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SNUTP 97-033,UTHEP-358March.,1997Comment on:“Meson Mass in Nuclear Matter”Tetsuo Hatsuda Institute of Physics,University of Tsukuba,Tsukuba,Ibaraki 305,Japan Su Houng Lee Department of Physics,Yoni University,Seoul,120-749,Korea 21.65.+f,12.40.Vv,14.40.Cs,24.85.+p
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In a recent letter[1],Eletsky and Ioffe estimated the energy shift ofρ-meson with high momentum(q)in nuclei using the Glauber approximation.They also made remarks on the low q vector mesons in medium.In this Comment,we will discuss the cond point and show that(i)mean-field physics for the mass shift of low-q mesons is overlooked in[1],and (ii)the short distant operator product expansion(OPE)is relevant to analyze the low-q mesons in QCD sum rules contrary to the claim in[1].
Mesons in nuclei have considerable multiple scattering when|q|−1≫d(d is the inter-nucleon distance).The relevant quantity here is known to be a polarization function(gener-alized optical potential)Π(ω,q)[2],which is written,up to the Lorentz-Lorenz correction, as
Π(ω,q)=−16π d3p
(∞,finite),and the light-cone(LC)expansion where(Q2,Q2/q·P)→(∞,finite).Both are at best an asymptotic expansion in1/Q2with different composite operators contributing at each order:The SD(LC)expansion is dictated by the dimension(twist)of the operators. Since we are interested in q≃0with P=0,OPE in the deep-euclidian region(−ω2→∞)is obtained from the SD expansion by re-expanding1/Q2and(q·P)2/Q2in terms of 1/ω2,which is a natural generalization of the QCD sum rules in the vacuum[5,8].More importantly,from the analytic properties of Dµν,one can relate the OPE to the spectral density via the well-knownfixed q dispersion relation[7]
Re D(ω2<0,q)= ∞0dx2ρ(x,q)
REFERENCES
[1]V.L.Eletsky and B.L.Ioffe,Phys.Rev.Lett.78,1010(1997).
[2]A.B.Migdal,in Mesons in Nuclei,ed.M.Rho and D.Wilkinson(North-Holland,Ams-
terdam,1979).T.Ericson and W.Wei,Pions and Nuclei,(Oxford Univ.Press,Oxford, 1988).
[3]B.Friman and M.Soyeur,Nucl.Phys.A600,477(1996).
[4]H.C.Jean,J.Piekarewicz and A.G.Williams,Phys.Rev.C49,1981(1994).
[5]T.Hatsuda and Su H.Lee,Phys.Rev.C46,R34(1992).T.Hatsuda,Su H.Lee and H.空调种类
Shiomi,Phys.Rev.C52,3364(1995).
[6]T.Muta,Foundations of Quantum Chromodynamics,(World-Scientific,Singapore,1987).
[7]A.L.Fetter and J.D.Walecka,Quantum Theory of Many-Particle Systems,(McGraw-
Hill,New York,1971).
[8]T.D.Cohen,R.J.Furnstahl,D.K.Griegel and X.M.Jin,Prog.in Part.Nucl.Phys.35,
221(1995),ction3.7.D.K.Griegel,PhD Thesis(Univ.of Maryland)1991.
[9]E.G.Drukarev and E.M.Levin,Prog.Part.Nucl.Phys.27,77(1991).
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