Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userObservation of $Upsilon(4S)to eta Upsilon(1S)$
77
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report the first observation of the hadronic transition $Upsilon(4S)toetaUpsilon(1S)$, using 496 fb$^{-1}$ data collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. We reconstruct the $eta$ meson through its decays to $rho^0gamma$ and to $pi^+pi^-eta$, with $etatogammagamma$. We measure: ${cal B}(Upsilon(4S)toetaUpsilon(1S))=(3.43pm 0.88 {rm(stat.)} pm 0.21 {rm(syst.)})times10^{-5}$, with a significance of 5.7$sigma$.
rate research
Read More
The decays of $Upsilon(1s)togamma(eta,eta)$ are studied by an approach which has successfully predicted the ratio $frac{Gamma(J/psitogammaeta)}{Gamma(J/psitogammaeta)}$. Strong dependence on quark mass has been found in the decays $(J/psi, Upsilon(1s))togamma(eta,eta)$. Very small decay rates of $Upsilon(1s)togamma(eta,eta)$ are predicted.
The dipion transitions $Upsilon(2S,3S,4S) to Upsilon(1S,2S)pipi$ are systematically studied by considering the mechanisms of the hadronization of soft gluons, exchanging the bottomoniumlike $Z_b$ states, and the bottom-meson loops. The strong pion-pion final-state interaction, especially including the channel coupling to $Kbar{K}$ in the $S$-wave, is taken into account in a model-independent way using the dispersion theory. Through fitting to the available experimental data, we extract values of the transition chromopolarizabilities $|alpha_{Upsilon(mS)Upsilon(nS)}|$, which measure the chromoelectric couplings of the bottomonia with soft gluons. It is found that the $Z_b$ exchange has a slight impact on the extracted chromopolarizablity values, and the obtained $|alpha_{Upsilon(2S)Upsilon(1S)}|$ considering the $Z_b$ exchange is $(0.29pm 0.20)~text{GeV}^{-3}$. Our results could be useful in studying the interactions of bottomonium with light hadrons.
Using samples of 102 million $Upsilon(1S)$ and 158 million $Upsilon(2S)$ events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the three-body final states $phi K^+ K^-$, $omega pi^+ pi^-$ and $K^{ast 0}(892) K^- pi^+ $, and to the two-body Vector-Tensor ($phi f_2(1525)$, $omega f_2(1270)$, $rho a_2(1320)$ and $K^{ast 0}(892) bar{K}_2^{ast 0}(1430) $) and Axial-vector-Pseudoscalar ($K_1(1270)^+ K^-$, $K_1(1400)^+ K^- $ and $b_1(1235)^+ pi^- $) pairs. Signals are observed for the first time in the $Upsilon(1S) to phi K^+ K^-$, $omega pi^+ pi^-$, $K^{ast 0} K^- pi^+$, $K^{ast0} K_2^{ast 0}$ and $Upsilon(2S) to phi K^+ K^-$, $K^{ast 0} K^- pi^+$ decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance less than $3sigma$. The ratios of the branching fractions of $Upsilon(2S)$ and $Upsilon(1S)$ decays into the same final state are used to test a perturbative QCD prediction for OZI suppressed bottomonium decays.
Using a sample of $771.6 times 10^{6}$ $Upsilon(4S)$ decays collected by the Belle experiment at the KEKB $e^+e^-$ collider, we observe for the first time the transition $Upsilon(4S) to eta h_b(1P)$ with the branching fraction ${cal B}[Upsilon(4S) to eta h_b(1P)]= (2.18 pm 0.11 pm 0.18) times 10^{-3}$ and we measure the $h_b(1P)$ mass $M_{h_{b}(1P)} = (9899.3 pm 0.4 pm 1.0)$ MeV/$c^{2}$, corresponding to the hyperfine splitting $Delta M_{mathrm HF}(1P) = (0.6 pm 0.4 pm 1.0)$ MeV/$c^{2}$. Using the transition $h_b(1P) to gamma eta_b(1S)$, we measure the $eta_b(1S)$ mass $M_{eta_{b}(1S)} = (9400.7 pm 1.7 pm 1.6)$ MeV/$c^{2}$, corresponding to $Delta M_{mathrm HF}(1S) = (59.6 pm 1.7 pm 1.6)$ MeV/$c^{2}$, the $eta_b(1S)$ width $Gamma_{eta_{b}(1S)} = (8 ^{+6}_{-5} pm 5)$ MeV/$c^{2}$ and the branching fraction ${cal B}[h_b(1P) to gamma eta_b(1S)]= (56 pm 8 pm 4) %$.
Using data collected in the Belle experiment at the KEKB asymmetric-energy $e^+e^-$ collider we search for transitions $Upsilon(4S) rightarrow eta_b(1S)omega$, $Upsilon(5S) rightarrow eta_b(1S)omega$ and $Upsilon(5S) rightarrow eta_b(2S)omega$. No significant signals are observed and we set 90% confidence level upper limits on the corresponding visible cross sections: $0.2 ~textrm{pb}, 0.4 ~textrm{pb}$ and $1.9 ~textrm{pb}$, respectively.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
