No Arabic abstract
We report the first observation of $a^{0}_{0}(980)$-$f_{0}(980)$ mixing in the decays of $J/psitophi f_{0}(980)tophi a^{0}_{0}(980)tophietapi^{0}$ and $chi_{c1}to a^{0}_{0}(980)pi^{0}to f_{0}(980)pi^{0}topi^{+}pi^{-}pi^{0}$, using data samples of $1.31times10^{9}$ $J/psi$ events and $4.48times10^{8}$ $psi(3686)$ events accumulated with the BESIII detector. The signals of $f_{0}(980)to a^{0}_{0}(980)$ and $a^{0}_{0}(980)to f_{0}(980)$ mixing are observed at levels of statistical significance of $7.4sigma$ and $5.5sigma$, respectively. The corresponding branching fractions and mixing intensities are measured and the constraint regions on the coupling constants, $g_{a_{0}K^{+}K^{-}}$ and $g_{f_{0}K^{+}K^{-}}$, are estimated. The results improve the understanding of the nature of $a^{0}_{0}(980)$ and $f_{0}(980)$.
The decays $J/psi rightarrow gamma pi^+pi^-pi^0$ and $J/psi rightarrow gamma pi^0pi^0pi^0$ are analyzed using a sample of 225 million $jpsi$ events collected with the BESIII detector. The decay of $eta(1405)ar f_{0}(980)pi^0$ with a large isospin violation is observed for the first time. The width of the $f_{0}(980)$ observed in the dipion mass spectra is anomalously narrower than the world average. Decay rates for three-pion decays of the $eta$ are also measured precisely.
Using a sample of 1.31 billion $J/psi$ events collected with the BESIII detector at the BEPCII collider, the decays $J/psi to phi pi^{+}pi^{-}pi^{0}$ and $J/psi to phi pi^{0}pi^{0}pi^{0}$ are investigated. The isospin violating decay $J/psi to phi pi^{0} f_{0}(980)$ with $f_{0}(980) to pipi$, is observed for the first time. The width of the $f_{0}(980)$ obtained from the dipion mass spectrum is found to be much smaller than the world average value. In the $pi^{0} f_{0}(980)$ mass spectrum, there is evidence of $f_1(1285)$ production. By studying the decay $J/psi to phieta$, the branching fractions of $eta to pi^{+}pi^{-}pi^{0}$ and $eta to pi^{0}pi^{0}pi^{0}$, as well as their ratio, are also measured.
A search for $B_s^0 to overline{D}^{0} f_{0}(980)$ decays is performed using $3.0, {rm fb}^{-1}$ of $pp$ collision data recorded by the LHCb experiment during 2011 and 2012. The $f_{0}(980)$ meson is reconstructed through its decay to the $pi^{+}pi^{-}$ final state in the mass window $900, {rm MeV}/c^{2} < m(pi^{+}pi^{-}) < 1080, {rm MeV}/c^{2}$. No significant signal is observed. The first upper limits on the branching fraction of $mathcal{B}(B_s^0 to overline{D}^{0} f_{0}(980)) < 3.1,(3.4) times 10^{-6}$ are set at $90,%$ ($95,%$) confidence level.
A measurement of the relative branching fraction of $B_{s}^{0} rightarrow J/ps i f_{0}(980), f_{0}(980) rightarrow pi^{+}pi^{-}$ to $B_{s}^{0} rightarrow J/psi phi, p hi rightarrow K^{+}K^{-}$ is presented. The decay mode $B_{s}^{0} rightarrow J/psi f_{0}(980)$ is an interesting mode since it is a CP-odd eigenstate which could be used in CP-violating studies. Using approximat ely 8 $rm{fb}^{-1}$ of data recorded with the D0 detector at the Fermilab Tevatron Collider, a relative branching fraction of 0.210 $pm$ 0.032thinspace(stat) $pm$ 0.036thi nspace(syst) is found.
We report a measurement of differential cross section of $pi^{0}$ pair production in single-tag two-photon collisions. These results are obtained with 759$fb^{-1}$ of the data collected with the Belle detector at the KEKB asymmetric energy $e^{+}e^{-}$ collider. The cross section is measured for $Q^{2}$ up to 30 GeV$^{2}$, where $Q^{2}$ is the negative of the invariant mass squared of the tagged virtual photon, in the kinematic range 0.5 GeV < $W$ < 2.1 GeV and |cos$theta^{*}$| < 1.0 for the total energy and pion scattering angle, respectively. The transition form factor of the $f_{0}(980)$ and that of the $f_{2}(1270)$ with the helicity-0,-1, and -2 components separately are measured for the first time and are compared with theoretical calculations.