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C. Q. Geng

Publications and source records attributed to C. Q. Geng.

113 records · Page 7Linked to original sources
arXiv1995

Comments on long distance contribution to $K^+\toπ^+ν\barν$

We study the long distance contribution to $K^+\toπ^+ν\bar{ν$ by using chiral perturbation theory. We find that the tree level $O(P^2)$ contribution vanishes identically without assuming the large $N_c$ limit. The leading contribution arises from the one-loop amplitude, which is $O(P^4)$ in the chiral power counting. The branching ratio of the long distance contribution is found to be of order $10^{-7}$ smaller compared with that of short distance one and hence is completely negligible.

hep-ph↗
arXiv1995

Axion-photon Couplings in Invisible Axion Models

We reexamine the axion-photon couplings in various invisible axion models motivated by the recent proposal of using optical interferometry at the ASST facility in the SSCL to search for axion. We illustrate that the assignment of $U(1)_{PQ}$ charges for the fermion fields plays an important role in determining the couplings. Several simple non-minimal invisible axion models with suppressed and enhanced axion-photon couplings are constructed, respectively. We also discuss the implications of possible new experiments to detect solar axions by conversion to $X$-rays in a static magnetic apparatus tracking the sun.

hep-ph↗
arXiv1994

CP Conserving and Violating Contributions to $K_L\toπ^+π^-ν\barν$

We study both CP conserving and violating contributions to the decay $K_L\toπ^+π^-ν\barν$. We find that the decay branching ratio is dominated by the CP conserving part. In the standard CKM model, we estimate that for $m_t\sim 174\ GeV$, the branching ratio due to the CP conserving (violating) contributions can be as large as $4.4 \times 10^{-13}$ ($1.0\times 10^{-14}$).

hep-ph↗
arXiv1993

Right-handed Neutral Currents, Families and the LEP $l^+l^-γγ$ Events

We explore the possibility of having new physics which could account for the $l^+l^-γγ$ events with $M_{γγ}\simeq 60\ $GeV recently reported by LEP. We consider models which contain an extra neutral gauge boson ($Z'$) that couples only to right-handed fermions. The models naturally require at least three quark and lepton families from anomaly cancellation. We find simple realizations of such models that have $\ell^+\ell^-γγ$ events at a rate similar to that observed at LEP.

hep-ph↗