Space-like virtualities of partons

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In summary, the conversation discusses the use of PYTHIA, an event generator, to simulate parton showers in the process e+ e- → γ*/Z0→q \bar{q}→parton showers (PYEEVT). It is noted that some produced partons have imaginary masses, indicating space-like virtualities. This is unusual as space-like partons typically come from initial state radiation, which is not present in this process. The individual questions why this is happening and what it means, but notes that PYTHIA has been extensively tested and corrected over many years. An attached event list shows that all particles from 4-43 are virtual, but particles after 44 appear to have real masses.
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Kyong
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I used PYTHIA (an event generator) to have parton showers from the process e+ e- → γ*/Z0→q \bar{q}→parton showers (PYEEVT).
I realized that some partons (gluons or quarks) produced in this process have imaginary masses (Q2=E2-px2-py2-pz2<0), i.e. space-like virtualities.
As I know, space-like partons usually come from initail state radiation. However, in case of the above process, there is no initial state radiation.
I don't believe that PYTHIA was wrong because PYTHIA has been corrected and polished much by many people for about thirty years(?).
Can anybody explain me why the space-like virtualities happened and what they mean?
I attached a text file for an event list.
 

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All particles 4-43 are virtual. Why do you expect a positive (real) mass there?
All particles after 44 look real.
 

FAQ: Space-like virtualities of partons

What are space-like virtualities of partons?

Space-like virtualities of partons refer to the virtual particles that exist in the vacuum of space, specifically in the region between two colliding particles. These virtual particles are considered "off-shell," meaning that they do not follow the usual mass-energy relationship, and they can only exist for a very short period of time before disappearing.

How are space-like virtualities of partons studied?

Space-like virtualities of partons are studied using high-energy particle colliders, such as the Large Hadron Collider (LHC) at CERN. These colliders accelerate particles to nearly the speed of light and collide them, producing a shower of particles, including virtual particles, which can then be studied by detectors.

What is the significance of studying space-like virtualities of partons?

Studying space-like virtualities of partons allows scientists to better understand the fundamental forces and particles that make up the universe. It also helps to test and refine theories, such as the Standard Model, which describes the interactions of particles and the forces between them.

What types of particles can be produced in space-like virtualities?

Space-like virtualities can produce a variety of particles, including quarks, gluons, and photons. These particles play a crucial role in the structure and behavior of matter and are essential to our understanding of the universe.

What practical applications can come from studying space-like virtualities of partons?

Studying space-like virtualities can lead to practical applications in fields such as medicine and technology. For example, understanding the behavior of particles in extreme conditions, such as those found in space-like virtualities, can help in the development of new medical imaging techniques or advanced materials for technology.

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