Question About Complex Scalar Field: Advantages/Disadvantages?

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The discussion centers on the necessity of using complex scalar fields to account for antiparticles in quantum field theory. A complex scalar field is advantageous for modeling charged particles, such as charged pions, while a real scalar field suffices for neutral particles, making them their own antiparticles. The Klein-Gordon equation applies to both types of fields, but the choice impacts particle charge and behavior. The conversation references Schrödinger's work, suggesting that the relationship between particle types and field complexity may not be straightforward. Understanding these distinctions is crucial for accurate particle modeling in quantum mechanics.
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I wanted to ask a quick question about the complex scalar field. My question is that does the scalar field need to be complex in order to include the part for anti-particles or do you regards the scalar field for particles and anti-particles separate. I saw this specifically when you second quantization to quantize the scalar field that satisfies the Klein-Gordon equation. Are there any advantages and disadvantages of making the scalar field complex if it really doesn't apply to what I mentioned above? Thanks in advance for anybody who can clarify this question.
 
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If the field is real, then the particle is its own antiparticle. Note that a real KG field is uncharged.

So, one uses complex KG fields to model spin-0, charged particles, such as the charged pions. (The neutral pion is modeled using a real KG field).
 
Ben Niehoff said:
If the field is real, then the particle is its own antiparticle. Note that a real KG field is uncharged.

Not necessarily, according to Shroedinger (Nature (1952), v.169, p.538). I mentioned this article in several posts.
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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