Unusual signatures of spin-1 resonances

keywords: Z-prime, Z-star W-prime,W-star

based on0807.50870801.4235

Mihail V. Chizhov Sofia University, Bulgaria

andJINR, Russia

03/08/2009 2

g, W±, Z …

… till now:

abelian U(1)’ extension → Z’

5VZ Ag g Z

g g L

or adjoint representation of SU(2)’ extension → Z’, W’

5V AW Wg g

g g L

Canonical signature of spin-1 resonance

03/08/2009

is not complete !3

03/08/2009 4

What about bosons in fundamental reps. of SU(2)L

i.e. with the internal quantum numbers identical to the SMHiggs doublet. Due to their quantum numbers, to the leading order such bosons can only have anomalous chiral interactions with the SM fermions,

**

* * **

**

** h.c.

uL L R

dL L R

Z Wg u d u

g

ZZWW

WWu

ZZd d

L

SU(3) extensions, extra spatial dimentions… MC and G. Dvali, in

preparation

Technicolor

03/08/2009 5

techni-pions, techni-rhos, techni-omegas … What else?

5q q Ag g q Vq

g

* *5q A Aq

g

? ? ?

03/08/2009

Invariant dilepton mass distributions

Z’

Z

Z*

MZ

Several models predict high mass resonances that could decay into dileptons (Z’, G, TC, KK, …)

6

03/08/2009

Angular distribution of Z*

22100 cosd

Lqp pLqL

L

Z*

7

Spin-1 and graviton angular distributions

* 21

3 cos *2

P

* *1 1P

03/08/2009 8

Comparison between Z’ and Z*for

03/08/2009 9

*-1

Z 1 TeV, 100 pb @ 10 TeV ZM M L

800 900 1000 1100 12000

10

20

30

40

E

vent

s/40

GeV

/100

pb-1

Mee

[GeV]420 460 500 540 580

0

5

10

15

Eve

nts/

40 G

eV/1

00 p

b-1

pT [GeV]

-4 -2 0 2 40

5

10

15

20

Eve

nts/

2.0/

100

pb-1

(lepton)-(antilepton)-0,8 -0,4 0,0 0,4 0,8

5

10

15

20

Eve

nts/

0.4/

100

pb-1

cos *

Conclusions

There are intense searches for excited fermions, but not for excited bosons at electroweak scale.

In contrast to the gauge bosons the excited bosons have anomalous chiral couplings to matter. This leads to a distinctive signature of their production at the hadron colliders.

The clearest channel for their discovery by the early LHC data should be the dilepton one.

03/08/2009 10

03/08/2009 11

*Z

03/08/2009

*Z

12

Excited particles (compositeness)

* why not Z* ?

* *g Z Z

L

* **Z Zg Z

L

03/08/2009

5VZ Ag g Z

g g LZ* has different interactions than Z’ !

Searches for excited fermions * have been fulfilled at all powerful colliders, such as LEP, HERA and Tevatron. They are also included in experimental program at the LHC.

13

Dilepton resonances

29/04/2009 14

M=1 TeVZ’

Z*

22 2

d d dd dcos dc

dcos 2d c s oo sT T Mp p

2

2

2 2

4cos 1 ;

d cos 2 :d cos

T

T

pM

p M

03/08/2009

cos2LMp

Tp2M

Jacobian factor for cos Tp

w r o n g !

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

V. Barger “Collider physics” 15