Search for new type resonancesin dilepton LHC data

M.V. ChizhovSofia University and JINR

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Di-electron:• Data with 5 GeV ET di-

electron trigger (prescaled in later data)

• Trigger selection produces shoulder around 15 GeV

Di-Muon: Leading muon, pT>15

GeV, second muon, pT>2.5 GeV

1980s1970s1960s

Ep =3.5 TeV is fixed!

Di-Muon and Di-Electron Spectra

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x is the fraction of the proton’s momentumcarried by the selected quark.

Parton Distribution Functions (PDFs)

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Resonance production

beam beam

1 1

2 2

21 1

2 21 2 1 2 1

*

2

collision energy: 1,0,0,1

patron momenta: 1,0,0, 1

ˆMandelstam invariants: ,

ˆ ˆ ,

q q

s E Ep x Ep x E

t p

u p s p p x s

Z

x

1 1 2 21 2 1

**

**

*

2,

2

0

2

0

2 2

2

, ,

ˆˆ ˆ ˆ , , , ,

ˆˆ ˆ, ,

ˆ

q qq q

qq

Z

Z

B dx dx f x f x

s t u B

A s t

Z

M Z

Z

M

u B

s M

*

ˆ

B

s

Z

M

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Cross section

.

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S=1/2

S=1

R LL L RR

Parity transformation Charge conjugation

L LR RLR RL

T T

T T

AV

AV

Spin-1 states

,Z , Z Z*Z*7

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← ← LL

LL V A

→ → RR

RR V A

← →

*

R L

*

T T

V V

L R

→ ←

L R

* *5 A A

T T

i

R L

Minimal and anomalous couplings

Antisymmetric Tensor Fields(the massive case)

****

211

AAM

VVM

T

02

;01 ****

AT

MAVT

MV

5* * * *

=

Vg giM M

V A A

( ) ( )2 2 L RR L T Tg gT T

CP even CP odd

6 = 3 + 3

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5VZ Ag g Z

L

Difference b/w Z’ and Z* couplings

* **Z Zg Z

L

and

Z*R

L L

R

2

22 2 2ˆ

ˆˆ

s M M

u t

22 2

2

2

2

ˆ

ˆ

ˆ

u

t

s M M

LL LLRR RRLL RRRR LL

kj kj kjZ’

LR

LR

LR

LR

Z’

Z

Z*

MZ

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Invariant dilepton mass distributions

Several models predict new high mass neutral resonances that could decay into dilepton pairs(Z’, G*, TC, KK, …)

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22 2 2 2res res

1

M M M

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Angular distributions

=|12 |

Spin 2

Spin 0

Spin 1

QCD

Z* (excited spin 1)

ln 3 8 1.76

2η ln tg2

=/2

q q

h , Z’ , G* , …

=/4

q q

Z*

incomplete!14/06/2012 13

Z’ and graviton angular distributions

* *1 1P

21 * 20,0 1

3* cos *2

d d Z f f d P

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arXiv:1109.6876v1 [hep-ph] 30 Sep 2011

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CMS: arXiv:1206.1849

It is interesting to know:What is angular distributionsfor on-peak events?

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SM slave

Dark matter

Inflation Gravitation Baryon asymmetry

Hierarchy problem

16

Can we escape from SM prison?

17

The main theoretical motivation for beyond the Standard Model physics around TeV energies (LHC) is provided by the Hierarchy Problem, an inexplicable the UltraViolet stability of the weak interaction scale (MW,Z = 102 GeV) versus the Planck mass (MP = 1019 GeV),

WHY IS M2W,Z/M2

P = 10-34 ?

Introduction of new spin-1 bosons with the internal quantum numbers identical to the Standard Model Higgs doublet can help to solve by the Hierarchy Problem.

MP

1019 GeV102 GeV

MW,Z

103 GeV

MW*,Z*

Motivation for SM extension

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*

0 *

H WZH

M. Chizhov and G. Dvali “Origin and Phenomenology of Weak-Doublet Spin-1 Bosons”, Phys.Lett. B703 (2011) 593-598; arXiv:0908.0924

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*

*

3 1

*

2

*

2

1 3

ZW

W W iWW iW W

BZ W

They belong to fragments 2 (2) and become massive during the spontaneous symmetry breaking SU(3) →SU(2)U(1) by the two independent Higgs triplets 3H=1

H +2 H и 3’H=1’ H +2’ H.The lightness of the Higgs doublets is guaranteed, because they are related to the vectors by symmetry.

1. SU(3) extension of SM

New vector bosons aretransformed under fundamental representation of SU(2)L

(coset gauge bosons)

Z.G. Berezhiani & G.Dvali, Bull. Lebedev Phys. Inst. 5(1989)55; Kratk. Soobshch. Fiz. 5(1989)42;G. Dvali, G.F. Giudice and A. Pomarol, Nucl. Phys. B478 (1996) 31;G.R. Dvali, Phys. Lett. B 324 (1994) 59.

SU(3) SU(2)U(1) 8=3+2+2+1

18

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Standard Model symmetry SU(2)LU(1) Y

L L Rg u d d

**

**

WWZZ

q

* W *

UD

D p

p'

Rk

uL

dL

dR

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2. Extra dimensions

* 0

**

*

, ..., ...

,,

M

M

WWZ

HHZ

Let us consider a doublet of the gauge fields in N-dimension Minkowski space. Then its the fifth and the subsequent components can play a role of the Higgs fields(so-called Gauge-Higgs unification)

The lightness of the Higgs doublets is guaranteed by the gauge symmetry. This symmetry is spontaneously broken by compactification. In this way the mass of the Higgs doublet is controlled by the compactification scale, as opposed tothe high-dimensional cutoff of the theory.

N.S. Manton, Nucl. Phys. B 158 (1979) 141; D.B. Fairlie, J. Phys. G 5 (1979) L55; Phys. Lett. B 82 (1979) 97.

* *

**

**

**

** h.c.

dL L R

uL L R

Z W

g u d d

g

WWZZ

ZZu

WWd u

L

3. Technicolor

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q Vq

techni-, techni-r, techni-w … What else?

10

s

5q q A

techni-a, techni-f11

s

* *5q A Aq

techni-b, techni-h01

s

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Low energy searches

Muon decay → е е Radiative pion decay → е е Neutron decay n → p е е

Kaon decay K → е е Lepton anomalous magnetic moment …

2 2

2

*

2

2suppressed by ZM

g qq

Large Hadron Collider

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We predict an existence of new excitedchiral particles W* and Z* with new

unique properties.

ATLAS is already looking for them!

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Theoretical comparision between Z’ and Z*

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800 900 1000 1100 12000

5

10

15

20

25

30

35

E

vent

s/40

GeV

/100

pb-1

Mee [GeV]800 900 1000 1100 1200

0

5

10

15

20

25

30

35

Eve

nts/

40 G

eV/1

00 p

b-1

Mee [GeV]

invariant mass

420 460 500 540 5800

5

10

15

Eve

nts/

40 G

eV/1

00 p

b-1

pT [GeV]

420 460 500 540 5800

5

10

15

Eve

nts/

40 G

eV/1

00 p

b-1

pT [GeV]

transverse momentum

-4 -2 0 2 40

5

10

15

20

Eve

nts/

2.0/

100

pb-1

(lepton)-(antilepton)-4 -2 0 2 4

0

5

10

15

20

Eve

nts/

2.0/

100

pb-1

(lepton)-(antilepton)

pseudorapidity difference

-0,8 -0,4 0,0 0,4 0,80

5

10

15

20

Eve

nts/

0.4/

100

pb-1

cos*CS

-0,8 -0,4 0,0 0,4 0,80

5

10

15

20

E

vent

s/0.

4/10

0 pb

-1

cos*CS

angular distribution

M. Chizhov, Disentangling between Z’ and Z* with first LHC data, arXiv:0807.5087

“The divergence at /2 which is the upper endpoint pT M/2 of the pT distribution stems from the Jacobian factor and is known as a Jacobian peak; it is characteristic of all two-body decays …”

Vernon D. Barger, Roger J.N. Phillips “Collider Physics”

M=1 TeVZ’

Z*

T T

d d dd d cos

dcos 2sind cos d cosp p M

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T

T

sin2

d cos 2sind cos

Mp

p M

2M

Jacobian factor for cos pT

w r o n g !31

Hadron collidersor search for heavy bosons beyond W± and Z

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p p colliders (Tevatron: 6.3 km)

CM980 GeV, 980 GeV; =1960 GeV

1960 GeV 6 330 GeVp pE E E

(LHC: 27 km)CM7000 GeV, 7000 GeV; =14000 GeV

1400

(3500) (3500) (7000)

(70 GeV 6 2330 GeV000) (1165) p pE E E

A hadron collider is the discovery machine. The production mechanism for new bosons at a hadron collider is qq annihilation. A presence of partons with a broad range of different momenta allows to flush the whole energetically accessible region, roughly, up to

(rule of thumb)CM1 2 CM CM

1

2

1

3

6EM x x E x E x

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The ATLAS Collaboration “Search for high-mass states with one lepton plus missing transverse momentum in proton-proton collisions at √s = 7 TeV with the ATLAS detector”, Phys. Lett. B701 (2011) 50; arXiv:1103.1391

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Z*

The ATLAS Collaboration “Search for high mass dilepton resonances in pp collisions at √s=7 TeV with the ATLAS experiment”, Phys. Lett. B700 (2011) 163; arXiv:1103.6218

Z*

Z*

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CMS: arXiv:1206.1849

I am very interested to know:What is angular distributionsfor the on-peak CMS events?

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Thank you for your attention!