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Tuning for cluster-track matching parameter and Higgs mass

It is recommended to tune parameters for Cluster-Track matching process dependantly( ref: http://www-jlc.kek.jp/http://www-jlc.kek.jp/subg/offl/lib/docs/cmbtrk/main.html ). To this end, I generated 20k events of $e^+e^-\rightarrow ZH$ and study the invariant mass resolution using the decay mode of $Z->\nu\bar{\nu}$ and $H\rightarrow hadron$. In the study, the center of mass is 300 GeV, and the mass of higgs was 120 GeV. Event was generated using Phythia5.7. The parameter of cluster track matching, ENSGHD, is changed from 1.0 to 3.0 by 0.5 step. Standard parameter for the case of 2 Tesla magnetic field was 2.0 for both ENSGHD and ENSGHD. The Higgs mass distributions for each parameter set are shown in Fig. 11. For the comparison, similar distribution for the case of 2 Tesla solenoid field and for the case of the scan of the parameter, EMSGEM, of the Elemag Calorimeter are shown in Fig. 12 and Fig. 13, respectively.
  
Figure 11: Reconstructed invariant mass of Higgs. The parameter of cluster track matching, ENSGHD, is changed from 1.0 (left-top figure) to 3.0 (left-bottom ) figure by 0.5 step. The solid curves in the figure are gaussian fit in the mass region from 112 GeV to 122 GeV.
\begin{figure}\centerline{\epsfxsize=16cm \epsfbox{ghdscan.eps}}\end{figure}


  
Figure: Same as Fig.13, but the solenoid field is 2 Tesla. Fitted mass region is from 114 to 124 GeV.
\begin{figure}\centerline{\epsfxsize=16cm \epsfbox{ghdscan.2T.eps}}\end{figure}


  
Figure: Same as Fig.13, but the parameter EMSGEM for Elemag calorimeter are changed for comparison with the case of Fig.13
\begin{figure}\centerline{\epsfxsize=16cm \epsfbox{gemscan.eps}}\end{figure}

First of all, the histograms in Fig. 13 shows no difference despite the change of the parameter, ENSGEM. This confirms that EMC cluster is not used in Cluster-Track matching algorithm as was told by K.Fujii.

Comparing the Fig. 11 and Fig. 12, we see that

In the Fig. 14, we compare the invariant mass distribution of Higgs for the case of 3 Tesla detector and 2 Tesla detector. We see, in addition to the shift of peak position, that tail part in the 3 Tesla case is larger than 2 Tesla case. We are loosing particles which cases the shift of peak and increase of tail in the mass distribution. This would be due to the inproper us of ENSGHD parameter.

In the Fig. 15, we compare 3 Tesla case and ENSGHD = 1.0 with 2 Tesla and ENSGHD=2.0. We see both distribution is consisten within statistical error. Since ENSGHD=2.0 is used as a standard value so far, ENSGHD=1.0 should be used as a standard calue for 3 Tesla case, to get similar results as 2 Tesla case.


  
Figure 14: Comparison of Higgs mass distribution between 2 Tesla and 3 Tesla. ENSGHD is 2.0 in both cases.
\begin{figure}\centerline{\epsfxsize=16cm \epsfbox{hmass.2Tvs3T.eps}} \end{figure}


  
Figure 15: Comparison of Higgs mass distribution between 2 Tesla and 3 Tesla. ENSGHD for 2 Tesla case is 2.0, while the one for 3 Tesla case is 1.0.
\begin{figure}\centerline{\epsfxsize=16cm \epsfbox{hmass.2Tvs3T1.0.eps}} \end{figure}

next up previous
Next: About this document ... Up: Calorimeter hit signal and Previous: Clustering algorithm
akiya miyamoto
2000-01-21