Browsing by Author "Dominguez, CA"

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    Axial anomaly, vector meson dominance and π0 → γγ at finite temperature
    (2000) Dominguez, CA; Loewe, M
    A thermal Finite Energy QCD Sum Rule is used to determine the temperature behaviour of the omega rho pi strong coupling. This coupling decreases with increasing T and vanishes at the critical temperature, a likely signal for quark deconfinement. This is then used in the Vector Meson Dominance (VMD) expression for the pi(0) --> gamma gamma amplitude, which is also found to vanish at the critical temperature, as expected. This result supports the validity of VMD at T not equal 0. However, if VMD would not hold at finite temperature, then there is no prediction for the pi(0) --> gamma gamma amplitude. (C) 2000 Elsevier Science B.V. All rights reserved.
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    Vector meson dominance and g(rho pi pi) at finite temperature from QCD sum rules
    (1997) Dominguez, CA; Fetea, MS; Loewe, M
    A Finite Energy QCD sum rule at non-zero temperature is used to determine the q(2)- and the T-dependence of the rho pi pi vertex function in the space-like region, A comparison with an independent QCD determination of the electromagnetic pion form factor F-pi at T not equal 0 indicates that Vector Meson Dominance holds to a very good approximation at finite temperature. At the same time, analytical evidence for deconfinement is obtained from the result that g(rho pi pi)(q(2),T) vanishes at the critical temperature T-c, independently of q(2). Also, by extrapolating the rho pi pi form factor to q(2) = 0, it is found that the pion radius increases with increasing T, and it diverges at T = T-c. (C) 1997 Elsevier Science B.V.