Study of the standard model for elementary particles at the finite temperature
Project/Area Number  09640342 
Research Category 
GrantinAid for Scientific Research (C)

Allocation Type  Singleyear Grants 
Section  一般 
Research Field 
素粒子・核・宇宙線

Research Institution  Yokohama National University 
Principal Investigator 
SASAKI Ken Faculty of Engineering, Professor, 工学部, 教授 (00114976)

Project Period (FY) 
1997 – 1998

Project Status 
Completed(Fiscal Year 1998)

Budget Amount *help 
¥1,400,000 (Direct Cost : ¥1,400,000)
Fiscal Year 1998 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1997 : ¥800,000 (Direct Cost : ¥800,000)

Keywords  Quark and gluon / Quantum Chromodynamics / Finite Temperature / Thermal beta function / Gaugeinvariant / Selfenergy / Structure function / Spin 
Research Abstract 
(1) The pinch technique (PT) is applied to obtain the gaugeindependent resummed gluon selfenergy in a hot YangMills gas. The effective gluon selfenergy, which is obtained as the sum of the resummed gluon selfenergy and the resummed pinch contributions, is not only gaugeindependent but also satisfies the transversality relation. Using this gaugeindependent effective gluon selfenergy, we calculate the damping rate for transverse gluons in the leading order and show that the result coincides with the one obtained by Braaten and Pisarski. (2) It is shown in the framework of the operator product expansion and the renormalization group method that the twist3 part of flavor nonsinglet spin structure function g_2(x, Q^2) of nucleon obeys a simple DokshitzerGribovLipatovAltarelliParisi (DGLAP) equation in the large N_C limit even in the case of massive quarks (N_C is the number of colours). (3) The virtual photon structure function g_1^<gamma> (x, Q^2, P^2), which can be obtained in polarized e^+ +e^ & collidingbeam experiments, is investigated for LAMBDA^2>>P^2>>Q^2, where Q^2 (P^2) is the mass squared of the probe (target) photon. The analysis is made to nexttoleading order in QOD, in the framework of the QCD improved parton model with the DGLAP evolution equations. The nonleading corrections significantly modify the leading log result, in particular, at large x as well as at small x.

Report
(3results)
Research Products
(17results)