Search for Technicolor via wT

1

• Search for Technicolor via wT
• Abrar Shaukat, Aron Soha, John Smith, Andrew
  Stromberg,
• Mani Tripathi
• University of California, Davis
• Brajesh Choudhary, Manoj Jha
• University of Delhi, India.
• CERN
• June 9, 2005

2
Search for Technicolor via wT

• We are working within the Technicolor Strawman
  Model that has been implemented in Pythia.
• High mass states such as rTC, wTC, hTC gt Rich
  Spectroscopy. Possible simple 2-body decay modes
  instead of long chains/cascades! Also, one of
  the few possibilities of conducting a search with
  precise reconstruction of 3-body masses and
  internal decay angles.
• P. Kreuzer has studied the CMS reach for rT. We
  are focusing on the Neutral, Iso-Singlet, spin-1
  state wT

3
Decay Modes

• 1. One of the major decay modes is wT -gt W pT
  (charged technipion). This is a less attractive
  final state due to missing energy.
• 2. Try to look for fully reconstructible modes.
  One choice wT -gt m m- B.R. 0.5-4.5 (next
  slide) To first order it looks just like Z .
  Electro-weak production and decay. So, we need
  to try and disentangle.
• 3. Other choices (3-body)
• wT -gt g pT0 pT0 -gt m m- (pT0 -gt b b-bar
  is Higgs-like and studied elsewhere).
• and,
• wT -gt g p/T0 p/T0 -gt m m-
• 4. Further choice (4-body or effective 3-body in
  case of MET)
• wT -gt Z pT0 pT0 -gt m m- and Z-gt neutrinos
  (Z -gt m m- is again Higgs-like)
• and,
• wT -gt Z p/T0 p/T0 -gt m m- and Z-gt neutrinos
• Here the MET is constrained by the technipion.
  Restricting the studies to leptons, gammas and
  MET is a good strategy for early physics because
  it avoids jet calibration issues.

4
Branching Ratio for wT -gt m m-
We generated 3 sets of points in the mass plane
with the mass ratio (pi/omega) of 0.5, 0.75 and
1.0). The dimuon decays are quite important
for a large part of the mass-plane. This study
is very similar to a Z-prime study. The
cross-sections must be made small, else this is
mostly excluded by the Tevatron.
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Radiative Decays of wT
Most important decay channel for our study. The
events are tagged by a well-isolated photon with
a high transverse momentum. This channel is
not very useful if the technicolor masses are
degenerate (case 1.0). Even if there is a small
mass-split, the photon will be too soft.
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PT Branching ratios two options
b-bbar
We can convolute the H-gtb-bbar efficiencies with
the gamma efficiency for this channel (and the wT
-gt g pT0 B.R.) to compute the overall
efficiency. The discontinuity at 350 Gev is due
to t-tbar. The dimuon channels have very small
B.R. (10- 4) but they lead to a 3-body mass
reconstruction when combined with the gamma.
m m- (x 103)
PT Mass (GeV)
b-bbar
m m- (x 103)
PT Prime Mass (GeV)
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B.R. for ATLAS points
As we have seen, B.R. are very sensitive to mass
differences between wTC and pTC . If Technicolor
mass splitting are reasonable, radiative decays
may be quite important. This table shows the
B.R.s for the ATLAS mass points.
In the degenerate case, decay to WW- dominates
8
Production Cross Sections

• Two production mechanisms
• Vector Dominance -mixing with gauge bosons.
  similar to gP -gt r -gt pions
• Anomalies not involving techni-resonances.
• Some sample points

g pT0 g pT0
Z pT0 Z pT0
Effect of B.R. changing with mass difference.
Because of inherent mixing in the production
mechanisms, Drell-Yan production of dimuons is
also mixed in by Pythia. We are planning to
study the g pT0 g pT0 channel in greater
detail. The cross sections are small but
essentially background free.
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Background Associated Bosons
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. In our case, Zg production, with Z-gt
dimuons is relevant. When dealing with
leptonic decay modes of Z bosons, the
contribution from final state radiation (or,
internal bremstrahung) becomes important.
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Pythia Cards

• Included here for the record
• MSUB 3641 f fbar -gt gamma
  pi_T0
• MSUB 3651 f fbar -gt gamma
  pi_T0'
• MSUB 3661 f fbar -gt Z0
  pi_T0
• MSUB 3671 f fbar -gt Z0
  pi_T0
• MDME(4001,1) 1 pi_tc0 -gt mu mu-
• MDME(4017,1) 1 pi'_tc0 -gt mu mu-
• MDME(4027,1) 1 rho_tc0 -gt gamma
  pi_tc0
• MDME(4028,1) 1 rho_tc0 -gt gamma
  pi'_tc0
• MDME(4029,1) 1 rho_tc0 -gt Z0
  pi_tc0
• MDME(4030,1) 1 rho_tc0 -gt Z0
  pi'_tc0
• MDME(4073,1) 1 omega_tc -gt gamma
  pi_tc0
• MDME(4074,1) 1 omega_tc -gt Z0
  pi_tc0
• MDME(4075,1) 1 omega_tc -gt gamma
  pi'_tc0
• MDME(4076,1) 1 omega_tc -gt Z0
  pi'_tc0

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Zg background
We are using Pythia for mmg event generation. At
the moment this is achieved by turning on FSR in
inclusive Z events. The radiative events can
have a photon with substantial transverse
momentum (next slide). The t-channel processes
will be generated separately and added.
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Zg Background rate
The integral above 10 GeV/c is about 64 pb (for
t-channel only). 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 above 10 GeV in the first
fb-1 of data. In the region above 100 GeV, this
background is comparable to the signal.
Moreover, the photon from the wT will have an
end-point at half the mass value.
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Detailed simulation CMS Framework
1. Signal Generators Zg CMKIN 2.1.1/Pythia
6.220 Technicolor CMKIN 4.3.1/Pythia
6.227 2. Detector Simulation Zg OSCAR
2.4.6 Technicolor OSCAR 3.7.0 3. Event
Reconstruction Zg ORCA 8.1.3 Technicolor
ORCA 8.7.3 4. DST/ROOT We use Fermilab
computing facilities for simulations.
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Full ORCA reconstruction
We are using the Fermilab facilities for
simulation and reconstruction. A 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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pT Reconstruction
First look at event topology via full ORCA
reconstruction. 2,000 events generated (with PT
mass 110 GeV). Efficiency is high (60). The
production process in Pythia mixes in the
Drell-Yan events which have to be separated
out. The next step is to understand the 3-body
mass to reconstruct the wT.
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Conclusions and Plans

• Deliverables for the TDR
• For Techni-omega search, we need to provide
• - sxBR for various mass scales.
• - Detector efficiencies/acceptances.
• - Discovery/limit reach versus mass parameters
• - 2-body 3-body mass reconstruction with
  realistic backgrounds/systematics.
• - Several backgrounds channels are common.
• We need a large set of Zg events and possibly
  even study Zg (?).