Measurement of → τ and a new limit for → τ

Abstract

Using a data sample of 1475 000 Z-f q4(y) events collected during 1994 with the L3 detector at LEP, we have studied the purely leptonic decays of heavy flavour mesons, D;

Measurement ofB(Ds+→l+ν)and the decay constantfAlexander1, Cassel2, Duboscq3 et al. 2009Phys. Rev. D786330View full textAdd to dashboardCite

“…[21] µ + ν (6.38 ± 0.76 ± 0.52) · 10 −3 274 ± 16 ± 12 Average of CLEO and Belle results above, radiatively corrected 261.2 ± 6.9 CLEO [14] µ + ν (6.2 ± 0.8 ± 1.3 ± 1.6) · 10 −3 3.6±0.9 273 ± 19 ± 27 ± 33 BEATRICE [15] µ + ν (8.3 ± 2.3 ± 0.6 ± 2.1) · 10 −3 3.6±0.9 312 ± 43 ± 12 ± 39 ALEPH [16] µ + ν (6.8 ± 1.1 ± 1.8) · 10 −3 3.6±0.9 282 ± 19 ± 40 ALEPH [16] τ + ν (5.8 ± 0.8 ± 1.8) · 10 −2 L3 [17] τ + ν (7.4 ± 2.8 ± 1.6 ± 1.8) · 10 −2 299 ± 57 ± 32 ± 37 OPAL [18] τ + ν (7.0 ± 2.1 ± 2.0) · 10 −2 283 ± 44 ± 41 BaBar [19] µ + ν (6.74 ± 0.83 ± 0. [6] 241 ± 3 208 ± 4 1.162 ± 0.009 Lattice (FNAL+MILC+HPQCD) [5] 249 ± 3 ± 16 201 ± 3 ± 17 1.24 ± 0.01 ± 0.07 QL (QCDSF) [37] 220 ± 6 ± 5 ± 11 206 ± 6 ± 3 ± 22 1.07 ± 0.02 ± 0.02 QL (Taiwan) [38] 266 ± 10 ± 18 235 ± 8 ± 14 1.13 ± 0.03 ± 0.05 QL (UKQCD) [39] 236 ± 8 1.10 ± 0.02 QCD Sum Rules [41] 205 ± 22 177 ± 21 1.16 ± 0.01 ± 0.03 QCD Sum Rules [42] 235 ± 24 203 ± 20 1.15 ± 0.04 Field Correlators [43] 210 ± 10 260 ± 10 1.24 ± 0.03 Quark Model [44] 268 234 1.15 Quark Model [45] 248±27 230±25 1.08±0.01 LFQM (Linear) [46] 211 248 1.18 LFQM (HO) [46] 194 233 1.20 LF-QCD [47] 253 241 1.05 Potential Model [48] 241 238 1.01 Isospin Splittings [49] 262 ± 29 on f D + and f Ds of 230 and 270 MeV, respectively, have been determined using two-point correlation functions by Khodjamirian [36].…”

“…This would be a clear violation of lepton universality [13]. Most other measurements of f D + s have been hampered by a lack of statistical precision, and relatively large systematic errors [14,15,16,17,18,19]. One large systematic error source has been the lack of knowledge of the absolute branching fraction of the normalization channel, usually D + s → φπ + [20].…”

THE RADIATIVE LEPTONIC $B_c\to \tau \bar \nu_\tau\gamma$ DECAY IN TWO-HIGGS DOUBLET MODEL

“…For large tanβ the most stringent constraints on tanβ and M H are actually on their ratio, tanβ/M H . The current limits come from the measured branching ratio for the inclusive decay B → Xτν, giving tanβ/M H < 0.46 GeV −1 [20], and from the upper limit on the branching ratio for B → τν, giving tanβ/M H < 0.38 GeV −1 [21]. In model I the situation is somewhat totally different.…”

Rare Radiative and Leptonic B Decays: Recent Results from BaBar and Belle

“…Depending on the state of external knowledge of f B |V ub |, a measurement could either provide this product (within the SM) or provide evidence for new physics (e.g., a charged Higgs, or leptoquark exchange). The most stringent published limit is from L3 [31], < 5.7 × 10 −4 at 90% CL. BABAR now has two new independent preliminary results, both using 81.9 fb −1 of data:…”