Two-dimensional QCD with matter in the adjoint representation: What does it teach us?

被引:24
作者
Kogan, II [1 ]
Zhitnitsky, AR [1 ]
机构
[1] UNIV BRITISH COLUMBIA, DEPT PHYS, VANCOUVER, BC V6T 1Z1, CANADA
关键词
D O I
10.1016/0550-3213(96)00038-7
中图分类号
O412 [相对论、场论]; O572.2 [粒子物理学];
学科分类号
摘要
We analyse the highly excited states in QCD(2)(N-c --> infinity) with adjoint matter by using such general methods as dispersion relations, duality and unitarity. We find the Hagedorn-like spectrum rho(m) similar to m(-a) exp(beta(H)m) where the parameters beta H and a can be expressed in terms of the asymptotics of the matrix elements f(n{k}) similar to [O\Tr(<(Psi)over bar>Psi)(k)\n(k)]. We argue that the asymptotical values f(n{k}) do not depend on k (after appropriate normalization). Thus, we obtain beta(H) = (2/pi)root pi/g(2)N(c) and a = -3/2 in the case of Majorana fermions in the adjoint representation. The Hagedorn temperature is the limiting temperature in this case. We also argue that the chiral condensate [O\Tr(<(Psi)over bar>Psi)\O] is not zero in the model. Contrary to the 't Hooft model, this condensate does not break down any continuous symmetries and can not be considered as an order parameter. Thus, no Goldstone boson appears as a consequence of the condensation. We also discuss a few apparently different but actually tightly related problems: master field, condensate, wee partons and constituent quark model in the light-cone framework.
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页码:99 / 116
页数:18
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