Special Relativity and the Particle-Antiparticle Problem

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SUMMARY

The discussion centers on the particle-antiparticle problem within the framework of Quantum Mechanics and Special Relativity, specifically addressing the behavior of particles in space-like intervals. Key references include Michael Peskin's "An Introduction to Quantum Field Theory" and Steven Weinberg's "Gravitation and Cosmology." The analysis reveals that in Class A frames, where the condition c < k < c²/v holds, particles and antiparticles can travel in the same direction while their probability amplitudes cancel each other out. The discussion emphasizes the importance of maintaining temporal order in these frames and the need for clear mathematical representation using LaTeX for better comprehension.

PREREQUISITES
  • Understanding of Quantum Mechanics principles, particularly particle-antiparticle interactions.
  • Familiarity with Special Relativity concepts, including space-like intervals and Lorentz transformations.
  • Knowledge of the Klein-Gordon field as presented in quantum field theory.
  • Ability to interpret mathematical expressions in LaTeX format for clarity in complex discussions.
NEXT STEPS
  • Study the Klein-Gordon equation and its implications for particle physics.
  • Explore the concept of space-like intervals in detail, particularly in the context of Lorentz transformations.
  • Investigate the role of probability amplitudes in quantum mechanics and their cancellation in particle-antiparticle scenarios.
  • Learn how to effectively use LaTeX for rendering mathematical equations in online discussions.
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Physicists, students of quantum mechanics, and anyone interested in the intricacies of particle physics and the implications of Special Relativity on particle-antiparticle interactions.

Anamitra
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In Quantum Mechanics we have the possibility of particles shooting across a space-like interval (the probability amplitudes of the particles get canceled by those of the antiparticles shooting across in the reverse direction as seen by an observer in the boosted frame). I have found this fact in
1) Michael Peskin's "An Introduction to Quantum Field Theory" Chapter 2[The Klein Gordon Field],Subsection 2.1,The Necessity of the Field View Point.
2)Steven Weinberg's "Gravitation and Cosmology", Chapter 2[Special Relativity],Section 13,Temporal Order and Antiparticles

My Problem:
We consider such an interval in the unprimed frame given by the space-time coordinates (t1, x1) and (t2,x2) where,

(x2-x1)/(t2-t1)=k>c

We assume t2>t1

In the primed frame,

x1’=gamma (x1-vt1)

t1’=gamma(t1-(v/c^2)x1)

x2’=gamma (x2-vt2)

t2’=gamma(t2-(v/c^2)x2)



t2’-t1’=gamma[(t2-t1)-(v/c^2)(x2-x1)]

=gamma(t2-t1)(1-k(v/c^2))

Temporal reversal takes place in the primed frame provided,

k>c^2/v

We consider an unprimed frame which belong to the category

c<k<c^2/v

Such frames pertain to space-like intervals in the unprimed frame whose temporal coordinates do not get reversed in the primed frames. Let us categorize such frames(in the primed systems) as ”Class A”

My queries: How do they explain the particle-antiparticle problem in relation to the Class A frames? Do the particles and the antiparticles travel in the same direction for these cases and still their amplitudes cancel?Do these frames really cause any confusion?

It is important to note that space-like separations in the unprimed frame do remain space-like separations in the primed frame in relation to the “CLASS A “ category [despite maintenance of temporal order] This may be easily verified by simple calculations.
 
Last edited:
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I am not getting any reply even after a long time.I am feeling more and more confused!
 
It would help if you would mark up your math in LaTeX. Personally, I'm disinclined to spend a lot of time deciphering a long, mathematical post that isn't rendered in my browser as equations.
 

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