After the discovery of a Higgs boson(-like) particle a theorists - PowerPoint PPT Presentation

After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak Albert-Ludwigs-Universit¨ at Freiburg February 21, 2014

Discoveries at the LHC Expectations (2008): ’t Hooft: Gross: Veltman: “A Higgs, or more” “A super world” “The unexpected” After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014

Discoveries at the LHC Expectations (2008): ’t Hooft: Gross: Veltman: “A Higgs, or more” “A super world” “The unexpected” . . . I I I I 4 July 2012 Nov. 2011 13 Dec. 2011 8 Oct. 2013 HCP 2011: Nobel prize: Exclusion of for the theoret. ATLAS & CMS a wide Higgs ATLAS & CMS discovery of announce the mass range, report an excess a mechanism discovery of some theorists’ of events: that contributes a Higgs-like thought: Too early to to our particle “complete draw conclusions understanding exclusion until of the origin of mass . . . the end of 2011” After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014

How was it discovered? Discovery channels (LHC: p p collider, p = proton): pp → H → ZZ ∗ → 4 ℓ : pp → H → γγ : (here: ℓ = µ , µ = muon) ℓ g t g γ Z ℓ H t t H W W ℓ t Z t g W ℓ t g γ After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014

How was it discovered? Discovery channels (LHC: p p collider, p = proton): pp → H → ZZ ∗ → 4 ℓ : pp → H → γγ + 2 jets: (here: ℓ = µ , µ = muon) q q ′′ ℓ g V γ t W Z H ℓ H W t γ W ℓ V Z t g ℓ q ′ q ′′′ After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014

Is it “the” Higgs boson? • Mass: free parameter in the Standard Model expectation from precision measurements: O ( 100 GeV ) (e.g. mass of the W boson) Moriond ’13: CMS: m H = 125.7 ± 0.3 (stat) ± 0.3 (syst) GeV ATLAS: m H = 125.5 ± 0.2 (stat) + 0 . 5 − 0 . 6 (syst) GeV • Spin? Landau-Yang theorem: Massive spin-1 particle cannot decay into two photons: Decay into photons observed ⇒ spin � = 1 Moriond ’13: spin = 2: Excluded with > 99 % confidence level model dependent spin = 0: compatible • CP? Moriond ’13: CP-even: compatible spin = 0 CP-odd: Exclusion with � 98 % confidence level After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014

Is it “the” Higgs boson? • Couplings? so far compatible with the Standard Model: Signal strengths: – Measurement of further production und decay channels: pp → H → WW (compatible with SM) pp → H → ττ (Evidence!) pp → H → bb . . . – still relatively large errors ( ∼ 20 %) – not all couplings accessible After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014

Is it “the” Higgs boson? • Mass: free parameter in the Standard Model : s l e d o m expectation from precision measurements: O ( 100 GeV ) r s e s h y a t m b O (e.g. mass of the W boson) n s . e s g v r g e i g i t H e e m b Moriond ’13: CMS: m H = 125.7 ± 0.3 (stat) ± 0.3 (syst) GeV a n r a a c p r e h ATLAS: m H = 125.5 ± 0.2 (stat) + 0 . 5 t o − 0 . 6 (syst) GeV • Spin? Landau-Yang theorem: Massive spin-1 particle cannot decay into two photons: Decay into photons observed ⇒ spin � = 1 Moriond ’13: spin = 2: Excluded with > 99 % confidence level model dependent spin = 0: compatible a mixture of CP-odd and • CP? Moriond ’13: CP-even: compatible spin = 0 -even? CP-odd: Exclusion with � 98 % confidence level After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014

Is it “the” Higgs boson? • Couplings? so far compatible with the Standard Model: Could be affected by an extended Higgs sector or other unknown particles: – Measurement of further Signal strengths: production und decay channels: how much? pp → H → WW (compatible with SM) pp → H → ττ (Evidence!) pp → H → bb . . . – still relatively large errors ( ∼ 20 %) – not all couplings accessible After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014

Further Results of the LHC Supersymmetric partner particles: • not found yet Summary of CMS SUSY Results* in SMS framework SUSY 2013 m(mother)-m(LSP)=200 GeV m(LSP)=0 GeV ~ g qq ∼ 0 • strongest constraints: → χ SUS-13-012 SUS-12-028 L=19.5 11.7 /fb ~ g qq ∼ 0 → χ SUS-12-005 SUS-11-024 L=4.7 /fb ~ ∼ 0 g → bb χ SUS-13-004 SUS-12-024 SUS-12-028 L=19.3 19.4 /fb ~ ∼ 0 g → tt χ SUS-13-004 SUS-13-007 SUS-13-008 SUS-13-013 L=19.4 19.5 /fb gluino production ~ ∼ 0 + - ∼ 0 g → qq ( χ → l l χ ) SUS-11-011 L=4.98 /fb ~ ∼ 0 2 ∼ 0 ∼ 0 g → qq( χ → τ τ χ | χ ) SUS-12-004 L=4.98 /fb ~ ∼ 2 ∼ ∼ g → qq( χ ± → W χ 0 | χ 0 ) x = 0.25 colour charged particles: SUS-12-010 L=4.98 /fb x = 0.50 ~ ~ ∼ x = 0.75 g → t( t → t χ 0 ) SUS-13-008 SUS-13-013 L=19.5 /fb ~ ∼ ∼ g → qq( χ ± → l ± ν χ 0 ) SUS-11-010 L=4.98 /fb ~ ∼ 0 ∼ 0 g → qq ( χ → Z χ ) SUS-11-021 SUS-12-002 L=4.98 4.73 /fb x = 0.25 x = 0.50 x = 0.75 ~ ∼ 2 ∼ 0 g → qq( χ ± → W χ ) x = 0.20 SUS-13-013 L=19.5 /fb x = 0.50 ~ ∼ 0 ∼ 0 ∼ ± ∼ 0 g → qq( χ → γ χ | χ → W χ ) SUS-12-001 L=4.93 /fb gluinos and 2 ~ ∼ 0 ∼ 0 g → qq( χ → γ χ ) SUS-12-001 L=4.93 /fb ~ ~ ∼ 2 ∼ 0 g → b( b → t( χ ± → W χ )) SUS-13-008 SUS-13-013 L=19.5 /fb squark q ~ q ∼ 0 → χ SUS-13-012 SUS-12-028 L=19.5 11.7 /fb first generation of squarks ~ ∼ 0 q → q χ SUS-12-005 SUS-11-024 L=4.7 /fb ~ ∼ 0 t → t χ SUS-13-011 SUS-13-004 L=19.5 19.3 /fb left-handed top unpolarized top ~ ∼ right-handed top t → t χ 0 SUS-11-024 SUS-12-005 L=4.7 /fb ~ ∼ ∼ t → b( χ + → W χ 0 ) x = 0.25 SUS-13-011 L=19.5 /fb x = 0.50 stop ~ ∼ ∼ x = 0.75 t → b ( χ ± → W χ 0 ) signature: SUS-11-030 L=4.98 /fb ~ t → t b χ ∼ 0 χ ∼ ( 0 → H G) SUS-13-014 L=19.5 /fb ~ ∼ 0 sbottom b → b χ s = 7 TeV SUS-12-028 L=11.7 /fb ~ ∼ 0 b → tW χ jets and missing energy SUS-13-008 SUS-13-013 L=19.5 /fb ~ ∼ 0 b → bZ χ s = 8 TeV SUS-13-008 L=19.5 /fb ∼ 0 ∼ ∼ 0 ∼ 0 χ χ ± → lll ν χ χ x = 0.05 EWK gauginos SUS-13-006 L=19.5 /fb x = 0.50 ∼ 2 ∼ ∼ ∼ x = 0.95 χ + χ - → l + - l ν ν χ 0 χ 0 SUS-13-006 L=19.5 /fb CMS Preliminary ∼ ± ∼ 0 ∼ 0 ∼ 0 χ χ → W Z χ χ SUS-13-006 L=19.5 /fb 2 ∼ ± ∼ 0 ∼ 0 ∼ 0 χ χ → H W χ χ SUS-13-017 L=19.5 /fb For decays with intermediate mass, • much less constrained: ∼ 0 ∼ 2 ± ∼ 0 ∼ 0 χ χ → ll τ ν χ χ SUS-13-006 L=19.5 /fb x = 0.05 x = 0.95 x = 0.50 m = x ⋅ m -(1-x) ⋅ m ∼ 0 ∼ 2 ± ∼ 0 ∼ 0 χ χ → τ τ τ ν χ χ intermediate mother lsp SUS-13-006 L=19.5 /fb 2 slepton ~ ∼ 0 l → l χ SUS-13-006 L=19.5 /fb 0 200 400 600 800 1000 1200 1400 *Observed limits, theory uncertainties not included Mass scales [GeV] ⋆ top squarks Only a selection of available mass limits Probe *up to* the quoted mass limit ⋆ purely electroweak particles Note specific assumptions: signature: simplified models, . . . three charged leptons After the discovery of a Higgs boson(-like) particle – a theorist’s perspective Heidi Rzehak February 21, 2014