Physics & Perspectives of the ILC
Shigeki Matsumoto (Kavli IPMU)
1. An update report on the current status
of ILC project, for an ‘academic expert
committee’ was established under MEXT.
2. Physics perspectives at ILC experiment
Current status of ILC in Japan
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JP Government (MEXT) activities
May 27, 2013
Asking Science Council of Japan (SCJ)
to deliberate the ILC project from an
academic point of view.
LCC (LC collaboration) activities
including ILC TDR completion, etc.
Sep 30, 2013 (SCI)
A report was submitted to MEXT.
Dec 24, 2013The conclusion of the report included (translation is official)
$0.5M
for investigatory study was
The Committee suggests that the government of Japan should (1) secure the budget
approved.
same amount
required forThe
the investigation
of was
various issues to determine the possibility of hosting the
approved
the following
ILC, and (2)for
conduct
intensive year.
studies and discussions among stakeholders, including
authorities from outside high-energy physics as well as the government bodies involved
May
08, 2014:
1st Meeting
ACE
May
01,
2014
for the
next
two to three years. Before making the final
decision
of whether
the ILCofshould
be hosted
in Japan,
thecommittee
issues and concerns described
in this
be fully
An
academic
expert
Nov
05,document
2014: 2ndshould
Meeting
of ACE
investigated
and a clear vision
solutions needs to be provided. Theyrdinclude the whole
(ACE)
was established
underfor
MEXT.
Apr 10, 2015: 3 Meeting of ACE
profile of project cost for the construction, operation, upgrades and decommissioning, as
[Interim
reportare
came
well as prospect for cost-sharing among the countries involved.
Also included
the out]
Jun XX, 2015:
4th Meeting of ACE
issues
related
to human
resources and management/operation
organization.
By
Mar
31, 2016
(Extendable)
…
MEXT will receive a report from ACE.
[http://www.scj.go.jp/en/report/index.html]
Current status of ILC in Japan
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Academic Expert Committee (有識者会議)
[http://www.mext.go.jp/b_menu/shingi/chousa/shinkou/038/index.htm]
Physics Working Group
TDR Working group
Physics significance.
Validation of TDR
Nomura Research Institute
Economical ripple effect, etc.
Entrustment of Investigation Services
Interim report of AEC is composed of reports from these groups.
Physics Working Group involves 15 members from
particle physics, nuclear physics, astrophysics, etc.
From the report of the Physics Working Group (Translation is “not” official):
Conclusion: The ILC physics case outlines the possible issues concerning particle physics,
and therefore emphasizes its important scientific significance!
Important factors to consider:
In regards to activity plans of the ILC, it is important to establish a proper
managing system in order to avoid any further delays. Failure to make timely
decisions could potentially damage the international collaboration, etc.
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Physics perspectives at the ILC
Why the electroweak symmetry is broken at O(100)GeV?
Theory
New physics at the TeV scale
Precise Higgs measurements
(e.g. Yukawa & self couplings)
• Supersymmetry scenario?
• Composite Higgs scenario?
•
…
Precise top measurements
(e.g. mt, ttZ & tbW couplings)
Different mechanism of EWSB
Search for new particles
(e.g. non-colored particles)
• Boundary condition @ Mpl?
• Multiverse scenario?
•
…
Precise measurements of SM
processes (e.g. Z’, ee  ff)
…
What is dark matter?
We are now at a big branching point!
Precise Higgs measurements
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Please refer also to K. Fujii’s talk slides in PHENO 2014
I = 1.15ab–1 @ 250GeV ⊕ 1.6ab–1 @ 500(550)GeV & II = ⊕ 2.5ab–1 @
1TeV
Dmh Gh
kt
kb
kt
kc
kZ
kW
kg
kg
l
I. 30MeV 2.5% 7.8(2.3)% 0.8% 1.2% 1.5% 0.5% 0.6% 1.2% 4.5(1.7)% 46%
II.
---
2.3% 1.9(1.7)% 0.7% 0.9% 1.0% 0.5% 0.6% 0.9% 2.4(0.8)% 13%
↳ [s½ = 550GeV I/O 500GeV]
・ s×BR measured in each mode
・ s measured from recoil mass,
namely, e–e+  H Z X m–m+.
・ Total width of H obtained by
e–e+  nn H  nn W–W+.
(s½ > 350GeV is crucial.)
Coupling determinations!
An implication to SUSY scenario
Fraction excluded by ILC
ILC can determine couplings
in a model independent way
[LHC-ILC synergy] ↲
[Endo et al. 1502.03959]
mgluino = mstop = 3—5TeV
tanb = 5—50 , etc.
2SD
mh = 126GeV &several constraints
are already included in the analysis.
mA = a few TeV can be covered.
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Precise top measurements
Please refer also to K. Fujii’s talk slides in PHENO 2014
10fb–1 each (11bins) @ 340-350GeV ⊕ 500fb–1 @ 500GeV
Dmt
100MeV
DGt
32MeV
~
Fg1V
±0.002
Stability of the Higgs potential
~
FZ1V
±0.002
~
FZ1A
~
Fg2V
~
FZ2V
±0.006
±0.001
±0.002
An implication to CHMs, etc.
300fb–1
@13TeV
NP scale ~ 1TeV
500fb–1
@500GeV
[Degrassi et al. 1205.6497]
[Barducci et al. 1504.05407]
Boundary condition l(mpl) = 0?
Precise measurements of mt!
Precise top measurements can
be used to discriminate NPMs!
Search for WIMP dark matter
It is convenient to categorize WIMP DM candidates according to their
quantum numbers: Spin and Weak isospin. (EM and color charges = 0)
Weak isospin of the WIMP DM
1. Singlet-like case:
WIMP DM is an (almost) singlet under SM gauge interactions SU(3)c
× SU(2)L × U(1)Y. Typical examples are the bino, the singlino, etc.
2. Multiplet-like case:
WIMP DM is an (almost) neutral component of SU(2)L multiplet. It is
usually degenerate with charged SU(2)L components. Typical
examples are the Higgsino, the wino, the minimal DM, etc.
3. Mixed case:
WIIMP DM is a mixture of different SU(2)L representations due to
the electroweak symmetry breaking. The DM has a sizable coupling
to the Higgs boson in this case, and direct detection experiments
of DM play the most important role.
We consider two cases （1 and 2） with the WIMP DM being a fermion.
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Search for WIMP DM (Multiplet-like case)
Production of SU(2)L partners
500fb–1@500GeV
g*, Z*
g
95%C.L.
[Choi et al. 1503.08538]
Signal: g + E/+ soft tracks, etc.
(m(c±), Dm(c±, c0), s×BR obtained.)
mDM < s½/2 – 20GeV explored!
[Berggren et al. 1307.3566]
Indirect probe of the DM multiplet
DM multiplet
Wino @ 95%C.L. & 2ab–1
f
–
f
Signal: Interference with SM one
(mass reach ∝ s¼ × L¼, L: luminosity)
[Harigaya, S.M., Shirai, et al, 1504.03402]
Sys1. e:0.2%, m:0.15%, b:0.5%, c:1.0%
Sys2. e:0.4%, m:0.30%, b:1.0%, c:2.0%
mDM < s½/2 + 200GeV explored!
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Search for WIMP DM (Singlet-like case)
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No renormalizable interactions between the WIMP DM and SM particles.
 Considering higher dimensional interactions up to dimension six.
– g c)(e– gme )]
[7 SM gauge invariant Ops with CP/Flavor inv. e.g. (c/L2)(cg
m 5
R
R
This EFT may not work for physics of energetic colliders such as ILC.
 Considering two different UV theories reproducing the EFT.
UV+ ⊃ Heavy Z2-even particles
e
New vector boson
with a mass of L
e
c
c
e
e
Dim6 Operator
Very preliminary
WDMh2 by cc  l+l–
L∞
EFT ⊃ Higher dimensional Ops.
[S.M., Mukhopadhyay, Tsai, 1047.1859, etc.]
c
c
L∞
UV– ⊃ Heavy Z2-odd particles
e
New scalar or vector
boson with a mass of L
e
c
c
EFT, UV+, UV– are used for collider signals
and we accept the most conservative one.
Summary
• About the current status of the ILC project in Japan, MEXT
established the academic expert committee and it continues the
discussion. MEXT will receive an official report by March 31, 2016. It
has been reported by the physics working group that the ILC has
important scientific significance!
• About physics perspectives (precise measurements), the ILC will
determine the Higgs and the top properties at about 1% level, which
are very useful to search for physics behind the electroweak
symmetry breaking. These were well studies, but still being developed.
E.g. Tao Han, et al. 1504.01399.
• About physics perspectives (new particle searches), the ILC will offer
another way to search for WIMIP dark matters.
New particle searches are also very important to search for new
physics at the TeV scale. There are some comprehensive studies for
the SUSY scenario. E.g. Arbey et al. 1504.05091 and Vries et al.
1504.03260 (pMSSM study).
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