Top Quark and Exotic Models: Theoretical Overviewfaculty.pku.edu.cn/_tsf/00/0A/6jQRbmqmqEre.pdf ·...

Top Quark and Exotic Models: !Theoretical Overview

Qing-Hong Cao Peking University

7th International Workshop on Top Quark PhysicsOpt 2014

Oct. 02, 2014

TOP @ inSPIRE

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Two anomalies

2I will focus on the second anomaly and NP explanations

Top Quark and New Physics

Strongly Interacting

Higgs (125GeV)

Effective Field

Theory

Experimental Data

What could !we see?

What should we see?

Natural NP models always have non-trial couplings between top quark and

NP particles

SUSY, LH, Composite, RS, TC…

Weakly Interacting

3

Top quark as a probe of new physics

Gluino

Exotic Colored States

4th Gen

Vector Quark

FCNC

Charged  Higgs

AFB

Extra Gauge Bosons

New Heavy Quarks

CPHeavy Quark Production via pQCD

TopColor Sextet

It appears often in the decay of NP resonances

4

Vector QuarksCommon in many NP models, Economics for model building

Mass Mixing and Heavy Quark Couplings to Higgs

!"#$%&'()(*+%,-.(/%01+23%4(+*5'6%7897:%;1($*1)1-.?%$-.1*+(+*5'%+*1%D"''$JE1%

BG,7/%'$-KE1.%

456$25,(

(

(

(

(

(

7&"+6$25,(

(

BC%L(5+@+% MNON%L(5+@+% PQDE$

Vector QuarksT ! W+b/Zt/Ht

B ! W+t/Zb/HbY ! W+tX ! W�b

bb̄, ⌧+⌧�, V V ⇤

``, jj

`⌫, jj W

Z

h

Y

T

B

X

t

b

b`⌫, bjj

Very Rich Collider Signatures6

Extra Color Gauge BosonSU(3)1 ⇥ SU(3)2 ! SU(3)C

SU(3)1 SU(3)2Model

qL tR bR (t, b)L qR

qLtR bR (t, b)LqR

New Axigluon

Classic Axigluon

Topgluon qL (t, b)L tR bRqR

q=u,d,c,s

dijet, AFB(t)

dijet, AFB(t)

dijet, FCNC

Frampton, Glashow (1987)

Frampton, Shu, Wang (2010)

Hill (1991)

+ Extra color scalars 7

Extra Weak Boson and Quarks

SMqL

uRdR

Heavy QuarkQL

QR

H

SU(3)C ⇥ SU(2)1 ⇥ SU(2)2 ⇥ U(1)X

SU(3)C ⇥ SU(2)L⇥U(1)L ⇥ U(1)X

SU(3)C ⇥ SU(3)W ⇥ U(1)XG(331) Model

U’(1) model Z-prime

G(221) Model

�

8

Extra Weak Gauge BosonsSU(2)1 SU(2)2 U(1)X

U(1)Y

U(1)em

⊗ ⊗SU(2)1 SU(2)2 U(1)X

SU(2)L

U(1)em

⊗ ⊗(a) (b)

U(1)Y SU(2)L

LRD (LRT): left-right doublet (triplet) model

LPD (LRT): Leptophobic doublet (triplet) model

HPD (LRT): Hadrophobic doublet (triplet) model

FPD (LRT): Fermio-phobic doublet (triplet) model

SQD: Sequential W’ with doublet Higgs

NUD: Non-universal doublet model

UUD: Un-unified doublet model

QHC, Li, Yu, Yuan

1205.3769

ken, Schmitz, Yu, Yuan

1003.3482

221 Model:SU(2)1 ⌦ SU(2)2 ⌦ U(1)X

9

Extra Weak Gauge Bosons221 Model:

q

q̄′

W ′

t

b̄

q

q̄

Z ′

t

t̄

L = q̄�µ(gZ0L PL + gZ0

R PR)q Z0µ ++q̄�

µ(gW0

L PL + gW 0

R PR)q0 W 0+µ + h.c.

TABLE I: Couplings of a W ′ to tb and a Z ′ to tt̄ for the sequential SM-like W ′/Z ′ (SSM)

model, the left-right symmetric model (LRM), and the top-flavor model, where sw (cw, tw) =

sin θw (cos θw, tan θw), θw is the weak mixing angle, g2 = e/sw is the weak coupling, αLR ≃ 1.6,

and sin φ̃ is taken to be 1/√2.

W ′tb Z ′tt̄

SSMg2√2b̄γµPLtW

′µ g26cw

t̄γµ((−3 + 4s2w)PL + 4s2wPR)tZ ′µ

LRMg2√2b̄γµPRtW

′µ g2tw6

t̄γµ(1

αLRPL + (

1

αLR− 3αLR)PR)tZ ′µ

Top-Flavorg2 sin φ̃√

2b̄γµPLtW

′µ g2 sin φ̃√2

t̄γµPLtZ′µ

• left-right symmetric model (LRM) [29]: Here, we consider a SU(2)L × SU(2)R ×

U(1)B−L model. The W ′ couplings to SM quarks are purely right-handed while the

Z ′ couplings are dominantly right-handed.

Table I is a summary of the couplings of a W ′ and a Z ′ to SM third generation quarks in

these models. The couplings to the quarks of first two generations are the same, except that

one should replace sin φ̃ by cos φ̃ in the top-flavor model.

A. Bounds on masses and couplings

The masses and couplings of Z ′ and W ′ bosons are bounded by various low energy

measurements (mainly via the four-fermion operators induced by exchanges of new heavy

gauge bosons) such as the precision measurements at the Z-pole at LEP-I [30], the W -

boson mass [30], the forward-backward asymmetry in bb̄ production at LEP-II [30], νe

scattering [31], atomic parity violation [32–34], Moller scattering [35], and so forth. The

bounds are severe when new gauge bosons couple to leptons directly, but they can be relaxed

for a leptophobic model, as analyzed in Ref. [22].

Tevatron data place a lower bound about 1.1 TeV on the mass of a W ′ [36] and about

1.07 TeV for a Z ′ [37], based on the charged lepton plus missing energy (ℓ±E̸T ) and µ+µ−

final states, respectively, with the assumption that the couplings between the W ′/Z ′ and the

SM fermions are the same as those in the SM. Searches for the W ′ and Z ′ at the Tevatron in

dijet events yield lower bounds on mW ′ and mZ′ , assuming SM couplings, of 840 GeV and

6

SU(2)1 ⌦ SU(2)2 ⌦ U(1)X

10

Extra Weak Gauge Bosons

0

@udD

1

A

0

@csS

1

A

0

@b�tT

1

A

3 3 3

SU(3)⇥ U(1)X �! SU(2)L ⇥ U(1)Y �! U(1)emH1 H2

Diaz, Martinez, Ochoa, hep-ph/0309280 Barreto, Coutinho, Sa Borges, 1103.1266 Buras, Fazio, Girrbach, Carlucci, 1211.1237

331 Model:

Z-prime: flavor changing coupling to u- and top-quark also the chiral coupling to light-quarks and top-quarks

SU(3)C ⌦ SU(3)W ⌦ U(1)X

11

Exotic Colored Scalars/VectorsEffective Lagrangian:

Atag, !Cakir, !

Sultansoy, !(1999)

Q = QL

U = uRD = dR

Arnold,!Pospelov,!

Trott,!Wise!

(2009)

12

Top Quark and New Physics

ProductionProton Proton

Others

t

Rare Decay or Light

Resonance not covered in this talk

tt

t

….

T,B,G0,W 0, Z 0,�0,�+,�8,�3,�6, DM 13

Single Top Quark Production


Others

t

….

14

Single Top Quark Productionb

g

t

WtW

u

d t

b

s-channel

Wu d

b tt-channel

W

u

d t

bW’ b

g

t

W

b’

FCNC Excited

quark

H+S6

New

resonance

Q2W > 0 Q2W < 0 Q

2W = m

2W

Drueke, Schwienhorst, Vignaroli, Walker, Yu, 1409.7607

u u

u/c tZ’ S0

QHC, Wudka, Yuan, 0704.2809Tait, Yuan, hep-ph/0007298

15

Single Top Quark Production(s-channel resonance and t-channel FCNC)

Drueke, Schwienhorst, Vignaroli Walker, Yu, 1409.7607

Tait, Yuan, hep-ph/0007298 Gogoladze et al, 1001.5260 16

Single Top Quark Production(s-channel excitation quark)

b

g

t

W

b’ q

g

t

Z

Q’q

g

t

g

Q’

Nutter, Schwienhorst, Walker, Yu, 1207.5179

L = gsB̄0�µB0 +gs�

2⇤Gµ⌫ b̄�

µ⌫�bLPL +

bRPR

�B0 + h.c.

L = gWp2W+µ t̄�

µ(fLPL + fRPR)B0 + h.c.L = gWp

2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�


2W+µ t̄�

µ(fLPL + fRPR)B0 + h.c.

17

Single Heavy Quark Productionq q0

bT

b

W

W⌫

`+

Little Higgs Perelstein, Peskin, Pierce hep-ph/0310039

Composite Higgs Li, Liu, Shu, 1306.5841

q

b

q0

Th

bb̄

t

Boosted jet-substructure

Reuter, Tonini, 1409.6962

18

Mono Top Quark Production(R-parity violating SUSY inspired)

Andrea, Fuks, Maltoni, 1106.6199 Wang, Li, Shao, Zhang, 1109.5963

W

d̄i

d̄j

φ

χ

tb

j

j

d̄i

d̄j

φ

χ

tb

v

l

W

FIG. 7: Feynman diagrams for the monotop production.

which are shown in Fig. 7. The symbol b and j denote a b-tagged jet and light quark

or gluon jet, respectively, and l refers to the first two generation charged leptons, i.e., e

and µ. We define the process with top hadronic decay as hadronic mode, while the one

with top semileptonic decay as semileptonic mode. The hadronic mode suffers from fewer

backgrounds in the SM than the semileptonic mode because of the smaller phase space due

to more particles in the final states. This mode has been studied in Ref. [11] where they

assume the branching fraction R(φ → tχ̄) equal to one. However, this assumption is over

optimistic. From Eq. (26) we get the branching fraction R(φ → tχ̄),

R(φ → tχ̄) =Γφ→tχ̄

Γφ→tχ̄ + Γφ→d̄s̄=

1

1 + z, (29)

with

z =8(λ12S )

2

|a3S|2m4φ

(m2φ −m2t −m2χ)λ1/2(m2φ, m2t , m2χ). (30)

Here we assume that the decay widths Γφ→uχ̄ = Γφ→cχ̄ = 0. In the case of λ12S = a3S =

0.2, mt = 173.1 GeV, mφ = 500 GeV and mχ = 50 GeV, we find Γφ→tχ̄ = 0.300 GeV,

Γφ→d̄s̄ = 3.183 GeV, and the branching fraction of φ → tχ̄ is just about 0.1. So, in this

work, we take into account the effect of both φ decay channels and below we will discuss

further the hadronic and leptonic modes in detail.

Before discussing the signal and backgrounds in detail, we first give some comments on

the parameter mχ. In the SUSY model, without the assumption of gaugino mass unification,

there is no general mass limit from e+e− colliders for the lightest neutralino [20]. The indirect

constraints from (g − 2)µ, b → sγ and B → µ+µ− show that the lightest neutralino mass

can be as low as about 6 GeV [36]. In our case, we choose the default value of mχ = 50 GeV

and discuss the effect on the discovery significance when varying mχ in the range 5 − 100

11

2

S

d̄j

d̄i

t

χ

t

g

ui

t

V

FIG. 1: Representative Feynman diagrams leading to mono-top signatures, through the resonant exchange of a coloredscalar field S (left) and via a flavor-changing interaction witha vector field V (right). In these two examples, the missingenergy is carried by the V and χ particles. More diagramswith, for example, t-channel and s-channel exchanges for thetwo type of processes respectively, are possible.

SU(3)c. As an example, consider the s-channel resonantcase

d̄id̄j → S or V → tχ ,

where dk denotes a down-type quark of generation k.Such processes occur in R-parity-violating SUSY [5]where, similarly to the case discussed in Ref. [6], the in-termediate particle is a (possibly on shell) squark andχ the lightest neutralino (d̄s̄ → ũi → tχ̃01, where ũi areany of the up squarks), or in SU(5) theories where a vec-tor leptoquark V decays into a top quark and a neutrino(d̄d̄ → V → tν̄). The key difference between these twoexamples is the mass of the invisible fermionic state in-ducing different transverse-momentum (pT ) spectrum forthe top quark. In the limit of a very heavy resonance,monotops can be seen as being produced through abaryon number-violating effective interaction (d̄s̄ → tχ̄),after having included the possible t- and u-channel ex-changes of a heavy field [7, 8]. Let us note that thefermionic particle could also be a Rarita-Schwinger field,as in SUSY theories containing a spin-3/2 gravitino field,or a multiparticle state (with a global half-integer spin),as in hylogenesis scenarios for dark matter [9].In the second class of models, the top quark is pro-

duced in association with a neutral bosonic state, eitherlong-lived or decaying invisibly, from quark-gluon initialstates undergoing a flavor-changing interaction, as dis-cussed, e.g., in Ref. [10]. Missing energy consists eitherin a two-fermion continuous state, as in R-parity conserv-ing SUSY [11], or in a spin-0 (S), spin-1 (V ) or spin-2(G) particle,

ug → ũiχ̃01 → tχ̃01χ̃01 , ug → tS , tV or tG .

EFFECTIVE THEORY FOR MONOTOPS

The top quark kinematic distributions depend bothon the partonic initial state and on the nature of theundetected recoiling object (scalar, massive or massless

fermion, vector or tensor), as well as on the possiblepresence of an intermediate resonant state. This sug-gests a model-independent analysis where we account forall cases within a single simplified theory, in the samespirit as Ref. [12]. Assuming QCD interactions to beflavor-conserving, as in the SM, the flavor-changing neu-tral interactions are coming from the weak sector. Wedenote by φ, χ and V the possible scalar, fermionic andvectorial missing energy particles, respectively and by ϕand X scalar and vector fields lying in the fundamen-tal representation of SU(3)c which could lead to res-onant monotop production.1 In addition, we obtain asimplified modeling of four-fermion interactions throughpossible s, t, u exchanges of heavy scalar fields ϕ and ϕ̃.The corresponding effective Lagrangian in terms of masseigenstates reads

L = LSM

+ φū[

a0FC+b0

FCγ5]

u+Vµū[

a1FCγµ+b1FCγ

µγ5]

u

+ϵijkϕid̄cj

[

aqSR+bqSRγ5

]

dk+ϕiūi[

a1/2SR+b1/2SRγ5

]

χ

+ϵijkϕ̃id̄cj

[

ãqSR+ b̃qSRγ5

]

uk+ϕ̃id̄i[

ã1/2SR+ b̃1/2SRγ5

]

χ

+ ϵijkXµ,i d̄cj

[

aqV Rγµ + bqV Rγ

µγ5]

dk

+Xµ,i ūi[

a1/2V Rγµ + b1/2V Rγ

µγ5]

χ+ h.c.,

(1)

where the superscript c stands for charge conjugation,i, j, k are color indices in the fundamental representationand flavor indices are understood. The matrices (in fla-

vor space) a{0,1}FC and b{0,1}FC contain quark interactions

with the bosonic missing-energy particles φ and V , while

a1/2{S,V }R and b1/2{S,V }R are the interactions between up-type

quarks, the invisible fermion χ and the new colored statesϕ and X . The latter also couple to down-type quarkswith a strength given by aq{S,V }R and b

q{S,V }R. Because

of the symmetry properties of the ϵijk tensor, identicalquark couplings to the scalar field ϕ vanish and so dotheir axial couplings to the vector field X . In the caseof four-fermion interactions, we also need to introduce

additional ãqSR, b̃qSR, ã

1/2SR and b̃

1/2SR interaction matrices,

assuming heavy masses for the ϕ and ϕ̃ fields.

1 For simplicity, we neglect spin-2 gravitons, as their flavor-changing couplings are loop-induced and thus very small [13],as well as any of their excitations, which, even if they have, onthe one hand, typically flavor-violating couplings at tree level, donot lead, on the other hand, to a missing energy signature. Onthe same footing, we do not consider spin-3/2 fields since theircouplings are, at least in SUSY theories, in general suppressedby the SUSY-breaking scale.

5

10

15

20

2530

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.140.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

ΛS12

a S3

FIG. 11: The significance in the hadronic mode at the LHC (√s = 7 TeV) with an integrated

luminosity of 1 fb−1 versus the parameters λ12S and a3S , assumingmφ = 500 GeV and mχ = 50 GeV.

LHC 7 TeV S! B "5

1 fb#1

10 fb#1

600 800 1000 1200 1400 1600 1800 20000

1

2

3

4

5

mΦ!GeV

ΛS

FIG. 12: The 5σ discovery limits of mφ and λS(= λ12S = a3S) in the hadronic mode at the LHC

(√s = 7 TeV). Either band consists of twenty solid lines from the bottom up corresponding to the

value of mχ varying from 5 GeV to 100 GeV with a step of 5 GeV.

B. Semileptonic mode

For the semileptonic mode, the dominant backgrounds are pp → W (lν)j with the jet

misidentified as a b-jet and single top production with semileptonic top quark decay. The

Wj background is very large because there are only two final-state particles, compared with

17

see Theveneaux-Pelzer’s poster

19

Top-Antitop or Top-Top ! Quark Pair Production


Others

t

t

20

Top-quark F-B asymmetry in the SM(A charge asymmetry arises at NLO)

VOLUME 81, NUMBER 1 P HY S I CA L REV I EW LE T T ER S 6 JULY 1998

Charge Asymmetry in Hadroproduction of Heavy Quarks

J. H. Kühn and G. RodrigoInstitut für Theoretische Teilchenphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany

(Received 12 February 1998; revised manuscript received 17 April 1998)A sizable difference in the differential production cross section of top and antitop quarks, respectively,

is predicted for hadronically produced heavy quarks. It is of order as

and arises from the interferencebetween charge odd and even amplitudes, respectively. For the Fermilab Tevatron it amounts to upto 15% for the differential distribution in suitable chosen kinematical regions. The resulting integratedforward-backward asymmetry of 4% 5% could be measured in the next round of experiments. Atthe CERN Large Hadron Collider the asymmetry can be studied by selecting appropriately chosenkinematical regions. [S0031-9007(98)06481-3]

PACS numbers: 12.38.Qk, 12.38.Bx, 13.87.Ce, 14.65.Ha

Top quark production at hadron colliders has becomeone of the central issues of theoretical [1] and experimen-tal [2] research. The investigation and understanding ofthe production mechanism is crucial for the determina-tion of the top quark couplings, its mass, and the searchfor new physics involving the top system. A lot of efforthas been invested in the prediction of the total cross sec-tion and, more recently, of inclusive transverse momen-tum distributions [1].In this Letter we will point to a different aspect of the

hadronic production process, which can be studied witha fairly modest sample of quarks. Top quarks producedthrough light quark-antiquark annihilation will exhibita sizable charge asymmetry—an excess of top versusantitop quarks in specific kinematic regions—inducedthrough the interference of the final state with initial-state radiation [Figs. 1(a) and 1(b)] and the interferenceof the box with the lowest-order diagram [Figs. 1(c)and 1(d)]. The asymmetry is thus of order a

s

relativeto the dominant production process. In suitable chosenkinematical regions it reaches up to 15%, the integratedforward-backward asymmetry amounts to 4%–5%. Topquarks are tagged through their decay t ! b W1 and canthus be distinguished experimentally from antitop quarksthrough the sign of the lepton in the semileptonic modeand eventually also through the b tag. A sample of 100to 200 tagged top quarks should, in fact, be sufficient fora first indication of the effect.Top production at the Fermilab Tevatron is dominated

by quark-antiquark annihilation, hence the charge asym-metry will be reflected not only in the partonic rest framebut also in the center of mass system of proton and an-tiproton. The situation is more intricate for proton-protoncollisions at the CERN Large Hadron Collider (LHC),where no preferred direction is at hand in the laboratoryframe. Nevertheless, it is also in this case possible topick kinematical configurations which allow the study ofthe charge asymmetry.The charge asymmetry has also been investigated in

[3] for a top mass of 45 GeV. There, however, only

the contribution from real gluon emission was consideredrequiring the introduction of a physical cutoff on thegluon energy and rapidity to avoid infrared and collinearsingularities. Experimentally, however, only inclusivetop-antitop production has been studied to date, and theseparation of an additional soft gluon will in general bedifficult. In this Letter, we will therefore include virtualcorrections and consider inclusive distributions only. Wewill see below that the sign of the asymmetry for inclusiveproduction is opposite to the one given for the t¯tg processin [3]. The charge asymmetry of heavy flavor productionin quark-antiquark annihilation to bottom quarks was alsodiscussed in [4–6] where its contribution to the forward-backward asymmetry in proton-antiproton collisions wasshown to be very small. In addition, there is also a slightdifference between the distribution of top and antitopquarks in the reaction gq ! t¯tq. At the Tevatron itscontribution is below 1024. (This effect should not beconfused with the large asymmetry in the top quarks’angular or rapidity distribution in this reaction which is atrivial consequence of the asymmetric partonic initial stateand vanishes after summing over the incoming partonbeams.)

(c) (d)

(b)(a)

q

q

Q

Q

FIG. 1. Origin of the QCD charge asymmetry in hadroproduc-tion of heavy quarks: interference of final-state (a) with initial-state (b) gluon bremsstrahlung plus interference of the box (c)with the Born diagram (d).

0031-9007y98y81(1)y49(4)$15.00 © 1998 The American Physical Society 49

t̄

t

P (q) P̄ (q̄)

21

Kuhn, Rodrigo

hep-ph/9802268

SM NLO QCD

AtFB = 5%

Brown, Ellis, Rainwater

hep-ph/0509267

Collider simulation of tt+0(1)j

Measuring AFB is

very challenging

Almeida, Sterman, Vogalsang

0805.1885

NLL Threshold resum.

Asymmetry is robust

Dittmaier, Uwer, Weinzierl

hep-ph/0703120

NLO QCD corr. to ttbar+j

Ahrens, Ferroglia, Neubert,

Pecjak, Li Lin Yang,

1003.5827

SCET NNLL

1998 2005 2007 2008 2010

Melnikov, Schulze

1004.3284

Confirm Dittmaier et al

D0 (1.9 fb-1)

0712.0851

uncorrected

2011

AFB = [12± 8± 1]%

CDF (1.9 fb-1)

0806.2472

!Consistent with SMAFB = [24± 14]%

D0 (5.4fb-1)

1107.4995

CDF (5.3fb-1)

1101.0034

AFB = 0.475± 0.114mtt̄ � 450 GeVfor

AtFB = [19.6± 6.5]%A`FB = [15.2± 4.0]%

SM t

heo.

Pre

dict

ion

Exp. Measurements

Timeline of top-quark AFB

22

Top Quark AFB and NPs-channel t-channel (Flavor changing)

Effective theory q

q

t

t

q

q

q

q

t

t

t

t

Z 0,W 0,�

�6,�3̄

q

q

t

t

q

q

t

t

g

G0

SM

23

Timeline of and NP modelsAtFB

2007, 2008 2010, 20112009

Antunan, Kuhn, Rodrigo

Axigluon

0709.1652

Frampton, Shu, Wang

Axigluon

0911.2955

Shu, Tait, Wang

Color Sextet/triplet scalar

0911.3237

Arhrib, Benbrik, Chen

Color Sextet/triplet scalar

0911.4875

Djouadi, Moreau, Richard, singh

KK Gluon

0906.0604

Jung, Murayama, Pierce, Wells

FCNC Z-prime

0907.4112

Cheung, Keung, Yuan

FC W-prime

0908.2589

J. Cao, Heng, Wu, Yang

-SUSY and TC2

0912.14476R

QHC et al

Effective coupling

(G’, Z’, W’, H0,H+)

1003.3461

Jung, Ko, Lee, Nam

EFT

0912.1105

Ferrario, Rodrigo

Axigluon

0809.3353

Ferrario, Rodrigo

chiral G’

0906.5541

Xiao, Wang, Zhu,

NLO QCD to Z-prime

1006.2510

Shao, Li, et al

NLO QCD to EFT

1107.4012Yan, Wang, Shao, Li

NLO QCD to W-prime

1110.6684

s-channel

t-channel

EFT

NLO

QC

D

Dorsner, Fajfer,Kamenik, Kosnik,

Colored scalar

0912.0972

Bauer et al,

NLO RS

1008.0742

Chivukula, Simmons, Yuan

Axigluon

1007.0260

Aguilar-Saavedra

Perez-Victoria

1103.2765

Degrande, Gerard,

Grojean, Maltoni,

Servant, 1010.6304

24

See review: kamenik, Shu, Zupan, 1107.5257 Aguilar-Saavedra, Amidei, Juste, Perez-Victoria,1406.1798 25

1) Same Sign Top Quark Pairs-channel t-channel

Mohapatra, Okada, Hai-Bo Yu, 0709.1486 Berger, QHC, Chen, Shaughnessy, Zhang, 1005.2622, 1009.5379 Aguilar-Saavedra, Perez-Victoria, 1104.1385 Atwood, Gupta, Soni, 1301.2250

Maximal flavor violation Bar-Shalom, Rajaraman, Whiteson, Yu, 0803.3795FCNC effective coupling see Goldouzian’s talk, 1408.0493

3⌦ 3 = 6� 3̄u

u

tL

tL

(tR)

(tR)�(3,1)6,3

u

uZ 0

tR

tR

Flavor changing Z-prime Berger, QHC, Chen, Li, Zhang 1101.5625

�

26

2) Top Quark Pair Plus one Jet(Flavor Changing Interaction)

Gresham, Kim, Zurek, 1102.0018

g

u

t

u(t)

t̄(ū)

Z 0

g t

d W0

t̄

d

Berger, QHC, Chen, Li, Zhang, 1101.5625

g

u

t̄

t

u

�6,3

27

3) Top Quark Pair Plus One Jet(Third Generation Favored W-prime and Z-prime)

Topflavor Seesaw Model He, Tait, Yuan (2000), Wang, Du, He (2013)

g

t

Z 0

t̄

g t

W 0t̄

bb

Berger, Cao, Yu, Yuan, 1108.3613

b

b

28

4) Top Quark Pair Plus One Jet(Charged Higgs Boson)

b

g

t

t̄

b

H�

X-section is large for large tanb in MSSM or Type II 2HDB.

X-section depends on mH and tanb

Top-quark polarization depends on tanb

βtan0 5 10 15 20 25 30 35 40

decay

D

-1

-0.5

0

0.5

1

decayDFB2A

=400GeV-H=14TeV, Ms,-tH

(a)

βtan0 5 10 15 20 25 30 35 40

decay

D-1

-0.5

0

0.5

1

decayDFB2A

=400GeV-H=14TeV, Ms(b)

FIG. 12: (a) The degree of polarization of the antitop quark as a function of tan β of the tH−

signal event and (b) of all the signal and background processes with mH± = 400 GeV. The solid

black curve shows the degree of polarization defined in Eq. (37); the dashed red curve shows 2AFB.

The green band in (b) represents only the statistical uncertainties.

tan β has been considered very hard to measure. Figure 12 shows that the Ddecay varies

rapidly in the region of tan β = 5 ∼ 10. This feature enables us to determine tan β using

top polarization. However, the degree of polarization cannot be used to determine the value

of tan β in the large tanβ region as the degree of polarization approaches -1. Including the

t̄H+ signal and the two SM backgrounds inevitably reduces the degree of polarization, as

depicted in Fig. 12(b). The green band [cf. Eq. (39)] shows the statistical uncertainties

derived from all the signal and background events after all the kinematic cuts and event

reconstructions.

V. CONCLUSION AND DISCUSSION

The charged Higgs boson, an undoubted signal of new physics, appears in many new

physics models. In the type-II two-Higgs-doublet model the chirality structure of the cou-

pling of charged Higgs boson to the top and bottom quarks is very sensitive to the value

of tan β. As the polarization of the top quark can be measured experimentally from the

top quark decay products, one could make use of the top quark polarization to determine

the value of tan β. In this work we preform a detailed analysis of measuring top quark

polarization in the charged Higgs boson production channels gb → tH− and gb̄ → t̄H+. We

calculate the helicity amplitudes of the charged Higgs boson production and decay. Our

calculation shows that the top quark from the charged Higgs boson decay provides a good

19

QHC, Wan, Wang, Zhu, 1301.6608

Ddecay ⇠(mt cot�)2 � (mb tan�)2)(mt cot�)2 + (mb tan�)2)

Huitu, Rai, Rao, Rindani, Sharma, 1012.0527 Godbole, Hartgring, Niessen, White, 1111.0759 Gong, Si, Yang, Zheng,1210.7822

29

-

5) Top Quark Pair Plus JetsHeavy Quark Pair Production

Color Sextet/Triplet Scalar Pair Production

g

g

t

t̄

T/B

T̄ /B̄

Z/W

g

g

T

T̄

t

t̄

h

h

g

g

t

t̄

�6,3

�6,3

b

b̄

(Faked Top Quark Pair)

g

g

T

T̄

b

b̄

W

W

30

6) Top Quark Pair + Invisibles

Top-Quark Mediated Dark Matter Models

Dark Matter Effective Theory: Cheung, Mawatari, Senaha, Tseng, Yuan, 1009.0618 Gomez, Jackson, Shaughnessy, 1404.1918

g

g

t̃

˜̄t

t

t̄

χ̃0

χ̃0

g

g

T−

T−

t

t̄

AH

AH

SUSY LHT, UED

UV Completion Theory: Jackson, Servant, Shaughnessy, Tait, Taoso,1303.4717 31

t

Triple Top Quark Production


Others

t

tFCNC process

u,c g

Same-sign lepton pair32

Triple Top Quark Production

Topcolor-assisted technicolor model with large FCNC top-coupling to explain AFB(t)

Cui, Han, Schwartz (2011) Han, Liu, Wu, Yang (2012)

Chuan-Ren Chen (2014)

Barger, Keung, Yencho, 1001.0211

Leptophobic Z’ from U’(1) directly couples top-quark to u-quark to explain AFB(t)

g

u t

tt

Z 0

33

t

Four Top Quark!Production


Others

t

tt

34

Four Top Quark Productiont

t̄

t̄

tG0

t

t̄

t̄

t�8

t

t̄t̄

tt

t̄t̄

t

t

t̄

t̄

t�6

⇢⇡

Axigluon!KK Gluon

Color Octet!Scalar

Color Sextet!Scalar

TC2 Top Compositeness

Aguilar-Saavedra,!Santiago (2012)

Lillie, Shu, Tait (2007)

Chen, Klemm, Rentala, Wang!(2008)

SM QCD production @ NLO, ! Bevilacqua and Worek, 1206.3064 See Keaveney’s poster

Han, Liu, Wu, Yang (2012)Kumar, Tait, Veg-Morale (2009)

Plehn, Tait (2008)

35

t

Six or More Top Quark! Production


Others

t

tt

t36

Six or More Top Quark ProductionDeandrea, Deutschmann, 1405.6119

Color quantum #

37

Summary

38

Top quark as a probe of new physics

Gluino

Exotic Colored States

4th Gen

Vector Quark

FCNC

Charged  Higgs

AFB

Extra Gauge Bosons

New Heavy Quarks

CPHeavy Quark Production via pQCD

TopColor Sextet

It appears often in the decay of NP resonances

39

Top Quark Production: rich signatures

Top

Single Top Top Pair

Triple TopsFour Tops40Flavor changing+Flavor conserving


Top

Single Top

u

d t

bW’H+S6

u u

u/c tZ’ S0

b

g

t

W

b’

Top Pair

Triple TopsFour Tops40Flavor changing+Flavor conserving


Top

Single Top

u

d t

bW’H+S6

u u

u/c tZ’ S0

b

g

t

W

b’

Top Pair

Triple TopsFour Tops

�(3,1)6,3u

u

t

tg t

W 0t̄

bb

g

g

T

T̄

t

t̄

h

h

g

g

T−

T−

t

t̄

AH

AH

40Flavor changing+Flavor conserving


Top

Single Top

u

d t

bW’H+S6

u u

u/c tZ’ S0

b

g

t

W

b’

Top Pair


�(3,1)6,3u

u

t

tg t

W 0t̄

bb

g

g

T

T̄

t

t̄

h

h

g

g

T−

T−

t

t̄

AH

AH

gtt

Z 0tu



Top

Single Top

u

d t

bW’H+S6

u u

u/c tZ’ S0

b

g

t

W

b’

Top Pair


t

t̄t̄

t

t

t̄

t̄

tG0

�(3,1)6,3u

u

t

tg t

W 0t̄

bb

g

g

T

T̄

t

t̄

h

h

g

g

T−

T−

t

t̄

AH

AH

gtt

Z 0tu


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