1. QFTHEP-2011 24.09.2011 – 01.10.2011 A.Beylin, V.Beylin, A.Pivovarov SFU, MIPT Scenarios of Higgs bosons and Z’ manifestations in the minimal gauge extension of the SM

2. Outline An introduction Higss sector of the model Z’-boson H – Z’ combined effect in ttZ Conclusions 2

3. Beyond the SM: MSSM (two neutral Higgs bosons +…), B-L(two neutral Higgs bosons), LH (Higgs boson + extra vectorlike quark)… Specific manifestations in the structure of invariant distributions; Interference with the QCD leads to the “peak- and-dip” picture; A possibility to “switch off” some channels (weak coupling heavy Higgs with tt-pair in the MSSM for some tgβ, for example) Most simple model to study interference effects – the U(1) B-L gauge extension of the SM – a small number of parameters. 3

4. The U(1) SM extensions Early papers: R.N.Mohapatra, R.E.Marshak (1980); A.Masiero, J.Nieves, T.Yanagida(1982); R.N.Mohapatra, G.Senjanovic (1983) and others… More recent papers: S.Khalil (2006); W.Emam, S.Khalil (2007); W.Emam, P.Mine (2009); L.Basso, S.Moretti, G.M.Pruna, A.Belyaev, C.H.Shepherd- Themistocleus (2008 – 2011). Interference effects: K.Gaemers, F.Hoogeven (1984); D.Dicus, A.Stange, S.Willenbrock (1994); D.Berdine, N.Kauer, D.Rainwater (2007); R.Barcelo, M.Masip (2010). And many others. 4

5. The minimal gauge extension of the SM SU(3) C x SU(2) W x U(1) EM x U(1) B-L Known problems of the SM The extended model contains: extra gauge vector Z’ – boson from the B-L gauge symmetry extra (heavy) singlet Higgs boson three right-handed (heavy) neutrino the mixing and masses of neutrino, the problem of mass hierarchy, the Higgs boson(s) origin, the DM nature, baryon asymmetry. 5

6. There are two Higgs bosons, h 1,h 2 with masses Here λ 1, λ 2, λ 3, x, v - Yukawa constants and vacuum shifts for the Higgs fields 6

7. “Strong coupling” regime ≈≈ ≈ 3· α ≈ π/4 7 α- scalar’s mixing angle

8. h i ZZ’ interaction: Z’- extra gauge boson - ZZ’ mixing angle, it is ~ 1/1000 RG analysis and restrictions from LEP and LHC prefer M Z’ ~ O(TeV), M Z’ /g’≥7 TeV h i Z’Z’ interaction: The model contains heavy right neutrino with an interesting phenomenology See: W.Emam, S.Khalil, 2007; L.Basso e.a., 2009 8

9. pp h 1 h 2 ttZ via two Higgs bosons states, Z’ ttZ’* and ttZ* final states can be interesting 9

10. M h 1 =480 GeV, M h 2 =820 GeV, M Z’ =700 GeV, g’= 0.1 α = π/3 M h 1 =140 GeV, M h 2 =600 GeV, M Z’ =700 GeV, g’= 0.1 α = π/6 M h 1 =140 GeV, M h 2 =600 GeV, M Z’ =700 GeV, g’= 0.1 α = π/3 tt-pair squared mass distribution for different M h and α “light” Z’ case 10

11. M h 1 =140 GeV, M h 2 =600 GeV, M Z’ =3.5 TeV, g’= 0.5 α = π/4 M h 1 =480 GeV, M h 2 =820 GeV, M Z’ =3.5 TeV, g’= 0.5 α = π/6 M h 1 =480 GeV, M h 2 =820 GeV, M Z’ =3.5 TeV, g’= 0.5 α = π/4 tt-pair squared mass distribution for different M h and α “heavy” Z’ case 11

12. M h =270 GeV, α = π/6 M h =460 GeV, α = π/4 M h =270 GeV, α = π/3 tg β =1.5 12 The ratios of differential distributions in E b for the extended model with U(1) B-L and the MSSM in the H tbW decay

13. M h =270 GeV, α = π/4 tg β =30 13

14. Conclusions Interference effects in the models with two scalar states are important, especially if their masses are close (“strong coupling” regime in U(1) B-L ), their contributions for the process are significant depending on the parameters. Z’ peak is seen in the distributions, however its width and amplitude strongly depend on the model parameters (scalar masses, mixing angle, extra U(1) coupling g’, widths of scalars) Distributions for the Higgs boson decays in the models with two neutral scalars are similar and nearly coincides in H tbW (U(1) B-L and MSSM) for some values of the mixing angle and small tgβ. For high tgβ predictions differs substantially. Known “peak-and-dip” structure induced by interference is substantially eroded in the case with two scalars. 14

15. tt-pair squared mass distribution for different M h and α “heavy” Z’ case (smoothed) M h 1 =480 GeV, M h 2 =820 GeV, M Z’ =3.5 TeV, g’= 0.5 α = π/6 M h 1 =140 GeV, M h 2 =600 GeV, M Z’ =3.5 TeV, g’= 0.5 α = π/4 M h 1 =480 GeV, M h 2 =820 GeV, M Z’ =3.5 TeV, g’= 0.5 α = π/4 15