Why Is There a Negative Sign in the Differential Cross Section?

In summary, a negative Feynman amplitude is a mathematical quantity used in quantum field theory to calculate the probability of a particular interaction between particles. It can be calculated using the Feynman diagram and can have physical significance in predicting the behavior of particles at the subatomic level. A negative amplitude implies a decrease in the number of particles and is used in experiments to make predictions and test theories.
  • #1
thoms2543
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I have a process that a scalar and a photon at the final state. When we take the complex conjugate and sum over photon final polarization state...it give negative sign in the differential cross section...what does this mean? the trace didn't give negative value.


[tex]M[/tex]=[tex]M^{\mu}[/tex][tex]\cdot[/tex][tex]\epsilon_{\nu}[/tex]

[tex]\sum[/tex][tex]\left|M\right|^2[/tex]=-[tex]M^{\mu}[/tex][tex]M_{\mu}[/tex]
 
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  • #2
a negative sign in the cross section means you made a mistake!
 

Related to Why Is There a Negative Sign in the Differential Cross Section?

1. What is a negative Feynman amplitude?

A negative Feynman amplitude is a mathematical quantity used in quantum field theory to calculate the probability of a particular interaction between particles. It represents the likelihood of a particle going from one state to another, and can be either positive or negative depending on the specific interaction.

2. How is a negative Feynman amplitude calculated?

A negative Feynman amplitude is calculated using the Feynman diagram, which is a visual representation of the interaction between particles. The amplitude is derived from the mathematical equations that describe the behavior of the particles involved in the interaction.

3. Can a negative Feynman amplitude have physical significance?

Yes, a negative Feynman amplitude can have physical significance. It is a crucial component of quantum field theory and is used to make predictions about the behavior of particles at the subatomic level. However, the physical interpretation of a negative amplitude may differ depending on the specific context.

4. What does a negative Feynman amplitude imply?

A negative Feynman amplitude implies that the interaction between particles is more likely to result in a decrease in the number of particles rather than an increase. This can be interpreted as either a loss of energy or a decay process.

5. How are negative Feynman amplitudes used in experiments?

Negative Feynman amplitudes are used to make predictions about the outcomes of experiments involving subatomic particles. By calculating the amplitudes for various interactions, scientists can determine the likelihood of a particular outcome and compare it to the actual results of the experiment to test the validity of their theories.

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