相关论文: The Photon Spectrum in Upsilon Decays
The Operator Product Expansion, in conjunction with the power counting of non-relativistic field theory, is used to examine the end-point region of the radiative decay of heavy quark bound states with $^3S_1$ quantum numbers,…
We analyze the end-point region of the photon spectrum in semi-inclusive radiative decays of very heavy quarkonium (m alpha_s^2 >> Lambda_QCD). We discuss the interplay of the scales arising in the Soft-Collinear Effective Theory, m,…
Motivated by very recent measurement of the radiative decays of $\Upsilon(1S)$ to $\chi_{c1}$ at Belle, we use the nonrelativistic QCD factorization theory and calculate the branching fractions of the radiative decays of bottomonium into…
The photon spectrum in the inclusive electromagnetic radiative decays of the $B$ meson, $B \to X_{s} \gamma$ plus $B \to X_{d} \gamma$, is studied using a data sample of $(382.8 \pm 4.2) \times 10^6$ $\Upsilon(4S) \to B\overli\ ne{B}$…
Recently, Neubert has suggested that a certain class of nonperturbative corrections dominates the shape of the electron spectrum in the endpoint region of semileptonic $B$ decay. Perturbative QCD corrections are important in the endpoint…
Calculations for inclusive J/psi production in Upsilon decay through the color-octet mechanisms b\bar b[^3S_1, 1] -> c \bar c[^{2s+1}L_J, 8] + g are presented. It is shown that these O(alpha^5_sv^4_c) contributions compete with other…
We review the theoretical understanding of the branching ratio and photon-energy spectrum in B -> Xs gamma decays at next-to-leading order in QCD, including consistently the effects of Fermi motion. For the Standard Model, we obtain B(B ->…
We present an improved measurement of the $\eta'$ meson energy spectrum in $\Upsilon(1S)$ decays, using 1.2 fb^{-1} of data taken at the $\Upsilon(1S)$ center-of-mass energy with the CLEO III detector. We compare our results with models of…
Using a combination of the operator product and heavy quark expansions, we resum the leading nonperturbative contributions to the inclusive photon spectrum in $B\to X_s\,\gamma$ decays. The shape of the spectrum is determined by a universal…
The photon spectrum in B->X_{s,d} \gamma decay, where X_s(d) is any strange (non-strange) hadronic state, is studied using data samples of $e^+e^- \rightarrow \Upsilon(4S) \to B B-bar decays collected by the Babar and Belle experiments.…
We present an improved measurement of the eta' meson energy spectrum in Upsilon(1S) decays, using 1.2 fb^{-1}} of data taken at the Upsilon(1S) center-of-mass energy with the CLEO III detector. We compare our results with models of eta'…
We consider the inclusive radiative decays quarkonium -> gamma + hadrons and examine the effects of soft QCD radiation on the photon energy spectrum near the endpoint.
I this talk I give an introduction to the soft collinear effective theory by considering in detail the decay rate for $B \to X_s \gamma$ near the endpoint.
Using data taken with the CLEO-c detector at the Cornell Electron Storage Ring, we have investigated the direct photon momentum spectrum in the decay J/psi->gamma+gluon+gluon, via the 'tagged' process: e+e- -> psi(2S); psi(2S)->J/psi…
It is argued that the dominant subleading shape-function contributions to the endpoint region of the charged-lepton energy spectrum in B -> X_u l nu decays can be related in a model-independent way to an integral over the B -> X_s gamma…
We report on a search for the radiative decay of Upsilon(1S) to the pseudoscalar mesons eta and etaprime in 21.2 +/- 0.2 times 10^6 Upsilon(1S) decays collected with the CLEO III detector at the Cornell Electron Storage Ring (CESR). The eta…
We study radiative decays of $\Upsilon$ to light quark jets in nonrelativistic QCD by taking both the color singlet and color octet $b\bar b$ operators into consideration. The cut for quark jet energy and cut for the angle between two quark…
The rare decay $B\rightarrow A\gamma$, with $A$ representing axial-vector mesons such as $K_1 (1270),\; K_1 (1400),\; b_1(1300),\; a_1(1260)$, is studied at next-to-leading order (NLO) in soft collinear effective theory (SCET). The large…
In this work, we investigate the characteristics of the spin-singlet state $\eta_b$ of the bottomonia family via the radiative decays of $\Upsilon(nS)\to \eta_b+\gamma$. The theoretical estimation of the decay widths is carried out in terms…
We investigate the theoretical uncertainties of $P$-wave charmonium decays into two pions, $\chi_{\c J}\rightarrow \pi^+\pi^-$, $\pi^0\pi^0$. Constraining the pion distribution-amplitude from the recent precise data on $F_{\pi\gamma}(Q^2)$,…