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Top A FB from Heavy New Physics Model Independent Lessons. Cédric Delaunay Weizmann Institute of Science Israel Phys.Lett.B702:364-369,2011 & JHEP 1108:031,2011 in collaboration w/ the Weizmann dreamteam : K. Blum, O. Gedalia , Y. Hochberg ,

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top a fb from heavy new physics model independent lessons

Top AFBfromHeavy New PhysicsModel Independent Lessons

Cédric Delaunay

Weizmann Institute of Science

Israel

Phys.Lett.B702:364-369,2011 & JHEP 1108:031,2011

in collaboration w/ the Weizmann dreamteam:

K. Blum, O. Gedalia, Y. Hochberg,

S.J. Lee, Y. Nir, G. Perez & Y. Soreq

August 31, 2011 | CERN

tevatron data
Tevatron Data

Basic fact:o(5) AFBmeasurementsdifferfrom SM:

CDF: l+j & ll (incl+diff)| DØ: l+j (incl) & lep AFB

whileXsec(incl+diff)is consistent withit.

Kamenik et al. ‘11

O(1) effects,

more pronounced @higherenergies

New Physics ??

Ahrens et al. ‘10

Westhoff ‘11

new physics interpretation
New PhysicsInterpretation
  • Let’s assume experiments are correct itis new physics
  • zerothorderlessonsfromO(1) NP effects in tt production:
    • strong production
    • tree-level(i.e. LO QCD)
    • mustinterfere w/ SM source

if not, >2σ tension with data!

  • 2 paths to explain data:
    • light NP | ΛNP < TeV
    • heavy NP | ΛNP > few TeV

(w/ stronger NP couplings)

  • this talk focuses on the latter

AFB & Xsec fit

(mtt>450GeV)

Grinstein et al. ‘11

heavy np eft approach

Blum et al. ’11

Delaunay et al. ‘11

Heavy NP & EFT approach
  • effective operators relevant to qq tt transitions @highmtt

above 450GeV, q≈u(dd/uu≈20%, whichweneglecthere)

non SM-like NLO corrections alsoneglected(thisispQCDafter all)

o(Λ2) :

o(Λ4) : none (if NP couplings to qq/tt are strong)

(in the perturbativesense, seelater)

interfere w/ SM

gluon production

don’tinterfere

w/ SM

heavy np eft approach1
Heavy NP & EFT approach

Blum et al. ’11

  • o(mtt2/Λ2) effects:  SM
    • CDF AFB(mtt>450) ≈ 50%cA8 ≈ 2.4/TeV2

So far, welearnthat:

    • sinceΛ>1-2TeV, NP couplings are sizable, at least o(1)
    • fromperturbativityΛ<4π/√2.4≈8 TeV
    • Implications for other observables | 1sthintsfrom(OA8)2
      • boosted top excess @CDF (Alon et al ’10 | seealsoGilad’s talk)

AFBimpliesNP/SM ~ 2 ≈ observed - 1σ

      • enhancement of the tt-tail @LHC

again, AFBimpliesNP/SM ~ 5@mtt= 1.5TeV

(cV8 = 0, sothatXsecis ok)

thereis a regionwhere EFT expansion makessense.

heavy np eft approach2
Heavy NP & EFT approach

Delaunay et al. ‘11

  • o(mtt4/Λ4) effects: all (4f-operators)2

kinematicaldiff. ~ 4mtop2/mtt2≈ o(20/50%) for mtt=800/450GeV ,

but furthersuppressed (if not vanishing) whenAFBismaximazed.

    • If neglected, a simple polar basis for non-interferingopsemerges

withinwhich NP/SM Xsec ratio & top AFB read:

    • Now, one canstart do physics&drawgenericlessons about heavy NP as a explanation of AFB anomalies.

a,b,d,e,α,β

= kinematical #’s

model independent lessons from eft
Model Independent Lessonsfrom EFT

Delaunay et al. ‘11

AFB>450~50% & NP/SM diff-Xsec < 1σ

welearnthat:

[c]=[R]=TeV-2

  • cA8 > 0.3/TeV2 (recall NP must interfere)
  • R < 3.1/TeV2
  • single chiral operatorcan’treproduceAFB

(θ=0)

Implications for LHC tt-tail

smoking gun: NP/SM > 2 @1.5TeV

(LHC verdict availablesoon…?)

last words
Last words
  • implication for boosted tops @CDF:

AFB w/in 1σimpliesNP/SM>50%

  • dijets production @LHC?
    • fromqqttit self via loop: ok!
    • @tree-levelfromqqqq: ok, provided NP couplingsgqq/gtt<1/5 !
  • any questions?