talk @ beyond the standard model in okinawa 2016 2016.03.02
TRANSCRIPT
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The 750 GeV di-photon excess at Future colliders
Yoshitaro Takaesu U of Tokyo
In collaboration with H.Ito and T.Moroi: 1601.01144
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ATLAS and CMS observed an excess @ m�� � 750 GeV
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Properties of the 750 GeV resonance
p
p
�
��
m� � 750 GeV
arXiv:1601.03696
� O(1) fb
�� � 50 GeV?
spin 0 or 2
We consider spin 0 Narrow width resonance in this talk.
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Effective theory for the 750 GeV resonance
* We consider a 750 GeV pseudo-‐‑‒scalar in this talk. (Partial decay widths are almost the same for scalar case.) * We do not discuss the origin of this effective interactions.
1���
1��Z
1�ZZ�
� �
Z
Z
Z
1�2
W+
W�1�3 g
g
1���
=cos2 �W
�1+
sin2 �W
�2
1��Z
= 2 sin �W cos �W
�� 1
�1+
1�2
�
Check the decay modes as much as possible! (Only mode is observed so far.)��
Le� =��1
Bµ�B̃µ� +��2
W iµ�W̃ iµ� +
��3
Gaµ�G̃aµ�
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Partial decay width of the 750 GeV scalar
(m� � mZ ,mW )
1���
=cos2 �W
�1+
sin2 �W
�2
1��Z
= 2 sin �W cos �W
�� 1
�1+
1�2
�
1�ZZ
=sin2 �W
�1+
cos2 �W
�2
�
�
�
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Parameterization
Λ1: output (irrelevant to this Talk)
: free parameters ( ) �� � m�
�1, �2, �3, �� : model parameters (allowing invisible decay)
�(pp� �� ��) � �gg���
��
C13TeVgg
m�spp(NWA, gluon fusion)C13 TeV
gg : PDF factor
�1
�2,
�3
�1, ��
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Total width and Λ1
�� = ��� + ��Z + �ZZ + �WW + �gg =�gg���
�(pp� �� ��)C13TeV
gg
m�spp
to explain the excess
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LHC cross sections (EW)
�Z
��
= 6 fb�(pp� �� AB) � �(pp� �� ��)� Br(�� AB)
Br(�� ��)
ZZ
WW
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LHC Run-‐‑‒I constraint
�Z
��
Run-‐‑‒I�Z
95% C.L. exclusion
ZZ
WW
Λ1/Λ2 < -‐‑‒0.5 and Λ1/Λ2 > 6 were excluded (γZ).
ATLAS: 1407.81501512.04933
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EW Sensitivity at the HL-‐‑‒LHC 3 ab�1
EW decay modes may not be detected at the LHC if 0 < Λ1/Λ2 < 1.5.
95% C.L. exclusion
�Z
��
ZZ
WW
Run-‐‑‒I�Z
HL-‐‑‒LHC 3 ab�1
�Z andZZZZ
ATL-‐‑‒PHYS-‐‑‒PUB-‐‑‒2013-‐‑‒016 (ZZ)1512.05542 (γZ)
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LHC cross sections (gg)
Run-‐‑‒I�Z
gg decay mode depends on Λ3/Λ1.
Λ3/Λ1 = 0.1
Λ3/Λ1 = 1
Λ3/Λ1 = 10gg
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gg Sensitivity at the HL-‐‑‒LHC
Run-‐‑‒I�Z
gg decay mode may not be detected if Λ3/Λ1 > 1.
HL-‐‑‒LHC 3/ab 95% exclusion (rough estimate)
3 ab�1
ATL-‐‑‒PHYS-‐‑‒PUB-‐‑‒2015-‐‑‒004: di-‐‑‒jet limit QBH (750 GeV) with 50% acceptance
Λ3/Λ1 = 0.1
Λ3/Λ1 = 1
Λ3/Λ1 = 10gg
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How to search the unexplored region ?
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1TeV ILC ?Cross sections
(1TeV)・ILC�(ee� �X � AAX) � 1
�21
�̃(ee� �X)[�1/�2]1
���
����AA
��
� �̃(ee� �X)[�1/�2]1
�̃�� [�1/�2]�(pp� �� ��)
kA
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1TeV ILC ?
How about 1TeV Photon LC ?
gg or di-‐‑‒boson modes are detectable at ? (under investigation)
if we can have a 1TeV ILC ..
�gg < 0.012 fb
1 ab�1
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Photon-‐‑‒Photon collider option
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Cross section at Photon collider
(NWA)
gluon fusion:
photon fusion: k� � 240 [fb/GeV]
� 8000 [fb/GeV]
(A = g, �)
(13TeV)
A
A�AA
kg =�2C13 TeV
gg
8m�spp
C13 TeVgg : PDF factor
(1601.00638)
(1TeV)
�(pp� �� ��) � kA�AA���
��
�(�� � �� AA) �C1TeV
��
m�see
����AA
��
�C1TeV
��
m�see
1kA
�(pp� �� AA)
C1TeV�� : photon luminosity factor
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Background estimation
Sensitivity to detect the VVʼ’ decay mode
= 0.9
for γγ final statefor other final states
(well covering detector resolusion, for narrow width signal)
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Detectability at collider � �
1. Λ3/Λ1 = 1 (gluon fusion Φ production @ LHC)gg mode is easily detected. Three EW di-‐‑‒boson modes are detected at .
Lee = 1ab�1
1 ab�1
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Detectability at collider � �
2. Λ3/Λ1 = 50 (photon fusion Φ production @ LHC)EW di-‐‑‒boson modes are easily detected. Even gg mode would be detected at . (BG ~∼ 24 fb)1 ab�1
For 5σ detectionWW: > 10 fb ZZ: > 1 fb γZ: > 0.8 fb gg: > 1 fb
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Summary
We discussed the detectability of decay modes of 750 GeV scalar/pseudo-‐‑‒scalar at future colliders, assuming a simple effective Lagrangian.
1TeV photon collider (ILC?) would be useful to explore beyond the reach of the LHC.
Width? Invisible decay? CP property?