Differences

This shows you the differences between two versions of the page.

Link to this comparison view

preprints:2002:ttp02-16 [2016/03/17 11:03] (current)
Line 1: Line 1:
 +====== TTP02-16 Gluonic Penguins in $B\to \pi\pi$ from QCD Light-Cone Sum Rules ====== 
 +  
 +  
 +   <​hidden TTP02-16 ​ Gluonic Penguins in $B\to \pi\pi$ from QCD Light-Cone Sum Rules > The $B\to \pi\pi$ hadronic matrix element 
 + of the chromomagnetic dipole operator $O_{8g}$ 
 + ​(gluonic penguin) is calculated using the QCD 
 + ​light-cone sum rule approach. The resulting sum rule for 
 + ​$\langle \pi\pi |O_{8g}|B\rangle $ contains, in addition 
 + to the $O(\alpha_s)$ part induced by hard gluon exchanges,​ 
 + a contribution due to  soft gluons. We find that in the 
 + limit $m_b\to \infty$ the soft-gluon contribution 
 + is suppressed as a second power of $1/m_b$ with respect 
 + to the leading-order factorizable $B\to \pi\pi$ amplitude,​ 
 + ​whereas the hard-gluon contribution has only an $\alpha_s$ 
 + ​suppression. Nevertheless,​ at  finite $m_b$, soft 
 + and hard effects of the gluonic penguin in $B\to \pi\pi$ 
 + are of the same order. Our result indicates that soft 
 + ​contributions are indispensable for an accurate counting 
 + of nonfactorizable effects in charmless $B$ decays. 
 + On the phenomenological side we predict that the 
 + ​impact of gluonic penguins on $\bar{B}^0_d\to \pi^+\pi^-$ 
 + is very small, but is noticeable for $\bar{B}^0_d\to \pi^0\pi^0$. 
 + </​hidden>​ 
 +|**Alexander Khodjamirian,​ Thomas Mannel and Piotr Urban** ​ |  
 +|**  Phys.Rev. ​ D67 054027 2003  **  | 
 +| {{preprints:​2002:​ttp02-16.pdf|PDF}} {{preprints:​2002:​ttp02-16.ps|PostScript}} [[http://​arxiv.org/​abs/​hep-ph/​0210378|arXiv]] ​  | 
 +| |