Recent content by Alpha2021

I am familiar with the process of calculating cross sections using tree-level Feynman diagrams. Currently, I'm keen on learning how to calculate the Feynman amplitude for a specific diagram displayed in the attached images. I'm wondering if there are any study materials available that offer a...

Thank you very much for your help.

Thanks for your kind reply. Definition of reduced Planck mass can be found here. The problem is that M_{Pl} is used in the literature interchangeably as Planck mass or reduced Planck mass. Did you see anywhere in Planck's papers where they define M_{Pl}?

What is the value of M_{Pl} used in the Planck (CMB) collaboration's observation papers, such as the one referenced in this link: https://arxiv.org/pdf/1807.06211.pdf. Specifically, I am wondering if it refers to the Planck mass or the reduced Planck mass?

Thanks a lot for this kind reply. The pages numbers saved my time to find the chapter. (sorry for the late reply. Are you saying that violation of conditions ε, η≈1 can be called a graceful exit of inflation (slow roll)? Is it sufficient?

How to determine whether a cosmological inflation model (say single-field slow-roll inflation) gracefully exit or not? Is it like showing that inflation is ending at some value of inflaton?

@PeterDonis Thanks a lot for your kind reply.

Hi @PeterDonis, Thanks a lot for your kind reply. The first answer is clear to me. About the second question - I am sorry for my mistake. But, I still have the confusion. I know Riemann tensor as ##R^{\eta }_{\; \mu \nu \alpha} = \frac{\partial \Gamma^{\eta}_{\mu \alpha}}{\partial x^{\nu}}+...

@PeterDonis Thanks a lot. I missed the latex option. I am sorry.

From the section[5.1] of 'Homogeneity and Isotropy' from General Relativity by Robert M. Wald (pages 91-92, edition 1984) whatever I have understood is that - ##\Sigma_t## is a spacelike hypersurface for some fixed time ##t##. The hypersurface is homogeneous. The metric of whole space is ##g##...