Meson Masses in Nuclear Matter

Abstract

Mass shifts ∆m of particles in nuclear matter relative to their vacuum values are considered. A general formula relating ∆m(E) (E is the particle energy) to the real part of the forward particle-nucleon scattering amplitude Ref (E) is presented and its applicability domain is formulated. The ρ-meson mass shift in nuclear matter is calculated at 2 < ∼ E ρ < ∼ 7 GeV for transversally and longitudinally polarized ρ-mesons with the results: ∆m T ρ ∼ 50 MeV and ∆m L ρ ∼ 10 MeV at normal nuclear density.PACS numbers: 21.65.+f, 12.40.Vv The problem of how the properties of mesons and baryons change in nuclear matter in comparison to their free values has attracted a lot of attention recently. Among these properties the first of interest are mass shifts of particles in nuclear matter. This interest is related to the fact that it was possible to calculate by QCD sum rules and on the lattice almost all masses of low lying mesons and baryons, and a hope appears to extend these calculations to the case of particles is embedded in nuclear medium. On the other hand, the values of particle masses can be measured experimentally -at least some of them -and some data started to appear. In this aspect experiments on heavy ion collisions, in which the dependence of particle masses on nuclear density can be found, are very promising.In early theoretical investigations of this problem [1,2] one or another model of strong 1

Improved Hilbert moment thermal QCD sum rules for B_s meson and stability with respect to moment parameter

“…the annihilation and scattering parts of the thermal spectral density are obtained in the following forms [20]:…”

“…In the QCD side, the correlation function is evaluated with the help of operator product expansion (OPE). The thermal version of QCD sum rules has some new features compared to the one in vacuum [17][18][19][20][21]. The Lorentz invariance is broken in medium with the choice of the thermal rest frame.…”

Formation of light antinuclei and "dense gas" stage in heavy ion collisions

“…Similarly, due to interaction with medium constituents, the widths Γ i appear. The mass shift ∆m(E) and the width Γ(E) are expressed in terms of the forward scattering amplitude f (E) of the particle on i-th medium constituents (see [8,9] and references therein)…”

Mass shift, width broadening and spectral density of $rho;-mesons produced in heavy ion collisions

“…It is clear on physical grounds that the in-medium mass shift and width broadening of a particle are only due to its interaction with the constituents of the medium, for not too dense media anyway. Thus one can use phenomenological information on this interaction to calculate the mass shift and width broadening [1,2].For meson a scattering on hadron b in the medium the contribution to the self-energy is:where E and p are the energy and momentum of the meson, ω 2 = m 2 b + k 2 , n b is the occupation number, and f ab is the forward scattering amplitude. The normalization of the amplitude corresponds to the standard form of the optical theorem σ = (4π/q cm )Imf (cm) (s).…”

“…In the limit that the target particles b move nonrelativistically, Π ab = −4πf (b rest frame) ab ρ b , where ρ b is the spatial density. This corresponds to the mass shift and width broadening [2] …”