| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2000: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
We performed numerical studies of the Kugo-Ojima color confinement criterion, gluon propagator, ghost propagator, Zwanziger's horizon function and the running coupling α_s, in terms of non-perturbative dynamics of QCD in infrared region. In view of importance of Kugo-Ojima confinement criterion, we changed the original research plan and considered its measurement of the confimenment parameter as our main theme, and obtained some other important observations as follows.
1. The Kugo-Ojima color confinement criterion u=-δ^b_a is not perfectly satisfied but it is about u=-0.7δ^b_a.
2. The absolute value of the gluon propagator depends on the definition of the gauge field i.e.U-linear gives a smaller value than logU by about 20%. This result agrees with the idea that up to second order in lattice spacing a, the difference is due to the renormalization effect.
3. If the divergence of the ghost propagator in the infrared region is parameterised as q^<-2(1+κ)>, we observe κ【similar or equal】0.2 i
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n the case of 16^4 lattice. It has the increasing tendency as the lattice size increases. While the log -U and U=linear definition of the gluon field leads to a difference in the overall numerical factor in the gluon propagator, it leads to a significant difference in κ, i.e.the power behavior in the ghost propagator, by about a factor of 3.
4. The QCD running coupling α_s can be in principle obtained from the three point function of the gluon fields and the two point function i.e.gluon propagator. In the region of momentum larger than 2GeV/c, the result is consistent with that of Dyson-Schwinger equation, while in the infrared region, statistical cancellation is observed. It depends on whether the gluon propagator remains finite or vanishes in the zero momentum.
5. It is possible to obtain the QCD running coupling α_s from the three point function of ghost, anti-ghost and gluon and the fluctuation is smaller than that obtained from the three gluons. In the region of momentum larger than 2GeV/c, the result is consistent with that of Dyson-Schwinger equation.
6. The Zwanziger's horizon function is negative and the result is consistent with the theory. Less
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