Tim Barklow (SLAC) April 13, 2016 Experimental Challenges for the LHC Run II, KITP

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1 Tim Barklow (SLAC) April 13, 2016 Experimental Challenges for the LHC Run II, KITP

2 Future Circular Collider Study - SCOPE CDR and cost review for the next ESU (2018) Intl. collab. to study: pp-collider (FCC-hh) Ultimate goal, defining infrastructure. ~16 T 100 TeV pp in 100 km ~20 T 100 TeV pp in 80 km e + e - collider (FCC-ee) as potential first step ECM= GeV p-e (FCC-he) option km infrastructure in Geneva area 4-5 Feb

3 FCC-ee possible long-term strategy PSB PS (0.6 km) SPS (6.9 km) LEP LHC (26.7 km) HL-LHC HE-LHC? (33 TeV c.m.) FCC-ee (100 km, e + e -, up to ~380 GeV c.m.) FCC-hh (pp, up to 100 TeV c.m.) 60 years of e + e - pp AA (ep) highest energies B Great synergy and complementarity of FCC-ee and FCC-hh! 4-5 Feb

4 4 4

5 CEPC 5 5

6 Linear Colliders ILC International Linear Collider ee + linear collider with SCRF linac 250 s 1000 GeV 31 km length ( 49 km length ( s 500 GeV) s = 1000 GeV) CLIC Compact Linear Collider ee + linear collider with X-Band linac RF powered by a 2nd drive beam 350 s 3000 GeV 13 km length ( s = 500 GeV) 48 km length ( s = 3000 GeV) 6 6

7 ILC Machine Parameters from TDR Note there are two types of upgrades: Luminosity upgrade: Install extra klystrons and modulators so number of bunches can be doubled; envisioned after 8 years of baseline running Energy upgrade: Increase accel. gradient, lengthen linac, or both. TDR config assumes 49 km. length; envisioned after 20 years of running 7 7

8 Luminosity Upgrade for Ecm=250 GeV The s = 250 GeV lumi is quadrupled by doubling the number of bunches and the collision rep rate The 10 Hz operation which in the baseline was split between 5 Hz collision and 5 Hz e + production is now 100% collision in the lumi upgrade config. A longer undulator should be ready that can produce sufficient e + yield with 125 GeV electrons Note the AC power is 200 MW, the same as the 5 Hz lumi upgrade power at s = 500 GeV Also note that ILC produces 3 10 cm s luminosity with 200 MW total AC power. 8 8

9 ILC Running Scenario 9 9

10 FCC-ee (4 IPs) Baseline CEPC (2 IPs) ILC LumUp 10 10

11 FCC-ee 11 11

12 s = 90, 160 GeV FCC-ee (4 IPs) Baseline CEPC (2 IPs) ILC LumUp Not easy to run the ILC at these energies. e.g. 150 GeV (125 GeV) e beam needed for positron production in baseline (lumi upgrade) design In the lumi upgrade config L=4 91 GeV and L=8 160 GeV. Ldt = Ldt = 1 1 This would provide GeV in 10 mos. and GeV in 10 mos

13 Overview of Higgs Physics at ee + at s = 250,350,500,1000 GeV Colliders 13 13

14 Measurement of σ ( e + e ZH) s = 250 GeV Higgs Recoil Measurement of Higgs Mass and Higgstrahlung Cross Section -- Key to model independent Higgs coupling measurements + + Z ee, µ µ H anything, incl invisible ILC: M =.032 GeV, σ / σ =2.5% for L= 250 fb H HZ HZ M =.015 GeV, σ / σ =1.2% for L=1150 fb H HZ HZ 1 1 σ HZ g 2 HZZ g / g = 1.3% (0.6%) for L=250 (1150) fb HZZ HZZ

15 σ + BR measurements using e e ZH s = 250 GeV All Z decays are used for measurement of σ BR. These include Z qq and Z νν. Flavor tagging very important for distinguishing different decay modes 15 15

16 + e e ZH, Z qq, H invisible s = 250 GeV Left Right 16

17 + e e ZH, νν H s = 350 GeV All of the Higgstrahlung studies that were done at s = 250 GeV can also be done at s = 350 GeV. Precisions for σ BR are comparable, as is the precision for σ(zh) once Z qq decays are included. WW fusion production of the Higgs at s = 350 GeV provides a much better measurement of g compared to s = 250 GeV. This gives a much improved estimate of the HWW total Higgs width Γ H which in turn significantly improves the coupling errors obtained from σ BR measurements made at s = 250 GeV. The recoil Higgs mass measurement is significantly worse at s = 350 GeV with respect to s = 250 GeV. However, there is hope that direct calorimeter Higgs mass measurements using + ee νν H will recover the precision

18 + e e ZH, νν H, t t H, ZHH s = 500 GeV The g coupling can also be measured well at s = 500 GeV through WW fusion HWW + production of the Higgs. Also the measurement of σ ( e e νν H ) BR( H X ) can be made for many Higgs decay modes H X. Through ee + tth the top Yukawa coupling can be measured to y / y = 16.6% 1 with 500 fb at 500 GeV. With same luminosity at 550 GeV the precision is y / y = 6.73 strong motivation to increase nominal energy to t t s = s = t t s = 550 GeV The ZHH channel is open at s 1 to 27% with 4 ab assuming the true value is the SM val = 500 GeV. The Higgs self coupling can be measured ue

19 + e e ννh, tth, νν HH s= 1 TeV At s = 1 TeV the ILC provides better measurements of the top Yukawa coupling and Higgs self coupling. For example the Higgs self coupling can be measured to an accuracy of 1 10% with 4 ab at s = 1 TeV (again, assuming the true value is the SM value). Search for additional Higgs bosons that might have been missed at LHC, and study new resonances below s = 1 TeV that might be seen at LHC In addition, the ILC becomes a Higgs factory again since the total Higgs cross section is larger than the total cross sections at 250 GeV, especially if polarized beams are used: 19 19

20 Summary of ILC Higgs Measurement Precisions From "500 GeV ILC Operating Scenarios" arxiv :

21 ILC Model Independent Higgs Coupling Precisions 8yrs 20yrs 21 21

22 750 GeV DiPhoton Resonance at 1 TeV ILC * γ X Γ ( X ) 10 SM Γ (H ) γγ γγ σ( ee γx ) fb at s= 1 TeV 750 F. Richard, arxiv:

23 5 ab

24 σ σ FCC-ee 1 Errors on and BR from arxiv: assuming GeV with ab : 24 24

25 FCC-ee 25 25

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27 1 Take CEPC errors on σ and σ BR from pre Conceptual Design Report assuming 240 GeV with 5 ab : Take ILC errors on σ and σ BR from arxiv: assuming GeV with ab (H-20 scenario) Perform model independent fit of b,c,g,w, τ,z, γµ,,invis Higgs couplings and total width using standard program (from Michael Peskin) for ILC & CEPC separately and combined

28 Relative Higgs Coupling Error 1 ILC GeV with fb (H-20 scenario at 8.1 yrs) CEPC 250 GeV with 5000 fb 1 ILC + CEPC under the conditions listed above Best g : CEPC CEPC CEPC ILC CEPC CEPC CEPC CEPC CEPC CEPC 28 28

29 Relative Higgs Coupling Error 1 ILC GeV with fb (H-20 scenario full run 20.2 yrs) CEPC 250 GeV with 5000 fb 1 ILC + CEPC under the conditions listed above Best g : ILC ILC ILC ILC ILC CEPC ILC CEPC CEPC ILC 29 29

30 1 ILC GeV with fb (G-20 scenario at 8.1 yrs) CEPC 250 GeV with 5000 fb 1 ILC + CEPC under the conditions listed above How does ILC help CEPC in a situation where CEPC has (mostly) the best individual results? Relative Higgs Coupling Error CEPC g Comb. g Extra CEPC* Running (yr) *Additional CEPC running required to match ILC contribution to Combination. Assumes all extra running at s = GeV

31 Relative Higgs Coupling Error 1 ILC GeV with fb (H-20 scenario full run 20.2 yrs) CEPC 250 GeV with 5000 fb 1 ILC + CEPC under the conditions listed above How does CEPC help ILC in a situation where ILC has (mostly) the best individual results? ILC g Comb. g Extra ILC* Running (yr) *Additional ILC running required to match CEPC contribution to Combinat ion. Assumes all extra running at s = GeV

32 Highlights of Combination of CEPC with ILC 20 yrs g g g g g HZZ HWW Hbb Hττ Hgg CEPC ILC+CEPC 0.26% 0.20% 1.22% 0.26% * 1.30% 0.47% 1.44% 0.65% 1.53% 0.70% * Might be interesting to include σ ( WW H ) in precision Higgs analyses 32 32

33 CEPC Higgs Self Coupling Measurement at Ecm=240 GeV M. McCullough, arxiv: g g hzz hhzz fixed to SM valu e ( δ = 0) fixed to SM value z 240 δ σ δ H = = = % Note : Oft quoted 30% error comes from combining CEPC with 50% HL-LHC meas

34 CEPC Higgs Self Coupling Measurement at Ecm=240 GeV M. McCullough, arxiv: g g hzz hhzz fixed to SM valu e ( δ = 0) fixed to SM value z Examples of BSM physics with δ z 0 : 240 δ σ δ H = = = % Note : Oft quoted 30% error comes from combining CEPC with 50% HL-LHC meas

35 ILC Higgs Self Coupling Measurement at Ecm=500 GeV ghzz fixed to value from σ ( ZH ) measurement g hhzz fixed to SM value See following slides Extract g from measurement of σ ( ZHH ) hhh using HH bbbb & bbw W + σ ( ZHH ) ghhh = 16% = 27% for ILC scenario 20 years. σ ( ZHH ) g hhh ghhh ghhh Note : This assumes SM ghhh. If ghhh = 2 SM then = 27 % = 14 %. g g hhh hhh 35 35

36 ILC Higgs Self Coupling Systematic Error + Unc ertainties for g g in σ ( ee HHZ ) ZZH ZZHH We assume that σ ( e + e HHZ) can be described by an effective field theory (EFT) containing a general SU(2) U(1) gauge invariant Lagrangian with dimension-6 operators in addition to the SM. Using the convention of arxiv: we have, before EWSB, the following dim-6 operators: + other operators that are not relevant or that violate CP Note there are only 8 EFT parameters: ch ct c6 cw cb chw chb c γ 36 36

37 ILC Higgs Self Coupling Systematic Error g g ( j) ( j) The couplings xxx and xxxx take the following form in our EFT: c 6 is uniquely accessible through the Higgs self coupling measurement. The other 7 EFT parameters appear in several places. Note the relationships between the hzz & hhzz couplings. The TGC's depend on, c W HW HB through the Goldstone bosons that are eaten by the Band W fields c, c 37 37

38 The parameters c, c, c are constrained by electroweak precision tests. W B T From arxiv: : ILC Higgs Self Coupling Systematic Error By definition 2 2 MW v cw c,, 2 W ct 2 Λ Λ etc. 3 We will assume in the following that, at the 10 level, c = c c = W B T

39 ILC Higgs Self Coupling Systematic Error The TGC's κ and g are related to EFT parameters by γ κ = g γ Z 1 = c c HW W + Z 1 + c c HB HW At ILC with the full H-20 scenario the error on the TGC's are ( κ ) = 2 10 γ ( g ) = 8 10 Z We can then assume at the 10 level that c W = c HW = c HB (2) (2) so that we can write ghzz and ghww as g g = g c + κ s 0 W g (2) Z 2 2 hzz 2 1 W c M θ γ θ θ W (2) hww W g Z = g1 0 M W 39 39

40 ILC Higgs Self Coupling Systematic Error Through EWPT's and ILC measurements of TGC's the number of independent EFT parameters has been reduced from 8 to just 4: c, c, c, c H γ HW 6 The first two parameters are determined by and (3) ( 3) ghww g hzz (3) relationship between the W coupling ghww and ch is simply (3) hww, the usual Higgs couplings to W and Z that are measured assuming the SM Lorentz structure. The g gm W 1 (1 ch ). 2 The parameter s is given by 4 θ 1 2 (3) (3) 8 W c 2 γ = cθ g W hzz ghww cθ gm W W c γ 40 40

41 ILC Higgs Self Coupling Systematic Error The EFT parameter chw is related to the " b" parameter of the HVV Lorentz structure studies by Fujii, Tian, Ogawa and others done here at KEK: HWW HZZ arxiv: Talk by T. Ogawa at LCWS15 Let b & b be the " b" parameters of the HWW & HZZ analyses respectively. w z (1) bw (1) bz g hww =-2 g hzz =-4 Λ Λ v bw chw = b w for Λ =1 TeV assumed in the analysis 2Λ (3) 1 (3) v 1 1 (3) 1 (3) b z chw = (g 2 hzz g 2 hww ) b z (g 2 hzz g 2 hww ) 1 tθ W gmw cθ Λ t gm W θw W cθ W For full H20 b = 0.18 b = Since b is much better right now we ignore the b w w z z (1) measurement and use ghzz 4 b z bz = = Λ v 41 41

42 ILC Higgs Self Coupling Systematic Error Let's now rewrite the Lagrangian using our measured variables g g g and the one remaining unconstrained EFT parameter (3) (3) (1) hzz hww hzz c 6 L 2 (3) (3) M ghww 7 3 g H g hww µ = + c6 h + 1 h µ h h 2v gmw 8 MW gmw bz µν 1 g (3) µ + Z µν Z h + hzz Z µ Z h 4v 2 b g g z g + Z Z h + + c Z Z h 8v 8c gm gm 2 (3) (3) µν 2 hww 2 hzz µ 2 µν 1 2 θ W µ θ W W W In this EFT approach all of the couplings in the calculation of ( e e HHZ) are tightly constrained by the other Higgs coupling σ + measurements, TGC measurements, and EWPT's. The only unconstrained parameter is c. If the best match to the measured σ ( e + e HHZ) is c 6 6 = 0 within sys+stat errors then we have observed SM Higgs self coupling

43 Other Higgs Measurements with CEPC & ILC H-20 at 20 yrs m g g g g g g H HHH HHH tth tth (*) tth tth CEPC ILC 250 GeV GeV Combined 5000 fb fb MeV 12.5 MeV 5.3 MeV 36 % 27 % 22 % 5.9 % 5.9 % 2.4 % 2.4 % (*) Assumes ILC 500 GeV running actually takes place at s = 550 GeV 43 43

44 1 Take FCC-ee errors on σ and σ BR from arxiv: assuming GeV with ab : Take ILC errors on σ and σ BR from arxiv: assuming GeV with ab (H-20 scenario) Perform model independent fit of b,c,g,w, τ,z, γµ,,invis Higgs couplings and total width using standard program (from Michael Peskin) for ILC & FCC-ee separately and combined

45 1 ILC GeV with ab (H-20 scenario) FCC-ee GeV with ab 1 ILC + FCC-ee under the conditions listed above How does ILC help FCC-ee? Relative Higgs Coupling Error FCC-ee g Comb. g Extra FCC-ee* Running (yr) *Additional FCC-ee running required to match ILC contribution to Combination. Assumes the same 10:2.6 luminosity ratio for 240:350 GeV except ZZ & invis which assume that all extra running is at 240 GeV 45 45

46 1 ILC GeV with ab (H-20 scenario) FCC-ee GeV with ab 1 ILC + FCC-ee under the conditions listed above How does FCC-ee help ILC? Relative Higgs Coupling Error ILC g Comb. g Extra ILC* Running (yr) *Additional ILC running required to match FCC-ee contribution to Combination. Assumes the same 1:2 luminosity ratio for 250:500 GeV except ZZ & invis which assumes all extra running at 250 GeV

47 Highlights of Combination of FCC-ee with ILC H-20 g g g g g HZZ HWW Hbb Hττ Hgg ILC FCC-ee ILC+FCC-ee 0.31% 0.19% 0.16% 0.38% 0.35% 0.22% 0.60% 0.52% 0.38% 0.89% 0.63% 0.49% 0.92% 0.85% 0.61% 47 47

48 Other Higgs Measurements with FCC-ee & ILC H-20 m g g g g g g H HHH HHH tth tth eeh SM eeh FCC-ee ILC GeV (550) GeV Combined ab fb MeV 12.5 MeV 8.3 MeV 29 %* 27 %* 20 % 13% 5.9 (2.4) % 5.4 (2.4) % < 2.2@ 3σ < 2.2@ 3σ * Loop contribution to σ (ZH) * Tree-level contribution to σ ( ZHH) 48 48

49 ILC helps FCC-ee: The 0.25% measurement of σ(ννh)xbr(h bb) reduces errors on all Higgs couplings The 2.4% Top Yukawa coupling measurement from tth production improves upon the 13% measurement from the tt threshold scan. ILC σ(zhh) measurement provides a 27% tree-level determination of the Higgs selfcoupling, and could help clarify a Higgs self-coupling interpretation of the precision FCC-ee σ(zh) measurement. FCC-ee helps ILC: Precision measurement of g HZZ and various σxbr at 240 GeV help turn the ILC 0.25% measurement of σ(ννh)xbr(h bb) into g WW = 0.22% Much better meas. of Higgs invisible width, BSM decays, rare decays such as γγ and µµ Note: BRi = 1 can be used to improve all coupling errors if BR(H BSM) < 1% Unique access to Higgs coupling to 1 st generation fermions. FCC-ee+ILC combination helps the particle physics community: Higgs Z coupling error g HZ = 0.16% Higgs W coupling error g WW = 0.22% Higgs b coupling error g bb = 0.38% Higgs self coupling error g HHH = 20% 49 49