Standard Model and New Physics in the Higgs Sector: The New Precision Era

Transcription

1 Standard Model and New Physics in the Higgs Sector: The New Precision Era David López Mateos (Harvard University) Yale NPA Seminar, January 7 th, 6

2 Introduction: the Higgs Discovery [*] arxiv:8.9 Hints of where the Higgs could e existed from precision physics In, the Higgs was found in decay channels, H ZZ and H γγ

3 The Fundamental Physics Context of the Higgs What is the cosmological context of the Higgs? Cosmological history Inflation h Dark matter Matter/anti-matter asymmetry Precision Higgs physics has enormous potential to solve some cosmologically relevant questions 3

4 The Legacy of Run - ln Λ c g Overall: µ =.7. SM expected H γγ +.38 ggf: µ = median limits +.7 VBF: µ = WH: µ = Aout 4 papers sumitted y on the full Run dataset on Higgs physics +3.7 ZH: µ = Overall: µ = pp H γ γ, s = 8 TeV,.3 f Individual analysis internal -. H WW* +.9 ggf: µ = VBF: µ = Standard Model To understand what we can do with Run data, I will focus on three VH: µ = 3.key aspects % CL +.43 Overall: µ = H ττ % CL ggf: µ = of the Run results:. The mass measurement H ZZ* 4l discriminant BDT ZZ.5 s = 7 TeV, 4.5 f. s = 8 TeV,.3 f New physics searches in the Higgs sector σ.5 σ BDT discriminant µ ggf Data Signal J + = SM H ZZ* s = 8 TeV,.3 f.6 s = 7 TeV, 4.5 f s = 8 TeV,.3 f Background ZZ*+Zjets.4 H WW* (ggf+vbf+vh). The measurement of its ranching ratios. 3σ [p] BDT Analysis BR(a τ τ ) P σ(gg H) BR(H aa).8.4 VH V m a = 5 GeV Oserved 95% CL H µµ Median Expected 95% CL ± σ H Zγ ± σ SM gg H tth ZH: c γ µ s = 7 TeV, f s = 8 TeV,.3 f [GeV] m H ggf+tth: µ = VBF+VH: µ = Overall: µ = VBF+VH: µ = Overall: µ = WH: µ = = Overall: µ = Overall: µ = : µ = Multilepton: µ = γγ: µ =.3.75 (GeV) m H Input measurements ± σ on µ 4 Signal strength (µ) 4

5 The Detector High precision silicon and micro-tue tracking Fine-granurality/longitudinally segmented calorimeter Air-core toroid muon spectrometer 5

6 The calorimeters η=.7 EM liquid argon Calorimeter η= Scintillating Tile Hadronic Calorimeters η=- η=.7 η=4.9 Liquid argon Forward Calorimeters Liquid argon Hadronic end-cap Calorimeters Read-out in several segments along shower development Fine position resolution in electromagnetic calorimeter 6

7 The calorimeters η=.7 EM liquid argon Calorimeter η= Scintillating Tile Hadronic Calorimeters calorimeter jet η=- η=.7 Calorimeter shower Liquid argon Forward Calorimeters Liquid argon Hadronic end-cap Calorimeters η=4.9 π, K, etc Read-out in several segments along shower development Fine position resolution in electromagnetic calorimeter particle jet quark/gluon 7

8 The Legacy of Run - ln Λ c g pp H γ γ, s = 8 TeV,.3 f Individual analysis internal SM expected H γγ median limits -. H WW* +.9 ggf: µ = VBF: µ = Standard Model To understand what we can do with Run data, I will focus on three VH: µ = 3.key aspects % CL +.43 Overall: µ = H ττ % CL ggf: µ = of the Run results: BDT Analysis.8.The mass measurement Data H ZZ* 4l s = 8 TeV,.3 f.5 P +.6 Signal J = SM s = 7 TeV, 4.5 f s = 8 TeV,.3 f Background ZZ*+Zjets.4 H WW* (ggf+vbf+vh). The measurement of its ranching ratios. 3σ discriminant BDT ZZ s = 7 TeV, 4.5 f. s = 8 TeV,.3 f New physics searches in the Higgs sector σ.5 σ BDT discriminant µ ggf [p] BR(a τ τ ) σ(gg H) BR(H aa) H ZZ* VH V m a = 5 GeV Oserved 95% CL H µµ Median Expected 95% CL ± σ H Zγ ± σ SM gg H tth +.7 Overall: µ = ggf: µ = VBF: µ = WH: µ = ZH: µ = Overall: µ = ggf+tth: µ = VBF+VH: µ = Overall: µ = VBF+VH: µ = Overall: µ = WH: µ =. -.6 ZH: c γ µ s = 7 TeV, f s = 8 TeV,.3 f [GeV] m H +.5 = Overall: µ = Overall: µ = : µ = Multilepton: µ = γγ: µ =.3.75 (GeV) m H Input measurements ± σ on µ 4 Signal strength (µ) 8

9 Measuring m H : experimental challenges Mass measurement comes from H γγ and H ZZ 4l (e or μ) measurements - H ZZ 4l has virtually no ackgrounds - H γγ has smooth ackground Electron, photon and muon energy scale and resolution determination (.-.5% for electron scale systematic uncertainties!) α. Electrons, η <.6.5. J/ψ ee Z ee Caliration uncertainty s=8 TeV, Ldt=.3 f E T [GeV] 9

10 The Higgs Mass Measurement and CMS Run Total Stat. Syst. LHC Total Stat. Syst. H γ γ 6. ±.5 ( ±.43 ±.7) GeV CMS H γ γ 4.7 ±.34 ( ±.3 ±.5) GeV H ZZ 4l 4.5 ±.5 ( ±.5 ±.4) GeV CMS H ZZ 4l 5.59 ±.45 ( ±.4 ±.7) GeV +CMS γ γ 5.7 ±.9 ( ±.5 ±.4) GeV +CMS 4l 5.5 ±.4 ( ±.37 ±.5) GeV [*] arxiv: CMS γ γ +4l 5.9 ±.4 ( ±. ±.) GeV m H [GeV] Dominant uncertainties all related to electron/photon reconstruction 5- MeV Higgs mass determined to.% accuracy and statistically dominated!

11 The value of m H : implications new physics new physics [*] arxiv: higher energy arxiv: At high scales (~ 9 TeV), Higgs potential changes sign, our universe is in a local minimum, ut hasn t had time to tunnel into the true minimum Metastaility challenged y inflationary cosmology Hints of new physics (ut not enough for TeV-scale new physics)

12 The Legacy of Run - ln Λ c g pp H γ γ, s = 8 TeV,.3 f Individual analysis internal SM expected H γγ median limits -. H WW* +.9 ggf: µ = VBF: µ = Standard Model To understand what we can do with Run data, I will focus on three VH: µ = 3.key aspects % CL +.43 Overall: µ = H ττ % CL ggf: µ = of the Run results: discriminant BDT ZZ.5 σ BDT discriminant µ ggf H ZZ* VH V m BDT Analysis.8 a = 5 GeV Oserved 95% CL H µµ. The mass measurement Data H ZZ* 4l s = 8 TeV,.3 f.5 P +.6 Median Expected 95% CL Signal J = SM H Zγ s = 7 TeV, 4.5 f ± σ s = 8 TeV,.3 f Background ZZ*+Zjets.4 ± σ SM gg H tth H WW*.The measurement of its ranching (ggf+vbf+vh). ratios 3σ s = 7 TeV, 4.5 f. s = 8 TeV,.3 f New physics searches in the Higgs sector σ [p] BR(a τ τ ) σ(gg H) BR(H aa) Overall: µ = ggf: µ = VBF: µ = WH: µ = ZH: µ = Overall: µ = ggf+tth: µ = VBF+VH: µ = Overall: µ = VBF+VH: µ = Overall: µ = WH: µ =. -.6 ZH: c γ µ s = 7 TeV, f s = 8 TeV,.3 f [GeV] m H +.5 = Overall: µ = Overall: µ = : µ = Multilepton: µ = γγ: µ =.3.75 (GeV) m H Input measurements ± σ on µ 4 Signal strength (µ)

13 Branching Ratios: what couples to the Higgs initial state (i) H final state (f) What we measure 3

14 Measuring ranching ratios: H. Kinematic discriminant uilt using machine learning Events / s = 8 TeV Ldt =.3 f lep., jets, Medium+Tight tags p V < GeV T Higgs 6 Data VH() (µ=.) Dioson tt Single top Multijet W+hf W+cl W+l Z+hf Uncertainty Pre-fit ackground VH() 6 [*] arxiv:49.6 Data/Pred BDT VH 4

15 Measuring ranching ratios: H. Kinematic discriminant uilt using machine learning. Many analysis regions (38) to fit different ackground normalizations and shapes 3. Final results from a likelihood fit, including theoretical and experimental systematic uncertainties measurement μ=.5±.3(stat.)±.4(syst.) Events /. Higgs 6 Data/Pred s = 8 TeV Ldt =.3 f lep., jets, Medium+Tight tags p V < GeV T Data VH() (µ=.) Dioson tt Single top Multijet W+hf W+cl W+l Z+hf Uncertainty Pre-fit ackground VH() BDT VH Z+jets W+jets ttar [*] arxiv:49.6 Events / s = 8 TeV Ldt =.3 f lep., jets, Medium+Tight tags p V < GeV T Data VH() (µ=.) Dioson tt Single top Multijet Z+hf Z+cl Uncertainty Pre-fit ackground VH() 8 Events 3 6 s = 8 TeV Ldt =.3 f lep., jets, tag 5 p V > GeV T 4 3 Data VH() (µ=.) Dioson tt Single top Multijet W+hf W+cl W+l Z+l Uncertainty Pre-fit ackground VH() 6 Events / s = 8 TeV Ldt =.3 f lep., 3 jets, Medium tags p V < GeV T Data VH() (µ=.) tt Single top Multijet W+hf W+cl Uncertainty Pre-fit ackground VH() 7 5 Data/Pred BDT VH Data/Pred MVc() OP Data/Pred BDT VH 5

16 Branching Ratios: what couples to the Higgs Assume no invisile Higgs decays and only SM physics in loops m m Coupling κ v F or κ v V F to Higgs V 3 4 and CMS LHC Run Preliminary µ Oserved SM Higgs oson τ W Z t [*] -CONF-5-44, CMS-PAS-HIG5- Particle mass [GeV] Consistent with SM Higgs couplings to osons and fermions 6

17 Can we see new physics in Branching Ratios? σ(gg H ZZ) σ VBF /σ ggf σ WH /σ ggf σ ZH /σ ggf σ tth /σ ggf WW ZZ BR /BR γγ ZZ BR /BR ττ ZZ BR /BR ZZ BR /BR and CMS Preliminary LHC Run CMS +CMS ± σ ± σ Th. uncert Parameter value norm. to SM prediction [*] -CONF-5-44, CMS-PAS-HIG5- gluon-gluon fusion (ggf): tth: g g g g t t t t t t t H H Depending on how we interpret our measurements, there are certain tantalizing deviations, which will e clarified y Run measurements 7

18 The Legacy of Run - ln Λ c g pp H γ γ, s = 8 TeV,.3 f Individual analysis internal SM expected H γγ median limits -. H WW* +.9 ggf: µ = VBF: µ = Standard Model To understand what we can do with Run data, I will focus on three VH: µ = 3.key aspects % CL +.43 Overall: µ = H ττ % CL ggf: µ = of the Run results:. The mass measurement H ZZ* 4l discriminant BDT ZZ.5 σ BDT discriminant µ ggf H ZZ* s = 7 TeV, 4.5 f. s = 8 TeV,.3 f New physics searches in the Higgs sector σ.5 Data Signal J + = SM s = 8 TeV,.3 f.6 s = 7 TeV, 4.5 f s = 8 TeV,.3 f Background ZZ*+Zjets.4 H WW* (ggf+vbf+vh). The measurement of its ranching ratios. 3σ [p] BDT Analysis BR(a τ τ ) P σ(gg H) BR(H aa).8.4 VH V m a = 5 GeV Oserved 95% CL H µµ Median Expected 95% CL ± σ H Zγ ± σ SM gg H tth +.7 Overall: µ = ggf: µ = VBF: µ = WH: µ = ZH: µ = Overall: µ = ggf+tth: µ = VBF+VH: µ = Overall: µ = VBF+VH: µ = Overall: µ = WH: µ =. -.6 ZH: c γ µ s = 7 TeV, f s = 8 TeV,.3 f [GeV] m H +.5 = Overall: µ = Overall: µ = : µ = Multilepton: µ = γγ: µ =.3.75 (GeV) m H Input measurements ± σ on µ 4 Signal strength (µ) 8

19 Searching for New Particles in the Higgs Sector Composite Higgs Electroweak aryogenesis (matter/antimatter asymmetry) Dark matter (invisile decays) Supersymmetry - Good dark matter candidate - Potential for aryogenesis - Solves the hierarchy prolem - Very many parameters to tweak - Very well studied 9

20 Searching for New Particles in the Higgs Sector Higgs doulet models necessary for a variety of new physics models - Higgs doulets: H and H - Both can acquire a vev: tanβ=v/v - 4 new degrees of freedom, 4 more Higgs particles: H, A, H ±, heavier than discovered particle, h tan β ///////////// Os., h couplings [κ V, κ u, κ d ] Exp. Os., A/H ττ Exp. Os., A Zh ll/νν Exp. + Os., H τ ν Exp. Os., H ZZ 4l, ll qq//νν Exp. Os., H WW lν qq/lν Exp. Os., H hh 4, γ γ /τ τ, WWγγ Exp. s=7 TeV, f s=8 TeV, f hmssm, 95% CL limits [*] arxiv: [GeV] m A Complementary information from new particle searches and coupling measurements

21 What we know from Run A Higgs oson has een found that looks very similar to the SM Higgs oson with mh=5 GeV Spin- (spin- ruled out at 99.9% CL), CP-even (arxiv:4.344, ) Mass points to a metastale vacuum, which might e unstale with current understanding of inflation, which implies new physics (ut not necessarily at TeV scale) Experimentally, couplings are determined indirectly to osons and 3rd generation fermions and mostly consistent with SM expectations Coupling measurements are capale of constraining new physics, ut not yet with precision No other new physics ovious

22 What we can do with Run data Factor of 5 luminosity (expect aout 3 f y the end of 6) Cross section ratios: 3/8 TeV Large increase in production cross sections of interesting processes

23 Preparing for Run Data: the Detector New detector complementing the pixel detector Upgraded trigger to cope with khz rate at level (including changes in calorimeter reconstruction) 3

24 Detector Changes and Hadronic Final States [*] ATL-PHYS-PUB-5- Fractional JES uncertainty s = 3 TeV, 5 ns Preliminary anti-k t EM+JES + in situ, R =.4 η =. Total uncertainty Total uncertainty, Asolute in situ JES () Relative in situ JES (scaled ) Flav. composition Flav. response Pileup, predicted 5 conditions Punch-through, predicted 5 conditions to 5 extrapolation uncertainty p jet T 3 [GeV] [*] ATL-PHYS-PUB-5-5 Improvements in capailities to identify -jets due to IBL Changes on the calorimeter manageale: small systematic uncertainties right from the start 4

25 Preparing for Run Data: New Tools pt H =67 GeV H pt H =4 GeV H pt H =36 GeV H Higher energy implies more Ws/Zs/tops and Higgs oson with high pt (reconstructed as one jet) 5

26 pt H =67 GeV H Preparing for Run Data: New Tools [radians] φ Preliminary Simulation Z h+z,; p Z h T =3 GeV fraction p [GeV] T - pt H =36 GeV H H H y p T 3 Higher energy implies more Ws/Zs/tops and Higgs oson with high pt (reconstructed as one jet) 6

27 Events / GeV Significance s = 8 TeV,.3 f Preparing for Run Data: New Tools Data Background model.5 TeV EGM W', c =. TeV EGM W', c =.5 TeV EGM W', c = Significance (stat) Significance (stat + syst) WZ Selection [TeV] m jj [radians] φ Preliminary Simulation Z h+z,; p Z H h T =3 GeV H y fraction p [GeV] p T T - 3 Higher energy implies more Ws/Zs/tops and Higgs oson with high pt (reconstructed as one jet) Tantalizing excesses from Run needed early understanding of these new tools for finding oosted ojects 7

28 Preparing for Run Data: New Tools [radians] 6 5 Preliminary Simulation Z h+z,; p h T =3 GeV fraction p T φ 4 Z 3 [GeV] H H y p T 3 Higher energy implies more Ws/Zs/tops and Higgs oson with high pt (reconstructed as one jet) Tantalizing excesses from Run needed early understanding of these new tools for finding oosted ojects 8

29 Run Data 6 and 7 Cross section ratios: 3/8 TeV Z SSM (3 TeV): stat. increase stat. increase Run End of 6 End of Run x x 3 Searches for exotic particles important early on Complex analyses and those limited statistically in Run most important in 7 and 8 9

30 What we can do with Run data We will e ale to see the H with high significance We may also oserve the direct coupling of the Higgs and the top Both measurements will require: - Maintaining high precision reached in Run in hadronic physics - Clever use of new techniques (oosted regime) 3

31 Measuring H : Run Improvements H H Higgs-jet efficiency..8 Simulation Preliminary anti-k t R=. jets Trimmed (f =.5, R =.) cut su η <. det Loose Selection Efficiency Jet Scale Jet Resolution -tagging Total.6.4 pt H =67 GeV pt H =4 GeV. H Relative Uncertainty [GeV] p T pt H =36 GeV Early H tagger developed and systematic uncertainties estalished 3

32 Measuring H : Run Improvements interpretation interpretation signal H ackground pt H =4 GeV Looking at oth large and small jets provide insight into emergent properties of jets That insight can e used to exploit differences etween signal and ackgrounds 3

33 H Measurement and HDM Implications pmssm models [*] arxiv:38.97 tan β ///////////// Os., h couplings [κ V, κ u, κ d ] Exp. Os., A/H ττ Exp. Os., A Zh ll/νν Exp. + Os., H τ ν Exp. Os., H ZZ 4l, ll qq//νν Exp. Os., H WW lν qq/lν Exp. Os., H hh 4, γ γ /τ τ, WWγγ Exp. s=7 TeV, f s=8 TeV, f hmssm, 95% CL limits [*] arxiv: μh [GeV] m A H coupling has large constraining power over SUSY But also the same final state can e used to look for new Higgs osons with high reach! 33

34 Boosting the Higgs Sector: A tt W qq -quark t Capale of strong constraints on minimal SUSY using just Higgs searches Analyses using new oosted techniques (tops) important for high-mass searches 34

35 Run 3 and HL-LHC: implications for Higgs Physics 5-% measurements can e otained in all accessile decays and couplings Better than Higgs factories (ILC), in certain cases High precision, in case no new physics was found, could point in the direction for where to look Simulation Preliminary s = 4 TeV: Ldt=3 f ; Ldt=3 f H µµ H ττ H ZZ H WW H Zγ H γγ (com.) (incl.) (tth-like) (VBF-like) (com.) (VH-like) (tth-like) (VBF-like) (ggf-like) (com.) (VBF-like) (+j) (+j) (incl.) (com.) (VH-like) (tth-like) (VBF-like) (+j) (+j) µ/µ 35

36 Pile-up: an old enemy 36

37 Pile-up: an old enemy Event Energy Density [GeV] Pile-up already depositing aout 5 GeV of energy in our jets in Run Tracking provides us with powerful handles for pile-up rejection In HL-LHC we expect times as much pile-up as in Run!! (effectively as much energy as in heavy ion collisions at the LHC) 37

38 Hardware solutions for high pile-up 38

39 Hardware solutions for high pile-up New forward tracker critical for pile-up rejection in the forward region Very important for all analyses with neutrinos in final state and forward jets (tth, vector oson fusion Higgs ) 39

40 Event reconstruction for high pile-up Improvements in calorimeter reconstruction also needed Particle-level techniques exist, ut not clear that they work at the detector level 4

41 Conclusions The consequences of the Higgs discovery (and its properties) are still resonating across the theoretical community The Higgs mass was the first instance of Higgs precision physics, ut much more is to come during Run Hadronic final states stand to make huge progress in Run, due to the increased statistics, which will allow for 5σ oservations, and exploiting new techniques Nice complementarity exists etween coupling measurements and new physics searches, and this still needs to e studied in detail for hadronic final states of the Higgs The HL-LHC will provide precision measurements that even some Higgs factories will e unale to repeat, ut with a new detector to uild a lot of challenges remain ahead 4