arXiv subjects

Li-Kun Hao

Publications and source records attributed to Li-Kun Hao.

5 recordsLinked to original sources

arXiv2002

D-wave Charmonium Production in $e^+e^-$ Annihilation at $\sqrt{s}=10.6$ GeV

We calculate the D-wave charmonium production in $e^+e^-$ annihilation at BELLE and BABAR at $\sqrt{s}=10.6$ GeV using the nonrelativistic QCD factorization formalism, including color singlet and color octet contributions. We analyze the contributions of various processes for $δ_J(J=1,2)$ production. We find that both the color singlet and color octet channels may give substantial contributions, and the production rates are estimated to be $σ(δ_1)\simeq 0.043-0.16pb$ and $σ(δ_2)\simeq 0.094-0.29pb$, which, however, are very sensitive to the choice of the color octet matrix elements of the D-wave charmonium states. The measurement of D-wave charmonium production at BABAR and BELLE in the future will be very helpful to test the color octet mechanism and to determine the color octet matrix elements.

hep-ph↗

arXiv2002

Charmonium Production in $e^+e^-$ Annihilation at $\sqrt{s}=10.6GeV$

We review the charmonium production in $e^+e^-$ annihilation at $\sqrt{s}=10.6GeV$. NRQCD predictions for the $J/ψ$ production are compared with the recent measurements by BaBar and Belle. A NRQCD calculation for the $D$-wave charmonium production is reported to further test the color-octet mechanism and detect the $J^{PC}=2^{--}$ state. The issue of double $c \bar c$ production in $e^+e^-$ annihilation observed by Belle is also discussed.

hep-ph↗

arXiv2000

Inelastic electroproduction of $η_c$ at ep colliders

Using the nonrelativistic QCD factorization formalism, we calculate the electroproduction cross sections of $η_c$ in ep collisions, including the contribution from both the transverse photon and the longitudinal photon. For this process the color-singlet contribution vanishes up to the next to leading order perturbative QCD calculations. The dominant contribution comes from the color-octet ${}^1S_0^{(8)}$ subprocess. The nonperturbative color-octet matrix element of ${}^1S_0^{(8)}$ of $η_c$ is related to that of ${}^3S_1^{(8)}$ of $J/ψ$ by heavy quark spin symmetry, and the latter can be determined from the direct production of $J/ψ$ at large transverse momentum at the Fermilab Tevatron. The measurement of this process at DESY HERA can be viewed as another independent test for the color-octet production mechanism

hep-ph↗

arXiv1999

Inelastic $J/ψ$ production in polarized photon-hadron collisions

Presented here is a calculation of inelastic $J/ψ$ production in polarized photon-hadron collisions under the framework of NRQCD factorization formalism. We consider the photoproduction of $\jpsi$ in the energy range relevant to HERA. The Weizsäcker-Williams approximation is adopted in the evaluation of the cross sections for $ep$ collisions. We found that this process can give another independent test for the color-octet mechanism, and the different features for the two color-octet processes may provide further informations on the mechanism for inelastic $\jpsi$ photoproduction. And the discrepancy on the production asymmetry $A$ between various sets of polarized gluon distribution functions is also found to be distinctive.

hep-ph↗

arXiv1999

Photoproduction of $η_c$ in NRQCD

We present a calculation for the photoproduction of $η_c$ under the framework of NRQCD factorization formalism. We find a quite unique feature that the color-singlet contribution to this process vanishes at not only the leading order but also the next to leading order perturbative QCD calculations and that the dominant contribution comes from the color-octet ${}^1S_0^{(8)}$ subprocess. The nonperturbative color-octet matrix element of ${}^1S_0^{(8)}$ of $η_c$ is related to that of ${}^3S_1^{(8)}$ of $J/ψ$ by the heavy quark spin symmetry, and the latter can be determined from the direct production of $J/ψ$ at large transverse momentum at the Fermilib Tevatron. We then conclude that the measurement of this process may clarify the existing conflict between the color-octet prediction and the experimental result on the $J/ψ$ photoprodution.

hep-ph↗