Measurement of Trilinear Gauge Couplings in e+e−e^+ e^- Collisions at 161 GeV and 172 GeV

Trilinear gauge boson couplings are measured using data taken by DELPHI at 161~GeV and 172~GeV. Values for $WWV$ couplings ($V=Z, \gamma$) are determined from a study of the reactions \eeWW\ and \eeWev, using differential distributions from the $WW$ final state in which one $W$ decays hadronically and the other leptonically, and total cross-section data from other channels. Limits are also derived on neutral $ZV\gamma$ couplings from an analysis of the reaction \eegi

A Precise measurement of the partial decay width ratio R(b)**0 = Gamma(b anti-b) / Gamma(had)

The partial decay width of the Z to b (b) over bar quark pairs has been measured by the DELPHI detector at LEP using data taken in the years 1992 to 1995. Decays of b-hadrons were tagged by several methods using tracks with large impact parameters and/or reconstructed secondary vertices; complemented by event shape variables. Combining these methods in a multivariate analysis the value Gamma(Z --> b (b) over bar)/Gamma(Z --> had) = 0.21634 +/- 0.00067(stat) +/- 0.00060(syst) was obtained, where the c (c) over bar production fraction was fixed to its Standard Model value. RI De Angelis, Alessandro/B-5372-2009; Ragazzi, Stefano/D-2463-2009; Gonzalez Caballero, Isidro/E-7354-2010; Krammer, Manfred/A-6508-2010; Muresan, Raluca-Anca/C-3725-2011; Katsanevas, Stavros/A-4297-2011; Ruiz, Alberto/E-4473-2011; Marti-Garcia, Salvador/F-3085-2011; Verzi, Valerio/B-1149-2012; branchini, paolo/A-4857-2011; Shellard, Ronald/G-4825-2012; Monge, Maria Roberta/G-9127-2012; Petrolini, Alessandro/H-3782-2011; Fruhwirth, Rudolf/H-2529-201

Search for Leptoquarks and FCNC in e(+)(e)(-) annihilations root s = 183 GeV

A search fur events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector. These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 pb(-1) Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from 134GcV/c(2) to 171GeV/c(2) for electromagnetic type couplings) and couplings of the leptoquark rates. A search for top-charm flavour changing neutral currents (e(+)e(-) --> (t) over bar c or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95%: confidence level). (C) 1999 Elsevier Science B.V. All rights reserved. RI De Angelis, Alessandro/B-5372-2009; Gonzalez Caballero, Isidro/E-7354-2010; Krammer, Manfred/A-6508-2010; Muresan, Raluca-Anca/C-3725-2011; Katsanevas, Stavros/A-4297-2011; Peralta, Luis/C-8369-2011; Ruiz, Alberto/E-4473-2011; Marti-Garcia, Salvador/F-3085-2011; Verzi, Valerio/B-1149-2012; branchini, paolo/A-4857-2011; Shellard, Ronald/G-4825-2012; Petrolini, Alessandro/H-3782-2011; Fruhwirth, Rudolf/H-2529-2012; Monge, Maria Roberta/G-9127-201

Measurement of A(FB)(b(b)over-bar) in hadronic Z decays using a jet charge technique

The bb forward-backward asymmetry has been determined from the average charge how measured in a sample of 3,500,000 hadronic Z decays collected with the DELPHI detector in 1992 - 1995. The measurement is performed in an enriched b (b) over bar sample selected using an impact parameter tag and results in the following values for the bl; forward-backward asymmetry: A(FB)(b (b) over bar) (89.55 GeV) = 0.068 +/- 0.016 (stat.) +/- 0.0013(syst.) A(FB)(b (b) over bar)(91.26 GeV) = 0.0982 +/- 0.0047(stat.) +/- 0.0016(syst.) A(FB)(b (b) over bar)(92.94 GeV) = 0.123 +/- 0.016 (stat.) +/- 0.0027(syst.) The b (b) over bar charge separation required for this analysis is directly measured in the b tagged sample, while the other charge separations are obtained from a fragmentation model precisely calibrated to data. The effective weak mixing angle is deduced from the measurement to be: sin(2)theta(eff)1 = 0.23186 +/- 0.00063