Cheng, Shan; Khodjamirian, Alexander; Virto Iñigo, Javier (2017). B →ππ form factors from lightcone sum rules with Bmeson distribution amplitudes. Journal of High Energy Physics, 2017(5), pp. 125. Springer 10.1007/JHEP05(2017)157

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We study B → ππ form factors using QCD lightcone sum rules with Bmeson distribution amplitudes. These form factors describe the semileptonic decay B → ππlν ̄l, and constitute an essential input in B → ππl+l− and B → πππ decays. We employ the correlation functions where a dipion isospinone state is interpolated by the vector lightquark current. We obtain sum rules where convolutions of the Pwave B ̄0 → π+π0 form factors with the timelike pion vector form factor are related to universal Bmeson distribution amplitudes. These sum rules are valid in the kinematic regime where the dipion state has a large energy and a low invariant mass, and reproduce analytically the known lightcone sum rules for B → ρ form factors in the limit of ρdominance and zero width, thus providing a systematics for so far unaccounted corrections to B → ρ transitions. Using data for the pion vector form factor, we estimate finitewidth effects and the contribution of excited ρresonances to the B → ππ form factors. We find that these contributions amount up to ∼ 20% in the small dipion mass region where they can be effectively regarded as a nonresonant (P wave) background to the B → ρ transition.
Item Type: 
Journal Article (Original Article) 

Division/Institute: 
10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC) 08 Faculty of Science > Institute of Theoretical Physics 
UniBE Contributor: 
Virto Iñigo, Javier 
Subjects: 
500 Science > 530 Physics 
ISSN: 
10298479 
Publisher: 
Springer 
Language: 
English 
Submitter: 
Esther Fiechter 
Date Deposited: 
27 Oct 2017 15:29 
Last Modified: 
27 Oct 2017 15:29 
Publisher DOI: 
10.1007/JHEP05(2017)157 
ArXiv ID: 
1701.01633 
BORIS DOI: 
10.7892/boris.102348 
URI: 
https://boris.unibe.ch/id/eprint/102348 