1,284 research outputs found
Complete Sets of Polarization Observables in Electromagnetic Deuteron Break-up
For deuteron photo- and electrodisintegration the selection of complete sets
of polarization observables is discussed in detail by applying a recently
developed new criterion for the check of completeness of a chosen set of
observables. The question of ambiguities and their resolution by considering
additional observables is discussed for a numerical example, for which the role
of experimental uncertainties is also investigated. Furthermore, by inversion
of the expressions of the observables as hermitean forms in the -matrix
elements a bilinear term of the form can be given as a complex
linear form in the observables from which an explicit solution for in
terms of observables can be obtained. These can also be used to select sets of
observables for the explicit representation of the -matrix.Comment: 37 pages revte
General Multipole Expansion of Polarization Observables in Deuteron Electrodisintegration
Formal expressions are derived for the multipole expansion of the structure
functions of a general polarization observable of exclusive
electrodisintegration of the deuteron using a longitudinally polarized beam
and/or an oriented target. This allows one to exhibit explicitly the angular
dependence of the structure functions by expanding them in terms of the small
rotation matrices , whose coefficients are given in terms of
the electromagnetic multipole matrix elements. Furthermore, explicit
expressions for the coefficients of the angular distributions of the
differential cross section including multipoles up to are listed in
tabular form.Comment: 23 pages revtex including one figure, accepted for Eur.Phys. J.
Improved (e,e') response functions at intermediate momentum transfers: the 3He case
A possibility of extending the applicability range of non-relativistic
calculations of electronuclear response functions in the quasielasic peak
region is studied. We show that adopting a particular model for determining the
kinematical inputs of the non-relativistic calculations can extend this range
considerably, almost eliminating the reference frame dependence of the results.
We also show that there exists one reference frame, where essentially the same
result can be obtained with no need of adopting the particular kinematical
model. The calculation is carried out with the Argonne V18 potential and the
Urbana IX three-nucleon interaction. A comparison of these improved
calculations with experimental data shows a very good agreement for the
quasielastic peak positions at 600, 700 MeV/c and for the peak heights
at the two lower --values, while for the peak height at MeV/c one
finds differences of about 20%.Comment: 10 pages, 4 figure
Interacting photon-baryon fluid, warm dark matter and the first acoustic peak
The Reduced Relativistic Gas (RRG) model was introduced by A. Sakharov in
1965 for deriving the cosmic microwave background (CMB) spectrum. It was
recently reinvented by some of us to achieve an interpolation between the
radiation and dust epochs in the evolution of the Universe. This model
circumvents the complicated structure of the Boltzmann-Einstein system of
equations and admits a transparent description of warm-dark-matter effects. It
is extended here to include, on a phenomenological basis, an out-of-equilibrium
interaction between radiation and baryons which is supposed to account for
relevant aspects of pre-recombination physics in a simplified manner.
Furthermore, we use the tight-coupling approximation to explore the influence
of both this interaction and of the RRG warmness parameter on the anisotropy
spectrum of the CMB. The predictions of the model are very similar to those of
the {\Lambda}CDM model if both the interaction and the dark-matter warmness
parameters are of the order of or smaller. As far as the warmness
parameter is concerned, this is in good agreement with previous estimations on
the basis of results from structure formation.Comment: 10 pages and 4 figure
The Lorentz integral transform (LIT) method
The LIT approach is reviewed both for inclusive and exclusive reactions. It
is shown that the method reduces a continuum state problem to a
bound-state-like problem, which then can be solved with typical bound-state
techniques. The LIT approach opens up the possibility to perform ab initio
calculations of reactions also for those particle systems which presently are
out of reach in conventional approaches with explicit calculations of many-body
continuum wave functions. Various LIT applications are discussed ranging from
particle systems with two nucleons up to particle systems with seven nucleons.Comment: Lectures delivered at the 4th DAE-BRNS Workshop on Hadron Physics,
AMU, Aligarh, India, Feb. 18-23, 2008; 23 pages, 16 figure
On Complete Sets of Polarization Observables
A new criterion is developed which provides a check as to whether a chosen
set of polarization observables is complete with respect to the determination
of all independent -matrix elements of a reaction of the type . As an illustrative example, this criterion is applied to the
longitudinal observables of deuteron electrodisintegration.Comment: 8 pages revtex, final version, accepted for Nucl. Phys.
Development and function of murine B220+CD11c+NK1.1+ cells identify them as a subset of NK cells
Lymphoid organs contain a B220+CD11c+NK1.1+ cell population that was recently characterized as a novel dendritic cell (DC) subset that functionally overlaps with natural killer (NK) cells and plasmacytoid DCs (PDCs). Using Siglec-H and NK1.1 markers, we unambiguously dissected B220+CD11c+ cells and found that PDCs are the only professional interferon (IFN)-α–producing cells within this heterogeneous population. In contrast, B220+CD11c+NK1.1+ cells are a discrete NK cell subset capable of producing higher levels of IFN-γ than conventional NK cells. Unlike DCs, only a minute fraction of B220+CD11c+NK1.1+ cells in the spleen expressed major histocompatibility complex class II ex vivo or after stimulation with CpG. Consistent with being a NK cell subset, B220+CD11c+NK1.1+ cells depended primarily on interleukin 15 and common cytokine receptor γ chain signaling for their development. In terms of function, expression of distinctive cell surface receptors, and location in lymphoid organs, NK1.1+B220+CD11c+ appear to be the murine equivalent of human CD56bright NK cells
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