283 research outputs found

    Essays in Macroeconomics and Public Finance.

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    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

    Extracting the depolarization coefficient D_NN from data measured with a full acceptance detector

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    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^{\circ}

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    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^{\circ} 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

    Search for He-eta bound states with the WASA-at-COSY facility

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    The existence of eta-mesic nuclei in which the eta meson is bound in a nucleus by means of the strong interaction was postulated already in 1986, albeit not yet confirmed it by experiment. The discovery of this new kind of an exotic nuclear matter would be very important as it might allow for a better understanding of the eta meson structure and its interaction with nucleons. The search for eta-mesic helium 4He-eta is carried out with high statistics and high acceptance with the WASA detector, installed at the cooler synchrotron COSY of the Research Center Juelich. The search is conducted via the measurement of the excitation function for selected decay channels of the 4He-eta system. In the experiment, performed in November 2010, two reactions dd->(4He-eta)bs ->3He p pi- and dd->(4He-eta)bs ->3He p pi0 were measured with a beam momentum ramped from 2.127GeV/c to 2.422GeV/c. The report includes the description of the experimental method and status of the measurement.Comment: Presented at the Erice School on Nuclear Physics 2011. 5 pages, 3 figure

    High precision measurement of the associated strangeness production in proton proton interactions

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    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 pΛp\Lambda Scattering Length from Final State Interaction in the pppK+Λ\vec{p}p \rightarrow pK^{+}\Lambda Reaction

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    The pppK+Λ\vec{p}p \rightarrow pK^{+}\Lambda reaction has been measured with the COSY-TOF detector at a beam momentum of 2.7GeV/c2.7\,\mathrm{GeV}/c. The polarized proton beam enables the measurement of the beam analyzing power by the asymmetry of the produced kaon (ANKA_N^{K}). This observable allows the pΛp\Lambda 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 at=(2.551.39+0.72stat.±0.6syst.±0.3theo.)fma_{t} = (-2.55 ^{+0.72}_{-1.39} {}_{\textrm{stat.}} \pm 0.6_{\textrm{syst.}} \pm 0.3_{\textrm{theo.}})\mathrm{fm}. This value is compatible with theoretical predictions and results from model-dependent analyses.Comment: Revised version as accepted for publication in PR

    Precision spectroscopy of pionic 1s states of Sn nuclei and evidence for partial restoration of chiral symmetry in the nuclear medium

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    Deeply bound 1s states of π\pi^- in 115,119,123^{115,119,123}Sn were preferentially observed using the Sn(dd,3^3He) 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 b1=0.115±0.007 mπ1b_1 =-0.115\pm 0.007 ~m_{\pi}^{-1}. The observed enhancement of b1|b_1| over the free πN\pi N value (b1free/b1=0.78±0.05b_1^{\rm free}/b_1 = 0.78 \pm 0.05) indicates a reduction of the chiral order parameter, fπ(ρ)2/fπ20.64f^{*}_{\pi} (\rho)^2/f_{\pi}^2 \approx 0.64, at the normal nuclear density, ρ=ρ0\rho = \rho_0.Comment: 4 pages including 3 postscript figures, RevTeX 4 with multirow.sty, submitted to Physical Review Letter

    Single \pi^- production in np collisions for excess energies up to 90 MeV

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    The quasifree reaction np\to pp\pim was studied in a kinematically complete experiment by bombarding a liquid hydrogen target with a deuteron beam of momentum 1.85 GeV/c and analyzing the data along the lines of the spectator model. In addition to the three charged ejectiles the spectator proton was also detected in the large-acceptance time-of-flight spectrometer COSY-TOF. It was identified by its momentum and flight direction thus yielding access to the Fermi motion of the bound neutron and to the effective neutron 4-momentum vector Pn\mathbb{P}_n which differed from event to event. A range of almost 90 MeV excess energy above threshold was covered. Energy dependent angular distributions, invariant mass spectra as well as fully covered Dalitz plots were deduced. Sizeable pppp FSI effects were found as were contributions of pp and dd partial waves. The behavior of the elementary cross section σ01\sigma_{01} close to threshold is discussed in view of new cross section data. In comparison with existing literature data the results provide a sensitive test of the spectator model.Comment: 21 pages, 9 figures, 4 tables, submitted to EPJ
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