Abstract
Amplitude models are constructed to describe the resonance structure of {D^{0}rightarrow K^{-}pi ^{+}pi ^{+}pi ^{-}} and {D^{0} rightarrow K^{+}pi ^{-}pi ^{-}pi ^{+}} decays using pp collision data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb^{-1}. The largest contributions to both decay amplitudes are found to come from axial resonances, with decay modes D^{0} rightarrow a_1(1260)^{+} K^{-} and D^{0} rightarrow K_1(1270/1400)^{+} pi ^{-} being prominent in {D^{0}rightarrow K^{-}pi ^{+}pi ^{+}pi ^{-}} and D^{0}rightarrow K^{+}pi ^{-}pi ^{-}pi ^{+}, respectively. Precise measurements of the lineshape parameters and couplings of the a_1(1260)^{+}, K_1(1270)^{-} and K(1460)^{-} resonances are made, and a quasi model-independent study of the K(1460)^{-} resonance is performed. The coherence factor of the decays is calculated from the amplitude models to be R_{K3pi } = 0.459pm 0.010,(mathrm {stat}) pm 0.012,(mathrm {syst}) pm 0.020,(mathrm {model}), which is consistent with direct measurements. These models will be useful in future measurements of the unitary-triangle angle gamma and studies of charm mixing and C!P violation.
Highlights
The decays1 D0 → K −π +π +π − and D0 → K +π −π +π − have an important role to play in improving knowledge of the Cabibbo–Kobayashi–Maskawa (CKM) unitarity-triangle angle γ ≡ arg(−Vud Vu∗b/Vcd Vc∗b)
Studies of charm mixing and searches for CP violation in the D0–D0 system, which for these final states have only been performed inclusively [4], will benefit from an understanding of the variation of the decay amplitudes across their phase space. These decay modes are a rich laboratory for examining the behaviour of the strong interaction at low energy, through studies of the intermediate resonances that contribute to the final states
The decay D0 → K +π −π −π + is dominated by doubly Cabibbosuppressed (DCS) amplitudes, with small contributions from mixing-related effects, and occurs at a rate that is suppressed by a factor of (3.22±0.05)×10−3 [4] compared to that of the favoured mode
Summary
The decays D0 → K −π +π +π − and D0 → K +π −π +π − have an important role to play in improving knowledge of the Cabibbo–Kobayashi–Maskawa (CKM) unitarity-triangle angle γ ≡ arg(−Vud Vu∗b/Vcd Vc∗b) Sensitivity to this parameter can be obtained by measuring CP-violating and associated observables in the decay B− → D K −, where D indicates a neutral charm meson reconstructed in final states common to both D0 and D0, of which K ∓π ±π ±π ∓ are significant examples [1,2]. Studies of charm mixing and searches for CP violation in the D0–D0 system, which for these final states have only been performed inclusively [4], will benefit from an understanding of the variation of the decay amplitudes across their phase space These decay modes are a rich laboratory for examining the behaviour of the strong interaction at low energy, through studies of the intermediate resonances that contribute to the final states.
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