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تسجيل مستخدم جديدThe $Bto pi ell u_ell$ semileptonic decay within the LCSR approach under heavy quark effective field theory
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The heavy quark effective field theory (HQEFT) provides an effective way to deal with the heavy meson decays. In the paper, we adopt two different correlators to derive the light-cone sum rules of the $B to pi$ transition form factors (TFFs) within the framework of HQEFT. We label those two LCSR results as LCSR-${cal U}$ and LCSR-${cal R}$, which are for conventional correlator and right-handed correlator, respectively. We observe that the correlation parameter $|rho_{rm RU}|$ for the branching ratio ${cal B}(B to pi l u_{l})$ is $sim 0.85$, implying the consistency of the LCSRs under different correlators. Moreover, we obtain $|V_{rm ub}|_{{rm LCSR}-{cal U}}=(3.45^{+0.28}_{-0.20}pm{0.13}_{rm{exp}})times10^{-3}$ and $|V_{rm ub}|_{{rm LCSR}-{cal R}} =(3.38^{+0.22}_{-0.16} pm{0.12}_{rm{exp}})times10^{-3}$. We then obtain $mathcal{R}_{pi}|_{{rm LCSR}-{cal U}}=0.68^{+0.10}_{-0.09}$ and $mathcal{R}_{pi}|_{{rm LCSR}-{cal R}}=0.65^{+0.13}_{-0.11}$, both of them agree with the Lattice QCD predictions. Thus the HQEFT provides a useful framework for studying the $B$ meson decays. Moreover, by using right-handed correlator, the twist-2 terms shall dominant the TFF $f^+(q^2)$, which approaches over $sim97%$ contribution in the whole $q^2$-region; and the large twist-3 uncertainty for the conventional correlator is greatly suppressed. One can thus adopt the LCSR-${cal R}$ prediction to test the properties of the various models for the pion twist-2 distribution amplitudes.
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