556 research outputs found
Amplitude analysis of reactions pi(-)p->etapi(-)p and pi(-)p->etapi(0)n on polarized target and the exotic 1-+ meson
Recently several experimental groups analysed data on and reactions with exotic -wave and
found a conflicting evidence for an exotic meson . High
statistics data on these reactions are presently analysed by BNL E852
Collaboration. All these analyses are based on the crucial assumption that the
production amplitudes do not depend on nucleon spin. This assumption is in
sharp conflict with the results of measurements of ,
and on polarized targets at
CERN which find a strong dependence of production amplitudes on nucleon spin.
To ascertain the existence of exotic meson , it is necessary to
perform a model-independent amplitude analysis of reactions and . We demonstrate that measurements of
these reactions on transversely polarized targets enable the required model
independent amplitude analysis without the assumption that production
amplitudes are independent on nucleon spin. We suggest that high statistics
measurements of reactions and be made on polarized targets at BNL and at Protvino IHEP, and that
model-independent amplitude analyses of this polarized data be performed to
advance hadron spectroscopy on the level of spin dependent production
amplitudes.Comment: 23 page
The preparation, identification and properties of chlorophyll derivatives
In the investigation of 10-hydroxy chlorophylls a and b novel techniques included modification of chromatography and the use of fully-deuterated compounds isolated from fully-deuterated autotropic algae to determine the molecular structure of the chlorophylls
Nitrogen isotope abundance measurements
The abundance of the nitrogen isotopes in several sources of nitrogen have been determined. In atmospheric nitrogen the absolute ratio, N14/N15, is 272.0 ± 0.3. Small variations were observed for various sources of compressed gas but the isotopic composition of the nitrogen isotopes of the atmosphere was constant, to 1 part in 7000, in samples collected at different geographical sites and altitudes above these sites
Unitarity and Interfering Resonances in pipi Scattering and in Pion Production piN->pipiN
Additivity of Breit-Wigner phases has been proposed to describe interfering
resonances in partial waves in scattering. This assumption leads to an
expression for partial wave amplitudes that involves products of Breit-Wigner
amplitudes. We show that this expression is equivalent to a coherent sum of
Breit-Wigner amplitudes with specific complex coefficients which depend on the
resonance parameters of all contributing resonances. We use analyticity of
partial wave amplitudes to show that they must have the form of a
coherent sum of Breit-Wigner amplitudes with complex coefficients and a complex
coherent background. The assumption of additivity of Breit-Wigner phases
restricts the partial waves to analytical functions with very specific form of
residues of Breit-Wigner poles. We argue that the general form provided by the
analyticity is more appropriate in fits to data to determine resonance
parameters. The partial wave unitarity can be imposed using the modern methods
of constrained optimization. We discuss unitarity and the production amplitudes
in and use analyticity in the dipion mass variable to
justify the common practice of writing the production amplitudes as a coherent
sum of Breit-Wigner amplitudes with free complex coefficients and a complex
coherent background in fits to mass spectra with interfering resonances.Comment: 31 page
Relevance of nucleon spin in amplitude analysis of reactions pi(-)p->pi(0)pi(0)n and pi(-)p->eta eta n
The measurements of reactions and on polarized targets at CERN found a strong dependence of pion
production amplitudes on nucleon spin. Analyses of recent measurements of
reaction on unpolarized targets by GAMS
Collaboration at 38 GeV/c and BNL E852 Collaboration at 18 GeV/c use the
assumption that pion production amplitudes do not depend on nucleon spin, in
conflict with the CERN results on polarized targets. We show that measurements
of and on unpolarized
targets can be analysed in a model independent way in terms of 4 partial-wave
intensities and 3 independent interference phases in the mass region where -
and -wave dominate. We also describe model-independent amplitude analysis of
reaction measured on polarized target, both in the
absence and in the presence of -wave amplitudes. We suggest that high
statistics measurements of reactions and be made on polarized targets at Protvino IHEP and at BNL, and
that model-independent amplitude analyses of this polarized data be performed
to advance hadron spectroscopy on the level of spin dependent production
amplitudes.Comment: 54 page
STRUCTURE OF METHYLPHEOPHORBIDE-RCI
he methanolic extract of the cyanobacterium (blue-green alga) Spirulina geitleri has been treated with methanolic acid to convert all chlorophyllous pigments to their methylpheophorbides. Fractionation of the latter from methylpheophorbide a by thin layer chromatography and high pressure liquid chromatography yielded methylpheophorbide-RCI. Its structure has been determined as 132S-hydroxy-20-chloro-methylpheophorbide a by 1H-nuclear magnetic resonance, absorption and circular dichroism spectroscopy, mass spectrometry and by partial synthesis from chlorophyll a. The pigment is isolated from Spirulina geitleri irrespective of the use or omission of chlorinated substances during the isolation procedure
Mass and width of sigma(750) scalar meson from measurements of piN->pi(-)pi(+)N on polarized targets
The measurements of reactions at 17.2
GeV/c and at 5.98 and 11.85 GeV/c made at
CERN with polarized targets provide a model-independent and
solution-independent evidence for a narrow scalar state sigma(750). The
original chi^2 minimization method and the recent Monte Carlo method for
amplitude analysis of data at 17.2 GeV/c are in excellent agreement. Both
methods find that the mass distribution of the measured amplitude with recoil transversity ``up'' resonates near 750 MeV while the
amplitude with recoil transversity ``down'' is large and
nonresonating. The amplitude contributes as a strong background
to S-wave intensity I_S = (|S|^2 + |\overline S |^2)\Sigma\sigmaI_S|\overline S |^2\Sigmatm_\sigma = 753 \pm 19\Gamma_\sigma = 108 \pm 53\sigma(750)\sigma(750)\gamma\gamma \to \pi\pi\pi\pi$ phase shifts .Comment: 77 page
scattering S wave from the data on the reaction
The results of the recent experiments on the reaction
performed at KEK, BNL, IHEP, and CERN are analyzed in detail. For the I=0
S wave phase shift and inelasticity a new set
of data is obtained. Difficulties emerging when using the physical solutions
for the S and D wave amplitudes extracted with the partial wave
analyses are discussed. Attention is drawn to the fact that, for the
invariant mass, m, above 1 GeV, the other solutions, in principle,
are found to be more preferred. For clarifying the situation and further
studying the resonance thorough experimental investigations of the
reaction in the m region near the threshold
are required.Comment: 17 pages, 5 figure
Vector and Scalar Meson Resonances in Decays
Corrections to induced by vector and scalar meson
exchange are investigated within chiral perturbation theory.Comment: 15pages, Latex-file, TUM-T31-41/9
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