Measurement of the Semileptonic Decays B->D tau nu and B->D* tau nu
The authors present measurements of the semileptonic decays B{sup -} {yields} D{sup 0} {tau}{sup -} {bar {nu}}{sub {tau}}, B{sup -} {yields} D*{sup 0} {tau}{sup -}{bar {nu}}{sub {tau}}, {bar B}{sup 0} {yields} D{sup +} {tau}{sup -} {bar {nu}}{sub {tau}}, and {bar B}{sup 0} {yields} D*{sup +} {tau}{sup -}{bar {nu}}{sub {tau}}, which are sensitive to non-Standard Model amplitudes in certain scenarios. The data sample consists of 232 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider. They select events with a D or D* meson and a light lepton ({ell} = e or {mu}) recoiling against a fully reconstructed B meson. They perform a fit to the joint distribution of lepton momentum and missing mass squared to distinguish signal B {yields} D{sup (*)}{tau}{sup -} {bar {nu}}{sub {tau}} ({tau}{sup -} {yields} {ell}{sup -} {bar {nu}}{sub {ell}}{nu}{sub {tau}}) events from the backgrounds, predominantly B {yields} D{sup (*)} {ell}{sup -}{bar {nu}}{sub {ell}}. They measure the branching-fraction ratios R(D) {triple_bond} {Beta}(B {yields} D{tau}{sup -} {bar {nu}}{sub {tau}})/{Beta}(B {yields} D{ell}{sup -} {bar {nu}}{sub {ell}}) and R(D*) {triple_bond} {Beta}(B {yields} D*{tau}{sup -} {bar {nu}}{sub {tau}})/{Beta}(B {yields} D* {ell}{sup -} {bar {nu}}{sub {ell}}) and, from a combined fit to B{sup -} and {bar B}{sup 0} channels, obtain the results R(D) = (41.6 {+-} 11.7 {+-} 5.2)% and R(D*) = (29.7 {+-} 5.6 {+-} 1.8)%, where the uncertainties are statistical and systematic. Normalizing to measured B{sup -} {yields} D{sup (*)0} {ell}{sup -} {bar {nu}}{sub {ell}} branching fractions, they obtain {Beta}(B {yields} D{tau}{sup -} {bar {nu}}{sub {tau}}) = (0.86 {+-} 0.24 {+-} 0.11 {+-} 0.06)% and {Beta}(B {yields} D*{tau}{sup -} {bar {nu}}{sub {tau}}) = (1.62 {+-} 0.31 {+-} 0.10 {+-} 0.05)%, where the additional third uncertainty is from the normalization mode. They also present, for the first time, distributions of the lepton momentum, |P*{sub {ell}}|, and the squared momentum transfer, q{sup 2}.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76SF00515
- OSTI ID:
- 948490
- Report Number(s):
- SLAC-PUB-13532; arXiv:0902.2660; TRN: US0901663
- Journal Information:
- Physical Review D, Journal Name: Physical Review D
- Country of Publication:
- United States
- Language:
- English
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