supported by

Collaborative Research Centre 16

Subnuclear Structure of Matter

B1. Photoproduction of mesons

F.Klein,H.Schmieden

The relative role of meson-baryon interactions and inter-quark dynamics is unsatisfactorily understood for several baryonic resonances. B.1 intends to provide new data, mainly for associated strangeness and vector meson photoproduction. The activities at the Crystal Barrel detector will be continued, but also will the enhanced performance at the newly built BGO-OD setup (
e.g. PID, tracking, magnetic spectroscopy) be exploited. Data taking shall begin still in 2012, measurements with linearly and circularly polarized beams are planned for end of 2013 onwards upon intermittent upgrades of the photon tagging system.

Publication

Published and accepted papers
A. Thiel et al. [CBELSA/TAPS Collaboration]
„Double-polarization observable G in neutral-pion photoproduction off the proton″,
[arXiv:1604.02922 [nucl-ex]].
A. Wilson et al. [CBELSA/TAPS Collaboration]
„Photoproduction of ω mesons off the proton″,
Phys. Lett. B 749 (2015) 407, [arXiv:1508.01483 [nucl-ex]].
H. Eberhardt et al. [CBELSA/TAPS Collaboration]
„Measurement of double polarisation asymmetries in ω-photoproduction″,
Phys. Lett. B 750 (2015) 453, [arXiv:1504.02221 [nucl-ex]].
J. Hartmann et al. [CBELSA/TAPS Collaboration]
„The polarization observables T , P , and H and their impact on γ p → p π0 multipoles″,
Phys. Lett. B 748 (2015) 212, [arXiv:1506.06226 [nucl-ex]].
A. Thiel et al. [CBELSA/TAPS Collaboration]
„Three-body nature of N* and Δ* resonances from sequential decay chains″,
Phys. Rev. Lett. 114 (2015) no.9, 091803, [arXiv:1501.02094 [nucl-ex]].
J. Hartmann et al. [CBELSA/TAPS Collaboration]
„The N(1520) 3/2- helicity amplitudes from an energy-independent multipole analysis based on new polarization data on photoproduction of neutral pions″,
Phys. Rev. Lett. 113 (2014) 062001, [arXiv:1407.2163 [nucl-ex]].
R. Ewald et al. [CBELSA/TAPS Collaboration]
„Measurement of polarisation observables in K0sΣ+ photoproduction off the proton″,
Phys. Lett. B 738 (2014) 268, [arXiv:1405.2729 [nucl-ex]].
M. Gottschall et al. [CBELSA/TAPS Collaboration]
„First measurement of the helicity asymmetry for γp → pπ0 in the resonance region″,
Phys. Rev. Lett. 112 (2014) 012003, [arXiv:1312.2187 [nucl-ex]].
A. Thiel et al. [CBELSA/TAPS Collaboration]
„Well-established nucleon reconances revisited by double-polarization measurements″,
Phys. Rev. Lett. 109(2012) 102001, [arXiv:1207.2686 [nucl-ex]].
R. Ewald et al. [CBELSA/TAPS Collaboration]
„Anomaly in the K0sΣ+ photoproduction cross section off the proton at the K* threshold″,
Phys. Lett. B 713 (2012) 180, [arXiv:1112.0811 [nucl-ex]].
V. Crede et al. [CBELSA/TAPS Collaboration]
„Photoproduction of Neutral Pions off Protons″,
Phys. Rev. C 84 (2011) 055203, [arXiv:1107.2151 [nucl-ex]].
I. Jaegle et al. [CBELSA/TAPS Collaboration]
„Quasi-free photoproduction of η-mesons off the deuteron″,
Eur. Phys. J. A 47 (2011) 89, [arXiv:1107.2046 [nucl-ex]].
M. Nanova, J. Weil, S. Friedrich, V. Metag, U. Mosel, M. Thiel et al. [CBELSA/TAPS Collaboration]
„Photoproduction of ω mesons on nuclei near the production threshold″,
Eur. Phys. J. A 47 (2011) 16, [arXiv:1008.4520 [nucl-ex]].
I. Jaegle et al. [CBELSA/TAPS Collaboration]
„Photoproduction of η'-mesons off the deuteron″,
Eur. Phys. J. A 47 (2011) 11, [arXiv:1012.1021 [nucl-ex]].
F. W. Wieland, et al.
„Study of the reaction γp → K+ Λ(1520) at photon energies up to 2.65 GeV″,
Eur. Phys. J. A 47 (2011) 47, [Erratum-ibid. A 47 (2011) 133].
I. Schulday, et al.
„Study of the reaction γp → K+ Σ±π at photon energies up to 2.6 GeV″,
Eur. Phys. J. A 47 (2011) 46, [arXiv:1011.0823 [nucl-ex]].
M. Nanova, V. Metag et al. [CBELSA/TAPS Collaboration]
„In-medium ω mass from the γ+Nb → π0γ+X reaction″,
Phys. Rev. C 82 (2010) 035209, [arXiv:1005.5694 [nucl-ex]].
E. Gutz et al. [CBELSA/TAPS Collaboration]
„Photoproduction of meson pairs: First measurement of the polarization observable Is,
Phys. Lett. B 687 (2010) 11, [arXiv:0912.2632 [nucl-ex]].
N. Sparks et al. [CBELSA/TAPS Collaboration]
„Measurement of the Beam Asymmetry Σ in the Forward Direction for γ p → pπ0 Photoproduction″,
Phys. Rev. C 81 (2010) 065210, [arXiv:1003.1346 [nucl-ex]].
V. Crede et al. [CBELSA/TAPS Collaboration]
„Photoproduction of η and η' mesons off protons″,
Phys. Rev. C 80 (2009) 055202, [arXiv:0909.1248 [nucl-ex]].
D. Elsner et al. [CBELSA/TAPS Collaboration]
„Linearly polarised photon beams at ELSA and measurement of the beam asymmetry in π0-photoproduction off the proton″,
Eur. Phys. J. A 39 (2009) 373.
A. V. Sarantsev, A. V. Anisovich, V. A. Nikonov and H. Schmieden
„Polarization degrees of freedom in near-threshold photoproduction of ω mesons in the π0γ decay channel″,
Eur. Phys. J. A 39 (2009) 61.
Frank Klein et al. [CBELSA/TAPS Collaboration]
„Beam asymmetry in near threshold ω photoproduction off the proton″,
Phys. Rev. D 78 (2008) 117101.
I. Horn et al. [CB-ELSA Collaboration]
„Evidence for a Parity Doublet Δ(1920)P33 and Δ(1940)D33 from γp → pπ0 η″,
Phys. Rev. Lett. 101 (2008) 202002, [arXiv:0711.1138 [nucl-ex]].
I. Horn et al. [CB-ELSA Collaboration]
„Study of the reaction γ p → p π0 η″,
Eur. Phys. J. A 38 (2008) 173, [arXiv:0806.4251 [nucl-ex]].
T. Mertens et al. [CBELSA/TAPS Collaboration]
„Photoproduction of η-mesons off nuclei for Eγ ≤ 2.2 GeV″,
Eur. Phys. J. A 38 (2008) 195, [arXiv:0810.2678 [nucl-ex]].
R. Castelijns et al. [CBELSA/TAPS Collaboration]
„Nucleon resonance decay by the K0Σ+ channel″,
Eur. Phys. J. A 35 (2008) 39.
E. Gutz et al. [CBELSA/TAPS Collaboration]
„Measurement of the beam asymmetry Σ in π0η production off the proton with the CBELSA/TAPS experiment″,
Eur. Phys. J. A 35 (2008) 291.
M. Nanova et al. [CBELSA/TAPS Collaboration]
„K0 π0 Σ+ and K*0 Σ+ photoproduction off the proton″,
Eur. Phys. J. A 35 (2008) 333, [arXiv:0803.2146 [nucl-ex]].
M. Kotulla, D. Trnka, P. Mühlich et al. [CBELSA/TAPS Collaboration]
„Modification of the ω-Meson Lifetime in Nuclear Medium″,
Phys Rev. Lett. 100 (2008) 192302, [arXiv:0802.0989 [nucl-ex]].
I. Jaegle et al. [CBELSA/TAPS Collaboration]
„Quasi-free photoproduction of η-mesons of the neutron″,
Phys. Rev. Lett. 100 (2008) 252002, [arXiv:0804.4841 [nucl-ex]].
J. Junkersfeld et al. [CB-ELSA Collaboration]
„Photoproduction of π0ω off protons for Eγ ≤ 3 GeV″,
Eur. Phys. J. A 31 (2007) 365, [arXiv:0704.0710 [nucl-ex]].
U. Thoma, M. Fuchs et al. [CB-ELSA Collaboration]
„N* and Δ* decays into Nπ0π0,
Phys. Lett. B 659 (2008) 87-93, [arXiv:0707.3592 [hep-ph]].
A. V. Anisovich, V. Kleber, E. Klempt, V. A. Nikonov, A. V. Sarantsev and U. Thoma
„Baryon resonances and polarization transfer in hyperon photoproduction″,
Eur. Phys. J. A 34 (2007) 243.
D. Elsner et al. [CBELSA/TAPS Collaboration]
„Measurement of the beam asymmetry in η-photoproduction off the proton″,
Eur. Phys. J. A 33 (2007) 147.
H. Schmieden
„Photo- and electro-excitation of the Δ-resonance″,
Eur. Phys. J. A 28, s01, 91 (2006).
O. Bartholomy, V. Crede, H. van Pee et al. [CB-ELSA Collaboration]
„Neutral pion photoproduction off protons in the energy range 0.3 GeV < Eγ < 3 GeV″,
Phys. Rev. Lett. 94 (2005) 012003, [arXiv:hep-ex/0407022].
V. Crede, O. Bartholomy et al. [CB-ELSA Collaboration]
„Photoproduction of η mesons off protons for 0.75 GeV < Eγ < 3 GeV″,
Phys. Rev. Lett. 94 (2005) 012004, [arXiv:hep-ex/0311045].