366 research outputs found
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
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
Surface area or diameter – which factor really determines the antibacterial activity of silver nanoparticles grown on TiO₂ coatings?
Titanium dioxide coatings were prepared on Si wafers using the sol–gel method. Four different types of coatings with silver nanoparticles (AgNPs) were synthesized. The diameter and surface density of AgNPs were conditioned by the concentration of Ag+ ions in the initial solution, time and UV illumination source. The bactericidal activity of AgNPs on the titanium dioxide coatings against the S. aureus strain were calculated as the percentage of the inhibition of bacterial growth after 24 hour incubation of microorganisms at 37°C on TiO₂ coatings with AgNPs. Control samples were coated with titanium dioxide without AgNPs. We concluded that the titanium dioxide coatings modified with silver nanoparticles had a high antibacterial activity. Moreover, we demonstrated strong dependence between surface areas of AgNPs and inhibition of bacterial growth. The obtained results evidence that the surface area of AgNPs grown on titanium dioxide coatings is a major factor determining their antimicrobial potential
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
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
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
Hadron Spectroscopy with COMPASS -- Newest Results
The COMPASS experiment at the CERN SPS investigates the structure and
spectrum of hadrons by scattering high energetic hadrons and polarised muons
off various fixed targets. During the years 2002-2007, COMPASS focused on
nucleon spin physics using 160 GeV/c polarised beams on polarised
deuteron and proton targets, including measurements of the gluon contribution
to the nucleon spin using longitudinal target polarisation as well as studies
of transverse spin effects in the nucleon on a transversely polarised target.
One major goal of the physics programme using hadron beams is the search for
new states, in particular the search for exotic states and glue-balls.
COMPASS measures not only charged but also neutral final-state particles,
allowing for investigation of new objects in different reactions and decay
channels. In addition COMPASS can measure low-energy QCD constants like, e.g.
the electromagnetic polarisability of the pion. Apart from a few days pilot run
data taken in 2004 with a 190 GeV/c beam on a Pb target, showing a
significant spin-exotic = resonance at around 1660
MeV/, COMPASS collected high statistics with negative and positive 190
GeV/ hadron beams on a proton (H) and nuclear (Ni, Pb) targets in 2008
and 2009. We give a selected overview of the newest results and discuss the
status of various ongoing analyses.Comment: 7 pages, 13 figures, MESON2012 Conference Proceedings, to appear in
the proceedings of the 12th International Workshop on Meson Production,
Properties and Interaction, KRAK\'OW, POLAND, 31 May - 5 June 201
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