Sure, you could postulate some entirely independent, unconnected
something, that continues after a physical death - but if it is at any time and in any way connected to, or interacting with, the physical body (e.g. brain), then - no; if it interacts, it's accessible to empirical enquiry, if it doesn't, then by definition, it's not part of 'you', the owner of the body that dies.
It's the 'interaction problem'. We know what the brain is made of - protons, neutrons, & electrons, and we know how they interact with each other and other particles, and we know what forces they are affected by and at what range (at biological scales, electromagnetism and gravity). Anything that can affect, or is affected by, the brain and its functioning, is detectable by that very interaction, and so is accessible to empirical enquiry. If it isn't accessible to empirical enquiry, it has no detectable effects on the physical world, which means it has no significant interactions with the physical world (at human scales). Sean Carroll explains more clearly here: '
The Higgs Boson and the Nature of Reality'....