1. Durmu ş Ali Demir İ zmir Institute of Technology Reasons for … Results from … Extra U(1) in SUSY

2. What we have and what we add... +Higgs Boson ? Flavor Violation CP Violation

3. Z’ An extra Abelian symmetry U(1)’ atop SM gauge group. Diagonal of a non- Abelian gauge symmetry e.g. SU(2) R Extra dimensions (KK excitations of Z ) Resonances of TeV strings. Sources of Z’... Pick up this !

4. High-energy motivations for U(1)’… U(1)’ GUTs (extra U(1)s in E6 and SO(10) can survive down to EW scale.) Superstrings (string compactifications lead to several extra U(1)’s) Dynamical Symmetry Breaking (technicolor group involves a U(1)’ with flavour-violating couplings) Little Higgs Models (local subgroups of global symmetry involve U(1)’) Stuckelberg mechanism (that implements gauge- invariant massive vector bosons with a U(1)’ ) Pick up these two

5. Low-energy motivations for U(1)’... W MSSM =h e LH d E c + h u QH u U c + h d QH d D c + m H d H u Mass dimension = 0 Mass dimension = 1 A supersymmetric parameter not related to SUSY breaking theory obtains an exact U(1) invariance whose spontaneous breakdown leads to an unwanted Goldstone … the theory looses all its phenomenological relevance; the electroweak scale is destabilized… this is precisely what is needed … but how to stabilize this parameter to such a special scale?

6. For stabilizingto TeV scale workers have tried several ways: Extend Kahler potential by adding ; however, this solution rests on a Peccei-Quinn symmetry to forbid the same operator showing up in the superpotential. There is, however, tension with the astrophysical bounds on the axion scale. Replaceby a gauge-singlet chiral superfield whose VEV can generate an effective; however, theory possesses a discrete symmetry spontaneous breakdown of which generates serious tension with cosmology. Low energy motivation for U(1)’... Giudice-Masiero Mechanism NMSSM

7. Replace by a SM-singlet chiral superfield whose VEV can generate an effective Extend gauge structure by an additional Abelian factor The third way: Low energy motivation for U(1)’... U(1)’ Model

8. Low energy motivation for U(1)’... W m = h e LH d E c + h u QH u U c + h d QH d D c + h s S H d H u Mass dimension = 0 W m is the superpotential dictated by the m problem. A bare m term is forbidden by U(1)’ invariance: Q’ S + Q’ Hu + Q’ Hd = 0.

9. MSSM NMSSM U(1)’ Model This low-energy m problem solving model is general enough to cover several U(1)’ models of varying origin. Studying this model covers several special models. Low energy motivation for U(1)’...

10. An example: E6 motivated U(1)’... E6  SO(10) x U(1) y  SU(5)xU(1) c x U(1) y  G SM x U(1)’ U(1)’ = Cos( q) U(1) y - Sin( q) U(1) c Specific Models: q0-p/2ArcSin[a 1 ] ArcSin[a 2 ] U(1)’ U(1) y U(1) c U(1) h U(1) I a 1 = (3/8) 1/2 and a 2 = -(5/8) 1/2

11. Implications of U(1)’: Higgs Sector MSSM : m h << m H ~ m A NMSSM : m h << m H ~ m A << m H’ ~m A’ U(1)’ : m h << m H ~ m A << m H’ ~ M Z’ Number of Higgs’ Hierarchy of Higgs’ ModelCP = + CP = - MSSMhH--A NMSSMhHH’AA’ U(1)’hHH’A--

12. Implications of U(1)’: Higgs Sector Bounds on the Lightest Higgs Boson Mass: MSSM: NMSSM: U(1)’:

13. Implications of U(1)’: Little Hierarchy For m h > 114 GeV: MSSM: U(1)’: MSSM pushes SUSY breaking scale upwards to satisfy LEP bound on m h whereby generating the infamous little hierarchy problem (that gave rise to little Higgs models) !

14. Implications of U(1)’: CP Violation The Higgs sector admits no CP violation at tree level. As in the MSSM CP violating effects arise at the loop level. U(1)’ breaking generates | m| such that its phase is a loop-induced quantity. In this sense, phase of m is predicted to be small from the scratch. (This phase is required to be small by EDM bounds) m= | m | e i f Small since loop-induced Proportional to

15. Implications of U(1)’: Neutrino Masses Experiments have yet established if neutrinos are Dirac or Majorana. Tiny neutrino Dirac masses can be induced by U(1)’ breaking and are protected by U(1)’ itself. Introducing: W mn = W m + (Y n /M R ) S L.H u N with ~ 3 TeV and M R ~ M GUT the neutrino masses generated show excellent agreement with the oscillation data.

16. Implications of U(1)’: Baryogenesis Add more singlets to theory: W m n S = W m n + l S 1 S 2 S 3 Heavy Z’ is achieved with a light Higgs sector Introduces tree-level CP violation SM: Strongly first order EWPT for m h < 72 GeV, only. MSSM: Strongly first order EWPT only for a small parameter region. NMSSM: Strongly first order EWPT for a wide parameter region but with cosmological domain walls. U(1)’ (secluded): Strongly first order EWPT for a wide parameter region. tan b ~ 1 for consistency

17. Implications of U(1)’: Cold Dark Matter Lightest neutralino is a good candidate for CDM particle; WMAP bounds are satisfied in a wide parameter region. The lightest neutralino could be Singlino, Zino’ or Bino, each being characterized by different collider and astrophysical signatures. For most of the parameter space with heavy singlino Bino is the LSP. A right-handed sneutrino, if it is the lightest, can be good candidate for dark matter.

18. Implications of U(1)’:Implications of U(1)’: FCNC U(1)’ couplings are typically family-nonuniversal. 1 st and 2 nd generations are bounded to be universal by experiment; the 3 rd family is not. Z’ exchange influences certain 3  2 or 3  1 rare decays such as B  f K and B  p K (may be an alternative to flavoured soft masses in the MSSM).

19. Searching for U(1)’ invariance … 1) Searching through the Z’ boson… 2) Searching through the Zino’ fermion…

20. Search through Z’ … Bounds from CDF Run 2:

21. Search through Z’ … Search for Z’ will continue at the LHC, which will be able to observe Z’ bosons as heavy as 4 TeV.

22. Search for Z’ … Forward-Backward asymmetry at the Z’ pole is a sensitive probe of various models.

23. Search for Z’ … ILC vs. LHC discovery reach ….

24. MSSM U(1)’ Search through Zino’ … Squarks and gluinos are produced copiously at LHC. Their decays carry foot-prints of the U(1)’ invariance..

25. 1 jet + 0 lepton + MET MSSM: U(1)' : 1 jet + 0 lepton + MET 1 jet + 4 lepton + MET 1 jet + 2 lepton + MET Search through Zino’ … Even if Z’ is heavy, Zino’ can be light and U(1)’ can group can be hunted via the leptonic events at the LHC.

26. Purely hadronic events (jets + MET events) are lesser in U(1)’ model… Search through Zino’ …

28. Concluding … A Z’ boson can stem from several sources the most common of which being a U(1)’ symmetry augmenting G SM. U(1)’ models do have observable implications for various observables. U(1)’ gauge invariance can be discovered or can hinted in via either Z’–induced or Zino’—induced events!

29. Thank you !!