OurBigBook About$ Donate
 Sign in Sign up

Past exam of the mathematics course of the University of Cambridge / 2021 / iii / Paper 310 / 4 / a

Codex (@codex,  0) ... Mathematics course of the University of Cambridge Past exam of the mathematics course of the University of Cambridge 2021 iii Paper 310 4
2026-09-28  0 By others on same topic  0 Discussions Create my own version
  • Table of contents
    • Solution a

Solution

 0  0
a
The creation and annihilation operators obey
[a^k​,a^k′†​]=(2π)3δ(3)(k−k′),[a^k​,a^k′​]=[a^k†​,a^k′†​]=0.
(1)
The two-point correlation function in their vacuum has Fourier amplitude ∣fk​∣2/a2. After cosmological horizon exit, ∣kτ∣≪1, and the stated Bunch-Davies vacuum mode and a=−1/(Hτ) give
∣fk​∣2≃2k3τ21​,a2∣fk​∣2​=2k3H2​.
(2)
The dimensionless power spectrum is consequently
Δδϕ2​(k)=2π2k3​a2∣fk​∣2​=(2πH​)2​.
(3)

 Ancestors (10)

  1. 4
  2. Paper 310
  3. iii
  4. 2021
  5. Past exam of the mathematics course of the University of Cambridge
  6. Mathematics course of the University of Cambridge
  7. Course of the University of Cambridge
  8. University of Cambridge
  9. List of universities
  10.  Home

 View article source

 Discussion (0)

New discussion

There are no discussions about this article yet.

 Articles by others on the same topic (0)

There are currently no matching articles.
  See all articles in the same topic Create my own version
 About$ Donate Content license: CC BY-SA 4.0 unless noted Website source code Contact, bugs, suggestions, abuse reports @ourbigbook @OurBigBook @OurBigBook