Implications of High Precision Experiments and the CDF Top Quark Candidates
| dc.creator | Erler, Jens | |
| dc.creator | Langacker, Paul | |
| dc.date | 1994-11-01 | |
| dc.date.accessioned | 2026-07-07T10:35:07Z | |
| dc.date.available | 2026-07-07T10:35:07Z | |
| dc.description | We discuss the consequences of recent experimental results from CDF, SLC, LEP and elsewhere for the Standard Model and for new physics. A global fit to all indirect precision data yields $m_t = 175 \pm 11^{+17}_{-19}$~GeV, $\sin^2θ_{MS} = 0.2317(3)(2)$, and $α_s = 0.127(5)(2)$, where the central values are for $M_H = 300$ GeV and the second uncertainties are for $M_H \rightarrow 1000$ GeV (+) and 60 GeV (-). The $m_t$ value is in remarkable agreement with the value $m_t=174 \pm 16$ GeV suggested by the CDF candidate events. There is a slight preference for a light Higgs with $M_H < 730$ (880) GeV at 95\% c.l. if the CDF $m_t$ value is (not) included. The sensitivity is, however, due almost entirely to the anomalously large observed values for the $Z \rightarrow b\bar{b}$ width and left-right asymmetry. The value of alpha_s (from the lineshape) is clean theoretically assuming the Standard Model, but is sensitive to the presence of new physics contributions to the $Z \rightarrow b\bar{b}$ vertex. Allowing a vertex correction $δ_{b\bar{b}}^{\rm new}$ one obtains the significantly lower value alpha_s = 0.111 \pm 0.009, in better agreement with low energy determinations, and $δ_{b\bar{b}}^{\rm new} = 0.023 \pm 0.011$. There is now enough data to perform more general fits to parameters describing new physics effects and to separate these from $m_t$ and $M_H$. Allowing the parameter $ρ_0$, which describes sources of $SU(2)$ breaking beyond the Standard Model, to be free one finds $ρ_0=1.0012 \pm 0.0017 \pm 0.0017$, remarkably close to unity. One can also separate the new physics contributions to the oblique parameters $S_{\rm new}$, $T_{\rm new}$ and $U_{\rm new}$, which all take values consistent with zero. The effects of supersymmetry on the determination of the SM parameters are discussed. | |
| dc.description | 23 pages REVTeX + 3 figures (not included); complete postscript file available via anonymous ftp ftp://dept.physics.upenn.edu/pub/Langacker/statussmprep.ps | |
| dc.identifier | https://arxiv.org/abs/hep-ph/9411203 | |
| dc.identifier | http://arxiv.org/abs/hep-ph/9411203 | |
| dc.identifier | Phys.Rev.D52:441-450,1995 | |
| dc.identifier | doi:10.1103/PhysRevD.52.441 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/179655 | |
| dc.subject | High Energy Physics - Phenomenology | |
| dc.title | Implications of High Precision Experiments and the CDF Top Quark Candidates | |
| dc.type | text |