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Register a new userAmplitude analysis of the $B^+ rightarrow pi^+pi^+pi^-$ decay
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The results of an amplitude analysis of the charmless three-body decay $B^+ rightarrow pi^+pi^+pi^-$, in which $C!P$-violation effects are taken into account, are reported. The analysis is based on a data sample corresponding to an integrated luminosity of $3 text{fb}^{-1}$ of $pp$ collisions recorded with the LHCb detector. The most challenging aspect of the analysis is the description of the behaviour of the $pi^+ pi^-$ S-wave contribution, which is achieved by using three complementary approaches based on the isobar model, the K-matrix formalism, and a quasi-model-independent procedure. Additional resonant contributions for all three methods are described using a common isobar model, and include the $rho(770)^0$, $omega(782)$ and $rho(1450)^0$ resonances in the $pi^+pi^-$ P-wave, the $f_2(1270)$ resonance in the $pi^+pi^-$ D-wave, and the $rho_3(1690)^0$ resonance in the $pi^+pi^-$ F-wave. Significant $C!P$-violation effects are observed in both S- and D-waves, as well as in the interference between the S- and P-waves. The results from all three approaches agree and provide new insight into the dynamics and the origin of $C!P$-violation effects in $B^+ rightarrow pi^+pi^+pi^-$ decays.
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Utilizing the data set corresponding to an integrated luminosity of $3.19$ fb$^{-1}$ collected by the BESIII detector at a center-of-mass energy of 4.178 GeV, we perform an amplitude analysis of the $D_s^+topi^+pi^-pi^+$ decay. The sample contains 13
,797 candidate events with a signal purity of $sim$80%. We use a quasi-model-independent approach to measure the magnitude and phase of the $D_s^+topi^+pi^-pi^+$ decay, where the ${cal P}$ and ${cal D}$ waves are parameterized by a sum of three Breit-Wigner amplitudes $rho(770)^0$, $rho(1450)^0$, and $f_2(1270)$. The fit fractions of different decay channels are also reported.
We present an amplitude analysis of the decay $D^{0} rightarrow K^{-} pi^{+} pi^{+} pi^{-}$ based on a data sample of 2.93 ${mbox{,fb}^{-1}}$ acquired by the BESIII detector at the $psi(3770)$ resonance. With a nearly background free sample of about 16000 events, we investigate the substructure of the decay and determine the relative fractions and the phases among the different intermediate processes. Our amplitude model includes the two-body decays $D^{0} rightarrow bar{K}^{*0}rho^{0}$, $D^{0} rightarrow K^{-}a_{1}^{+}(1260)$ and $D^{0} rightarrow K_{1}^{-}(1270)pi^{+}$, the three-body decays $D^{0} rightarrow bar{K}^{*0}pi^{+}pi^{-}$ and $D^{0} rightarrow K^{-}pi^{+}rho^{0}$, as well as the four-body decay $D^{0} rightarrow K^{-}pi^{+}pi^{+}pi^{-}$. The dominant intermediate process is $D^{0} rightarrow K^{-}a_{1}^{+}(1260)$, accounting for a fit fraction of $54.6%$.
The decay $D^{+} rightarrow K_{S}^{0} pi^{+} pi^{+} pi^{-}$ is studied with an amplitude analysis using a data set of 2.93${mbox{,fb}^{-1}}$ of $e^+e^+$ collisions at the $psi(3770)$ peak accumulated by the BESIII detector. Intermediate states and non-resonant components, and their relative fractions and phases have been determined. The significant amplitudes, which contribute to the model that best fits the data, are composed of five quasi-two-body decays $ K_{S}^{0} a_{1}(1260)^{+}$, $ bar{K}_{1}(1270)^{0} pi^{+}$ $ bar{K}_{1}(1400)^{0} pi^{+}$, $ bar{K}_{1}(1650)^{0} pi^{+}$, and $ bar{K}(1460)^{0} pi^{+}$, a three-body decays $K_{S}^{0}pi^{+}rho^{0}$, as well as a non-resonant component $ K_{S}^{0}pi^{+}pi^{+}pi^{-}$. The dominant amplitude is $ K_{S}^{0} a_{1}(1260)^{+}$, with a fit fraction of $(40.3pm2.1pm2.9)%$, where the first and second uncertainties are statistical and systematic, respectively.
Using a low-background sample of $2.6times 10^5$ $J/psirightarrowomegaeta(omegarightarrowpi^{+}pi^{-}pi^{0},etarightarrowgammagamma)$ events, about 5 times larger statistics than previous experiments, we present a Dalitz plot analysis of the decay $omegarightarrowpi^{+}pi^{-}pi^{0}$. It is found that the Dalitz plot distribution differs from the pure $P$-wave phase space with a statistical significance of $18.9sigma$. The parameters from the fit to data are in reasonable agreement with those without the cross-channel effect within the dispersive framework, which indicates that the cross-channel effect in $omegarightarrowpi^+pi^-pi^0$ is not significant.
Based on a sample of $1.31 times 10^9$ $J/psi$ events collected with the BESIII detector, an amplitude analysis of the isospin-violating decays $eta^prime rightarrow pi^+pi^-pi^0$ and $eta^prime rightarrow pi^0pi^0pi^0$ is performed. A significant $P$-wave contribution from $eta^prime rightarrow rho^{pm} pi^{mp}$ is observed for the first time in $eta^prime rightarrow pi^+pi^-pi^0$. The branching fraction is determined to be ${mathcal B}(eta^prime rightarrow rho^{pm}pi^{mp})=(7.44pm0.60pm1.26pm1.84)times 10^{-4}$, where the first uncertainty is statistical, the second systematic, and the third model dependent. In addition to the nonresonant $S$-wave component, there is a significant $sigma$ meson component. The branching fractions of the combined $S$-wave components are determined to be ${mathcal B}(eta^prime rightarrow pi^+pi^-pi^0)_S=(37.63pm0.77pm2.22pm4.48)times 10^{-4}$ and ${mathcal B}(eta^prime rightarrow pi^0pi^0pi^0)=(35.22pm0.82pm2.54)times 10^{-4}$, respectively. The latter one is consistent with previous BESIII measurements.
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