K+as a probe of partial deconfinement in nuclei

K+-nucleon amplitudes in the medium below 800 MeV/c

“…The enhancement of experimental total cross sections on C was already noted in 1985 by Siegel, Kaufmann and Gibbs [14] on the basis of very limited data. They showed that traditional calculations failed to produce the enhancement, thus suggesting more exotic mechanisms, see [3] for additional references.…”

Medium effects in K-nuclear interactions

“…Siegel et al [14] suggested that nucleon "swelling" in the medium primarily affects the dominant S 11 KN phase shift by increasing it in the nuclear medium. In the momentum range 500-700 MeV/c this amounts to increasing Im b 0 , as required by the data, but decreasing (the negative) Re b 0 contrary to the trend suggested by fitting to the data, of increasing it to become less repulsive.…”

“…These reaction and total cross sections provide 32 data points for the study of medium effects in K + nuclear interactions. It had been realized for the total cross sections data subset [12][13][14][15][16], and quite recently also for the reaction cross sections data subset [7,19], that the values of these integral cross sections, for the relatively dense C, Si and Ca nuclei, exceed substantially the predictions of the first-order optical potential V opt = tρ, by up to about 25%. This is inconceivable [13] for as weakly interacting hadron as the K meson is.…”

“…However, K + nucleus total cross section values [2][3][4][5][6][7] and reaction cross section values [7] derived from attenuation cross sections measured in transmission experiments, as well as elastic [8,9] and inelastic differential cross sections [8,10] and quasifree spectra [11], all point to a substantial departure of the order of 10-20% from the predictions of a simple tρ potential, even when many conventional nuclear medium effects are incorporated [12,13]. Several nonconventional medium effects have also been proposed to remedy the failure of the first-order optical potential approach, such as nucleon swelling [14], or density dependent vector meson masses [15], or polarizing the nuclear medium byNN excitations [16], or meson exchange currents [17,18], but as we shall discuss in the concluding section, none of these models provides a satisfactory solution to the discrepancy.…”

The theory of hadronic systems

“…We suggested a few years ago [36] that a possible way to study the modifications of the structure of the nucleon in a nuclear environment is to compare the total cross section of K+-nucleus scattering with K+-d scattering. Since 90% of the total cross section is given by single scattering this ratio will be sensitive to any changes in the K+-nucleon interaction in the nucleus.…”