Physics – High Energy Physics – High Energy Physics - Phenomenology
Scientific paper
1996-01-08
Prog.Theor.Phys.Suppl.123:173-194,1996
Physics
High Energy Physics
High Energy Physics - Phenomenology
Talk presented at Yukawa International Seminar (YKIS)~'95, 23 pages, uuencoded compressed tar file of LaTeX file and 13 EPS fi
Scientific paper
10.1143/PTPS.123.173
The most important hint of physics beyond the Standard Model (SM) from the 1995 precision electroweak data is that the most precisely measured quantities, the total, leptonic and hadronic decay widths of the $Z$ and the effective weak mixing angle, $\sin^2\theta_W$, measured at LEP and SLC, and the quark-lepton universality of the weak charged currents measured at low energies, all agree with the predictions of the SM at a few $\times 10^{-3}$ level. By taking into account the above constraints I examine implications of three possible disagreements between experiments and the SM predictions. It is difficult to interpret the 11\% (2.5-$\sigma$) deficit of the $Z$-partial-width ratio $R_c=\Gamma_c/\Gamma_h$, since it either implies an unacceptably large $\alpha_s$ or a subtle cancellation among hadronic $Z$ decay widths in order to keep all the other successful predictions of the SM. The 2\% (3-$\sigma$) excess of the ratio $R_b=\Gamma_b/\Gamma_h$ may indicate the presence of a new rather strong interaction, such as the top-quark Yukawa coupling in the supersymmetric (SUSY) SM or a new interaction responsible for the large top-quark mass in the Technicolor scenario of dynamical electroweak symmetry breaking. Another interpretation may be additional tree-level gauge interactions that couple only to the third generation of fermions. A common consequence of these attempts is a rather small $\alpha_s$, $\alpha_s(\mz )_{\msbar}=0.104\pm 0.08$. The 0.17\% (1-$\sigma$) deficit ...
No associations
LandOfFree
Looking Beyond the Standard Model through Precision Electroweak Physics does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Looking Beyond the Standard Model through Precision Electroweak Physics, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Looking Beyond the Standard Model through Precision Electroweak Physics will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-703420