The target asymmetry
T
, recoil asymmetry
P
, and beam-target double polarization observable
H
were determined in exclusive
π
0
and
η
photoproduction off quasi-free protons and, for the first time, ...off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the
γ
p
→
π
0
p
and
γ
p
→
η
p
reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the
η
n
system at
W
=
1.68
GeV
. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the
S
11
(
1535
)
and
S
11
(
1650
)
resonances within the
S
11
-partial wave.
BGO-OD is a new meson photoproduction experiment at the ELSA facility of Bonn University. It aims at the investigation of non strange and strange baryon excitations, and is especially designed to be ...able to detect weekly bound meson-baryon type structures. The setup for the BGO-OD experiment is presented, the characteristics of the photon beam and the detector performances are shown and the initial experimental program is discussed.
The rat-tail syndrome (RTS) is a bovine congenital, inherited hypotrichosis characterized by various degrees of sparse, curled malformed hair and by missing hair at the animal's tail switch. The ...defect in hair conformation is restricted to pigmented sections of the pelage and has been observed in crosses between black cattle breeds (e.g., Angus and Holstein) and some European breeds with the specific feature of coat color dilution (e.g., Simmental, Charolais and Hereford). Due to partially controversial results in the literature, the full causal genetic background of RTS is still under debate. Thus, the aim of this study was to monitor the genetic architecture of RTS and to map the locus (or loci) epistatically interacting for RTS. Taking advantage of a resource cross population from German Holstein and Charolais cattle breeds, which was segregating for RTS, we proved that epistatic effects of at least three independent genetic loci are required for the expression of the "rat tail" phenotype. We found that in our population, RTS is exclusively expressed on a eumelanic background with the dominant ED allele at the Extension locus (MC1R gene) located on BTA18. In addition, only individuals heterozygous for the Dilution locus on BTA5 (c.64G > A at the PMEL or SILV gene) were classified as rat-tail phenotype. However, the results of our segregation analysis prove that a two locus model including the Extension and the Dilution locus is obligatory but not sufficient to fully explain the rat-tail phenotype. Our results provide evidence that epistatic interaction with at least a third independent locus is required for its expression. Applying linkage and whole genome association analyses with different models and in different pedigrees, the third locus essential for the expression of the rat-tail phenotype was mapped consistently to the chromosomal region 14-22 Mb on BTA5, obviously affecting hair structure as well as hair pigmentation. We clearly demonstrated that this third locus is distinct from the Dilution locus represented by the PMEL gene. Finally, the results of our study exclude several loci repotted to be associated or underlying hair conformation or pigmentation traits as causal mutation for RTS and also promising functional and positional candidate genes associated with hypotrichosis in humans. RTS with its three locus interaction is a prime example for epistatic interaction of several independent loci required for the expression of a distinct phenotype.
Abstract
The target asymmetry
T
, recoil asymmetry
P
, and beam-target double polarization observable
H
were determined in exclusive
$$\pi ^0$$
π
0
and
$$\eta $$
η
photoproduction off quasi-free ...protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the
$$\gamma p \rightarrow \pi ^0 p$$
γ
p
→
π
0
p
and
$$\gamma p \rightarrow \eta p$$
γ
p
→
η
p
reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the
$$\eta n$$
η
n
system at
$$W = 1.68\ \textrm{GeV}$$
W
=
1.68
GeV
. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the
$$S_{11}(1535)$$
S
11
(
1535
)
and
$$S_{11}(1650)$$
S
11
(
1650
)
resonances within the
$$S_{11}$$
S
11
-partial wave.
The target asymmetry
T
, recoil asymmetry
P
, and beam-target double polarization observable
H
were determined in exclusive
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
...\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\pi ^0$$\end{document}
π
0
and
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\eta $$\end{document}
η
photoproduction off quasi-free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\gamma p \rightarrow \pi ^0 p$$\end{document}
γ
p
→
π
0
p
and
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\gamma p \rightarrow \eta p$$\end{document}
γ
p
→
η
p
reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\eta n$$\end{document}
η
n
system at
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$W = 1.68\ \textrm{GeV}$$\end{document}
W
=
1.68
GeV
. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$S_{11}(1535)$$\end{document}
S
11
(
1535
)
and
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$S_{11}(1650)$$\end{document}
S
11
(
1650
)
resonances within the
\documentclass12pt{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$S_{11}$$\end{document}
S
11
-partial wave.
Eu
Na
Si
Te
, monoclinic, C12/m1 (no. 12), a = 7.648(1) Å, b = 13.223(2) Å, c = 8.439(1) Å, β = 107.667(3)°, V = 813.1 Å
, Z = 1, R
(F) = 0.029, wR
(F
) = 0.059, T = 298 K.
Ge
LaNa
Se
, monoclinic, C12/m1 (no. 12), a = 7.974(1) Å, b = 12.337(2) Å, c = 7.114(1) Å, β = 107.101(3)°, V = 669.0 Å
, Z = 1, R
(F) = 0.027, wR
(F
) = 0.053, T = 173 K.
KS
SiYb, monoclinic, P12
1 (no. 4), a = 6.316(5) Å, b = 6.557(5) Å, c = 8.571(7) Å, β = 108.09(1)°, V = 337.4 Å
, Z = 2, R
(F) = 0.025, wR
(F
) = 0.059, T = 298 K.
PDF
