rey.hori / KEK

International Linear Collider

Daniel Jeans

IPNS / KEK

2023/MarchCosmic Microwave
Background:imprint of inflation,
dark energy, dark matter, ...

Electro-weaktransition
Electro-weak physics
should contain imprint ofphysics at much higher energy

3
kek50th anniversaryElectro-weak transition
Higgs potential changes shapeV(φ)φ

Higgs particle: excitation of Higgs field
different to all otherfundamental particles
not “matter”, not “force”, no spin4
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why did the transition happen ?
Is the Higgs potential as we expect
how fast did it happen ?
did it cause the universe’santi-matter to disappear ?

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is our current vacuum
really stable ?
might our vacuum
spontaneously decay ?

5

we’ve observed allparticles of theStandard Model...but they describe only asmall fractionof our universe

To be honest, we understand very little !
6
kek50th anniversaryauqineu

w

iw
odn

H

iggs

boson

couples todark sector ?

a bit different ?

composite
particle ?

one of many
Higgs particles?

exactly as predictedby today’s theory ?
7

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Higgs decaybranching fractionsas predicted in theStandard ModelHXX
8kek50th anniversarydeviation from Standard
Model prediction [%]Deviations in Higgs couplings
from BSM physics
2HDM-X

Higgs decay mode

new physics @ TeV-scale → few % deviations
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9pMSSM

2HDM-Y

2HDM-X

LHT-6
composite
2HDM-II

arXiv:1708.08912

deviation from Standard
Model prediction [%]Deviations in Higgs couplings
from BSM physics

Higgs decay mode
kek50th anniversary→ different BSM models give different deviations

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pMSSM

2HDM-Y

2HDM-X

LHT-6
composite
2HDM-II

arXiv:1708.08912

deviation from Standard
Model prediction [%]Deviations in Higgs couplings
from BSM physics

precision Higgs measurements → fingerprints of deeper physics
11~1% precision needed for ~TeV new physics
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“Higgs Factory”

based on an electron – positron collider→ high precision measurements ofHiggs particle and other topics

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InternationalLinearCollider

m20 k* electron – positron collider* initial energy:
250 GeV (centre of mass)* initial luminosity: 1.35 x 1034 cm-2 s-1* polarised beams* future upgrades in energy and luminosity~1M Higgs bosons
kek50th anniversary

13International
LinearCollider

m20 k* electron – positron collider* initial energy:250 GeV (centre of mass)* initial luminosity: 1.35 x 1034 cm-2 s-1* polarised beams* future upgrades in energy and luminosity~1M Higgs bosons
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14International
LinearCollider

m20 k* electron – positron collider

why ?

LHC is proton+proton …
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15

proton - proton

protons are composite: quarks and gluons→ wide spectrum of q-q , q-g , g-g collision energies
debris from collision of remainder of protons
dominated by QCD interactions

e+ eelementary particles: each collisions has “fixed” energy
almost no “debris”: clean events, easy to analyse
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dominated by Electro-Weak interactions16

17
kek50th anniversarycross-section [fb]1014

Proton collider

e+ e- collider

108

108

104

104

11
18

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250 ILC 500

International
LinearCollider

m20 k* electron – positron collider* initial energy:
250 GeV (centre of mass)* initial luminosity: 1.35 x 1034 cm-2 s-1* polarised beams* future upgrades in energy and luminosity~1M Higgs bosons
kek50th anniversary

19InternationalLinearCollider

m20 k* electron – positron collider* initial energy:
250 GeV (centre of mass)

why ?

LHC runs at 14 TeV…
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21
kek50th anniversarywhat about this process ?

Hwhat energy is needed ?
22
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International
LinearCollider

m20 k* electron – positron collider* initial energy:
250 GeV (centre of mass)* initial luminosity:
1.35 x 1034 cm-2 s-1* polarised beams* future upgrades in energy and luminosity~1M Higgs bosons
kek50th anniversary

23

InternationalLinearCollider

m20 k* electron – positron collider* initial energy:
250 GeV (centre of mass)* initial luminosity:
1.35 x 1034 cm-2 s-1

what is luminosity?
24
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Number of Higgs bosons= cross-section * integrated luminosity= cross-section * running time * luminosity

need enough luminosity to get enough Higgs bosons in a reasonable time

350 fb = 350 x 10-15 x 10-24 cm2 = 3.5 x 10-37 cm2luminosity: 1.35 x 1034 cm-2 s-1→ 4.7 x 10-3 Higgs s-1→ one Higgs every 3~4 minutes→ 150k per year (if running continuously)(after a few years,plan to upgrade luminosity
to increase this rate)
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25Bunch size

N electrons
Luminosity ~N positrons( repetition rate ) N N ( enhancement factor)
bunch_size (vertical) bunch_size (horizontal)

Large N
Large repetition rate
Small bunch size

~ 1010~ 6500 / s~ 7 nm (vertical) ~ 500 nm (horizontal)
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InternationalLinearColliderm20 k* electron – positron collider* initial energy:
250 GeV (centre of mass)* initial luminosity:
1.35 x 1034 cm-2 s-1* polarised beams* future upgrades in energy and luminosity~1M Higgs bosons
kek50th anniversary

27

InternationalLinearCollider

m20 k* electron – positron collider* initial energy:
250 GeV (centre of mass)* initial luminosity:
1.35 x 1034 cm-2 s-1* polarised beams

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what is beam polarisation ?
what’s good about it ?

28

What is beam polarisation?

mostly positive helicity

mostly negative helicityif highly relativistic:
mostly right-handed

mostly left-handed
29

kek50th anniversaryIn the electro-weak interactions,
Left and Right-handed fermions are different particles

W, ZeL≠

W, ZeR30
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flipping the beam polarisations → 4 different experiments!

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RLLLRRL

R

31

International
LinearCollider

m20 k* electron – positron collider* initial energy:
250 GeV (centre of mass)* initial luminosity:
1.35 x 1034 cm-2 s-1* polarised beams* future upgrades in energy and luminosity
kek50th anniversary

why increase the energy ?

32

topHi ass
gg o cs p iat
rod educti onHiggs production in electron-positron collisions
quWW

fusionwaka
YuarkZZ&500

1000 GeV

Higgs studies can start at 250 GeV

onos gs b lin
g g upHi lf-cose

250

full set of Higgs measurements:
add ~500 & ~1000 GeV
33
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Circular collider (electron-positron)
Energy loss by synchrotron radiation:
power loss ~ E4 / ( m4 r2 )E: energy
m: particle mass
r: ring radius→ practically limits the maximum beam energy→ difficult to increase energy in a ringunless what ?

Electrical power ~ E4

Beam energy limited by tunnel length→ easy to extend (reusing existing tunnel)

Electrical power ~ E

Linear Collider

34
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ILC technology

35
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Key Technology:
Super-Conducting Radio Frequency acceleration

accelerate electrons through 30~35+ million volts every meter36
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37
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Super-Conducting cavities for ILC

Niobium :good superconductor

Super-conductor → dramatically reduce heating→ more efficient38
kek50th anniversarycryomodule~900 for ILC

keep at 2K (–271oC)

room tem
peratureliquid Helium bath

~7,800 for ILC
39
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Superconducting
Test Facility (STF)40
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3 km of “ILC-like” technology
European XFEL @ DESY

cryomodule at FNAL, destined for LCLS-II @ SLAC
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Experiments at ILC

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two international groups developing

detectors for ILC

design detectors with
unprecedented precision→ enable ILC program
challenging requirements
to maximise physics harvest→ efficiency, identification, resolution→ hadronic jet resolution→ angular coveragetechnological advances→ new technologies→ low power, integrated electronics→ compact devices→ machine learning / AI→ quantum sensors
43

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44
kek50th anniversaryGeant4
simulationin ILD detector
45
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tracking detector
precise momentumof charged particles
d pT / pT ~ 3 x 10-5 pT

46
kek50th anniversaryelectromagnetic
calorimeterreasonable precise
measurement ofelectrons, positrons,
photons
dE/E ~ 20% / √E47
kek50th anniversaryhadronic calorimeter
less precise
measurement ofcharged and neutral
hadron energies
dE/E ~ 50% / √E48
kek50th anniversarywhat typeof event ??

49
kek50th anniversary??

50
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@ 250 GeV??

51
kek50th anniversary??

52
kek50th anniversarye+e- → e+e- h [invisible h decay]@ 250 GeV

e+e- → tth [tt → 6q, h → bb]@ 1000 GeV
53

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Higgs-strahlung process is particularly powerful
Higgs can be selected by looking only at Z decay products
we know initial e+e- 4-momentum (at lepton collider)
we precisely measure 4-momentum of Z
→ we can trivially extract 4-momentum of “H”
select Higgs events with no decay mode bias (e.g. invisible Higgs)

Heknow this4-momentume+
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calculate this 4-momentum→ indirectly measure
Higgs massZffmeasure this4-momentum54count total number of produced Higgs events, and extract Higgs mass
without looking at Higgs decay products→ not affected by e.g. unexpectedly weird Higgs decays→ “model independent”
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55many processes willproduce 1 or more
W, Z, H
these usually (~70%)
decay to qq→ shower→ hadronise→ jets56
kek50th anniversaryhadronic jet:charged hadrons

pions, kaons, protons …

photonsfrom pi0, eta, ... decays

neutral hadrons
K0L, neutrons, …

57
kek50th anniversaryhadronic jet:charged hadrons

pions, kaons, protons …
ave. ~65% of energy

photonsfrom pi0, eta, ... decays
ave. ~25% of energy

neutral hadrons

K0L, neutrons, …
ave. ~10% of energy
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how should we measure jet energy ?

58

detector performance requirements
track momentum
impact parametertransparent tracker
jet energy
cover all solid angle around collision59
kek50th anniversaryprecision on Higgs boson couplings based on realistic simulation and analysis
compared to HL-LHC-onlymodel independent fit possible at ILC

arXiv:1903.01629

Higgs coupling to …
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ILC facility
unique e- & e+ beams
high intensity
high energy
high quality→ potential for studies
beyond Higgs,
beyond particle
physics
new ideas welcome !
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Green ILC

linear accelerator and super-conducting technology
were chosen because they minimize energy loss
none the less, ILC operation requires 111 MW (at 250 GeV)
assuming current energy mix: 320 kton CO2 per year
→ continue development of energy saving technologies for ILC→ use of waste energy (heat) by local industry→ encourage and prioritize renewable energy sources→ encourage local forestry industry: wooden construction
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ILC project63
kek50th anniversarymany skilled human resources
extensive production facilities
construction
635.0 − 702.8 GJPY
annual operation 36.6 − 39.2 GJPY

persons

ILC is a large project

Summary of the ILC Advisory Panel's
Discussions to Date after Revision (2018)→ a true international project is essentialyear

IUPAP International Union of Pure and Applied Physics
C11Commission of Particles and Fields

International Committee forFuture Accelerators
International Development Team
kek50th anniversary

S. Henderson
T. Schoerner-Sadenius
K. Jakobs
F. Gianotti
T. Behnke
N. Lockyer
J. Incandela
Z. Huang
I. Koop
V. Obraztsov
Y. Wang
G. TaylorI. Bediaga
S. Krishnagopal
T. Mori
M. Yamauchi
M. Roney
H. Schellman

Chair
Secretary[ECFA chair][CERN DG]

USAGermany
CERN Member States
CERN Member States
CERN Member States[FNAL director]
USAUSAUSA
RussiaRussia[IHEP director]
China
Other Countries
Other Countries
Other Countries
Japan[KEK DG]
Japan
CanadaChair of the IUPAP C-11 (ex officio) 64

ILC project promotion
Tohoku ILC Project
Development Center
local government, industry,
academia

Academia

Federation ofDiet Members
for ILCKEK
Universities
JAHEP
ILC-Japan

ILC

International
Development
Team

ICFA
international
researchers

Advanced
Accelerator
Associationindustry/academia

65
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from late 1980s/’90s → several linear collider studies JLC, GLC, NLC, TESLA, ...
20052013
2020
ILC Global
LinearDesignColliderEffortCollab.
technicalsite-specificdesigndesign~2 yInternl.
Develp.
Team~4 y….

ILC pre-lab.

engineering design
set up ILC lab.
set uppre-laborganisation

~9 y

>20 y

ILC laboratory
construction

operation & upgrades

Strong consensus in world-wide HEP community forelectron-positron Higgs factory (US, Europe, Japan, ...)
ILC is most technologically developed option
Japanese government considering
whether to host ILC in Japan
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candidate ILC site

selected as candidate site byscientists from Japan and abroad
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kek50th anniversary

@Iwate_ilc@ichinoseki_ilc@Oshu_ILC@ILCsupporters@ilc_tsushin@LCNewsLine
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we want!!

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summary
Higgs particle presents a once-per-generation opportunity
to look into our universe’s beginnings, perhaps its destiny
ILC uses technologies developed around the worldtechnologies have been proven
ILC is an ideal facility to enable this study of the Higgs
it requires joint effort from the worldwide community:
governments, local communities, industries, academia
Hosting ILC in Iwate/Japan/Asia will promote position at the forefront ofscience, technology, culture, and society through the 21st century
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