6. wilsonian matching
DESCRIPTION
6. Wilsonian Matching. 6.1 Basic Concept. ◎ Generating functional in QCD. J : external source fields. ◎ Generating functional in EFT. F : parameters of EFT. ☆ Wilsonian matching. bare theory. high energy. QCD. quarks and gluons. L. matching. HLS. r and p. Bare theory. - PowerPoint PPT PresentationTRANSCRIPT
◎ Generating functional in QCD
◎ Generating functional in EFT
☆ Wilsonian matching
J : external source fields
F : parameters of EFT
bare theory
QCD quarks and gluons
Bare theory
HLS and
bare parameters
Quantum effects
Quantum theory
physical quantities
matching
high energy
low energy
☆ Axialvector current correlator
in space-like region
◎ low energy limit ・・・ π dominance
◎ high energy region ・・・ Operator Product Expansion (OPE)
・・・ renormalization scale of QCD
F (0)π2
μ 2
Λ ~ 1 GeV
◎ Around Q2 ~ Λ2 ~ (1 GeV)2
・ Integrating out quarks and gluons ・・・ not well-defined degrees of freedom in the low energy region
・ bare HLS Lagrangian including O(p ) terms4
F (0)π2
F (Λ)π2
Λ
◎ Λ > μ ・・・ inclusion of quantum corrections from π and ρ
# Λ > μ > m ・・・ through RGEρ
F (0)π2
Λmρ
OPEHLS
μ 2
F (μ)π2
# m > μ ・・・ through the RGE in ChPTρ
mρ Λμ 2
OPE
F (0)π2
F (μ)π2
HLSChPT
[F (μ )]π(π ) 2[F (μ )]π(π ) 2
effect of finite renormalization
☆Axialvector and Vector Current Correlators
◎ HLS
◎ QCD (OPE)
Matching
☆ Wilsonian Matching Conditions
◎
◎
◎
☆ Matching Scale Λ • large enough for validity of OPE• small enough for validity of HLS
Λ = 1.0 ~ 1.2 GeV
☆ Bare parameters
☆ Inputs3 Wilsonian matching conditions
・ Inputs for OPE
☆ Values of bare parameters
☆ Values of bare parameters (leading order)
☆ Values of bare parameters (next order)
☆ Parameters at m scaleρ
bare parameters → (RGE) → parameters at mρ
☆ Physical Predictions
4 quantities directly related to experiment
◎ ρ- γ mixing strength
・ tree
・ loop
・ typical prediction
cf :
through RGE
◎ Gasser-Leutwyler’s parameter L10
・ typical prediction
cf :
◎ ρππ coupling
・ bare Lagrangian
loop effects through RGE
・ effective interaction
・ typical prediction
cf :
◎ Gasser-Leutwyler’s parameter L9
・ typical prediction for
cf :
◎ parameter a(0) ・・・ characterize Vector dominance
・ typical prediction
・ bare Lagrangian
loop effects through RGE
・ effective interaction
・・・ VD is well satisfied
◎ running of a
◎ Summary of Predictions
☆ Why π - π mass difference ? + 0
◎ ⇔ vacuum structure
M.E. Peskin 80’, J. Preskil 80’
⇒ stability of U(1)em symmtric vacuum
⇒ instability : U(1)em is broken
◎ ⇔ mass of little Higgs
M.H. M.Tanabashi and K.Yamawaki, Phys. Lett. B 568 103 (2003)
6.5 π+ - π0 Mass Difference and Wilsonian Matching
☆ How to calculate ?
◎ A formula from Dashen’s theorem
bare parameter improve by RGE
☆ Determination of the bare parameter
☆ Prediction
Quantum correction through RGE
> 0
in good agreement