Photoproduction of Z(4430) through mesonic Regge trajectories exchange

The recently discovered Z(4430) mesonic resonance is believed to be a strong tetraquark candidate. The photoproduction in the channel $\gamma p\rightarrow Z^{+}(4430)n\rightarrow \psi ' \pi^{+} n$ has been proposed as the most effective way to confirm the Z(4430) presence and to measure its quantum numbers. In this work we present a model for high energy and forward angle Z(4430) photoproduction in a effective Lagrangian approach. This model is based on the use of Regge trajectories exchange, thus a Regge propagator replaces the usual Feynman propagator. The differential and total cross sections and the asymmetries have been calculated for the $J^{P}$ quantum numbers $1^{-}$, $1^{+}$, $0^{-}$ and $2^{-}$ in the hypotheses that Z(4430) has isospin I=1

Higher order QED in high mass e+ e- pairs production at RHIC

Lowest order and higher order QED calculations have been carried out for the RHIC high mass e+ e- pairs observed by PHENIX with single ZDC triggers. The lowest order QED results for the experimental acceptance are about two standard deviations larger than the PHENIX data. Corresponding higher order QED calculations are within one standard deviation of the data.Comment: 2 page

Impact of forestry practices on fitness correlates and population productivity in an open-nesting bird species

In the boreal forests of Fennoscandia, over 99% of the forest area has been altered by forestry practices, which has created forests of differing age structures and stand characteristics than primary forest stands. Although many researchers have investigated how forestry affects species abundance, few have assessed how forestry affects fitness correlates of species living in altered habitats, and this has negatively affected management efforts. We experimentally addressed the effect of standard forestry practices on fitness correlates of an open-nesting, long-lived bird species typical to boreal forests of Eurasia, the Siberian Jay (Perisoreus infaustus L.). Using a before-after comparison of reproductive data on the level of territories, we found that standard forestry practices had a strong negative effect on the breeding success of jays. Both partial thinning of territories and partial clearcutting of territories reduced future breeding success by a factor of 0.35. Forestry practices reduced territory occupancy. Thus, over the 15 years of the study the productivity of the affected population declined over 50% as a result of territory abandonment and reduced breeding success. Results of previous studies on Siberian Jays suggest that the strong effect of forest thinning on fitness is explained by the fact that most common predators of nests and adults are visually oriented, and thinning makes prey and nests more visible to predators. The consequences of thinning we observed are likely to apply to a wide range of species that rely on understory to provide visual protection from predators. Thus, our results are important for the development of effective conservation management protocols and for the refinement of thinning practices

Aspects of Coulomb Dissociation and Interference in Peripheral Nucleus-Nucleus Collisions

Coherent vector meson production in peripheral nucleus-nucleus collisions is discussed. These interactions may occur for impact parameters much larger than the sum of the nuclear radii. Since the vector meson production is always localized to one of the nuclei, the system acts as a two-source interferometer in the transverse plane. By tagging the outgoing nuclei for Coulomb dissociation it is possible to obtain a measure of the impact parameter and thus the source separation in the interferometer. This is of particular interest since the life-time of the vector mesons are generally much shorter than the impact parameters of the collisions.Comment: 10 pages, 4 figures, Presented at the Workshop on Electromagnetic Probes of Fundamental Physics, Erice, Italy, 16-21 October, 200

Two-Photon Interactions with Nuclear Breakup in Relativistic Heavy Ion Collisions

Highly charged relativistic heavy ions have high cross-sections for two-photon interactions. The photon flux is high enough that two-photon interactions may be accompanied by additional photonuclear interactions. Except for the shared impact parameter, these interactions are independent. Additional interactions like mutual Coulomb excitation are of experimental interest, since the neutrons from the nuclear dissociation provide a simple, relatively unbiased trigger. We calculate the cross sections, rapidity, mass and transverse momentum ($p_T)$ distributions for exclusive $\gamma\gamma$ production of mesons and lepton pairs, and for $\gamma\gamma$ reactions accompanied by mutual Coulomb dissociation. The cross-sections for $\gamma\gamma$ interactions accompanied by multiple neutron emission ($XnXn$) and single neutron emission ($1n1n$) are about 1/10 and 1/100 of that for the unaccompanied $\gamma\gamma$ interactions. We discuss the accuracy with which these cross-sections may be calculated. The typical $p_T$ of $\gamma\gamma$ final states is several times smaller than for comparable coherent photonuclear interactions, so $p_T$ may be an effective tool for separating the two classes of interactions.Comment: 17 pages, 12 figure

Photoproduction of Quarkonium in Proton-Proton and Nucleus-Nucleus Collisions

We discuss the photoproduction of $\Upsilon$ and $J/\psi$ at high energy $\bar{p}p$, $pp$ and heavy ion colliders. We predict large rates in $\bar{p}p$ interactions at the Fermilab Tevatron %and in heavy-ion interactions at the CERN LHC. These reactions can be and in $pp$ and heavy-ion interactions at the CERN LHC. The $J/\psi$ is also produced copiously at RHIC. These reactions can be used to study the gluon distribution in protons and heavy nuclei. We also show that the different CP symmetries of the initial states lead to large differences in the transverse momentum spectra of mesonsComment: 4 pgs. with 3 figure

Interference in Exclusive Vector Meson Production in Heavy Ion Collisions

Photons emitted from the electromagnetic fields of relativistic heavy ions can fluctuate into quark anti-quark pairs and scatter from a target nucleus, emerging as vector mesons. These coherent interactions are identifiable by final states consisting of the two nuclei and a vector meson with a small transverse momentum. The emitters and targets can switch roles, and the two possibilities are indistinguishable, so interference may occur. Vector mesons are negative parity so the amplitudes have opposite signs. When the meson transverse wavelength is larger than the impact parameter, the interference is large and destructive. The short-lived vector mesons decay before amplitudes from the two sources can overlap, and so cannot interfere directly. However, the decay products are emitted in an entangled state, and the interference depends on observing the complete final state. The non-local wave function is an example of the Einstein-Podolsky-Rosen paradox.Comment: 13 pages with 3 figures; submitted to Physical Review Letter

PHENIX measurement of jet properties and their modification in heavy-ion collisions

The properties of jets produced in p+p, d+Au and Au+Au collisions at sqrt{s_NN}=200 GeV are studied using the method of two particle correlations. The trigger particle is assumed to be a leading particle from a high p_T jet while the associated particle is assumed to come from either the same jet or the away jet. From the angular width and yield of the same and away side correlation peaks, the parameters characterizing the jet properties are extracted.Comment: 4 pages, 3 figures, contribution to the proceedings of the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter, Oakland, January 11-17, 2004). To appear in the proceedings (Journal of Physics G

Traces of Thermalization from Transverse Momentum Fluctuations in Nuclear Collisions

Scattering of particles produced in Au+Au collisions at RHIC can wrestle the system into a state near local thermal equilibrium. I illustrate how measurements of the centrality dependence of the mean transverse momentum and its fluctuations can exhibit this thermalization.Comment: 4 pages, 2 eps figures, final version to appear in PR