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Register a new userSearch for the rare decays $J/psi to D_s^-rho^+$ and $J/psi to overline{D}{}^0overline{K}{}^{ast0}$
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A search for the rare decays of $J/psi to D_s^-rho^+ + c.c.$ and $J/psi to overline{D}{}^0overline{K}{}^{ast0} + c.c.$ is performed with a data sample of 225.3 million $J/psi$ events collected with the BESIII detector. No evident signal is observed. Upper limits on the branching fractions are determined to be $mathcal{B}(J/psi to D_s^-rho^+ + c.c.) < 1.3 times 10^{-5}$ and $mathcal{B}(J/psi to overline{D}{}^0overline{K}{}^{ast0} + c.c.) < 2.5 times 10^{-6}$ at the $90%$ confidence level.
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A search for the rare decay of a $B^{0}$ or $B^{0}_{s}$ meson into the final state $J/psigamma$ is performed, using data collected by the LHCb experiment in $pp$ collisions at $sqrt{s}=7$ and $8$ TeV, corresponding to an integrated luminosity of 3 fb$^{-1}$. The observed number of signal candidates is consistent with a background-only hypothesis. Branching fraction values larger than $1.7times 10^{-6}$ for the $B^{0}to J/psigamma$ decay mode are excluded at 90% confidence level. For the $B^{0}_{s}to J/psigamma$ decay mode, branching fraction values larger than $7.4times 10^{-6}$ are excluded at 90% confidence level, this is the first branching fraction limit for this decay.
Using the data samples of $(1310.6pm7.2 )times 10^{6}$ $J/psi$ events and $(448.1pm2.9)times 10^{6}$ $psi(3686)$ events collected with the BESIII detector, we search for the rare decays $J/psi to D^{0} e^{+}e^{-} +c.c.$ and $psi(3686) to D^{0} e^{+}e^{-} +c.c.$. No significant signals are observed and the corresponding upper limits on the branching fractions at the $90%$ confidence level are determined to be $Br(J/psi to D^{0} e^{+}e^{-} +c.c.)< 8.5times 10^{-8}$ and $Br (psi(3686) to D^{0} e^{+}e^{-} +c.c.)<1.4times 10^{-7}$, respectively. Our limit on $Br(J/psi to D^{0} e^{+}e^{-} +c.c.)$ is more stringent by two orders of magnitude than the previous results, and the $Br(psi(3686) to D^{0} e^{+}e^{-} +c.c.)$ is measured for the first time.
A search for the decays $B_c^+ to J/psi D^{(*)0} K^+$ and $B_c^+ to J/psi D^{(*)+} K^{*0}$ is performed with data collected at the LHCb experiment corresponding to an integrated luminosity of 3 fb$^{-1}$. The decays $B_c^+ to J/psi D^0 K^+$ and $B_c^+ to J/psi D^{*0} K^+$ are observed for the first time, while first evidence is reported for the $B_c^+ to J/psi D^{*+} K^{*0}$ and $B_c^+ to J/psi D^+ K^{*0}$ decays. The branching fractions of these decays are determined relative to the $B_c^+ to J/psi pi^+$ decay. The $B_c^+$ mass is measured, using the $J/psi D^0 K^+$ final state, to be $6274.28 pm 1.40 (stat) pm 0.32 (syst)$ MeV/$c^2$. This is the most precise single measurement of the $B_c^+$ mass to date.
The results of searches for $B^{0}_{(s)} rightarrow J/{psi} p overline{p}$ and $B^{+} to J/{psi} p overline{p} {pi}^{+}$ decays are reported. The analysis is based on a data sample, corresponding to an integrated luminosity of 1.0 fb$^{-1}$ of $pp$ collisions, collected with the LHCb detector. An excess with 2.8$,sigma$ significance is seen for the decay $B^{0}_{s} to J/{psi} p overline{p}$ and an upper limit on the branching fraction is set at the 90 % confidence level: ${cal B}(B^{0}_{s} to J/{psi} p overline{p}) < 4.8 times 10^{-6}$, which is the first such limit. No significant signals are seen for $B^{0} to J/{psi} p overline{p}$ and $B^{+} to J/{psi} p overline{p} {pi}^{+}$ decays, for which the corresponding limits are set: ${cal{B}}(B^{0} to J/{psi} p overline{p}) < 5.2 times 10^{-7}$, which significantly improves the existing limit; and ${cal{B}}(B^{+} to J/{psi} p overline{p} {pi}^{+}) < 5.0 times 10^{-7}$, which is the first limit on this branching fraction.
The data sample of $Lambda_b^0to J/psi p K^-$ decays acquired with the LHCb detector from 7 and 8~TeV $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$, is inspected for the presence of $J/psi p$ or $J/psi K^-$ contributions with minimal assumptions about $K^- p$ contributions. It is demonstrated at more than 9 standard deviations that $Lambda_b^0to J/psi p K^-$ decays cannot be described with $K^- p$ contributions alone, and that $J/psi p$ contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for $P_c^+to J/psi p$ charmonium-pentaquark states in the same data sample.
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