7,347,266 research outputs found
On kaonic hydrogen. Quantum field theoretic and relativistic covariant approach
We study kaonic hydrogen, the bound K^-p state A_(Kp). Within a quantum field
theoretic and relativistic covariant approach we derive the energy level
displacement of the ground state of kaonic hydrogen in terms of the amplitude
of K^-p scattering for arbitrary relative momenta. The amplitude of low-energy
K^-p scattering near threshold is defined by the contributions of three
resonances Lambda(1405), Lambda(1800) and Sigma^0(1750) and a smooth elastic
background. The amplitudes of inelastic channels of low-energy K^-p scattering
fit experimental data on near threshold behaviour of the cross sections and the
experimental data by the DEAR Collaboration. We use the soft-pion technique
(leading order in Chiral Perturbation Theory) for the calculation of the
partial width of the radiative decay of pionic hydrogen A_(pi p) -> n + gamma
and the Panofsky ratio. The theoretical prediction for the Panofsky ratio
agrees well with experimental data. We apply the soft-kaon technique (leading
order in Chiral Perturbation Theory) to the calculation of the partial widths
of radiative decays of kaonic hydrogen A_(Kp) -> Lambda^0 + gamma and A_(Kp) ->
Sigma^0 + gamma. We show that the contribution of these decays to the width of
the energy level of the ground state of kaonic hydrogen is less than 1%.Comment: 33 pages, 1 figure, latex, References are adde
Electronic structure of the incommensurate compound
We extracted, from strongly-correlated ab-initio calculations, a complete
model for the chain subsystem of the
incommensurate compound. A second neighbor model has been determined as
a function of the fourth crystallographic parameter , for both low and
room temperature crystallographic structures. The analysis of the obtained
model shows the crucial importance of the structural modulations on the
electronic structure through the on-site energies and the magnetic
interactions. The structural distortions are characterized by their long range
effect on the cited parameters that hinder the reliability of analyses such as
BVS. One of the most striking results is the existence of antiferromagnetic
nearest-neighbor interactions for metal-ligand-metal angles of . A
detailed analysis of the electron localization and spin arrangement is
presented as a function of the chain to ladder hole transfer and of the
temperature. The obtained spin arrangement is in agreement with
antiferromagnetic correlations in the chain direction at low temperature
Reconclining phi radiative decays with other data for a0(980), fo(980), pi-pi -> KK and pi-pi -> eta-eta
Data for phi -> gamma (eta-pizero) are analysed using the KK loop model and
compared with parameters of a0(980) derived from Crystal Barrel data. The
eta-pi mass spectrum agrees closely and the absolute normalisation lies just
within errors. However, BES parameters for fo(980) predict a normalisation for
phi -> gamma (pizero-pizero) at least a factor 2 lower than is observed. This
discrepancy may be eliminated by including constructive interference between
fo(980) and sigma. The magnitude required for sigma -> KK is consistent with
data on pi-pi -> KK. A dispersion relation analysis by Buttiker, Descotes-Genon
and Moussallam of pi-pi -> KK leads to a similar conclusion. Data on pi-pi ->
eta-eta also require decays of sigma to eta-eta. Four sets of pi-pi -> KK data
all require a small but definite fo(1370) signal.Comment: 21 pages, 11 figures, Small rearrangement of reference
NN final-state interaction in two-nucleon knockout from
The influence of the mutual interaction between the two outgoing nucleons
(NN-FSI) in electro- and photoinduced two-nucleon knockout from has
been investigated perturbatively. It turns out that the effect of NN-FSI
depends on the kinematics and on the type of reaction considered. The effect is
generally larger in pp- than in pn-knockout and in electron induced than in
photoinduced reactions.
In superparallel kinematics NN-FSI leads in the channel to a
strong increase of the cross section, that is mainly due to a strong
enhancement of the -current contribution. In pn-emission, however, this
effect is partially cancelled by a destructive interference with the seagull
current. For photoreactions NN-FSI is considerably reduced in superparallel
kinematics and can be practically negligible in specific kinematics.Comment: 16 pages, 9 figure
Modelling nucleon-nucleon scattering above 1 GeV
Motivated by the recent measurement of proton-proton spin-correlation
parameters up to 2.5 GeV laboratory energy, we investigate models for
nucleon-nucleon (NN) scattering above 1 GeV. Signatures for a gradual failure
of the traditional meson model with increasing energy can be clearly
identified. Since spin effects are large up to tens of GeV, perturbative QCD
cannot be invoked to fix the problems. We discuss various theoretical scenarios
and come to the conclusion that we do not have a clear phenomenological
understanding of the spin-dependence of the NN interaction above 1 GeV.Comment: 36 pages, 8 figure
Spectrum and decays of kaonic hydrogen
By using the non-relativistic effective Lagrangian approach to bound states,
a complete expression for the isospin-breaking corrections to the energy levels
and the decay widths of kaonic hydrogen is obtained up-to-and-including
O(alpha,m_d-m_u) in QCD. It is demonstrated that, although the leading-order
corrections at O(alpha^{1/2},(m_d-m_u)^{1/2}) emerging due to the unitarity
cusp, are huge, they can be expressed solely in terms of the KN S-wave
scattering lengths. Consequently, at leading order, it is possible to derive
parameter-free modified Deser-type relations, which can be used to extract the
scattering lengths from the hadronic atom data.Comment: 9 pages, 3 postscript figures, epj style. References added, minor
revisions in the text, results unchange
Strange particle production in proton-proton collisions at TeV with ALICE at the LHC
The production of mesons containing strange quarks (K, ) and both
singly and doubly strange baryons (, Anti-, and
+Anti-) are measured at central rapidity in pp collisions at
= 0.9 TeV with the ALICE experiment at the LHC. The results are
obtained from the analysis of about 250 k minimum bias events recorded in 2009.
Measurements of yields (dN/dy) and transverse momentum spectra at central
rapidities for inelastic pp collisions are presented. For mesons, we report
yields () of 0.184 0.002 stat. 0.006 syst. for K and
0.021 0.004 stat. 0.003 syst. for . For baryons, we find
= 0.048 0.001 stat. 0.004 syst. for , 0.047
0.002 stat. 0.005 syst. for Anti- and 0.0101 0.0020 stat.
0.0009 syst. for +Anti-. The results are also compared with
predictions for identified particle spectra from QCD-inspired models and
provide a baseline for comparisons with both future pp measurements at higher
energies and heavy-ion collisions.Comment: 33 pages, 21 captioned figures, 10 tables, authors from page 28,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/387
From Safety Net to Self Sufficiency: A CJC Proposal for a State Mixed Strategy Approach to Prepare TANF and Food Stamp Employment and Training Participants for Illinois' Skilled Workforce
Report details CJC's recommendation that Illinois Department of Human Services (IDHS) adopt a mixed strategy approach for Illinois' TANF and Food Stamp E&T programs. Features of this approach should include individualized assessment and employment planning; flexible combinations of education, training, life skills, and job search toward maximized job placement and career advancement; and necessary supportive services to address employment barriers and enhance family well-being. The Department must identify new local office performance measures and training which reorient services and service deliverers to success defined by skills attainment, wage placement, barrier reduction, and work support receipt.There is no better time than now to align IDHS TANF and Food Stamp work requirements along the continuum of workforce development system expectations so that participants have real access to employment services and real opportunities for family-sustaining employment. CJC is committed to working with the Department to imagine the implementation of a mixed strategy approach in Illinois and to achieve the best possible labor market results for Illinois' poor and working poor individuals and families, as well as Illinois' economy
Circular 78
Historically, sales of exotic meats have been limited only by supply. As supply has increased in recent years, national
and international exotic game markets have grown rapidly. In the United States, growth
has occurred primarily in the restaurant section, although over-the-counter sales
have also increased.
The Alaskan reindeer industry is exploring the potential of expanding its meat sales as well as antler sales. Meat production increased from 320,000 pounds in 1987 to 432,000 pounds in 1988. This production increase is reflected in a 27
percent increase in dollar value (Alaska Crop and Livestock Reporting Service, 1989). Under current management procedures, potential meat production has been estimated at 500,000 pounds (Pearson and Lewis, 1988). Any future market expansion
is likely to occur in urban Alaska and in areas outside the state (Jones, 1988)
Institutions, Information, and Trade Policy in Times of Crisis
The paper examines the role of international institutions in preventing the rise of protectionism in times of times of crisis. Economic crisis exacerbates uncertainty in the conduct of commercial relations and thus makes it more likely for countries to resort to "beggar-thy-neighbor" trade policies. The historical record of the Great Depression supports this argument, where global trade suffered a downward spiral as governments pursued protectionist trade policies as a response to domestic pressures. This paper argues that the current era of globalization is distinguishable from its earlier counterparts by the presence of an extensive network of international institutions, which serve as conveyors of information that help to mitigate the information problem that prevails in prisonerâs dilemma settings. Specifically, international institutions such as the WTO, preferential trade agreements (PTAs) and other international economic organizations increase the flow of information among countries. In doing so, they alleviate coordination problems as well as facilitate the detection of violations in commitments to maintaining a liberal trade regime. We suggest that this mechanism may explain why the current crisis is not replicating the pattern of the Great Depression. Moreover, we explore the combined effect of membership in international organization and political variables, the latter including democracy, veto players, partisanship of government, and government effectiveness. We test this argument using a newly-compiled dataset of trade policies during the current economic crisis and membership in international organizations. The paper finds strong support for the informational role of international institutions as a key factor preventing the rise of protectionism in times of crisis. Conversely, there is mixed evidence that the combining effect of international organizations and domestic political variables matters in explaining protectionism during this crisis
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