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Register a new userObservation and Spin-Parity Determination of the $X(1835)$ in $J/psirightarrowgamma K^0_S K^0_Seta$
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We report an observation of the process $J/psirightarrowgamma X(1835)rightarrowgamma K^0_S K^0_Seta$ at low $K^0_S K^0_S$ mass with a statistical significance larger than 12.9$sigma$ using a data sample of $1.31 times 10^{9}$ $J/psi$ events collected with the BESIII detector. In this region of phase space the $K^0_S K^0_S$ system is dominantly produced through the $f_0(980)$. By performing a partial wave analysis, we determine the spin-parity of the $X(1835)$ to be $J^{PC}=0^{-+}$. The mass and width of the observed $X(1835)$ are $1844pm9(text{stat})^{+16}_{-25}(text{syst})$~MeV~and $192^{+20}_{-17}(text{stat})^{+62}_{-43}(text{syst})$~MeV, respectively, which are consistent with the results obtained by BESIII in the channel $J/psirightarrowgammapi^+pi^-eta^{prime}$.
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The decays $B^0_s rightarrow J/psi pi^+pi^- K^+ K^-$ are studied using a data set corresponding to an integrated luminosity of 9fb$^{-1}$, collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13TeV. The decays $B^0_s rightarrow J/psi K^{ast0} bar{K}^{ast0}$ and $B^0_s rightarrow chi_{c1}(3872)K^+K^-$, where the $K^+K^-$ pair does not originate from a $phi$ meson, are observed for the first time. Precise measurements of the ratios of branching fractions between intermediate $chi_{c1}(3872)phi$, $J/psi K^{ast0}bar{K}^{ast0}$, $psi(2S)phi$ and $chi_{c1}(3872)K^+K^-$ states are reported. A structure, denoted as $X(4740)$, is observed in the $J/psiphi$ mass spectrum and, assuming a Breit-Wigner parameterisation, its mass and width are determined to be begin{eqnarray*} m_{X(4740)} & = & 4741 pm 6 pm 6,{mathrm{MeV}}/c^2 ,, Gamma_{X(4740)} & = & 53 pm 15 pm 11,{mathrm{MeV}} ,, end{eqnarray*} where the first uncertainty is statistical and the second is systematic. In addition, the most precise single measurement of the mass of the $B^0_s$ meson is performed and gives a value of $$ m_{B^0_s} = 5366.98 pm 0.07 pm 0.13,{mathrm{MeV}}/c^2,. $$
The first observation of the decay $kstarkstar$ is reported using 35invpb of data collected by LHCb in proton-proton collisions at a centre-of-mass energy of 7 TeV. A total of $49.8 pm 7.5$ $B^0_s rightarrow (K^+pi^-)(K^-pi^+)$ events are {observed within $pm 50 mevcc$ of the Bs mass and $746 mevcc < m_{Kpi}< 1046 mevcc$, mostly coming from a resonant $kstarkstar$ signal.} The branching fraction and the CP-averaged Kstarz longitudinal polarization fraction are measured to be {$BR(kstarkstar) = (2.81 pm 0.46 ({rm stat.}) pm 0.45 ({rm syst.}) pm 0.34, (f_s/f_d))times10^{-5}$} and $f_L = 0.31 pm 0.12 ({rm stat.}) pm 0.04 ({rm syst.})$.
The first observation of the $B^0_stobar{D}^0 K^0_S$ decay mode and evidence for the $B^0_stobar{D}^{*0} K^0_S$ decay mode are reported. The data sample corresponds to an integrated luminosity of 3.0 $text{fb}^{-1}$ collected in $pp$ collisions by LHCb at center-of-mass energies of 7 and 8 TeV. The branching fractions are measured to be begin{align*} mathcal{B}(B^0_stobar{D}^0 bar{K}^0) &= (4.3pm0.5(text{stat})pm0.3(text{syst})pm0.3(text{frag})pm0.6(text{norm}))times10^{-4}, mathcal{B}(B^0_stobar{D}^{*0} bar{K}^0) &= (2.8pm1.0(text{stat})pm0.3(text{syst})pm0.2(text{frag})pm0.4(text{norm}))times10^{-4}, end{align*} where the uncertainties are due to contributions coming from statistical precision, systematic effects, and the precision of two external inputs, the ratio $f_s/f_d$ and the branching fraction of $B^0tobar{D}^0 K^0_S$, which is used as a calibration channel.
We study the processes $e^+ e^-to K^0_S K^0_Lpi^0gamma$, $K^0_S K^0_Letagamma$, and $K^0_S K^0_Lpi^0pi^0gamma$, where the photon is radiated from the initial state, providing cross section measurements for the hadronic final states over a continuum of center-of-mass energies. The results are based on 469~$fb^{-1}$ of data collected at or near the $Upsilon(4S)$~ resonance with the BaBar detector at SLAC. We present the first measurements of the $e^+ e^-to K^0_S K^0_Lpi^0$, $K^0_S K^0_Leta$, and $K^0_S K^0_Lpi^0pi^0$ cross sections up to a center-of-mass energy of 4~GeV, and study their intermediate resonance structures. We observe $J/psi$ decays to all of these final states for the first time, present measurements of their $J/psi$ branching fractions, and search for $psi(2S)$ decays.
The decay Bs -> J/psi K+ K- is investigated using 0.16/fb of data collected with the LHCb detector using 7 TeV pp collisions. Although the J/psi phi channel is well known, final states at higher K+K- masses have not previously been studied. In the K+K- mass spectrum we observe a significant signal in the f2(1525) region as well as a non-resonant component. After subtracting the non-resonant component, we find B(Bs->J/psi f_2(1525))/B(Bs->J/psi phi)=(26.4 +/- 2.7 +/- 2.4)%.
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