Tim Barklow (SLAC) BSM Higgs Workshop @ LPC, Fermilab Nov 3, 2014 - - PowerPoint PPT Presentation

Tim Barklow (SLAC) BSM Higgs Workshop @ LPC, Fermilab Nov 3, 2014

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≤ ≤ ≤ = International Linear Collider linear collider with SCRF lin ILC ac 250 1000 GeV 31 km length ( 500 GeV) 49 km length ( 1000 GeV) e e s s s

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≤ ≤ = = Compact Linear Collider linear collider with X-Band linac RF powered by a 2nd drive beam 350 3000 GeV 13 km length ( 500 GeV) 48 km lengt CLIC h ( 3000 GeV) e e s s s

Overview of Future e+e- Facilities

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FCC Future Circular Collider at CERN, 80 -- 100 km circumference tunnel

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≤ ≤ ≤ ≤ Future Circular Collider, mode (Formerly known as ) 91 350 GeV Future Circular Collider, mode 3.5 4.9 TeV Future Circular Collider, m FCC-ee TLEP FCC-

• de

Known gener he FCC-hh ically VLHC as e e s pe s pp s = 100 TeV

Circular collider study in China with 50 km circumference tunnel:

= ≤ ≤ CEPC S Circular Electron Positron Collider 240 GeV Super proton proton Collider 50 TeV 70 TeV ppC s s

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µµ

, WW l l l e ν ν µ → = , ZZ l l l l l e µ

+ − + −

→ =

Discovery decay modes at LHC

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• ⇒ ∆

∝

• →

  All background is electroweak. Roughly, the detection efficiency is independent of decay mode ( ) / 1/ The Higgs recoil measurement of ( ) provides model independent me BR BR BR e e ZH σ σ σ Γ asurements

• f the Higgs BR's and

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Higgs Coupling Measurements at Colliders - Generalities e e

SM Higgs BR

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

i 33

Model independent global coupling fit using 32 measurements and measurement

ZH

BR Y Y σ σ

The cross section calculations do not involve QCD ISR. The partial width calculations do not require quark masses as input. We believe that the total theory errors for and will be at the 0

i i i i

S G S G .1% level in 10-15 years.

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Higgs Coupling Measurements at Colliders - Generalities e e

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Overview of Higgs Physics at Colliders for e e

= = = 250 GeV (ILC, FCC-ee,CEPC) 350 GeV (ILC, CLIC, FCC-ee) 500 GeV (ILC, CLIC) =1000 GeV (ILC, CLIC) s s s s

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( ) 250 GeV e e ZH s σ

+ − →

=

, H anything, incl invisible Z e e µ µ

+ − + −

→ →

− −

∆ = ∆ ∆ = ∆

1 1

ILC: M .032 GeV, / =2.5% for L= 250 fb M .015 GeV, / =1.2% for L=1150 fb

H HZ HZ H HZ HZ

σ σ σ σ

2 1

/ 1.3% (0.6%) for L=250 (1150) fb

HZ HZZ HZZ HZZ

g g g σ

−

⇒ ∆ = 

Higgs Recoil Measurement of Higgs Mass and Higgstrahlung Cross Section

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× → = BR measurements using 250 GeV e e ZH s σ

All Z decays are used for measurement

• f
• BR. These include Z

and Z . qq σ νν × → → Flavor tagging very important for distinguishing different decay modes

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 If BF(Hinvisible) = 3%

• Signal is clearly seen for “Right” polarization

“Left” “Right”

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→ → = , Z qq, H invisible 250 GeV e e ZH s

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+ − →

= , H 350 GeV e e ZH s νν

All of the Higgstrahlung studies that were done at 250 GeV can also be done at 350 GeV. Precisions for are comparable, as is the precision for (ZH)

• nce Z

decays are included. fusio = = →  σ σ s s BR q q WW n production of the Higgs at 350 GeV provides a much better measurement

• f

compared to 250 GeV. This gives a much improved estimate of the total Higgs width which in turn significantly i = = Γ

HWW H

s g s mproves the coupling errors obtained from measurements made at 250 GeV. The recoil Higgs mass measurement is significantly worse at 350 GeV with respect to 250 GeV. However, there is hope t = = =  σ BR s s s hat direct calorimeter Higgs mass measurements using will recover the precision.

+ − →νν

e e H

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+ − →

= , H, t t H, ZHH 500 GeV e e ZH s νν

The coupling can also be measured well at 500 GeV through fusion production of the Higgs. Cross section for significantly enhanced near threshold due to tt bound state effects. This

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= →

HWW

g s WW e e ttH

1

leads to a measurement of the top Yukawa coupling / 14% with 500 fb at 500 GeV. The ZHH channel is open at 500 GeV providing some sensitivity to the Higgs self coupling. Search for additional

−

∆ = = =

t t

y y s s Higgs bosons that might have been missed at LHC

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+ − →

≥ H , , 1 TeV e e ttH HH s νν νν

At 1 TeV an collider provides better measurements of the top Yukawa coupling and Higgs self coupling. Search for additional Higgs bosons that might have been missed at LHC. In addition, an

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≥ s e e collider becomes a Higgs factory again since the total Higgs cross section is larger than the total cross sections at 250 GeV, specially if polarized beams are used:

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e e

13  Each scenario corresponds to accumulated luminosity at a certain

point in time.

 Assumption: run for 3X107 s at baseline lumi at each of

Ecm=250,500,1000 GeV, in that order. Then go back and run for 3X107 s at upgrade lumi at each of Ecm=250,500,1000 GeV.

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ILC Measurement Summary

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ILC Model Independent Higgs Coupling ∆Γ =

tot

2.5% 4.9% 2.3%

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7 Parameter HXSWG Benchmark Higgs Coupling Comparison Between LHC and ILC

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Precision improves by more than a factor of 3 going from 500 to 550 GeV

Top Yukawa Coupling Versus s

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Higgs Self Coupling Summary

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ILC LumUp Baseline

• 2 Big Luminosity Advantages of FCC-ee over ILC:

4 IP's Luminosity of FCC-ee grows as is lowered below 250, while ILC luminosity drops off s

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Numbers from "First Look at Physics Case for TLEP", JHEP 01,164(2014) TLEP = 4 exp. @ 240 +350 GeV Numbers from ILC Higgs White Paper, arXiv:1310.0763,

ILC500(LumUp)* 0.3% 0.3% 0.6% 1.4% 1.1% 1.0% 42% 4.4%

Model Dependent Fits (7 Parameter HXSWG Benchmark)

* Includes several 0.1% systematic errors including 0.1% theory error

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Numbers from "First Look at Physics Case for TLEP", JHEP 01,164(2014) TLEP = 4 exp. @ 240 +350 GeV Numbers from ILC Higgs White Paper, arXiv:1310.0763,

ILC500(LumUp) 0.5% 0.6% 0.8% 1.5% 1.2% 1.2% 42% 4.5%

Model Independent fits

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+ − →

= Higgs Self Coupling Measurement at FCC-ee Using NLO Contribution to at 240 & 350 GeV e e ZH s

• M. McCullough, arXiv:1312.3322

= < = Assuming 0 Higgs self coupling can be constrained to | | 28% by FCC-ee at 240 GeV

Z H

s δ δ

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= Measurement of Electron Yukawa Coupling @ 125 GeV? s

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 Due to the unique experimental environment of e+e- machines,

ILC, CLIC and FCC-ee can improve on the excellent Higgs measurements expected from LHC and HL-LHC. They provide a means to bring Higgs coupling precisions from the few percent level to the sub-percent level

 The ILC – the most mature of the future e+e- designs -

provides significant improvement over HL-LHC over a wide range of Higgs couplings.

 CLIC and FCC-ee can take the Higgs coupling measurements

even further, with significant enhancements in energy and luminosity, respectively, relative to the ILC.

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