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Register a new userStudy of the $psi_2(3823)$ and $chi_{c1}(3872)$ states in $B^+ rightarrow left( Jpsipi^+pi^-right)K^+$ decays
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The decays $B^+rightarrow J/psi pi^+ pi^- K^+$ are studied using a data set corresponding to an integrated luminosity of 9fb$^{-1}$ collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate $psi_2(3823)$, $chi_{c1}(3872)$ and $psi(2S)$ states are reported. The decay of $B^+rightarrow psi_2(3872)K^+$ with $psi_2(3823)rightarrow Jpsipi^+pi^-$ is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the $psi_2(3823)$, $chi_{c1}(3872)$ and $psi(2S)$ states are measured to be $$ begin{array}{rcl} m_{chi_{c1(3872)}} - m_{psi_2(3823)} &= & 47.50 pm 0.53 pm 0.13,mathrm{MeV/}c^2,, m_{psi_2(3823)} - m_{psi(2S)} &= & 137.98 pm 0.53 pm 0.14,mathrm{MeV/}c^2,, m_{chi_{c1}(3872)} - m_{psi(2S)} &= & 185.49 pm 0.06 pm 0.03,mathrm{MeV/}c^2,, end{array} $$ resulting in the most precise determination of the $chi_{c1}(3782)$ mass. The width of the $psi_2(3823)$ state is found to be below 5.2MeV at 90% confidence level. The Breit-Wigner width of the $chi_{c1}(3872)$ state is measured to be $$ Gamma^{mathrm{BW}}_{chi_{c1}(3872)} = 0.96^{+0.19}_{-0.18}pm0.21 mathrm{MeV},$$ which is inconsistent with zero by 5.5 standard deviations.
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A search is made for the highly-suppressed B meson decays $B^{+}rightarrow K^{+}K^{+}pi^{-}$ and $B^{+}rightarrow pi^{+}pi^{+}K^{-}$ using a data sample corresponding to an integrated luminosity of 3.0 $fb^{-1}$ collected by the LHCb experiment in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. No evidence is found for the decays, and upper limits at 90% confidence level are determined to be $mathcal{B}(B^{+}rightarrow K^{+}K^{+}pi^{-}) < 1.1times 10^{-8}$ and $mathcal{B}(B^{+}rightarrow pi^{+}pi^{+}K^{-}) < 4.6times 10^{-8}$.
We report a search for $X(3872)$ and $X(3915)$ in $B^+ to chi_{c1} pi^0 K^+$ decays. We set an upper limit of $mathcal{B}(B^+ to X(3872) K^+) times mathcal{B}(X(3872) to chi_{c1} pi^0)$ $ < 8.1 times 10^{-6}$ and $mathcal{B}(B^+ to X(3915) K^+) times mathcal{B}(X(3915) to chi_{c1} pi^0)$ $ < 3.8 times 10^{-5}$ at 90% confidence level. We also measure $mathcal{B}(X(3872) to chi_{c1} pi^0)/mathcal{B}(X(3872) to J/psi pi^+ pi^-) < 0.97$ at 90% confidence level. The results reported here are obtained from $772 times 10^{6}$ $Boverline{B}$ events collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.
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 $$ m_{B^0_s} = 5366.98 pm 0.07 pm 0.13,{mathrm{MeV}}/c^2,. $$
A study of the lineshape of the $chi_{c1}(3872)$ state is made using a data sample corresponding to an integrated luminosity of $3,$fb$^{-1}$ collected in $pp$ collisions at centre-of-mass energies of 7 and 8,TeV with the LHCb detector. Candidate $chi_{c1}(3872)$ and $psi(2S)$ mesons from b-hadron decays are selected in the $ J/psi pi^+ pi^-$ decay mode. Describing the {mbox{lineshape}} with a Breit--Wigner function, the mass splitting between the $chi_{c1}(3872)$ and $psi(2S)$ states, $Delta m$, and the width of the $chi_{c1}(3872)$ state, $Gamma_{mathrm{BW}}$, are determined to be begin{eqnarray*} Delta m & = & 185.598 pm 0.067 pm 0.068, mathrm{MeV} ,, Gamma_{mathrm{BW}} & = & phantom{00}1.39phantom{0} pm 0.24phantom{0} pm 0.10phantom{0} mathrm{MeV} ,, end{eqnarray*} where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be begin{eqnarray*} mathrm{mode} & = 3871.69^{,+,0.00,+,0.05}_{,-,0.04,-,0.13} &mathrm{MeV} mathrm{FWHM} & = 0.22^{,+,0.07,+,0.11}_{,-,0.06,-,0.13}& mathrm{MeV} . end{eqnarray*} An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasi-bound $D^0bar{D}^{*0}$ state but a quasi-virtual state is still allowed at the level of $2$ standard deviations.
Using a total of $9.0~mathrm{fb}^{-1}$ of $e^+e^-$ collision data with center-of-mass energies between 4.15 and 4.30 GeV collected by the BESIII detector, we search for the processes $e^+e^-to gamma X(3872)$ with $X(3872)topi^0chi_{cJ}$ for $J=0,1,2$. We report the first observation of $X(3872)topi^{0}chi_{c1}$, a new decay mode of the $X(3872)$, with a statistical significance of more than 5$sigma$. Normalizing to the previously established process $e^+e^-to gamma X(3872)$ with $X(3872)topi^+pi^-J/psi$, we find ${cal B}(X(3872) to pi^0 chi_{c1})/{cal B}(X(3872) to pi^+pi^- J/psi) = 0.88^{+0.33}_{-0.27}pm0.10$, where the first error is statistical and the second is systematic. We set 90% confidence level upper limits on the corresponding ratios for the decays to $pi^0chi_{c0}$ and $pi^0chi_{c2}$ of 19 and 1.1, respectively.
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