Common exotic LHC signatures from underlying models with a composite Higgs Thomas Flacke IBS CTPU, Daejeon based on: G. Cacciapaglia, H. Cai, A. Deandrea, TF, S.J. Lee, A. Parolini [JHEP 1511 (2015) 201] A. Belyaev, G. Cacciapaglia, H. Cai, G. Ferretti, TF, H. Serodio, A. Parolini [JHEP 1701 (2017) 094] G. Cacciapaglia, G. Ferretti,TF, H. Serodio [arXiv:1710.11142] N. Bizot, G. Cacciapaglia, TF [arXiv:1803.00021] HL/HE LHC Meeting, April 4th, 2018
Outline • Motivation & Overview H ? • Towards UV embeddings of a composite Higgs: Models • New light pseudo-Nambu Goldstone bosons and their ?? phenomenology • Top-partners and common exotic decays / new signatures • Conclusions 2/23
Motivation for a composite Higgs α s An alternative solution to the hierarchy problem: • Generate a scale Λ HC <<M pl through Running of the new a new confining gauge group. strong coupling H • Interpret the Higgs as a pseudo-Nambu- Goldstone boson (pNGB) of a spontaneously ( 𝜔𝜔 ) 10 19 GeV broken global symmetry of the new strong sector. eV Kaplan, Georgi [1984] f m h M pl Λ HC =g * f ~few TV The price to pay: eV • From the generic setup, one expects additional resonances (vectors, vector-like fermions, scalars) around Λ HC (and additional light pNGBs?). ρ , ρ µ O(few TeV) • The non-linear realization of the Higgs yields T’ deviations of the Higgs couplings from their SM values. f > 800 GeV 𝝆 ’? • … many model-building questions … • … and potentially new signatures for LHC … “Higgs” 125 GeV a’?? 3/23
Composite Higgs Models: Towards an underlying model and its low-energy phenomenology Ferretti etal. [JHEP 1403, 077] classified candidate models which: c.f. also Gherghetta etal (2014), Vecchi (2015), Ferretti (2016) for related works on individual models • contain no elementary scalars (to not re-introduce a hierarchy problem), • have a simple hyper-color group, • have a Higgs candidate amongst the pNGBs of the bound states, • have a top-partner amongst its bound states (for top mass via partial compositeness), • satisfy further “standard” consistency conditions (asymptotic freedom, no anomalies) 4/23
Example: SU(4)/Sp(4) coset based on GHC = Sp(2Nc) and colored pNGBs Field content of the microscopic fundamental theory and its charges w.r.t. the gauge group Sp(2N) × SU(3) × SU(2) × U(1) , and the global symmetries SU(4) × SU(6) × U(1) : Sp ( 2 N c ) SU ( 3 ) c SU ( 2 ) L U ( 1 ) Y SU(4) SU(6) U(1) ψ 1 1 2 0 ψ 2 4 1 − 3 ( N c − 1 ) q χ 1 1 1 / 2 ψ 3 − 1 / 2 1 1 ψ 4 χ 1 2 / 3 χ 2 3 1 χ 3 q χ 1 6 χ 4 3 1 − 2 / 3 χ 5 χ 6 [ JHEP1511,201 ] 5/23
Bound states of the model: Bound states of the model: spin SU(4) × SU(6) Sp(4) × SO(6) names contains SU(2) L × SU(2) R 0 ( 6 , 1 ) ( 1 , 1 ) ψψ σ bidoublet “H” ( 5 , 1 ) π ( 1 , 21 ) ( 1 , 1 ) 0 χχ σ c ( 1 , 20 ) π c form a and 𝜃 ’; SM singlets ψ 1 ( 6 , 6 ) ( 1 , 6 ) 1/2 χψψ 1 ψ 5 ( 5 , 6 ) 1 ψ 1 20 colored pNGB: ( 6 , 6 ) ( 1 , 6 ) 1/2 χψψ 2 ψ 5 ( 5 , 6 ) (8,1,1) 0 ⊕ (6,1,1) 4/3 ⊕ (6,1,1) -4/3 2 1/2 ( 1 , 6 ) ( 1 , 6 ) ψχψ ψ 3 ψ 5 1/2 ( 15 , 6 ) ( 5 , 6 ) ψχψ 4 contain (3,2,2) 2/3 ψ 10 ( 10 , 6 ) 4 fermions: t L -partners ψσ µ ψ 1 ( 15 , 1 ) ( 5 , 1 ) a ( 10 , 1 ) ρ χσ µ χ 1 ( 1 , 35 ) ( 1 , 20 ) a c contain (3,1,X) 2/3 ( 1 , 15 ) ρ c [ JHEP1511,201 ] fermions: t R -partners This is the BSM + Higgs sector which interacts with SM gauge bosons and matter through: SM gauge interactions, (global) anomaly couplings, and mixing of the top with top partners, 6/23
Full list of "minimal" CHM UV embeddings [ JHEP1701,094 ] 7/23
New PNGBs and their phenomenology Additional model-dependent pNGBs (colored, EW charged, and neutral): [ JHEP1701,094 ] Additional two pseudo scalars associated to SSB of U(1) 𝜓 ⨉ U(1) 𝜔 In ALL models: • One linear combination has a G HC anomaly ( η ’, no pNGB) • One linear combination is G HC anomaly free ( a, remaining pNGB) 8/23
The timid pNGB summary and phenomenology a and η ’ : Arise from the SSB of U(1) 𝜓 ⨉ U(1) 𝜔 . One linear combination has a G HC anomaly ( η ’ ) and is expected heavier. The orthogonal linear combination ( a ) is a pNGB. L = 1 2( ∂ µ a )( ∂ µ a ) − 1 iC f m f a ¯ X 2 m 2 a a 2 − ψ f γ 5 ψ f (1) f a f + g 2 G aµ ν + g 2 K W a W iµ ν + g 0 2 K B a s K g a µ ν ˜ µ ν ˜ B µ ν ˜ G a W i B µ ν 16 π 2 f a 16 π 2 f a 16 π 2 f a • The mass m a must result from explicit breaking of the U(1) symmetries → treated as free parameter in the effective theory. • f a results from chiral symmetry breaking. . • The WZW coefficients 𝜆 i are fully determined by the quantum numbers of 𝜓 , 𝜔 . • Effective couplings of a to the Higgs are induced at loop level : L haa = 3 C 2 t m 2 a v log Λ 2 t κ t h ( ∂ µ a )( ∂ µ a ) , m 2 8 π 2 f 2 t L hZa = 3 C t m 2 2 π 2 f a v ( κ t − κ V ) log Λ 2 t g A h ( ∂ µ a ) Z µ , m 2 t 9/23
Coefficients of a for sample models M1 - M12 C t: [ arXiv:1710.11142 ] [ arXiv:1710.11142 ] 10/23
TCP Phenomenology • a is produced in gluon fusion (controlled by K g /f a ). • Assoc. production with a Z is tiny ➝ No bounds from LEP Higgs searches. • a decays to gg, WW, ZZ, Z 𝛿 , 𝛿𝛿 , ff with fully determined branching ratios. • For heavier a, LHC di-boson searches apply [JHEP 1701, 094] . • For light a (translating existing bounds and searches): For a given model, we can combine bounds on all channels to get a bound on f a . E.g.: M8. 11/23 [ arXiv:1803.00021 ]
TCP Phenomenology NOTE: Low mass region has a “gap” between 15 - 65 GeV. 𝛿𝛿 [PRL113, 17801] (ATLAS) [CMS-PAS-HIG-17-013] BR(h ➝ BSM)<.34 [JHEP1608, 045] (ATLAS+CMS) 𝜈𝜈 [ arXiv:1710.11142 ] [PRL109, 121801] (CMS) [ATLAS-CONF-2011-020] 12/23
How can we search the gap at low mass? 𝜐𝜐 ! The gluon-fusion production cross section for light a is large… … and the 𝜐𝜐 branching ratio is (for most models) not small. [ arXiv:1710.11142 ] Soft 𝜐 lep or 𝜐 had cannot be used to trigger, but ISR can boost the gg ➝ a ➝ 𝜐𝜐 system (at the cost of production cross section, but we have enough). [ arXiv:1710.11142 ] 13/23
How can we search the gap at low mass? 𝜐𝜐 ! As a very naive proof of principle analysis we look for a j 𝜐 𝜈 𝜐 e final state (jet + opposite sign, opposite flavor leptons) with cuts: • p T 𝜈 > 42 GeV (for triggering) • p Te > 10 GeV [ arXiv:1710.11142 ] • m 𝜈 e < 100 GeV • Δ R 𝜈 j > 0.5, Δ R ej > 0.5, • Δ R 𝜈 e < 1.0 [ arXiv:1710.11142 ] 13 TeV, 300 fb expected bounds (S/ √ B = 3) 14/23
How can we search the gap at low mass? 𝜐𝜐 ! This first proof of principle study is not optimized. • Cutting harder on Δ R 𝜈 e can substantially increase background suppression for the lighter mass range. • We did not use any 𝜐 ID or triggers. [ arXiv:1710.11142 ] • We only used the OSOF lepton channel. 𝜐 𝜈 𝜐 𝜈 , 𝜐 𝜈 𝜐 had , 𝜐 had 𝜐 had have larger branching ratios but require a more careful background analysis. [And needs tagging efficiencies for boosted 𝜐 𝜈 𝜐 had , 𝜐 had 𝜐 had systems which are beyond our capabilities, but possible for experimentalists.] 15/23
Implications for VLQ searches Current VLQ searches focus on charge 5/3, 2/3, -1/3, -4/3 top partners which are pair (or single) produced and decay into t/b and h/W/Z. If pNGBs beyond the Higgs are present in the model they are conceivably lighter than top partners. How large are top partner decay rates into pNGBs other than the Higgs? The top obtains its mass through mixing with a top partner. But the top partners come a full multiplets of the global symmetry groups and the Higgs comes in the Goldstone-boson matrix which includes ALL pNGBs of the model. Thus, we can relate the coupling of a top partner to the Higgs to its couplings to other pNGBs in underlying models. Scanning through the different underlying models we looked for “common exotic” top partner decays and found: 16/23
Common exotic VLQ decays Candidate 1 : decays to the singlet pseudo-scalar a Effective Lagrangian(s): ✓ g g W + P L b + κ T κ T � i / � 2 T / T / L T = T D − M T T + ZP L t √ W,L Z,L 2 c W ◆ M T − κ T ThP L t + i κ T a,L TaP L t + L ↔ R + h.c. , h,L − v ✓ g g Z + P L b κ B W − P L t + κ B � i / � 2 B / B / L B = B D − M B B + √ W,L Z,L 2 c W ◆ M B − κ B BhP L b + i κ B a,L BaP L b + L ↔ R + h.c. . h,L v Benchmark parameters (obtained as eff. parameters from UV model): κ T κ T κ T κ T Bm1 : M T = 1 TeV , Z , R = − 0 . 03 , h , R = 0 . 06 , a , R = − 0 . 24 , a , L = − 0 . 07 ; κ B κ B κ B Bm2 : M B = 1 . 38 TeV , W , L = 0 . 02 , W , R = − 0 . 08 , a , L = − 0 . 25 , (2.3) 17/23
Common exotic VLQ decays • T and B can be produced like “standard” top partners: QCD pair production or single production. • New final states: MANY, depending on m a and single- or pair- production (E.g. heavy a and pair production: “p p > T T~, T > t a, a > t t~”; that’s a 6 top final state) 18/23 [ arXiv:1803.00021 ]
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