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Register a new userEvidence for the h_b(1P) meson in the decay Upsilon(3S) --> pi0 h_b(1P)
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Using a sample of 122 million Upsilon(3S) events recorded with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we search for the $h_b(1P)$ spin-singlet partner of the P-wave chi_{bJ}(1P) states in the sequential decay Upsilon(3S) --> pi0 h_b(1P), h_b(1P) --> gamma eta_b(1S). We observe an excess of events above background in the distribution of the recoil mass against the pi0 at mass 9902 +/- 4(stat.) +/- 2(syst.) MeV/c^2. The width of the observed signal is consistent with experimental resolution, and its significance is 3.1sigma, including systematic uncertainties. We obtain the value (4.3 +/- 1.1(stat.) +/- 0.9(syst.)) x 10^{-4} for the product branching fraction BF(Upsilon(3S)-->pi0 h_b) x BF(h_b-->gamma eta_b).
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We report the first evidence for the eta_b(2S) using the h_b(2P)->eta_b(2S)gamma transition and the first observation of the h_b(1P)->eta_b(1S)gamma and h_b(2P)->eta_b(1S)gamma transitions. The mass and width of the eta_b(1S) and eta_b(2S) are measured to be m_etab(1S)=(9402.4+-1.5+-1.8)MeV/c^2, m_etab(2S)=(9999.0+-3.5 +2.8-1.9)MeV/c^2 and Gamma_etab(1S)=(10.8 +4.0-3.7 +4.5-2.0)MeV. We also update the h_b(1P) and h_b(2P) mass measurements. We use a 133.4/fb data sample collected at energies near the Upsilon(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
In this work, we study the contributions of the intermediate bottomoniumlike $Z_b$ states and the bottom meson loops in the heavy quark spin flip transitions $Upsilon(4S) to h_b(1P,2P) pi^+pi^-$. Depending on the constructive or destructive interferences between the $Z_b$-exchange and the bottom meson loops mechanisms, we predict two possible branching ratios for each process: BR$_{Upsilon(4S) to h_b(1P)pi^+pi^-}simeqbig(1.2^{+0.8}_{-0.4}times10^{-6}big)$ or $big( 0.5^{+0.5}_{-0.2}times10^{-6}big)$, and BR$_{Upsilon(4S) to h_b(2P)pi^+pi^-}simeq big(7.1^{+1.7}_{-1.1}times10^{-10}big)$ or $big( 2.4^{+0.2}_{-0.1}times10^{-10}big)$. The bottom meson loops contribution is found to be much larger than the $Z_b$-exchange contribution in the $Upsilon(4S) to h_b(1P) pipi$ transitions, while it can not produce decay rates comparable to the heavy quark spin conserved $Upsilon(4S) to Upsilon(1S,2S) pipi$ processes. We also predict the branch fractions of $psi(3S,4S) to h_c(1P)pi^+pi^-$ contributed from the charm meson loops.
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 ${cal B}[h_b(1P) to gamma eta_b(1S)]= (56 pm 8 pm 4) %$.
In this paper, we carry out the complete $mathcal O(alphaalpha_s^{2})$-order study on the inclusive productions of $Upsilon(nS)$ and $chi_b(nP)$ ($n=1,2,3$) via the Standard Model Higgs boson decay, within the framework of nonrelativistic QCD. The feeddown effects via the higher excited states are found to be substantial. The color-octet $^3S_1^{[8]}$ state related processes consisting of $H^0 to bbar{b}[^3S_1^{[8]}]+g$ and $H^0 to bbar{b}[^3S_1^{[8]}]+Q+bar{Q}$ ($Q=c,b$) play a vital role in the predictions on the decay widths. Moreover, our newly calculated next-to-leading order QCD corrections to $H^0 to bbar{b}[^3S_1^{[8]}]+g$ can enhance its leading-order result by 3-4 times, subsequently magnifying the total $^3S_1^{[8]}$ contributions by about $40%$. Such a remarkable enhancement will to a large extent influence the phenomenological conclusions. For the color-singlet $^3P_J^{[1]}$ state, in addition to $H^{0} to bbar{b}[^3P_J^{[1]}]+b+bar{b}$, the newly introduced light hadrons associated process, $H^{0} to bbar{b}[^3P_J^{[1]}]+g+g$, can also provide non-negligible contributions, especially for $^3P_2^{[1]}$. Summing up all the contributions, we have $mathcal B_{H^0 to chi_b(nP)+X} sim 10^{-6}-10^{-5}$ and $mathcal B_{H^0 to Upsilon(nS)+X} sim 10^{-5}-10^{-4}$, which meets marginally nowadays LHC experimental data and can help in understanding the heavy quarkonium production mechanism as well as the Yukawa couplings.
We report a study of radiative decays of chi_{bJ}(1P)(J=0,1,2) mesons into 74 hadronic final states comprising charged and neutral pions, kaons, protons; out of these, 41 modes are observed with at least 5 standard deviation significance. Our measurements not only improve the previous measurements by the CLEO Collaboration but also lead to first observations in many new modes. The large sample allows us to probe the total decay width of the chi_{b0}(1P). In the absence of a statistically significant result, a 90% confidence-level upper limit is set on the width at Gamma_{total}< 2.4 MeV. Our results are based on 24.7 fb^{-1} of e+e- collision data recorded by the Belle detector at the Upsilon(2S) resonance, corresponding to (157.8pm3.6)times10^6 Upsilon(2S) decays.
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