88 research outputs found
Study of the quasi-free reaction with a deuterium beam at 1.25 GeV/nucleon
The tagged quasi-free reaction has been studied
experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI
at a deuteron incident beam energy of 1.25 GeV/nucleon ( 2.42
GeV/c for the quasi-free collision). For the first time, differential
distributions for production in collisions have been
collected in the region corresponding to the large transverse momenta of the
secondary particles. The invariant mass and angular distributions for the
reaction are compared with different models.
This comparison confirms the dominance of the -channel with
contribution. It also validates the changes previously introduced in the
Valencia model to describe two-pion production data in other isospin channels,
although some deviations are observed, especially for the
invariant mass spectrum. The extracted total cross section is also in much
better agreement with this model. Our new measurement puts useful constraints
for the existence of the conjectured dibaryon resonance at mass M 2.38
GeV and with width 70 MeV
Deuteron-Proton Elastic Scattering at Intermediate Energies
The deuteron-proton elastic scattering has been studied in the multiple
scattering expansion formalism. The essential attention has been given to such
relativistic problem as a deuteron wave function in a moving frame and
transformation of spin states due to Wigner rotation. Parameterization of the
nucleon-nucleon -matrix has been used to take the off-energy shell effects
into account. The vector, and tensor, , analyzing powers of the
deuteron have been calculated at two deuteron kinetic energies: 395 MeV and
1200 MeV. The obtained results are compared with the experimental data
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
Strange hadron production at SIS energies: an update from HADES
We present and discuss recent experimental activities of the HADES collaboration on open and hidden strangeness production close or below the elementary NN threshold. Special emphasis is put on the feed-down from ϕ mesons to antikaons, the presence of the Ξ(-) excess in cold nuclear matter and the comparison of statistical model rates to elementary p+p data. The implications for the interpretation of heavy-ion data are discussed as well
Resonance production in p+p, p+A and A+A collisions measured with HADES
The knowledge of baryonic resonance properties and production cross sections plays an important role for the extraction and understanding of medium modifications of mesons in hot and/or dense nuclear matter. We present and discuss systematics on dielectron and strangeness production obtained with HADES on p+p, p+A and A+A collisions in the few GeV energy regime with respect to these resonances
Differential Cross Section of DP-Elastic Scattering at Intermediate Energies
The deuteron-proton elastic scattering is studied in the multiple scattering
expansion formalism. The contributions of the one-nucleon-exchange, single- and
double scattering are taken into account. The Love and Franey parameterization
of the nucleon-nucleon -matrix is used, that gives an opportunity to include
the off-energy-shell effects into calculations. Differential cross sections are
considered at four energies, MeV. The obtained
results are compared with the experimental data
New data on the differential cross section of the dp-elastic scattering at 2.5 GeV obtained with HADES detector
New results on the differential cross section in deuteron-proton elastic scattering are obtained at the deuteron kinetic energy of 2.5 GeV with the HADES spectrometer. The angular range of 69°-125° in the center of mass system is covered. The obtained results are compared with the relativistic multiple scattering model calculation using the CD-Bonn deuteron wave function. The data at fixed scattering angles in the c.m. are in qualitative agreement with the constituent counting rules prediction
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