Higgs mediated lepton flavour violation, A Celis

talk at XLII International Meeting on Fundamental Physics
http://benasque.org/2014imfp/

Transcript

1. Higgs mediated lepton flavour violation IFIC, Universitat de Valencia-CSIC 29-02-2014 Alejandro Celis (e-mail) XLII International Meeting on Fundamental Physics Benasque, Spain
2. A. Celis. (29-02-2014) Contents Motivation to study Higgs mediated LFV Low energy constraints Recent progress on decays AC, Cirigliano, Passemar (1309.3564) J. T. Daub et al. (1212.4408) Higgs mediated LFV Prospects for LFV Higgs decays at the LHC Improving the Hadron Physics of Non-Standard-Model Decays: Example Bounds on R-parity Violation Lepton flavor violation in the Higgs sector and the role of hadronic tau-lepton decays
3. Charged weak current is non-diagonal in the fermion mass basis Neutral weak current is diagonal in the fermion mass basis. CKM matrix Diagonalizing the mass terms after EWSB The Higgs boson couplings are not dictated by gauge symmetries. A. Celis. (29-02-2014) Higgs mediated LFV
4. In the absence of Yukawa couplings the SM has a global flavour symmetry rotations of The lepton sector posses a similar flavour symmetry, but in this case it depends on how neutrino masses are implemented rotations of Minimal field content Cirigliano et al. (0507001) With the discovery of the 126 GeV Higgs boson, we can now access directly the flavour symmetry breaking sources (Yukawa couplings) A. Celis. (29-02-2014) Higgs mediated LFV
5. Many scenarios of physics beyond the SM predict rates for charged lepton flavour violating transitions at observable levels for a long review see: M. Raidal et al. (0801.1826) Different channels to probe charged LFV at low energy Important to unravel the origin of LFV conversion in nuclei Flavour violation in the Higgs sector A. Celis. (29-02-2014) Higgs mediated LFV
6. So far, what do we now about the Yukawa couplings of the 126 GeV Higgs? LHC data confirms that the relation hold for 3º family fermions (with still significant uncertainties) Ellis, You (1303.3879) Not much can be done for 1º and 2º family fermions at the LHC. High Lum. LHC can probably measure Flavour violation in the Higgs sector Coupling with vector bosons also SM-like A. Celis. (29-02-2014) Higgs mediated LFV
7. Indirect bonds on flavour changing couplings of the 126 GeV Higgs are already quite strong in most of the cases, putting the relevant decay rates beyond the reach of colliders In the quark sector h ¯ d b ¯ b d Y ∗ bd PL + Ydb PR Y ∗ bd PL + Ydb PR t h h ¯ u c Y ∗ ct PL + Ytc PR Y ∗ tu PL + Yut PR Y Y (a) (b) Flavour violation in the Higgs sector Isidori, Nir, Perez (1002.0900) M. Bona et al. (0707.0636) Harnik, Kopp, Zupan (1209.1397) A. Celis. (29-02-2014) Higgs mediated LFV Blankenburg, Ellis, Isidori (1202.5704) Harnik, Kopp, Zupan (1209.1397) from CMS multi-lepton search flavour changing Higgs couplings with top are weakly constrained
8. Flavour violation in the Higgs sector fixing the diagonal couplings to their SM value In the lepton sector Blankenburg, Ellis, Isidori (1202.5704) Harnik, Kopp, Zupan (1209.1397) h τ µ µ µ Y ∗ τµ PL + Yµτ PR Y ∗ µµ PL + Yµµ PR + γ τ µ µ µ Y ∗ µµ PL + Yµµ PR h N µ N e Y ∗ µe PL + Yeµ PR + µ h µ γ N µ N e Y ∗ µµ PL + Yµµ PR Y ∗ µe PL + Yeµ PR + e h e γ N µ N e Y ∗ µe PL + Yeµ PR Y ∗ ee PL + Yee PR τ h τ τ γ µ Y ∗ ττ PL + Yττ PR Y ∗ τµ PL + Yµτ PR + µ h µ τ γ µ Y ∗ τµ PL + Yµτ PR Y ∗ µµ PL + Yµµ PR Diaz-Cruz, Toscano (9910233) Indirect bounds are very weak for tau-mu and tau-e A. Celis. (29-02-2014) Higgs mediated LFV conversion in nuclei
9. µ h γ, Z t t τ γ µ µ h γ, Z W W τ γ µ µ h γ, Z W W τ γ µ µ h µ Z µ τ γ µ diagrams extracted from Harnik, Kopp, Zupan (2012) LFV radiative decays A transition dipole moment is generated at the loop level Dominant contribution from 2-loop diagrams of Barr-Zee type Chang, Hou, Keung (1993) 1-loop diagram involve three chirality flips This is just an accident at the 1-loop level and can be avoided at higher orders Bjorken, Weinberg (1977) τ h τ τ γ µ Y ∗ ττ PL + Yττ PR Y ∗ τµ PL + Yµτ PR + µ h µ τ γ µ Y ∗ τµ PL + Yµτ PR Y ∗ µµ PL + Yµµ PR
10. LFV leptonic decays h τ µ µ µ Y ∗ τµ PL + Yµτ PR Y ∗ µµ PL + Yµµ PR + γ τ µ µ µ Y ∗ µµ PL + Yµµ PR diagrams extracted from Harnik, Kopp, Zupan (2012) subdominant suppressed by small Yukawa additional suppression in the decay rate compared with the radiative mode Dassinger, Feldmann, Mannel, Turczyk (0707.0988) If LFV leptonic decays are observed at some point, a Dalitz plot analysis would provide a useful handle to disentangle different kinds of new physics
11. mu-e conversion in nuclei h N µ N e Y ∗ µe PL + Yeµ PR + µ h µ γ N µ N e Y ∗ µµ PL + Yµµ PR Y ∗ µe PL + Yeµ PR + e h e γ N µ N e Y ∗ µe PL + Yeµ PR Y ∗ ee PL + Yee PR plots from Harnik, Kopp, Zupan (2012) only Higgs coupling to up and down quarks relevant? Where does the nucleon mass comes from? A. Celis. (29-02-2014) Higgs mediated LFV By comparing different target nuclei one can disentangle different effective operators Kuno, Okada, (9909265) Kitano, Koike, Okada (0203110) Cirigliano, Kitano, Okada, Tuzon (0904.0957)
12. mu-e conversion in nuclei (at zero momentum transfer) Q=c,b,t from triangle anomaly trace of the energy-momentum tensor
13. A long-standing problem, how large is the strange quark content in the nucleon? R. D. Young, 1301.1765 from a recent review with state of the art Lattice calculations
14. Important points: - Need to consider the Higgs coupling with strange quarks and the effective Higgs-gluon interaction induced by heavy quarks - Need a proper description of the hadronic matrix elements up to invariant masses of the pion pair of ~1GeV These two points were not being addressed in the literature !! AC, Cirigliano, Passemar (1309.3564) First consideration of these points for Higgs mediated decays Interestingly, the problem was solved years ago in the context of very light Higgs decays Donoghue, Gasser, Leutwyler (1990) Recent progress on decays J. T. Daub et al. (1212.4408)
15. 0 0.5 1 1.5 2 2.5 3 s [GeV2 ] 0.01 0.1 1 10 |F V (s)|2 Fit result Belle data Photon mediated contributions require the pion vector form factor AC, Cirigliano, Passemar (1309.3564) Guerrero, Pich ´98, Pich, Portolés ´08, Gomez, Roig ´13. Dispersive parametrization following the properties of analyticity and unitarity of the FF Determined from a fit to the Belle data Theoretically: decay very well described by resonances
16. extracted from Donoghue, Gasser, Leutwyler (1990) Voloshin (1985) Using leading-order chiral perturbation theory very far from the naive expectation Using the triple constraints of chiral symmetry, analyticity, and unitarity, together with exp. input pi-pi scattering, etc Voloshin (1985) The other hadronic matrix elements were determined in previous works about
17. AC, Cirigliano, Passemar (1309.3564) Previous studies have been considering only (LO-ChPT) Equivalent to the naive estimate Impact of hadronic matrix elements on
18. Davidson, Verdier (1211.1248) LHC would provide stronger constraints, even with present data Harnik, Kopp, Zupan (1209.1397) Estimated sensitivity of the LHC with 20 fb^- of data Davidson, Verdier (1211.1248)
19. PDG 201X h(126) properties Decay Modes ... Confidence Level
20. Recent progress on decays AC, Cirigliano, Passemar (1309.3564) J. T. Daub et al. (1212.4408) Summary of main points discussed rely on techniques developed for the problem of calculating the decay width of a ~1 GeV Higgs into two pions, hot topic back in the late 80´s and 90´s Direct search for decays at the LHC can probe flavour violating Higgs couplings beyond the limits set by LFV tau decays Higgs interaction with nucleons and where does the nucleon mass comes from?
21. Richard Thompson Back-up
22. Possible to isolate CP-even and CP-odd Higgs exchange in semileptonic decays LFV semileptonic tau decays ----- even odd Precise knowledge of hadronic states involved provides important information (neglecting Z penguins)
23. From S. Mihara
24. following DGL
25. (Okubo-Zweig-Iizuka) Violation of the OZI rule Higgs to two pions proceeds mostly through the Higgs-gluon coupling and the Higgs-strange quark coupling. but pions have u,d valence quarks ¿?