Recent results in Higgs studies and BSM searches at the LHC Dezső Horváth

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1 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 1 Recent results in Higgs studies and BSM searches at the LHC Dezső Horváth horvath.dezso@wigner.mta.hu Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest & Institute of Nuclear Research (Atomki), Debrecen ELTE Particle Physics Seminar, Budapest Originally presented at QCD@LHC, Dresden, 2018 on behalf of the CMS Collaboration

2 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 2 Outline The Higgs boson BEH mechanism and the Higgs boson Observation at LHC Production and decay channels Couplings to fermions and bosons Problems of the standard model Supersymmetry: the solution? Simplified and natural Search status, 2018 Extended BEH sector? The 750 GeV bump Exotica: summary Acknowledgement: Supported by half the world including Hungarian NKFIH Grants

3 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 3 The Zoo of the Standard Model 3 fermion families: 1 pair of quarks and 1 pair of leptons in each 3 kinds of gauge bosons: the force carriers + the Higgs boson (!) All identified and studied!

4 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 4 Standard Model fitting, 2018 Expt theory uncertainty Measurements by all experiments Left: global EW fit Right: fit w/o measured value of given parameter All within statistics J. Haller et al, arxiv:

5 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 5 Production of the SM Higgs boson in p-p collisions at LHC g q H g gluon fusion q q _ q W,Z _ q H vector boson fusion

6 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 6 Production of the SM Higgs boson in p-p collisions at LHC (Run 2) D. de Florian et al. [LHC Higgs Cross Section Working Group], Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector, arxiv:

7 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 7 Decay of the SM Higgs boson At 125 GeV many decay processes compete. Best identified ( M/M = 1 2%): H ZZ l + l l + l (l = e,µ): BR = , S/B > 1) H γγ: BR = , S/B 1 LHC Higgs Cross Section Working Group, arxiv:

8 LHC and its main experiments Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 8

9 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 9 ATLAS vs. CMS Both optimized to detect (and study!) H γγ and H ZZ 4l. Very different detectors giving very similar results. ATLAS CMS Magnet toroid + small(?) 2 T solenoid large 3.8 T solenoid Tracker semiconductor + TRD semiconductor E-m calorimeter LAr with steel and Pb PbWO 4 scint. Hadron cal.-m. steel + scint. tiles brass + scint. tiles Far forward h-cal LAr with Cu and W steel with quartz Cher. Muon detector chambers (4 types) chambers (3 types) Size 25 m 46 m (23000 m 3 ) 15 m 21.6 m (3800 m 3 ) Trigger 3-level 2-level Weight 7000 t t Participants (sci)

10 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 10 CMS vs. ATLAS: Run 1 masses Combined ATLAS + CMS Higgs-boson mass (Run 1): ± 0.21(stat) ± 0.11(syst) GeV Phys. Rev. Lett. 114 (2015) ; arxiv: CMS (2017): ± 0.20 ± 0.08 PDG (2018): ± 0.16

11 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 11 CMS vs. ATLAS: Higgs mass Mass averaged for two production and all decay channels CMS, 2013: ± 0.3(stat) ± 0.3(syst) GeV/c CMS, 2014: ± 0.27 (stat) ± (syst) GeV/c ATLAS, 2013: ± 0.2(stat) ± +0.5 (syst) GeV/c2 0.6 ATLAS, 2014: ± 0.37(stat) ± 0.18(syst) = ± 0.41 GeV/c 2 Gain in systematics, loss in statistics.

12 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 12 Is it really the SM Higgs boson? relative signal strengths µ = expt/theory in Run 1 Excellent agreement in all channels for both experiments [ATLAS and CMS Collaborations, 5113 authors], JHEP 1608 (2016) 045.

13 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 13 H 4l Invariant mass spectra at s = 13 TeV ± 0.36(stat) ± 0.05 (syst) ± 0.20(stat) ± 0.08 (syst) ATLAS, arxiv: Both statistically limited. CMS, JHEP 1711 (2017) 047

14 A CMS event: H γγ candidate Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 14

15 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 15 H γγ, Run 2 (2016 data) ± 0.21(stat) ± 0.34 (syst) ATLAS, Phys. Lett. B 784 (2018) ± 0.2(stat) ± 0.2(syst) GeV CMS, arxiv:

16 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 16 H W + W 3rd most significant decay channel for the 125 GeV Higgs boson: observed and studied. When in 2012 added to γγ and 4l, increased the observed significance for ATLAS from 5σ to 6.1σ and decreased it for CMS to 4.9σ. ATLAS, Run 1: 6.8σ and µ = CMS, Run 1: 4.8σ and µ = ATLAS + CMS in Run 1: µ = [ATLAS and CMS Collaborations], JHEP 1608 (2016) 045.

17 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 17 ATLAS & CMS: H τ + τ, Run 1 ATLAS: 4.4σ (3.3σ expected), µ = CMS: 3.4σ (3.7σ expected), µ = ATLAS + CMS: 5.5σ (5.0σ expected), µ = 1.09 ± 0.11 (gen.) [ATLAS and CMS Collaborations], JHEP 1608 (2016) 045.

18 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 18 CMS: H τ + τ, Run 2 Local p-value: Prob. that the observed excess is due to random background fluctuations. Signal 13 TeV: 4.9σ, strength µ = TeV: 5.9σ [CMS Collaboration], Observation of the Higgs boson decay to a pair of tau leptons, Phys. Lett. B 779 (2018) 283

19 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 19 CMS & ATLAS, signal strengths Production rate (cross section) ratios: µ i = σ i /(σ i ) SM (i = ggf, VBF, WH, ZH, tth) Relative decay rates (ratios of branching fractions): µ f = B f /(B f ) SM (f = ZZ, WW, γγ, ττ, bb, µµ) Production and decay cannot be separated, what is really measured: µ f i = σ i B f (σ i ) SM (B f ) SM = µ i µ f Allowing for BSM interpretation: σ i B f = σ i (κ) Γ f (κ)/γ H Γ H,Γ f : total and frac. decay widths, Coupling modifiers: κ 2 j = σ j/σj SM (prod.); κ 2 j = Γj /Γ j SM (decay) [ATLAS and CMS Collaborations], JHEP 1608 (2016) 045.

20 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 20 CMS & ATLAS, signal strengths, Run 1 µ = 1.09 ± 0.07(stat) ± 0.04(expt) ± 0.03(thbgd) { }(thsig) [ATLAS and CMS Collaborations], JHEP 1608 (2016) 045. σ(ggf)!

21 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 21 Production channels: CMS, H γγ σ eff : 68.3% σ HM : FWHM/2.35 Best-fit average signal strength (at a floating H mass): µ = (σ BR) meas /(σ BR) SM = } } } 1.18 (stat.) (syst.) (theo.) { { CMS, arxiv: , 2018 {

22 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 22 Coupling modifiers, Run 1 EW vs. QCD production QCD vs. EM decay [ATLAS and CMS Collaborations], JHEP 1608 (2016) 045.

23 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 23 ATLAS & CMS: coupling mod s, Run 1 Coupling to fermions & bosons: per expt. and average per decay mode [ATLAS and CMS Collaborations], JHEP 1608 (2016) 045.

24 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 24 CMS: H bb All prod. channels: VH, gluon fusion, VBF, tth All LHC energies: 7, 8 and 13 TeV Signal excess 5.6σ (5.5σ expected) µ = σ/σ SM = The CMS Collaboration: Observation of Higgs boson decay to bottom quarks, CMS PAS HIG

25 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 25 CMS: tth production , all channels 5.2σ observed, 4.2σ expected, µ = CMS, Phys. Rev. Lett. 120, (2018)

26 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 26 Mass of the top quark: vacuum stability G. Degrassi, S. Di Vita, J. Elias-Miro, J. R. Espinosa, G. F. Giudice, G. Isidori and A. Strumia, Higgs mass and vacuum stability in the Standard Model at NNLO, JHEP 1208 (2012) 098 How stable is our EW vacuum? Depends on the masses of the Higgs boson and of the top quark

27 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 27 Measuring the mass of the top quark CMS Collaboration, Measurement of the top quark mass in the all-jets final state at s = 13TeV CMS-PAS-TOP

28 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 28 Problems of the Standard Model 1 Gravity? S = 2 graviton? Asymmetries: right left World Antiworld Artificial mass creation: Higgs-field ad hoc Charge quantization: Q e = Q p, Q d = Q e /3 Why the 3 fermion families? Nucleon spin: how 1/2 produced? 19 free parameters (too many??): 3 couplings: α, Θ W, Λ QCD ; 2 Higgs: M H, λ 9 fermion masses: 3 M l, 6 M q 4 parameters of the CKM matrix: Θ 1, Θ 2, Θ 3, δ QCD-vacuum: Θ

29 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 29 Problems of the Standard Model 2 Neutrino mysteries M ν > 0 +3 masses, +4 mixing matrix The SM does not like them... What makes them oscillate? Are they Majorana particles ν ν? Gravitational mass of the Universe: 4% ordinary matter (stars, gas, dust, ν) 23% invisible dark matter (out of SM!) 73% mysterious dark energy Naturalness (hierarchy): The mass of the Higgs boson quadratically diverges due to radiative corrections. Cancelled if fermions and bosons exist in pairs.

30 Many-many different models Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 30

31 Beyond the Standard Model Y. Gershtein et al., Working Group Report: New Particles, Forces, and Dimensions, arxiv: Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 31

32 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 32 Supersymmetry (SUSY) Hypothesis: Fermions and bosons exist in pairs: Q F>= B>; Q B>= F> m B = m F Identical particles, just spins different Broken at low energy, partners: much larger mass? SUSY should solve many problems

33 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 33 SUSY: Higgs sector 2 Higgs doublets masses to upper and lower fermions Extended left right asymmetry: m L = m R, but m L m R 8 Higgs fields 5 Higgs bosons: h 0,H 0,A 0,H ± Higgs-parameters: tanβ = v 1 /v 2, masses Mass hierarchy: heavy gluino, light (?) scalar top quark

34 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 34 LSP = dark matter? SUSY s quantum number: R parity R = ( 1) 3B L+2S (B: baryon charge, L: lepton charge, S: spin) R = +1 particle, R = 1 SUSY partner Parity-like: R 2 = +1 If R conserved, lightest SUSY particle (LSP) is stable R parity may not be much violated: we would detect LSP decays Neutral LSP: excellent dark matter candidate

35 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 35 SUSY: coupling constants Minimal Supersymmetric Standard Model: Unification! Bend at low energies: SUSY enters with many new particles more loop corrections

36 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 36 Natural SUSY? Light ( 1 TeV) SUSY particles help to eliminate the hierarchy problem and keep the lightest Higgs-boson light ( h 0 MSSM = H SM). Heavy SUSY particles add huge 2nd-order (log) corrections, ruining the hierarchy elimination. Unfortunately, naturalness is less and less probable as the lower limits on SUSY masses grow. E.g., t is assumed to be the lightest squark, now having m( t) 1 TeV, and a possible decay of the gluino is to t t...

37 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 37 CMS SUSY summary plot, 2017 Simplified Model Spectrum (SMS) topologies

38 CMS limits, 2018: gluino pairs Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 38

39 CMS limits, 2018: squark pairs Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 39

40 CMS SUSY limits, 2018: EW prod. Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 40

41 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 41 ATLAS SUSY summary plot, 2017 Xu, Da (Blois 2017)

42 ATLAS SUSY summary plot, 2018 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 42

43 CMS: search for exotica Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 43

44 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 44 The 750 GeV/c 2 excess in 2015 X γγ CMS: Barrel-barrel and barrel-endcap

45 CMS event: M γγ = 745 GeV Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 45

46 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 46 Excess at 750 GeV/c 2, December 2015 Local p-value: Probability that the observed excess is due to random background oscillation ATLAS, 13 TeV: 3.6σ CMS, TeV: 3.0σ

47 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p GeV excess: excitement ends ATLAS and CMS, end of 2015, Spring 2016: Let us have more data! Theory: avalanche of papers for interpretation: 2015: 150, 2016: 350 papers World press: Death of the standard model?! Excited waiting for new data at start of LHC in M γγ 750 GeV blinded in both experiments. Unblinding for ICHEP, Chicago (July 2016). The excess disappeared in the SM background Be careful about discoveries (both unexpected and expected)!

48 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 48 Conclusion We have observed the Standard Model Higgs boson or (unfortunately, much less probably) a Higgs boson of a more general model. All measured properties are consistent with the predictions for the SM Higgs-boson with a mass of 125 GeV. Let us hope for some deviation from the Standard Model (although none seen yet). The simplest SUSY models do not seem to be supported by experimental data (g-2, LEP, WMAP, LHC,...) The promising 750 GeV diphoton resonance was background oscillation. We are looking for and hoping to find new physics (Dark Matter!) at the LHC. Thanks for your attention!

49 Spare slides for questions Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 49

50 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 50 The SM Higgs boson Production decay cross sections depend on masses only E.g. of decay to fermion pair: Γ(H ff) = N cg 2 m 2 f 32πm 2 W β 3 m H N c colours (leptons: 1; quarks: 3) g SU(2) coupling β 2 = 1 4 m2 f m 2 H fermion velocity. SM limits its mass: 30 GeV < m H < 500 GeV (unitarity) If SM is perturbative to E GUT = GeV: (GUT: Grand Unification Theory) 130 GeV < m H < 190 GeV

51 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 51 CMS: H τ + τ, Run 2 VBF: µτ h, eτ h, eµ All other channels [CMS Collaboration], Observation of the Higgs boson decay to a pair of tau leptons, Phys. Lett. B 779 (2018) 283

52 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 52 Experimental limits, constraints No SUSY phenomenon observed, the data limit the parameter space LEP, Tevatron, LHC: Higgs sector Mass of SM Higgs from direct searches M H = 125 GeV; H h 0 Fitting electroweak data Search for neutral Higgs bosons (h and A) BR(b sγ) measurements at B-factories Anomalous magnetic moment of the muon (BNL) Satellite expts WMAP and Planck: density of dark matter (DM), indirect Direct searches for DM with ν-detectors and AMS2

53 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 53 MSSM mass spectrum: preconceptions Even if we remain sceptic it is worthwhile to know what do most of the model constructors think (after S.P. Martin) R parity is barely violated LSP: χ 0 1 or gravitino Gluino mass M 3 m( g) m( χ 0 1 ),m( χ0 2 ),m( χ± 1 ) m(ũ i ) m( d i ) m( c i ) m( s i ) m( l i ) m(ũ i ) m( d i ) m( c i ) m( s i ) > (0.6 MSUGRA GMSB )m( g) m(ũ L ) m(ũ R )...m( s L ) m( s R ) and m(ẽ L ) m(ẽ R ),m( µ L ) m( µ R ) as M 2 L M2 R + 0,5m2 1/2. t 1, b 1 lightest squarks and τ 1 lightest charged slepton (mixing, Higgs coupling) m(h 0 ) 150 GeV m(a),m(h ± ),m(h 0 )

54 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 54 Simplified Models Few on-shell particles, simple topology and decays Not model-independent, but possibly associated with several models. Possible new physics on well understood SM-base What can we learn of such analysis? Boundaries of search sensitivity, both for data analysis and for new theories. Characterizing new physics signals: what models can be associated? Limits on more general models: from possible cross-sections.

55 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 55 CMS strategies for discovery α T search for early discovery in (forced) 2-jet events (E T (J 1 ) > E T (J 2 )): Cut α T = E T(J 2 ) = M T (J 1,J 2 ) E T (J 2 ) (ET (J 1 )+E T (J 2 )) 2 (p x (J 1 )+p x (J 2 )) 2 (p y (J 1 )+p y (J 2 )) 2 Exclusive 2-jet, inclusive 3-jet search Jets + H T for > 2 jets, inclusive Scalar mom. sum: H T = i p T (J i) ; Missing transverse mom.: MHT = H T = i p T (J i) Razor search: test kinematic consistency for pair production of heavy particles Two jets (inv. mass M R ) + 0 or 1 lepton

56 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 56 Minimal Supersymmetric SM Electroweak symmetry breaking MSSM-fermions mix into mass eigenstates {Electroweak gauginos + higgsinos} {charginos and neutralinos } { } { B(= γ), W ±, W 0 (= Z); h 0, H 0, H }} ± χ ± 1, χ± 2 ; χ0 1, χ0 2, χ0 3, χ0 4 (mass grows with index) Lightest SUSY particle (LSP) depends on model, e.g. msugra: χ 0 1 or GMSB: gravitino ( G) SUSY breaking (how?) many (> 100) new parameters masses, couplings, mixing angles Lots of model variants, huge parameter space, different constraints invented.

57 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 57 The missing MSSM menagerie Kind spin R parity gauge eigenstate mass eigenstate Higgs bosons 0 +1 H 0 1,H0 2,H+ 1,H 2 h0,h 0,A 0,H ± ũ L,ũ R, d L, d R same squark 0-1 s L, s R, c L, c R same t L, t R, b L, b R t 1, t 2, b 1, b 2 ẽ L,ẽ R, ν e same slepton 0-1 µ L, µ R, ν µ same τ L, τ R, ν τ τ 1, τ 2, ν τ neutralino 1/2-1 B 0, W 0, H 0 1, H 0 2 χ 0 1, χ0 2, χ0 3, χ0 4 chargino 1/2-1 W ±, H + 1, H 2 χ ± 1, χ± 2 gluino 1/2-1 g same goldstino 1/2-1 G same gravitino 3/2

58 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 58 Search for other (heavier) Higgs bosons SM extensions predict more Higgs-like bosons. Minimal Supersymmetric SM: 2 BEH-doublets, 8 fields, 5 Higgs-bosons h 0, H 0, A 0, H ± Higgs-like parameters: masses and vacuum exp. values: tanβ = v 2 /v 1 h 0 should be close to H SM, M(H 0 ) M(h 0 ) LEP excluded all below M(W). Above? Popular model: hmssm where h 0 H SM Some links to hundreds of papers: ATLAS Collaboration: CMS Collaboration:

59 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 59 Hunting the Higgs boson Compose a complete SM background using Monte Carlo simulation taking all types of possible events normalized to their cross-sections. Higgs signal: simulation of all possible production and decay processes with all possible Higgs-boson masses Put all these through the detector simulation to get events analogous to the measured ones. Optimize the event selection: reduce B background, enhance S signal via maximizing e.g. N S / N B or N S / N S + N B or see the approximate formula of G. Cowan et al. [ Calculate at experimental luminosity the expected nr. of events for signal and background at various conditions. SM background experiment? (YES / NO ).

60 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p. 60 Search for charged Higgs bosons Just two examples from the 13 TeV exclusion plots ν) [pb] τ ± ± BR(H ) ± σ(pp [b]th 1 10 ATLAS s = 13 TeV, 3.2 fb 1 Observed (CLs) Expected (CLs) ± 1 σ ± 2 σ + H hmssm tanβ= [GeV] + m H M. Aaboud et al. [ATLAS Collaboration], Search for charged Higgs bosons produced in association with a top quark and decaying via H ± τν using pp collision data recorded at s = 13 TeV by the ATLAS detector, Phys. Lett. B 759 (2016) 555 A. M. Sirunyan et al. [CMS Collaboration], Search for charged Higgs bosons produced in vector boson fusion processes and decaying into a pair of W and Z bosons using proton-proton collisions at sqrt(s) = 13 TeV, arxiv: [hep-ex].

61 Dezső Horváth: Higgs and BSM physics at LHC ELTE Theo-Phys. Sem., Budapest, 31 Oct 2018 p GeV excess: strange features X(750) γγ: S X = 0 vagy S X = 2. Scalar? Decays to photons only, why not to ff and WW, ZZ? For a scalar (Higgs-like) boson WW and ZZ dominate. Fifth interaction governs its decay? It does not fit in the Standard Model! Plus: ATLAS sees wide peak, CMS a narrower one.