Free-field Dirac Hamiltonian

In summary, the problem involves finding the value of a specific operator, H, in the context of the free-field Dirac Hamiltonian. The solution involves calculating the operator pieces, <-,p',v';+,q',r'|\widehat{c}+s(k)\widehat{c}s(k)|-,p,v;+q,r> and <-,p',v';+q',r'|\widehat{d}+s(k)\widehat{d}s(k)|-,p,v;+q,r>, which are incorrectly calculated in the attempt at a solution. After finding a solution to a similar problem, the errors in the calculation are identified.
  • #1
jonbones
4
0

Homework Statement



This is a simple problem I thought of and I'm get a nonsensical answer.
I'm not sure where I'm going wrong in the calculation.

Find the value of <-,p',v';+,q',r'|H|-,p,v;+,q,r>
where H is the free-field Dirac Hamiltonian

H = [itex]\int[/itex](d3k/(2\pi)3)[itex]\sum[/itex]s([itex]\widehat{c}[/itex]+s(k)[itex]\widehat{c}[/itex]s(k)+([itex]\widehat{d}[/itex]+s(k)[itex]\widehat{d}[/itex]s(k))

Homework Equations



<p|q> = 2Ep(2\pi)3[itex]\delta[/itex](3)(p-q)

|+,q,r> = (2Eq)1/2[itex]\widehat{d}[/itex]+r(q)|0>

|-,p,v> = (2Ep)1/2[itex]\widehat{c}[/itex]+v(p)|0>

The Attempt at a Solution



<-,p',v';+,q',r'|H|-,p,v;+,q,r> = <-,p',v';+,q',r'|Hc|-,p,v;+q,r>+<-,p',v';+q',r'|Hd|-,p,v;+,q,r>

<-,p',v';+q',r'|Hc|-,p,v;+,q,r> = [itex]\int[/itex](d3k/{(2\pi)3)[itex]\sum[/itex]s<-,p',v';+,q',r'|[itex]\widehat{c}[/itex]+s(k)[itex]\widehat{c}[/itex]s(k)|-,p,v;+q,r>
= [itex]\int[/itex](d3k/{(2\pi)3)[itex]\sum[/itex]s<-,p',v'|[itex]\widehat{c}[/itex]+s(k)[itex]\widehat{c}[/itex]s(k)|-,p,v><+,q',r'|+q,r>
= 1/(2\pi)3(2Ev)-1<-,p',v'|-,p,v><+q',r'|+q,r>
= (2\pi)32Eq[itex]\delta[/itex](3)(v-v')[itex]\delta[/itex](3)(q-q')

Similarly, <-,p',v';+q',r'|Hd|-,p,v;+,q,r> = (2\pi)32Ev[itex]\delta[/itex](3)(v-v')[itex]\delta[/itex](3)(q-q')

I know these are wrong since <-,p',v';+q',r'|Hc|-,p,v;+,q,r> [itex]\propto[/itex]Ep and <-,p',v';+q',r'|Hd|-,p,v;+,q,r> [itex]\propto[/itex]Eq.

I'm pretty sure I'm calculating the operator pieces like <-,p',v';+,q',r'|[itex]\widehat{c}[/itex]+s(k)[itex]\widehat{c}[/itex]s(k)|-,p,v;+q,r> incorrectly but I'm not sure where I'm going wrong.

-- Jonathan
 
Physics news on Phys.org
  • #2
Nevermind, I found a solution to a similar problem and now I know what I did wrong.
 

1. What is the Free-field Dirac Hamiltonian?

The Free-field Dirac Hamiltonian is a mathematical operator used in quantum field theory to describe the dynamics of a free fermion field (such as an electron) in space and time. It is based on the Dirac equation, which is a relativistic wave equation describing the behavior of spin-1/2 particles.

2. How is the Free-field Dirac Hamiltonian derived?

The Free-field Dirac Hamiltonian is derived from the Dirac Lagrangian, which describes the dynamics of a free fermion field in terms of its energy and momentum. This Lagrangian is then quantized using the canonical formalism, resulting in the Free-field Dirac Hamiltonian operator.

3. What is the significance of the Free-field Dirac Hamiltonian?

The Free-field Dirac Hamiltonian is significant because it allows for the calculation of physical observables, such as energy and momentum, in a quantum field theory. It also provides a framework for understanding the behavior of fermions, which are particles with half-integer spin.

4. How does the Free-field Dirac Hamiltonian differ from the Dirac Hamiltonian?

The Free-field Dirac Hamiltonian differs from the Dirac Hamiltonian in that it describes a free fermion field, whereas the Dirac Hamiltonian includes interactions with other fields or particles. The Free-field Dirac Hamiltonian is also simpler and easier to solve, making it a useful tool in theoretical physics.

5. What are some applications of the Free-field Dirac Hamiltonian?

The Free-field Dirac Hamiltonian has many applications in quantum field theory, including in the study of particle physics, condensed matter physics, and quantum information theory. It is also used in the development of quantum algorithms and in the calculation of physical quantities in relativistic systems.

Similar threads

  • Advanced Physics Homework Help
Replies
1
Views
1K
  • Advanced Physics Homework Help
Replies
1
Views
681
Replies
27
Views
2K
  • Advanced Physics Homework Help
Replies
8
Views
1K
  • Advanced Physics Homework Help
Replies
19
Views
815
  • Advanced Physics Homework Help
Replies
1
Views
939
  • Advanced Physics Homework Help
Replies
10
Views
567
Replies
1
Views
961
  • Advanced Physics Homework Help
Replies
5
Views
1K
  • Advanced Physics Homework Help
Replies
1
Views
769
Back
Top