Higgs couplings in CMS in Run-2 Stephane Cooperstein (Princeton) on behalf of the CMS Collaboration 54th Rencontres de Moriond Electroweak unification and unified theories La Thuile, Italy, 16-23 March 2019 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 1
Outline • H → bb ̅ • Observation of H → bb ̅ last summer Results shown today new since � latest Higgs couplings combination, • H → μ + μ - shown at Moriond last year • result with 7+8+13 TeV (2016) data arXiv:1809.10733 Submitted to Eur. Phys. J. C � • top-Higgs coupling • ttH observation last spring with 7+8+13 TeV (2016) data. • Updated results for 2/3 channels with 2017 data: • ttH multilepton (November) Spring/summer � • ttH, H →γγ (November) Fall � � NEW • H → invisible • Combination of all search channels with 13 TeV (2016) data (September) • Combination with 7+8+13 TeV (2016) data (NEW) • most stringent limit on BF(H → inv) 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 2
̅ H → bb Observed: γγ √ γ • BF(H → bb ̅ ) ~ 58% for SM Higgs with m H = 125 GeV. ? √ bb WW � • Inclusive H → bb ̅ search: challenging √ (factor 10 7 - 10 9 higher) multi-bjet ZZ background. √ τ others � • VH, H → bb ̅ most sensitive channel at LHC. • Leptonic V decay provides important handle on background and simple trigger strategy. 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 3
̅ VH, H → bb b-jet • Require high-p T W or Z back- Vector boson to-back with respect to H → bb ̅ candidate. b-jet • Small fraction of inclusive H → bb ̅ events but S/B ~1-10% • Separate channels targeting Z →ℓℓ , Z →νν , and W →ℓν � • New for analysis of 2017 data: • Latest machine learning techniques (DNN) to: • identify b-jets, estimate b-jet energy, differentiate S vs. B • Kinematic fit in Z →ℓℓ channel • taking advantage of unique channel topology (no inherent missing energy) 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 4
H → bb ̅ Combination Phys. Rev. Lett. 121 (2018) 121801 • Including all H → bb ̅ published results from CMS (7+8+13 TeV). • Dedicated searches in ttH, VBF, and ggH production modes as well as VH. Observation of H → bb ̅ by the CMS Collaboration! Significance 5.5 σ exp 5.6 σ obs = 1.04 ± 0.20 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 5
H → µµ • Very rare decay: BF(H → µµ): ~0.022% • Clean experimental signature but large Z/ γ * → µµ background. � • Boosted decision tree (BDT) trained to discriminate S vs. B. • di-muon kinematics for ggH vs. B. • jet kinematics (when applicable) to discriminate VBF H from B. • Μ µµ and mass resolution not used as inputs to avoid biasing background shape. � • Categorize events by BDT score + resolution and fit Μ µµ . 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 6
H → µµ: result with 2016 data • Combination of 7+8+13 TeV (2016) data. • Measurement entirely statistics-dominated. • Approaching sensitivity to Higgs coupling to second generation fermions ! 13 TeV • Benefiting from excellent muon resolution in CMS. (2016 data) • 0.9 σ (expected) with only 35.9 fb -1 13 TeV data. 95% CL UL: σ *BR 2.2 x SM expected 2.9 x SM observed Significance 7+8+13 TeV 1.0 σ expected 0.9 σ observed Phys. Rev. Lett. 122 (2019) 021801 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 7
Top-Higgs coupling • Indirect sensitivity to y t via y t measurement of gluon fusion gluon fusion production. production ( ggH ) • Assuming no BSM particles run in the loop. � � � � • Direct sensitivity to y t via measurement of ttH production (coupling at tree level). top associated y t production ( ttH ) � • σ ttH,13 TeV ~ 510 fb • Factor ~4 increase relative to σ ttH,8 TeV 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 8
̅ ttH measurements in CMS • ttH ~1% total Higgs production benefits/ ttH search channel challenges � • Complex many-particle final states largest rate but combinatorics, H → bb challenging tt ̅ +bb ̅ bkg. lower rate but also multilepton (H → WW*, ZZ* , ττ ) less background very clean but small H →γγ , ZZ(4l) rate 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 9
Observation of ttH • Combination of all channels (bb ̅ , multilepton, γγ ) 7+8+13 TeV (2016 only) � • Direct confirmation of Yukawa coupling to top quarks Observation of ttH production by the CMS Collaboration! Significance 4.2 σ expected 5.2 σ observed Phys. Rev. Lett. 120 (2018) 231801 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 10
ttH multilepton with 2017 data N Significance e w • Events categorized by lepton s ( i + 2017 data only: n c 2 e 0 1 multiplicity as well as lepton flavor/ o 7 1.7 σ (2.9 σ ) b d s a e t r a v charge and b-tagging. � ) a t i o n 13 TeV (2016+2017): � 3.2 σ (4.0 σ ) • Improvements for 2017 analysis: • extended categorization • data-driven ttV modelling � • Dedicated BDT’s trained per category to discriminate signal from background. • Primary backgrounds: non-prompt leptons, ttW, ttZ. CMS-PAS-HIG-18-019 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 11
ttH, H →γγ with 2017 data • Events categorized by BDT score 2016 + 2017 and split by 0 ℓ , ≧ 1 ℓ . � • Fit m γγ to extract signal. � • Improvements for 2017 analysis: • additional categories • improved BDT with additional observables CMS-PAS-HIG-18-018 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 12
ttH, H →γγ with 2017 data: results CMS-PAS-HIG-18-018 • Measurement predominately statistics-limited. Significance • Smaller relative systematic 2017 data only: uncertainty than other ttH channels 3.1 σ (2.2 σ ) � New (+2017 data) 13 TeV (2016+2017): since observation 4.1 σ (2.7 σ ) 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 13
VBF H → invisible • Multiple potential contributions to Γ (H → inv.) • Higgs coupled to BSM particles either: • not detectable (e.g. dark matter) • not yet accessed final states (long-lived, background-dominated signatures,..) � � � • VBF production most sensitive H → inv. channel. • Characteristic signature allows for high suppression of SM backgrounds. 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 14
VBF H → invisible: fit strategy Z( νν )+jets extrapolated from 2-lepton sideband • Dominant backgrounds: Z( νν )+jets and W( ℓ v) +jets. � • Extract Z( νν )+jets and W( ℓ v)+jets shapes from 1- and 2-lepton sidebands and fit m jj . W(l ν )+jets extrapolated from 1- lepton sideband 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 15
H → invisible combination � � � � � ��� � � � � + + ��� � � � � � � � � � � � � �� � � � � �� • Combine independent H → inv. searches on 2016 data: VBF, Z(ll)H, W(q’q)H, ggH. � • Set limits on B inv by assuming SM production rates. � • VBF production channel most sensitive • 2016 VBF-only: B inv < 0.33 (0.25) • O(25%) improvement in sensitivity from adding VH and ggH channels. B inv < 0.26 (0.20) @95% CL 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 16
H → invisible combination: 7+8+13 TeV • Reinterpretation in context of Higgs- NEW RESULT portal models of DM interactions. Most stringent limit to date! � • Most stringent limits for M DM < 18 (7) B inv < 0.19 (0.15) GeV assuming fermion (scalar DM) candidate. arXiv:1809.05937 submitted to Phys. Lett. B C M S s : c a l a r D M : S M C M D n o m i r e f 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 17
H → J/ ψ J/ ψ , H →ΥΥ NEW RESULT • SM BF’s inaccessible by many orders of magnitude. observed expected � • Four-muon final state. 1.8 + 0.2 B ( H → J/ ψ J/ ψ ) × 10 3 1.8 − 0.1 • Experimentally clean with very small SM B ( H → ΥΥ ) × 10 3 1.4 1.4 ± 0.1 backgrounds 2.8 + 1.2 � B ( Z → J/ ψ J/ ψ ) × 10 6 2.2 − 0.7 • Excess at H or Z mass would be sign of B ( Z → ΥΥ ) × 10 6 1.5 1.5 ± 0.1 BSM physics. -1 -1 CMS 37.5 fb (13 TeV) CMS 37.5 fb (13 TeV) Preliminary Preliminary 2 2 10 10 2 2 Events / 3 GeV Events / 3 GeV Events / 4 GeV Events / 4 GeV 10 10 Data Data Background Background Model Boson Signals Model Boson Signals 10 10 10 10 H →ΥΥ H → J/ ψ J/ ψ 1 1 1 1 -1 -1 10 10 -1 -1 10 10 20 20 40 40 60 60 80 80 100 100 120 120 140 140 40 40 60 60 80 80 100 100 120 120 140 140 M M (GeV) (GeV) M M (GeV) (GeV) 4 4 4 4 CMS-PAS-HIG-18-025 µ µ µ µ 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 18
Summary • Third generation Yukawa couplings firmly and directly established. • Observation of ttH and H → bb ̅ in 2018, previous observation of H →ττ . � • Approaching sensitivity to second generation via H → µµ. � • Tightening constraints on H → inv. • most stringent limit: • B inv < 0.19 (0.15) @95% CL � • Working towards improved legacy measurements using full 13 TeV dataset. 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 19
Thank you! 17/03/2019 S. Cooperstein (Princeton) Moriond EW 2019 20
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