## Abstract

A new formulation of QCD sum rules at finite temperature (T) is developed. Because of the factorization in the operator product expansion, all the soft dynamics including the effect of finite T in the hadronic phase is taken into account in the thermal average of local operators 〈¢O〉_{T}. Unlike for the T = 0 case, 〈¢O〉_{T} has non-vanishing values for the Lorentz non-scalar operators such as vγ_{μ}D_{v}q. On the basis of the observation that the finite-temperature medium can be well approximated by a dilute (non-interacting) pion gas at low T, one can make a sensible estimate of the T-dependence of various condensates, where the current algebra and the experimental information of the pion structure functions turn out to be a useful guide. We applied this method to the light vector mesons (ρ{variant}, ω and A_{1}) and found that the change of the four-quark condensate at T ≠ 0 is crucial to the change of meson properties. The lepton pair production rate from the hot hadronic medium near the ρ{variant}-resonance is calculated using the result of the sum rules. This has direct relevance to the detection of the lepton pairs in future projects of the ultra-relativistic heavy-ion collisions such as RHIC and LHC.

Original language | English |
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Pages (from-to) | 221-264 |

Number of pages | 44 |

Journal | Nuclear Physics, Section B |

Volume | 394 |

Issue number | 1 |

DOIs | |

Publication status | Published - 1993 Apr 5 |

### Bibliographical note

Funding Information:We would like to thank M. Asakawa, M.K. Banerjee, G.E. Brown, T.D. Cohen, B.L. loffe, C.M. Ko, 0. Morimatsu, J. Qiu, E.V. Shuryak, K. Tanaka and S.J. Wallace for useful discussions. This work was supported by the U.S. Department of Energy (D.O.E.) under grant #DE-FGO6-90ER40561, #DE-FGO5-87ER-40322, and the NON-DIRECTED research fund of Korea Science foundation Ministry of Education, and partially by KOSEF through CTP in Seoul National University.

## All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics