Zusammenfassung
We present an exploratory study of the Lambda(c,b) -> N*-form factors and the semileptonic decay width within the framework of light-cone sum rules. We use two different methods and two different interpolating currents for the Lambda(c,b). (1) We follow (Khodjamirian et al 2011 J. High Energy Phys. JHEP09(2011) 106) and eliminate negative parity partners of the Lambda(c,b) by taking linear ...
Zusammenfassung
We present an exploratory study of the Lambda(c,b) -> N*-form factors and the semileptonic decay width within the framework of light-cone sum rules. We use two different methods and two different interpolating currents for the Lambda(c,b). (1) We follow (Khodjamirian et al 2011 J. High Energy Phys. JHEP09(2011) 106) and eliminate negative parity partners of the Lambda(c,b) by taking linear combinations of different Lorentz-structures. (2) We extract the form factors by choosing the Lorentz-structures with the highest possible powers of p(+). As interpolating currents we choose an axial-vector like and a pseudoscalar like current. Our results show that the procedure of eliminating negative parity partners is not well suited for the case at hand and that the second approach with an axial-vector like interpolating current gives the most reliable results. Our predictions are based on the models obtained in (Anikin et al 2015 Phys. Rev. D 92 014018; Braun et al 2014 Phys. Rev. D 89 094511). The largest uncertainty comes from the uncertainty of the twist 4 parameters eta(10), eta(11) and we take the spread between the two models in (Anikin et al 2015 Phys. Rev. D 92 014018) as a measure for this. We get Gamma(Lambda(b) -> N*(1535)lv) = (0.0058(0.0009)(+0.0010)) x (V-ub/3.5 x 10(-3))(2), LCSR(1) Gamma(Lambda(b) -> N*(1535)lv) = (0.0070(-0.0011)(+0.0012)) x (V-ub/3.5 x 10(-3))(2), LCSR(2) Gamma(Lambda(c) -> N*(1535)lv) = (0.0064(-0.0011)(+0.0012)) x (V-cd/0.225)(2), LCSR(1) Gamma(Lambda(c) -> N*(1535)lv) = (0.00077(-0.00014)(+0.00016)) x (V-cd/0.225)(2), LCSR(2) as predictions for the respective decay widths, where LCSR(1) and LCSR(2) refer to the two different models of the distribution amplitudes of the N*. It is seen that even a rough measurement of these decays will greatly help to discriminate different models.
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