27 research outputs found
High energy cosmic rays in the low stratosphere and extrapolation above LHC energies
We review the data obtained with the emulsion chambers boarded on Concorde for the events collected above 106 GeV and their specific properties (large multiplicities, multiclusters, coplanar emission): the main features are compared to the expectation of our HDPM2 Monte Carlo collision generator. This multiproduction event generator has been adjusted and tuned, according to the
pseudo-rapidity distributions recently observed at √s = 630 GeV, as well as to previous Fermi-lab results at √s = 1800 GeV: an increase of the total inelasticity (0.72 for NSD component) near the knee region and a more important violation than usually expected for Feynman’s scaling in forward region are observed. In such cirumstance, we have
simulated large and giant air showers taking into account, in addition, new processes, such as diquark breaking, up to energies exceeding 1020 eV for P.AUGER and EUSO experiments
Compton scattering beyond the impulse approximation
We treat the non-relativistic Compton scattering process in which an incoming
photon scatters from an N-electron many-body state to yield an outgoing photon
and a recoil electron, without invoking the commonly used frameworks of either
the impulse approximation (IA) or the independent particle model (IPM). An
expression for the associated triple differential scattering cross section is
obtained in terms of Dyson orbitals, which give the overlap amplitudes between
the N-electron initial state and the (N-1) electron singly ionized quantum
states of the target. We show how in the high energy transfer regime, one can
recover from our general formalism the standard IA based formula for the cross
section which involves the ground state electron momentum density (EMD) of the
initial state. Our formalism will permit the analysis and interpretation of
electronic transitions in correlated electron systems via inelastic x-ray
scattering (IXS) spectroscopy beyond the constraints of the IA and the IPM.Comment: 7 pages, 1 figur
Large Transverse Momenta in Statistical Models of High Energy Interactions
The creation of particles with large transverse momenta in high energy
hadronic collisions is a long standing problem. The transition from small-
(soft) to hard- parton scattering `high-pt' events is rather smooth. In this
paper we apply the non-extensive statistical framework to calculate transverse
momentum distributions of long lived hadrons created at energies from low
(sqrt(s)~10 GeV) to the highest energies available in collider experiments
(sqrt(s)~2000 GeV). Satisfactory agreement with the experimental data is
achieved. The systematic increase of the non-extensivity parameter with energy
found can be understood as phenomenological evidence for the increased role of
long range correlations in the hadronization process.
Predictions concerning the rise of average transverse momenta up to the
highest cosmic ray energies are also given and discussed.Comment: 20 pages, 10 figure
Markovian Equilibrium in Infinite Horizon Economies with Incomplete Markets and Public Policy
We develop an isotone recursive approach to the problem of existence, computation, and characterization of nonsymmetric locally Lipschitz continuous (and, therefore, Clarke-differentiable) Markovian equilibrium for a class of infinite horizon multiagent competitive equilibrium models with capital, aggregate risk, public policy, externalities, one sector production, and incomplete markets. The class of models we consider is large, and examples have been studied extensively in the applied literature in public economics, macroeconomics, and financial economics. We provide sufficient conditions that distinguish between economies with isotone Lipschitizian Markov equilibrium decision processes (MEDPs) and those that have only locally Lipschitzian (but not necessarily isotone) MEDPs. As our fixed point operators are based upon order continuous and compact non-linear operators, we are able to provide sufficient conditions under which isotone iterative fixed point constructions converge to extremal MEDPs via successive approximation. We develop a first application of a new method for computing MEDPs in a system of Euler inequalities using isotone fixed point theory even when MEDPs are not necessarily isotone. The method is a special case of a more general mixed monotone recursive approach. We show MEDPs are unique only under very restrictive conditions. Finally, we prove monotone comparison theorems in Veinott's strong set order on the space of public policy parameters and distorted production functions
3D-electron momentum density of graphite
The complete 3D-electron momentum density (EMD) of solids can be measured by the coincident detection of an inelastically scattered hard X-ray photon and its recoil electron (i.e. a so-called (γ,eγ) experiment). To avoid multiple scattering of the recoil electron the experiment has been performed with a 22 nm thin graphite foil made by laser plasma ablation. The experimental EMD is compared with a pseudopotential calculation. Experiments have been made both at the European Synchrotron Radiation Facility at Grenoble, France, and at the PETRA storage ring of DESY, Hamburg, Germany
3D-electron momentum density of graphite
The complete 3D-electron momentum density (EMD) of solids can
be measured by the coincident detection of an inelastically scattered hard
X-ray photon and its recoil electron (i.e. a so-called ()
experiment). To avoid multiple scattering of the recoil electron the experiment has
been performed with a 22Â nm thin graphite foil made by laser plasma ablation.
The experimental EMD is compared with a pseudopotential calculation. Experiments
have been made both at the European Synchrotron Radiation Facility at Grenoble,
France, and at the PETRA storage ring of DESY, Hamburg, Germany
Electron momentum density of graphite from () spectroscopy
By the coincidental detection of an inelastically scattered hard X-ray photon and its recoil electron (i.e. a so-called (γ,eγ) experiment) cuts through the 3D-electron momentum density (EMD) of graphite have been measured and are compared with a theoretical EMD based on a pseudopotential calculation. Peak shifts of the EMD as a function of the electron emission angle are discussed by a detailed consideration of the scattering kinematics. Experiments have been performed at the European Synchrotron Radiation Facility (ESRF) at Grenoble, France
Three-dimensional electron momentum densities:A comparison of () and () spectroscopies
We report on the comparison of a (γ,eγ) with an (e,2e) experiment made with the same 17-nm thin graphite foil. The energies of the projectile, scattered projectile, and recoil electron were 174.5, 108.9, and 65.6 keV in the case of the (γ,eγ) experiment and 20, 18.8, and 1.2 keV for the (e,2e) study. In the coincident (e,2e) energy-loss spectra, two distinct peaks are observed which are attributed to σ and π electrons. If the spectral momentum density of the (e,2e) experiment is integrated over the energy loss, the resulting momentum density can be compared directly with the (γ,eγ) result. Good overall agreement is observed between both methods and the resulting three-dimensional electron momentum density is well reproduced by both a pseudopotential and density-functional calculation. The remaining differences between the (e,2e) and (γ,eγ) results are discussed in terms of multiple elastic electron scattering, which might affect the (e,2e) data