It is actually called "decay width".maximdogger said:thanks ..I will look up mass width.
The mass of an "unstable particle" (or more accurately a resonance) is a well-defined number. It's given by the complex pole of its Green's function in (four-)momentum space, i.e., the real part of this pole is the mass and the imaginary part is its decay width, i.e., the inverse mean lifetime.malawi_glenn said:No idea what "when viewed" means.
There is however a concept of mass width in QFT for unstable particles.
Yup.vanhees71 said:The mass of an "unstable particle" (or more accurately a resonance) is a well-defined number. It's given by the complex pole of its Green's function in (four-)momentum space, i.e., the real part of this pole is the mass and the imaginary part is its decay width, i.e., the inverse mean lifetime.
I used that paper when I was starting my phd heheDemystifier said:No, but the mass of "unparticle" fluctuates.
https://arxiv.org/abs/0801.4471
Mass is a measure of the amount of matter in an object. It is typically measured in units of kilograms (kg) or grams (g).
According to the theory of relativity, mass is a constant property of a particle and does not change over time. However, in certain situations, such as at high speeds or in extreme gravitational fields, the mass of a particle may appear to change due to relativistic effects.
Einstein's famous equation, E=mc^2, states that mass and energy are equivalent and can be converted into each other. This means that a particle's mass can be converted into energy and vice versa.
In particle physics, mass is determined by measuring the particle's momentum and energy. This can be done using techniques such as particle accelerators and detectors.
No, a particle's mass is an intrinsic property and is not affected by external factors. However, the mass of a particle may appear to change when interacting with other particles or fields, but this is not a true fluctuation in mass.