G. Ossola

Considerations concerning the contributionsof fundamental particles to the vacuum energy density

Abstract.The covariant regularization of the contributions of fundamental particles to the vacuum energy density is implemented in the Pauli-Villars, dimensional regularization, and Feynman regulator frameworks. Rules of correspondence between dimensional regularization and cutoff calculations are discussed. Invoking the scale invariance of free field theories in the massless limit, as well as consistency with the rules of correspondence, it is argued that quartic divergences are absent in the case of free fields, while it is shown that they arise when interactions are present.

Dynamic critical behavior of the Swendsen-Wang algorithm for the three-dimensional Ising model

We have performed a high-precision Monte Carlo study of the dynamic critical behavior of the Swendsen-Wang algorithm for the three-dimensional Ising model at the critical point. For the dynamic critical exponents associated to the integrated autocorrelation times of the energy-like observables, we find z(int,N) = z(int,epsilon) = z(int,epsilon)= 0.459 +/- 0.005 +/- 0.025, where the first error bar represents statistical error (68% confidence interval) and the second error bar represents possible systematic error due to corrections to scaling (68% subjective confidence interval). For the susceptibility-like observables, we find z(int,M2) = z(int,S2) = 0.443 +/- 0.005 +/- 0.030. For the dynamic critical exponent associated to the exponential autocorrelation time, we find z(exp) approximate to 0.481. Our data are consistent with the Coddington-Baillie conjecture z(SW) = beta/v approximate to 0.5183, especially if it is interpreted as referring to z(exp)

Considerations concerning the radiative corrections to muon decay in the Fermi and standard theories

The FAC, PMS, and BLM optimization methods are applied to the QED corrections to the muon lifetime in the Fermi V-A theory. The FAC and PMS scales are close to me, while the BLM scale nearly coincides with the geometric average √memμ. The optimized expressions are employed to estimate the third order coefficient in the α(mμ) expansion and the theoretical error of the perturbative series. Using arguments based on effective field theory and a simple examination of Feynman diagrams, it is shown that, if contributions of O(αmμ2/MW2) are neglected, the corrections to muon decay in the SM factorize into the QED correction of the Fermi V-A theory and the electroweak amplitude g2/(1 − Δr), both of which are strictly scale-independent. We use the results to clarify how the QED corrections to muon decay and the Fermi constant GF should be used in the SM, and what is the natural choice of scales if running couplings are employed.

Scale-independent calculation of sin2θefflept

Abstract We present a calculation of the electroweak mixing parameter sin2θefflept that incorporates known higher order effects, shares the desirable convergence properties of the MS scheme, and has the important theoretical advantage of being strictly independent of the electroweak scale in finite orders of perturbation theory. We also show how this formulation can be extended to the calculation of the W mass MW. The results provide accurate, scale-independent evaluations of these important parameters, as functions of the Higgs boson mass MH, and are compared with previous calculations in order to analyze the scheme and scale dependence of the electroweak corrections.

Systematic errors due to linear congruential random-number generators with the Swendsen-Wang algorithm: A warning

We show that linear congruential pseudo-random-number generators can cause systematic errors in Monte Carlo simulations using the Swendsen-Wang algorithm, if the lattice size is a multiple of a very large power of 2 and one random number is used per bond. These systematic errors arise from correlations within a single bond-update half-sweep. The errors can be eliminated (or at least radically reduced) by updating the bonds in a random order or in an aperiodic manner. It also helps to use a generator of large modulus (e.g., 60 or more bits).

The electroweak form factor \(\hat{\kappa}(q^2)\) and the running of \(\sin^2\hat{\theta}_{\mathrm {W}}\)

Abstract.Gauge independent form factors

Bounds on M W , M t , \(\sin^2 \theta_{\mathrm{{eff}}}^{\mathrm{{lept}}}\)

rho^{(e ; e)}

Bounds on M(W), M(t), sin**2 Theta(eff)lept

and

Novel approach to renormalize the electroweak sector of the standard model

hat{kappa}^{(e ; e)}(q^2)

Bounds on the Higgs boson mass from M(W)

for Møller scattering at