Universal Extra-Dimension
at LHC
Swarup Kumar Majee
National Taiwan University
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.1
Plan
Hierarchy problem
Extra-dimensions
Flat extra-dimension (ADD and UED model)
Warped extra-dimension (RS-model)
Universal Extra Dimension (UED)
The Scalar, Fermion, and Gauge particles in the UED
model
Evolution of Gauge Couplings
Tree level and Radiative Corrected KK-Mass spectra
Decay modes and Branching ratios of KK-particle
Collider Signature of UED at LHC
Conclusion
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.2
Standard Model Higgs
SM: SU (3)C × SU (2)L × U (1)Y
| {z } |
{z
}
Strong(g)
UED@LHC
E−W (W ± ,Z and γ)
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.3
Standard Model Higgs
SM: SU (3)C × SU (2)L × U (1)Y
| {z } |
{z
}
Strong(g)
Higgs: Φ ≡ (1, 2, 1) ⇒
E−W (W ± ,Z and γ)
φ+
φ0
V = m2 Φ† Φ + λ(Φ† Φ)2
λ>0
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.3
Standard Model Higgs
SM: SU (3)C × SU (2)L × U (1)Y
| {z } |
{z
}
Strong(g)
Higgs: Φ ≡ (1, 2, 1) ⇒
E−W (W ± ,Z and γ)
φ+
φ0
V = m2 Φ† Φ + λ(Φ† Φ)2
λ>0
m2 > 0
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.3
Standard Model Higgs
SM: SU (3)C × SU (2)L × U (1)Y
| {z } |
{z
}
Strong(g)
Higgs: Φ ≡ (1, 2, 1) ⇒
E−W (W ± ,Z and γ)
φ+
φ0
V = m2 Φ† Φ + λ(Φ† Φ)2
λ>0
m2 > 0
m2 < 0 ⇒ h0|φ0 |0i = v
mH =
√
−2m2 , v =
UED@LHC
q
−m2
λ
= 246 GeV
S. K. Majee
Other components of Φ ⇒ Goldstone bosons
NCTS-NTHU, 17-May-2011 – p.3
Hierarchy problem
Due to femion loop n
o
R
4
Λ
−iλ
−iλ
f
f
i
d k
i
√
√
)
Πfhh = (−1) 0 (2π)
(
T
r
(
)
4
2 6k−mf
2 6p−6k−mf
=
λ2f 2
− 8π2 Λ
+ ...
m2H = m2H0 + δm2H
If ≃ 1016 GeV, required fine-tuning to 1 part in 1026 .
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.4
Hierarchy problem and SUSY
Due to femion loop n
o
R
4
Λ
−iλ
−iλ
f
f
i
d k
i
√
√
)
Πfhh = (−1) 0 (2π)
(
T
r
(
)
4
2 6k−mf
2 6p−6k−mf
=
λ2f 2
− 8π2 Λ
+ ...
m2H = m2H0 + δm2H
If ≃ 1016 GeV, required fine-tuning to 1 part in 1026 .
Due to scalar loop : δm2H =
λS
2
Λ
2
16π
− ...
λS = |λf |2 ⇒ Supersymmetry
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.4
Extra Dimensions
Consider, a massless particle in 5D Cartesian co-ordinate system, and assume that
the Lorentz invariance holds.
p2 = 0 = gAB pA pB = p0 2 − p
~2 ± p5 2 , with gAB = diag(1, −1 − 1 − 1, ±1)
So, p0 2 − p
~2 = pµ pµ = m2 = ∓p5 2 =⇒ time-like ED: m2 = −ve → tachyon
We consider only one space-type extra dimension (y)
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.5
Extra Dimensions
Consider, a massless particle in 5D Cartesian co-ordinate system, and assume that
the Lorentz invariance holds.
p2 = 0 = gAB pA pB = p0 2 − p
~2 ± p5 2 , with gAB = diag(1, −1 − 1 − 1, ±1)
So, p0 2 − p
~2 = pµ pµ = m2 = ∓p5 2 =⇒ time-like ED: m2 = −ve → tachyon
We consider only one space-type extra dimension (y)
free particle moving along x-direction =⇒ non-compact
ψ = Aeipx + Be−ipx , momentum p is not quantized
particle in a box =⇒ so V (x) = 0, 0 < x < L
= infinite elsewhere =⇒ compact
quantized momenta p =
UED@LHC
nπ
L
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.5
ADD-model
Consider a D-dimensional spacetime D = 4 + δ
Space is f actorised into R4 × Mδ , where Mδ is a
δ -dimensional space with volume Vδ ∼ Rδ .
This implies the four-dimensional effective MP l is
δ
R
MP2 l = MP2+δ
l(4+δ)
Assuming MP l(4+δ) ∼ mEW ,
δ
we get MP2 l = m2+δ
R
EW
implies, R ∼ 10
30
−17
δ
cm ×
2
1TeV 1+ δ
mEW
δ = 1 → R = 1013 cm is excluded due to the deviation
from Newtonian gravity. But, for δ = 2 it is in the mm
range.
( N. Arkani-Hamed, S. Dimopoulos and G. R. Dvali)
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.6
RS-model
(pic from José Santiago’s talk)
mIR = mU V exp(−πkR)
for kR ∼ 12, a mass mU V ∼ O(MP l ) on the UV-brane corresponds to a mass on the
IR brane with a value mIR ∼ O(MEW ).
UED@LHC
S. K. Majee
(Randall, Sundrum)
NCTS-NTHU, 17-May-2011 – p.7
UED at a glance
In UED model each particle can access all dimensions.
( Appelquist, Cheng, Deobrescu)
We consider only one space-type extra dimension (y)
So our co-ordinate system : {x(t, ~x), y}
Compactification : S 1 /Z2
Z2 symmetry : y ≡ −y necessary to get the chiral
fermions of the SM
Translational symmetry breaks
⇒ p5 , hence KK number (n)
is not conserved.
0
πR
y → y + πR symmetry preserve
⇒ KK parity ≡ (−1)n conserved.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.8
UED at a glance
n = 1 states must be produced in pairs
Lightest n = 1 state is stable ⇒ LKP
All heavier n = 1 states finally decay to LKP and
corresponding SM (n = 0) states
Collider signals are soft SM particles plus large 6 E
Limit on the R−1
250 - 300 GeV from gµ − 2, B0 − B̄0 mixing, Z → bb̄
(Agashe, Deshpande, Wu;
Weiler;
Chakraverty, Huitu, Kundu;
Buras, Spranger,
Oliver, Papavassiliou, Santamaria)
300 GeV from oblique parameters (Gogoladze, Macesanu)
600 GeV from b → sγ at NLO (Haisch, Weiler)
LKP dark matter ⇒ Upper bound ∼ 1 TeV from
overclosure of the universe (Servant, Tait)
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.9
Scalar, Fermion, and Gauge boson
Scalar :
φ(x, y)
UED@LHC
=
√
√
2
2πR
S. K. Majee
φ
(0)
(x) + √
2
2πR
∞
X
n=1
φ(n) (x) cos
ny
.
R
NCTS-NTHU, 17-May-2011 – p.10
Scalar, Fermion, and Gauge boson
Scalar :
φ(x, y)
Fermions :
Qi (x, y)
=
Ui (x, y)
=
Di (x, y)
=
UED@LHC
√
=
√
√
2
2πR
φ
(0)
(x) + √
2
2πR
∞
X
n=1
φ(n) (x) cos
ny
.
R
#
∞ X
√
ui
2
ny
ny
(n)
(n)
√
,
(x) + 2
QiL (x) cos
+ QiR (x) sin
di L
R
R
2πR
n=1
"
√
#
∞ X
√
ny
ny
2
(n)
(n)
√
+ UiL (x) sin
uiR (x) + 2
UiR (x) cos
,
R
R
2πR
n=1
"
√
#
∞
X
√
ny
ny
2
(n)
(n)
√
.
+ DiL (x) sin
diR (x) + 2
DiR (x) cos
R
R
2πR
n=1
"
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.10
Scalar, Fermion, and Gauge boson
Scalar :
φ(x, y)
Fermions :
Qi (x, y)
=
Ui (x, y)
=
Di (x, y)
=
√
=
√
2
2πR
φ
(0)
(x) + √
2
2πR
∞
X
φ(n) (x) cos
n=1
ny
.
R
#
∞ X
√
ui
2
ny
ny
(n)
(n)
√
,
(x) + 2
QiL (x) cos
+ QiR (x) sin
di L
R
R
2πR
n=1
"
√
#
∞ X
√
ny
ny
2
(n)
(n)
√
+ UiL (x) sin
uiR (x) + 2
UiR (x) cos
,
R
R
2πR
n=1
"
√
#
∞
X
√
ny
ny
2
(n)
(n)
√
.
+ DiL (x) sin
diR (x) + 2
DiR (x) cos
R
R
2πR
n=1
"
Gauge boson :
Aµ (x, y)
A5 (x, y)
UED@LHC
√
=
=
√
√
√
2
2πR
2
2πR
S. K. Majee
(0)
Aµ (x)
∞
X
n=1
+√
(n)
2
2πR
A5 (x) sin
∞
X
n=1
(n)
Aµ (x) cos
ny
,
R
ny
.
R
NCTS-NTHU, 17-May-2011 – p.10
Effects of KK-modes on RGE
RGE in SM :
3 =β
i
=
b
g
16π 2 E dg
i
SM (g)
dE
⇒
Solution :
bi
E
αi −1 (E) = αi −1 (MZ ) −
ln
with
2π MZ
UED@LHC
S. K. Majee
d
−1 (E)
α
i
dlnE


bi
= − 2π

41
10
− 19
6

bY
 


=
 b
.
 2L  

b3C
−7
NCTS-NTHU, 17-May-2011 – p.11
Effects of KK-modes on RGE
RGE in SM :
3 =β
i
=
b
g
16π 2 E dg
i
SM (g)
dE
⇒
Solution :
bi
E
αi −1 (E) = αi −1 (MZ ) −
ln
with
2π MZ
In UED,
d
−1 (E)
α
i
dlnE


bi
= − 2π

41
10
− 19
6

bY
 


=
 b
.
 2L  

b3C
−7
DDG-Nucl.Phys.B537:47-108,1999
i
= βSM (g) + (S − 1)βU ED (g)
16π 2 E dg
dE
where, S = ER
βU ED = b˜i gi 3 with



b̃Y

 
 b̃
 
 2L  = 
b̃3C
UED@LHC
S. K. Majee
81
10
7
6
−5
2


.

NCTS-NTHU, 17-May-2011 – p.11
Gauge Couplings
70
60
U(1)
40
α
−1
50
30
SU(2)
20
10
0
SU(3)
2
4
6
8
10
12
14
16
18
20
log 10(E/GeV)
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.12
Gauge Couplings
70
70
60
60
U(1)
50
40
40
α-1g
50
α
−1
U(1)
30
30
SU(2)
5 TeV
1 TeV
20
20
10
0
20 TeV
SU(2)
10
SU(3)
2
4
SU(3)
6
8
10
12
14
16
18
20
log 10(E/GeV)
0
2
2.5
3
3.5
4
4.5
log10(E/GeV)
5
5.5
6
6.5
(Bhattacharyya, Datta, Majee, Raychaudhuri)
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.12
Radiatvie Corrections
Cheng, Matchev, Schmaltz
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.13
Radiative corrections
Tree level n − th mode KK-mass mn =
p
m20 + n2 /R2
Consider the kinetic term of a scalar field as
Lkin = Z∂µ φ∂ µ φ − Z5 ∂5 φ∂ 5 φ,
Tree level KK masses originate from the kinetic term
in the y -direction.
If there is Lorentz invariance, then Z = Z5 , there is
no correction to those masses.
A direction is compactified ⇒ Lorentz invariance
breaks down.
Then, Z 6= Z5 , leading to ∆mn ∝ (Z − Z5 ).
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.14
Radiative: Bulk Corrections
These corrections are finite and nonzero only for
bosons.
These corrections, for a given field, are the same for
any KK mode.
For a KK boson mass mn (B), these corrections are
given by
δ m2n (B)
=
ζ(3)
κ 16π
4
1 2
R
κ = −39g12 /2, −5g22 /2 and −3g32 /2 for B n , W n and g n ,
respectively.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.15
Radiative: Orbifold Corrections
Orbifolding additionally breaks translational invariance in the y-direction.
The corrections to the KK masses arising from interactions localized at the fixed points
are logarithmically divergent.
δmn (f )
mn (f )
δm2n (B)
m2n (B)
g32
g22
g12
Λ2
ln 2 ,
= a
+b
+c
16π 2
16π 2
16π 2
µ
The mass squared matrix of the neutral KK gauge boson sector in the Bn , Wn3 basis is
given by


n2
R2
+
δ̂m2Bn + 41 g12 v 2
1
g g v2
4 1 2
n2
R2
+
1
g g v2
4 1 2
δ̂m2Wn + 14 g22 v 2


1 ∼ 0.01 (<< sin2 θ
For n = 1 and R−1 = 500 GeV, it turns out that sin2 θW
W ≃ 0.23),
i.e., γ 1 and Z 1 are primarily B 1 and W31 , respectively.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.16
Mass Spectra
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.17
Mass Spectra
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.17
Allowed transitions
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.18
Branching ratios
γ1 is the LKP. It is neutral and stable.
KK W - and Z -bosons
Hadronic decays closed.
Can not decay to their corresponding SM-mode and
LKP, as kinematically not allowed.
W1± and Z1 decay democratically to all lepton flavors:
±
±
1
ν
)
=
→
L
)
=
B(W
B(W1± → ν1 L±
1 0
1
0
6
∓
1
B(Z1 → ν1 ν̄0 ) = B(Z1 → L±
L
)
≃
1 0
6
for each generation.
∓
2
Z1 → ℓ ±
decays
are
suppressed
by
sin
θ1 .
ℓ
1 0
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.19
Branching ratios
γ1 is the LKP. It is neutral and stable.
KK W - and Z -bosons
Hadronic decays closed.
Can not decay to their corresponding SM-mode and
LKP, as kinematically not allowed.
W1± and Z1 decay democratically to all lepton flavors:
±
±
1
ν
)
=
→
L
)
=
B(W
B(W1± → ν1 L±
1 0
1
0
6
∓
1
B(Z1 → ν1 ν̄0 ) = B(Z1 → L±
L
)
≃
1 0
6
for each generation.
∓
2
Z1 → ℓ ±
decays
are
suppressed
by
sin
θ1 .
ℓ
1 0
KK leptons
The level 1 KK modes of the charged leptons and
neutrinos directly decay to γ1 and corresponding zero
mode states.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.19
Branching ratios
The heaviest KK particle at the 1st KK-level g1 .
B(g1 → Q1 Q0 ) ≃ B(g1 → q1 q0 ) ≃ 0.5.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.20
Branching ratios
The heaviest KK particle at the 1st KK-level g1 .
B(g1 → Q1 Q0 ) ≃ B(g1 → q1 q0 ) ≃ 0.5.
KK quarks
SU (2)-singlet quarks (q1 ):
B(q1 → Z1 q0 ) ≃ sin2 θ1 ∼ 10−2 − 10−3
B(q1 → γ1 q0 ) ≃ cos2 θ1 ∼ 1
SU (2)-doublet quarks (Q1 ):
SU (2)W -symmetry ⇒
B(Q1 → W1± Q′0 ) ≃ 2B(Q1 → Z1 Q0 )
and furthermore for massless Q0 we have
B(Q1 → W1± Q′0 ) ∼ 65%, B(Q1 → Z1 Q0 ) ∼ 33% and
B(Q1 → γ1 Q0 ) ∼ 2%.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.20
Collider Signature
Bhattacharyya, Datta, Majee, Raychaudhuri
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.21
Production
|M{qg → QV 1 }|2 =

2
{−2ŝt̂ − 4t̂m2 + 2ŝm2 + 4m2V 1 m2 }
παs (ŝ)(a2L + a2R ) {−2ŝt̂ + 2ŝmQ }
Q
Q
Q

+
6
ŝ2
(t̂ − m2 )2
Q

2
2
2
2
4
2{−2t̂m + 2(ŝ + t̂)mV 1 + 2mV 1 m − 2mV 1 }
Q
Q

+
2
ŝ(t̂ − m )
Q
Excited quark →
SU(2) Doublet(Q) (aR = 0)
Excited boson ↓
aL
γ1
UED@LHC
aR
g
√
2
W1
Z1
SU(2) Singlet (q) (aL = 0)
g
1
2 cos θW
T3 − e Q
eQ
cos θW
S. K. Majee
0
sin2
1
cos θW
1
θW
− 2 cosg θ1
W
eq
cos θW
eq
sin2
1
cos θW
1
θW
NCTS-NTHU, 17-May-2011 – p.22
Production Crosssection
10000
Production cross section (fb)
-
1
Q W
q γ
1
1 1
QZ
1 1
q γ
10
_
/s = 10 TeV
/
1
Q W
1 1
100
-
1
1000
_
// s = 14 TeV
1 1
QZ
1 1
Q γ
1
1
Q γ
1
1 1
q Z
1 1
q Z
0.1
300
UED@LHC
450
600
750
-1
R (GeV)
S. K. Majee
900 300
450
600
750
-1
R (GeV)
900 1000
NCTS-NTHU, 17-May-2011 – p.23
Basic cuts and nl crosssection
basic cuts
pjet
T > 20GeV
> 5GeV
plepton
T
> 25GeV
p6 miss
T
Mli lj > 5GeV
|η| < 2.5 for all leptons and jet
lepton isolation : ∆R > 0.7, (nl ≥ 2 cases)
crosssection (fb)
UED@LHC
Channel
0l
1l
2l
3l
4l
Signal (500 GeV)
106.4
17.92
29.58
9.39
1.01
Signal (1 TeV)
2.02
0.35
0.606
0.210
0.025
Background
4.7×105
1.3×106
8.6×104
1183.21
0.13
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.24
Two Leptons
Signal
Q1 W 1 production followed by Q1 → Q′ W 1
Q1 Z 1 production followed by Q1 → QZ 1
We separately consider ‘like-flavor’, i.e., e+ e− or µ+ µ− , as well as ‘unlike-flavor’,
i.e., µ+ e− + e+ µ− , in our discussion.
Background
dominanat: tt̄ and bb̄
severely cut down: pjet
T > 20GeV
W pair production in association with a jet.
Z pair (real or virtual)
Zγ ∗
Additional Cuts:
pT l1 < 25 GeV,
pT l2 < 25 GeV, and
|Ml1 l2 − MZ | > 10 GeV
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.25
1l2
dσ/dMl
0.9
0.8
0.4
0.6
0.3
0
1.2
0.9
0.9
0.6
0.3
0
0.6
0.3
0
0
5 10 15 20 25 30
l
pT 1
S. K. Majee
0
0
5 10 15 20 25 30
l
pT 2
20 40 60 80 100
Ml l
12
dσ/dMl
1.2
0.5
0.4
0.3
0.2
0.1
0
5 10 15 20 25 30
l
pT 2
1l 2
0
30 60 90 120 150
Ml l
12
0
5 10 15 20 25 30
l
pT 1
0.3
0
1l 2
0.9
0.6
20 40 60 80 100
l
pT 2
dσ/dMl
0.9
dσ/dpTl2
1.2
40 80 120 160 200
Ml l
12
1.2
0
dσ/dpTl2
dσ/dpTl1
0
1.2
1.2
0
0.4
30 60 90 120 150
l
pT 2
0
0.3
0.8
1.6
5 10 15 20 25 30
l
pT 1
0.6
1.2
0
0
0
UED@LHC
1.6
1l2
5.5
4.4
3.3
2.2
1.1
0
0
dσ/dpTl1
30 60 90 120 150
l
pT 1
dσ/dpTl2
dσ/dpTl1
0
3
2.4
1.8
1.2
0.6
0
dσ/dMl
5.5
4.4
3.3
2.2
1.1
0
dσ/dpTl2
dσ/dpTl1
Two Leptons
0.5
0.4
0.3
0.2
0.1
0
0
20 40 60 80 100
Ml l
12
NCTS-NTHU, 17-May-2011 – p.26
Two Leptons
√
s
→
14 TeV
10 TeV
Cut used ↓
Signal
Background
Signal
Background
Basic cuts
29.58 (43.10)
8.6×104 (17×104 )
10.0 (14.6)
5×104 (9.6×104 )
Lepton isolation
24.24 (35.24)
218.38 (429.64)
8.28 (12.06)
108.54 (212.78)
pT l1 < 25 GeV
21.66 (30.88)
78.67 (154.90)
7.52 (10.74)
41.10 (80.70)
pT l2 < 25 GeV
12.58 (18.00)
9.44 (18.40)
4.53 (6.52)
5.27 (10.22)
|Ml1 l2 − MZ | > 10
12.52 (17.88)
9.18 (17.98)
4.51 (6.48)
5.17 (10.08)
Cross section (in fb) at the LHC signal and background for the like-flavour(unlike-flavour)
dilepton plus missing pT plus single jet for R−1 = 500GeV.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.27
Three Leptons
Signal
Q1 W 1 production followed by Q1 → Q0 Z 1
Q1 Z 1 production followed by Q1 → Q′0 W 1
Background tt̄ production, W Z or W γ ∗ production in
association with a jet.
Additional Cuts
pT l1 < 25 GeV,
pT l2 < 25 GeV, and
|Ml1 l2 − MZ | > 10 GeV.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.28
Three Leptons
√
s
→
14 TeV
10 TeV
Cut used ↓
Signal
Background
Signal
Background
Basic cuts
9.39
1183.21
3.21
555.85
Lepton isolation
6.96
21.69
2.41
10.53
pT l2 < 25 GeV
5.63
4.09
2.01
1.75
pT l3 < 40 GeV
5.12
1.31
1.86
0.64
|Mli lj − MZ | > 10 GeV
5.03
1.16
1.82
0.57
Cross section (in f b) at the LHC of signal and background for the trilepton plus one jet and
missing pT channel for R−1 = 500 GeV.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.29
Four Leptons
Signal Q1 Z 1 production followed by Q1 → Q0 Z 1
|Mli lj − MZ | > 10 GeV for i, j = 1,2,3,4, i 6= j .
√
s
→
14 TeV
10 TeV
Cut used ↓
Signal
Background
Signal
Background
Basic cuts
1.01
0.130
0.350
0.068
Lepton isolation
0.665
0.029
0.233
0.015
|Mli lj − MZ | > 10 GeV
0.573
0.004
0.206
0.002
Cross section (in f b) at the LHC of signal and background for the tetralepton plus one jet and
missing pT channel for R−1 = 500 GeV.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.30
Luminosity plot for a 5σ signal
-1
Integrated Luminosity (fb )
1000
100
p
4-Le
)
Le
U
ep
Le
p(
2-
2-
4-L
)
U
p(
10
ep
3-L
L)
(
p
e
2-L
0.1
300
UED@LHC
400
-
1
L)
p(
-Le
_
// s = 14 TeV
500
600
-1
R (GeV)
S. K. Majee
700
2
300
800
400
-
ep
3-L
_
/s = 10 TeV
/
500
R (GeV)
600
700
-1
NCTS-NTHU, 17-May-2011 – p.31
Conclusions
we have focussed on the production of the n = 1 excitation of a EW gauge boson along
with an n = 1 excited quark.
First, we imposed some basic cuts to suit LHC observability:
the leptons are required to satisfy pT > 5 GeV,
the jet must have a pT not less than 20 GeV,
the missing transverse momentum must be more than 25 GeV.
∆R > 0.7
Single jet + p/T + two leptons: Signal: 12.52 f b,
Background: 9.18 f b,
Single jet + p/T + three leptons: Signal: 5.00 f b,
Background: 1.02 f b,
Single jet + p/T + four leptons: Signal: 0.573 f b,
Background: 0.004 f b.
The analysis performed here is based on a parton-level simulation and is of an
exploratory nature.
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.32
UED@LHC
S. K. Majee
NCTS-NTHU, 17-May-2011 – p.33