Vittorio Del Duca INFN LNF

85% of the total cr oss section 85% of the total cr 10 tt pairs per day 60% of the time ther e is extra radiation so that pt(tt)>15 GeV . radiation so...

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Top physics a LHC Vittorio Del Duca INFN LNF

CSN1

Roma 2 Aprile 2007

Top ID card t2/3 b-1/3

i=1,2,3

ti R L

mass set by the EWSB: mt ∼ 170 GeV

√ mt = yt v/ 2

yt ∼ 1

strong interaction with the Higgs very short lifetime: it decays before hadronising τt ∼ 10−24 s ,

−1 Γ−1 ∼ (1.5 GeV)−1 " Λ−1 ∼ (200 MeV) QCD

no spectroscopy spin transferred to decay products: Wb

Theoretical detour Top & unitarity Theoretical detour WL WL

ZL ZL

H H

WL WL

ZL fZL L

fL

ZL H

ZL H

fL fL

a0 ∼

ZL

[Chanowitz, Gallard.1985] [Appelquist, Chanowitz,1989] [Chanowitz, Gallard.1985] [FM,Niczyporuck,Willenbrock,2002] [Appelquist, Chanowitz,1989] [FM,Niczyporuck,Willenbrock,2002] s ss m2H a0 ∼ a20 ∼− 2 22 ∼ 2 s vs v vmH v − 2 ∼ 2 2 v v v





2 m sm sm f f f 2 ∼ a√0sm ∼ √ 2√sm − 2 f sm f v 2mf v v a0 ∼ a0 ∼2 −f 2 ∼ 2 v v2 v v

ZL

EWSB in the SM takes care of both EWSB in and the SM takes masses care of both boson fermion and unitarity. andmasses EWSBand areunitarity. intertwined boson top, and Higgs fermion In principle, very peculiar. It does not need to be like this! In principle, very peculiar. It does not need to be like this!

Theoretical detour Theoretical detour Top & unitarity Theoretical detour

[Chanowitz, Gallard.1985]

WL WL

WL

ZL

[Chanowitz, Gallard.1985] [Appelquist, Chanowitz,1989] [Appelquist, Chanowitz,1989] [Chanowitz, Gallard.1985] [FM,Niczyporuck,Willenbrock,2002] [FM,Niczyporuck,Willenbrock,2002]

ZL

ZL

HH H

WL WL

WL

fZL L

ZL fL

fL

ZL

H

ZL

fL fL

ZL

HL Z

fL

ZL

a0 ∼

ZL H

[Appelquist, Chanowitz,1989] [FM,Niczyporuck,Willenbrock,2002] 2 22 ss sss smm HH Hm a ∼ − ∼ a00 − ∼ ∼ − a22 ∼ 2 22 v 2 v 2 2v 2 s m vvs0 vv2v v H − 2 ∼ 2 2 v v v

√ √smf √√ m2fm2 smf smf∼ a0 ∼ sm f− f √ √ 2 2 a0sm ∼ √ v 2 sm − v 2m2 ∼v 2 2 f f f

vf sm − a0v∼ 2 v2 ZL v2 EWSB in the SM takes care of both EWSBand in the SM takes both boson fermion massescare andof unitarity. a0 ∼

∼v

v

v2

EWSB in and the SM takes masses care of both boson fermion and unitarity. top, EWSB areunitarity. intertwined boson and Higgs fermion masses In principle, very and peculiar. Itand does not need to be like this!

In principle, very peculiar. It does not need to be like this! In principle, very peculiar. It does not need to be like this!

Theoretical detour Theoretical detour Top & unitarity Theoretical detour Theoretical detour

[Chanowitz, Gallard.1985]

WL WL

WL

ZL

WL

ZL

ZL

HH

ZL

H

WL

WL

WL

WL

fZL L

fL

fL

ZL

ZfLL

ZL

ZL

H

ZL ZL

fL

fL fL

ZL

fL

ZL ZL ZL

H

HL H Z

H

[Chanowitz, Gallard.1985] [Appelquist, Chanowitz,1989] [Appelquist, Chanowitz,1989] [Chanowitz, Gallard.1985] [FM,Niczyporuck,Willenbrock,2002] [FM,Niczyporuck,Willenbrock,2002] [Chanowitz, Gallard.1985] [Appelquist, Chanowitz,1989] [Appelquist, Chanowitz,1989] [FM,Niczyporuck,Willenbrock,2002] 2 22 [FM,Niczyporuck,Willenbrock,2002] s smH m ss a00 ∼ a220 ∼ − 22 2−2∼ 2 ∼2 2H2H v 2 v v s v s vvmH H 0a0 ∼ 2 − 2 ∼ 2 v2 v2 v2

s s m a ∼ − ∼ s s m v v v a ∼ − ∼ v v v √ √smf √√ m2fm2 smf sm smf∼ a√ f− f 0 ∼ √ √ √ 2 2 2 2 2 a0sm ∼ − ∼ v 2 sm v 2 m √ f v 2m sm√ 2 ffsm f f vf v sm∼ f v mf − a0a0∼∼ a0 ∼22 − ∼ vv v2 −v 2 v2 ∼vv2v22

EWSB in the SM takes care of both EWSBand in the SM takes both boson fermion massescare andof unitarity. EWSB in the SM takescare careofofboth both EWSB in and the SM takes boson fermion masses and unitarity. boson fermion masses and unitarity. top, Higgs EWSB areunitarity. intertwined boson andand fermion masses In principle, very and peculiar. Itand does not need to be like this!

principle, very peculiar. It does not to need to be like this! InInprinciple, very peculiar. It does not need be like this!

In principle, very peculiar. It does not need to be like this!

t tbar x-section at Tevatron 8

0 0

Assume mt=175 GeV/c

Kidonakis,Vogt PRD 68 114014 (2003)

CDF Preliminary

*

*

Dilepton -1 (L= 750 pb )

8.3!1.5!1.0!0.5

*

Lepton+Jets: Kinematic ANN -1 (L= 760 pb )

6.0!0.6!0.9!0.3

*

Lepton+Jets: Vertex Tag -1 (L= 695 pb )

8.2!0.6!0.9!0.5

Lepton+Jets: Soft Muon Tag -1 (L= 760 pb )

7.8!1.7 !1.0 0.9!0.5

*

MET+Jets: Vertex Tag -1 (L= 311 pb )

6.1!1.2 !1.4 0.9 !0.4

*

All-hadronic: Vertex Tag -1 (L=1020 pb )

8.3!1.0 !2.0 1.5 !0.5

*

Combined(old SLT,all-had) -1 (L= 760 pb )

2

4

assume mt = 175 GeV

2

Cacciari et al. JHEP 0404:068 (2004)

updated on 23/03/06

compare with theory (NLO + NLL) σtt¯ = 6.5 pb (1 ± 5%scale ± 7%PDF )

7.3!0.5!0.6!0.4 (stat) ! (syst) ! (lumi)

6 8 10 " (pp ! tt ) (pb)

12

14

Cacciari, Frixione, Mangano, Nason, Ridolfi 2003

TH & EXP have comparable errors

FromTEV TEVto toLHC LHC From t tbar production Tevatron Tevatron

Tevatron LHC

LHC LHC

85% the total cross section 85% ofof the total cross section

90% the total cross section 90% ofof the total cross section

pairs per day 1010 tt tt pairs per day

1 tt pair per second 1 tt pair per second

85 %

15 %

60% the time there extra radiation 60% ofof the time there is is extra radiation that pt(tt)>15 GeV. soso that pt(tt)>15 GeV.

Almost70% 70%ofofthe thetime timethere thereis isextra extra Almost radiation thatpt(tt)>30 pt(tt)>30 GeV. radiation soso that GeV.

produced closed threshold, tt tt areare produced closed toto threshold, inin aa S [8] state. Same spin directions. 100% 3S3[8] 1 1 state. Same spin directions. 100% correlated the off-diagonal basis. correlated inin the off-diagonal basis.

canbebeeasily easilyproduced producedaway awayfrom from tt ttcan threshold.OnOnthreshold thresholdthey theyareare1S01S0 threshold. 7000 tt produced state, with opposite spin directions. No state, with opposite spin directions. No 600 tt on tape 100% correlation. 100% correlation.

10 %

90 %

10 tt pairs/day

Worry because because ofof the the backgrounds: backgrounds: Tevatron Worry (W+jets, WQ+jets,WW+jets) Worry IT a background! (W+jets, WQ+jets,WW+jets) because is is a background! 60 % with pt Worry (tt) >because 15ITGeV

LHC

1 tt pairs/sec

at hi lumi 107 tt produced/year

70 % with pt (tt) > 30 GeV

12 10

CDF Run 1 -1 Combined 110 pb

CDF Run 2 Preliminary -1 Combined 760 pb

8 2

6

mt=170

GeV/c

mt=175

GeV/c

mt=180

GeV/c

"(pp ! tt) (pb)

"(pp ! tt) (pb)

t tbar x-section: TH vs. EXP

2

12 -1

CDF II Preliminary 760 pb 10 8 6

2

4

4 2

2

Kidonakis,Vogt 1PI

0

Cacciari et al. JHEP 0404:068 (2004) mt =175 GeV/c2

0

Cacciari et al. JHEP 0404:068 (2004) Cacciari et al. ! uncertainty Kidonakis,Vogt PIM PRD 68 114014 (2003)

1800

1850

1900

1950

2000 s (GeV)

160 162 164 166 168 170 172 174 176 178 180 2 Top Quark Mass (GeV/c )

TH:

updated on 03/03/06 δm/m = 0.2 δσ/σ ∆σ = ± 6 % → ∆m = ± 2 GeV

Top mass 14

Tevatron Results (*Preliminary) D0-I dilepton

updated on 15/03/07

168.4 !12.3 ! 3.6

-1

(L= 125 pb )

CDF-I dilepton

167.4 !10.3 ! 4.9

-1

(L= 110 pb ) *

D0-II dilepton

172.5 ! 5.8 ! 5.6

-1

(L=1030 pb )

CDF-II dilepton

164.5 ! 3.9 ! 3.9

-1

(L=1030 pb )

CDF-I lepton+jets

176.1 ! 5.1 ! 5.3

-1

(L= 105 pb )

D0-I lepton+jets -1

180.1 ! 3.6 ! 3.9

-1

183.9 ! 15.7 13.9 ! 5.6

(L= 125 pb )

CDF-II Lxy

(L= 695 pb ) *

CDF-II lepton+jets

170.9 ! 1.6 ! 2.0

-1

(L= 940 pb ) *

D0-II lepton+jets

170.5 ! 1.8 ! 2.0

-1

(L= 900 pb ) *

CDF-II all-jets

171.1 ! 2.8 ! 3.2

-1

(L= 943 pb )

CDF-I all-jets

186.0 !10.0 ! 5.7

-1

(L= 110 pb ) *

Tevatron March’07

170.9 ! 1.1 ! 1.5

(CDF+D0 Run I+II)

(stat.) ! (syst.)

2

! /dof = 9.2/10

0

12.4 ! 1.5 ! 2.2

(

150

160

170

180

190 2

Top Quark Mass (GeV/c )

200

error is now at % level

Effects on global EW fits 80.70

68% CL

80.60

experimental errors 68% CL: LEP2/Tev (MW = 80.398 ± 0.025 GeV, mt = 170.9 ± 1.8 GeV) Tev/LHC

MW [GeV]

mW [GeV]

80.5

LEP1 and SLD LEP2 and Tevatron (prel.)

80.4

ILC/GigaZ

(δMW = 15 MeV, δmt = 1.0 GeV) (δMW = 7 MeV, δmt = 0.1 GeV)

SY light SU

MSSM

80.50

80.40

80.30

80.3

mH [GeV] 114 300 150

y heav 114 MH =

SM

∆α

MH

1000 175

GeV

80.20

Heinemeyer, Hollik, Stockinger, Weber, Weiglein ’07

200

H

W

W

W

160

165

W

W

δmW ∝ ln mH

170

175

180

185

mt [GeV]

δmt = 1 GeV

b

δmW ∝ m2t

SM MSSM both models

GeV = 400

mt [GeV] t

SUSY

δmW(mt) = 6 MeV

if δmW = 10-15 MeV then δmt = 1-2 GeV

Effects on Higgs mass mH > 114.1 GeV from direct search at LEP mH = 76+33-24 GeV from EW fits mH > 182 GeV from EW fits combined with direct search at LEP

use mt to estimate mH from EW corrections as mt changes, large shifts in mH

Hierarchy problem in the SM the top affects sizeably the stability of mH

δm2H

Higgs self-energy

" 2 3GF ! 2 2 2 2 = √ 2mW + mZ + mH − 4mt Λ 2 4 2π

Hierarchy problem

! " 2 2 2 2 2 (200 GeV) = mH 0 + (700 GeV) + (500 GeV) − (2 TeV)

tree

loops

shift on the Higgs mass

mh2

(200 GeV)2

top gauge higgs

#

Λ 10 TeV

$2

Fine tuning and unnaturalness Higgs self-energy 3GF (2m2W + m2Z + m2H − 4m2t )(Q2 − Q20 ) m2H (Q2 ) − m2H (Q20 ) = √ 4 2π 2

Fine tuning and unnaturalness Higgs self-energy 3GF (2m2W + m2Z + m2H − 4m2t )(Q2 − Q20 ) m2H (Q2 ) − m2H (Q20 ) = √ 4 2π 2

implies that 3GF (2m2W + m2Z + m2H − 4m2t ) Q20 = const. = O(v2 ) m2H (Q20 ) − √ 4 2π 2

because for Q20 = O(v2 )

the Higgs mass is in the range of the EW data m2H (Q20 ) = O(v2 )

Fine tuning and unnaturalness Higgs self-energy 3GF (2m2W + m2Z + m2H − 4m2t )(Q2 − Q20 ) m2H (Q2 ) − m2H (Q20 ) = √ 4 2π 2

implies that 3GF (2m2W + m2Z + m2H − 4m2t ) Q20 = const. = O(v2 ) m2H (Q20 ) − √ 4 2π 2

because for Q20 = O(v2 )

the Higgs mass is in the range of the EW data m2H (Q20 ) = O(v2 )

but for Q20 = O(MP2 l ) one must fine tune m2H (MP2 l ) to the level of v2 /MP2 l ∼ 10−33 for the cancellation to yield a figure of O(v2 )

unnatural

Weakly coupled models at the TeV scale Symmetry principles protect against power-like divergences photon self-energy

δm2γ ∝ Λ2 + m2γ ln Λ

gauge symmetry protects against quadratic divergence

A natural solution to hierarchy: supersymmetry postulate a new symmetry principle, which yields new particles that cancel the quadratic divergences of the Higgs self-energy, such that δm2H ∼ O(m2H ) ln Λ t˜

t

H

H t¯

H

H ¯t˜

δm2H ∝ GF m4t ln(mt /mt˜)

Weakly coupled models at the TeV scale Another solution to hierarchy: little Higgs models embed SM in a larger group Higgs field is a Goldstone boson from a global symmetry breaking cancel top loop with a heavy top-like quark, T T t

H

t

H

H



Λ 2 (+λ t 16π 2

shift in Higgs mass

H

H

H

T

+ λ2T δm2H



λ T mT ) = 0 f

f symmetry-breaking scale of O(1 TeV)

Λ 6GF m2t 2 mT ln = √ 2 mT 2π

EW precision measurements imply that mT is large LHC can explore mT up to 2 TeV, but huge statistics are required T

tH and tZ decays allowed

littlest Higgs larger group: SU(2)

SU(2)

U(1)

new TeV-scale states for littlest Higgs: vector-like weak-singlet quark T gauge bosons WH± WH3 weak-triplet scalar field ϕ

Little Higgs: example II

For the charge, Qt, one can measure !(tt"): marginal at the Tevatron, good at the LHC. Only known at LO. For the weak coupling to the Z, measure !(ttZ): feasible at the LHC. Only known at LO. Baur, Juste, Orr, Rainwater ‘04

shifts in ttZ axial & vector couplings ψ: SU(2) weak mixing angle

t tbar as a background tt in gg

H & qq

qqH, with H

WW

tt in single top tt jets in ttbb & ttH tt jets & ttW in SUSY searches

theory tools NLO + shower for tt production with spin correlations: [email protected] NLO single-top production with spin correlations tt + 1 jet at NLO (almost done) tt jets, ttQQ jets: ME + shower in ALPGEN, MADEVENT, SHERPA

Top & flavour physics Top & flavor physics: Vtb

Direct tree-level dominated process measurements lead to:

It is the hypothesis of unitarity of the CKM which contraints the Vti matrix elements

s the hypothesis of unitarity of the CKM which contraints the Vti matrix elements

(assuming 3 generations) unitarity implies

At present we have no direct information on each of the CKM elements of third line!

with λ 0.22 For example, the most recent CDF measurements on Bs mixing CDF measurements on Bs mixing

For example, the most recent CDF measurements on Bs mixing

implies (in goodwith agreement with SM predictions) is a good agreement the SM prediction

s a good agreement with the SM prediction

0.20 < |Vtd /Vts | < 0.22

t

Vti from Tevatron

Top & flavour physics at Tevatron

Top can decay into a real W !t ! GF mt3 (|Vtb|2+ |Vtd|2 + |Vts|2 ) 2 2 Top decay measure into a real Wwidth !t only ! GFthe mt3branching (|Vtb|2+ |Vratio: td| + |Vts| ) but can we don’t the 3 2 2 2 Γ ∼ G m + |V | + |V | ) (|V | top can decay into a real W t F ts td tb t but we don’t measure the width only the branching ratio:

but only ratio of widths is measured Γ(t → W b) |Vtb |2 R = Γ(t → W b) = 22 2 2 |V | tb Γ(t → W q) |V | + |V | + |V | td ts tb R= = Γ(t → W q)

|Vtd |2 + |Vts |2 + |Vtb |2

>0.61 at 95% >0.61 at 95%

but this only entails that |Vts|/|Vtb| and |Vtd|/|Vtb| are small it has no bearing on size of Vtb

W+ W+

ν, u ν, u

Single Top & flavour physics at Tevatron t channel σ(pp → tX) = |Vtb |2 σb + |Vts |2 σs + |Vtd |2 σd

s channel σ(pp → tX) = (|Vtb |2 + |Vts |2 + |Vtd |2 )σ s−channel

NLO: 1.85 pb

mits CDFlimits from CDF thefrom present

0.82 pb

from CDF talk at Moriond07

different Br’s combining them with R we obtain ghe into account theand different Br’s and combining them with R we obtain

from D0 talk at Moriond07 σ(pp → tbX, tqbX) = 4.8 ± 1.3 pb 0.68 ≤ |Vtb | ≤ 1

at 95 % C.L.

with 3.5 σ significance first direct measurement of Vtb

Single Top flavourphysics: physics atVLHC Top & &flavor tb NLO prediction for t+s channel

σ(pp → tX) " 250 pb

Prospects onofthe of fbV-1tb inverse at LHC, mainly from t-channel measurement Vtb extraction at LHC at 10 luminosity -1 integrated luminosity, for V =1 ! indicate a 5% error with 10 fb tb is claimed to be feasible with 5% error [ Alwall et al. , CP3, 2006] based on CMS studies

Conclusions top is one of best probes of EWSB and fermion masses measure top features (mass, spin, couplings) as well as possible to have hints on BSM physics common feature of BSM models is to have top partners EXP: Tevatron is doing a wonderful job, and lumi keeps growing LHC will be blessed by huge statistics TH: is steadily improving plethora of BSM models with top partners sophisticated MC models already available more NLO calculations are in progress