Limit on a Right-Handed Admixture to the Weak $b \to c$ Current from Semileptonic Decays
| Autor: | Feger, Robert, Klose, Verena, Lacker, Heiko, Lueck, Thomas, Mannel, Thomas |
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| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | Phys.Rev.D82:073002,2010 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevD.82.073002 |
| Popis: | We determine an upper bound for a possible right-handed $b{\to}c$ quark current admixture in semileptonic $\bar{B} \to X_{c} \ell^{-} \bar{\nu}$ decays from a simulateous fit to moments of the lepton-enery and hadronic-mass distribution measured as a function of the lower limit on the lepton energy, using data measured by the \babar\ detector. The right-handed admixture is parametrized by a new parameter $c_R$ as coefficient of computed moments with right-handed quark current. For the standard model part we use the prediction of the heavy-quark expansion (HQE) up to order $1/m_b^3$ and perturbative corrections and for the right-handed contribution only up to order $1/m_b^2$ and perturbative corrections. We find $\cR=0.05\asympm{+0.33}{-0.50}$ in agreement with the standard-model prediction of zero. Additionally, we give a contraint on a possible right-handed admixture from exclusive decays, which is with a value of $\cR =0.01{\pm}0.03$ more restrictive than our value from the inclusive fit. The difference in \Vcb between the inclusive and exclusive extraction is only slightly reduced when allowing for a right-handed admixture in the range of $\cR=0.01 {\pm} 0.03$. Comment: 7 pages, 3 figures, 2 tables |
| Databáze: | arXiv |
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