Higgs Factory Workshop - PowerPoint Presentation

Slide1

Higgs

Factory

Workshop

Fermilab

, 14-16

Nov.2012

Slide2

The

Higgs Boson Discovery

4th July 2012Discovered Higgs-like Boson: Clear mass peak in gg and ZZ*4lIs this the SM one ? From searches to measurements

2

November/14/2012

F.Cerutti - Higgs Factory

2

CMS

observed: 6.9;

expected: 7.8

CMS

HCP Nov’

12

Slide3

LHC has

done better than projected:here is a plot from ATLAS in 2005, expected ~4 with 10fb-1 at 14TeV

already measuring couplings at 20% level …(with a number of assuptions)

g

H

-gluon

=ggSM H-gluon

fermion

Vector boson

Photon

HCP 2012 (Kyoto):

-- mass (125.90.4

GeV

/c

2

)

(

my

average

)

-- spin

parity

(0+

preferred

at

2.45 -- CMS)

Slide4

When

mH is known the EW precision measurements have no more freedom! EW precision measurements, rare decays (BS, etc… )-- 4th generation-- SUSY -- Higgs triplets -- etc. etc. Strong incentive to revisit and improve Z pole measurements and mW…

Slide5

Is this the Standard Model Higgs?A Higgs beyond the SM?Measure the properties of this new particle with high precision

The questions

your

Banker’s

question:

What

precision

is

needed

to

see

something

interesting

?

Slide6

Once the

Higgs boson mass is known, the Standard Model is entirely defined. -- with the notable exception of neutrino masses, nature & mixings ***the only new physics there is***but we expect these to be almost completely decoupled from Higgs observables. (true?)

Does H(125.9)Fully accounts for EWSB (W, Z couplings)?Couples to fermions?Accounts for fermion masses?Fermion couplings ∝ masses?Are there others?Quantum numbers?SM branching fractions to gauge bosons?Decays to new particles?All production modes as expected?Implications of MH ≈ 126 GeV?Any sign of new strong dynamics?

your

Banker’s

question:

What

precision

is

needed

to

see

something

interesting

?

Slide7

Some guidance from theorists

New physics affects the Higgs couplingsSUSY , for tanb = 5 Composite Higgs Top partners Other models may give up to 5% deviations with respect to the Standard ModelSensitivity to “TeV” new physics needs per-cent to sub-per-cent accuracy on couplings for 5 sigma discoveryLHC discoveries/(or not) at 13 TeV will be crucial to understand the strategy for future collider projects

R.S. Gupta, H.

Rzehak

, J.D. Wells, “How well do we need to measure Higgs boson couplings?”, arXiv:1206.3560 (2012)

H. Baer et al., “

Physics at the International Linear Collider”, in preparation,

http://lcsim.org/papers/DBDPhysics.pdf

Slide8

The LHC is a Higgs Factory !

1M Higgs already produced – more than most other Higgs factory projects.15 Higgs bosons / minute – and more to come (gain factor 3 going to 13 TeV)Difficulties: several production mechanisms to disentangle and significant systematics in the production cross-sections prod . Challenge will be to reduce systematics by measuring related processes. if observed  prod (gHi )2(gHf)2 extract couplings to anything you can see or produce from H if i=f as in WZ with H ZZ  absoulte normalization

Slide9

Conclusions

Approved LHC 300 fb-1 at 14 TeV:Higgs mass at 100 MeVDisentangle Spin 0 vs Spin 2 and main CP component in ZZ*Coupling rel. precision/Exper.Z, W, b, t 10-15%t, m 3-2 s observationgg and gg 5-11%

9

November/14/2012

F.Cerutti - Higgs Factory

HL-LHC 3000 fb-1 at 14 TeV:Higgs mass at 50 MeVMore precise studies of Higgs CP sectorCouplings rel. precision/Exper. Z, W, b, t, t, m 2-10%gg and gg 2-5%HHH >3 s observation (2 Exper.)Assuming sizeable reduction of theory errors

LHC experiments

entered the

Higgs properties

measurement era:

this is just the beginning !

LHC Upgrade

crucial step towards

precision tests

of the

nature of the newly-discovered boson

Slide10

Couplings at HL-LHC:

ATLAS

MC Samples at 14 TeV from Fast-Sim.Truth with smearing: best estimate of physics objects dependency on pile-up Validated with full-sim. up to m~70Analyses included in ATLAS study:H gg 0-jet and VBFH  tt VBF lep-lep and lep-hadH  ZZ  4lH WW  lnln 0-jet and VBFWH/ZH  ggttH  gg (ttH  mm) Direct top Y couplingH  mm Second generation fermion couplingHH bb gg Higgs Self-Couplings

10

ttH  gg

November/14/2012

F.Cerutti - Higgs Factory

Very

Robust

channel

Good

S

/

B

Statistically limited

Slide11

2030

HL-LHC

will already be a Higgs factory, able to perform precise measurements on the relative values of the

, gluon-gluon,tt, bb, , , W and Z couplings. and even some hint (30% or 3) of Higgs self-coupling.Missing : absolute value of the Higgs total width (or overall strength of couplings) which could play against possible invisible or exotic decay mode in (fortuitous) cancellation. Precision not sufficient for sensitivity to TeV scale in Higgs couplings

2 values of

expected errors: 1. assume same analysis and systematics2. assume theory systematics will reduce by 2 and exp errors as 1/sqrt(N) recall :LEP reduced by factor 10 several theory systematics

2021

Slide12

b





Full HL-LHC

Z

W

H

t

R

elative

Slide13

Higgs Factories Dreams

Slide14

Slide15

 collider

Slide16

Slide17

m+m- Collider vs e+e- Collider ?

A m+m- collider can do things that an e+e- collider cannot doDirect coupling to H expected to be larger by a factor mm/me,jh [speak = 70 pb at tree level]Can it be built + beam energy spread dE/E be reduced to 3×10-5 ?4D+6D Cooling needed!For dE/E = 0.003% (dE ~ 3.6 MeV, GH ~ 4 MeV) no beamstrahlung, reduced bremsstrahlungCorresponding luminosity ~ 1031 cm-2s-1Expect 2300 Higgs events in 100 pb-1/ yearUsing g-2 precession, beam energy and energy spectrumCan be measured with exquisite precision (<100 keV)From the electrons of muon decaysThen measure the detailed lineshape of the Higgs at √s ~ mHFive-point scan, 50 + 100 + 200 + 100 + 50 pb-1Precision from H→bb and WW :

14 Nov 2012

HF2012 : Higgs beyond LHC (Experiments)

17

s

(

m

H

), TLEP

,

W, …

,

W, …

m

H

s

Peak

G

H

0.1 MeV

0.6

pb0.2 MeV10-62.5%5%

√s

s (pb)

[16,17]

Slide18

Neutrino

Factory

MICE

is one of the critical R&D experimentstowards neutrino factories and muon colliders

MICE

MANY CHALLENGES!

MUON COOLING  HIGH INTENSITY NEUTRINO FACTORY HIGH LUMINOSITY MUON COLLIDER

With the growing importance of neutrino physics+ the existence of a light Higgs (125 GeV)physics could be turning this way very fast!

Cooling

and more

generally

the initial

chain

capture,

buncher

, phase rotation and

cooling

rely

on

complex

beam

dynamics

and

technology

,

such

as

High gradient (~>16 MV/m) RF

cavities

embedded

in

strong

(>2T)

solenoidal

magnetic

field

Slide19

Emittance exchange involves ionizationvarying in space which cancels the dispersion of energies in the beam. This can be used to reduce the energy spread and is of particular interest for + -  H (125) since the Higgs is very narrow (~4.2 MeV)

COOLING -- Principle is straightforward…

Longitudinal:

Slide20

Similar to radiation damping in an electron storage ring: muon momentum is reduced in all directions by going through liquid hydrogen absorbers, and restored longitudinally by acceleration in RF cavities. Thus transverse emittance is reduced progressively. Because of a) the production of muons by pion decay and b) the short muon lifetime, ionization cooling is only practical solution to produce high brilliance muon beams

Emittance exchange involves ionizationvarying in space which cancels the dispersion of energies in the beam. This can be used to reduce the energyspread and is of particular interest for + -  H (125) since the Higgs is very narrow (~5MeV)

COOLING --

Principle

is straightforward…

Transverse:

Longitudinal:

Practical

realization is not!

MICE cooling channel (4D cooling)

6D candidate cooling lattices

Slide21

Slide22

The

Higgs

was

barely

missed

at

LEP2

LEP2: 26.7km

circumference

4

IPs

: L3, ALEPH, OPAL DELPHI

20MW of synchrotron radiation (

scales

as E

4

/R)



*

= 5cm



luminosity

lifetime

~ few

hours

L =

10

32

/cm

2

/s H=20%; 240fb

 50

Higgses

per

exp

per

year

!

able to do

discovery

, but not

study

!

What

else

?

Slide23

ILC in a Nutshell

29.10.12

Damping Rings

Polarised electron source

Polarised positron

source

Ring to Main Linac (RTML)

(

inc.

bunch compressors)

e- Main Linac

Beam Delivery System (BDS) & physics detectors

e+ Main Linac

Beam dump

not too scale

Slide24

CLIC Layout at 3 TeV

Drive Beam Generation Complex

Main Beam Generation Complex

140

m

s

train length - 24

 24

sub-pulses

4.2 A - 2.4 GeV – 60 cm between bunches

240 ns

24

pulses –

101 A

– 2.5 cm between bunches

240 ns

5.8

m

s

Drive beam time structure - initial

Drive beam time structure - final

D. Schulte, CLIC, HF 2012, November 2012

Goal: Lepton energy frontier

Slide25

The Higgs at a Linear e+e- Collider has been studied for many yearsCommunity is large and well organized At a given Ecm and Luminosity, the physics has marginally to do with the fact that the collider is linear--specifics: e- (80%) and e+ (30%) polarization is easy at the source for ILC (not critical for Higgs) very small beams  very small beam pipe (b and c physics) pulsed at 5-10Hz  can pulse detector and save on cooling need (X0) Luminosity grows as ECM , 1-2 1034/cm2/s at 500 GeV, one IP. cost grows as A+BECM, both A and B are very large. ‘ready’. 10 years from approval to operation  start 2025… if all goes very well

Latest

reference

:

Slide26

Higgs production mechanism

Assuming that the Higgs is light, in an e+e– machine it is produced by the “higgstrahlung” process close to thresholdProduction xsection has a maximum at near threshold ~200 fb 1034/cm2/s  20’000 HZ events per year.

e

+

e

-

Z*

Z

H

For a Higgs of 125GeV, a centre of mass energy of 240GeV is sufficient  kinematical constraint near threshold for high precision in mass, width, selection purity

Z –

tagging

by

missing

mass

Slide27

best for

tagged

ZH

physics:Ecm= mH+11110 W. Lohmann et al LCWS/ILC2007take 240 GeV.

Slide28

e

+

e

-

Z*

Z

H

Z –

tagging

by

missing

mass

ILC

total rate

 g

HZZ

2

ZZZ final state

 g

HZZ

4

/ 

H



measure

total

width



H

empty

recoil

= invisible

width

‘

funny

recoil

’ =

exotic

Higgs

decay

easy

control

below

theshold

Slide29

New: 250 GeV (HZ) allows to disentangle ambiguity (intrinsic to LHC)between invisible width and total width+precision better to HL-LHC in bb andcchigh energy running allows Hvv channel +access to ttH and HHH…… not better than HL-LHC

Can

we

get sub-% precision  sensitivity to TeV new physics?

Slide30

b





Full HL-LHC

Z

W

H

t

Slide31

How can one increase over LEP 2 (average) luminosity by a factor 500 without exploding the power bill?

Answer is in the B-factory design: a very low vertical emittance ring with higher intrinsic luminosity electrons and positrons have a much higher chance of interacting  much shorter lifetime (few minutes)  feed beam continuously with a ancillary accelerator

Slide32

prefeasibility

assessment

for an 80km

project

at

CERN

John Osborne and Caroline

Waiijer

ESPP

contr

. 165

Slide33

key parameters

LEP3, TLEP(e+e- -> ZH, e+e- → W+W-, e+e- → Z,[e+e-→ t )

 

LEP3TLEPcircumference26.7 km80 kmmax beam energy120 GeV175 GeVmax no. of IPs44 luminosity at 350 GeV c.m.-0.7x1034 cm-2s-1 luminosity at 240 GeV c.m.1034 cm-2s-1 5x1034 cm-2s-1 luminosity at 160 GeV c.m.5x1034 cm-2s-1 2.5x1035 cm-2s-1 luminosity at 90 GeV c.m.2x1035 cm-2s-1 1036 cm-2s-1

at the Z pole repeating LEP physics programme in a few minutes…

10-40 times ILC lumiat ZH thresh.

2-8 times

ILC

lumi

at

ZH

thresh

.

Slide34

Proposal by K. Oide, 13 February 2012

SuperTRISTAN

in Tsukuba: 40 km ring

TLEP tunnel in the KEK area?

Slide35

KEK

12.7 km

80 km ring in KEK area

Slide36

105 km tunnel near FNAL

H. Piekarz

,

“… and … path to the future of high energy particle physics,” JINST 4, P08007 (2009)

(+ FNAL plan B

f

rom

R.

Talman

)

Slide37

What is a (CHF + SppC)

Circular Higgs factory (phase I) + super pp collider (phase II) in the same tunnel

e



e+ Higgs Factory

pp

collider

2012-11-15

HF2012

37

China Higgs Factory (CHF)

Slide38

key parameters

LEP3, TLEP(e+e- -> ZH, e+e- → W+W-, e+e- → Z,[e+e-→ t )

 

LEP3TLEPcircumference26.7 km80 kmmax beam energy120 GeV175 GeVmax no. of IPs44 luminosity at 350 GeV c.m.-0.7x1034 cm-2s-1 luminosity at 240 GeV c.m.1034 cm-2s-1 5x1034 cm-2s-1 luminosity at 160 GeV c.m.5x1034 cm-2s-1 2.5x1035 cm-2s-1 luminosity at 90 GeV c.m.2x1035 cm-2s-1 1036 cm-2s-1

at the Z pole repeating LEP physics programme in a few minutes…

10-40 times ILC lumiat ZH thresh.

2-8 times

ILC

lumi

at

ZH

thresh

.

Slide39

Circular

machine

revisited

after

super-b

and synchrotron light source:

e.g

. TLEP



sub

%

precision

and

sensitivity

to

TeV

-

scale

physics

.

Slide40

gHZ

gHb gHc gHg gHW gH gH gH H H,inv

Slide41

key parameters

LEP3, TLEP(e+e- -> ZH, e+e- → W+W-, e+e- → Z,[e+e-→ t )

 

LEP3TLEPcircumference26.7 km80 kmmax beam energy120 GeV175 GeVmax no. of IPs44 luminosity at 350 GeV c.m.-0.7x1034 cm-2s-1 luminosity at 240 GeV c.m.1034 cm-2s-1 5x1034 cm-2s-1 luminosity at 160 GeV c.m.5x1034 cm-2s-1 2.5x1035 cm-2s-1 luminosity at 90 GeV c.m.2x1035 cm-2s-1 1036 cm-2s-1

a

t the

Z

pole repeating LEP physics programme in a few minutes…

Slide42

Circular e+e Collider as a Higgs Factory

Advantages: At 240 GeV, potentially a higher luminosity to cost ratio than a linear oneBased on mature technology and rich experience Some designs can use existing tunnel and siteMore than one IPTunnel of a large ring can be reused as a pp collider in the futureChallenges: Beamstrahlung limiting beam life time requires lattice with large momentum acceptance RF and vacuum problem from synchrotron radiation A lattice with low emittance Efficiency of converting wall power to synchrotron radiation powerLimited energy reachNo comprehensive study; design study needed.

42

ICFA workshop on

Higgs

Factories

,

Fermilab

14-16-

November

2012

Slide43

beamstrahlung: reducing * and increasing current leads to radiation of particlesin the field of the colliding bunch.  increase energy spread and produce tails

LEP3

beamstrahlung more benign than for linear collider

M. Zanetti (MIT)

luminosity

spectrum

LEP3

& ILC:

Slide44

circular HFs – beamstrahlung

t

>2 s at h=1.0% (4 IPs)t>37 s at h=1.5%t>11 min at h=2.0% t>3h at h=2.5%

simulation w 360M macroparticles t varies exponentially w energy acceptance hpost-collision E tail → lifetime t

TLEP at 240 GeV:

M. Zanetti (MIT)

t

>6 s at

h=2.0% (4 IPs)t>37 s at h=2.5%t>3 min at h=3.0% t>20 min at h=3.5%

TLEP at 350 GeV:

Slide45

1. LEP3 (C=27km) is limited to the ZH threshold at 240 GeV + complicated (and unlikely) to integrate in the LHC tunnel  keep it as backup if all else fails 2. TLEP (C=80km) is the favorite: superb physics performance, revisit all EW energy scale 90-370 GeV. with up to 4 collision points 80km ring e+e- collider can be 1st step to O(100 TeV) pp collider, and ~100GeV<-> 50 TeV ep collider thereby offering long term vision at CERN 3. linear machines can be upgraded to energies up to ~1 or even 3 TeV (upgrade path from ILC to CLIC in same tunnel has been discussed) 4. A muon collider remains the most promising option for the very high energy exploration with point-like particles.

Extension

possibilities

Slide46

PSB

PS (0.6 km)

SPS (6.9 km)

LHC (26.7 km)

TLEP (80 km,

e

+

e

-, up to ~370 GeV c.m.)

VHE-LHC (pp, up to 100 TeV c.m.)same detectors?

a

lso: e± (100 GeV) – p (7 & 50 TeV) collisions

possible long-term strategy

≥50 years of e+e-, pp, ep/A physics at highest energies

(E. Meschi)

Zimmermann

Slide47

all of

this

is

for TLEP/VHE-LHC

Slide48

Conclusions

-- The

newly

discovered

H(126) candidate

is

a

fascinating

particle

of a new nature (

elementary

scalar

!)

that

deserves

detailed

measurements

-- There

is

much

more to

understand

about

Higgs

physics

measurements

and

their

potential

to test

physics

beyond

the SM. This

should

be

discussed

in a

dedicated

and

detailed

Higgs

Physics

workshop.

-- LHC

is

/

will

be

an impressive

Higgs

factory

.

This must

be

taken

into

account

in

any

future machine discussion!

-- The

linear

collider

ILC

can

perform

measurements

at

few%

level

for the

Higgs

invisible

width

,

search

for

exotic

decays

, and

improvement

of

bb

, cc,

couplings

wrt

LHC by

factors

~2

-- for

,

,

,

ttH

, HHH, HL-LHC

will

do ~ as

well

or

better

-- There

is

a

strong

motivation to

investigate

if one

could

do

better

-- more

precise

or/and

cheaper

--

Now

that

the

Higgs

mass

is

known

, a new round of

precision

EWRC

measurements

is

strongly

motivated

. (

Predicted

m

top

,

m

Higgs

,

now

sensitive

inclusively

to EW-

coupled

new

physics

)

Slide49

-- e+e- ring collider offer a potentially better luminosity/cost ratio than the linear one and the possibility to have several IPs. -- Much progress has been brought about by the experience of LEP2 B factories and Synchrotron light sources.-- The main point of the HF2012 workshop was to understand whether the performance of circular machines could be as high as advertised The answer is ‘maybe’ but there is lots of work to do to establish this.There are also ideas to push the luminosity further.This calls for a design study of circular e+e- Higgs Factory -- If the luminosities advertised can be reached, the resolutionson several Higgs couplings can be improved from a few % to below percent precisions, opening the possibility of discovery of TeV scale new physics. -- Revisiting Z pole and W threshold is now a must. This can be done at both circular machines with extreme precision using the virtues of excellent calibration and polarization.

Conclusions(2)

Slide50

Slide51

Slide52

TLEP design study –preliminary structurefor discussion

Physics

Experiments

Accelerator

1. Theoretical implications and model building2. Precision measurements, simulations and monte-carlos3. Combination + complementarity with LHC and other machines ; global fits

1. H(126) properties2. Precision EW measurements at the Z peak and W threshold3. Top quark physics4. Experimental environment5. Detector design6. Online and offline computing

1. Optics, low beta, alignment and feedbacks2. Beam beam interaction3. Magnets and vacuum 4. RF system5. Injector system6. Integration w/(SHE)-LHC7. Interaction region8. Polarization &E-calib.9. Elements of costing

Steering group web site, mailing lists, speakers board, etc..

International Advisory board

Institutional board

Slide53

CONCLUSIONS(3)

With

the

discovery

of H(126) a new

chapter

is

open in

Particle

physics

. It

will

take

a long time and

should

be

planned

carefully

.

Depending

on the

outcome

of LHC

run

at

14

TeV

, a

dedicated

machine to

study

with

great

precision

the

Electroweak

scale

90-350

GeV

,

will

be

very

strongly

motivated

.

A

n e+e-

collider

situated

in a new 80km tunnel,

offers

outstanding

luminosity

and

precision

.

It

can

serve as a

precursor

for a

high

energy

exploratory

pp machine

at

~100

TeV

There are

many

challenges! A design

study

has been

recommended

and

you

are

very

welcome

to

participate

https://espace.cern.ch/LEP3/