P-wave polarization of the ϱ-meson and the dilepton spectrum in dense matter

Abstract

We study the p-wave polarization operator of the ρ-meson due to ρN interactions via the N * (1720) and ∆(1905) resonances and compute the corresponding production rate for e + e − -pairs at finite temperature and baryon density. At high baryon density we find a significant shift of the spectrum to lower invariant masses.

Momentum dependence of the pion cloud for ϱ-mesons in nuclear matter

“…(6.7).) Again, in a realistic calculation resonance contributions of the type ρ → Bh have to be taken into account [12,15].…”

“…A second important effect is expected from baryonic resonance formation through direct interactions of the ρ meson with nucleons. This was considered first by Friman and Pirner [15] and investigated extensively by Peters et al [16].…”

The impact of chirally odd condensates on the rho meson

“…Such a broadening can be obtained in hadronic many-body approaches, e.g., [10][11][12][13][14], which at first sight are not related directly to chiral restoration in the above spirit. Pion dynamics and resonance formation, both fixed to vacuum data, provide the important input for such many-body calculations.…”

“…Additional non-scalar condensates come into play, in particular for in-medium situations. In (10,11), only the twisttwo non-scalar condensates [27] are displayed,…”

ρ→ππ decay in nuclear medium

“…It is commonly accepted that hadrons are significantly modified by nuclear matter. The arguments range from simple scaling of masses [1,2], through numerous hadronic model calculations [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17], QCD sum-rule techniques [18,19,20], approaches motivated by the chiral symmetry [21,22,23,24,25,26,27,28], to modelindependent predictions based on low-density expansion and dispersion relations [29,30,31,32]. In these calculations masses of hadrons, or widths, or both, are significantly changed by the presence of the medium (for a recent review see [33,34,35]).…”