Strong Phase Difference Research Articles

Measurement of decay parameters for Xi- --> Lambda pi- decay.

Based on 1.35 x 10(6) polarized Xi(-) events, we measure the parameter phi(Xi) to be -1.61 degrees +/-2.66 degrees +/-0.37 degrees for the Xi(-)-->Lambda pi(-) decay. New results for the parameters beta(Xi) and gamma(Xi) are also presented. Assuming that the CP-violating phase difference is negligible, we deduce the strong phase difference between the P-wave and S-wave amplitudes of the Lambda pi final state to be 3.17 degrees +/-5.28 degrees +/-0.73 degrees, reducing the uncertainty in estimating the level of CP violation in Xi-hyperon decay.

Simultaneous solution toB→φKCPasymmetry andB→η′K,B→ηK*branching ratio anomalies fromR-parity violation

The branching ratios for the neutral and charged B decay channels to $\eta' K$ and $\eta K^*$ are well above the Standard Model expectations. Moreover, the mixing-induced CP asymmetry in $B \to \phi K_S$ is incompatible to that found in $B\to J/\psi K_S$. We investigate whether a flavour-specific tree-level $b\to s \bar{s} s$ operator coming from R-parity violating supersymmetry can resolve both these discrepancies, without jeopardizing those results which are in agreement with the Standard Model. We found that it is possible to have a parameter space satisfying all these requirements, including that of a low strong phase difference compatible with the color transparency argument. Furthermore, we put a robust bound on the relevant coupling, which is two orders of magnitude better than the existing one.

Measurement ofB(B−→D0π−)andB(B0→D+π−)and isospin analysis ofB¯→Dπdecays

We present new measurements of branching fractions for the color-favored decays B−→D0π− and B0→D+π−. Using 9.67×106BB¯ pairs collected with the CLEO detector, we obtain the branching fractions B(B−→D0π−)=(49.7±1.2±2.9±2.2)×10−4 and B(B0→D+π−)=(26.8±1.2±2.4±1.2)×10−4. The first error is statistical, the second is systematic, and the third is due to the experimental uncertainty on the production ratio of charged and neutral B mesons in Υ(4S) decays. These results, together with the current world average for the color-suppressed branching fraction B(B0→D0π0), are used to determine the cosine of the strong phase difference δI between the I=1/2 and I=3/2 isospin amplitudes. We find cosδI=0.863−0.023−0.035−0.030+0.024+0.036+0.038, and obtain a 90% confidence interval of 16.5°<δI<38.1°. This nonzero value of δI suggests the presence of final state interactions in the Dπ system.Received 12 June 2002DOI:https://doi.org/10.1103/PhysRevD.66.031101©2002 American Physical Society

Final state rescattering and color-suppressedB0→D(*)0h0decays

The color-suppressed \bar B^0-> D^{(*)0}\pi^0, D^{(*)0}\eta, D^0\omega decay modes have just been observed for the first time. The rates are all larger than expected, hinting at the presence of final state interactions. Considering \bar B^0-> D^{(*)0}\pi^0 mode alone, an elastic D^{(*)}\pi -> D^{(*)}\pi rescattering phase difference \delta \equiv \delta_{1/2} - \delta_{3/2} \sim 30^\circ would suffice, but the \bar B^0-> D^{(*)0}\eta, D^0\omega modes compel one to extend the elastic formalism to SU(3) symmetry. We find that a universal a_2/a_1=0.25 and two strong phase differences 20^\circ \sim \theta < \delta < \delta^\prime \sim 50^\circ can describe both DP and D^*P modes rather well; the large phase of order 50^\circ is needed to account for the strength of {\it both} the D^{(*)0}\pi^0 and D^{(*)0}\eta modes. For DV modes, the nonet symmetry reduces the number of physical phases to just one, giving better predictive power. Two solutions are found. We predict the rates of the \bar B^0-> D^{+}_s K^-, D^{*+}_s K^-, D^0\rho^0, D^+_s K^{*-} and D^0\phi modes, as well as \bar B^0-> D^{0}\bar K^0, D^{*0}\bar K^0, D^{0}\bar K^{*0} modes. The formalism may have implications for rates and CP asymmetries of charmless modes.

Systematics of large axial vector meson production in heavy flavor weak decays

Branching ratios observed for $D$ and B decays to final states $a_1(1260)^{\pm} X$ are comparable to those for corresponding decays to $\pi^{\pm} X$ and $\rho^{\pm} X$ and much larger than those for all other decays. Implications are discussed of a "vector-dominance model" in which a $W$ is produced and immediately turns into an axial vector, vector or pseudoscalar meson. Data for decays to all such final states are shown to have large branching ratios and satisfy universality relations. Upper limits on small strong phase differences between amplitudes relevant to CP violation models are obtained from analysis of the predicted and observed suppression of $B^o$ decays into neutral final states $\pi^o X^o$, $\rho^oX^o$ and $a_1^o X^o$. . Branching ratios of $\approx 1%$ are predicted for the as yet unobserved presence of the $D_{s1}(2536)$ charmed-strange axial vector in B decays.

Measuring D0– [formula omitted] mixing and relative strong phases at a charm factory

We propose a set of measurements at a charm factory to determine the D 0– D ̄ 0 mixing parameters ΔM and ΔΓ and the strong phase difference δ between doubly-Cabibbo-suppressed (DCS) and Cabibbo-favored (CF) neutral D decays into K − π +. The method can also be used to measure strong phase differences between other corresponding DCS and CF amplitudes. These phase differences are important for studies of D 0– D ̄ 0 mixing.

Phenomenological issues in the determination of ΔΓD

We consider the issue of determining the D 0– D ̄ 0 width difference ΔΓ D experimentally. The current situation is reviewed and suggestions for further study are given. We propose a number of D 0 decay modes in addition to those studied in the recent E791, FOCUS and BELLE lifetime determination experiments. Then we address prospects for determining CF-CDS strong phase differences, like δ Kπ which appears in the CLEO study of D 0→ K + π − transitions. We show how to extract δ K ∗π with CDS data and furthermore show when D→ K L π data becomes available that δ Kπ can also be obtained.

Impact of |{Delta}I|=5/2 transitions in K{yields}{pi}{pi} decays

We consider the impact of isospin violation on the analysis of K{yields}{pi}{pi} decays. We scrutinize, in particular, the phenomenological role played by the additional weak amplitude, of |{Delta}I|=5/2 in character, incurred by the presence of isospin violation. We show that Watson's theorem is appropriate in O(m{sub d}-m{sub u}), so that the inferred {pi}{pi} phase shift at s=m{sub K} determines the strong phase difference between the I=0 and I=2 amplitudes in K{yields}{pi}{pi} decay. We find the magnitude of the |{Delta}I|=5/2 amplitude thus implied by the empirical branching ratios to be larger than expected from estimates of isospin-violating strong and electromagnetic effects. We effect a new determination of the octet and 27-plet coupling constants with strong-interaction isospin violation and with electromagnetic effects, as computed by Cirigliano, Donoghue, and Golowich, and find that we are unable to resolve the difficulty. Exploring the role of |{Delta}I|=5/2 transitions in the CP-violating observable {epsilon}{prime}/{epsilon}, we determine that the presence of a |{Delta}I|=5/2 amplitude impacts the empirical determination of {omega}, the ratio of the real parts of the |{Delta}I|=3/2 to |{Delta}I|=1/2 amplitudes, and that it generates a decrease in the estimation of {epsilon}{prime}/{epsilon}.

Impact of|ΔI|=5/2transitions inK→ππdecays

We consider the impact of isospin violation on the analysis of K-> pi pi decays. We scrutinize, in particular, the phenomenological role played by the additional weak amplitude, of |Delta I|=5/2 in character, incurred by the presence of isospin violation. We show that Watson's theorem is appropriate in O(m_d-m_u), so that the inferred pi-pi phase shift at sqrt{s}=m_K determines the strong phase difference between the I=0 and I=2 amplitudes in K-> pi pi decay. We find the magnitude of the |Delta I|=5/2 amplitude thus implied by the empirical branching ratios to be larger than expected from estimates of isospin-violating strong and electromagnetic effects. We effect a new determination of the octet and 27-plet coupling constants with strong-interaction isospin violation and with electromagnetic effects, as computed by Cirigliano, Donoghue, and Golowich, and find that we are unable to resolve the difficulty. Exploring the role of |Delta I|=5/2 transitions in the CP-violating observable epsilon'/epsilon, we determine that the presence of a |Delta I|=5/2 amplitude impacts the empirical determination of omega, the ratio of the real parts of the |Delta I|=3/2 to |Delta I|=1/2 amplitudes, and that it generates a decrease in the estimation of epsilon'/epsilon.

Weak phases from B decays to kaons and charged pions.

Phases of elements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix can be obtained using decays of $B$ mesons to $\pi^+ \pi^-$, $\pi^\pm K^\mp$, and $\pi^+ K^0$ or $\pi^- \overline{K}^0$. For $B^0~{\rm or}~ \overline{B}^0 \to \pi^+ \pi^-$, one identifies the flavor of the neutral $B$ meson at time of production and studies the time-dependence of the decay rate. The other processes are self-tagging and only their rates need be measured. By assuming flavor SU(3) symmetry and first-order SU(3) breaking, one can separately determine the phases $\gamma \equiv {\rm Arg}~V_{ub}^*$ and $\alpha = \pi - \beta - \gamma$, where $\beta \equiv {\rm Arg}~V_{td}^*$. Special cases include the vanishing of strong interaction phase differences between amplitudes, the possibility of recovering partial information when $\pi^+ \pi^-$ and $\pi^\pm K^\mp$ decays cannot be distinguished from one another, and the use of a correlation between $\gamma$ and $\alpha$ in the region of allowed parameters.