unusual signatures of spin-1 resonances
DESCRIPTION
based on 0807.5087 0801.4235. Unusual signatures of spin-1 resonances. keywords: Z-prime , Z-star W-prime , W-star. Mihail V. Chizhov Sofia University, Bulgaria a nd JINR, Russia. g , W ± , Z …. … till now:. a belian U(1)’ extension → Z’. - PowerPoint PPT PresentationTRANSCRIPT
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