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Gauged Flavor

Gauged Flavor. R. N. Mohapatra GUT 2012, Kyoto, 2012. Two Fundamental puzzles of SM. ( i ) Origin of Mass : two problems : (a) quark masses : SM Higgs (b) neutrino masses; N ew Higgs, New symmetries Origin of Flavor :

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Gauged Flavor

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  1. Gauged Flavor R. N. Mohapatra GUT 2012, Kyoto, 2012

  2. Two Fundamental puzzles of SM (i) Origin of Mass:two problems: (a) quark masses : SM Higgs (b) neutrino masses; New Higgs, New symmetries Origin of Flavor: Fermion masses, mixings, CP and P, strong CP

  3. Understanding Flavor • Zero fermion masses SM + RH nu  flavor symmetry group: • Hope is that observed flavor structure is a consequence of breaking this symmetry- • Questions: a) Gauge or global symmetry ? b) Scale of the symmetry breaking? c) New dynamics of the symmetry ?

  4. Global Flavor symmetry • Continuous:Breakingleads to massless familons(Wilczek) • Must decouple before BBN- • Not seen in experiments so far- • Limits on the scale (PDG): from and decays: (Jodidio et al.; Atiya et al ) • Discrete :Domain wall problem; not favored by string theoriesunless gauged • (an argument in favor of gauged flavor)

  5. Gauged Flavor Symmetry • SM provides an excellent description of flavor violation. Accident or something fundamental ? • Minimal Flavor violation hypothesis:(Chivukula, Georgi; Buras et al; D’Ambrosio et al) -Any Flavor [U(3)]6 breaking effect is proportional to SM Yukawa type spurions: Yu ~(3, 3* , 1), etc. • Example of a theory where this happens: SUSY with universal scalar masses or GMSB etc. • Universal scalar masses

  6. Need for Flavor gauging • A natural speculation: the spurions are vevs of actual scalar fields: • If flavor symmetry is not gauge symmetry, there will be massless Goldstone bosons and are troublesome for cosmology. • How to implement this in a proper way and does it have any observable effect ?

  7. Naïve Gauged Flavor and gauged flavor scale • No extra fermionsAnomaly constraints restrict gaugeable symmetries tovector subgroups ; (needs RH neutrino for global anomaly freedom) • Scale of symmetry breaking set by FCNC : • imply  (for gH~1) (UTFIT coll. Bona et al)

  8. Typical structure of these theories: • Gauge group: • Sym Br. Higgs: SM H + (Y-flavon fields) • < > breaks flavor sym; H breaks SM; • Fermion masses arise from (typically) • Implies e.g. that: • .

  9. New approach: Use Quark seesaw: Add vector like quarks to SM ( ) and use seesaw like mass matrices:  In Left-Right models  # of parameters: for quarks only 24 in LR; 48 in SM (Davidson, Wali’87;… Babu and RNM’89,…..)

  10. Full Flavor Gauging Advantage of seesaw approach in SM: Full chiral flavor group can be anomaly free and can be gauged (Grinstein, Redi and Villadoro’09) Quark masses: Note inverted hierarchy for masses !! Flavor scale is same as vector like quark mass One flavor scale comes down to TeV range; New vector like quarks in the LHC range;

  11. Basic reason for lower scale • Inverse relation between quark and vector like masses  for Horizontal scale: Huge suppression Lower flavor gauge scale for higher flavors.

  12. A Conceptual problem • Gauge protection of fermion masses : “all fermion masses must arise from a gauge symmetry breaking- otherwise it could be of the order of Planck mass !!” e.g. in QED, electron mass is not gauge protected but in SM, it is. • In GRV model, pairs have same gauge quantum numbers and get arbitrary gauge unprotected mass. • No neutrino mass

  13. Flavor gauging with Left-Right Symmetry • Guadagnoli, Mohapatra , Sung, arXiv: 1103.4170 JHEP 04, 093 (2011) • LR allows more economical flavor gauging: From (SM) to (LR) All Fermion masses gauge protected-connected to weak, LR and flavor gauging scales !! (i) generates neutrino mass (ii) Solves strong CP problem from parity (iii) # of parameters: 10 for quarks: connected to symmetries • Two versions:TeV parity or no parity TeV SU(2)R

  14. Details of Model • Anomaly free Fermion and Higgs assignment:

  15. Some details: TeV parity • Quark sector: Fermions: • Higgs fields: LR doublets: Flavon fields: (EW singlets) • Yukawa couplings and fermion mass protection: • LY= • Flavor from sym br. • ; Vectorlike quarks

  16. Consequences: • Seesaw matrix: similarly for d • All flavor consequence of symmetry breaking; • Two new scales beyond SM • Right hand weak scale: vR , Flavor scales <Y>; • Quark seesaw  • Flavor gauge boson masses determined by quark mixings. • FCNC interactions given by~ • KL –KS imply Yu > 2000 TeV;  top partner ψ ~200 GeV for vR ~ TeV.

  17. FCNC Bounds on new physics: • Flavor gauge boson and vectorlike quark masses • TeV parity(orange): MVH>10 TeV; M > 5 TeV; otherwise (blue) much lower-both near a TeV.

  18. Special top sector • Predicts large top mixings with vector like quarks due lower Ytlarge FCNC (in progress) • RH top LH top

  19. LHC searches for vectorlike quarks • Production: ATLAS 1.04fb-1 : 3rd gen. partner MQ > 760 GeV. For TeV mass • CMS: pp->QQ-bart+Z+t-bar+Z MQ > 475 GeV

  20. Other consequences • Reduction of top width • probe Parameterize: SM prediction D0: <.018 Our model: intermediate top partner mediated graph 

  21. FCNC and other effects of Gauged Flavor • Possible anomaly can be resolved by new contributions; • and predictions are SM –like. (Buras, Carlucci, Merlo, Stamou’2011) • Full anomaly free gauge group can be extended to have chiral color; The model has axigluon, sometimes invoked to explain the 3-σ tt-bar asymmetry of CDF and D0 for Maxi ~ 500 GeV or so.

  22. Other Consequences • Non-unitarity of CKM matrix (Branco, Lavoura’86; Branco, Morozumi, Parada, Rebelo’94) • Effects small; < 1-2 % • Collider constraints and prospects: LHC , • Striking LHC signal 6b+2W

  23. Origin of flavor hierarchies •  :<YU,D> encode the flavor pattern. How to understand this ? • Step I: Higgs potential • For , minimum of VU is <Yu>= (a1, 0, 0); •  induces <Yd>=(b1,0,0) with b1 ~ a1 • Generates largest flavonvevs; smallest quark masses • Sym breaks :

  24. More flavor structure • Add new term to V: •  • Generates hierarchical masses: • Add Det Yu induces <Yu1 1 > ≠ 0; induces <Yd >

  25. Next order and mixings • More terms in the potential: • can generate the full mixing matrix e.g. • (Admittedly there is fine tuning !!)

  26. A Numerical analysis • Minimum of the potential:

  27. Loop alternative • Add new interaction of vectorlike quarks: sextet L+R [Y’= ] <Y’>≠ 0 • Generates hierarchical fermion masses and mixings

  28. Similarity to MFV hypothesis • All flavor structure resides in the scalar multiplets of GH :Yu,d . • All higher order flavor stucture therefore necessarily comes from them, as in MFV hypothesis.

  29. Solution to strong CP problem: • Seesaw Quark mass matrix: •  Arg Det M = 0 at tree level.  • One loop also maintain zero theta. New contribution at 2 loop. • No axion needed. • Planck scale corrections small for TeV scale parity unlike the axion solution. ( Babu, RNM’89)

  30. Estimating θ • 2-loop e.g. • (Babu, RNM’89)

  31. Lepton sector • Lepton sector similar • Neutrinos Dirac in the minimal model: • For , correct nu masses emerge- much less tuning than SM. Predicts Dirac nu as it is ! • For Dirac nu, WR bound goes up to 3.3 TeV from BBN. • LFV imply <Yν> ~103 TeV • Suspected symmetries could be subgroups of GH

  32. Implications for B-violation • Forbids D=6 proton decay operator; • Lowest allowed operator: QQψdRψdRQQ ΔB=2 N-N-bar oscillation • Also allows sphaleron operator: QQQQQQQQQLLL • If SU(3)Q =SU(3)l, allowed operator • Observation of p-decay can rule out model.

  33. Gauged Flavor with SUSY • Need for maintaining susy and sym breaking. • First problem D-terms can split squark masses enough to cause FCNC problems i.e. • However in GMSB framework, our Y does not get susy breaking mass till 3 loop; • OK.

  34. Change of Higgs mass bound • D-term causes increase in Mh over MSSM: +rad. corr. (An, Ji, RNM,Zhang’08)

  35. R-parity violation and p-decay problem • If model supersymmetrized, allows only R-P breaking terms of type: ψuc ψdcψdc • After sym breaking uR dRdR • Leads to neutron-anti-neutron oscillation: • Very similar to MFV models (Smith’09; Grossman et al’11) • Usual SUSY GUTs: Planck induced QQQL/MPl needs 10-7 suppression: No such problem in gauged F-models

  36. Possible Grand unification:SU(5)xSU(5) model (in progress) • Where do vector-like fermions come from? • Grand unification provides a justification: SU(5)xSU(5)x GHas an example + L R anomaly free ; non-chiral Examples: SU(3)H , SO(3)H

  37. Some Implications of unifying seesaw • Seesaw matrix from Lagrangian: SU(3) case • different from previous case. • (Koide’s talk) • Coupling unification possible and chiral color surviving down to TeV, with extra pair of left and right Higgs doublet. MU = 2.3x1013 GeV • Sin2 θW = Need to have different couplings for the two SU(5)’s at GUT scale !!

  38. Proton decay can explore light heavy mixings • No electroweak sym breaking proton is stable !! • Operator generated by GUT gauge boson exchange • OB= /MU 2 ; • Coupling unification different from usual MU =1013 GeV • EWSB mixes heavy vector like quarks with light quarks p-decay • Operator: • If vR /Mψ =10-3 , proton life time constraint ok. (For an alternative GUT approach: Feldmann (2011)) . .

  39. Conclusion • New approach to gauged flavor: FCNC allows flavor scale in TeV range (unlike simple gauged case); • Key to this: quark seesaw with new TeV mass vector-like fermionsrealization of MFV • LR version “protects all fermion masses”, solves strong CP problem and gives neutrino masses. • Flavor mixings and hierarchies out of flavor breaking- • Can be supersymmetrized. • Possibly grand unifiable (work in progress)!! • Unbroken subgroups can be used to predict mixings !

  40. LR scale INPUT for TeV parity case Low energy observables: combination of KL-KS, εK, d_n together.(uncertainty long distance effetcs); Parity defined as usual:( ) minimal model: (An,Ji,Zhang,RNM ’07) Parity as C (as in SUSY i.e. ) (Maezza, Nemesvek,Nemevsek,Senjanovic’10) A recent study by(Buras, Blanke,Gemmler, Heidesiek’11) Collider (CDF,D0) 640-750 GeV; CMS- 1.7 TeV Muon decay (TWIST) 592 GeV Broken TeV parity: weaker bounds on MWR No large tree level Higgs effect unlike canonical LR models.

  41. Bounds on New Physics from FCNC • Bounds on scale: • Is the dynamics of flavor then experimentally inaccessible ?

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