Dirac Field quantization and anti-commutator relation

In summary, the conversation discusses the calculation of the set of equations 5.4 in David Tong's notes, which leads to the expression Σ_s Σ_r [b_p^s u^s(p)e^{ipx} b_q^r†u^r†(q)e^{-iqy}+ b_q^r †u^r†(q)e^{-iqy} b_p^s u^s(p)e^{ipx}]. The question is why this expression cannot be written as Σ_sΣ_r[ \{b_p^s, b_q^r †\} u^s(p)u^r†(q)e^{i.(p.x-q.y)}],
  • #1
sakh1012
1
0
Can anyone explain while calculating $$\left \{ \Psi, \Psi^\dagger \right \} $$, set of equation 5.4 in david tong notes lead us to
$$Σ_s Σ_r [b_p^s u^s(p)e^{ipx} b_q^r†u^r†(q)e^{-iqy}+ b_q^r †u^r†(q)e^{-iqy} b_p^s u^s(p)e^{ipx}].$$

My question is how the above mentioned terms can be written as
$$Σ_sΣ_r[ \{b_p^s, b_q^r †\} u^s(p)u^r†(q)e^{i.(p.x-q.y)}]$$.And why not
$$Σ_sΣ_r[ \{b_p^s, b_q^r †\} u^r†(q)u^s(p)e^{i.(p.x-q.y)}]$$
As per my knowledge $$u^s(p)u^r†(q)!= u^r†(q) u^s(p)$$
please see equation 5.6 in david tong notes. $s$ and $r$ are spinor index and summed over 1-2.
http://www.damtp.cam.ac.uk/user/tong/qft/five.pdf
 
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  • #2
The u's are spinors (usually written as 4d columns). So for sure the last equation doesn't make sense, because
##u^s(p) u^{r \dagger}(q)## is ##4 \times 4##-matrix while ##u^{r \dagger}(q) u^s(p)## is a complex number.
 

1. What is Dirac Field quantization?

Dirac Field quantization is a mathematical framework used to describe the behavior of quantum fields, which are fundamental entities that describe the behavior of particles at the subatomic level. This framework is based on the principles of quantum mechanics and is used to calculate the probability of different outcomes of a quantum system.

2. What is the anti-commutator relation in Dirac Field quantization?

The anti-commutator relation in Dirac Field quantization is a mathematical relationship between two operators that represent different physical quantities. It is used to describe the behavior of fermions, which are particles that follow the rules of quantum mechanics and have half-integer spin. The anti-commutator relation is an important tool for calculating the properties of fermions in quantum systems.

3. How is the Dirac Field quantized?

The Dirac Field is quantized by breaking it down into a series of harmonic oscillators, each of which is associated with a different momentum and spin. This allows for the calculation of the probability of different outcomes of a quantum system, such as the position and momentum of a particle.

4. What is the significance of the anti-commutator relation in quantum field theory?

The anti-commutator relation is significant in quantum field theory because it helps to describe the behavior of fermions, which are particles that follow the rules of quantum mechanics. It is also used to calculate the properties of fermions in quantum systems, such as their spin and momentum.

5. How does the anti-commutator relation differ from the commutator relation?

The anti-commutator relation differs from the commutator relation in that it uses the anti-commutator operator, which is defined as the product of two operators with the order of the operators reversed and a negative sign. This is in contrast to the commutator operator, which is defined as the product of two operators with the order of the operators unchanged and no negative sign.

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