Thermal masses in particle kinematics - thermal field theory

In summary: Your Name]In summary, the inclusion of thermal masses in the kinematics of particle scattering and Boltzmann equations is justified in thermal field theory due to the constant interactions between particles and the surrounding medium. These thermal masses, which are dependent on the temperature of the medium, affect the energy and momentum conservation laws, leading to modifications in scattering cross sections and decay rates. Further explanations can be found in textbooks on thermal field theory or articles specifically discussing this issue.
  • #1
Clemens
1
0
Hi,

I decided to open a knew thread since I was not sure whether my problem is close enough to the existing thread "FTFT for computing particle scattering".
When dealing with Thermal Field Theory in the early universe, some people (eg. Giudice et al. hep-ph/03010123, Weldon PhysRevD26,10(1982)) include thermal masses in the particle kinematics and the Boltzmann equations. Since the leading corrections are proportional to the temperature, the effects can be huge.
I believe this approach is justified, but I have not found a good explanation for that. The literature I know explains the modification of propagators by resumming self-energies which leads to a modification of the denominator. So far I understand the issue. However, it is not clear to me why one can use thermal masses in the kinematics of scattering cross sections, decay rates or Boltzmann equations.
Does anyone know literature which explains this issue in a good way?

Thank you,

Clemens Kießig
 
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  • #2


Hello Clemens Kießig,

Thank you for bringing up this interesting topic. I can understand your confusion about the inclusion of thermal masses in the kinematics of particle scattering and Boltzmann equations. Let me try to explain this in a simple way.

First of all, let's discuss what thermal masses are. In thermal field theory, the particles are assumed to be in thermal equilibrium with the surrounding medium. This means that they are constantly interacting with the particles in the medium, exchanging energy and momentum. This leads to a modification of the particles' masses, known as thermal masses. These thermal masses are dependent on the temperature of the medium and can be significantly different from the vacuum masses of the particles.

Now, coming to your question, why do we use thermal masses in the kinematics of particle scattering and Boltzmann equations? The answer lies in the fact that in a thermal medium, the particles are constantly interacting and exchanging energy and momentum. This means that the kinematics of the particles are affected by the medium, and their thermal masses need to be taken into account. For example, in particle scattering, the thermal masses affect the energy and momentum conservation laws, leading to a modification of the scattering cross section. Similarly, in Boltzmann equations, the thermal masses affect the decay rates of particles, which in turn affects the number densities of particles in the medium.

There are several ways to understand this concept, and different literature may provide different explanations. I would suggest looking into textbooks on thermal field theory or articles specifically discussing the inclusion of thermal masses in particle kinematics and Boltzmann equations. Some useful references could be "Thermal Field Theory" by Michael Le Bellac and "Introduction to Thermal Field Theory" by Stefano Bellucci and Marco Zeni.

I hope this helps clarify your doubts. Let me know if you have any further questions.


 
  • #3


Hello Clemens,

Thank you for bringing up this interesting topic. Thermal masses in particle kinematics are an important concept in the field of Thermal Field Theory. This approach takes into account the effects of temperature on the particles and their interactions, which can have significant implications in the early universe or in high energy experiments.

To understand why thermal masses are used in the kinematics of scattering cross sections, decay rates, and Boltzmann equations, we need to look at the fundamental principles of Thermal Field Theory. In this theory, the particles are described as excitations of a thermal bath, which is in a state of thermal equilibrium at a certain temperature. This means that the particles are constantly interacting with the surrounding medium, and their properties, such as mass, can be affected by this interaction.

The inclusion of thermal masses in the kinematics of scattering cross sections and decay rates can be understood by considering the effect of the thermal bath on the particles. As the particles move through the thermal bath, they interact with the surrounding particles and acquire an effective mass, which is different from their vacuum mass. This effective mass is temperature-dependent and can be calculated using the resummation of self-energies, as you mentioned. By taking into account this temperature-dependent mass in the kinematics, we can accurately describe the behavior of the particles in a thermal environment.

Similarly, in the Boltzmann equation, the thermal mass is used to account for the effects of temperature on the particles' interactions and their number density. This is important in understanding the dynamics of the system and predicting the evolution of the thermal bath.

In summary, the use of thermal masses in particle kinematics is justified by the principles of Thermal Field Theory, where the particles are considered as excitations of a thermal bath. These thermal masses take into account the effects of temperature on the particles and their interactions, allowing for a more accurate description of their behavior in a thermal environment. I hope this helps clarify the issue for you.

Best regards,
 

1. What is the significance of thermal masses in particle kinematics?

Thermal masses play a crucial role in determining the behavior of particles in a hot or dense environment. They represent the effective mass of a particle in a thermal system, taking into account the interactions with other particles and the surrounding thermal field.

2. How are thermal masses calculated in particle kinematics?

Thermal masses are typically calculated using thermal field theory, which is an extension of quantum field theory that takes into account the effects of temperature on the behavior of particles. This involves using statistical mechanics and perturbation theory to calculate the thermal correction to the masses of particles.

3. Can thermal masses change the properties of particles?

Yes, thermal masses can significantly affect the properties of particles in a thermal system. They can change the energy levels, decay rates, and scattering cross-sections of particles, leading to different experimental signatures compared to the same particles in a vacuum.

4. How do thermal masses differ from vacuum masses?

Thermal masses are generally larger than vacuum masses due to the interactions with the surrounding thermal field. This is because the thermal field can provide additional energy to particles, leading to an increase in their effective mass.

5. What are some applications of thermal masses in particle kinematics?

Thermal masses are crucial for understanding the behavior of particles in high-energy collisions, such as those that occur in particle accelerators. They also play a significant role in cosmology, where the early universe was a hot and dense thermal system, affecting the evolution and properties of particles.

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