rey.hori / KEK

Experiments at the International Linear Collider

Daniel Jeans (IPNS/KEK)ICS2024@APPI

February 2024

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

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

4
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 spin5
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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 ?

is our current vacuum
really stable ?
might the vacuum in our universe
spontaneously decay ?

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

To be honest, we understand very little !
7
kek50th anniversaryauqineuw

iw
odn

Higgs

boson

couples todark sector ?

a bit different ?

composite
particle ?

one of manyHiggs particles?

exactly as predictedby today’s theory ?
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Higgs decaybranching fractionsas predicted in theStandard ModelHXX

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Higgs couples to particles’ mass9deviation from Standard
Model prediction [%]Deviations in Higgs couplings
from BSM physics
2HDM-X

Higgs decay mode

new physics @ TeV-scale → few % deviations 10
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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

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

11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
12~1% 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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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

14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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15International
LinearCollider

m20 k* electron – positron collider

why ?

LHC is proton+proton …
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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 “strong force” QCD interactions

e+ eelementary particles: each collision has “fixed” energy
almost no “debris”: clean events, easy to analyse
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dominated by Electro-Weak interactions17

18
kek50th anniversarycross-section [fb]1014

Proton collider

e+ e- collider

108

108

104

104

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250 ILC 500

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

20International
LinearCollider

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

why ?

LHC runs at 14 TeV…
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22
kek50th anniversarywhat about this process ?

Hwhat energy is needed ?
23
kek50th anniversarywhat about this process ?
hint: mass of H boson is 125 GeVHwhat energy is needed ?
24
kek50th anniversarywhat about this process ?

H

why is this not so useful ?
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hint: Higgs couples to particles’ mass

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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

26

International
LinearCollider

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?
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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 cm2
ILC luminosity: 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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Bunch size

N electrons
Luminosity ~N positrons
N * N * ( repetition rate ) * ( 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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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

30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

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

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What is beam polarisation?

mostly positive helicity

mostly negative helicity

if highly relativistic:
mostly right-handed

mostly left-handed
32

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

W, ZeL≠

W, ZeR33
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flipping the beam polarisations → 4 different experiments!

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RLLLRRLR34

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
kek50th anniversary

why increase the energy ?

35

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

fusionwakaYuarkZZ&500

1000 GeV

Higgs studies can start at 250 GeV

onos gs b lin
g g upHi lf-co
se250

full set of Higgs measurements:
add ~500 & ~1000 GeV
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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 ~ E4Beam energy limited by tunnel length→ “easy” to extend (reusing existing tunnel)

Electrical power ~ E

Linear Collider

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ILC technology

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Key Technology:
Super-Conducting Radio Frequency acceleration

accelerate electrons through 30~35+ million volts every meter39
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40
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Super-Conducting cavities for ILC

Niobium :good superconductor

Super-conductor → dramatically reduce heating→ more efficient41
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cryomodule~900 for ILC

keep at 2K (–271oC)

room tem
peratureliquid Helium bath

~7,800 for ILC
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Superconducting
Test Facility (STF)43
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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 sensors47

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48
kek50th anniversaryGeant4 simulationin ILD detector49
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tracking detector
precise momentumof charged particles
d pT / pT ~ 3 x 10-5 pT50
kek50th anniversaryelectromagnetic
calorimeterreasonable precise
measurement ofelectrons, positrons,photons
dE/E ~ 20% / √E51
kek50th anniversaryhadronic calorimeter
less precise
measurement ofcharged and neutral
hadron energies
dE/E ~ 50% / √E52
kek50th anniversarywhat typeof event ??

53
kek50th anniversary??

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@ 250 GeV??

55
kek50th anniversary??

56
kek50th anniversarye+e- → e+e- h [invisible h decay]@ 250 GeV

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

measure this4-momentum

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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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59many processes willproduce 1 or more
W, Z, H
these usually (~70%)
decay to qq→ shower→ hadronise→ jets60
kek50th anniversaryhadronic jet:charged hadrons

pions, kaons, protons …

photonsfrom pi0, eta, ... decays

neutral hadrons
K0L, neutrons, …

61
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 ?

62detector performance requirements
track momentum
impact parametertransparent tracker
jet energy
cover all solid angle around collision63
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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kek50th anniversaryproposed Higgs factory projects

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ILC project68
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'sDiscussions to Date after Revision (2018)year→ a true international project is essential
IUPAP International Union of Pure and Applied Physics
C11Commission of Particles and Fields

International Committee forFuture Accelerators
International Development Team
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P. Campana
T. Schoerner-Sadenius
P. Sphicas
F. Gianotti
B. Heinemann
L. Merminga
S. Dasu
N. RoeI. Koop
V. Obraztsov
Y. Wang
U. Egged
G. Gil da Silveira
T. Nagoya
M. Yamauchi
R. Teuscher
F. Canelli

Chair
Secretary[ECFA chair][CERN DG]

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

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

Academia

Federation ofDiet Members
for ILCILC-Japan
KEK
Universities
JAHEP

ILC

International
Development
Team

ICFA
international
researchers

Advanced
Accelerator
Associationindustry/academia

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from late 1980s/’90s → several linear collider studies JLC, GLC, NLC, TESLA, ...
2005

2013
2020
ILC Global
LinearDesignColliderEffortCollab.
technical
site-specificdesigndesign~4 yInternl.
Develp.
TeamILC pre-lab.

engineering design
set up ILC lab.
set up

~9 y

>20 y

ILC laboratory
construction

operation & upgrades

pre-laborganisation

Strong consensus in world-wide HEP community forelectron-positron Higgs factory (US, Europe, Japan, ...)
Several Higgs Factory proposals

ILC is most technologically developed option

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Japanese government considering
whether to host ILC in Japan71

candidate ILC site

selected as candidate site byscientists from Japan and abroad
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@Iwate_ilc@ichinoseki_ilc@Oshu_ILC@ILCsupporters@ilc_tsushin@LCNewsLine
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we want!!

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summaryHiggs particle presents a once-per-generation opportunity
to look into our universe’s beginnings, perhaps its destiny(most) particle physicists agree it would be great to have a “Higgs Factory”
several such projects under consideration
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
ILC uses technologies developed around the worldtechnologies have been proven
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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