scholarly journals Measurement of the double polarization observables E and G at the Crystal Ball experiment at MAMI

2016 ◽  
Author(s):  
Farah Afzal
Keyword(s):  
Crystal Ball ◽  
Double Polarization ◽  
Polarization Observables

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

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.

scholarly journals Recent results from the CBELSA/TAPS experiment at ELSA

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.

scholarly journals DETERMINATION OF E AND G OBSERVABLES IN η PHOTOPRODUCTION ON THE CLAS FROZEN SPIN TARGET (FROST)

2014 ◽  
Vol 26 ◽  
pp. 1460115
Author(s):  
◽  
IGOR SENDEROVICH ◽  
B. T. MORRISON ◽  
M. DUGGER ◽  
B. RITCHIE ◽  
...  
Keyword(s):  
Baryon Spectrum ◽  
Preliminary Results ◽  
Extensive Data ◽  
Polarized Protons ◽  
The World ◽  
Double Polarization ◽  
Linearly Polarized ◽  
Beam Incident ◽  
Polarization Observables

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.

HADRON PHYSICS WITH THE CRYSTAL BALL AT MAMI

2009 ◽  
Vol 24 (02n03) ◽  
pp. 287-294
Author(s):  
◽  
ALEKSANDR STAROSTIN
Keyword(s):  
Detection System ◽  
Maximum Energy ◽  
Particle Identification ◽  
Current Status ◽  
Meson Photoproduction ◽  
Crystal Ball ◽  
Physics Program ◽  
Wide Range ◽  
Double Polarization ◽  
Linearly Polarized

The physics program of the Crystal Ball spectrometer at MAMI-C began in early 2007. Experiments utilize the upgraded electron accelerator that provides high intensity beams of circularly and linearly polarized real photons with maximum energy of 1.5 GeV. The highly segmented nearly 4π acceptance detection system consists of the Crystal Ball, particle identification detector and versatile endcap TAPS. A wide range of physics topics is under study including the production and decay of η, ω, and η' mesons, the investigation of coherent meson photoproduction on nuclei, measurements of polarization and double polarization observables in meson photoproduction on proton and neutron. The current status of the experiment and some preliminary results are reported.

scholarly journals Measurement of polarization observables in neutral double pion photoproduction off the proton with the CBELSA/TAPS experiment

2020 ◽  
Vol 241 ◽  
pp. 01016
Author(s):  
Tobias Seifen
Keyword(s):  
Internal Structure ◽  
Branching Ratios ◽  
Pion Photoproduction ◽  
Double Polarization ◽  
Double Pion ◽  
Linearly Polarized ◽  
Polarization Observables ◽  
Polarized Photons

Data on the reaction γp → pπ0π0 were taken with the CBELSA/TAPS experiment at ELSA where linearly polarized photons impinged on a transversely polarized butanol target. Target asymmetries and double polarization observables were extracted and entered the BnGa-PWA. Systematic differences in the branching ratios of N* and Δ* resonances hint at the internal structure of these states

DOUBLE-POLARIZATION OBSERVABLES IN PION-PHOTOPRODUCTION FROM POLARIZED HD AT LEGS

NSTAR 2005 ◽  
2006 ◽  
Author(s):  
A. M. Sandorfi ◽  
K. Ardashev ◽  
C. Bade ◽  
M. Blecher ◽  
A. Caracappa ◽  
...  
Keyword(s):  
Pion Photoproduction ◽  
Double Polarization ◽  
Polarization Observables
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