User:Masa

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Search for the exotics in \gamma p \to \ p \pi^{+}\pi^{-}[\eta].

One of the mission in this study is finding the exotics which cannot be explained by quark model.
Our reaction is pretty simple for finding these at CLAS detector;
Only one neutral particle is seen and the missing mass can be computed from the kinematics relations.
In this note, we try to explain how to analyze data in g6c and g12.
Then, we would like to make the concrete argument for the exotic resonance.

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Preparation for the data analysis

Firstly, we have to check out data form jlab silo[1]. We usually seek under the directory /mss/clas/g*/production/pass*/v*/skims/ and cached under the directory /cache/mss/clas/g*/production/pass*/v*/skims/ using "jcache". Actual command should be 

 jcache /mss/clas/g*/production/pass*/v*/skims/prong*/filter*.A*.pass*.prong*.*
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Filter the data

I started to read Mina's paper in g6c.

These cuts will be common in all filters

Beam energy cuts: 4.8 [GeV] Timing cuts: -1 - 1 [ns] z-Vertex: -110 - -91 [cm]

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Remained tasks

  • Comparison between the BNL MPS and the JLab CLAS; topological and trigger cuts are different.
  • Understand the meaning of the background studies more clearly. 
 The key feature is decomposing η and non-η type resonance using Dalitz plot.
 Extra reaction produces π0 .
  • Consult the Regge-pole phenomenology for seeing the acceptance-corrected distribution. 
 Regge-pole model is very effective approach especially in the non-perturbative region.
    • Rep. Prog. Phys. 34 995 
  This article explains the fundamental principles of Regge theory in pedagogical way.
    • Rep. Prog. Phys. 41 676 
  Some discussions seems to be dated; however, section 5 is still useful for the beginner like me.
  • Focus on the derivation of partial wave analysis. ( PRD 11 633, PRD 56 7299 and workshop@bes )
    • PRD 11 633 
  This article nicely develop the fundamental ideas of spin density matrix.
  Kinematics is described in the GJ frame ( s-channel ) because the reflection positivity is also seen easily.
  ( This operation seems to be the same idea of Wick rotation. I will check this later. )
  The matrices diagonalizing algorithm is based on Cholesky decomposition (in part of LU).
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Some plans for the next week

  • Access to the data in g6c using silo.
  • Start filtering for these 10 sets.
  • Take more time for understanding the formalism and physical significance.
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