相关论文: Dipenguin-like contributions to D0 - anti-D0 mixin…
We study the impact of the four-quark dipenguin operator to the D^0 - \bar D^0 mixing. It is shown to contribute to the short distance piece at the same order of magnitude as the box diagram.
The D^0-D^0(bar) mixing is analyzed in a weak gauged U(4)_L x U(4)_R chiral lagrangian model where the electroweak interaction is introduced as a gauge theory over the meson degrees of freedom. This model allows a particular realization of…
Theoretical predictions for the $D^0\overline{D^0}$ mixing parameters fall significantly short of experimental measurements, with discrepancies spanning several orders of magnitude. This gap is mainly due to the Glashow-Iliopoulos-Maiani…
We consider the possibility that D^0 - anti-D^0 mixing undergoes resonant enhancement. Various scenarios are explored, including the potential effects of nearby pseudoscalar or scalar quark-antiquark (Q - anti-Q) resonances as well as of…
The nonperturbative content of the QCD vacuum permits the occurrence of QCD-vaccum condensate contributions to penguin amplitudes. We calculate the dimension-4 $<m_q\bar qq>$ and $<\alpha_s G^2>$ contributions to the effective Wilson…
We compute for the first time the long-distance penguin contribution to the double radiative $B$-meson decays due to the purely hadronic operators acting with the electromagnetic current in the background soft-gluon field from first…
In view of difficulty to reproduce observables in the $D^0-\bar{D}^0$ mixing via the operator product expansion, we discuss the Dyson-Schwinger approach to this process. Formulated by the parametrization of quark propagators, SU(3) breaking…
We provide a comprehensive, up-to-date analysis of possible New Physics contributions to the mass difference $\Delta M_D$ in $D^0$-${\bar D}^0$ mixing. We consider the most general low energy effective Hamiltonian and include leading order…
We consider the long distance contributions to inclusive penguin processes through processes like $b\rightarrow s V$ and $b\rightarrow d V$ where $V$ are $^3S_1(c\bar c)$ states $\psi_i$ in the former case and include $\rho$, $\omega$ for…
Observables in the $D^0-\bar{D}^0$ mixing can be theoretically analyzed by the operator product expansion (OPE), in which $1/m_c$ is regarded as an expansion parameter. Since the contributions of four-quark operators are strongly suppressed…
It is usually argued that the Standard Model predicts slow D^0-\bar D^0 oscillations with \Delta M_D, \Delta \Gamma_D < 10^{-3}*\Gamma_D$ and that New Physics can reveal itself through \Delta M_D exceeding 10^{-3}*\Gamma_D. It is believed…
The precision of the CP phases $2\beta$ and $2\beta_s$ determined from the mixing-induced CP asymmetries in $B_d\to J/\psi K_S$ and $B_s\to J/\psi \phi$, respectively, is limited by the unknown long-distance contribution of a penguin…
The standard model contribution to $\epsilon'/\epsilon$ of the magnetic- and electric-dipole penguin operators $Q_{11} = \frac{g_s}{16\pi^2} \, m_s \: \bar{s}\, \sigma_{\mu\nu} t^a G^{\mu\nu}_a (1-\gamma_5 )\, d $ and $Q_{12} =…
We re-visit the problem of non-perturbative contribution to the mass difference in D0-D0bar mixing within the Standard Model (SM). There are two known approaches to take this contribution into account. In the long long-distance approach one…
We investigate the contributions coming from the penguin operators in the nonresonant $B^- \to M \bar M \pi^-$ ($M =\pi^-, K^-, K^0$) decays. The effective Wilson coefficients of the the strong penguin operators $O_{4,6}$ are found to be…
We point out that the standard chromomagnetic penguin dipole operator has a counterpart corresponding to off-shell momenta for external quarks. By employing the chiral quark model, we show that this new dipole penguin operator has the same…
A significant discrepancy, spanning multiple orders of magnitude, exists between the leading order contribution to the $D^0\overline{D^0}$ mixing parameters and experimental values. This is largely due to the Glashow-Iliopoulos-Maiani (GIM)…
Long-distance contributions of operators of the effective non-leptonic weak Hamiltonian containing charmed currents have been recently studied. Penguin-like contractions of these operators, denoted as charming penguins, have been shown to…
In the analysis of \epsilon^\prime/\epsilon it has been traditional to consider the isospin-breaking effects arising from electroweak-penguin contributions and from \pi^0-\eta and \pi^0-\eta^\prime mixing, yet additional isospin-violating…
Contributions of low energy "eye" and "figure-eight" quark diagrams to the $K \rightarrow \pi$ weak transitions are studied in a hadron- level phenomenological approach. It is shown that these contributions may be estimated by considering…