Challenges in Modern Physics

1
Challenges in Modern Physics

• What are the building blocks of matter?

• What happens if one tries to separate two quarks?

• The properties of strong force at large distance
  represents one of the biggest intellectual
  challenges in physics.

2
What is symmetry?
Symmetry is an invariance of a physical system to
a set of changes .
Symmetry and symmetry breaking are fundamental in
the laws of physics
3
Spontaneous Chiral Symmetry Breaking Gives Rise
to p0

• In
  the quark massless limit

• Corrections to theory
• Non-zero quark masses generates meson masses
• Quark mass differences causes mixing among the
  mesons
• Since p0 is the lightest quark antiquark system
  in nature, the correction is small

4
Axial Anomaly Determines p0 Lifetime

• Features of anomaly
• Unique property of the quantum theory.
• Calculable exactly to all orders in the massless
  quark limit

• Chiral anomaly predicts to leading order
• This prediction is exact for massless
  quarks.
• Recent theoretical calculations of NLO
  corrections
• with an uncertainty of less than 1.

G(p0???) is one of the few quantities in low
energy QCD that can be calculated precisely!
High precision measurement of the p0 lifetime at
percent level will provide a stringent test of a
fundamental prediction of QCD. It ultimately
helps us understand the building blocks of matter
and the force between them.