Measurement of the Higgs boson mass and e+e-  ZH cross section using Zμ+μ- and Ze+e- at ILC √s = 250, 350, and 500 GeV European Linear Collider Workshop May 30 – Jun 5, 2016, Santander, Spain Jacqueline Yan , J. Tian , K.Fujii (KEK) and the ILC Physics Working Group 2013/07/20 ILC@富山 1

Leptonic recoil mass study is finalized @ECM = 250 GeV, 350 GeV, and 500 GeV This study shows clearly the impact of ECM and polarization on the precise measurement of σZH and MH as well as demonstrates model independence to sub-% level Higgs recoil against di-lepton system Based on full ILD detector simulation σZH is essential input to measurement of the pattern in the deviation of couplings in order to discriminate new physics models at the ILC Paper submitted to P.R.D. : arxiv:1604.07524 undergoing review Reference paper on model independence: arxiv:1601.06481 Then I added all other BG and sig processes that hhave been generated as samples, even though I presumed them to be not important for Zmumu analysis at 250 GeV. I wanted to check I didn’t msis anything. I almost didn’t miss anything, except for WW_sl, Some of the quarks may have decayed secondarily into muons, and I left it out. There are about 130 events left after all cuts. While other were mostly 0. The results were only a little different after including this. ILC sample used in analysis channel MH ECM L polarization e+eZh->μμh e+eZh->eeh 125 GeV 250 GeV 350 GeV 500 GeV 250 fb-1 333 fb-1 500 fb-1 P(e-,e+) = (-0.8,+0.3) (+0.8,-0.3)

Data Selection Method Signal signature a pair of isolated energetic leptons (μ/ e) with invariant mass (Minv) close to Z mass Dominant backgrounds Signatures e+ e-  Z Z  l+ l- X : forward Z production angle e+ e-  γ Z  γ l+ l- : energetic ISR γ which balance dilepton pt e+ e-  W W  l+ l- ν ν : broad Minv distr. cuts are designed to achieve high precision and at the same time maximize signal efficiency and minimize bias on Higgs decay modes Final Selection 73 < GeV < M_inv < 120 GeV 10 GeV < pt_dl < (…) GeV |cos(θ_missing)| < 0.98 TMVA cut Evis cut observe spectrum within signal region (depend on ECM) Lepton Pair Candidate Selection Prompt μ/e ID , isolated lepton finder (MVA based) FSR and bremsstrahlung recovery Lepton pairing : minimizeχ2(Minv, Mrec) Here is the data selection I applied, with the numbers from last week Friday. First I select muon pairs based on ratio of deposit in calorimeter wrt to total energy, opposite charge, and track quality. Than I pick out the best muon pair candidates base on how close their inv mass is to real Z mass Next , comes final selection for recoil mass analysis. Here, in the order that these arei implemented I require inv mass to be between 86 and 95 GeV, Then recoil mass to be between 115 and 140 GeV Then PT of dilepton system to be between 10 GeV and 70 geV Then acoplanarity to be between 0.2 and 3 then cosine of Z production angle to be smaller than 0.91, to cut out very forward events characteristic of BG processes, Then I calculate efficieny by counting events in signal region of 123 and 135 geV Recoil mass is calculated taking into account beam x angle of 14 mrad. Last week I received a comment from Kurata san about why I have this lower limicoplanarity Ithe reason is that for some Bgprocesses, teher is a peak at very small cop values, although for the dominant 2f_Z_l, peak is at aroudn pai. However I have doubts as to whether this cut is really necessary, when I already have the other cuts before it. experimented with the outcome s when I take away the lower limit, and when I take away the cop cut altogether. I also experimented with widening the inv maass cut window. 3

Data Selection Performance Example of cut table for 250 GeV, Zμμ Major residual BG: 4f_zz_sl , 4f_zz_l, 2f_z_l ECM=250GeV Zμμ ECM=250GeV Zee Here is the data selection I applied, with the numbers from last week Friday. First I select muon pairs based on ratio of deposit in calorimeter wrt to total energy, opposite charge, and track quality. Than I pick out the best muon pair candidates base on how close their inv mass is to real Z mass Next , comes final selection for recoil mass analysis. Here, in the order that these arei implemented I require inv mass to be between 86 and 95 GeV, Then recoil mass to be between 115 and 140 GeV Then PT of dilepton system to be between 10 GeV and 70 geV Then acoplanarity to be between 0.2 and 3 then cosine of Z production angle to be smaller than 0.91, to cut out very forward events characteristic of BG processes, Then I calculate efficieny by counting events in signal region of 123 and 135 geV Recoil mass is calculated taking into account beam x angle of 14 mrad. Last week I received a comment from Kurata san about why I have this lower limicoplanarity Ithe reason is that for some Bgprocesses, teher is a peak at very small cop values, although for the dominant 2f_Z_l, peak is at aroudn pai. However I have doubts as to whether this cut is really necessary, when I already have the other cuts before it. experimented with the outcome s when I take away the lower limit, and when I take away the cop cut altogether. I also experimented with widening the inv maass cut window.

Reconstructed Recoil Mass Spectrum Sig + BG BG Signal 250 GeV: Zμμ channel Pol: (- 0.8, +0.3) Sig + BG BG Signal 500 GeV 350 GeV Now here is the plot for the fitted recoil mass including all signal and BG samples listed earlier, and after implementing all the cuts. Ifor fitting, I used GPET for signal and 3rd order polynomial for BG. The fitted recoil mass came out to be 125.3 GeV, and the error of this was about 70 MeV. at present stage this fitted mass precision has much meaning , until AFTER I evaluate the validity of my analysis thouroughly using pseudo experiments, by generating Toy MC events.

Reconstructed Recoil Mass Spectrum Sig + BG BG Signal 250 GeV: Zee channel Pol: (- 0.8, +0.3) Sig + BG BG Signal 500 GeV 350 GeV Now here is the plot for the fitted recoil mass including all signal and BG samples listed earlier, and after implementing all the cuts. Ifor fitting, I used GPET for signal and 3rd order polynomial for BG. The fitted recoil mass came out to be 125.3 GeV, and the error of this was about 70 MeV. at present stage this fitted mass precision has much meaning , until AFTER I evaluate the validity of my analysis thouroughly using pseudo experiments, by generating Toy MC events.

Statistical Uncertainties at ECM=250GeV, left pol, assuming 250 fb-1 , ZH xsec relative error at ECM=250GeV, left pol, assuming 250 fb-1 , we can achieve xsec : 2.5% ΔMH : 37 MeV ΔMH (MeV) assumed Lumi: 250 fb-1@250GeV 333fb-1@350GeV 500fb-1@500GeV (for each beam pol) Precision clearly worse at higher energies (at 350 GeV: ΔσZH 1.3 x , ΔMH 2.7 x , at 500 GeV: ΔσZH 2.1 x, ΔMH 14 x) Right pol: BG is suppressed, but precision 〜10% worse due to signal xsec smaller (2/3 x) Then I added all other BG and sig processes that hhave been generated as samples, even though I presumed them to be not important for Zmumu analysis at 250 GeV. I wanted to check I didn’t msis anything. I almost didn’t miss anything, except for WW_sl, Some of the quarks may have decayed secondarily into muons, and I left it out. There are about 130 events left after all cuts. While other were mostly 0. The results were only a little different after including this. ZH xsec: include contribution from invisible Higgs decay T. Junping, https://agenda.linearcollider.org/event/6557/session/12/contribution/129/material/slides/0.pdf A. Ishikawa, http://agenda.linearcollider.org/event/6389/session/0/contribution/140/material/slides/1.pdf

After full H20 run: gZZH: 0.4%, ΔMH : 14 MeV Scaled to H20 Scenario ZH xsec relative error ΔMH (MeV) Then I added all other BG and sig processes that hhave been generated as samples, even though I presumed them to be not important for Zmumu analysis at 250 GeV. I wanted to check I didn’t msis anything. I almost didn’t miss anything, except for WW_sl, Some of the quarks may have decayed secondarily into muons, and I left it out. There are about 130 events left after all cuts. While other were mostly 0. The results were only a little different after including this. After full H20 run: gZZH: 0.4%, ΔMH : 14 MeV

Model Independence Taking Into Account Exotic Decay Modes final efficiency in last row (stat uncertainty = 0.16%) no visible bias beyond 1 sigma observe deviation from avg efficiency Known modes unknown modes : Bx 10% any exotic decay modes should resemble these wide kinematic range of SM modes assign 10% of “unknown mode” BR (2) fluctuate known SM modes by largest BR uncertainty predicted from HL-LHC (Snowmass report arXiv: 1310.8361 ) and ILC for H cc and gg (“ILC Higgs White Paper”, arXiv:1310.0763) Here is the data selection I applied, with the numbers from last week Friday. First I select muon pairs based on ratio of deposit in calorimeter wrt to total energy, opposite charge, and track quality. Than I pick out the best muon pair candidates base on how close their inv mass is to real Z mass Next , comes final selection for recoil mass analysis. Here, in the order that these arei implemented I require inv mass to be between 86 and 95 GeV, Then recoil mass to be between 115 and 140 GeV Then PT of dilepton system to be between 10 GeV and 70 geV Then acoplanarity to be between 0.2 and 3 then cosine of Z production angle to be smaller than 0.91, to cut out very forward events characteristic of BG processes, Then I calculate efficieny by counting events in signal region of 123 and 135 geV Recoil mass is calculated taking into account beam x angle of 14 mrad. Last week I received a comment from Kurata san about why I have this lower limicoplanarity Ithe reason is that for some Bgprocesses, teher is a peak at very small cop values, although for the dominant 2f_Z_l, peak is at aroudn pai. However I have doubts as to whether this cut is really necessary, when I already have the other cuts before it. experimented with the outcome s when I take away the lower limit, and when I take away the cop cut altogether. I also experimented with widening the inv maass cut window. relative bias on σZH < 0.08 % for Zmm < 0.19% for Zee Bias get smaller for higher ECM conclusion: current bias is more than 5 times smaller than even the best statistical uncertainty expected from full H20 run

Summary Completed full simulation study which demonstrates measurement precision of the e+e-  ZH cross section (σZH) and the Higgs boson mass (MH) at the ILC clear comparison established between three ECMs = 250, 350, and 500 GeV, and two beam polarizations (Pe-,Pe+) =(−80%, +30%) and (+80%, -30%)  results may contribute to further optimization of ILC run scenario Assuming Lumi = 250 fb-1 for left pol at ECM = 250 GeV : σZH = 2.5%, ΔMH=37 MeV scaling all results to H20 run: ΔgHZZ/gHZZ = 0.4%, ΔMH = 14 MeV model independence demonstrated to the sub-% level data selection methods designed to minimize bias on σZH to more than 5 times smaller than even the smallest σZH statistical uncertainties Paper submitted to P.R.D. : arxiv:1604.07524 undergoing review Reference paper on model independence: arxiv:1601.06481 Next steps: Study systematic uncertainties due to beam-beam effects Here is the data selection I applied, with the numbers from last week Friday. First I select muon pairs based on ratio of deposit in calorimeter wrt to total energy, opposite charge, and track quality. Than I pick out the best muon pair candidates base on how close their inv mass is to real Z mass Next , comes final selection for recoil mass analysis. Here, in the order that these arei implemented I require inv mass to be between 86 and 95 GeV, Then recoil mass to be between 115 and 140 GeV Then PT of dilepton system to be between 10 GeV and 70 geV Then acoplanarity to be between 0.2 and 3 then cosine of Z production angle to be smaller than 0.91, to cut out very forward events characteristic of BG processes, Then I calculate efficieny by counting events in signal region of 123 and 135 geV Recoil mass is calculated taking into account beam x angle of 14 mrad. Last week I received a comment from Kurata san about why I have this lower limicoplanarity Ithe reason is that for some Bgprocesses, teher is a peak at very small cop values, although for the dominant 2f_Z_l, peak is at aroudn pai. However I have doubts as to whether this cut is really necessary, when I already have the other cuts before it. experimented with the outcome s when I take away the lower limit, and when I take away the cop cut altogether. I also experimented with widening the inv maass cut window.

BACKUP Here is the data selection I applied, with the numbers from last week Friday. First I select muon pairs based on ratio of deposit in calorimeter wrt to total energy, opposite charge, and track quality. Than I pick out the best muon pair candidates base on how close their inv mass is to real Z mass Next , comes final selection for recoil mass analysis. Here, in the order that these arei implemented I require inv mass to be between 86 and 95 GeV, Then recoil mass to be between 115 and 140 GeV Then PT of dilepton system to be between 10 GeV and 70 geV Then acoplanarity to be between 0.2 and 3 then cosine of Z production angle to be smaller than 0.91, to cut out very forward events characteristic of BG processes, Then I calculate efficieny by counting events in signal region of 123 and 135 geV Recoil mass is calculated taking into account beam x angle of 14 mrad. Last week I received a comment from Kurata san about why I have this lower limicoplanarity Ithe reason is that for some Bgprocesses, teher is a peak at very small cop values, although for the dominant 2f_Z_l, peak is at aroudn pai. However I have doubts as to whether this cut is really necessary, when I already have the other cuts before it. experimented with the outcome s when I take away the lower limit, and when I take away the cop cut altogether. I also experimented with widening the inv maass cut window.

Comparison between ECMs and polarizations assume Lumi nearly scales with ECM assumed Lumi: 250 fb-1@250GeV 333fb-1@350GeV 500fb-1@500GeV (for each beam pol) Precision clearly worse at higher energies (esp for MH) ΔσZH is not so bad at ECM=350 GeV Right pol: BG is suppressed, but precision 〜10% worse due to signal xsec smaller x 1.5 scaled to H20 scenario Then I added all other BG and sig processes that hhave been generated as samples, even though I presumed them to be not important for Zmumu analysis at 250 GeV. I wanted to check I didn’t msis anything. I almost didn’t miss anything, except for WW_sl, Some of the quarks may have decayed secondarily into muons, and I left it out. There are about 130 events left after all cuts. While other were mostly 0. The results were only a little different after including this. After full H20 run: gZZH: 0.4%, ΔMH : 14 MeV

Also tried MH measurement using Hbb mode B likelihood: Red: 2f BG Blue : signal MH measurement does not need to be model-independent, If use Hbb mode, the only major residual BG is 4f_zz_sl Zmm 250GeV 250GeV ΔmH [MeV] ΔmH [MeV] (H-->bb) Zmm left 39 38 right 43 Zee 121 106 149 124 350 GeV 103 114 120 125 450 382 502 464 500 GeV 592 530 660 566 1160 1030 1190 1130 B likeliness improvement (10-15%) for Zee at all ECM and both Zmm and Zee ECM=500 GeV (2f BG is more serious for Zee and higher ECM) Here is the data selection I applied, with the numbers from last week Friday. First I select muon pairs based on ratio of deposit in calorimeter wrt to total energy, opposite charge, and track quality. Than I pick out the best muon pair candidates base on how close their inv mass is to real Z mass Next , comes final selection for recoil mass analysis. Here, in the order that these arei implemented I require inv mass to be between 86 and 95 GeV, Then recoil mass to be between 115 and 140 GeV Then PT of dilepton system to be between 10 GeV and 70 geV Then acoplanarity to be between 0.2 and 3 then cosine of Z production angle to be smaller than 0.91, to cut out very forward events characteristic of BG processes, Then I calculate efficieny by counting events in signal region of 123 and 135 geV Recoil mass is calculated taking into account beam x angle of 14 mrad. Last week I received a comment from Kurata san about why I have this lower limicoplanarity Ithe reason is that for some Bgprocesses, teher is a peak at very small cop values, although for the dominant 2f_Z_l, peak is at aroudn pai. However I have doubts as to whether this cut is really necessary, when I already have the other cuts before it. experimented with the outcome s when I take away the lower limit, and when I take away the cop cut altogether. I also experimented with widening the inv maass cut window. 2f BG is greatly reduced, but mass precisions limited by signal statistics merit of this method is not totally clear yet (?)