We report a search for $B^{0}to eta eta $ with a data sample corresponding to an integrated luminosity of $698 ,{rm fb}^{-1}$ containing $753 times 10^{6}$ $Bbar{B}$ pairs collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The branching fraction is measured to be $mathcal{B}(B^{0} to eta eta ) = (7.6^{+2.7 +1.4}_{-2.3 -1.6}) times 10^{-7}$ at the level of 3.3 standard deviations above zero, which provides the first evidence for the decay $B^{0} to eta eta$.
We report a search for the charmless hadronic decay $B^0toeta pi^0$ with a data sample corresponding to an integrated luminosity of 694 $rm fb^{-1}$ containing $753times10^6$ $Bbar{B}$ pairs. The data were collected by the Belle experiment running on the $Upsilon(4S)$ resonance at the KEKB $e^+e^-$ collider. We measure a branching fraction $mathcal{B}(B^0toetapi^0)=(4.1^{+1.7+0.5}_{-1.5-0.7})times 10^{-7}$, where the first uncertainty is statistical and the second is systematic. Our measurement gives an upper limit of $mathcal{B}(B^0toetapi^0)<6.5times 10^{-7}$ at 90% confidence level. The signal has a significance of $3.0$ standard deviations and constitutes the first evidence for this decay mode.
We report a search for charmless hadronic decays of neutral $B$ mesons to $eta K^{*}(892)^{0}$. The results are based on a 711fb$^{-1}$ data sample that contains $772times 10^6 Boverline{B}$ pairs, collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+e^-$ collider. We observe the decay for the first time with a significance of 5.0 standard deviations and obtain its branching fraction ${cal B}[B^0toeta K^{*}(892)^{0}]=[2.6pm0.7{rm (stat)}pm0.2{rm (syst)}]times 10^{-6}$. We also measure the $CP$ violating asymmetry as ${cal A}_{CP}[B^0toeta K^{*}(892)^{0}]=-0.22pm0.29{rm (stat)}pm0.07{rm syst}$.
A search for the charmless $B^{0}_{s} to eta^{prime}phi$ decay is performed using $pp$ collision data collected by the LHCb experiment at centre-of-mass energies of $7$ and $8$ TeV, corresponding to an integrated luminosity of 3 fb$^{-1}$. No signal is observed and upper limits on the $B^{0}_{s} to eta^{prime}phi$ branching fraction are set to $0.82times 10^{-6}$ at $90%$ and $1.01times 10^{-6}$ at $95%$ confidence level.
We report the results of the first search for the decay $B_s^0 rightarrow eta^prime eta$ using $121.4~textrm{fb}^{-1}$ of data collected at the $Upsilon(5S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe no significant signal and set a 90% confidence-level upper limit of %$7.1 times 10^{-5}$ $6.5 times 10^{-5}$ on the branching fraction of this decay.
In the Standard Model (SM) charmless hadronic decays $B_s^0 rightarrow eta^prime eta$ proceed via tree-level $bto u$ and penguin $bto s$ transitions. Penguin transitions are sensitive to Beyond-the-Standard-Model (BSM) physics scenarios and could affect the branching fractions and {it CP} asymmetries in such decays. Once branching fractions for two-body decays $B_s to etaeta, etaeta^{prime}, eta^{prime}eta^{prime} $ are measured, and the theoretical uncertainties are reduced, it would be possible to extract {it CP} violating parameters from the data using the formalism based on SU(3)/U(3) symmetry. To achieve this goal, at least four of these six branching fractions need to be measured. Only the branching fraction for $B_s^0 to eta^{prime}eta^{prime}$ has been measured so far.