Search for the 2nd KK states of the mUED model at the LHC
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Transcript of Search for the 2nd KK states of the mUED model at the LHC
Search for the 2nd KK statesof the mUED model
at the LHC
Kang Young LeeKonkuk U.
Seoul
YongPyong 2012@ Greenpia, Yong Pyong 2012. 2. 20-23
Based on
Sanghyeon Chang, Kang Young Lee, Jeonghyeon Song
• Phys. Lett. B708, 144 (2012).
• Phys. Rev. D, to appear
• In preparation
Outlines
• Introduction
• mUED model
• Search for the 2nd KK Higgs bosons
• Search for the 2nd KK W boson
• Search for the 2nd KK Gluon (preliminary)
• Summary
Introduction : mUED at the LHC
• The phenomenology of the mUED model is definitely fixed with only one model parameter, 1/R.
• The 2nd KK states are comparable to (or better than?) the 1st KK states to be studied at colliders.
• Only the 2nd KK CP-odd Higgs can be found at the LHC.
• The 2nd KK W boson is a good candidate to be found at the early LHC.
• The ttbar resonance can give a (first) direct bound on the mUED at the Tevatron via the 2nd KK gluon.
The universal extra dimension model (UED)
Virtues and drawbacks
The first vs. the second KK states
• m(2) ~ 2 m(1) (m(n) ~ )
• The first KK states are KK parity-odd, while the second KK states are KK parity-even.
• The first KK states are produced in pairs, while the second
KK states are singly produced due to the KK parity.
• The first KK states decay into the LKP + soft SM particles.
• The second KK states can decay into SM particles via loops.
• Comparable masses, less productions (loops), better detections (resonances).
20
2)/( mRn
KK expansions
Particle Spectra
1/R = 500 GeV, mh = 120 GeV, ΛR = 20
Search for the 2nd KK Higgs bosons
Higgs masses
where
Top quark masses
where
diagonalized by
In 4D, the effective lagrangian is given by
CP-odd KK state is produced via gluon fusion,while CP-even state canNOT.
The peak is very sharpcompared with the SM Higgs.
Productions
Assuming ∫L~ 100 fb-1,
about 10,000 will be
produced
for 1/R = 400 GeV.
About hundred events of
are expected.
Background study
Irreducible background is small. (e.g. )
Reducible background is huge from QCD events. ( of order mb)
Search for the 2nd KK W boson
W(2) masses
where
Direct production
indirect production
pp → W’ → eν / μν at the early LHC
Selection criteria
ET > 30 GeV
Isolation radius
CMS collab., PLB 698, 20 (2011)
MT distribution
Soft SM particles
We expect that the
direct bound of the
mUED will be obtained
from the search for the
W’ boson at the early
LHC.
Soft SM particles
It is difficult to probe
the mUED through this
channel at the
Tevatron.
Search for the 2nd KK Gluon (preliminary)
pp → G(2) → ttbar (resonance)
Summary
• The loop-induced decays of the 2nd KK states can be substantial in the mUED model.
• The CP-odd 2nd neutral KK Higgs can be observed at the LHC in the future.
• The 2nd KK W bosons will provide a direct bound on the mUED model at the early LHC (2012?).
• The 2nd KK gluon provide a direct bound on the mUED model at the Tevatron through the resonant ttbar channel when Λ=50/R.
t1 – t2 mixing angle