physics opportunities with the fcc - dpnc.unige.chdpnc.unige.ch/seminaire/talks/janot.pdf ·...

Patrick Janot

PhysicsopportunitieswiththeFCC

28 March 2018 University of Geneva

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FCC-ee/hh LEP/LHC SPS

PS

See Seminar of Frank Zimmermann, Future Colliders for Particle Physics Jan 2018 See also three lectures on FCC at the CERN Academic Training, Oct. 2017

Patrick Janot

q  OutcomeoftheEuropeanStrategyforParticlePhysicsinMay2013◆  FromCERNCouncilofficialdocuments:

●  Notbasedonaphysicscase.Mostlytechnological/strategicalarguments.

GenesisoftheFCC


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CLIC

https://cds.cern.ch/record/1567295

https://cds.cern.ch/record/1567258/

FCC !

Patrick Janot

TheFCCConceptualDesignStudyq  StudykickedoffinGenevainFeb.2014q  Internationalcollaboration(124institutes)

◆  Studycircularcollidersfittinginanew~100kminfrastructure,intheGenevaarea

●  Baselinecircumference:97.75km

q  Ultimategoal:100TeVppcollider(FCC-hh)◆  RequiresR&Dfor16Tmagnets◆  Definestheinfrastructure

q  Possiblefirststeps◆  ppcollider(HE-LHC)intheLEP/LHCtunnel

●  WithFCC-hhtechnology(16T→26-27TeV)◆  e+e-collider(FCC-ee)attheintensityfrontier

●  Highluminosity,√s=90-400GeV

q  Possibleadd-on◆  e-poption(FCC-eh)

●  Withanew60GeVERLforelectrons


3

q  EuropeanStrategyupdate(2019)◆  Conceptualdesignreport(CDR)◆  Costreviewfortunnelandeachcollider◆  Schedulesandoperationmodels

Patrick Janot

GenesisoftheFCC-eeq  Seminalpapersstartedin2011

◆  OriginalideacamewiththefirsthintsfortheHiggsbosoninLHC(Dec.2011)

◆  Firstphysicsstudiesfollowedimmediatelyafter(Aug.2012)

◆  ExtendedtoalargertunnelinthewakeoftheHF2012workshop(Nov.2012)

q  ConcludedwiththeESPP’13famousstatement

q  UnambiguouslytailoredtoILCatthetime◆  TheFCC-eeturnsouttobeideally(andmuchbetter)suitedtothisphysicscase

●  ThesynergeticcombinationoftheFCC-eeandtheFCC-hhisuniqueandunbeatable●  Strategicallykillstwobirdsinonestone


4

A High Luminosity e+e− Collider in the LHC tunnel to study the Higgs Boson Alain Blondel (Geneva U.), Frank Zimmermann (CERN) https://arxiv.org/abs/1112.2518

Prospective Studies for LEP3 with the CMS Detector, Patrick Janot et al., https://arxiv.org/abs/1208.1662

Higgs Factory: Linear vs Circular (HF2012), Alain Blondel et al., https://indico.fnal.gov/event/5775/ First look at the physics case of TLEP, Patrick Janot et al., https://arxiv.org/abs/1308.6176

https://cds.cern.ch/record/1567258/

Patrick Janot

FCC-ee:Unprecedentedprecisionsq  Today:NotlessthanfiveprojectsforEWfactoriesintheworld

◆  TostudythepropertiesoftheHiggsboson●  Andotherparticles:theZ(91.2GeV)&W(80.4GeV)bosons,thetopquark(173.3GeV)

◆  Baselineluminositiesandcentre-of-massenergies:

q  TheFCC-eeuniquediscoverypotentialismultipliedbythepresenceofthefourheavyparticlesofthestandardmodelinitsenergyrange


5

q  Ultimateprecision@FCC-ee:◆  100000Z/second(!)

●  1Z/secondatLEP◆  10000W/hour

●  20000Win5yearsatLEP◆  1500Higgsbosons/day

●  10timesmorethanILC◆  1500topquarks/day

…ineachdetector◆  Inacleanexp’talenvironment:

●  nopileup;beambackgroundsundercontrol;E,pconstraints

Z WW HZ tt LEP×105!

CLIC

ILC

CEPC

FCCLEP3

-

Patrick Janot

FCC-ee:Luminositygoalsandoperationmodelq  TheFCC-eephysicsgoalsrequireatleast

◆  150ab-1atandaroundtheZpole(√s~91.2GeV)◆  10ab-1attheWWthreshold(√s~161GeV)◆  5ab-1attheHZcrosssectionmaximum(√s~240GeV)◆  0.2ab-1atthetopthreshold(√s~350GeV)and1.5ab-1above(√s~365GeV)

q  Operationmodel(with10%safetymargin)withtwoIPs◆  200scheduledphysicsdaysperyear(7months–13daysofMD/stops)◆  Hübnerfactor~0.75(lowerthanachievedwithKEKBtop-upinjection,~0.8)

◆  HalfthedesignluminosityinthefirstyearsofZandtopoperation(~LEP1)◆  MachineconfigurationbetweenWPschangedduringWintershutdowns(3months/year)

q  Totalrunningtime:13(+1)years(~LEP)


6

Workingpoint Z,years1-2 Z,later WW HZ ttthreshold 365GeV

Lumi/IP(1034cm-2s-1) 100 200 31 7.5 0.85 1.5

Lumi/year(2IP) 26ab-1 52ab-1 8.1ab-1 1.95ab-1 0.22ab-1 0.39ab-1

Physicsgoal 150 10 5 0.2 1.5

Runtime(year) 2 2 1 3 1 4

Longershutdowns:install196RFCMsLEPRecord:32inoneshutdown!

-

5×1012Z108WW106HZ106tt-

Patrick Janot

FCC-ee:Discoverypotentialinanutshellq  EXPLOREthe10-100TeVenergyscale

◆  WithprecisionmeasurementsofthepropertiesoftheZ,W,Higgs,andtopparticles●  20-50foldimprovedprecisiononALLelectroweakobservables(EWPO)

➨  mZ,ΓZ,mW,mtop,sin2θweff,Rb,αQED(mz),αs(mz),topEWcouplings…●  10foldmorepreciseandmodel-independentHiggscouplingsmeasurements

q  DISCOVERthattheStandardModeldoesnotfit◆  Thenextraweakly-coupledandHiggs-coupledparticlesexist◆  Understandtheunderlyingphysicsthrougheffectsvialoops

q  DISCOVERaviolationofflavourconservation/universality◆  Examples:Z→τµin5×1012Zdecays;ort→cZ,cHat√s=240or350GeV◆  Alsoalotofflavourphysicsin1012bbevents,e.g.,withB0→K*0τ+τ- orBS→τ+τ-

q  DISCOVERdarkmatterasinvisibledecaysofHiggsorZ

q  DISCOVERveryweaklycoupledparticlesinthe5-100GeVmassrange◆  Suchasright-handedneutrinos,darkphotons,…

●  Mayhelpunderstanddarkmatter,universebaryonasymmetry,neutrinomasses


7

-

MayhelpshapeupFCC-hhdetectors

Today,wedonotknowhownaturewillsurpriseus:otherthingsmaycomeupwithFCC-ee

Patrick Janot

FCC-ee:Energyupgradeq  RequestedbytheEuropeanStrategystatement(2013)

◆  Inlineare+e-colliders,anenergyupgradeismostlyrelevantfor●  Theproductionandstudyof(a)putativenewparticle(s)athighmass

➨  TheILCbaselinedesignnolongerplansanenergyupgrade➨  ThedomaincoveredbyCLIC(0.4–3TeV)isbeingexploredbytheLHC

CLICbecomesaninterestingoptiontoconsiderifanewparticleproducedine+e-collisionswerediscovered/hintedatinthisrangebytheLHC

➨  Amuchbiggerenergystepisneededtogobeyond→hadroncollidersWith√s=100TeV,theFCC-hhhasaccesstoabroaderrangeTheSppCislessambitiouswithR&Dfor12Tdipoles

●  ThemeasurementofthetopYukawacoupling(ttH)andHiggsselfcoupling(HHH)➨  IncombinationwithFCC-ee,theFCC-hhdoesbetterthanlinearcolliders

q  TheFCC-hhisthemostambitiousscientifically◆  Withnumeroussynergiesandcomplementarities

●  Tunnel,infrastructure,cryogenics,time,long-termCERNfuture,andphysics◆  AnditpavesthewaytotheFCC-µµ,aleptoncolliderwithpotentiallymuchhigher√s


8

Patrick Janot

FCC-hh:Luminositygoalsandeventratesq  Luminosityandpileup

◆  HL-LHC:3ab-1at14TeVin15years,upto200PU◆  HE-LHC:10ab-1at27TeVin15years,upto850PU◆  FCC-hh:20ab-1at100TeVin25years,upto1000PU

●  Baseline:0.25ab-1thefirstyear,increasingfor~10yearstowards…●  Ultimate:1.5ab-1/yearfor15years

q  Eventrates(examples)◆  2×1010Higgsbosons(200×HL-LHC)

●  2×107pairsofHiggs(400×HL-LHC)●  108ttHevents(600×HL-LHC)

◆  1012toppairs(300×HL-LHC)◆  105pairsofgluinosifmgluino~8TeV(noneatHL-LHC)◆  5×1013Wbosons,1013Zbosons(70×HL-LHC)◆  …


9

Patrick Janot

FCC-hh:Discoverypotentialq  Twomainfeatures

◆  MassreachofdirectparticleobservationenhancedbyafactorE/14TeV~7@100TeV●  Newgaugebosonsupto40TeV●  Strongly-interactingparticlesupto15-20TeV●  NaturalSUSYupto5-20TeV●  Darkmatterupto1.5–5TeV

➨  PossibilitytofindorruleoutthermalWIMPDMcandidates●  Increasedsensitivitytohigh-energyphenomena(e.g.WWscattering,Drell-Yan)

◆  Hugeproductionrates●  PrecisionstudyofHiggsandtopquarkproperties

➨  ExplorationofEWSBphenomenawithunmatchablesensitivityYes/No:DidbaryogenesistakeplaceduringEWphasetransition?

➨  RareorBSMdecays●  Sensitivitytoheavynewphysicsthroughindirect(precision)probes

➨  E.g.,withratiosofcrosssections➨  E.g.,withhigh-pTfinalstatesforchannelssystematics-limitedattheLHC

ShiftbetweenstatisticsandsystematicsFurtherimprovedbysynergieswithFCC-ee


10

Physics at the FCC-hh: https://cds.cern.ch/record/2270978

Patrick Janot

FCC-hh:Detectorsq  Aformidablechallenge,wellbeyondHL-LHC

◆  Muchlargerlongitudinaleventboost●  Enhancedcoverageatlargerapidity(withtrackingandcalorimetry)●  Forwardsolenoidsordipoles●  Length~46m

◆  Zs,Ws,Higgses,topswillbehighlyboosted(esp.inhighpTfinalstates)●  Highgranularitytrackingandcalorimetry●  4T,10mboremainsolenoidsurroundingthecalorimeters

◆  Upto1000PUeventsoverabunchlengthof5cm●  Highresolutionvertexing●  Ultrafastdetector/electronics

◆  Energeticjets●  2m-thickHCAL

◆  HighpTmuons●  20%resolution@10TeV

◆  Radiationhardness◆  …


11

See Werner Riegler’s Academic Training here

Patrick Janot

FCC-ee:Detectorsq  Twobaselinedesignsaimedforhigh-precisionmeasurements(~10-5)

◆  CLD:CLICdesignadaptedforFCC-eeIDEA:FCC-eespecific,R&Dahead

◆  Silicontracker,thickness~30%X0Driftchamber(50Kwires,L=4m,0.4%X0)◆  Highgranularity(3D+timing)calorimetry2T,4mboresolenoidaroundtracker◆  2T,8mboresolenoidaroundcalorimetersDualreadoutlead/fibrecalorimeter◆  +maybealargesurroundingtrackertoenhancelong-livedparticlesearches?


12

UltraLightInnovativeCosteffective

ProvenconceptKnownperformancefromfullsimulation

Patrick Janot 28 March 2018

University of Geneva 13

ElectroweakPrecisionMeasurements

Patrick Janot

EWPOs@FCC-ee

28 March 2018

q  Boilsdowntomeasuringcrosssectionsandasymmetries

◆  Dominantexp’taluncertainties:beamenergyknowledge,luminositymeasurement


0200400

(GeV) s50 60 70 80 90 100 110 120 130 140 150

_)/_(

m

-510

-410

at FCC-eeµµ

FB accuracy from AQED_

(GeV) s50 60 70 80 90 100 110 120 130 140 150

µµ FBA

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

AFB(µµ)

√s(GeV) √s(GeV)

Δα/α

Currentuncertainty

With 2×40 ab-1

√s(GeV)

mZ,ΓZ

mW, ΓW

mt, Γt, λt

HZ •  Measuresin2θWwithAFBat√s=mZ

•  MeasureαQED(mZ)withAFBat√s=87.9and94.3GeV

•  MeasuremZ, ΓZ fromthethree-pointZresonancescan

AFBµµ =

NFµ+ − NB

µ+

NFµ+ + NB

µ+≈ f (sin2ϑW

eff )+αQED (s)s−mZ

2

2sg(sin2ϑW

eff )

e+e-→µ+µ-

e+e-→qq,WW,tt- -

Patrick Janot

FCC-ee:Beamenergycalibrationq  Auniquefeaturecirculare+e- colliders

◆  Achievetransversepolarizationofafew10’sofmonitoringnon-collidingbunches●  Outof16000or1300bunchesattheZandWenergies●  Requireswigglerstohavefastpolarizationatthebeginningofphysicsrun●  Toomuchdepolarizingeffects(SR,energyspread)athigherenergies

◆  “Continous”beamenergycalibrationwithresonantdepolarization●  Onemonitoringbunchatatime●  Demonstrated(andused)atLEP,outsidephysicsruns(extrapolationerror2MeV)

◆  Targetprecisionon√sis±100keVattheZpole(mZ)andattheWWthreshold(mW)●  Crucialforsensitivitytonewphysicsofallelectroweakmeasurements●  AboveWWthreshold:UseWW,ZZandZγeventstodetermine√sfrommWandmZ

◆  Systematicstudiesongoingwithpromisingperspective

q  Noteaboutlongitudinalpolarization(naturalatlinearcollider)◆  Muchlowerprioritythantransversepolarization

●  Bringsnoinformationthatcannotbeobtainedotherwise(largeFCC-eestatistics)➨  Fromunpolarizedasymmetriesorfromfinalstatepolarization(tau,top)

●  Causestoomuchlossofluminositytoprovidegaininprecision


15

Patrick Janot

FCC-ee:Luminositymeasurementq  Notmuchroomfortheluminositycounter(withlowangleBhabhae+e-→e+e-)

◆  Emittanceblow-upfromdetectormagneticfield(beamcrossingatangle)●  RequiresacompensatingsolenoidevenclosertotheIP

➨  Whichinturnlimitsthedetectormagneticfieldto2T●  Andamagneticshieldingaroundthefinalfocusquads

◆  LumiCalFrontfaceat1.2mfromtheIP(insidethetracker–was~2.5matLEP)

●  Strongmagneticforces,quenches:dangerouslongitudinalmovements➨  LumiCalsupportedbythecalorimeter,fixedtothecentralbeampipe

◆  Currentchallenge:Outgoingelectronsdeflectedbychargedensityoftheotherbunch●  Effect10timeslargerthantherequiredluminosityaccuracy(10-4)


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2m

Beam pipes

Luminosity counter

Compensating solenoid

Shielding solenoid

Final focus quads

3 m

2 m 1 m

Patrick Janot

FCC-ee:Summaryofprecisionsachievable


17

Observable Measurement Currentprecision TLEPstat. Possiblesyst. Challenge

mtop(MeV) Thresholdscan 173340±760±500 20 <40 QCDcorr.

Γtop(MeV) Thresholdscan ? 40 <40 QCDcorr.

λtop Thresholdscan µ=1.2±0.3 0.08 <0.05 QCDcorr.

ttZcouplings √s=365GeV ~30% ~2% <2% QCDcorr

Observable Measurement Currentprecision TLEPstat. Possiblesyst. Challenge

mw(MeV) Thresholdscan 80385±15 0.6 <0.6 EWCorr.

ΓW(MeV) Thresholdscan 2085±42 1.5 <1.5 EWCorr.

Nν e+e-→γZ,Z→νν,ll 2.92±0.05 0.001 <0.001 ?

αs(mW) Bhad=(Γhad/Γtot)W Bhad=67.41±0.27 0.00018 <0.0001 CKMMatrix

Observable Measurement Currentprecision FCC-eestat. Possiblesyst. Challenge

mZ(MeV) Lineshape 91187.5±2.1 0.005 <0.1 QEDcorr.

ΓZ(MeV) Lineshape 2495.2±2.3 0.008 <0.1 QED/EW

Rl Peak 20.767±0.025 0.001 <0.001 Statistics

Rb Peak 0.21629±0.00066 0.000003 <0.00006 g→bb

Nν Peak 2.984±0.008 0.00004 <0.004 Lumimeast

sin2θWeff AFBµµ (peak) 0.23148±0.00016 0.000003 <0.000005 Beamenergy

1/αQED(mZ) AFBµµ (off-peak) 128.952±0.014 0.004 <0.004 QED/EW

αs(mZ) Rl 0.1196±0.0030 0.00001 <0.0002 NewPhysics

Patrick Janot

q  Electroweakobservablesaresensitivetoheavyparticlesin“loops”◆  Forexample,inthestandardmodel:Γ(Z→µ+µ-)ormW

◆  WithprecisemeasurementsoftheZmass,Zwidth,andWeinbergangle[+αQED(mZ)]●  LEPconfirmedtheexistenceofthetopquarkandwasabletopredictmtopandmW

◆  Withtheobservationofthetop(Tevatron)attherightmass●  LEPconfirmedtheexistenceoftheHiggsbosonandwasablepredictmH

◆  WiththeobservationoftheHiggs(LHC)attherightmass●  LEPwasabletoimprovethemWprediction(andmeasuredmWaswell)

mW2 =

παQED mZ2( )

2GF sin2θW

×1

1−Δr

Precision⟺Discovery


18

Γll =GF

2mZ3

24π1+ 1

4− sin2θW

eff⎡

⎣⎢⎤

⎦⎥

2⎛

⎝⎜⎜

⎞

⎠⎟⎟× 1+Δρ( )

Δρ =απmt2

mZ2 −

α4πLogmH

2

mZ2 +!≈1% Δr = − cos

2ϑW

sin2ϑW

Δρ +α3π

12−13sin2ϑW

1− tan2ϑW

⎡

⎣⎢

⎤

⎦⎥Log

mH2

mZ2 +!≈1%

µ+

µ- µ-

µ+

sin2ϑWeff = 1− mW

2

mZ2

⎛

⎝⎜

⎞

⎠⎟× (1+Δκ )

Patrick Janot

[GeV]tm140 150 160 170 180 190

[GeV

]W

M

80.25

80.3

80.35

80.4

80.45

80.568% and 95% CL contours

measurementst and mWfit w/o M measurementsH and Mt, mWfit w/o M

measurementst and mWdirect M

σ 1± world comb. WM 0.015 GeV± = 80.385 WM

σ 1± world comb. tm = 173.34 GeVtm

= 0.76 GeVσ GeV theo 0.50⊕ = 0.76 σ

= 125.14 GeV

HM = 50 GeV

HM = 300 GeV

HM = 600 GeV

HM G fitter SM

Jul ’14

Precision⟺Discovery,cont’dq  Withmtop,mHandmWknown,thestandardmodelhasnowheretogo

q  TheFCC-eewillsignificantlyimproveprecisiononallfronts◆  Moreprecisemeasurementsbecomesensitivetoother(heavier)particlesintheloops

●  Ifoneingredientismissing,thesensitivitytonewphysicsdrops/vanishes➨  Fullprogramme(fromtheZpoletoabovethetopthreshold)welljustified

●  Theoreticalcalculationsneedtobebroughttohigherorders(moreloops)


19

LEP,Tevatron,LHC

Teva

tron

,LHC

LEP(EWprecisionmeasurements)

LEP+mH(LHC)

https://arxiv.org/pdf/1407.3792.pdf

FitoftheSMandnothingelse

Patrick Janot

Precision⟺Discovery,cont’dq  CombiningallFCC-eeEWmeasurements

◆  InthecontextoftheSM…andbeyond

◆  Newphysics:blueandredellipsesmaynotoverlap●  Orevenbetter,datamaynotfittotheSM


20

Requires10-foldimprovedtheorycalculations

No theory uncertainties

6/17/2016 E.Perez15

Higgscouplings

Precision and indirect searches for new physicsTop couplings

Extra-dim models: Probe NP scalesof O ( 20 TeV )

4D-CHM,f < 2 TeV

Ex. NP models,probed by HL-LHC

EW precision

Power of loops :In terms of weakly-coupled new physics: ΛNP > 30 – 100 TeV

J. Ellis & T. You, JHEP03 (2016) 089

ILC Physics case, arXiv:1506.05992

Theo. uncertainties need to be improved inthe next 20 years, to match the exp. uncertainties

P. Janot, arXiv:1510.09056D. Barducci et al, JHEP 1508 (2015) 127

AfterFCC-ee:Λ/√c > 50-100TeV?

FCC-ee projections

J. De Blas, Jan. 2017

w/o theory uncertainties

with current theory uncertainties

Today: Λ/√c > 5-10 TeV

PointstothephysicstobelookedforatFCC-hhΛ

(TeV

)

Patrick Janot

FCC-ee:Theorycalculationsq  Today

q  WithFCC-ee

q  TheoryR&D


21

ConclusionfromPrecisionCalculationsMini-WorkshopinJanuary2018:Thenecessarytheoreticalworkisdoablein5-10yearsperspective,duetosteadyprogress in methods and tools, including the recent completion of NNLO SMcorrectionstoEWPOS.Thisstatement isconditionaltoastrongsupportbythefundingagenciesand theoverall community.Appropriatefinancial supportandtrainingprogramsfortheseprecisioncalculationsaremandatory.

±0.0006 GeV

Patrick Janot

FCC-hh:Probesdim6op’swithhighmassDYq  Overallcredo:Tradeextremeprecisionfordynamicalrange@100TeV

◆  Inthesamepursuitofhigh-scalesensitivity●  EffectofDim6operatorinaprocesswithmomentumtransferQonobservableO


22

cY cW cZ

ΛY/√cY ΛW/√cW ΛZ/√cZV

AtQ~100GeV,precisionprobeslargeΛe.g.δO=10-4⇒Λ~10TeVLargerQprobelargeΛevenifprecisionislowe.g.δO=15%atQ=4TeV⇒Λ~10TeV

GlobalfitwithFCC-eebeingperformed



ElectroweakSymmetryBreakingTheHiggsbosonasaBSMprobe

Patrick Janot

FCC-ee:Higgsbosonproductionq  Largestrateat√s~240GeV:106e+e-→HZeventswith5ab-1

◆  Complementedwithanother200keventsat√s=350–365GeV●  Ofwhich30%intheWWfusionchannel(usefulfortheΓHprecision)


24

1.2 Theoretical structure of the Standard Model Higgs boson

Table 1.1. The Standard Model values of branching ratios of fermionic decays of the Higgs boson for each value ofthe Higgs boson mass mh.

mh (GeV) b¯b ·+·≠ µ+µ≠ cc ss125.0 57.7 % 6.32 % 0.0219 % 2.91 % 0.0246 %125.3 57.2 % 6.27 % 0.0218 % 2.89 % 0.0244 %125.6 56.7 % 6.22 % 0.0216 % 2.86 % 0.0242 %125.9 56.3 % 6.17 % 0.0214 % 2.84 % 0.0240 %126.2 55.8 % 6.12 % 0.0212 % 2.81 % 0.0238 %126.5 55.3 % 6.07 % 0.0211 % 2.79 % 0.0236 %

Table 1.2. The Standard Model values of branching ratios of bosonic decays of the Higgs boson for each value ofthe Higgs boson mass mh. The predicted value of the total decay width of the Higgs boson is also listed for eachvalue of mh.

mh (GeV) gg ““ Z“ W +W ≠ ZZ �H (MeV)125.0 8.57 % 0.228 % 0.154 % 21.5 % 2.64 % 4.07125.3 8.54 % 0.228 % 0.156 % 21.9 % 2.72 % 4.11125.6 8.52 % 0.228 % 0.158 % 22.4 % 2.79 % 4.15125.9 8.49 % 0.228 % 0.162 % 22.9 % 2.87 % 4.20126.2 8.46 % 0.228 % 0.164 % 23.5 % 2.94 % 4.24126.5 8.42 % 0.228 % 0.167 % 24.0 % 3.02 % 4.29

are listed for mh = 125.0, 125.3, 125.6, 125.9, 126.2 and 126.5 GeV [47]. In Table 1.2 the predictedvalues of the total decay width of the Higgs boson are also listed. It is quite interesting that witha Higgs mass of 126 GeV, a large number of decay modes have similar sizes and are accessible toexperiments. Indeed, the universal relation between the mass and the coupling to the Higgs boson foreach particle shown in Fig. 1.1 can be well tested by measuring these branching ratios as well as thetotal decay width accurately at the ILC. For example, the top Yukawa coupling and the triple Higgsboson coupling are determined respectively by measuring the production cross sections of top pairassociated Higgs boson production and double Higgs boson production mechanisms.

1.2.4 Higgs production at the ILC

At the ILC, the SM Higgs boson h is produced mainly via production mechanisms such as theHiggsstrahlung process e+e≠ æ Zú æ Zh (Fig. 1.3 Left) and the the weak boson fusion processese+e≠ æ W +úW ≠ú‹‹ æ h‹‹ (Fig. 1.3 (Middle)) and e+e≠ æ ZúZúe+e≠ æ he+e≠. TheHiggsstrahlung process is an s-channel process so that it is maximal just above the threshold of theprocess, whereas vector boson fusion is a t-channel process which yields a cross section that growslogarithmically with the center-of-mass energy. The Higgs boson is also produced in association witha fermion pair. The most important process of this type is Higgs production in association with a topquark pair, whose typical diagram is shown in Fig. 1.3 (Right). The corresponding production crosssections at the ILC are shown in Figs. 1.4 (Left) and (Right) as a function of the collision energy byassuming the initial electron (positron) beam polarization to be ≠0.8 (+0.2).

The ILC operation will start with the e+e≠ collision energy of 250 GeV (just above threshold forhZ production), where the Higgsstrahlung process is dominant and the contributions of the fusionprocesses are small, as shown in Fig. 1.4 (Left) . As the center-o�-mass energy,

Ôs increases, the

Z

ZHe+

e< i

i<

W

WH

e+

e<

e+

e−

H

t

t-

γ/Z

Figure 1.3. Two important Higgs boson production processes at the ILC. The Higgsstrahlung process (Left), theW-boson fusion process (Middle) and the top-quark association (Right).

19

1.2 Theoretical structure of the Standard Model Higgs boson

Table 1.1. The Standard Model values of branching ratios of fermionic decays of the Higgs boson for each value ofthe Higgs boson mass mh.

mh (GeV) b¯b ·+·≠ µ+µ≠ cc ss125.0 57.7 % 6.32 % 0.0219 % 2.91 % 0.0246 %125.3 57.2 % 6.27 % 0.0218 % 2.89 % 0.0244 %125.6 56.7 % 6.22 % 0.0216 % 2.86 % 0.0242 %125.9 56.3 % 6.17 % 0.0214 % 2.84 % 0.0240 %126.2 55.8 % 6.12 % 0.0212 % 2.81 % 0.0238 %126.5 55.3 % 6.07 % 0.0211 % 2.79 % 0.0236 %

Table 1.2. The Standard Model values of branching ratios of bosonic decays of the Higgs boson for each value ofthe Higgs boson mass mh. The predicted value of the total decay width of the Higgs boson is also listed for eachvalue of mh.

mh (GeV) gg ““ Z“ W +W ≠ ZZ �H (MeV)125.0 8.57 % 0.228 % 0.154 % 21.5 % 2.64 % 4.07125.3 8.54 % 0.228 % 0.156 % 21.9 % 2.72 % 4.11125.6 8.52 % 0.228 % 0.158 % 22.4 % 2.79 % 4.15125.9 8.49 % 0.228 % 0.162 % 22.9 % 2.87 % 4.20126.2 8.46 % 0.228 % 0.164 % 23.5 % 2.94 % 4.24126.5 8.42 % 0.228 % 0.167 % 24.0 % 3.02 % 4.29

are listed for mh = 125.0, 125.3, 125.6, 125.9, 126.2 and 126.5 GeV [47]. In Table 1.2 the predictedvalues of the total decay width of the Higgs boson are also listed. It is quite interesting that witha Higgs mass of 126 GeV, a large number of decay modes have similar sizes and are accessible toexperiments. Indeed, the universal relation between the mass and the coupling to the Higgs boson foreach particle shown in Fig. 1.1 can be well tested by measuring these branching ratios as well as thetotal decay width accurately at the ILC. For example, the top Yukawa coupling and the triple Higgsboson coupling are determined respectively by measuring the production cross sections of top pairassociated Higgs boson production and double Higgs boson production mechanisms.

1.2.4 Higgs production at the ILC

At the ILC, the SM Higgs boson h is produced mainly via production mechanisms such as theHiggsstrahlung process e+e≠ æ Zú æ Zh (Fig. 1.3 Left) and the the weak boson fusion processese+e≠ æ W +úW ≠ú‹‹ æ h‹‹ (Fig. 1.3 (Middle)) and e+e≠ æ ZúZúe+e≠ æ he+e≠. TheHiggsstrahlung process is an s-channel process so that it is maximal just above the threshold of theprocess, whereas vector boson fusion is a t-channel process which yields a cross section that growslogarithmically with the center-of-mass energy. The Higgs boson is also produced in association witha fermion pair. The most important process of this type is Higgs production in association with a topquark pair, whose typical diagram is shown in Fig. 1.3 (Right). The corresponding production crosssections at the ILC are shown in Figs. 1.4 (Left) and (Right) as a function of the collision energy byassuming the initial electron (positron) beam polarization to be ≠0.8 (+0.2).

The ILC operation will start with the e+e≠ collision energy of 250 GeV (just above threshold forhZ production), where the Higgsstrahlung process is dominant and the contributions of the fusionprocesses are small, as shown in Fig. 1.4 (Left) . As the center-o�-mass energy,

Ôs increases, the

Z

ZHe+

e< i

i<

W

WH

e+

e<

e+

e−

H

t

t-

γ/Z

Figure 1.3. Two important Higgs boson production processes at the ILC. The Higgsstrahlung process (Left), theW-boson fusion process (Middle) and the top-quark association (Right).

19

Patrick Janot

FCC-ee@240:Model-independentcouplingsq  HtaggedbyaZandmRecoil(indep.ofHdecay)

◆  Measureσ(e+e-→HZ);deducegZcoupling●  InferΓ(H→ZZ*)proportionalto(gZ)2

◆  Measureσ(e+e-→HZ,withH→ZZ*)

●  DeducethetotalHiggsbosonwidthΓH➨  SignificantlyimprovedwithWW→H→WW,bb@365GeV

◆  Measureσ(e+e-→HZ,withH→bb,cc,gg,WW,ττ,γγ,µµ,Zγ,…)●  Deducegb,gc,gg,gW,gτ,gγ,gµ,gZγ,...

◆  SelecteventswithH→“nothing”●  DeduceBR(H→invisible)

q  With106HZevents,precisionsrangefrom0.2%to5%◆  SensitivitytoBRinv~0.5%;PrecisiononΓH~1%◆  Note:100KH→ggeventsforgluonfragmentationstudies


25 e+e-→ HZ

mH2 = s+mZ

2 − 2 s(E+ +E− )

µ+

µ-

σ (e+e− →HZ→ ZZZ ) =σ (e+e− →HZ )× Γ(H→ ZZ )ΓH

gZ.gW gµ , gZγ

Patrick Janot

FCC-ee:SensitivitytonewPhysicsq  Higgs-couplednewphysicsinSMEFT

◆  Probesdim6operatorsfor Λ/√cupto5–30TeV

q  Specificmodels:patternofdeviations◆  E.g,CompositeHiggsModeltosolvehierarchyproblem

●  DeviationsinHiggscouplings●  DeviationsinEWtopcouplings●  DeviationsinEWleptoncouplings

◆  Correlationsbetweenobservations●  Allowuniquecharacterizationofthemodel

◆  Forexample,gaugesectorparametersinbenchmarkA●  f=1.6TeV,g*=1.78,mZ’~3TeV,ΓZ’~600GeV●  WiththeFCC-eeprecision

➨  Z’masspredictedwth2%precision➨  Scalef,couplingg*predictedwith8%precision


26

gbvsgZ

tRtRZvstLtLZ

σµµ(√s)

Patrick Janot

FCC-ee:ttHandHHHcouplings?q  Model-dependentmeasurementsarepossible

◆  ToppaircrosssectionatthresholdHiggscrosssectionat240,350,and365GeV

◆  TopYukawacouplingprecision<10%

◆  Higgsselfcouplingprecision~30%●  Reducedto~20%withgHZZfromSM


27

FCC-eeαsprecisionmeasurementhelps!(GluonandHiggsexchangescompete)

https://arxiv.org/pdf/1711.03978.pdf

SimilarprecisionsareobtainedwithdoubleHiggsproductionatCLIC(√s=1.4and3TeV)orwiththe

(nolongerconsidered)0.5+1TeVupgradeoftheILC

365

Patrick Janot

t

tH

t

tZ

vs

- Identical production dynamics:

o correlated QCD corrections, correlated scale dependenceo correlated αS systematics

- mZ~mH ⇒ almost identical kinematic boundaries:

o correlated PDF systematicso correlated mtop systematics

To the extent that the qqbar → tt Z/H contributions are subdominant:

+

For a given ytop, we expect σ(ttH)/σ(ttZ) to be predicted with great precision

t

t

H

t

t

Zt

t

Z

+

+

Example, ytop from pp→tt H/pp→tt ZDominant

FCC-hh:ttHandHHHcouplingsq  ttHproductionevidencewith4.2σinATLAS

◆  MeasurementofσttH/σSMsystematics-limited

q  AtFCC-hh,tradestatisticsforsystematics◆  MeasureσttH/σttZatlargepT(H,Z)

●  Verysimilarproductionmechanism●  Mosttheoryuncertaintiescancel

◆  UsettZcouplingmeasurements@FCC-eetopredictσttZ

q  DoubleHiggsproductiondifficultatHL-LHC◆  Sensitivitytoselfcouplingreducedbydestructiveinterference

q  AtFCC-hh,gotolargepT(H)again◆  HH→bbγγchannel:pT(bb),pT(γγ)>100GeV◆  StatisticaltargetonλH:3.4%with20ab-1

●  Systematicstudiesongoing,e.g.,➨  Signal&backgroundSMrates➨  Luminositymeasurement➨  Effectofpileup

28 March 2018


bbγγ ttH

HHmbb vs mγγΔλH/λH~5%

BR(H→ bb,ZZ) from FCC-ee

Δλt/λt~1%

Patrick Janot

FCC-hh:OtherHiggscouplingsq  Example:gg→H→γγ

◆  AtLHC,S/Boftheorderofafew%

◆  AtFCC-hh,S/B~1forpT(H)>300GeV●  Statisticaluncertaintystill<0.5%●  pTspectrumasBSMprobe

q  Precise“ratios-of-BRs”measurements◆  Manytheorysystematicuncertaintiescancel◆  AbsoluteBRfromfeedbackofprecisegHZZFCC-eemeasurement◆  OneshouldnotunderestimatethestandalonevalueoftheseratiosasBSMprobes

●  BSMeffectstypicallyinfluenceBRsindifferentways➨  BR(H→γγ)/BR(H→ZZ*):loop-levelvstree-level➨  BR(H→µµ)/BR(H→ZZ*):2ndgenerationYukawavsgaugecoupling➨  BR(H→γγ)/BR(H→Zγ):differentEWchargesintheloops


29

Patrick Janot

FCC-hh:Higgsmeasurementsummaryq  Typicaltargetprecisions~%

◆  ConstraintsonBSMmodelsunderstudy


30

95%CLsensitivity~4timesbetterthanSMBR(H→ZZ*→νννν)



DiscoverypotentialviadirectobservationAfewexamples

Patrick Janot

FCC-hh:Discoverypotentialathighestmassesq  SUSY:AdditionalHiggsbosons(A,H,H±)upto~10TeV

●  Beyondanycurrentleptoncolliderdesign


32

arXiv:1605.08744 arXiv:1504.07617

Patrick Janot

FCC-hh:Discoverypotentialathighestmassesq  Newgaugebosons

◆  Z’→µµcancoveralltheparameterspacewhere“LHCbanomalies”fitwithZ’interpretation


33

Patrick Janot

FCC-hh:Discoverypotentialathighestmassesq  2ndgenleptoquarks(aspossibleexplanationforLHCb“anomalies”)

◆  PairproductionSingleproduction

●  Cancoverlargepartofthe“LHCbanomalies”parameterspacewhichfitwiththeLQinterpretation


34

Ben Allanach, 2nd FCC Physics workshop

Patrick Janot

q  SUSYandWIMPDarkMatter:Farbeyondthenaturalnessparadigm◆  Simplifiedmodels:samecaveatsasatLHCapply–directdiscoverymightbehidden

●  NLSP/LSPmasssplitting;100%BR;HeavyDMmediators;…

◆  FromDMrelicabundance:

●  FCC-hhcandind(orruleout)lot’sofweaklyinteractingmassiveDMcandidates.

FCC-hh:Discoverypotentialathighestmasses


35

Patrick Janot

NOT FOR DISTRIBUTION JINST_044P_0315 v1

HNL mass (GeV)1 10

2|U

|

-1110

-1010

-910

-810

-710

-610Inverted hierarchy

BBN

Seesaw

BAUPS191CHARM

NuTeV

SHiP 0 Z12FCC-ee 101 mm < r < 1 m

0 Z13FCC-ee 10m < r < 5 mµ100

Figure 1. Physics reach in the nMSM for SHiP andtwo realistic FCC-ee configurations (see text). Pre-vious searches are shown (dashed lines), as well asthe cosmological boundaries of the model (greyed-out areas) [3, 9].

' mass (GeV)γ

-310×3 -210 -210×2 -110 -110×2 1 2 3 4 5

ε' c

oupl

ing

to S

M

γ

-1210

-1110

-1010

-910

-810

-710

-610

-510

-410

-310

-210

'γ p+→p 'Xγ →mesons

previous experimental limits

BBN excluded areas

D/H

He4

Li/H7

Figure 2. SHiP sensitivity to dark photons producedin proton bremmstrahlung and secondary mesons de-cays. Previous searches explored the greyed-out area.Low-coupling regions are excluded by Big Bang Nu-cleosynthesis.

A method similar to the one outlined in Section 2 was used to compute the expected number ofevents. HNL production is assumed to happen in Z ! nn decays with one neutrino kinematicallymixing to an HNL. If the accelerator is operated at the Z resonance, Z bosons decay in place andthe HNL lifetime is boosted by a factor

g =mZ

2mN+

mN

2mZ. (3.1)

All `+`�n final states are considered detectable with a CMS-like detector with spherical symmetry.Backgrounds from W ⇤W ⇤, Z⇤Z⇤ and Z⇤g⇤ processes can be suppressed by requiring the presenceof a displaced secondary vertex.

Figure 1 shows SHiP’s and FCC-ee’s sensitivities in the parameter space of the nMSM, fortwo realistic FCC-ee configurations. The minimum and maximum displacements of the secondaryvertex in FCC-ee, referred to as r in Figure 1, depends on the characteristics of the tracking system.Inner trackers with resolutions of the order of 100 µm and 1 mm, and outer trackers with diametersof 1 m and of 5 m have been considered. Figure 2 shows SHiP’s sensitivity to dark photons,compared to previous searches.

This work shows that the SHiP experiment can improve by several orders of magnitude thecurrent limits on Heavy Neutral Leptons, scanning a large part of the parameter space below theB meson mass. Similarly, SHiP can greatly improve present constraints on dark photons. Right-handed neutrinos with larger mass can be searched for at a future Z factory. The synergy betweenSHiP and a future Z factory would allow the exploration of most of the nMSM parameter space forsterile neutrinos.

Acknowledgments

This work would not have been possible without the precious theory support by M. Shaposhnikov.We thank A. Blondel for useful discussions about the FCC-ee project. We are indebted to all our

– 3 –

FCC-ee:Highmassorsmallcouplings?q  (Oneofthe)mostnaturalextensionofthestandardmodel:theνMSM

◆  Completeparticlespectrumwiththemissingthreeright-handedneutrinos

●  Couldexplaineverything:Darkmatter(N1),Baryonasymmetry,Neutrinomasses◆  SearchedforatFCC-eeinveryrareZ→νN2,3decays

●  FollowedbyN2,3→W*𝓵orZ*ν


TheνMSMTheSM

Veryweakcoupling:longlifetime,detachedvertex36

Patrick Janot

FCC-ee:Highmassorsmallcouplings?q  MixingwithνRreduceνLcouplings

◆  AffectmanyprecisionobservablesatFCC-ee●  Leptonicτbranchingratios(1.5×1011ττatFCC-ee)●  Rarelepton-flavour-conservation-violatingdecays

➨  Irrespectiveofthemassoftheright-handedneutrino(>>100TeV!)


37

Detachedvertices

Precisiontestsq  DiscoverywouldshapeupFCC-hhdetectors

◆  Fordisplacedvertexsearches,◆  andlepton-flavour-violatingsignatures

●  TowardstestsofthePMNSmatrix

q  DetailedFCC-hhstudyrequired◆  Tounderstandfeasibility



Flavourphysics

Patrick Janot

FCC-ee:Flavourphysicsq  Currenttensions(several2-3σ deviations)ofLHCbdatawithSMpredictions

◆  Inparticular,leptonflavouruniversalityischallengedinb→s𝓵+𝓵-transitions●  Forexample,theratesofB0(B+)→K*0(K+)𝓵+𝓵-aredifferentfor𝓵=eand𝓵=µ●  Differencesarealsoobservedintheleptonangulardistributions

◆  Thiseffect,ifreal,couldbeenhancedfor𝓵=τ,inB→K(*)τ+τ- ●  Extremelychallenginginhadroncolliders●  With1012Z→bb,FCC-eeisbeyondanyforeseeablecompetition

➨  Decaycanbefullyreconstructed➨  Fullangularanalysispossible

q  Alsosensitivetonewphysics:BS→µ+µ-

◆  NonefoundyetattheLHC(~50events)

●  Expectafew1000’sbytheendofLHC◆  BS→τ+τ- is250timesmoreabundant

●  ButalmosthopelessattheLHC◆  Again,FCC-eeisbeyondanyforeseeablecompetition

●  Several100,000eventsexpected–reconstructionefficiencyunderstudy

28 March 2018


B0→ K* (892) τ+τ-

~SM

-



Synergies

Patrick Janot

Physicscomplementarity/synergy(examples)q  Higgsphysics

◆  FCC-eefixesHiggswidth,HZZcouplings,andttZcouplings(andmanyothers)◆  FCC-hhmeasuresratios-of-BRandgiveshugestatisticsofttZ,ttH,andHHevents

●  FortopYukawacouplingandHiggsselfcoupling,inparticular◆  Combinationcanfind/ruleoutstrong1storderEWPT(candidateforbaryogenesis)

q  Searchforheavyphysics◆  FCC-eegivesprecisionmeasurementssensitivetoheavyphysicsupto…100TeV

●  PatternsofdeviationsmaypointstospecificBSM◆  FCC-hhgivesaccesstodirectobservationatunprecedentedmassesandpT’s

●  AlsohugesamplesofZ,W,Higgs,top

q  Heavyneutrinos◆  FCC-ee:powerfulandclean,butflavourblind:Z→νN,allνflavourstogether◆  FCC-hh:moredifficult,butpotentiallyflavoursensitive:W→l1(Q1)N,N→l2(Q2)W*

q  Flavour“anomalies”(iftheypersist–richflavourphysicsprogrammeotherwise)◆  FCC-eebeyondanyforeseeablecompetitionwithinB→K(*)τ+τ- andBS→τ+τ-

◆  FCC-hhgivesdirectaccesstoZ’gaugebosonsandleptoquarks

q  QCD◆  FCC-eegivesαSto±0.0002(RlforZandW),butalso100kH→gg(gluonfragmentation)◆  FCC-ehprovidesstructurefunctionsandasimilarprecisiononαS

◆  ImprovessignalandbackgroundpredictionsfornewphysicsdiscoveryatFCC-hh


41

5×1012 Z

5×1013 W

Patrick Janot

Futuresynergy:TowardsFCC-µµ?q  Whyhigh-energymuoncolliders?

◆  Muonsareleptons:Canaprioridoallwhatelectronscando◆  Muonsareheavy:Smallcircularcollidersuptolarge√s(SPS/LHC/FCC:6/28/100TeV)◆  Muonsdecay:Ultra-precisebeamenergymeasurement◆  OpenthewaytoprecisionstudyofparticlesobservedbytheFCC-hh

●  Spectrum,masses,couplings,processes,…uptoverylargemasses(√s/2)●  SimilartoCLIC,ifnewparticleswereobservedbytheLHCintheTeVrange


42

(FromCLICstudy:SUSYspectrum)

Patrick Janot

Futuresynergy:TowardsFCC-µµ?q  Recentintriguingapproachtomuoncollider:LEMMA

◆  Producelowemittancemuonbeamswithe+e-→µ+µ- atproductionthreshold◆  Thethresholde+energyforµ+µ- productiononathintarget(e-)is…43.7GeV!

●  CanusetheFCC-eee+ring/boosterasµaccumulationandinternaltargetring➨  (OrtheFCC-eeRFinstalledintheLHCtunnel,orintheFCC-ehERL)➨  Requiresane+sourceabout20timesmoreintensethanFCC-ee/CLIC

●  Allmuonsareproducedwith~thesameenergy,inthesamedirection➨  Nomuoncoolingneeded(ΔE/E~0.07%at√s=6TeV)

●  Transverseemittance500×smallerthanwithprotonsontarget+cooling(MAP)➨  TwoordersofmagnitudelessmuonsneededforsameluminosityasMAP

Lowerbackgroundfrome±inthedetector(frommuondecays)Lowerradiationhazardfromneutrinointeractionsatthesurface

➨  MAPswerelimitedto√s=4TeVtocopewithregulationsonCERNsite


43

LEMMAcangoto√s>20TeV(intheFCCtunnel)withinthesameregulations

Patrick Janot

Futuresynergy:TowardsFCC-µµ?q  Example:FCC-hhdiscoverMSSMHiggseswithmA,H~1.55TeV

◆  ScantheAandHpolesProduceeitherAorHwithtransversepolarization

UniqueCP(violation)andH/Amixingstudies◆  FromH,A→τ+τ-→π+π-ντντFromH,A→τ+τ-→ρ+ρ-ντντwithρ±→π±π0


44

128 E. Eichten, A. Martin / Physics Letters B 728 (2014) 125–130

Table 1Properties of the H and A states in the Natural Supersymmetry benchmark model[44]. In addition to masses and total widths, the branching ratios for various decaymodes are shown. For this benchmark point, tanβ = 23a.

H A

Mass 1.560 TeV 1.550 TeVWidth 19.5 GeV 19.2 GeV

(Decay) Br (Decay) Br

(bb) 0.64 (bb) 0.65

(τ+τ−) 8.3 × 10−2 (τ+τ−) 8.3 × 10−3

(ss) 3.9 × 10−4 (ss) 4.0 × 10−3

(µ+µ−) 2.9 × 10−4 (µ+µ−) 2.9 × 10−4

(tt) 6.6 × 10−3 (tt) 7.2 × 10−3

(gg) 1.4 × 10−5 (gg) 6.1 × 10−5

(γ γ ) 1.1 × 10−7 (γ γ ) 3.8 × 10−9

(Z 0 Z 0) 2.6 × 10−5 (Z 0γ ) 4.3 × 10−8

(h0h0) 4.4 × 10−5

(W +W −) 5.3 × 10−5

(τ±1 τ∓

2 ) 9.2 × 10−3 (τ±1 τ∓

2 ) 9.5 × 10−3

(t1 t∗1) 3.1 × 10−3 (t1 t∗

2) 1.1 × 10−3

(χ01 χ0

1 ) 2.6 × 10−3 (χ01 χ0

1 ) 3.2 × 10−3

(χ02 χ0

2 ) 1.3 × 10−3 (χ02 χ0

2 ) 1.1 × 10−3

(χ01 χ0

3 ) 2.8 × 10−2 (χ01 χ0

3 ) 3.9 × 10−2

(χ01 χ0

4 ) 1.7 × 10−2 (χ01 χ0

4 ) 4.0 × 10−2

(χ02 χ0

3 ) 3.8 × 10−2 (χ02 χ0

3 ) 2.7 × 10−2

(χ02 χ0

4 ) 4.0 × 10−2 (χ02 χ0

4 ) 1.5 × 10−2

(χ±1 χ∓

2 ) 5.7 × 10−2 (χ±1 χ∓

2 ) 6.0 × 10−2

a For tanβ = 10 (5), the branching ratio to muons drops by a factor of 4 (15),while the branching fraction increases by a factor of 1.3 for tanβ = 30.

include gaussian beam-energy smearing with a resolution param-eter R = 0.001. As can be seen from the top panel of Fig. 2, thepeak signal is more than an order of magnitude larger than thebackground.

We use this channel to study the ability of extracting separateinformation about the two nearby resonances. We fit the cross sec-tion in this region by a sum of background, σB given by:

σB(√

s) = c1(mHmA)

s(8)

and one or two Breit–Wigner’s (Eq. (1)) for the signal contribu-tions.

The resulting fits are shown in Table 2. A single Breit–Wigner iscompletely ruled out while the two resonance fit provides an ex-cellent description of the total cross section and allows an accuratedetermination of the individual masses, widths and Bbb branchingratios of the A and H .7

As can be seen in Fig. 1, a large H/A signal to background ratioat a muon collider is fairly independent of mH/A , provided H/A arenarrow and assuming s has been tuned to mH/A . The separabilityof the signal into two distinct resonances, however, is more modeldependent because depends on the overall H/A mass, and the ra-tio of the H/A mass difference &mH/A to the width ΓH/A . Themass sets the overall rate, and thereby the number of events one

7 Note that interpreting the improved fit as evidence for a 2DHM Higgs sectorrequires some caution: a scenario with three resonances where two of the threestates are degenerate (or a similar configuration with more than three resonances)would generate the same rate vs.

√s shape as H/A.

Fig. 2. Pseudo-data (in black) along with the fit results in the bb (top) and τ+τ−

(bottom) channels. The two Breit–Wigner components (A in green, H in red) alongwith the background component (yellow) are also shown. In each bin, the expectednumber of events – the PYTHIA cross section times 5 fb−1 was allowed to fluctuateaccording to Poisson statistics. (For interpretation of the references to color in thisfigure legend, the reader is referred to the web version of this article.)

Table 2Fit of the H/A region to background plus Breit–Wigner resonances. Both a sin-gle and two resonance fits are shown. General form of the background fit isσB (

√s) = c1(1.555)2/s (in TeV2). The values of the best fit for one or two Breit–

Wigner resonances are given.

Mass (GeV) Γ (GeV) σpeak (pb)

One resonance1555 ± 0.1 GeV 24.2 ± 0.2 1.107 ± 0.0076χ2/ndf = 363/96 c1 = 0.0354 ± 0.0006

Two resonances1550 ± 0.5 GeV 19.3 ± 0.7 0.6274 ± 0.05741560 ± 0.5 GeV 20.0 ± 0.7 0.6498 ± 0.0568χ2/ndf = 90.1/93 c1 = 0.040 ± 0.0006

can fit, while &mH/A/ΓH/A quantifies how much the resonancesoverlap.

To study the separability, we performed a small Monte Carlostudy. Specifically, we created pseudodata by randomly draw-ing a fixed number of events from a truth distribution madefrom two Breit–Wigner lineshapes with a given width-to-massand mass-difference-to-width ratio. We then compared a fit tothe pseudodata using a single resonance to a fit from two sepa-rate resonances. If the difference in χ2 between the double- and

δE/E=0.1%

tanβ=20

E. Eichten, A. Martin PLB 728 (2014)125

Polarization: overview

fermions: longitudinal Lz = 0 ⇒ Sz = Jz

⇒⇐

⇒⇐ J = 0: Higgs channels; Jz = ±1: continuum

fermions: transverse

⇑ ⇓⇑⇓ (anti)parallel spins: ↔ CP-even/CP-odd Higgs ch.

⇑ ⇓⊙ orthogonal spins: ↔ triple products (CP-odd obs.)

Federico von der Pahlen, Fermilab, November 2009 – p. 11

µ+ µ-Parallelspins:producesHAntiparallelspins:producesA

F. Palhen et al. JHEP 0808:030 JHEP 0801:017

5

Fig. 1. The π+π− acoplanarity distribution (angle φ∗) in the Higgs boson restframe. The thick line denotes the case of the scalar Higgs boson and thin line thepseudoscalar one.

Fig. 2. The π+π− acollinearity distribution (angle δ∗) in the Higgs boson rest frame.Parts of the distribution close to the end of the spectrum; δ∗ ∼ π are shown. Nosmearing is done. The thick line denotes the case of the scalar Higgs boson and thethin line the pseudoscalar one.

π+π- acollinearity H

A

9

Fig. 5. The ρ+ρ− decay products’ acoplanarity distribution angle, ϕ∗, in the restframe of the ρ+ρ− pair. A cut on the differences of the π± π0 energies defined intheir respective τ± rest frames to be of the same sign, selection y1y2 > 0, is used inthe left plot and the opposite sign, selection y1y2 < 0, is used for the right plot. Nosmearing is done. Thick lines denote the case of the scalar Higgs boson and thinlines the pseudoscalar one.

Fig. 6. The ρ+ρ− decay products’ acoplanarity distribution angle, ϕ•, in the restframe of the ρ+ρ− pair. A cut on the differences of the π± π0 energies definedin their respective replacement τ± rest frames to be of the same sign, selectiony1y2 > 0, is used in the left plot and the opposite sign, selection y1y2 < 0, is usedfor the right plot. All smearing is included. Thick lines denote the case of thescalar Higgs boson and thin lines the pseudoscalar one.

ρ+ρ- acoplanarity

A A H H

y+y- > 0 y+y- > 0

y± = Eπ±-Eπ0

Feasible??



HE-LHC,CLIC,ILC,CEPC?

Patrick Janot

HE-LHCasafirststepfortheFCC-hh?q  PhysicspotentialexploredintheCERNworkshoponHL/HE-LHCphysics

◆  High-massreach~2×MLHC

◆  Higgsself-coupingδλH~±30%◆  Higgsproperties,topandEWobservables:understudy

◆  Instead,withthecomplementaritiesandsynergiesshowntoday

q  WhatdoestheHE-LHCpracticallyentail?◆  EmptytheLHCtunnel(moretimeandCHFthanremovingLEP)◆  Fullreplacementofthemagnets(whosecosttoday>costofLHCmagnets)◆  UpgradeofRFcryogenics,collimation,beamdumps◆  MajorupgradeoftheSPStoinjectat1TeV,possiblywithSCmagnets◆  Majoroverhaulofdetectors


46

https://arxiv.org/abs/1802.04319

Obvioustheorem:Physics(HE-LHC⨂FCC-hh)≡Physics(FCC-hh)

Physics(FCC-ee⨂FCC-hh)>Physics(FCC-ee+FCC-hh)>Physics(FCC-hh)

TimewithoutphysicsatCERNwithHE-LHC>7years

TimewithoutphysicsatCERNwithFCC-ee:NONE

Patrick Janot

HE-LHCasafirststepfortheFCC-hh?q  Cost–notallowedtogivenumbersjustasyet,butarithmetic'siseasy

◆  BuildingHE-LHCislikebuildingtheLHCex-novo–andmore(SPS)●  It’sveryunlikelytobecheaper

◆  Today’sestimatesshowthat,forthecollider,Cost(HE-LHC)~2to3×Cost(FCC-ee)●  MayarguethattheFCC-eeneedsanewtunnelinaddition…

➨  butsodoestheFCC-hh

q  StrategicvalueofHE-LHConthewayto100GeV◆  TheHE-LHCdelaysFCCby~25years,andweakensthecaseforFCCintwoways

●  ItreducestherelativecaseforFCC-hh(smaller√sincrement)●  ItreducestheabsolutecaseforFCC(noFCC-ee)

◆  ItleavesCERNvulnerabletothepossibilitythatafrontiercolliderisbuiltelsewhere●  WithworseperformancethanFCC●  ButstillsufficienttorenderthecaseforFCCmuchmoredifficulttomake

◆  Itkeepsphysicistsdoingphysicswiththesametechniquesformanymanyyears●  After30yearsofLHCandHL-LHC,andbefore30yearsofFCC-hh●  ItmightnobeaveryhealthyplantomaintainCERNattractiveness


47

Cost(HE-LHC+FCCtunnel+FCC-hh)>Cost(FCCtunnel+FCC-ee+FCC-hh)

Patrick Janot

So…FCC-eeasafirststep?q  Physicsabsolutelyneedane+e-EWfactorywith90<√s<400GeV

◆  Fivee+e-colliderstudiesontheplanet(ILC,CLIC,CEPC,LEP3,FCC)inthisrange!●  FCC-eecoversthewholerange:Z,W,H,andtop.

➨  withthehighestluminosities(10×ILCat250GeV,105×LEPat90GeV)➨  withuniquediscoverypotentialtoveryhighscaleandverysmallcouplings➨  technologicallyreadytoday–futureR&Dcanonlyimprovethecase➨  wellaffordablewithinCERNconstantbudgetoncethetunnelisfunded

◆  Muchhardertomakeaconvincingphysicscasefore+e-colliderswith√s>400GeV●  PossibilitythatnewphysicsbefoundbytheendofLHCRun2/3isgettingthin●  Explorationoftheenergyfrontierbestdonewithahadroncollider(e.g.,FCC-hh)

◆  CannotcontinueindefinitelywithR&Dtowardsallpossiblefuturefacilities●  Achoicewillhavetobemadein2019-2020

q  TheFCC-eeisthebestfirststepforFCC-hh1.   Itgivesapreviewofthenewphysicstobesearchedfor,uptoascaleof100TeV2.   ItsignificantlyreducessystematicuncertaintiesonmanyFCC-hhmeasurements

3.   ItprovideshandlestounderstandtheunderlyingtheoryuponparticlediscoveryattheFCC-hh4.   Itprovidestheinfrastructure(tunnel,experimentalshafts,cryogenics,…)atreasonablecost5.   Itbuystimetodevelop16T(or–whynot?–20T)magnetsforFCC-hhatlowercost6.   ItcanevenbeaspringboardforaFCC-µµ (circularµ+µ- colliderwith√s=6,28,or100TeV?)


48

Patrick Janot

Asuccessfulmodel!q  Backtothefuture…

◆  DidthesepeopleknowthatwewouldberunningHL-LHCinthesametunnelmorethan60yearslater?


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e+e-1989-2000

pp2010-2039

Let’snotbeshy!TheFCCsareshapingupasthemostnatural,complete,andpowerfulaspirationofHEPforitslong-termfuture

physics opportunities with the fcc - dpnc.unige.chdpnc.unige.ch/seminaire/talks/janot.pdf ·...

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