2,771 research outputs found
Coherent interactions of a fast proton with a short-range correlation in the nucleus
Nuclear structure at short -distances is still poorly understood. In
particular, the full quantum structure of the nucleus with a correlated
-pair is a challenge to theory. So far, model descriptions have been
limited to the average mean-field picture of the remaining nuclear system after
removing the -pair. In the recent experiment of the BM@N Collaboration at
JINR \cite{Patsyuk:2021fju}, the reactions
^{12}\mbox{C}(p,2pn_s)^{10}\mbox{B} and
^{12}\mbox{C}(p,2pp_s)^{10}\mbox{Be} induced by the hard elastic
scattering were studied. Here, or denote the undetected slow
nucleon in the rest frame of ^{12}\mbox{C}. In contrast to the previous
experiments, the residual bound nucleus was also detected which requires a new
level of theoretical understanding. In the present work, we apply the technique
of fractional parentage coefficients of the translationally-invariant shell
model (TISM) to calculate the spectroscopic amplitude of the system
where is the remaining nuclear system. The spectroscopic amplitude enters
the full amplitude of a nuclear reaction. The relative wave function is
no longer a free parameter of the model but is uniquely related to the internal
state of . The interaction of the target proton with the -pair is
considered in the impulse approximation. We also include the initial- and final
state interactions of absorptive type as well as the single charge exchange
processes. Our calculations are in a reasonable agreement with the BM@N data.Comment: 29 pages, 5 figures, 4 table
Possibility of cold nuclear compression in antiproton-nucleus collisions
We study the dynamical response of the oxygen-16 nucleus to an incident
antiproton using the Giessen Boltzmann-Uehling-Uhlenbeck microscopic transport
model with relativistic mean fields. A special emphasis is put on the
possibility of a dynamical compression of the nucleus induced by the moving
antiproton. Realistic antibaryon coupling constants to the mean meson fields
are chosen in accordance with empirical data. Our calculations show that an
antiproton embedded in the nuclear interior with momentum less than the nucleon
Fermi momentum may create a locally compressed zone in the nucleus with a
maximum density of about twice the nuclear saturation density. To evaluate the
probability of the nuclear compression in high-energy antiproton-nucleus
collisions, we adopt a two-stage scheme. This scheme takes into account the
antiproton deceleration due to the cascade of antiproton-nucleon rescatterings
inside the nucleus (first stage) as well as the nuclear compression by the slow
antiproton before its annihilation (second stage). With our standard model
parameters, the fraction of antiproton annihilation events in the compressed
zone is about for O collisions at
GeV/c. Finally, possible experimental triggers aimed at selecting such events
are discussed.Comment: 40 pages, 15 figures, new Sect. V on the in-medium modifications of
annihilation, modified conclusions, added references, version accepted in
Phys. Rev.
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