tevatron non-susy bsm: searches for physics beyond the sm and mssm david stuart

Tevatron Non-SUSY BSM:Searches for Physics Beyond the SM and MSSM

David StuartUniversity of California, Santa Barbara

DIS 2007, MunichApril 2007

2David Stuart, DIS2007

OutlineThere are two categories of searches:

1. Model driven• New Dimensions, New Interactions, or New Particles• Specifically optimized

2. Signature driven• Look for deviations from SM in specific final states• Broadly optimized

Most recent results use ≈ 1 inverse femtobarn.


New Gauge Boson: Z’ ee

Signature: Di-electron mass peak

Backgrounds:Drell-Yan (Irreducible & dominant)QCD fakesDiboson and top

e+

q

q

e-

Z’

Model: Many unification models






e+

q

q

e-

Z’


New Gauge Boson: W’ e e+

q

q

W’

Signature: High transverse mass peak

Backgrounds:Tail of WQCD (suppressed w/ cuts on jets w/ ET>15)



New Gauge Boson: W’ e

Limits assume SM couplings

e+

q

q

W’

Signature: High transverse mass peak

Backgrounds:Tail of WQCD (suppressed w/ cuts on jets w/ ET>15)


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RS Extra Dimensions: G γγG

Signature: Di-photon mass peak

Backgrounds:QCD jets faking photonsSM di-photon production (dominant at high mass)

David Stuart, DIS2007

Model: Strongly coupled graviton in Randall-Sundrum warped extra dimension

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RS Extra Dimensions: G γγG

Signature: Di-photon mass peak

Backgrounds:QCD jets faking photonsSM di-photon production (dominant at high mass)



Limits:Comparable to di-leptonsMass limits to 850 GeV when γγ and ee combined

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RS Extra Dimensions: G γγ or eeA similar search at D0 combines ee and γγ at the analysis stage as di-EM.


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RS Extra Dimensions: G ZZ eeee

Signature: Four electron mass peak

Backgrounds:Very low backgrounds (0.02 ± 0.02 events)so use very loose electron selection.

Select Zee with a 2.

~3 GeV

Signal region:2 < 50 and M > 500



ee

e

e

G

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Large Extra Dimensions: Monojet + Missing ET

Model: ADD large extra dimensions

Backgrounds:


Signature: 1 or 2 jets + MET

KK3914

39830

19230

15713

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Backgrounds:



3914

39830

19230

15713No shape difference,so predicted from data.

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Backgrounds:



3914

39830

19230

15713

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Excited electron: e* eγ

e

e

e

Model: Compositeness

Signature: eγ mass peak

Backgrounds: DY+γ Zee with brem

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Model: Compositeness

Signature: eγ mass peak

Backgrounds: DY+γ Zee with brem

Excited electron: e* eγ

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2nd generation Leptoquark:

Signature: + 2 jets + METj mass peak

Backgrounds:W+jets & top

Model: LQ carries both color and lepton #

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2nd generation Leptoquark:

Signature: + 2 jets + METj mass peak

Backgrounds:W+jets & top

Model: LQ carries both color and lepton #

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4th generation quark: b’ bZModel: 4th gen quark w/ small couplings to 1st three generations.

Signature: Z+ jetsAt least 3 jets, ET>30 GeVLarge total jet energy, JT

Background: Z+ jetsPredicted from the data by fitting ET spectrumand modeling JT

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Data consistent with prediction,limits obtained at 0.5 pb and 270 GeV.

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4th generation quark: b’ bZ

Top in W+jets is used as a cross-check of the MC-less method

W+jets Control Sample

Model: 4th gen quark w/ small couplings to 1st three generations.



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Model Independent Searches

Making a search model-specific increases its sensitivity at the cost of breadth.

Making a search less specific increases its breadth at the cost of sensitivity.

There are several model-independent search results from the Tevatron…

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Search for high pT Z

Background: Z+ jetsQCD from same-sign dataOthers predicted with MC

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Search for high pT Z

Background: Z+ jetsQCD from same-sign dataOthers predicted with MC

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Search for Z + X

XExpected

e+e-

Observed

e+e-

Expected

Observed

Leptons 1.6 ± 0.3 3 2.4 ± 0.4 2

Photons 12.4 ± 1.5 14 15.0 ± 1.8 14

HT 36.4 45 41.3 53

MET 85.4 ± 12.3 97 55.9 74

+4.9 -5.8

+5.0 -5.2

+9.7 -5.8

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≥2 jets e Same signee/

SM 2.9±1.5 1.5±0.8Data 2 0

SearchRegion


Search for Dilepton + X

Background: Z+jets, Z+γ, Diboson, top, QCD

where X = γ, HT, MET, high ET jets, b-jets, leptons

Highest HT event looks top-like,with a b-tag and 3 jets.

“Unusual” dileptons + 2j + HT>400

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•Partially motivated by Run I ee+γγ+MET candidate event

γγe γγ γγγ γγ+METMET>75

SM 6.8±0.8 0.8±0.1 2.2±0.7 0.24±0.22

Data 3 0 4 1


Search for γγ + X, where X = e//γ/MET

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Search for Stable CHArged Massive Particles (CHAMPs)

If heavy, a CHAMP would penetrate like a muon, but it would be slow.D0 searched with muon chamber scintillator timing, and CDF searched with its TOF counters.

Limits on A of 10 fb if weakly interacting and 48 fb if strongly interacting.

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Summary

• CDF and D0 have varied searches, both model specific and model independent.• Some fluctuations seen, as one would expect in a large ensemble of measurements.

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Summary


• The Standard Model wins again.

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Summary



• But, we are not done hammering away at it:• The Tevatron expts will collect about 4x more data.

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Summary



• But, we are not done hammering away at it:• The Tevatron expts will collect about 4x more data.• There is a Larger Hammer Coming.

tevatron non-susy bsm: searches for physics beyond the sm and mssm david stuart

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