Critical behavior of Ginzburg-Landau model coupled to massless Dirac fermions

We point out interesting effects of additional massless Dirac fermions with N_F colors upon the critical behavior of the Ginzburg-Landau model. For increasing N_F, the model is driven into the type II regime of superconductivity. The critical exponents are given as a function of N_F.Comment: RevTex4, 4 pages, 1 figure; author information and latest update to this paper at http://www.physik.fu-berlin.de/~kleinert/institution.html; version 2: new references and comments on chiral symmetry breaking adde

Three-Loop Electroweak Correction to the Rho Parameter in the Large Higgs Mass Limit

We present an analytical calculation of the leading three-loop radiative correction to the rho-parameter in the Standard Model in the large Higgs mass limit. This correction, of order g^6 m_H^4/M_W^4, is opposite in sign to the leading two-loop correction of order g^4 m_H^2/M_W^2. The two corrections cancel each other for a Higgs mass of approximately 480 GeV. The result shows that it is extremely unlikely that a strongly interacting Higgs sector could fit the data of electroweak precision measurements.Comment: 15 pages, late

Three-loop electroweak corrections to the W-boson mass and sin^2 theta_eff in the large Higgs mass limit

We present an analytical calculation of the leading three-loop radiative correction to the S-parameter in the Standard Model in the large Higgs mass limit. Numerically, S^(3) = 1.1105*g^4/(1024 pi^3)*m_H^4/M_W^4. When combined with the corresponding three-loop correction to the rho-parameter, this leads to shifts of Delta^(3) sin^2 theta_eff = 4.6*10^-9*m_H^4/M_W^4 in the effective weak mixing angle and Delta^(3) M_W = -6.3*10^-4*MeV*m_H^4/M_W^4 in the W boson mass. For both of these observables, the sign of the three-loop correction is equal to that of the one-loop correction.Comment: 12 pages, two Figure

Hamiltonian Study of Improved U(1U(1 Lattice Gauge Theory in Three Dimensions

A comprehensive analysis of the Symanzik improved anisotropic three-dimensional U(1) lattice gauge theory in the Hamiltonian limit is made. Monte Carlo techniques are used to obtain numerical results for the static potential, ratio of the renormalized and bare anisotropies, the string tension, lowest glueball masses and the mass ratio. Evidence that rotational symmetry is established more accurately for the Symanzik improved anisotropic action is presented. The discretization errors in the static potential and the renormalization of the bare anisotropy are found to be only a few percent compared to errors of about 20-25% for the unimproved gauge action. Evidence of scaling in the string tension, antisymmetric mass gap and the mass ratio is observed in the weak coupling region and the behaviour is tested against analytic and numerical results obtained in various other Hamiltonian studies of the theory. We find that more accurate determination of the scaling coefficients of the string tension and the antisymmetric mass gap has been achieved, and the agreement with various other Hamiltonian studies of the theory is excellent. The improved action is found to give faster convergence to the continuum limit. Very clear evidence is obtained that in the continuum limit the glueball ratio $M_{S}/M_{A}$ approaches exactly 2, as expected in a theory of free, massive bosons.Comment: 13 pages, 15 figures, submitted to Phys. Rev.