Study of Higgsinvisible using kinematic fit Yu Kato The Univ. of - - PowerPoint PPT Presentation

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Study of Higgsinvisible using kinematic fit Yu Kato The Univ. of - - PowerPoint PPT Presentation

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Study of Higgsinvisible using kinematic fit Yu Kato The Univ. of Tokyo Asian Physics and Software Meeting Dec. 15, 2017 Improve of recoil mass dist. efficiency: 65.9% significance: 22.3 efficiency: 61.8% significance: 17.0 New

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Study of Higgs→invisible using kinematic fit

Yu Kato The Univ. of Tokyo

Asian Physics and Software Meeting Dec. 15, 2017

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Improve of recoil mass dist.

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Left

significance: 15.5 efficiency: 63.5%

signal bkg

Right

significance: 19.7 efficiency: 65.9%

signal bkg

Previous Result (LCWS2016) New Result w/ kinematic fit

significance: 17.0 efficiency: 61.8% significance: 22.3 efficiency: 65.8%

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Upper Limit of BR(H→inv.) w/ kinfit

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250 fb-1 of each Pol. 250 GeV Stage : 900 fb-1 of each Pol.

UL of BR(H→inv.) = 0.824% (95%CL) UL of BR(H→inv.) = 0.483% (95%CL) UL of BR(H→inv.) = 0.215% (95%CL) UL of BR(H→inv.) = 0.423% (95%CL)

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backup

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Upper Limit of BR(H→inv.) w/ kinfit

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lIn SM, Higgs decays invisibly through H → ZZ∗ → 4& (BR(H → *+,.)~0.1%) lIf BR(H → *+,.) exceeds SM prediction , it signifies new physics beyond SM (BSM) lWe estimate SM upper limit of BR(H → *+,.) lCompare between left & right polarization at the ILC

Motivation

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q q

BSM

X X

invisible

Dark Matter… SUSY…

visible 45 H → XX ~? ? ? %

q q Z Z ν ν ν ν

45 H → ZZ∗ → 4& ~0.1% invisible visible

Ø A. Ishikawa (Tohoku Univ.), ”Search for Invisible Higgs Decays at the ILC” LCWS2014@Belgrade Ø M. A. Thomson (Univ. of Cambridge), arXiv: 1509.02853 (2015)

LHC CMS result (95% CL)

  • bserved (expected)

24% (23%)

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pWe want to improve recoil mass resolution of Higgs->inv. analysis. 898: → ;<, ; → >>, < → *+,*?*@A8

BCDE

F

= ?

  • − JK F − L

⃗K F

pApply kinematic fit

minimize χ2 under constraints => method of Lagrange multipliers

NF = O ⃗PQR − O ⃗SDTU

VW9X O

⃗PQR − O ⃗SDTU + 2[ ⃗V \ ] ⃗

  • measured parameters O

⃗ : J

^X, _`X, a^X, J ^F, _`F, a^F

  • constraint function ]

⃗ : b^X,^F = bK = 91.2 GeV, g^X = |L^X|/J

^X, g^F = |L^F|/J ^F

  • covariance matrix W : jk(J, lm?_), jn(J, lm?_), jo(J, lm?_)

pUse MarlinKinfit

fitter engine : NewtonFitter ( use Newton-Raphson iterative method ) samples : ffH_ZZ_4n { ILD_l4_v02, ILD_s4_v02, (ILD_o1_v05) }

pStatus

  • include jet resolution for each event ( from Z->uds 2jet sample data )
  • recoil mass sigma becomes smaller a little

pPlan

1. apply BW mass constraint & Z natural width 2. consider ISR effect ( e.g. include aa_lowpt overlay) 3. (make my own kinematic fitter based on Kurata-san’s kinematic fitter)

kinematic fit

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