1. How well do we need to know the luminosity spectrum at 3 TeV CLIC? Lucie Linssen, CERN on behalf of the CLIC physics and detector study, material principally from Philipp Roloff, Jean-Jacques Blaising, Frank Simon, Lars Weuste Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 1

2. purpose and outline Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 2 Outline: The nominal CLIC luminosity spectrum Ad-hoc variation of the spectrum Impact on slepton results Impact on gaugino resluts Impact on squark results The aim of this talk is to illustrate how the uncertainty in the knowledge of the luminosity spectrum can influence the physics results at a 3 TeV CLIC machine. Three benchmark examples are presented CLIC CDR link: http://arxiv.org/abs/1202.5940

3. nominal CLIC luminosity spectrum Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 3  fraction of the luminosity that is above √s’/√s 3 TeV √s’ energy spectrum 500 GeV √s’ energy spectrum

4. ad-hoc spectrum variation Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 4 While waiting for the result of the simulation study, telling us how well we can measure the luminosity spectrum in situ using large-angle bhabha events (see next talk by Stephane Poss), an ad-hoc approach was tried. Start from nominal GuineaPig output for both single beam spectra: then move 5% of the events for both beams from the peaks to the tails (green) and vice versa (red) Considered an conservative approach => aim is to study impact on physics results ad-hoc modified luminosity spectra 3 TeV blow-up of peak region

5. detector benchmark studies for CDR Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 5 Six benchmark studies reported in the CDR Full physics simulation and reconstruction studies with beam background overlay (γγ => hadrons): 3 TeV (2 ab -1 ) 500 GeV (500 fb -1 )    For three of these channels the impact on the knowledge of the lumi spectrum was studied using the ad-hoc luminosity spectrum change.

6. slepton production Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 6 Slepton production at CLIC very clean SUSY “model II”: slepton masses ~ 1 TeV Channels studied include  Leptons and missing energy Masses from analysis of endpoints of energy spectra smuon sneutrino

7. uncertainty due to lumi spectrum Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 7 Result with perfect knowledge of the luminosity spectrum: Result when ad-hoc variances of luminosity spectrum are used: Data are generated with nominal spectrum. Results are fitted using ad-hoc lumi spectra. Shift in results << than statistical error Except e R => shift ~100% of statistical error https://edms.cern.ch/document/1157230/2 Jean-Jacques Blaising ~

8. squark production Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 8 e.g.  for squark mass ~1.1 TeV  two jets + missing energy Jet clustering: k T with  R=0.7 TIGHT timing

9. uncertainty due to lumi spectrum Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 9 Result with perfect knowledge of the luminosity spectrum: Result when ad-hoc variances of luminosity spectrum are used: Data are generated with nominal spectrum. Results are fitted using ad-hoc lumi spectra. Results shift by << statistical error (M c is not sensitive to lumi spectrum) https://edms.cern.ch/document/1158627/1 Frank Simon, Lars Weuste

10. gaugino pair production Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 10 SUSY “model II”: Pair production and decay: 82 % 17 % Separation using di-jet invariant masses (test of PFA) Reconstructed W energy in chargino events

11. uncertainty due to lumi spectrum Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 11 Result with perfect knowledge of the luminosity spectrum: Result when ad-hoc variances of luminosity spectrum are used: Data are generated with nominal spectrum. Results are fitted using ad-hoc lumi spectra. Shift in measured masses: ~50% of statistical error Shift in measured cross sections: ~100% of statistical error https://edms.cern.ch/document/1160162/2 Philipp Roloff

12. summary Lucie Linssen, FCAL workshop, Zeuthen May 9th 2012 12 To mimic the uncertainty in the knowledge of the luminosity spectrum, an ad-hoc variance in the lumi spectrum was generated. This ad-hoc variance constitutes a pessimistic scenario. The ad-hoc variance was used in the analysis of three benchmark studies at 3 TeV Slepton production Squark production Gaugino production In general, the precision of the physics results (mass and cross section measurements) is dominated by statistical errors. Due to the use of the ad-hoc spectrum, the results shift by: less than statistical error in most cases up to statistical error in a few cases