Soft Nonfactorizable Contribution to \bar{B}^0 \to D^0\pi^0

For the color-suppressed $\bar{B}^0\longrightarrow D^{0}\pi^{0}$ decay, nonfactorizable contributions are expected to be leading and naive factorization description breaks down. We estimate $1/m_b$ power-suppressed nonfactorizable effect in $\bar{B}^0\longrightarrow D^{0}\pi^{0}$, which is due to soft exchange between the emitted heavy-light quark pair and $B\pi$ system, in the framework of QCD light-cone sum rules (LCSR). The resulting correction to the decay amplitude is found to be numerically comparable with the corresponding factorizable piece, estimated at about $(50-110)$ of the latter. The relevant parameter $a_2$ receives a positive number contribution, due to the factorizable correction and the power-suppressed soft effect. Our findings would be crucial to phenomenological understanding of the $\bar{B}^0\longrightarrow D^{0}\pi^{0}$ decay.Comment: 15 pages, revtex, accepted for publication in EPJ

Revisiting Charmless Two-Body B Decays involving η′\eta^{\prime} and η\eta

We have studied charmless two-body B decays involving $\eta$ and $\eta'$ in the framework of QCD improved factorization appraoch. The spectator hard scattering mechanism for $\eta'$ production have been re-examined and extended, which contributions are incorporated consistently into the factorizable leading contributions. It is found that the conventional mechanism would give $Br(B\to \eta' K)\sim 30\times 10^{-6}$ which agrees with predictions based on naive factorization approaches. With the incorporation of spectator hard scattering mechanism contributions, theoretical predictions are improved much and the bulk of $Br(B\to \eta' K)$ are accommodated in the reasonable parameter space. We have also presented calculations of $g^{\ast}g^{\ast}-\eta^{(\prime)}$ transition form factors within the standard hard scattering approach. It is shown that the new contributions in the modes such as $B\to \eta' +vector$ and $B\to \eta+ \pi, \rho, K^{(\ast)}$ are small. Direct CP-violation in those decay modes are predicted. It is shown that the prospects for measuring direct CP-violation effects in $B^{\pm} \to$ $\eta' K^{\pm}$, $\eta' \pi^{\pm}$, $\eta \pi^{\pm}$, and $\eta K^{\pm}$ are promising at B factories in the near future.Comment: 34 pages, 5 figures. Title changed, text polished and some statements softene

Systematic Study on QCD Interactions of Heavy Mesons with ρ\rho Meson

The strong interactions of the negative-parity heavy mesons with $\rho$ meson may be described consistently in the context of an effective lagrangian, which is invariant under isospin SU(2) transformation. Four coupling constants $g_{HH\rho}$, $f_{H^*H\rho}$, $g_{H^*H^*\rho}$ and $f_{H^*H^*\rho}$ enter the effective lagrangian, where $H$ $(H^*)$ denotes a pseudoscalar bottom or charm meson (the corresponding vector meson). Using QCD light cone sum rule (LCSR) method and, as inputs, the hadronic parameters updated recently, we give an estimate of $g_{H^*H^*\rho}$ and $f_{H^*H^*\rho}$, about which little was known before, and present an improved result for $g_{HH\rho}$ and $f_{H^*H\rho}$. Also, we examine the heavy quark asymptotic behavior of these nonperturbative quantities and assess the two low energy parameters $\beta$ and $\lambda$ of the corresponding effective chiral lagrangian.Comment: 16 pages, 1 eps figure, version to appear in PL

Image Anaysis and Deep Learning for Aiding Professional Coin Grading

International audienceCoin grading means evaluating coins’ physical condition. In this paper, we proposed a process for coin grading by quantification of "unexpected elements" such as scratches and dirty marks. We detect respectively significant and tiny “unexpected elements” with the help of handcrafted filters and Deep Learning techniques. The result of our process, which is close to the manual expert one, is considered as a useful help for numismatists