate their evolution as we adiabatically move towards the $U(1)$ and the $SU(2)$ limits. We also evolve an $SU(2)$ saddle point solution towards the $U(1)$ limit to see the relation between the unstable solutions in the $SU(2)$ theory and the stable ones in the $U(1)$ theory.
Thermodynamics using p4-improved staggered fermion action on QCDOC
Chulwoo Jung
Physics , 2005,
Abstract: We present an exploratory study of the thermodynamics of $N_f=3$ QCD with an improved staggered fermions using the QCDOC supercomputer. We use a p4 action with MILC-style smeared links (Fat 7). Some details of the implementation of the p4 action on QCDOC are discussed and performance benchmarks are given. We show preliminary results for the quark mass dependence of the pseudo-critical temperature $T_c$ from several lattice volumes . We also make a comparison between p4fat7 and the old p4 action.
Status of dynamical ensemble generation
Chulwoo Jung
Physics , 2010,
Abstract: I give an overview of current and future plans of dynamical QCD ensemble generation activities. A comparison of simulation cost between different discretizations is made. Recent developments in techniques and algorithms used in QCD dynamical simulations, especially mass reweighting, are also discussed.
Analysis of saddle-point configurations in 3-dimensional SU(2) gauge theory
Chulwoo Jung
Physics , 1995, DOI: 10.1016/0920-5632(96)00063-1
Abstract: We discuss the properties of a class of saddle point solutions in SU(2) in three dimensions (SU$(2)_3$), exhibiting localized peaks in the action. These configurations are generated by deterministic cooling and extremizing algorithms from analytic configurations. They share some characteristics with cooled and extremized Monte Carlo generated lattices. We have investigated physical behavior such as the string tension by averaging over this class of saddle point configurations. We have also measured the eigenvalues for harmonic fluctuations around these configurations.
Monopole-antimonopole condensation in the interpolating Georgi-Glashow model
Chulwoo Jung
Physics , 1997, DOI: 10.1016/S0920-5632(97)00812-8
Abstract: We study the three dimensional Georgi-Glashow model (which interpolates smoothly between pure U(1) and SU(2) limits) using a constrained cooling which preserves 't Hooft-Polyakov monopoles. We find that the monopole-antimonopole condensation gives an area law for the Wilson loops. The monopole contribution to the string tension is close to the Monte Carlo value in the intermediate region.
Photon Structure Functions from Quenched Lattice QCD
Xiangdong Ji,Chulwoo Jung
Physics , 2001, DOI: 10.1103/PhysRevD.64.034506
Abstract: We calculate the first moment of the photon structure function, $^{\gamma}=\int^1_0 dx F^{\gamma}_2(x,Q^2)$, on the quenched lattices with $\beta=6.0$ using the formalism developed by the authors recently. In this exploratory study, we take into account only the connected contractions. The result is compared with the experimental data as well as model predictions.
Studying Hadronic Structure of the Photon in Lattice QCD
Xiangdong Ji,Chulwoo Jung
Physics , 2001, DOI: 10.1103/PhysRevLett.86.208
Abstract: We show that the matrix element of a local quark-gluon operator in the photon state, $<\gamma(k\lambda)|\hat O| \gamma(k\lambda)>$, can be calculated in lattice QCD. The result is generalized to other quantities involving space-like photons, including the transition form factor $\gamma\gamma^*\to \pi^0$ and the virtual-photon-nucleon Compton amplitude $<\gamma^*N |\gamma^*N>$ which can be used to define the generalized Drell-Hearn-Gerasimov and Bjorken sum rules.
Status of 2+1 flavor, 32^3x64 domain wall fermion simulations
Chulwoo Jung,for RBC,UKQCD collaborations
Physics , 2007,
Abstract: We describe details of 1/a ~ 2.2Gev, L ~ 3 fm dynamical domain wall fermion simulations which will allow us to do a more systematic continuum extrapolation in combination with existing simu- lations. Details of the simulations such as algorithm choices and machine performance, as well as results of basic measurements are presented. These configurations are presently being generated on the QCDOC machine at Edinburgh and the DOE QCDOC machine at Brookhaven as part of a joint project with LHPC.
Domain-Wall Induced Quark Masses in Topologically-Nontrivial Background
Valeriya Gadiyak,Xiangdong Ji,Chulwoo Jung
Physics , 2000, DOI: 10.1103/PhysRevD.62.074508
Abstract: In the domain-wall formulation of chiral fermion, the finite separation between domain-walls ($L_s$) induces an effective quark mass ($m_{\rm eff}$) which complicates the chiral limit. In this work, we study the size of the effective mass as the function of $L_s$ and the domain-wall height $m_0$ by calculating the smallest eigenvalue of the hermitian domain-wall Dirac operator in the topologically-nontrivial background fields. We find that, just like in the free case, $m_{\rm eff}$ decreases exponentially in $L_s$ with a rate depending on $m_0$. However, quantum fluctuations amplify the wall effects significantly. Our numerical result is consistent with a previous study of the effective mass from the Gell-Mann-Oakes-Renner relation.
A Lattice Study of the Magnetic Moment and the Spin Structure of the Nucleon
Valeriya Gadiyak,Xiangdong Ji,Chulwoo Jung
Physics , 2001, DOI: 10.1103/PhysRevD.65.094510
Abstract: Using an approach free from momentum extrapolation, we calculate the nucleon magnetic moment and the fraction of the nucleon spin carried by the quark angular momentum in the quenched lattice QCD approximation. Quarks with three values of lattice masses, 210, 124 and 80 MeV, are formulated on the lattice using the standard Wilson approach. At every mass, 100 gluon configurations on 16^3 x 32 lattice with \beta=6.0 are used for statistical averaging. The results are compared with the previous calculations with momentum extrapolation. The contribution of the disconnected diagrams is studied at the largest quark mass using noise theory technique.
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