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Register a new userSimultaneous investigation of the $mathbf{T=1~ (J^{pi}=0^+)}$ and $mathbf{T=0 ~ (J^{pi}=9^+)}$ $beta$ decays in $^{70}$Br
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The $beta$ decay of the odd-odd nucleus $^{70}$Br has been investigated with the BigRIPS and EURICA setups at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center. The $T=0$ ($J^{pi}=9^+$) and $T=1$ ($J^{pi}=0^+$) isomers have both been produced in in-flight fragmentation of $^{78}$Kr with ratios of 41.6(8)% and 58.4(8)%, respectively. A half-life of $t_{1/2}=2157^{+53}_{-49}$ ms has been measured for the $J^{pi}=9^+$ isomer from $gamma$-ray time decay analysis. Based on this result, we provide a new value of the half-life for the $J^{pi}=0^+$ ground state of $^{70}$Br, $t_{1/2}=78.42pm0.51$ ms, which is slightly more precise, and in excellent agreement, with the best measurement reported hitherto in the literature. For this decay, we provide the first estimate of the total branching fraction decaying through the $2^+_1$ state in the daughter nucleus $^{70}$Se, $R(2^+_1)=1.3pm1.1%$. We also report four new low-intensity $gamma$-ray transitions at 661, 1103, 1561, and 1749 keV following the $beta$ decay of the $J^{pi}=9^+$ isomer. Based on their coincidence relationships, we tentatively propose two new excited states at 3945 and 4752 keV in $^{70}$Se with most probable spins and parities of $J^{pi}=(6^+)$ and $(8^+)$, respectively. The observed structure is interpreted with the help of shell-model calculations, which predict a complex interplay between oblate and prolate configurations at low excitation energies.
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An amplitude analysis of the $pi^{0}pi^{0}$ system produced in radiative $J/psi$ decays is presented. In particular, a piecewise function that describes the dynamics of the $pi^{0}pi^{0}$ system is determined as a function of $M_{pi^{0}pi^{0}}$ from an analysis of the $(1.311pm0.011)times10^{9}$ $J/psi$ decays collected by the BESIII detector. The goal of this analysis is to provide a description of the scalar and tensor components of the $pi^0pi^0$ system while making minimal assumptions about the properties or number of poles in the amplitude. Such a model-independent description allows one to integrate these results with other related results from complementary reactions in the development of phenomenological models, which can then be used to directly fit experimental data to obtain parameters of interest. The branching fraction of $J/psi to gamma pi^{0}pi^{0}$ is determined to be $(1.15pm0.05)times10^{-3}$, where the uncertainty is systematic only and the statistical uncertainty is negligible.
We revisit the coupled channel $Kbar{K}$ interactions and dynamically generate the resonances $f_0(980)$ and $a_0(980)$ within both the isospin and the physical bases. The $f_0(980)-a_0(980)$ mixing effects are generated in the scattering amplitudes of the coupled channels with the physical basis, which exploits the important role of the $Kbar{K}$ channel in the dynamical nature of these resonances. With the scattering amplitudes obtained, we investigate the $f_0(980)$ and $a_0(980)$ contributions to the $J/psito gammaetapi^0$, $J/psito gammapi^+pi^-$ and $J/psito gammapi^0pi^0$ radiative decays through the final-state interactions. We obtain the corresponding branching fractions $Br(J/psito gamma a_0(980) to gammaetapi^0) = (0.47pm0.05) times 10^{-7}$, $Br(J/psito gamma f_0(980) to gammapi^+pi^-) = 0.37 times 10^{-7} - 1.98 times 10^{-6}$, $Br(J/psito gamma f_0(980) to gammapi^0pi^0) = 0.18 times 10^{-7} - 9.92 times 10^{-7}$, and predict $Br(J/psito gamma a_0(980)) = 1.72 times 10^{-8} - 3.07times 10^{-7}$ and $Br(J/psito gamma f_0(980)) = 1.86 times 10^{-8} - 1.89times 10^{-5}$. These fractions are within the upper limits of the experimental measurements.
We report the first measurement of the $T$-odd moments in the decay $D^{0} rightarrow K_{S}^{0} pi^{+} pi^{-} pi^{0}$ from a data sample corresponding to an integrated luminosity of $966,{rm fb}^{-1}$ collected by the Belle experiment at the KEKB asymmetric-energy $e^+ e^-$ collider. From these moments we determine the $CP$-violation-sensitive asymmetry $a_{CP}^{Ttext{-odd}} = left[-0.28 pm 1.38 ~(rm{stat.}) ^{+0.23}_{-0.76} ~(rm{syst.})right] times 10^{-3}$, which is consistent with no $CP$ violation. In addition, we perform $a_{CP}^{Ttext{-odd}}$ measurements in different regions of the $D^{0} rightarrow K_{S}^{0} pi^{+} pi^{-} pi^{0}$ phase space; these are also consistent with no $CP$ violation.
A partial wave analysis (PWA) of the $pi^- pi^- pi^+$ and $pi^- pi^0 pi^0$ systems produced in the reaction $pi^- p to (3pi)^-p$ at 18 GeV/$c$ was carried out using an emph{isobar} model assumption. This analysis is based on 3.0M $pi^- pi^0 pi^0$ events and 2.6M $pi^- pi^-pi^+$ events and shows production of the $a_1(1260)$, $a_2(1320)$, $pi_2(1670)$ and $a_4(2040)$ resonances. Results of detailed studies of the stability of partial wave fits are presented. An earlier analysis of 250K $pi^- pi^- pi^+$ events from the same experiment showed possible evidence for a $J^{PC}=1^{-+}$ exotic meson with a mass of $sim$1.6 GeV/$c^2$ decaying into $rho pi$. In this analysis of a higher statistics sample of the $(3pi)^-$ system in two charged modes we find no evidence of an exotic meson.
Using a data sample of $e^+e^-$ collision data corresponding to an integrated luminosity of 2.93 $fb^{-1}$ collected with the BESIII detector at a center-of-mass energy of $sqrt{s}= 3.773~GeV$,we search for the singly Cabibbo-suppressed decays $D^{0}topi^{0}pi^{0}pi^{0}$, $pi^{0}pi^{0}eta$, $pi^{0}etaeta$ and $etaetaeta$ using the double tag method. The absolute branching fractions are measured to be $mathcal{B}(D^{0}topi^{0}pi^{0}pi^{0}) = (2.0 pm 0.4 pm 0.3)times 10^{-4}$, $mathcal{B}(D^{0}topi^{0}pi^{0}eta) = (3.8 pm 1.1 pm 0.7)times 10^{-4}$ and $mathcal{B}(D^{0}topi^{0}etaeta) = (7.3 pm 1.6 pm 1.5)times 10^{-4}$ with the statistical significances of $4.8sigma$, $3.8sigma$ and $5.5sigma$, respectively, where the first uncertainties are statistical and the second ones systematic. No significant signal of $D^{0}toetaetaeta$ is found, and the upper limit on its decay branching fraction is set to be $mathcal{B}(D^{0}toetaetaeta) < 1.3 times 10^{-4}$ at the $90%$ confidence level.
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