Power corrections in charmless B decays

Power corrections seem to play an important role in charmless B decays as indicated by recent analysis using QCD Factorization. In this talk, I would like to report on a recent work on power corrections in charmless B decays. By using the ratio of the branching fraction of $B^+ \to \pi^+ K^{\ast 0}$ to that of $B^0 \to \pi^- \rho^+$, for which the theoretical uncertainties are greatly reduced, it is shown in a transparent manner that power corrections in charmless B decays are probably large and that the $B^0 \to K^- \rho^+$ decay could be explained with the annihilation term included. For ratios of direct CP asymmetries, QCD Factorisation with the annihilation terms included would predict the direct CP asymmetry of $B \to \pi^+ \pi^-$ to be about 3 times larger than that of $B \to \pi^\pm K^\mp$, with opposite sign. In particular, the large measured value for $B \to \pi^\pm K^\mp$ CP asymmetry implies naturally a corresponding large $B \to \pi^+ \pi^-$ CP asymmetry as observed by Belle. Experimentally any significant deviation from this prediction or possibly the importance of long-distance rescattering effects.Comment: Talk given at the QCD Euroconference 2004, Montpellier 5-9 July 2004., LateX, 7 pages, 2 figure

Relations for Direct CP asymmetries \\in B→PPB\to \rm PP and B→PVB\to \rm PV decays

The presence of additional strong phase from power corrections and other chirally enhanced terms makes it more difficult to predict direct CP asymmetries in two-body charmless B decays. In this talk, I would like to report on a recent work on QCD Factorisation and Power Corrections in Charmless B Decays. Using the measured branching ratios for $B\to \rm PV$, it is shown that power corrections in charmless B decays are probably large, at least for penguin dominated $\rm PV$ channels. Since the tree-penguin interference responsible for direct CP asymmetries in two-body charmless B decays are related by CKM factors and SU(3) symmetry, we find that, if power corrections other than the chirally enhanced power corrections and annihilation topology were negligible, QCD Factorisation would predict the direct CP asymmetry of $B \to \pi^+ \pi^-$ to be about 3 times larger than that of $B \to \pi^\pm K^\mp$, with opposite sign, in agreement with the latest measurement from Belle. Similar relations are also given for direct CP asymmetries in $B\to\rm PV$ .Comment: Talk given at the QCD@Work 2005, Conversano, Bari, Italy, 16-20 June 2005, LateX, 7 pages, 2 figures, to appear in the Proceeding

Test of SU(3) Symmetry in Hyperon Semileptonic Decays

Existing analyzes of baryon semileptonic decays indicate the presence of a small SU(3) symmetry breaking in hyperon semileptonic decays, but to provide evidence for SU(3) symmetry breaking, one would need a relation similar to the Gell-Mann Okubo(GMO) baryon mass formula which is satisfied to a few percents, showing evidence for SU(3) symmetry breaking in the divergence of the vector current matrix element. In this paper, we shall present a similar GMO relation for the hyperon semileptonic decay axial vector form factors. Using these relations and the measured axial vector current to vector current form factor ratios, we show that SU(3) symmetry breaking in hyperon semileptonic decays is of 5-11%.Comment: v3, LaTex, 8 pages, published versio

η−η′\eta-\eta^{\prime} mixing

The $\eta -\eta^{\prime}$ mixing mass term due to the derivative coupling $SU(3)\times SU(3)$ symmetry breaking term, produces an additional momentum-dependent pole term for processes with $\eta^{\prime}$, but is suppressed in the $\eta$ amplitude by a factor $m_{\eta}^{2}/m_{\eta^{\prime}}^{2}$. This seems to be the origin of the two-angle description of the pseudo-scalar decay constants used in the literature. In this paper, by diagonalizing both the mixing mass term and the momentum-dependent mixing term, we show that the $\eta -\eta^{\prime}$ system could be described by a meson field renormalization and a new mixing angle $\theta$ which differs from the usual mixing angle $\theta_{P}$ by a small momentum-dependent mixing $d$ term. This new mixing scheme with exact treatment of the momentum-dependent mixing term, is actually simpler than the perturbation treatment and should be used in any determination of the $\eta -\eta^{\prime}$ mixing angle and the momentum-dependent mixing term. Assuming nonet symmetry for the $\eta_{0}$ singlet amplitude, from the sum rules relating $\theta$ and $d$ to the measured vector meson radiative decays amplitudes, we obtain consistent solutions with $\theta=-(13.99\pm 3.1)^{\circ}$, $d=0.12\pm 0.03$ from $\rho\to\eta\gamma$ and $\eta^{\prime}\to\rho\gamma$ decays, for $\omega$ , $\theta=-(15.47\pm 3.1)^{\circ}$, $d=0.11\pm 0.03$, and for $\phi$, $\theta=-(12.66\pm 2.1)^{\circ}$, $d=0.10\pm 0.03$. It seems that vector meson radiative decays would favor a small $\eta-\eta^{\prime}$ mixing angle and a small momentum-dependent mixing term.Comment: LaTeX, 11 pages, v2, text and references added, to appear in PR

CP-violating asymmetry in B−→π+π−K−B^- \to \pi^+ \pi^- K^- and B−→K+K−K−B^- \rarr K^+ K^- K^- decays

The recent Belle and Babar measurements of the branching ratios $B^- \to \pi^+ \pi^- K^-$ and $B^- \to K^+ K^- K^-$ and $B^\pm \to \chi_{c0} K^\pm$ have renewed interests in these decays as another mean to look for direct CP violation in B decays. In this talk, I would like to discuss a recent analysis of the CP violating asymmetry in the partial widths for the decays $B^- \to \pi^+ \pi^- K^-$ and $B^- \to K^+ K^- K^-$, which results from the interference of the non resonant amplitude with the resonant amplitude $B^\pm \to \chi_{c0} K^\pm$ $\rarr\pi^+ \pi^- K^\pm$ and $B^\pm \to \chi_{c0} K^\pm$ $\to K^+ K^- K^\pm$. For $\gamma \simeq 58^o$ we predict that the partial width asymmetry could reach 10% for the $B^- \to \pi^+ \pi^- K^-$ decay and 16% for the $B^- \to K^+ K^- K^-$decay.Comment: Talk given at the Quark Confinement and Hadron Spectrum V, Gargnano,Italy,10-14 September 2002, LaTeX,4 page

Charming penguin in nonleptonic B decays

In the study of two-body charmless B decays as a mean of looking for direct CP-violation and measuring the CKM mixing parameters in the Standard Model, the short-distance penguin contribution with its absorptive part generated by charm quark loop seems capable of producing sufficient $B \to K\pi$ decays rates, as obtained in factorization and QCD-improved factorization models. However there are also long-distance charming penguin contributions which also give rise to a strong phase due to the rescattering $D^{*}D^{*} \to K\pi$ . In this talk, I would like to discuss \cite{Isola} a recent work on the long-distance charming penguin as a a different approach to the calculation of the penguin contributions in $B \to K\pi$ decays from charmed meson intermediate states. Using chiral effective Lagrangian for light and heavy mesons, corrected for hard pion and kaon momenta, we show that the charming-penguin contributions increase significantly the $B \to K\pi$ decays rates from its short-distance contributions, giving results in better agreement with experimental data.Comment: Talk given at the International Workshop on QCD: Theory and Experiment, Martina Franca, Italy, 16--20 June 2001, LaTex, 9 page