240 research outputs found
Different formulations of 3He and 3H photodisintegration
Different momentum space Faddeev-like equations and their solutions for the
radiative pd-capture and the three-nucleon photodisintegration of 3He are
presented. Applications are based on the AV18 nucleon-nucleon and the Urbana IX
three nucleon forces. Meson exchange currents are included using the Siegert
theorem. A very good agreement has been found in all cases indicating the
reliability of the used numerical methods. Predictions for cross sections and
polarization observables in the pd-capture and the complete three nucleon
breakup of 3He at different incoming deuteron/photon energies are presented.Comment: 18 pages, 9 ps figure
Hard exclusive wide-angle processes
In this talk the handbag approach to hard exclusive wide-angle processes is
reviewed and applications, as for instance two-photon annihilations into pairs
of mesons, are discussed.Comment: 11 pages, 8 figures, using latex2e, invited talk presented at Meson
2012, Cracow 201
A Three-Dimensional Treatment of the Three-Nucleon Bound State
Recently a formalism for a direct treatment of the Faddeev equation for the
three-nucleon bound state in three dimensions has been proposed. It relies on
an operator representation of the Faddeev component in the momentum space and
leads to a finite set of coupled equations for scalar functions which depend
only on three variables. In this paper we provide further elements of this
formalism and show the first numerical results for chiral NNLO nuclear forces.Comment: 25 pages, 7 figures (34 eps files
Exclusive meson pair production in proton-proton collisions
We present a study of the exclusive production of meson pairs in the
four-body , reactions at high
energies which constitute an irreducible background to resonance states (e.g.
, , , , ). We consider
central diffractive contribution mediated by Pomeron and Reggeon exchanges and
new diffractive mechanism of emission of pions/kaons from the proton lines. We
include absorption effects due to proton-proton interaction and pion/kaon
rescattering. Predictions for the total cross section and differential
distributions in pion/kaon rapidity and transverse momentum as well as
two-pion/kaon invariant mass are presented for the RHIC, Tevatron and LHC
colliders. Finally we consider a measurement of exclusive production of a
scalar meson via ,
decay.Comment: 4 pp., 4 figures, talk presented by PL at MESON2012 - 12th
International Workshop on Meson Production, Properties and Interaction,
Krakow, Poland, 31 May - 5 June 201
Exclusive production of and pairs in photon-photon and in ultrarelativistic heavy ion collisions
The reactions are discussed. To describe those
processes, we include dipion continuum, resonances, high-energy pion-pion
rescatterings, meson exchange and pQCD Brodsky-Lepage mechanisms. The
cross section for the production of pion pairs in photon-photon collisions in
peripheral heavy ion collisions is calculated with the help of Equivalent
Photon Approximaption (EPA) in the impact parameter space. We show predictions
at TeV which could be measured e.g. by the ALICE
collaboration at the LHC.Comment: 4 pages, 7 figures, 1 table, talk by M. Klusek-Gawenda at MESON2012,
31 May - 5 June 2012, Krakow, Polan
A Dispersive Treatment of Decays
are for several reasons an especially interesting decay channel
of mesons: decays allow an accurate measurement of a
combination of -wave scattering lengths, one form factor of the
decay is connected to the chiral anomaly and the decay is the best source for
the determination of some low energy constants of ChPT. We present a dispersive
approach to decays, which takes rescattering effects fully into
account. Some fits to NA48/2 and E865 measurements and results of the matching
to ChPT are shown.Comment: 4 pages, talk given by PS at MESON2012 - 12th International Workshop
on Meson Production, Properties and Interaction, Krak\'ow, Poland, 31 May - 5
June 201
Open charm meson production at LHC
We discuss charm production at the LHC. The production of single
pairs is calculated in the -factorization approach. We use
Kimber-Martin-Ryskin unintegrated gluon distributions in the proton. The
hadronization is included with the help of Peterson fragmentation functions.
Transverse momentum and pseudorapidity distributions of charmed mesons are
presented and compared to recent results of the ALICE, LHCb and ATLAS
collaborations. Furthermore we discuss production of two pairs of
within a simple formalism of double-parton scattering (DPS). Surprisingly large
cross sections, comparable to single-parton scattering (SPS), are predicted for
LHC energies. We discuss perspectives how to identify the double scattering
contribution. We predict much larger cross section for large rapidity distance
between charm quarks from different hard parton scatterings compared to single
scattering.Comment: 5 pages, 4 figures, talk given by R. Maciula at the MESON2012 - 12th
International Workshop on Meson Production, Properties and Interaction, 31
May - 5 June 2012, Krakow, Polan
eta' meson under partial restoration of chiral symmetry in nuclear medium
We shed light upon the eta' mass in nuclear matter in the context of partial
restoration of chiral symmetry, pointing out that the U_{A}(1) anomaly effects
causes the eta'-eta mass difference necessarily through the chiral symmetry
breaking. As a consequence, it is expected that the eta' mass is reduced by
order of 100 MeV in nuclear matter where partial restoration of chiral symmetry
takes place. The discussion given here is based on Ref. [1].Comment: 3 pages, 2 figures. Contribution to Meson201
Different Methods for the Two-Nucleon T-Matrix in the Operator Form
We compare three methods to calculate the nucleon-nucleon t-matrix based on
the three-dimensional formulation of J. Golak et al., Phys. Rev. C 81, 034006,
(2010). In the first place we solve a system of complex linear inhomogeneous
equations directly for the t-matrix. Our second method is based on iterations
and a variant of the Lanczos algorithm. In the third case we obtain the
t-matrix in two steps, solving a system of real linear equations for the
k-matrix expansion coefficients and then solving an on-shell equation, which
connects the scalar coefficients of the k- and t-matrices. A very good
agreement among the three methods is demonstrated for selected nucleon-nucleon
scattering observables using a chiral next-to-next-to-leading-order
neutron-proton potential. We also apply our three-dimensional framework to the
demanding problem of proton-proton scattering, using a corresponding version of
the nucleon-nucleon potential and supplementing it with the (screened) Coulomb
force, taken also in the three-dimensional form. We show converged results for
two different screening functions and find a very good agreement with other
methods dealing with proton-proton scattering.Comment: 18 pages, 10 figures (54 eps files
Strangeness production in antiproton-nucleus annihilation
The results of the microscopic transport calculations of -nucleus
interactions within a GiBUU model are presented. The dominating mechanism of
hyperon production is the strangeness exchange processes
and . The calculated rapidity spectra of hyperons are
significantly shifted to forward rapidities with respect to the spectra of
hyperons. We argue that this shift should be a sensitive test for the
possible exotic mechanisms of -nucleus annihilation. The production of
the double -hypernuclei by interaction with a secondary target
is calculated.Comment: Proceedings of the 12th Int. Workshop on Meson Production, Properties
and Interaction (MESON-2012), Cracow, 31.05-05.06.201
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