B0→D0Dˉ0K0B^0 \to D^0 \bar D^0 K^0, B+→D0Dˉ0K+B^+ \to D^0 \bar D^0 K^+ and the scalar DDˉD \bar D bound state

We study the $B^0$ decay to $D^0 \bar D^0 K^0$ based on the chiral unitary model that generates the X(3720) resonance, and make predictions for the $D^0 \bar D^0$ invariant mass distribution. From the shape of the distribution, the existence of the resonance below threshold could be induced. We also predict the rate of production of the X(3720) resonance to the $D^0 \bar D^0$ mass distribution with no free parameters.Comment: 9 pages, 17 figure

Observation of B0→D+D−B^0 \to D^+ D^-, B−→D0D−B^- \to D^0 D^- and B−→D0D∗−B^- \to D^0 D^{*-} decays

We report the first observation of the decay modes $B^0 \to D^+ D^-$, $B^- \to D^0 D^-$ and $B^- \to D^0 D^{*-}$ based on 152 $\times$ 10$^6$ $B\bar{B}$ events collected at KEKB. The branching fractions of $B^0 \to D^+ D^-$, $B^- \to D^0 D^-$ and $B^- \to D^0 D^{*-}$ are found to be $(3.21 \pm 0.57 \pm 0.48) \times 10^{-4}$, $(5.62 \pm 0.82 \pm 0.65) \times 10^{-4}$ and $(4.59 \pm 0.72 \pm 0.56) \times 10^{-4}$, respectively. Charge asymmetries in the $B^- \to D^0 D^-$ and $B^- \to D^0 D^{*-}$ channels are consistent with zero.Comment: 9 pages, 2 figures, KEK Preprint 2004-99, Belle Prerpint 2005-3, submitted to PR

CP Violation in D0−D0‾D^0-\overline{D^0}Mixing

The existence of $D^0-\overline{D^0}$ mixing at a detectable level requires new physics, which effectively yields a $\Delta c = 2$ superweak interaction. In general this interaction may involve significant CP violation. For small values of the mixing it may be much easier to detect the CP-violating part of the mixing than the CP-conserving part.Comment: 3 pages, latex, no figure

Rate Measurement of D0→K+π−π0D^{0}\to K^{+}\pi^{-}\pi^{0} and Constraints on D0−D0‾D^{0} - \overline{D^{0}} Mixing

We present an observation and rate measurement of the decay D0 -> K+pi-pi0 produced in 9/fb of e+e- collisions near the Upsilon(4S) resonance. The signal is inconsistent with an upward fluctuation of the background by 4.9 standard deviations. We measured the rate of D0 -> K+pi-pi0 normalized to the rate of D0bar -> K+pi-pi0 to be 0.0043 +0.0011 -0.0010 (stat) +/- 0.0007 (syst). This decay can be produced by doubly-Cabibbo-suppressed decays or by the D0 evolving into a D0bar through mixing, followed by a Cabibbo-favored decay to K+pi-pi0. We also found the CP asymmetry A=(8 +25 -22)% to be consistent with zero.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Implication of the D^0 Width Difference On CP-Violation in D^0-\bar D^0 Mixing

Both BaBar and Belle have found evidence for a non-zero width difference in the $D^0$-$\bar D^0$ system. Although there is no direct experimental evidence for CP-violation in $D$ mixing (yet), we show that the measured values of the width difference $y\sim \Delta\Gamma$ already imply constraints on the CP-violating phase in $D$ mixing, which, if significantly different from zero, would be an unambiguous signal of new physics.Comment: 9 pages; typos remove

Branching fraction measurements of the color-suppressed decays B̅^0 to D^((*)0_π^(0), D^((*)0)η, D^((*)0)ω, and D^((*)0)η′ and measurement of the polarization in the decay B̅ 0→D^(*0)ω

We report updated branching fraction measurements of the color-suppressed decays B̅ ^(0) → D^(0)π^(0), D^(*0)π^(0), D^(0)η, D^(*0)η, D^(0)ω, D^(*0)ω, D^(0)η′, and D^(*0)η′. We measure the branching fractions (×10^(-4)): B(B̅^0 → D^(0)π^(0)) = 2.69±0.09±0.13, B(B̅^(0) → D^(*0)π^(0)) = 3.05±0.14±0.28, B(B̅^(0) → D^(0)η) = 2.53±0.09±0.11, B(B̅^(0) → D^(*0)η) = 2.69±0.14±0.23, B(B̅^(0) → D^(0)ω) = 2.57±0.11±0.14, B(B̅^(0) → D^(*0)ω) = 4.55±0.24±0.39, B(B̅^(0)→D^(0)η′) = 1.48±0.13±0.07, and B(B̅^(0) → D^(*0)n′) = 1.49±0.22±0.15. We also present the first measurement of the longitudinal polarization fraction of the decay channel D*0ω, fL=(66.5±4.7±1.5)%. In the above, the first uncertainty is statistical and the second is systematic. The results are based on a sample of (454±5)×10^6 BB̅ pairs collected at the Υ(4S) resonance, with the BABAR detector at the PEP-II storage rings at SLAC. The measurements are the most precise determinations of these quantities from a single experiment. They are compared to theoretical predictions obtained by factorization, Soft Collinear Effective Theory (SCET) and perturbative QCD (pQCD). We find that the presence of final state interactions is favored and the measurements are in better agreement with SCET than with pQCD

Can Nearby Resonances Enhance D^0 - anti-D^0 Mixing?

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 hybrid quark-antiquark-gluon Q - anti-Q G states. Assuming reasonable values for the resonance parameters we find relatively sizeable contributions from individual resonances to both \Delta m_D and \Delta \Gamma_D. We derive a variant of the GIM cancellation mechanism for the resonance amplitudes and show that broken SU(3) can allow for sizeable residual effects. Additional input from meson spectroscopy and lattice gauge simulations will be needed to improve the accuracy of these predictions.Comment: 9 pages, 3 figures, RevTeX, Shortened version for publication, (lighter resonances included and 0+ contributions dropped

D^0-\bar D^0 Mixing in Gauge-Higgs Unification

We discuss flavor mixing and resulting Flavor Changing Neutral Current (FCNC) in the SU(3) \otimes SU(3)_color gauge-Higgs unification. As the FCNC process we calculate the rate of D^0-\bar D^0 mixing due to the exchange of non-zero Kaluza-Klein gluons at the tree level. Flavor mixing is argued to be realized by the fact that the bulk mass term and brane localized mass term is not diagonalized simultaneously unless bulk masses are degenerate. It is shown that automatic suppression mechanism is operative for the FCNC processes of light quarks. We therefore obtain a lower bound on the compactification scale of order \cal O(TeV) by comparing our prediction on the mass difference of neutral D meson with the recent experimental data, which is much milder than what we naively expect assuming only the decoupling of non-zero Kaluza-Klein gluons.Comment: 26 pages, 12 figures. arXiv admin note: text overlap with arXiv:1005.245

Non-factorizable contribtion to Bd0ˉ→π0D0\bar{B_{d}^0} \to \pi^0 D^{0}

The decay modes of the type $B \to \pi \, D$ are dynamically different. For the case $\bar{B_{d}^0} \to \pi^- D^{+}$ there is a substantial factorized contribution which dominates. In contrast, the decay mode $\bar{B_{d}^0} \to \pi^0 D^{0}$ has a small factorized contribution, being proportional to a very small Wilson coefficient combination. In this paper we calculate the relevant Wilson coefficients at one loop level in the heavy quark limits, both for the $b$-quark and the $c$-quark. We also emphasize that for the decay mode $\bar{B_{d}^0} \to \pi^0 D^{0}$ there is a sizeable non-factorizable contribution due long distance interactions, which dominate the amplitude. We estimate the branching ratio for this decay mode within our framework, which uses the heavy quark limits, both for the $b$- and the $c$-quarks. In addition, we treat energetic light ($u,d,s$) quarks within a variant of Large Energy Effective Theory and combine this with a new extension of chiral quark models. For reasonable values of the model dependent parameters of our model can account for at least 3/4 of the amplitude needed to explain the experimental branching ratio $\simeq 2.6 \times 10^{-4}$.Comment: 23 pages, 4 figures, 39 reference