Dear Bhante,
I have found in other topic here (thanks to @llt) that in the Chinese Agamas, sammāsamādhi is not defined as the four jhānas, but as unification of mind (ekaggata). For example, in the SA 784 (Pali parallel of SN 45.8):
何等為正定？謂住心不亂，堅固攝持，寂止、三昧、一心
What is Right Samādhi? That is to say, abiding with the mind not scattered, firm and collected, with tranquility, samādhi, and unity of mind.
What is your opinion about the difference of definition of Right Samādhi between Pali Nikayas and Chinese Agamas? Does this indicate the practice of Right Samādhi is different among early Buddhist traditions?
Thank you 