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 $\pi^- p \to \eta \pi^- p$ and $\pi^- p \to \eta \pi^0 n$ reactions with exotic $1^{-+}$ $P$-wave and found a conflicting evidence for an exotic meson $I=1 1^{-+} (1405)$. 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 $\pi^- p \to \pi^- \pi^+ n$, $\pi^+ n \to \pi^+ \pi^- p$ and $K^+ n \to K^+ \pi^- p$ on polarized targets at CERN which find a strong dependence of production amplitudes on nucleon spin. To ascertain the existence of exotic meson $1^{-+} (1405)$, it is necessary to perform a model-independent amplitude analysis of reactions $\pi^- p \to \eta \pi^- p$ and $\pi^- p \to \eta\pi^0 n$. 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 $\pi^- p \to \eta\pi^- p$ and $\pi^- p \to\eta\pi^0 n$ 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

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 $\pi\pi$ 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 $\pi\pi$ 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 $\pi N\to\pi\pi N$ 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 $\pi^- p \to \pi^- \pi^+ n$ and $\pi^+ n \to \pi^+ \pi^- p$ on polarized targets at CERN found a strong dependence of pion production amplitudes on nucleon spin. Analyses of recent measurements of $\pi^- p \to \pi^0\pi^0 n$ 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 $\pi^- p \to \pi^0\pi^0 n$ and $\pi^- p \to \eta\eta n$ 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 $S$- and $D$-wave dominate. We also describe model-independent amplitude analysis of $\pi^- p \to \pi^0\pi^0 n$ reaction measured on polarized target, both in the absence and in the presence of $G$-wave amplitudes. We suggest that high statistics measurements of reactions $\pi^- p \to \pi^0 \pi^0 n$ and $\pi^- p \to \eta\eta n$ 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

Hyperinsulinemia in African-American Adolescents Compared With Their American White Peers Despite Similar Insulin Sensitivity: A reflection of upregulated β-cell function?

OBJECTIVE—African-American (AA) children are hyperinsulinemic and insulin resistant compared with American white (AW) children. Previously, we demonstrated that insulin secretion relative to insulin sensitivity was ∼75% higher in AA compared with AW children, suggesting that hyperinsulinemia in AA children is not merely a compensatory response to lower insulin sensitivity. The aim of the present investigation was to assess whether glucose-stimulated insulin response is higher in AA versus AW adolescents who have comparable in vivo insulin sensitivity

Correction of RT–qPCR data for genomic DNA-derived signals with ValidPrime

Genomic DNA (gDNA) contamination is an inherent problem during RNA purification that can lead to non-specific amplification and aberrant results in reverse transcription quantitative PCR (RT—qPCR). Currently, there is no alternative to RT(−) controls to evaluate the impact of the gDNA background on RT–PCR data. We propose a novel method (ValidPrime) that is more accurate than traditional RT(−) controls to test qPCR assays with respect to their sensitivity toward gDNA. ValidPrime measures the gDNA contribution using an optimized gDNA-specific ValidPrime assay (VPA) and gDNA reference sample(s). The VPA, targeting a non-transcribed locus, is used to measure the gDNA contents in RT(+) samples and the gDNA reference is used to normalize for GOI-specific differences in gDNA sensitivity. We demonstrate that the RNA-derived component of the signal can be accurately estimated and deduced from the total signal. ValidPrime corrects with high precision for both exogenous (spiked) and endogenous gDNA, contributing ∼60% of the total signal, whereas substantially reducing the number of required qPCR control reactions. In conclusion, ValidPrime offers a cost-efficient alternative to RT(−) controls and accurately corrects for signals derived from gDNA in RT–qPCR

Mass and width of sigma(750) scalar meson from measurements of piN->pi(-)pi(+)N on polarized targets

The measurements of reactions $\pi^- p_\uparrow \to \pi^- \pi^+ n$ at 17.2 GeV/c and $\pi^+ n_\uparrow \to \pi^+ \pi^- p$ 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 $|\overline S |^2\Sigma$ with recoil transversity ``up'' resonates near 750 MeV while the amplitude $|S|^2\Sigma$ with recoil transversity ``down'' is large and nonresonating. The amplitude $|S|^2\Sigma$ contributes as a strong background to S-wave intensity I_S = (|S|^2 + |\overline S |^2)\Sigma$and distorts the determinations of$\sigma$resonance parameters from$I_S$. To avoid this problem we perform a series of Breit-Wigner fits directly to the measured distribution$|\overline S |^2\Sigma$. The inclusion of various backgrounds causes the width of sigma(750) to become very narrow. Our best fit with$t$-averaged coherent background yields$m_\sigma = 753 \pm 19$MeV and$\Gamma_\sigma = 108 \pm 53$MeV. These values are in excellent agreement with Ellis-Lanik theorem for the width of scalar gluonium. The gluonium interpretation of$\sigma(750)$is also supported by the absence of$\sigma(750)$in reactions$\gamma\gamma \to \pi\pi$. We also show how data on polarized target invalidate essential assumptions of past determinations of$\pi\pi$ phase shifts .Comment: 77 page

Vector and Scalar Meson Resonances in K→πππK\rightarrow\pi\pi\pi Decays

Corrections to $K\rightarrow\pi\pi\pi$ induced by vector and scalar meson exchange are investigated within chiral perturbation theory.Comment: 15pages, Latex-file, TUM-T31-41/9