Physics Analysis Effort at UCD

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Physics Analysis Effort at UCD
Max Chertok, Tim Cox, Abrar Shaukat, Aron Soha,
Andrew Stromberg, Mani Tripathi University of
California, Davis EMU PRS Meeting Fermilab Octob
er 29, 2004

• Physics Topics
• Status report Simulations
• Future Plans

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I. Physics Effort at UCD

• The UCD group has focused its attention on Beyond
  the Standard Model Physics group. Our
  responsibilities include
• Supersymmetry CharginoNeutralino (SUSY/BSM
  TDR topic)
• Technicolor Techni-Omega (SUSY/BSM
  TDR topic)
• Model Independent searches Dibosons (MU/PRS TDR
  topic??)

• Simulation work is being carried out using
  computer clusters at CERN, Fermilab and UCD.
• One grad student is on board. More will will
  recruited in 2005. Several undergraduates worked
  over the summer (REU) and new ones have joined in
  since then.

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SUSY Trileptons
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Ni Cj Cross Sections
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Importance of Muons
mSUGRA Point m0 150 GeV m1/2 150 GeV A0
0 Sign (m) 1 At moderate to high values of
tan b, taus are the dominant decay mode, leading
to lower PT muons. At low tan b, muons are
comparable to taus.

tan b

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mSUGRA Points
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Technicolor

• An attractive alternative to SUSY.
• Provides dynamical symmetry breaking, but does
  not shed light on fundamental boson-fermion
  dichotomy.
• Techni-pions are the goldstone bosons of the
  theory. Their excited states, techni-rho(s) and
  techni-omega, will have clean signatures
• rT -gt WW- (neutral)
• rT -gt WZ (charged)
• wT -gt Z g

The final states themselves are an interesting
topic for an inclusive study. Restricting the
studies to leptons, gammas and MET is a good
strategy for early physics because it avoids jet
calibration issues.
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Associated Boson Production
Associated production of gauge bosons in the SM
is facilitated by t-channel processes as shown
here for an arbitrary pairing of bosons. For
allowed tri-boson couplings, s-channel processes
also exist. Studying precise production rates
for bosons is in itself an exercise of checking
the SM. However, in the SUSY context, it is
difficult to imagine gaugino pair production that
will not influence at least one gauge boson pair
production. Gravitino LSP models make
it necessary to consider photons as well. When
dealing with leptonic decay modes of W and Z
bosons, the contribution from final state
radiation (or, internal bremstrahung) becomes
important.
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Example D0 Results from Run I data
Based on Z e-e channel and Z nn
invisible channel, D0 Run I data did not show
any significant excess in Zg final
state. There was one event at very high value
of transverse momentum that turned out to be
consistent with the expected background,
resulting in stricter limits on anomalous Zgg and
ZZg couplings.
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CDF Run I excess in lgMET
In the first 86 pb-1 of data, CDF did a
comprehensive study of lepton gamma MET final
states. An excess in the muon gamma MET (11
events observed when 4.2-0.5 were expected)
raised the possibility of BSM physics. One
explanation consisted of R-parity violating SUSY
in a gravitino LSP scenario.
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SUSY explanation for the excess
The explanation focuses on the coupling l211 and
resonant production of the smuon. The authors
arrive at this plot
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Preliminary Run 2 results from CDF

• Latest results from inclusive lng and llg samples
  have no surprises.
• Any news on sub-samples with large MET is not yet
  available.

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II. Status Report CMS Framework
1. Signal Generators Zg CMKIN 2.1.1/Pythia
6.220 Technoicolor CMKIN 2.1.1/Pythia
6.220 SUSY CMKIN 2.1.1 Pythia 6.220 calling
ISAJET 7.69 ISAJET calculates masses mixing
Pythia does the rest 2. OSCAR 2.4.6 3. ORCA
8.1.3 4. DST/ROOT
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II.1 SUSY Distributions
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Muon Spectra from SUSY
Note that EMU chambers are very important for
full acceptance of SUSY muons (irrespective of
SUSY parameters).
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Background ttbar MET
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II.2 Zg Topology
The basic topology is lgMET. Additional leptons
may be included. The processes are mainly Wg and
Zg. (WZ, WW and ZZ will be considered later.
) We are using Pythia for mmg event generation.
At the moment this is achieved by turning on FSR
in inclusive Z events. The t-channel processes
will be generated separately and added.
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Pythia Event Generation
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Pythia Event Generation
The integral above 10 GeV/c is about 64 pb.
Compared to CDF measurement of 2.5 pb for PT
above 7 GeV/c, this is reasonable. The total
cross-section is in excess of 100 pb gt more
than 100K events in the first fb-1 of
data. This will provide us with the first
definitive study of diboson production, something
that was not possible at the Tevatron.
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Full ORCA reconstruction
We are using the Fermilab facilities for
simulation and reconstruction. This sample of
100K events took nearly one month of real-time
computing. Clearly, at this rate, we can not
study all the backgrounds required for this
process Sharing/overlap is essential.
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III. Problems and Plans

• General problems from a Joe User perspective
• Documentation of Global Muon Reconstructor cuts.
  Is user control possible/permissible?
• Does an algorithm for correcting MET for energy
  carried by muon(s) exist? . Is this up to the
  user?
• We are having problems navigating between the
  three levels of Simulations 1) Generator/Pythia
  , 2) Simulator/GEANT and 3)Reconstructor/ORCA.
  How is information correlation per particle
  supposed to be handled?
• Examples for going from 3) Rec to 1) Gen are
  obsolete, i.e., not using DST.
• Specific Problems
• Generated charge of muon, accessed via a mapping
  from reconstructed muons, is not being filled.
• Trouble getting CAL energies (for muons) from
  list of reconstructed muons.

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Conclusions and Plans

• Deliverables for the TDR
• For SUSY study, we need to provide
• - sxBR for various mSUGRA points.
• - Distribution of Event variables and Particle
  variables
• - Detector efficiencies/acceptances versus
  these variables.
• - Discovery/limit reach versus mass parameters
  (as a function of int. lum.)
• - Example counting experiment with realistic
  backgrounds/systematics.
• 2. Similar set of plots for Techni-omega search
• - Smaller parameter space to deal with.
• - Several backgrounds channels are common.
• 3. We need a large set of backgrounds with the
  lgMET topology. At the minimum
• Wg, Zg, WW, WZ, ZZ
• t-tbar, Wb, Zb (with b-gte,m)
• Fakes Jet-gte, m, g and e -gt g
• Our goal is to produce (at UCD/FNAL) the samples
  that are not being generated by CERN (unique for
  our studies).