383 research outputs found
Rescattering effects in antiproton-induced exclusive and production on the deuteron
On the basis of the generalized eikonal approximation we study the exclusive
reactions and in
vicinity of the thresholds for charmonium production on a free proton target.
It is shown that the rescattering of the incoming antiproton and outgoing
charmonium on the spectator neutron leads to a depletion of the charmonium
production at low- and to an enhancement at high transverse momenta. This is in
qualitative agreement with previous studies of hard proton knockout in
proton-deuteron collisions. We analyze different physical sources of
uncertainty which may influence the extraction of the total charmonium-neutron
cross section. The color transparency effect for the incoming largely
compensates the influence of charmonium rescattering both at low and high
transverse momenta. Different choices of the deuteron wave function lead to
significant uncertainties at high transverse momenta. As an outcome of the
calculations of charmonium production, we also provide predictions on the
production of open charm hadrons due to the dissociation of the charmonium on
the neutron. It is shown that the open charm production cross section is
proportional to the total charmonium-nucleon cross section and quite stable
with respect to the variation of other parameters of the model. We thus suggest
that open charm channels are most suited for future studies of
charmonium-nucleon interactions at PANDA with a deuteron target.Comment: 28 pages, 8 figures, modified sec. 1 and 2, new Fig. 2, added
references, results unchanged, version accepted in EPJ
Formation of -mesic Nuclei Using the Recoilless (d,He) Reaction
We propose to use the recoilless (d,He) reaction to produce -mesic
nuclei. This reaction has been used to observe deeply bound pionic states and
proven to be powerful recently. We calculate -mesic bound states in the
nucleus using an optical potential and their formation cross section with the
Green function method. Then, we carefully check the experimental feasibility.
We find that -mesic nuclei can be observed experimentally using the
(d,He) reaction. We also mention the possibility to study the formation of
-mesic nuclei.Comment: 15 pages, 6 eps figures, Late
Theoretical study of the configuration in the deuteron using antiproton beam
We study the manifestation of the component of the
deuteron wave function in the exclusive reaction . Due to the large binding energy the internal motion in the
system is relativistic. We take this into account within the
light-cone (LC) wave function formalism and, indeed, found large differences
between calculations based on the LC and non-relativistic (NR) wave functions.
We demonstrate, that the consistent LC treatment of the system
plays the key role in the separation of the signal and background. Within the
LC approach, the characteristic shape of the momentum distribution of the
bound system predicted by the meson-exchange model is well
visible on the background of usual annihilations at beam momenta between 10 and
15 GeV/c.Comment: 44 pages, 21 figures, sect. 3 extended, references added, results
unchanged, accepted in Phys. Rev.
Extracting the depolarization coefficient D_NN from data measured with a full acceptance detector
The spin transfer from vertically polarized beam protons to Lambda or Sigma
hyperons of the associated strangeness production pp -> pK Lambda (Sigma) is
described with the depolarization coefficient D_NN. As the polarization of the
hyperons is determined by their weak decays, detectors, which have a large
acceptance for the decay particles, are needed. In this paper a formula is
derived, which describes the depolarization coefficient D_NN by count rates of
a 4 pi detector. It is shown, that formulas, which are given in publications
for detectors with restricted acceptance, are specific cases of this formula
for a 4 pi detector.Comment: Accepted for publication by Nuclear Instruments and Methods in
Physics Research Section
A recoil detector for the measurement of antiproton-proton elastic scattering at angles close to 90
The design and construction of a recoil detector for the measurement of
recoil protons of antiproton-proton elastic scattering at scattering angles
close to 90 are described. The performance of the recoil detector has
been tested in the laboratory with radioactive sources and at COSY with proton
beams by measuring proton-proton elastic scattering. The results of laboratory
tests and commissioning with beam are presented. Excellent energy resolution
and proper working performance of the recoil detector validate the conceptual
design of the KOALA experiment at HESR to provide the cross section data needed
to achieve a precise luminosity determination at the PANDA experiment.Comment: 10 pages, 15 figure
Essays in Macroeconomics and Public Finance.
This dissertation contains three chapters at the intersection of macroeconomics and public finance.
The first chapter demonstrates that deep recessions can stimulate investment in state fiscal capacity. Large negative income shocks endanger the revenue-raising capability of existing narrow tax bases, particularly when the ability to borrow is limited, making an increase in fiscal capacity desirable relative to its implementation cost. An increase in fiscal capacity enables a given amount of revenue to be raised by taxing a wider range of economic activity at lower tax rates, which reduces the efficiency cost of taxation. Evidence from U.S. state governments during the Great Depression supports the model's predictions: governments in states experiencing larger than average negative income shocks were significantly more likely to adopt a retail sales tax (and income taxes) than were governments in states experiencing smaller than average income shocks, and state governments entering the Great Depression with a high level of debt were more likely to adopt new tax bases than those with low levels of debt.
The second chapter proposes a model of consumption commitments - costly adjustment of spending for some goods - that can be easily incorporated into an otherwise standard representative agent DSGE model. The model explains several features of aggregate consumption data: (i) excess smoothness and excess sensitivity; (ii) hump-shaped dynamics; (iii) attenuated response to transitory real interest rate changes; and (iv) some aspects of the equity-premium puzzle. The model provides a microfoundation for reference dependent consumption.
The third chapter, co-authored with Peer Skov, uses a reform in Denmark affecting reporting of charitable tax deductions to shed light on taxpayer behavior. We find that the introduction of information reporting and pre-population of charitable tax deductions in 2008 coincided with a doubling in the number of deductions claimed, and attribute this change to incomplete claiming of eligible deductions under the prior self-reporting regime. We estimate the per-year average amount of forgone tax benefits to be small, but find that many taxpayers repeatedly failed to claim eligible charitable tax deductions under the self-reporting regime.PhDEconomicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102360/1/cgillitz_1.pd
Precision spectroscopy of pionic 1s states of Sn nuclei and evidence for partial restoration of chiral symmetry in the nuclear medium
Deeply bound 1s states of in Sn were preferentially
observed using the Sn(,He) pion-transfer reaction under the recoil-free
condition. The 1s binding energies and widths were precisely determined, and
were used to deduce the isovector parameter of the s-wave pion-nucleus
potential to be . The observed enhancement
of over the free value ()
indicates a reduction of the chiral order parameter, , at the normal nuclear density, .Comment: 4 pages including 3 postscript figures, RevTeX 4 with multirow.sty,
submitted to Physical Review Letter
High precision measurement of the associated strangeness production in proton proton interactions
A new high precision measurement of the reaction pp -> pK+Lambda at a beam
momentum of 2.95 GeV/c with more than 200,000 analyzed events allows a detailed
analysis of differential observables and their inter-dependencies. Correlations
of the angular distributions with momenta are examined. The invariant mass
distributions are compared for different regions in the Dalitz plots. The cusp
structure at the N Sigma threshold is described with the Flatt\'e formalism and
its variation in the Dalitz plot is analyzed.Comment: accepted for publication in Eur. Phys. J.
First Model-Independent Measurement of the Spin Triplet Scattering Length from Final State Interaction in the Reaction
The reaction has been measured with the
COSY-TOF detector at a beam momentum of . The polarized
proton beam enables the measurement of the beam analyzing power by the
asymmetry of the produced kaon (). This observable allows the
spin triplet scattering length to be extracted for the first time
model independently from the final-state interaction in the reaction. The
obtained value is . This value is
compatible with theoretical predictions and results from model-dependent
analyses.Comment: Revised version as accepted for publication in PR
- …