1,183 research outputs found
Model Independent Extractions of |V_{ub}| from Inclusive B Decays
We discuss the possibility of extracting |V_{ub}| from various spectra of
inclusive B decays, without large systematic errors which usually arise from
having to model the Fermi motion of the heavy quark. This strategy can be
applied to the electron energy spectrum, as well as the hadronic mass spectrum.
Modulo violation of local hadron-parton duality, the theoretical error in the
extraction is estimated to be less than 10%.Comment: 3 pages. talk given at DPF 2000, Columbus, OH, August 11, 200
Ward Identity and Scattering Amplitudes for Nonlinear Sigma Models
We present a Ward identity for nonlinear sigma models using generalized
nonlinear shift symmetries, without introducing current algebra or coset space.
The Ward identity constrains correlation functions of the sigma model such that
the Adler's zero is guaranteed for -matrix elements, and gives rise to a
subleading single soft theorem that is valid at the quantum level and to all
orders in the Goldstone decay constant. For tree amplitudes, the Ward identity
leads to a novel Berends-Giele recursion relation as well as an explicit form
of the subleading single soft factor. Furthermore, interactions of the cubic
biadjoint scalar theory associated with the single soft limit, which was
previously discovered using the Cachazo-He-Yuan representation of tree
amplitudes, can be seen to emerge from matrix elements of conserved currents
corresponding to the generalized shift symmetry.Comment: 5 page
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