[G12] Review of analysis procedure

[Carlos Salgado]

Hi!

Nice results. Have you look of some photon signal in the calorimeter in your eta sample? Do you have any reconstructed eta?  also Do you
contemplate to do kinematic fits?
-Carlos

On Jul 16, 2015, at 10:00 AM, Cathrina Sowa wrote:

> Dear colleagues,
> 
> I would like to present preliminary results of the analysis (gamma p -> p pi+ pi- (eta))
> I am working on at a parallel session at the upcoming EUNPC 2015 conference in Groningen.
> 
> The analysis was presented at the CLAS collaboration meeting in June at the
> the Hadron Spectroscopy session [1]. All concerns and comments raised during the
> discussion after the talk have been considered. The energy dependent scaling factor for
> the differential cross section for example is now no longer needed.
> 
> In order to follow the required procedure, Johann and Mario advised me to
> discuss the updated analysis with the g12 run group. Below I prepared a summary of the
> data selection and preliminary results I would like to include in my presentation.
> 
> I would be happy about any comments and suggestions from your side.
> 
> Best regards,
> Cathrina
> 
> [1]: https://www.jlab.org/Hall-B/secure/hadron/meetings/18jun15/sowa.pdf
> 
> 
> MOTIVATION
> Study of excited eta states in photo production, with
> emphasis on the production of the glueball candidate eta(1405). The eta(1405)
> production in photo-production can be compared to its production in
> gluon-rich processes to shed further light on its nature.
> 
> As a reference and validation for the upper limit of the eta(1405) cross section, the
> eta' differential cross section will be determined and compared to the published g11
> results.
> 
> 
> DATA
> - run numbers: 56520-56572, 56573-56594, 56608-56646 which were event-sorted
> according to 2-2pos1neg_not_1ckaon1ctrk
> 
> - fulfilling the same trigger conditions: 3 charged tracks in 3 different sectors or
> 2 charged track in 2 different sectors with a beam energy above 3.6 GeV
> 
> EVENT SELECTION
> - two positively-charged tracks for the proton and the pi+ as well as one negatively-charged track for the pi−.
> 
> - g12_ecor.hpp package is used for the beam energy corrections
> 
> - g12_pcor.hpp package is used for momentum correction
> 
> - Energyloss was accounted with the the standard eloss corrections
> 
> - All three particles correspond to the same beam photon
> 
> - Standard cuts on vertices (Fig1, Fig2), minimum momenta(Fig3), beta Vs momentum(Fig4), fiducial volume (Fig5) and timing (Fig6) are included
> 
> - Q-value method applied on the missing eta to achieve a better background suppression (Fig7) (Black: Before, Blue: 1-Q weighted, Red: Q weighted)
> 
> 
> PRELIMINARY RESULTS
> 
> Fig8: inv. eta pi+ pi- mass spectrum
> 
> red w/ error bars: w/o Q-weight; blue: Q-weighted
> 
> Fig9: differential eta' cross section
> - GEANT based Monte Carlo events are used for efficiency correction
> following the procedure documented in the g12 wiki
> 
> - The photon flux is obtained as described in the g12 wiki
> 
> - To compare to the published g11 results, the same W binning is used
> 
> Fig8: Comparison of the diff. eta' cross section for g11 (pink) and g12 (black) data
> The distributions are in good agreement now.
> 
> -- 
> M.Sc. Cathrina Sowa
> Ph. D. student
> Institut für Experimentalphysik I
> Ruhr-Universität Bochum
> Universitätsstr. 150
> 44801 Bochum
> 
> Office: NB 2/74
> Tel.: 0234-32-23564
> Web: www.ep1.rub.de
> 
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