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Register a new userResummed jet rates for heavy quark production in electron-positron annihilation
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Expressions for Sudakov form factors for heavy quarks are presented. They are used to construct resummed jet rates in electron-positron annihilation. Predictions are given for production of bottom quarks at LEP and top quarks at the Linear Collider.
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Expressions for Sudakov form factors for heavy quarks are presented. They are used to construct resummed jet rates in electron-positron annihilation. Predictions are given for production of bottom quarks at LEP and top quarks at the Linear Collider.
In this work we evaluate the cross section of the process $e^+e^-to J/psi eta_c$ at energy $sqrt{s}approx 10.6$ GeV in the Bethe-Salpeter formalism. To simplify our calculation, the heavy quark limit is employed. Without taking the beyond-leading-order contribution(s) into account, the cross section calculated in this scenario is comparable with the experimental data. We also present our prediction for the cross section of double bottomonium production $e^+e^-to Upsilon(1S)eta_b$ for the energy range of $sqrt{s}approx (25 hbox{-} 30)$ GeV which may be experimentally tested, even though there is no facility of this range available at present yet.
In this work we study the e^{+}e^{-}tophi K^{+}K^{-} reaction. The leading order electromagnetic contributions to this process involve the gamma*phi K^{+}K^{-} vertex function with a highly virtual photon. We calculate this function at low energies using Rchi PT supplemented with the anomalous term for the VVP interactions. Tree level contributions involve the kaon form factors and the K*K transition form factors. We improve this result, valid for low photon virtualities, replacing the lowest order terms in the kaon form factors and K*K transition form factors by the form factors as obtained in Uchi PT in the former case and the ones extracted from recent data on e^{+}e^{-}to KK* in the latter case. We calculate rescattering effects which involve meson-meson amplitudes. The corresponding result is improved using the unitarized meson-meson amplitudes containing the scalar poles instead of the lowest order terms. Using the BABAR value for BR(Xto phi f_{0})Gamma (Xto e^{+} e^{-}), we calculate the contribution from intermediate X(2175). A good description of data is obtained in the case of destructive interference between this contribution and the previous ones, but more accurate data on the isovector K*K transition form factor is required in order to exclude contributions from an intermediate isovector resonance to e^{+}e^{-}to phi K^{+}K^{-} around 2.2 GeV.
We calculate the cross section for the exclusive production of J^{PC}=0^{++} glueballs G_0 in association with the J/psi in e^+e^- annihilation using the pQCD factorization formalism. The required long-distance matrix element for the glueball is bounded by CUSB data from a search for resonances in radiative Upsilon decay. The cross section for e^+e^- -> J/psi+ G_0 at sqrt{s}=10.6 GeV is similar to exclusive charmonium-pair production e^+e^- -> J/psi+h for h=eta_c and chi_{c0}, and is larger by a factor 2 than that for h=eta_{c}(2S). As the subprocesses gamma^* -> (c c-bar) (c c-bar) and gamma^* -> (c c-bar) (g g) are of the same nominal order in perturbative QCD, it is possible that some portion of the anomalously large signal observed by Belle in e^+ e^- -> J/psi X may actually be due to the production of charmonium-glueball J/psi G_J pairs.
Process of muon (pion) pair production with small invariant mass in the electron-positron high-energy annihilation, accompanied by emission of hard photon at large angles, is considered. We find that the Dell-Yan picture for differential cross section is valid in the charge-even experimental set-up. Radiative corrections both for electron block and for final state block are taken into account.
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