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# [bds 231] Physics effects of ILC parameters

*Subject*: [bds 231] Physics effects of ILC parameters
*From*: Klaus Moenig <klaus.moenig@xxxxxxx>
*Date*: Wed, 7 Dec 2005 16:55:12 +0100 (CET)

Dear colleagues,

`to get a first idea of effect the ILC parameters on physics I looked into the
``Higgs recoil mass measurement at 350 GeV. The attached file shows the sqrt{s}
``spectrum for nominal (solid) lowP (dashed) and highL (dotted) in the upper plot
``and the reconstructed recoil mass in the lower plot. The plot contains neither
``beam spread nor detector. However since, as you see, the additional smearing
``moves the events from the peak to far away, this doesn't matter for a crude
``estimate of the effect.
`

`For lowP and highL there is a factor 0.7 less events in the peak for the same
``luminosity, so for zero background the statistical error gets larger by a
``factor 1/sqrt(0.7). Taking the TESLA TDR as reference and integrating over the
``relevant region the signal/background is about 1/1. Since the background should
``be little effected by the beam parameter also this value goes to 0.7/1. Since
``the statistical error in presence of background has to be divided by
``sqrt(purity) you need in the end a factor 1.8 more luminosity for lowP and
``highL compared to norm to arrive at the same statistical error. For the
``systematics you can only guess that it increases as well with the
``beamstrahlung.
`

`Of course this applies to exactly this one analysis and has to be redone for
``every channel of interest. However the factor 0.7 comes from the number of
``events in the peak at nominal beam energy, so it should be roughly applicable
``for all channels where narrow resonances are involved.
`
Best wishes,
Klaus
+------------------------------------------------+
| Klaus Moenig e-mail: Klaus.Moenig@xxxxxxx |
| DESY, Zeuthen or: Klaus.Moenig@xxxxxxx |
| |
| Tel.: +49 33762 77271 Fax: +49 33762 77330 |
| Mob.: +49 160 8550906 |
+------------------------------------------------+

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