QCD sum rules and applications to nuclear physics

Abstract

Applications of QCD sum-rule methods to the physics of nuclei are reviewed, with an emphasis on calculations of baryon self-energies in infinite nuclear matter. The sum-rule approach relates spectral properties of hadrons propagating in the finite-density medium, such as optical potentials for quasinucleons, to matrix elements of QCD composite operators (condensates). The vacuum formalism for QCD sum rules is generalized to finite density, and the strategy and implementation of the approach is discussed. Predictions for baryon self-energies are compared to those suggested by relativistic nuclear physics phenomenology. Sum rules for vector mesons in dense nuclear matter are also considered.

Modification of theBmeson mass in a magnetic field from QCD sum rules

“…Our approach is analogous to the one used to obtain the quark propagator in the QCDSR method in nuclear matter (see, for example, Ref. [42] for a review). The main idea is that one can expand the matrix element h∶q aα ðxÞq bβ ð0Þ∶i ≡ hΩj∶q aα ðxÞq bβ ð0Þ∶jΩi in terms of the usual basis for the Dirac matrices, f1; γ μ ; γ 5 ; γ 5 γ μ ; σ μν g, where as usual σ μν ≡ i½γ μ ; γ ν =2.…”

Relativistic nuclear energy density functional constrained by low-energy QCD

“…To first order in the scalar and baryon densities, these self-energies can be expressed as follows [12,35,36,37,38,39]: …”

“…This remarkable agreement indicates that the initial estimates Eqs. (37) and (38) for the condensate background couplings have perhaps been more realistic than anticipated, considering the uncertainties of lowest-order in-medium QCD sum rules.…”

New Approach to Investigation of Nuclei

“…Later [4] the approach was applied in an investigation of hyperons in nuclear matter. Note that the nucleon self energies in nuclear matter were also calculated in an alternative approach to the SR, based on the dispersion relations in the time component q 0 [5].…”