120,793 research outputs found
BES Recent Results and Future Plans
We report the preliminary R values for all the 85 energy points scanned in
the energy region of 2-5 GeV with the upgraded Beijing Spectrometer (BESII) at
Beijing Electron Positron Collider (BEPC). Preliminary results from the J/psi
data collected with both BESI and BESII are presented. Measurements of the
branching fraction of the psi(2S) decays and the psi(2S) resonance parameters
are reported. The future plans, i.e. significantly upgrade the machine and
detector are also discussed.Comment: Talk given at APPAC2000, 6 pages, 8 figure
Renormalization Scheme Ambiguities in the Models with More than One Coupling
The process of renormalization to eliminate divergences arising in quantum
field theory is not uniquely defined; one can always perform a finite
renormalization, rendering finite perturbative results ambiguous. The
consequences of making such finite renormalizations have been examined in the
case of there being one or two couplings. In this paper we consider how finite
renormalizations can affect more general models in which there are more than
two couplings. In particular, we consider the Standard Model in which there are
essentially five couplings. We show that in this model (when neglecting all
mass parameters) if we use mass independent renormalization, then the
renormalization group beta-functions are not unique beyond one loop order, that
it is not in general possible to eliminate all terms beyond certain order for
all these beta-functions, but that for a physical process all contributions
beyond one loop order can be subsumed into the beta-functions
- …