The Top Quark Charge Asymmetry at the LHC Recent ATLAS Measurements and Strategies for the LHC

The Top Quark Charge Asymmetry at the LHC Recent ATLAS measurements and strategies for the LHC

F. Rubbo (IFAE, Barcelona) Status aer LHC@7-8 TeV

Null results from direct The Higgs discovery completed the beyond-SM searches Standard Model at the ElectroWeak scale up to ~1 TeV

- The Top Charge Asymmetry at the LHC - 2 The Top Quark – gateway towards New Physics

Important role in EW • Heaviest parcle, m ~173 GeV top symmetry breaking • Yukawa coupling ~1 and BSM models.

Measurements of top quark properes, such as the charge asymmetry in the producon of top quark pairs, might provide hints of new physics beyond the Standard Model.

- The Top Charge Asymmetry at the LHC - 3 The Top Quark – Pair producon at the LHC

Large rate: ~5M of top pair events in Run-I Main producon modes: σ pp →tt ≈ 200pb - gluon fusion gg →tt ( ) - quark-anquark annihilaon qq →tt

€ € €

~85% of σ ~15% of σ Relevant events to measure asymmetry

- The Top Charge Asymmetry at the LHC - 4 Top Quark Pair Charge Asymmetry

What is the Top Charge Asymmetry: Measure anisotropy in (an-)top producon wrt NO ASYMMETRY incoming (an-)quark direcon.

t q q

€ top direcons an-top direcons q q € ASYMMETRY €

t € C.M. reference frame € q q

€ N.B. requires asymmetric inial state (e.g. quark-anquark annihilaon€ ) €

- The Top Charge Asymmetry at the LHC - 5 Outline

• Movaon – the A FB puzzle

• The asymmetry at the LHC - A C

• Early measurements at the LHC: ATLAS lepton+jets 1.04 -1 at √s=7 TeV Eur.Phys.J. C72 (2012) 2039

• Boosng the charge asymmetry Phys.Le. B707 (2012) 92-98

• Charge asymmetry at ATLAS: lepton+jets 4.7 -1 at √s=7 TeV JHEP 02 (2014) 107

• A C at √s=14 TeV with a photon handle arxiv:1402.3598

- The Top Charge Asymmetry at the LHC - 6 Outline

• Movaon – the A FB puzzle

• The asymmetry at the LHC - A C

• Early measurements at the LHC: ATLAS lepton+jets 1.04 -1 at √s=7 TeV Eur.Phys.J. C72 (2012) 2039

• Boosng the charge asymmetry Phys.Le. B707 (2012) 92-98

• Charge asymmetry at ATLAS: lepton+jets 4.7 -1 at √s=7 TeV JHEP 02 (2014) 107

• A C at √s=14 TeV with a photon handle arxiv:1402.3598

- The Top Charge Asymmetry at the LHC - 7 AFB @ Tevatron

Afb of the Top Quark In 2011 both CDF and D0 collaboraons V. Ahrens et. al., July 2011 arXiv:1106.6051v1 (2011) reported a non-zero forward-backward (** submitted to a journal) W. Hollik and D. Pagani, asymmetry in top quark pair producon arXiv:1107.2606 (2011) (* preliminary) deﬁned as:

CDF LJ 0.158 ± 0.074 (±0.072 ± 0.017) -1 N(Δy > 0) − N(Δy < 0) ( 5.3 fb ) AFB = N(Δy > 0) + N(Δy < 0) CDF DIL* 0.420 ± 0.158 (±0.150 ± 0.050) -1 rapidity ( 5.1 fb ) with Δy = ytop – yan-top CDF combined* 0.201 ± 0.067 (±0.065 ± 0.018) (± stat ± syst) €

D0 LJ** 0.196 0.060 +0.018 • Triggered theorecal acvity for ± -0.026 -1 ( 5.4 fb ) precise SM predicons and BSM hypotheses (axigluons,Z’,..). 0 -0.4 -0.2 -0 0.2 0.4 0.6 0.8

Afb - The Top Charge Asymmetry at the LHC - 8 The SM charge asymmetry

1. 2. • SM top quark pair producon is charge asymmetric at NLO. ⊕ ⊕ • Main source of asymmetry is the QCD quark-anquark € annihilaon process. €

asymmetric QCD

The SM QCD asymmetry in originates from: qq →tt

1. Interference between tree and box diagram AFB>0

2. Interference between gluon ISR and FSR diagrams AFB<0 € - The Top Charge Asymmetry at the LHC - 9 BSM asymmetry

Z’ / W’ Axigluon

( ) d

€ (W’) ⊕

( ) d € t-channel: s-channel: exoc ﬂavor changing vector bosons interference between SM QCD and € exoc gluons with axial coupling

- The Top Charge Asymmetry at the LHC - 10 AFB @ Tevatron • inial state pp  forward-backward asymmetry • qq → dominant process (~85%)tt  small diluon -1 • updated results with full datasets (~10 ) sll report AFB consistently larger than SM predicon. € AFB 2.7σ from SM € t

q q € updated 9.7 -1 p p

€ € t € Lab reference frame € J.A. Aguilar-Saavedra et al. - arxiv:1302.6618 € - The Top Charge Asymmetry at the LHC - 11 Outline

• Movaon – the A FB puzzle

• The asymmetry at the LHC - A C

• Early measurements at the LHC: ATLAS lepton+jets 1.04 -1 at √s=7 TeV Eur.Phys.J. C72 (2012) 2039

• Boosng the charge asymmetry Phys.Le. B707 (2012) 92-98

• Charge asymmetry at ATLAS: lepton+jets 4.7 -1 at √s=7 TeV JHEP 02 (2014) 107

• A C at √s=14 TeV with a photon handle arxiv:1402.3598

- The Top Charge Asymmetry at the LHC - 12 Overview of the LHC

W.J. Srling, arxiv: 0901.0002 WJS 2010 1000 ratios of parton luminosities at 7 TeV LHC and Tevatron

100 gg • p-p collisions: charge symmetric inial state luminosity ratio 10 • dominated by gluon-gluon fusion: ~85% at √s=7,8 TeV Yqq >90% at √s=14 TeV MSTW2008NLO • average momentum imbalance 1 101 102 103 in qq events (an-quarks from sea)

MX (GeV)

- The Top Charge Asymmetry at the LHC - 13 € Asymmetry @ LHC • More diluted: qq →tt only ~15% at 8 TeV • (an)top is preferenally produced along the direcon of the incoming (an)quark. t € t

€ q q q q €

CM reference frame Lab reference frame € € € € • Direcon of the incoming quark not known in pp collisions - BUT - • Quarks more likely to be valence quarks ( larger fracon of momentum) • only sea an-quarks available • top quarks more forward than antops

- The Top Charge Asymmetry at the LHC - 14 Asymmetries Tevatron - collisions pp LHC - collisions pp

N(Δy > 0) − N(Δy < 0) N(Δ | y |> 0) − N(Δ | y |< 0) AFB = AC = €N (Δy > 0) + N(Δy < 0) € N(Δ | y |> 0) + N(Δ | y |< 0) with Δ|y| = |y | - |y | with Δy = ytop – yan-top top antop

€ €

ﬁgures from G.Rodrigo, arxiv:1207.0331

- The Top Charge Asymmetry at the LHC - 15 Outline

• Movaon – the A FB puzzle

• The asymmetry at the LHC - A C

• Early measurements at the LHC: ATLAS lepton+jets 1.04 -1 at √s=7 TeV Eur.Phys.J. C72 (2012) 2039

• Boosng the charge asymmetry Phys.Le. B707 (2012) 92-98

• Charge asymmetry at ATLAS: lepton+jets 4.7 -1 at √s=7 TeV JHEP 02 (2014) 107

• A C at √s=14 TeV with a photon handle arxiv:1402.3598

- The Top Charge Asymmetry at the LHC - 16 Charge asymmetry – l+jets

|y| 0.4 6 ATLAS ! + * 4 jets (* 1 b tag) /d m -1 data d 0.35 L dt = 1.04 fb m MC@NLO

1/ 0 0.3 ATLAS - l+jets Eur.Phys.J. C72 (2012) 2039 -1 0.25 √s = 7 TeV, 1.04

0.2 AC = -0.019 ± 0.028(stat.) ± 0.024(syst.) 0.15

0.1 Theory: AC = 0.0123 (5) W. Bernreuther et al., Phys. Rev. D 86 (2012) 034026 0.05

0 -3 -2 -1 0 1 2 3 6|y|

• First measurements at LHC7 compable with 0 asymmetry (and SM) • Large stascal and systemac uncertaines • The expected SM asymmetry is very small (~1%).

- The Top Charge Asymmetry at the LHC - 17 Experimental challenge

• Small fracon of quark-anquark annihilaon

small AC~1% • Direcon of the incoming quark not known in pp collisions

• Measured A C distorted by resoluon and acceptance. Need to extrapolate to parton-level asymmetry to compare with theory.

• Large systemac eﬀects from parton-level extrapolaon and from background modelling.

- The Top Charge Asymmetry at the LHC - 18 Outline

• Movaon – the A FB puzzle

• The asymmetry at the LHC - A C

• Early measurements at the LHC: ATLAS lepton+jets 1.04 -1 at √s=7 TeV Eur.Phys.J. C72 (2012) 2039

• Boosng the charge asymmetry Phys.Le. B707 (2012) 92-98

• Charge asymmetry at ATLAS: lepton+jets 4.7 -1 at √s=7 TeV JHEP 02 (2014) 107

• A C at √s=14 TeV with a photon handle arxiv:1402.3598

- The Top Charge Asymmetry at the LHC - 19 Boosted AC

• Expected A C is very small. Hard to measure. Phys.Le. B707 (2012) 92-98 • Fracon of qq →tt events increases with the velocity of the top quark pair along the beam axis €

“valence” quark tt large xq q q “sea” an-quark

small xq Lab reference frame € € € - The Top Charge Asymmetry at the LHC - 20 Outline

• Movaon – the A FB puzzle

• The asymmetry at the LHC - A C

• Early measurements at the LHC: ATLAS lepton+jets 1.04 -1 at √s=7 TeV Eur.Phys.J. C72 (2012) 2039

• Boosng the charge asymmetry Phys.Le. B707 (2012) 92-98

• Charge asymmetry at ATLAS: lepton+jets 4.7 -1 at √s=7 TeV JHEP 02 (2014) 107

• A C at √s=14 TeV with a photon handle arxiv:1402.3598

- The Top Charge Asymmetry at the LHC - 21 Overview of ATLAS Eﬃciently collected ~20 -1 of p-p collision data energy of jets, electrons

precision measurement of Muon detecon momenta of charged parcles in toroidal magnec ﬁeld

- The Top Charge Asymmetry at the LHC - 22 Outline

• Movaon – the A FB puzzle

• The asymmetry at the LHC - A C

• Early measurements at the LHC: ATLAS lepton+jets 1.04 -1 at √s=7 TeV Eur.Phys.J. C72 (2012) 2039

• Boosng the charge asymmetry Phys.Le. B707 (2012) 92-98

• Charge asymmetry at ATLAS: lepton+jets 4.7 -1 at √s=7 TeV JHEP 02 (2014) 107

• A C at √s=14 TeV with a photon handle arxiv:1402.3598

- The Top Charge Asymmetry at the LHC - 23 Measurements

Performed a complete set of measurements of the charge asymmetry:

• Inclusive measurement of A C, AC(βz,>0.6) and AC(m>600 GeV)

• Diﬀerenal measurements: the dependence of A C vs kinemacs of the top quark pair might provide useful informaon for BSM discriminaon/ understanding of the SM.

same as βz,

AC vs |y|: sensive to enhancement of asymmetry at high rapidity, due to increase of the fracon of qq →t events. t

AC vs m: expected diﬀerent behavior for diﬀerent BSM scenarios. Also with β >0.6 to enhance qq → fracon. tt €z,

AC vs pT,: more sensive to asymmetry from ISR/FSR interference.

- The Top Charge Asymmetry at the LHC - € 24 Analysis ﬂow

Selecon of semileptonic top pair events Background esmaon

Kinemac Unfolding to parton level reconstrucon • resoluon of the top pair: • acceptance • Δ|y|

• m • p T, • |y |, βz, Results

- The Top Charge Asymmetry at the LHC - 25 Event selecon semileptonic (lepton=μ,e) top pair decays: • large BR (~30%) • manageable background (W+jets,muljets) • use lepton charge to tag top/antop quark

Selecon:

• exactly 1 isolated lepton with p T >20 (e), 25 (μ) GeV • at least 4 jets with p T>25 GeV and |η|<2.5 • at least 1 b-tagged jet (eﬃciencies: 70% b-jets, 20% c-jets, <1% light jets) • addional cuts on leptonic W to reduce muljet background with fake leptons

- The Top Charge Asymmetry at the LHC - 26 Event yields

signal region signal region

• Less events in e+jets due to ghter requirements on leptonic W to reduce the larger muljets background • Normalizaon uncertaines are shown. • Overall good agreement of data with predicons

- The Top Charge Asymmetry at the LHC - 27 Kinemac reconstrucon Top-antop pair system fully reconstructed with kinemac likelihood ﬁt. Likelihood input: • 4-momenta of four jets • 4-momentum of the lepton • missing transverse momentum Constraints:

mt=172.5 GeV, Γt=1.5 GeV mW=80.4 GeV, ΓW=2.1 GeV

Breit-Wigner’s for top quarks and W bosons

energy transfer funcons

favor b-tagged jets in b-posions

- The Top Charge Asymmetry at the LHC - 28 Reconstructed quanes

Δ|y| = |ytop| - |yantop|

• Distorons from acceptance and resoluon. • Eﬃciency for correct sign of reconstructed Δ|y|: p~75% correct Δ|y| sign vs m  diluon D=2·p-1~0.5 of the parton level asymmetry

- The Top Charge Asymmetry at the LHC - 29 Unfolding

AC in simulaon (MC@NLO): reconstructed Δ|y|: (0.3 ± 0.1)% Esmates parton level AC spectra to compare directly with theory. parton-level Δ|y|: (0.519 ± 0.030)%

map of event migraons from truth bins to reco bins reconstructed Δ|y| distribuon R = M⋅ T parton-level Δ|y| distribuon • Fully Bayesian Unfolding - no explicit matrix inversion - prior choice determines bias - “automac” handling of systemacs and correlaons - The Top Charge Asymmetry at the LHC - 30 € Fully Bayesian Unfolding arXiv:1201.4612 hps://pypi.python.org/pypi/u

T: Δ|y| distribuon to D: Δ|y| distribuon measured esmate before resoluon in data distorted by resoluon and acceptance eﬀects. and acceptance.

L(D|T): likelihood of observing D given T. π(T): prior probability for T. Compares the eﬀect of acceptance and Encompass the prior knowledge or resoluon on a given T with what is assumpons on the distribuon T. measured in data (D).

The unfolding procedure esmates directly the probability density for AC at the parton level.

- The Top Charge Asymmetry at the LHC - 31 Results – Inclusive AC

• To date, most precise measurement for A C @ √s=7 TeV. • Measurement is limited by stascs.

• A C compable with 0 and SM predicons.

Theory predicons from W. Bernreuther and Z.-G. Si, Phys. Rev. D 86 (2012) 034026

Uncertaines are (stat.+syst.) • Stascal error is the dominant component.

- The Top Charge Asymmetry at the LHC - 32 Results – AC vs m C A 0.6 ` >0.6 z,tt ATLAS s= 7 TeV 0.5 Data -1 SM L dt = 4.7 fb 0.4 Axigluon m=300 GeV 0

0.3 Axigluon m=7000 GeV βz,>0.6 0.2

0.1

-0.1

0 100 200 300 400 500 600 700 800 900

mtt [GeV]

The measured AC spectra are compable with both • SM predicons

• Axigluon benchmarks with inclusive A C/AFB compable with current Tevatron and LHC results - The Top Charge Asymmetry at the LHC - 33 Results – Interpretaon 0.15 ATLAS G NON-comprehensive ! Wv set of BSM scenarios! 0.10 Models from: 4 PRD 84 115013, t arXiv:1107.0841 Axigluon models with opposite 4 0.05 1 q sign couplings with u and d

> 600 GeV) ATLAS quarks (not shown here) can be t t compable with both AC and AFB SM (m 0 (A /A cancellaon at the LHC). C u d A CDF -0.05

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 AFB (mtt > 450 GeV) • Tevatron results show some tension with SM predicons • LHC measurements are compable with the SM predicons.

• The W’ scenario is disfavored by the combinaon of A C and AFB measurements.

- The Top Charge Asymmetry at the LHC - 34 ATLAS - √s = 8 TeV

The ATLAS measurement at √s = 8 TeV will complete the AC picture at the LHC.

AC √s = 7 TeV √s = 8 TeV Theory 0.0123 ± 0.0005 0.0111 ± 0.0004 CMS 0.04 ± 0.015 (stat. + syst) 0.005 ± 0.009 (stat. + syst.) ATLAS ?

6x top quark pair events

σA~0.5% for inclusive AC Expected signiﬁcant reducon of stascal uncertainty wrt 7 TeV. Understanding and constraint of systemacs plays a signiﬁcant role.

- The Top Charge Asymmetry at the LHC - 35 Outline

• Movaon – the A FB puzzle

• The asymmetry at the LHC - A C

• Early measurements at the LHC: ATLAS lepton+jets 1.04 -1 at √s=7 TeV Eur.Phys.J. C72 (2012) 2039

• Boosng the charge asymmetry Phys.Le. B707 (2012) 92-98

• Charge asymmetry at ATLAS: lepton+jets 4.7 -1 at √s=7 TeV JHEP 02 (2014) 107

• A C at √s=14 TeV with a photon handle arxiv:1402.3598

- The Top Charge Asymmetry at the LHC - 36 AC with a photon handle

• At √s=14 TeV q q →tt events <10% sensivity for A washed out by C arxiv:1402.3598 gluon fusion events. € • Soluon: measure A C in events. tt γ x2 higher fracon than in qq tt ~same as Tevatron uu /dd for p (γ)>20 GeV € T /σ • Small cross-secon (2.73 pb) not an qq € € σ issue given the large amount of data € expected in Run-II (100-400 -1)

• Breaks potenal cancellaon between uu and process. dd

σdd/σuu - The Top Charge Asymmetry at the LHC - 37 € € Summary • Precision top-quark phenomenology provides indirect probes of NP beyond EW scale. Producon asymmetries of top quark pairs: sensive to broad class of SM extensions, experimentally robust against systemac eﬀects.

• First measurements at Tevatron indicated mild departure from SM predicons, raising signiﬁcant interest.

• A C @ LHC important to clarify experimental status: higher CM energy and luminosity

• ATLAS result most precise measurement at 7 TeV: - careful understanding of background modeling and associated systemacs, as well as unfolding requirements. - differenal measurements bring important addional informaon. - 8 TeV measurement underway will represent significant step forward in precision due to larger stascs and further experimental refinements.

• Measurement at 14 TeV will be challenging due to further wash out of asymmetry from increased gg fracon. Possible soluons: - increase using kinemacs (already exercised in 7 TeV measurements) qq - exploit other producon modes, e.g. tt γ - The Top Charge Asymmetry at the LHC - 38

€ € - Backup -

- The Top Charge Asymmetry at the LHC - 39 Signiﬁcance of boosted AC

• Signiﬁcant improvement in sensivity for systemacs limited results stat. only syst 1% syst 2%

-1 Int. luminosity: 10 @ √s=7 TeV Red: AC=2% Blue: AC=4% Green: AC=6%

- The Top Charge Asymmetry at the LHC - 40 Boosted AC - m

At very high β (~0.9) the m distribuon is distorted, thus introducing model dependence.

- The Top Charge Asymmetry at the LHC - 41 Boosted AC

• Cung on β improves model discriminaon. Gμ: heavy axigluon, M=7 TeV P3: light axigluon, M=850 GeV

no cut β>0.6

Int. luminosity: 10 -1 @ √s=7 TeV, 1% systemac uncertainty

- The Top Charge Asymmetry at the LHC - 42 Backgrounds

W+jets Muljets • Largest background (~15%) • Charge symmetric • Residual “top” charge • Huge x-sec but ny acceptance asymmetry from W+/W-≠1 (~5% background in l+jets selecon) • Large uncertaines on • Hard to model fake lepton rates predicons for overall use of simulaon not praccal normalizaon and ﬂavor • Esmate rate and shape from data composion

Other backgrounds (<5%) from simulaon: Z+jets, single top, diboson

- The Top Charge Asymmetry at the LHC - 43 W+jets esmaon • Shapes from simulaon

• Normalizaon extracted from data exploing W charge asymmetry

rMC +1 + − NW = (NW + + NW − ) = ⋅ (D − D ) rMC −1

+ - rMC = W /W rao from simulaon ATLAS D+(-) = # of selected posive(negave) Internal € lepton events in data

• Simultaneous ﬁt of normalizaon and ﬂavor composion (W+bb/cc,W+c,W+light)

• Modeling is cross-checked in W+jets enriched control region (=0 b-jets) - The Top Charge Asymmetry at the LHC - 44 Muljets esmaon

Miss • Fully data-driven esmates for shapes and rates ET in >=4 jets, pre-tag • Fake lepton-enriched loose selecon

• Solve system of equaons

fakes in loose loose loose N = Nreal + N fake signal region tight loose loose N = εreal ⋅ Nreal +ε fake ⋅ N fake

- Nght = # of events in ght selecon € - Nloose = # of events in loose selecon

- ε real = eﬃciency of ght selecon on real leptons - ε fake = eﬃciency of ght selecon on fake leptons

- The Top Charge Asymmetry at the LHC - 45 FBU - Likelihood

migraon matrix M

- The Top Charge Asymmetry at the LHC - 46 FBU – p(AC|D)

The posterior probability for AC is obtained from p(Δ|y|).

0.020 Mean=0.027

RMS=0.010 0.015 p(AC) p(Δ|y|)

0.010 Posterior probability

0.005

0.000 -0.02 0.00 0.02 0.04 0.06

Ac(T)

- The Top Charge Asymmetry at the LHC - 47 FBU - Background

The background predicon is included in the likelihood deﬁnion NO background subtracon from distribuon of data before unfolding.

- The Top Charge Asymmetry at the LHC - 48 FBU - Marginalizaon

• Bayesian inference framework  marginalizaon of systemacs • The posterior probability is integrated over the nuisance parameters.

nuisance parameters

• In √s=7 TeV l+jets results the integral is approximated with a weighted sum of nominal,+1σ,-1σ posterior probability distribuons.

- The Top Charge Asymmetry at the LHC - 49 Systemacs √s=7 TeV

Average diﬀerence of the mean of p(AC) for +1σ/-1σ variaon of the source of uncertainty.

- The Top Charge Asymmetry at the LHC - 50 FBU – systemacs √s=7 TeV

- The Top Charge Asymmetry at the LHC - 51 Results – AC vs m

no βz, cut βz,>0.6 0.25 C C A A 0.6 ` >0.6 Data ATLAS ATLAS 0.2 z,tt s= 7 TeV Data s= 7 TeV SM 0.5 -1 -1 0.15 L dt = 4.7 fb SM L dt = 4.7 fb Axigluon m=300 GeV 0 0.4 Axigluon m=300 GeV 0 Axigluon m=7000 GeV 0.1 0.3 Axigluon m=7000 GeV

0.05 0.2

0.1 0 0 -0.05 -0.1 N.B. wider y-axis range -0.1 0 100 200 300 400 500 600 700 800 900 0 100 200 300 400 500 600 700 800 900

mtt [GeV] mtt [GeV]

The measured AC(m) spectrum is compable with both • SM predicons

• Axigluon benchmarks with inclusive A C compable with current Tevatron and LHC results

- The Top Charge Asymmetry at the LHC - 52 Results – AC vs |y|,pT,

AC vs |y| AC vs pT, 0.25 0.25 C C A A Data ATLAS ATLAS 0.2 0.2 Data s= 7 TeV s= 7 TeV SM SM -1 -1 0.15 L dt = 4.7 fb 0.15 L dt = 4.7 fb Axigluon m=300 GeV 0 0

0.1 Axigluon m=7000 GeV 0.1

0.05 0.05

0 0

-0.05 -0.05

-0.1 -0.1 0 0.2 0.4 0.6 0.8 1 0 10 20 30 40 50 60 70 80 90 100 |y | p [GeV] tt T,tt βz,≈0.6

• Clear enhancement of A C vs |y| (same as βz,) • Higher precision at high |y | due to beer sign(Δ|y|) reconstrucon • Large uncertaines in A C vs pT, due to migraons across pT, bins

- The Top Charge Asymmetry at the LHC - 53 Results – Interpretaon 0.15 ATLAS G ! Wv 0.10 Models from: 4 PRD 84 115013, t arXiv:1107.0841

4 0.05 1 q

> 600 GeV) ATLAS t t

(m 0 C A CDF -0.05

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 AFB (mtt > 450 GeV) • Tevatron results show some tension with SM predicons • LHC measurements are compable with the SM predicons.

• The W’ scenario is disfavored by the combinaon of A C and AFB measurements.

- The Top Charge Asymmetry at the LHC - 54 AC with a photon handle

Full 2A7 calculation 3.5 2A7 calculation w/o radiative top decay

[fb / GeV] preselection cuts

m 3 d dm + 6R cuts 2.5 + mass cuts

1.5

0.5

0 0 50 100 150 200 250 300 350 400 450 500 m(a,b,q,q) [GeV]

- The Top Charge Asymmetry at the LHC - 55 AC with a photon handle

- The Top Charge Asymmetry at the LHC - 56 AC relaves

Other important aspects to invesgate at the LHC: Precision measurements - lepton asymmetry: sensive to top polarizaon

- collider independent asymmetries A u/Ad Phys.Rev.Le. 109 (2012) 211804 Direct searches t Run-II dataset will improve direct searches for asymmetry-related NP: A - mulple top quarks producon (axigluon) t - same sign top quarks producon (Z’) € - top and boom quark pairs associated t producon (axigluon) A - ... € t - The Top Charge Asymmetry at the LHC - 57 €

€