First Measurements of the Double-Polarization Observables 
F
, 
P
, and 
H
 in 
ω
 Photoproduction off Transversely Polarized Protons in the 
N*
 Resonance Region

Polarization observables are vital for disentangling overlapping resonances in the baryon spectrum. Extensive data have been collected at Jefferson Lab in Hall B with circularly and linearly polarized tagged photon beam incident on longitudinally polarized protons provided by the Frozen Spin Target (FROST). The focus of the described work is on η photoproduction, which acts as an "isospin filter", isolating the N*(I = 1/2) resonances. Preliminary results for the double-polarization observables E and G are presented. There are currently no data on these in the world database for η photoproduction.

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POLARIZATION OBSERVABLES OF THE γd→πNN REACTION IN THE Δ(1232)-RESONANCE REGION

International Journal of Modern Physics E ◽

10.1142/s0218301304002612 ◽

2004 ◽

Vol 13 (06) ◽

pp. 1191-1207 ◽

Cited By ~ 7

Author(s):

EED M. DARWISH

Keyword(s):

Perturbation Theory ◽

Resonance Region ◽

Photon Beam ◽

Deuteron Target ◽

Model Based ◽

Nonrelativistic Model ◽

Double Polarization ◽

Polarization Observables ◽

Photon Asymmetry ◽

First Time

Polarization observables of the three charge states of the pion for the γd→π NN reaction with polarized photon beam and/or oriented deuteron target are evaluated over the whole Δ(1232)-resonance region adopting a nonrelativistic model based on time-ordered perturbation theory. Results for the π-meson spectra, linear photon asymmetry, vector and tensor target asymmetries are presented. Particular attention is given, for the first time, to double polarization asymmetries for which we present results for [Formula: see text] and [Formula: see text]. We find that all other double polarization asymmetries of photon and deuteron targets vanish.

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POLARIZATION OBSERVABLES FOR K+Λ AND K+Σ0 PHOTOPRODUCTION FROM POLARIZED PROTONS

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194514600982 ◽

2014 ◽

Vol 26 ◽

pp. 1460098

Author(s):

◽

NATALIE K. WALFORD ◽

FRANZ J. KLEIN

Keyword(s):

Excited States ◽

Final States ◽

Polarization Data ◽

Polarized Protons ◽

Model Predictions ◽

Double Polarization ◽

Model Independent ◽

Polarization Observables ◽

Large Effort ◽

Polarized Photons

The search for undiscovered excited states of the nucleon continues to be a focus of experiments at Jefferson Lab. Recent LQCD calculations have confirmed long-standing quark-model predictions of many more states than have so far been identified.1 A large effort for the N* program has been launched using the CLAS detector to provide the database that will allow nearly model-independent partial wave analyses to be carried out in the search for such states. Polarization observables play a crucial role in this effort, as they are essential in disentangling overlapping resonant and non-resonant amplitudes. In 2010, double-polarization data were taken at JLab using circularly polarized photons incident on a transversely polarized frozen-spin butanol target.2 Our current analysis yields preliminary data of the T and F asymmetries of the K+Λ and K+Σ0 final states, which are compared to predictions of recent multipole analyses. This work is the first of its kind and will significantly broaden the world database for these reactions.

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Polarization Observables in Double-Charged-Pion Photo-Production with Circularly-Polarized Photons Off Transversely-Polarized Protons

Few-Body Systems ◽

10.1007/s00601-018-1445-0 ◽

2018 ◽

Vol 59 (6) ◽

Author(s):

L. A. Net ◽

◽

S. Strauch

Keyword(s):

Charged Pion ◽

Circularly Polarized ◽

Polarized Protons ◽

Polarization Observables ◽

Polarized Photons ◽

Photo Production

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General helicity formalism for two-hadron production in e+e− annihilation within a TMD approach

Journal of High Energy Physics ◽

10.1007/jhep10(2021)078 ◽

2021 ◽

Vol 2021 (10) ◽

Author(s):

Umberto D’Alesio ◽

Francesco Murgia ◽

Marco Zaccheddu

Keyword(s):

Transverse Momentum ◽

Hadron Production ◽

Probabilistic Interpretation ◽

Leading Order ◽

Transverse Momentum Dependent ◽

Factorization Scheme ◽

Helicity Formalism ◽

Double Polarization ◽

Fragmentation Functions ◽

Polarization Observables

Abstract We present the complete leading-order results for the azimuthal dependences and polarization observables in e+e−→ h1h2 + X processes, where the two hadrons are produced almost back-to-back, within a transverse momentum dependent (TMD) factorization scheme. We consider spinless (or unpolarized) and spin-1/2 hadron production and give the full set of the corresponding quark and gluon TMD fragmentation functions (TMD-FFs). By adopting the helicity formalism, which allows for a more direct probabilistic interpretation, single- and double-polarization cases are discussed in detail. Simplified expressions, useful for phenomenological analyses, are obtained by assuming a factorized Gaussian-like dependence on intrinsic transverse momenta for the TMD-FFs.

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Recent results from the CBELSA/TAPS experiment at ELSA

EPJ Web of Conferences ◽

10.1051/epjconf/202024101001 ◽

2020 ◽

Vol 241 ◽

pp. 01001

Author(s):

Farah Afzal

Keyword(s):

Final States ◽

Excitation Spectra ◽

Unpolarized Cross Section ◽

Polarized Target ◽

Double Polarization ◽

Perturbative Regime ◽

Measured Polarization ◽

Polarization Observables ◽

The Impact ◽

Photoproduction Reactions

In order to gain a better understanding of the dynamics inside the nucleon and of the non-perturbative regime of QCD, the nucleon excitation spectra and the properties of nucleon resonances are investigated. An essential experimental tool to achieve this goal is the study of different photoproduction reactions. Partial wave analyses are performed in order to obtain information about the contributing resonances. A complete experiment is needed to extract the underlying amplitudes unambiguously, which requires the measurement of carefully chosen single and double polarization observables in addition to the unpolarized cross section. The CBELSA/TAPS experiment in Bonn offers the possibility to measure several polarization observables using a linearly or circularly polarized photon beam and with a longitudinally or transversely polarized target. This contribution gives an overview of recently measured polarization observables in different final states. The impact of the new data is discussed.

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