A one-parameter regularization freedom of the Hamiltonian constraint for loop quantum gravity is analyzed. The corresponding spatially flat, homogenous and isotropic model includes the two well-known models of loop quantum cosmology as special cases. The quantum bounce nature is tenable in the generalized cases. For positive value of the regularization parameter, the effective Hamiltonian leads to an asymptotic de-Sitter branch of the Universe connecting to the standard Friedmann branch by the quantum bounce. Remarkably, by suitably choosing the value of the regularization parameter, the observational cosmological constant can emerge at large volume limit from the effect of quantum gravity, and the effective Newtonian constant satisfies the experimental restrictions in the meantime.

分析了圈量子引力哈密顿约束的一参数正则化自由度。相应的空间平坦、同质和各向同性模型包括两个著名的圈量子宇宙学模型作为特例。量子反弹性质在广义情况下是站得住脚的。对于正则化参数的正值，有效哈密顿量导致宇宙的渐近去西特分支通过量子反弹连接到标准弗里德曼分支。Remarkably, by suitably choosing the value of the regularization parameter, the observational cosmological constant can emerge at large volume limit from the effect of quantum gravity, and the effective Newtonian constant satisfies the experimental restrictions in the meantime.