Paramagnonlike excitations and spin diffusion in magnetic resonance studies of copper oxide superconductors

The relaxation function theory for a doped two-dimensional Heisenberg antiferromagnetic system in the paramagnetic state for all wave vectors through the Brillouin zone is presented in view of low frequency response of high-$T_c$ copper oxide superconductors. We deduced the regions of long lifetime [$T \lesssim 400(1-4x)$ K] and "overdamped" [$T \gtrsim 700(1-4x)$ K] paramagnonlike excitations in the temperature ($T$)-doping index ($x$) phase diagram from plane oxygen nuclear spin-lattice relaxation rate $^{17}(1/T_1)$ data in up to optimally doped La$_{2-x}$Sr$_{x}$CuO$_{4}$ thus providing the regimes for the spin wave concept and the ''overdamped'' mode.Comment: Physical Review B, accepted, in pres

Exploring QCD dynamics in medium energy γA\gamma A semiexclusive collisions

We demonstrate that studies of the semiexclusive large angle photon - nucleus reactions: $\gamma + A\to h_1+h_2 +(A-1)^*$ with tagged photon beams of energies $6 \div 10$ GeV which can be performed in Hall D at Thomas Jefferson National Acceleration Facility (TJNAF) would allow to probe several aspects of the QCD dynamics: establish the $t$-range in which transition from soft to hard dynamics occurs, compare the strength of the interaction of various mesons and baryons with nucleons at the energies of few GeV, as well as look for the color transparency effects.Comment: 13 pages, 6 figures, minor revisions, version accepted in Phys. Lett.

Determination of the structure of the X(3872)X(3872) in pˉA\bar p A collisions

Currently, the structure of the $X(3872)$ meson is unknown. Different competing models of the $c\bar c$ exotic state $X(3872)$ exist, including the possibilities that this state is either a mesonic molecule with dominating $D^0 \bar D^{*0} +c.c.$ composition, a $c \bar c q \bar q$ tetraquark, or a $c \bar c$-gluon hybrid state. It is expected that the $X(3872)$ state is rather strongly coupled to the $\bar p p$ channel and, therefore, can be produced in $\bar p p$ and $\bar pA$ collisions at PANDA. We propose to test the hypothetical molecular structure of $X(3872)$ by studying the $D$ or $\bar D^{*}$ stripping reactions on a nuclear residue.Comment: 19 pages, 8 figures; version accepted in PL

Kaon production from 1 to 40 A GeV

Kaon production is studied within the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) model. Results are compared with experiment and with other models. The influence of the kaon potential on the kaon azimuthal distributions at SIS energies is considered. We also discuss the role of the many-body collisions at high-density phase of reaction.Comment: 6 pages, 4 figures, Proc. of the Int. Workshop on Hot and Dense Matter in Relativistic Heavy Ion Collisions, 09-12.04.2006, Budapes