fabiola gianotti, gruppo 1, 25/3/20021 gruppo 1, 25/3/2002 fabiola gianotti (cern) physics at cern...

Fabiola Gianotti, Gruppo 1, 25/3/2002 1

Gruppo 1, 25/3/2002

Fabiola Gianotti (CERN)Fabiola Gianotti (CERN)

Physics at CERN after thePhysics at CERN after the LHC LHC

• The coming years : news from last week …• Options for future machines• LHC upgrade and CLIC: machines, experiments, physics potentials• Muon Collider and storage ring (low priority … )• Post-LHC physics scenarii• Conclusions


Outline of Savings Plan 2002-2009Outline of Savings Plan 2002-2009

Item CERN money saving (MCHF)

Industrial services, contracts 170 Fellows and associates 41Research program (SPS cuts, OPERA) 30Accelerator R&D 13 Austerity measures 75LHC computing 60 Energy (cryogenics, SPS cuts) 60

Total 449

SPS and PS running : -- running time reduced by 30% in 2003, 2006 -- SPS shut-down in 2005 R& D for future accelerators: -- CLIC (CTF3) : budget is ~ 4.5 MCHF per year -- others (e.g. factory) : ~ no financial support Minimal / narrow program for lab like CERN, only justified by critical situation (e.g. accelerator R&D is few % of total budget at SLAC, DESY, FNAL)


NEW LHC SCHEDULENEW LHC SCHEDULE Last dipole : July 2006Last dipole : July 2006Machine closed and cooled down : October 2006Machine closed and cooled down : October 2006First beams : April 2007First beams : April 2007Physics : July 2007 Physics : July 2007

CNGS : - starts in 2006 - has to stay within budget - review ongoing


Which machine after the LHC ? Which machine after the LHC ?

Motivation : physics beyond the Standard Model Indeed : LHC will not answer all questions. E.g. can discover SUSY but full understanding of new theory most likely requires measurements at a complementary machine

However : -- physics scenario beyond SM not known …. although LEP EW data (light Higgs) favour weak EWSB like in SUSY and disfavour composite Higgs of strongly-interacting models -- unlike for TeV-scale, no compelling motivation today for >> TeV-scales

Difficult to take decision today but some answers / clues from LHC data

Need vigorous accelerator and detector R & D to be able to take decision by 2010


Possible options for future machines

LHC upgrade : luminosity (L = 1035 cm-2 s-1 ), maybe energy (s = 28 TeV ? )

TeV-range e+e- LC (TESLA, NLC, JLC) : s = 0.5 –1.5 TeV, L = 1034 cm-2 s-1

multi-TeV e+e- LC (CLIC) : s = 3-5 TeV, L = 1035 cm-2 s-1

Muon Collider : s 4 TeV, L ~ 1034 – 1035 cm-2 s-1 ?

Three steps : factory, Higgs factory, high-E muon collider

VLHC : s = 100-200 TeV, L = 1034 - 1035 cm-2 s-1

time scale 2020

time scale > 2020

ring ~ 230 Km

and are most likely not CERN options has low priority given present “crisis”

Here : ~ only and are discussed


LHC upgradeLHC upgrade

• Discussions started in Spring 2000 : -- luminosity upgrade to L = 1035

-- s = 28 TeV ? more difficult/expensive than L upgrade

• 2 WG set up by CERN DG in Spring 2001 :

-- physics and detectors (convened by M.Mangano, J.Virdee, F.G.) final report ~ ready : “ Physics potential and experimental challenges of the LHC luminosity upgrade ” -- machine (convened by F.Ruggiero) final report in preparation : “ LHC luminosity and energy upgrades : a feasibility study ”

• Motivations : -- maximum exploitation of existing tunnel, machine, detectors … -- LHC may give hints for New Physics at limit of sensitivity -- improve / consolidate LHC discovery potential and measurements


From preliminary feasibility studies :

• L upgrade to 1035: -- increase bunch intensity to beam–beam limit L ~ 2.5 x 1034

-- halve bunch spacing to 12.5 ns (new RF) -- change inner quadrupole triplets at IP1 , IP5 halve * to 0.25 m

Other options : upgrade injectors to get more brilliant beams, single 300 m long super-bunch, etc.

• s upgrade to 28 TeV : -- ultimate LHC dipole field : B= 9 T s = 15 TeV any energy upgrade requires new machine -- present magnet technology up to B ~ 10.5 T small prototype at LBL with B= 14.5 T -- magnets with B~16 T may be reasonable target for operation in ~ 2015 provided intense R& D on e.g. high-temperature superconductors (e.g. Nb3Sn)

moderatehardware changestime scale 2012 ?

majorhardware changestime scale 2015 ?


s = 28 TeV upgradeL = 1035 upgrade“SLHC = Super-LHC”

vsvs

Easier for machine Challenging and expensive for machine

Major changes to detectors for Modest changes to detectors full benefit, very difficult environment

Smaller physics potential: Larger physics potential:-- mass reach 20-30% higher than LHC -- mass reach ~1.5 higher than LHC -- precision measurements possible but -- many improved measurements (e.g. Higgs) -- with significant detector upgrades -- higher statistics than LHC -- challenging due to environment -- LHC-like environment

If both : s = 28 TeV + L =1035 : LHC mass reach extended by ~ 2

Here : mainly potential of L upgrade (but comparison with s = 28 TeV available in some cases)

Assumptions : -- L dt = 1000 fb-1 per experiment per year of running -- similar ATLAS and CMS performance as at LHC somewhat optimistic (but performance deterioration not dramatic)


L = 10L = 103535 : experimental challenges and detector upgrades : experimental challenges and detector upgrades

• If bunch crossing 12.5 ns LVL1 trigger (BCID) tracker (occupancy)

must work at 80 MHz

• ~ 120 minimum-bias per crossing (compared to ~ 25 at LHC)• occupancy in tracker ~ 10 times larger than at LHC (for same granularity and response time)• pile-up noise in calorimeters ~ 3 times larger (for same response time)

• radiation :

R (cm) hadron fluence Dose (kGy) 1014 cm-2

4 30/190 840/500011 5/28 190/113022 1.5/10 70/42075 0.3/2 7/40 115 0.2/1 2/11

CMS tracker

ECAL dose HCAL dose (kGy) (kGy)

0-1.5 3/18 0.2/1 2.0 20/120 4/252.9 200/1200 40/2503.5 100/600 5 1000/6000

CMS calorimeters

—— 500 fb-1 = ~ 10 years at LHC—— 3000 fb-1 = ~ 3 years at SLHC

1 Gy = 1 Joule/Kg


• Trackers : need to be replaced (radiation, occupancy, response time) -- R > 60 cm : development of present Si strip technology ~ ok -- 20 < R < 60 cm : development of present Pixel technology ~ ok -- R < 20 cm : fundamental R & D required (materials, concept, etc.) -- channel number ~ 5 larger (occupancy) R&D needed for low cost

• Calorimeters : mostly ok -- ATLAS : space-charge problems in LAr fwd calorimeter -- CMS : -- radiation resistance of end-cap crystals and electronics ? -- change scintillator or technique in hadronic end-cap -- plastic-clad quartz-clad quartz fibers in fwd calorimeter

• Muon spectrometers : mostly ok -- increase forward shielding acceptance reduced to ||< 2 -- space charge effects, aging ? -- some trigger chambers (e.g. ATLAS TGC) too slow for 12.5 ns

• Electronics and trigger : large part to be replaced -- new LVL1 trigger electronics for 80 MHz -- R&D needed for e.g. tracker electronics (fast, rad hard) -- most calorimeter and muon electronics ~ ok (radiation resistance ?)


• EM calorimeter energy resolution:

e ET= 30 GeV

3410at % 2.5 E

3510at % 3.6 E

- deterioration smaller at higher E ( pile-up ~ 1/E)

- pessimistic : optimal filtering could help

Examples of (ATLAS) performance at 10Examples of (ATLAS) performance at 1035 35

• e/jet separation:

L (cm-2 s-1) Electron efficiency Jet rejection 1034 81% 10600 22001035 78% 6800 1130

ET = 40 GeV

• b-tagging:

(GeV) 1034 1035

30-45 33 3.7 60-100 190 27100-200 300 113200-350 90 42

pTRejection against u- jets for 50% b-tagging efficiencyassuming same 2-track resolution at 1035 as at 1034

Full Geant simulationNo optimisation done

deterioration smaller at higher E


Compact LInear Collider s = 3 5 TeV, L = 1035

Two-beam acceleration : main beam accelerated by deceleratig high-intensity drive beam

• Gradient ~ 150 MV/m, RF = 30 GHz length < 40 Km• Bunch spacing < 1 ns• Test facilities CTF1 and CTF2 : -- two-beam principle demonstrated -- 150 MV/m achieved with 3 ns bunch trains• CTF3 (2002-2006) : to demonstrate 150 MV/m with 100 ns bunch trains

Spring 2000 : CLIC Physics study group set up (convened by A. De Roeck)


Challenging experimental environment

• High intensity beams strong beam-beam interactions

-- distortion of luminosity spectrum-- backgrounds (e.g. e+e- pairs) high B-field, trackers at R > 3 cm fwd mask < 70

• Pile-up : -- bunch x-ing < 1 ns -- ~ 4 hadrons Evis > 5 GeV per x-ing s (TeV) 1 3 5

L in 1% s 56 % 30% 25%L in 5% s 71 % 42% 34%TESLA-like detector under study:

3-15 cm Si VDET15-80 cm Si central/ forward disks80-230 cm TPC or Si tracker240-280 cm ECAL 280-400 cm HCAL 400-450 cm Coil (4T)450-800 cm Fe/muon

Event rates/year 3 TeV 5 TeV 1000 fb-1 103 evts 103 evts

e+e- tt 20 7e+e- bb 11 4e+e- ZZ 27 11e+e- W+W- 490 205e+e- H (120 GeV) 530 690e+e- H+H- (1 TeV) 1.5 1e+e- (1 TeV) 1.3 1

~~

“ beamstrahlung”

Need flavour tagging, calo granularity, etc.Need flavour tagging, calo granularity, etc.But what about E-flow for high-E jets ? But what about E-flow for high-E jets ?


Physics potentials of the upgraded LHC and CLIC …. a few examples …

Examples of SM measurements :

-- Triple Gauge Couplings -- Multi gauge boson production -- Rare top decays

Note : all results are preliminary ….

Note : most of SM physics program (W-mass, top physics, etc.) will be completed at standard LHC. However : rate-limited processes can benefit from SLHC


Triple Gauge Bosons at LHC and SLHC W W

, Z

Probe non-Abelian structure of SU (2) and sensitive to New Physics

, k from W Z , kZ , g1

Z from W Z =e, 1034

= 1035

-couplings increase as ~ s constrained by tot, high-pT tails

k-couplings : softer energy dependence constrained mainly by angular distributions

Expected precision from LEP2 + Tevatron in 2007 : %


95% C.L. constraints for 1 experiment

14 TeV 14 TeV 28 TeV 28 TeV100 fb-1 1000 fb-1 100 fb-1 1000 fb-1

1.4 0.6 0.8 0.2Z 2.8 1.8 2.3 0.9k 34 20 27 13kZ 40 34 36 13g1

Z 3.8 2.4 2.3 0.7

(units are 10-3 ), = 10 TeV

from fits to tot, pT , pT

Z

Z

kZ

Z

14 TeV 100 fb-1 28 TeV 100 fb-1 14 TeV 1000 fb-1 28 TeV 1000 fb-1

SLHC sensitivity to , Z, g1Z at level of SM radiative corrections

Angular distributions not used pessimistic for k-couplings

These SLHC results do not require major detector upgrades : only high-pT muonsand photons used here (assuming trackers not replaced)


Comparison with TESLA and CLIC

W+

W-, Ze+

e-

Anomalous contributions depend on scale of New Physics no limit to desired precision

e.g.

SLHCSLHC

SLHCSLHC

((revised version of a figure by T. Barklow)


Multiple gauge boson production at SLHCMultiple gauge boson production at SLHC

W+

W- Z*q

q

Z

q

q

q

q

W Z

ZWZ

- Probe quartic anomalous couplings (e.g. 5-ple vertex = 0 in SM) - Rate limited at LHC

Process Expected events after cuts 6000 fb-1

WWW 2600WWZ 1100ZZW 36ZZZ 7WWWW 5WWWZ 0.8

W Z = e,

LHC sensitive to some4-ple vertices

SLHC may be sensitive to 5-ple vertex

Not yet studied at CLIC …


FCNC top decays at SLHC t c,u

, Z, g

• Most measurements (e.g. mtop ~ 1.5 GeV) limited by systematics ~ no improvement at SLHC

• Exception : FCNC decays Some theories beyond SM (e.g. some SUSY models, 2HDM) predict BR 10-5- 10-6, which are at the limit of the LHC sensitivity

• Expected limits from Tevatron Run II in 2007 : BR < 10-3

CLIC : no sensitivity (~ 20 000 tt pairs/year)

Channel LHC SLHC (600 fb-1) (6000 fb-1)

t q 0.9 0.25t qg 61 19t qZ 1.1 0.1

99% C.L. sensitivity to FCNC BR (units are 10-5)

only possible if b-taggingperformance at SLHC similar to LHC


Examples from Higgs physics :

-- Higgs couplings to fermions and bosons -- Higgs self-couplings -- Rare decay modes -- MSSM Higgs sector -- Strongly-interacting Higgs

Note : -- Higgs search/discovery program will be completed at standard LHC-- Higgs physics at SLHC requires new trackers (b-tagging, e measurements, etc.) in most cases


Higgs couplings to fermions and bosons gHff

Can be obtained from measured rate in a given production channel:

ff) H( BR X)H pp ,e(e dt L R -ff ff) (H BR

tot

f

deduce f ~ g2Hff

• LC : tot and (e+e- H+X) from data • LHC : tot and (pp H+X) from theory without theory inputs measure ratios of rates in various channels (tot and cancel) f/f’

ZZ H

H

ZZ H

WW H

ttbb ttH

tt ttH

qq qqH

qqWW qqH

WW H

WWW WH

H

X WH

Closed symbols: LHC 600 fb-1

Open symbols:SLHC 6000 fb-1

Improvement in precision by up to ~ 2 from LHC to SLHCHowever : not competitive with TESLA and CLIC precision of %


Higgs self-couplings at SLHC

Higgs potential : 4322 λH4

1 vH H v ~ V

~ 3v

mH2 = 2 v2

probe HHH vertex via double H production

LHC : (pp HH) < 40 fb mH > 110 GeV + small BR for clean final states no sensitivity

SLHC : HH W+ W- W+ W- jj jj studied (very preliminary)

S B S/B S/B

mH = 170 GeV 350 4200 8% 5.4mH = 200 GeV 220 3300 7% 3.8

6000 fb-1 Backgrounds (e.g. tt)rejected with b-jet vetoand same-sign leptons

If : -- KB2 < KS

-- B can be measured with data + MC (control samples) -- B systematics < B statistical uncertainty -- fully functional detector (e.g. b-tagging)

-- -- HH production may be observed at SLHC-- may be measured with stat. error ~ 20%


Higgs self-couplings at CLIC-

mH=120 GeV, 4b final states

TESLA : 25% precision 1000 fb-1

CLIC : 7 % precision 5000 fb-1

5000 fb-1


Higgs rare decays

Signal significance S/Signal significance S/B :B :LHC LHC (600 fb-1) ~ 3.5 ~ 3.5 SLHC SLHC (6000 fb-1) ~ 11 ~ 11

H H Z Z

Signal significance S/Signal significance S/B :B :LHC LHC (600 fb-1) ~ 3.5 ~ 3.5 (gg+VBF)

SLHC SLHC (6000 fb-1) ~ 7 ~ 7 (gg)

H H m mHH=130 GeV=130 GeV

Additional coupling measurement:gH to ~ 15%

BR (H BR (H ) ~ 10) ~ 10-4-4 SM SM


CLIC, 5000 fb-1

gH to ~ 5%

Higgs rare decays

Signal significance S/Signal significance S/B :B :LHC LHC (600 fb-1) ~ 3.5 ~ 3.5 SLHC SLHC (6000 fb-1) ~ 11 ~ 11

H H Z Z

Signal significance S/Signal significance S/B :B :LHC LHC (600 fb-1) ~ 3.5 ~ 3.5 (gg+VBF)

SLHC SLHC (6000 fb-1) ~ 7 ~ 7 (gg)

H H m mHH=130 GeV=130 GeV

Additional coupling measurement:gH to ~ 15%

BR (H BR (H ) ~ 10) ~ 10-4-4 SM SM


MSSM Higgs sector : h, H, A, H

5 contours, decays to SM particles

In the green region onlySM-like h observable, unlessA, H, H SUSY particles LHC can miss part of MSSM Higgs sector

For mA < 600 GeV, TESLA can demonstrate indirectly (i.e. through precision measurements of h properties) existence of heavy Higgs bosons at 95%C.L.

Region where 1 heavy Higgs observableat SLHC green region reduced by up to 200 GeV + region accessible directly or indirectly to TESLA fully covered

600 fb-1

6000 fb-1

mh < 130 GeVmA mH mH


CLIC : sensitive to m (A, H, H ) up to 1 TeV

full MSSM Higgs spectrum should be observed

H+

H-, Ze+

e-e.g. H+H- production

H tb Wbb jjbb 8 jets final state

3000 fb-1

ttbbbackgound

mm ~ 4% ~ 4%


Strong VL VL scattering at LHC, SLHC

If no Higgs, expect strong VLVL scattering (resonant or non-resonant) at TeV s

q

q

q

q

VL

VL

VL

VL LHC : fbForward jet tag and central jet vetoessential tools against background

Fake fwd jet tag probability frompile-up (preliminary ..)

ATLAS full simulation

LHC may observe only non-resonant WLWL WLWL

More channels, e.g. WLZL WLZL , ZLZL ZLZL , may be observed at SLHC more clues to underlyingdynamics

Need new trackers (e.g. charge measurement)

~ 280 GeV

Pile-up included


Strong VL VL scattering at CLIC

Observation of strong EWSB not granted at LHC, SLHC: -- only fully leptonic final states accessible tiny rates -- non-resonant WLWL : same shapes for signal and background -- relies on fwd jet tag and jet veto performance observation depends on model parameters

Measurement of resonance parameters at CLIC under study (beam polarisationis additional tool) strong dynamic should be explored in detail

CLIC : -- ~ 4000 events/year at production for m = 2 TeV, = 85 GeV -- fully hadronic final states accessible -- small backgrounds

observation of resonant and non-resonant scattering up to ~ 2.5 TeV in several models

W jj

W jj

W, Z massresolution ~7%(collimated jets)

E.g. expected significance for non-resonant WLWL WLWL :LHC (300 fb-1) ~ 5 SLHC (3000 fb-1) ~ 13 K-matrix unitarization modelCLIC (1000 fb-1) ~ 70


Examples of Physics beyond the SM :

-- SUSY -- Extra-dimensions -- Z ’ -- Compositeness


SUSY at LHC, SLHC

CMS

tan=10

5 contours

• If SUSY connected to hierarchy problem, some sparticles should be observed at LHC• However: no rigorous upper bound may be at limit of sensitivity e.g. inverted hierarchy models : up to several TeV first two generations• Expected limits from Tevatron Run II in 2007 :

g~ ,q~

)q~( mGeV 400 )g~( m ),q~( m

LHC 2.5 TeVSLHC 3 TeVs = 28 TeV, 1034 4 TeV s = 28 TeV, 1035 4.5 TeV

5 discovery reach on )g~( m ),q~( m

-- No major detector upgrade needed for discovery : inclusive signatures with high pT calorimetric objects-- Fully functional detectors (b-tag, etc.) needed for precision measurements of SUSY parameters based on exclusive chains (some are rate-limited at LHC)


SUSY at CLICSUSY at CLIC Sensitive to ~ all sparticles up to m ~ 1.5-2.5 TeV

• can complete SUSY spectrum: some sparticles not observable at LHC (small S/B) nor at TESLA (if m > 200-400 GeV)• precision measurements (e.g. masses to 0.1%, field content) constrain theory parameters

Examples of mSUGRA pointscompatible with present constraints

M1

M2

M3 = )~( m g

(from LHC)

Blair, Porod, Zerwas

EW RGE GUT

from precisemeasurements of e.g. gaugino masses at EW scale reconstructtheory at high E

mm1/21/2


Extra-dimensions

Several models studied :

ADD ( Arkani-Hamed, Dimopoulos, Dvali) : direct production or virtual exchange of a continuous tower of gravitons

RS ( Randall-Sundrum) : graviton resonances in the TeV region

TeV-1 scale extra-dimensions : resonances in the TeV region due to excited states of SM gauge fields


Arkani-Hamed, Dimopoulos, Dvali

If gravity propagatesin 4 + dimensions, a gravity scale MD 1 TeV is possible

MPl2 MD

+2 Rr

1

M

1 ~ (r) V 2

Pl

4

r

1

R M

1 ~ (r)V 2

D

4 at large distance

SM wall

Bulk

G

G

• If MD 1 TeV : = 1 R 1013 m excluded by macroscopic gravity = 2 R 0.7 mm limit of small- scale gravity experiments …. = 7 R 1 Fm

Extra-dimensions are compactified over R < mm R


• Gravitons in Extra-dimensions get quantised mass:

... 1,k R

k ~ m k

3 eV 400 m e.g. R

1 ~ m

continuous tower of massive gravitons(Kaluza - Klein excitations)

N M

1 kk2

Pl

Gf

f

2DM

s

R s M

1

m

s

M

1 2

Pl2

Pl

• Only one scale in particle physics : EW scale• Can test geometry of universe and quantum gravity in the lab

Due to the large number of Gkk , the couplingSM particles - Gravitons becomes of EW strength


Supernova SN1987A cooling by emission (IBM, Superkamiokande) bounds on coolingvia Gkk emission: MD > 31 (2.7) TeV = 2 (3) Distorsion of cosmic diffuse radiation spectrum(COMPTEL) due to Gkk :

MD > 100 (5) TeV = 2 (3)

largeuncertainties but =2 disfavoured

Seattle experiment, Nov. 2000

R r r

1 ~ (r) V

1

R r e 1 r

1 ~ (r) V r/R-

R > 190 m MD > 1.9 TeV

r


1st example : direct G production in ADD models at LHC/SLHC

G

qq

g

topology is jet(s) + missing ET

2D M

1

MD = gravity scale = number of extra-dimensions

5 reach

Expected limits (Tevatron, HERA) in 2007:MD > 2-3 TeV for =3

SLHC : -- no major detector upgrade needed (high-pT calorimetric objects)-- similar reach for virtual G exchange-- G and /Z resonances observable up to 5-8 TeV


2nd example : virtual G exchange in ADD models at CLIC

expect deviations from SM expectation (e.g. cross-section, asymmetries)precise measurements at high-E machines arevery constraining

e+

e-

G

MD (

TeV

)

5 TeV

3 TeV

Indirect sensitivity up to ~ 80 TeV(depending on model) through precisionmeasurements


3nd example : Graviton resonance production in RS models at CLIC

e+e- + -

CLIC is resonance factory up to kinematic limit.Precise determination of mass, width, cross-section (from resonancescan `a la LEP1), branching ratios, spin …


6

6

Additional gauge bosons : Z ’

Mass can be measured to %(dominant error: calorimeter E-scale up to ~5 TeV, then statistics)

For Z-like Z’ with (Z’) / m(Z’) ~ 3%

direct discovery reach up to ~ 7 TeVLHC, SLHC

CLIC • direct discovery reach up to 3-5 TeV: mass and width can be measured to 10-3 – 10-4

from resonance scan• indirect reach from precise (~ %) EW measurements up to ~ 40 TeV


Contact interactions at LHC, SLHC

)ff( )eγe(g

jjiiij

2

2

RL,ji,ijCI

μ

L

14 TeV3000 fb-1

| * cos| -1

| * cos | 1

Quark sub-structure modifies di-jet angular distribution at Hadron Colliders

14 TeV 14 TeV 28 TeV 28 TeV300 fb-1 3000 fb-1 300 fb-1 3000 fb-1

40 60 60 85

95% C.L. lower limits on (TeV)

If b-tagging available can measure jet flavour


Contact interactions at CLIC)ff( )eγe(

g jjii

ij2

2

RL,ji,ijCI

μ

L

1000 fb-1

• From EW measurements• Sensitive to eeqq, ee complementary to Hadron colliders

Not allowed, couplings diverge ( > 1)

Not allowed (EW vacuum unstable, <0)

V ( ) = 2 | |2 + | | 4

mH 2 =2 (mZ) v 2

~ 115

CLIC s = 5 TeV can probe up to ~ 800 TeV


SUMMARY SUMMARY

• LHC upgrades : s = 14 TeV, L=1035 (SLHC) : extend LHC mass reach by 30% 7 TeV s = 28 TeV, L=1034 : extend LHC mass reach by 50% 8 TeV s = 28 TeV, L=1035 : extend LHC mass reach by 2 11 TeV

• SLHC : -- although some signatures (jets, ET

miss , , etc.) do not require major detector upgrades, new trackers (b-tag, e, ) allow larger discovery reach, more convincing results if at limit of sensitivity, precision measurements full benefit from L increase -- improves / consolidates LHC discovery potential and measurements

good physics return for “modest” cost ?

• s = 28 TeV : -- significant improvement of LHC discovery potential -- precision measurements for L = 1034

however: benefit/cost ratio too small ?

• CLIC : -- direct discovery potential and precise measurements up to 3-5 TeV can fill LHC “ holes ” in spectrum of New Physics -- indirect sensitivity up to scales 100-1000 TeV -- complementary to LHC, SLHC, VLHC

almost “ no-lose theorem” ?


Units are TeV (except TGC and WLWL reach) Ldt correspond to 1 year of running at nominal luminosity for 1 experiment

PROCESS LHC LC SLHC CLIC CLIC VLHC 14 TeV 0.8 TeV 14 TeV 3 TeV 5 TeV 200 TeV 100 fb-1 500 fb-1 1000 fb-1 1000 fb-1 1000 fb-1 100 fb-1

Squarks 2.5 0.4 3 1.5 2.5 15 Sleptons 0.34 0.4 1.5 2.5 Z’ 5 8† 6 20† 30† 30q* 6.5 0.8 7.5 3 5 70* 3.4 0.8 3 5Extra-dim (=2) 9 5-8.5† 12 20-33† 30-55† 65WLWL 3.0 7.5 70 90 30TGC (95%) 0.0014 0.0004 0.0006 0.00013 0.00008 0.0003 compositeness 35 100 50 300 400 130

† indirect reach (from precision measurements)

probes directly the 10-100 TeV scale

probes indirectly up to 1000 TeV

Comparison with TeV LC and VLHC


Factory and Muon Collider : a 3-step project

① factory : -- Superconducting Proton Linac (SPL) : high-intensity p source (1016 p/s, 2.2 GeV) using LEP RF cavities. Useful also for LHC, ISOLDE, CNGS (Conceptual Design Rep. ready) -- collection, cooling, acceleration to ~ 50 GeV, decay storage ring -- high-intensity and well-understood (flux, spectrum) e and beams for oscillation/mixing matrix studies

② Higgs factory : + - H -- s 115 1000 GeV -- better potential than e+e- LC of same s : smaller E-beam spread (~10-5), better E-beam calibration (to ~10-7 from e spectrum from polarised decays), (+- H) ~ 40000 (e+e- H) e.g. mW7 MeV, mtop MeV, H lineshape (mH 0.1 MeV, H 0.5 MeV at 115 GeV)

③ High-E Muon Collider : -- s 4 TeV (-radiation ~ E) -- better potential than e+e- LC of same s (see above), but no , options -- smaller E-beam spread but radiation detector background

excellent physicspotential at each step !

Fundamental questions to be solved for and :

cooling (fast ionisation cooling ?)cooling (fast ionisation cooling ?)and acceleration (re-circulating LINAC)and acceleration (re-circulating LINAC)

longerlongertime-scaletime-scalethan CLICthan CLIC


Examples of possible post-LHC scenarii and options (speculative …)

LHC finds SUSY (Higgs, squarks, gluino, and some gauginos and sleptons) TeV/multi-TeV LC to complete spectrum ? LHC finds SUSY (Higgs, gluino, stop, some gauginos) but no squarks of first generations VLHC and multi-TeV LC could be equally useful and complementary ?

LHC finds only one SM-like Higgs and nothing else multi-TeV LC to study Higgs properties and get clues of next E-scale up to 106 GeV ? give SUSY a last chance with a VLHC ?

LHC finds contact interactions < 60 TeV VLHC to probe directly scale ?

LHC finds Extra-dimensions MD < 15 TeV VLHC to probe directly scale MD ?

LHC finds nothing Higgs strongly interacting or invisible ? multi-TeV LC to look for Higgs and get hints of next E-scale ? LHC finds less conventional scenarii or totally unexpected physics ??

Note : here LC Lepton Collider


CONCLUSIONS

• Good reasons to believe that LHC, although powerful, will not be able to answer fully to important physics questions and that a new high energy/luminosity machine will be needed. Similar arguments apply to a 1 TeV LC.

• Because we ignore what happens at the TeV scale, and in the absence of theoretical preference for a specific energy scale beyond the TeV region, difficult to make a choice before LHC data will become available.

• However, to be in a position to make a proposal before/around 2010, i.e. for completion of the new machine by early 2020, vigorous accelerator and detector R&D is needed NOW.

• Several options considered at CERN: -- LHC luminosity upgrade (as a natural exploitation/evolution of existing machine). s = 28 GeV is likely not a large enough step for the cost of a new machine -- CLIC -- Muon Collider and neutrino storage ring

• Because of CERN financial problems, R&D effort now focused on CLIC: -- two-beam accelerator principle needs to be demonstrated as soon as possible -- CLIC has excellent and “almost granted” physics potential -- could be built on a reasonable time scale

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