Edward Estrada Kevin Fiedler (graduate student at CalTech) Alec Jenkins Gleb Oleinik (graduated from CU) Uriel Nauenberg. SiD02 Beam Calorimeter Studies. CMSSM Parameter Points Analyzed.
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Kevin Fiedler (graduate student at CalTech)
Gleb Oleinik (graduated from CU)
Uriel NauenbergSiD02 Beam Calorimeter Studies
University of Colorado - Boulder 2011
CMSSM Parameter Points Analyzed
• Studies focused on WMAP points at which there is a small difference between the and masses.
• M. Battaglia, A. De Roeck, J. Ellis, F. Gianotti , K.A. Olive, and L. Pape, Updated Post-WMAP Benchmarks for Supersymmetry.
• Events in which the initial e- and e+ are undetected are made of low energy particles and possibly have high transverse momentum– the common features of most SUSY events.
Beam Calorimeter Electron Detection Efficiency
• Oleinik’s efficiency study uses the coordinate system shown above.
• A clustering algorithm is used to separate energy deposits in the BeamCal due to electrons from those due to beamstrahlung.
• The expected beamstrahlung deposit per tile is first subtracted, leaving candidate electron shower axes.
• A cylindrical cut is made by discarding tiles outside the approximate Moliere radius of each axis (5mm).
• Energy peaks of electron deposits are typically deeper than peaks due to beamstrahlung.
• A depth cut is made, discarding tiles 30mm from the surface of the BeamCal.
• The average beamstrahlung deposit for each cluster axis is subtracted.
• The efficiency of electron detection is calculated for various points in the BeamCal and an efficiency table is made by interpolating between these points.
Signal Analysis of the
High Energy Electron Events Removed by the BeamCal and Main Detector
BeamCal Comparison at the CMSSM point C’
= 9.6 GeV
m0 = 85, m1/2 = 400, tan(beta) = 10, A0 = 0, sign(mu) = +
BeamCal Comparison at the CMSSM point D’
= 7.5 GeV
m0 = 110, m1/2 = 525, tan(beta) = 10, A0 = 0, sign(mu) = -
Energy Cut Comparison at the CMSSM point B’
= 14.1 GeV
m0 = 60, m1/2 = 250, tan(beta) = 10, A0 = 0, sign(mu) = +
• A spectrum fitting method is used to determine the masses of the and .
• SUSY data are generated at a range of parameter points, and a spectrum is made by comparing the new generated data to the original.
• Standard Model data are not regenerated for each point, and so subtraction of the background is complete. Because of this, the spectrum fit depends on the effect of the cuts on the SUSY data, not the visibility of the of the signal over the background.
Measured Masses Input Masses
174 +1 -1 GeV 170.6 GeV
164 +.5 -.5 GeV 161.0 GeV
• The signal can not be observed without the BeamCal in the region of parameter space where there is a low - mass difference.
• Although the spectrum fitting method does not depend on the visibility of the signal, those parameter points at which the signal is overwhelmed by the background are the same as those for which the spectrum fitting method does not lead to a unique set of parameters.
D. Wagner, Introduction to Supersymmetry at the NLC, http://hep-www.colorado.edu/~nlc/SUSY_Wagner/susy/susynlc.html
S. Martin, A Supersymmetry Primer, arXiv:hep-ph/9709356, December 10, 2008.
M. Battaglia, A. De Roeck, J. Ellis, F. Gianotti , K.A. Olive, and L. Pape, Updated Post-WMAP Benchmarks for Supersymmetry, arXiv:hep-ph/0306219v1 June 23, 2003.
N. Arkani-Hamed, G.L. Kane, J. Thaler, and L.T. Wang, JHEP 0608, 070 (2006) [arXiv:hep-ph/0512190].
Uriel Nauenberg's Supersymmetry Group. http://hep-www.colorado.edu/SUSY/susynlc.html
K. Fiedler, G. Oleinik, U. Nauenberg, Electron Detection Efficiency of the SiD02 Beam Calorimeter for Various Beamstrahlung Intensities, December 12, 2010, http://hep-www.colorado.edu/~uriel/Beamstrahl_TwoPhoton-Process/effic3.ps
P. Bechtle, M. Berggren, J. List, P. Schade, and O. Stempel, Prospects for the study of the $\stau$-system in SPS1a' at the ILC, arXiv:0908.0876v1 [hep-ex], August 6, 2009.
W. Porod, Spheno, a program for calculating supersymmetric spectra, SUSY particle decays and SUSY particle production at e+ e- colliders, arXiv:hep-ph/0301101, February 1, 2008.
F.A. Berends, P.H. Daverveldt and R. Kleiss BDK. Monte Carlo simulation of two-photon processes. Comp. Phys. Commun., 1986.
K. Fiedler, Supersymmetric Signal Analysis and Mass Reconstruction of the Chargino (\chionep) at the International Linear Collider, March 9, 2011, http://hep-www.colorado.edu/SUSY/Fiedler_Chargino_Analysis.ps
C. Long, Undergraduate Honors Thesis, Advisor: U Nauenberg, Department of Physics, High Energy Physics Group, University of Colorado at Boulder, August 5, 2010.
C.F. Berger, J.S. Gainer, J.L. Hewett, B. Lillie, and T.G. Rizzo, General Features of Supersymmetric Signals at the ILC: Solving the LHC Inverse Problem, arXiv:0712.2965v2 [hep-ph], February 28, 2008.
A. Hahn, An Analysis of Selectron Masses Including the Effects of Beamstrahlung, August 16, 2004, http://hep-www.colorado.edu/SUSY/hahn_selectron.ps
Data Generation and Reconstruction
PYTHIA - Z production, W production, Compton and Bhabha scattering
BDK - Two-photon process
• The SUSY spectrum is calculated using SPheno, and SUSY data are generated using PYTHIA 6.4.
• Data are reconstructed using MCFast from the org.lcsim framework, modified to include the BeamCal detection efficiencies.
BeamCal Comparison at the CMSSM point G’
m0 = 115, m1/2 = 375, tan(beta) = 20, A0 = 0, sign(mu) = +
Energy Cut Comparison at the CMSSM point SPS1a’
m0 = 70, m1/2 = 250, tan(beta) = 10, A0 = -300, sign(mu) = +
BeamCal Comparison at the CMSSM point I’
m0 = 175, m1/2 = 350, tan(beta) = 35, A0 = 0, sign(mu) = +
• Initial values are obtained by holding tan(beta) = 10, sign(mu) = +, A0 = 0, and then varying m0 and m1/2 over wide ranges.
• Precise measurements of the parameters are then made in the minimum m0 – m1/2 regions.
Cut Comparison at the CMSSM point D’
m0 = 110, m1/2 = 525, tan(beta) = 10, A0 = 0, sign(mu) = -