1 / 38

Miguel-Angel Sanchis-Lozano

Searching for a light Higgs boson in Upsilon radiative decays. Subtitle : It’s now or never. email: mas@ific.uv.es. Miguel-Angel Sanchis-Lozano. Department of Theoretical Physics & IFIC University of Valencia – CSIC Spain. Two-Higgs Doublet Model (II). Higgs sector. MSSM.

bmclaren
Download Presentation

Miguel-Angel Sanchis-Lozano

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Searching for a light Higgs boson in Upsilon radiative decays Subtitle: It’s now or never email: mas@ific.uv.es Miguel-Angel Sanchis-Lozano Department of Theoretical Physics & IFIC University of Valencia – CSIC Spain Miguel-Angel Sanchis-Lozano IFIC-Valencia

  2. Two-Higgs Doublet Model (II) Higgs sector MSSM Physical Higgs bosons: (five) 1 neutral CP-odd Higgs bosons (A0) 2 neutral CP-even Higgs bosons (h0 H0) 2 charged Higgs bosons (H±) Coupling of fermions and the CP-odd Higgs A0 In a 2HDM of type II Enhancement Suppresion if tanβ > 1 tanβ stands for the 2 Higgs VEVs ratio < Hu >/< Hd > A large value of tanβ implies a largeA0 coupling to the bottom quark but a smallcoupling (i.e. small cot β) to the charm quark. Therefore, in the quest for NP effects we will focus on bottomonium decays and spectroscopy but not on charmonium: Miguel-Angel Sanchis-Lozano IFIC-Valencia

  3. Next-to-Minimal-Supersymmetric Standard Model (NMSSM) Physical Higgs bosons: (seven) 2 neutral CP-odd Higgs bosons (A1,2) 3 neutral CP-even Higgs bosons (H1,2,3) 2 charged Higgs bosons (H±) New gauge-singlet superfield Higgs sector Six “free” parameters vs three in the MSSM : κλ Aκ Aλμefftan β Singlet component Non-singlet component PQ symmetry or U(1)R slightly broken light pseudoscalar Higgs tan β = vu / vd A1 coupling to down type fermions Light dark matter? The A1 would be the lightest Higgs: NMSSM candidate compatible with present bounds: Light neutralino with a singlet component Gunion, Hooper, McElrath [hep-ph:0509024] McElrath [hep-ph/0506151], [arXiv:0712.0016] Miguel-Angel Sanchis-Lozano IFIC-Valencia

  4. Light neutral Higgs scenarios Susy scale ~ O(100) GeV-O(1) TeV sets the expected Higgs mass Well-known example: The photon is massless while W+, W- & Z0 are quite heavy! Gauge symmetry explains such a mass difference Protective symmetry? Light Higgs ! A possible (and promising) scenario in the NMSSM mA1 < mH1< mA2≈ mH1≈mH2≈ mH+= mH- ~10 GeV L & H ~100 GeV SM-like Light and heavy Higgs bosons can live together ~300 GeV almost degenerate Miguel-Angel Sanchis-Lozano IFIC-Valencia

  5. Peccei-Quinn & R-symmetries Solves the “-problem” If к =0 → U(1) Peccei-Quinn symmetry Spontaneous breaking  NGB (massless), an “axion” (+QCD anomaly): ruled out experimentally If the PQ symmetry is not exact but explicitly broken  provides a mass to the (pseudo) NGB leading to a light CP-odd scalar for small к IfAλand A = 0→ U(1)R symmetry; but if U(1)R is slightly broken →light pseudoscalar Higgs too Miguel-Angel Sanchis-Lozano IFIC-Valencia

  6. CPV MSSM At one-loop level, MSSM with complex parameters is not CP conserving The three Higgs neutral bosons mix together and the resulting three physical mass eigenstates: H1, H2 and H3 ( MH1 < MH2 < MH3 ) have mixed parities Higgs couplings to the Z boson would vary: The H1ZZ coupling can be significantly suppressed raising the possibility of a relatively light H1 boson having evaded detection at LEP[hep-ph/0211467] Miguel-Angel Sanchis-Lozano IFIC-Valencia

  7. Light Higgs windows at LEP (CPV MSSM) hep-ex/0406057 hep-ex/0406057 Diagram illustrating the effective coupling of a Higgs mass eigenstate H1 to the Z. Only the CP-even admixture h and H couple to Z while the CP-odd A does not: hence the H1ZZ coupling is reduced wrt a CPC scenario. hep-ex/0406057 CPX MSSM 95% exclusion areas using scans with different values of arg (At,b).The region excluded by Yukawa searches, Z-width constraints or decay independent searches is shown in red CPX MSSM 95% exclusion areas using scans with different values of the top mass Miguel-Angel Sanchis-Lozano IFIC-Valencia

  8. What about the NMSSM? Less constrained by LEP data and B-physics observables than the MSSM (depending on the singlet component fraction) Higgs mass values allowed down to several GeV Dermisek & Gunion, hep-ph/0510322 (LEP limits and low-fine-tuning) Hiller, hep-ph/0404220 Domingo & Ellwanger, arXiv:0710.3714 B physics Similarly for Little Higgs models with an extended structure of global U(1) symmetries broken both spontaneously and explicitly, possibly leading to light pseudoscalar particles in the Higgs spectrum Kraml et al. hep-ph/0608079 Miguel-Angel Sanchis-Lozano IFIC-Valencia

  9. Evading LEP limits from Z h0 final-state events(where the h0 decays into b’s) • Interpretation: e+ e- Z h0 Mass of a SM-like Higgs H1 (h0) lower than 114 GeV is allowed provided that mA1 < 2mb • Explains the Higgs-likeevent excess found at mh0~100 GeV Low-fine-tuning required, Dermisek & Gunion arXiv:0705.4387 SM Higgs with < 114 GeV decaying primarily to b’s ruled out A10A10 (BF ~ 90 %) Can be dominant if 2mτ< mA1 < 2mb τ+τ- τ+τ- b b Miguel-Angel Sanchis-Lozano IFIC-Valencia

  10. Our Proposal * Test of Lepton Universality in (1S,2S,3S) decays to (below) the few percent level @ a (Super) B factory Lepton universality in the SM: Gauge bosons couple to all lepton species with equal strength *M.A.S.L. hep-ph/0610042 Miguel-Angel Sanchis-Lozano IFIC-Valencia

  11. Leptonic width of  resonances Lowest Feynman diagram • Γll (as presented in the PDG tables) is an inclusive quantity:   l+ l- is accompanied byaninfinite number of soft photons The test of lepton universality can be seen as complementary to searches for a (monochromatic) photon in the  γττ channel • To order α3:Γll = Γll0 [ 1+δvac+ δvertex ]  Γll0 [ 1+δvac ] • Divergencies/singularities free at any order: Bloch and Nordsieck theorem & Kinoshita-Sirlin-Lee-Nauenberg theorem Warning! 3α /4π~ 0.17% 7.6% Contribution potentially dangerous for testing lepton universality if final-state radiation is not properly taken into account in the MC to obtain the detection efficiency in the analysis of experimental data Albert et al. Nucl. Phys. B 166 (1980) 460 δvac=δee+δ+δ+ δquarks Miguel-Angel Sanchis-Lozano IFIC-Valencia

  12. Testing Lepton Universality * From PDG ‘07 Lepton Universality in Upsilon decays implies <R/l > = 0 Miguel-Angel Sanchis-Lozano IFIC-Valencia

  13. LU A0 Lepton Universality Breaking? R/e(1S) R/(1S) R/e(2S) R/(2S) R/e(3S) R/(3S) 0.0 0.1 0.2 0.3 0.4 -0.1 0.0 R/l Miguel-Angel Sanchis-Lozano IFIC-Valencia

  14. Our conjecture to interpret an apparent Lepton Universality breakdown: photon unseen* nS  A0(l +l-) n, n’ = 1,2,3 nS  b(*)(n’S) [ A0*l +l- ] Tree-level NP process theoretically very simple! Key ideas: Experimental Such NP contribution would beunwittinglyascribed to the leptonic branching fraction (photon undetected*). Actually only for the tauonic decay mode. Prior M1 transition -   Theoretical A0 + b intermediate state or bb continuum A leptonic mass dependence of the decay width from the A0 coupling to fermions would break lepton universality. Contributions from SM processes (like Z0 – exchange) should be negligible. Notice that a light non-standard Higgs boson has not been excluded by LEP direct searches for a broad range of model parameters in different scenarios Prejudice against a light Higgs? *the photon can be looked for but might be not monochromatic if the intermediate state is broad Miguel-Angel Sanchis-Lozano IFIC-Valencia

  15. Mixing formalism**Drees and Hikasa, Franzini and Gilman, Fullana and M.A.S.L. [hep-ph/0702190] • radiative decays into leptons Miguel-Angel Sanchis-Lozano IFIC-Valencia

  16. Mixing of a pseudoscalar Higgs A0 and a b resonance e+ e-     τ+ τ- A00 , b0 unmixed states A0 , b mixed (physical) states 0 The ηb decays to leptons because of its mixing with the CP-odd Higgs 0 Smaller coupling strength than in the MSSM but still can be larger than in the SM If Xd > 1 Xd = cosA tanβ Miguel-Angel Sanchis-Lozano IFIC-Valencia

  17. Resonant and non-resonant decays QCD+binding energy effects small for a pseudoscalar A0 Polchinski, Sharpe and Barnes Pantaleone, Peskin and Tye Nason Leading-order Wilczek formula Mixing effect • Non-resonant decay • Resonant decay Mixing effect In the limit of small mixing, one recovers the leading-order perturbative expression M1 transition probability Miguel-Angel Sanchis-Lozano IFIC-Valencia

  18. Small mixing-angle limit small Perturbative calculation M.A.S.L. hep-ph/0307313 dividing by Bll Agreement! as it should Mixing calculation Miguel-Angel Sanchis-Lozano IFIC-Valencia

  19. Expected LUbreaking Green line: non-resonant decay Black line: resonant decay Red line: sum Xd=10, b0 = 5 MeV Miguel-Angel Sanchis-Lozano IFIC-Valencia

  20. Possible spectroscopic consequences b / A0 mixing Xd = cosA tanβ Xd =10,20,40 Xd = 10 broader b ? bmass shift ? due to the new physics contribution Hyperfine splitting m-mb unexpectedly large/or small b > [b2g] Miguel-Angel Sanchis-Lozano IFIC-Valencia

  21. Searches of b states for over more than 30 years No signal found so far! “Is there any point to which you would wish to draw my attention?” “To the curious incident of the dog in the night-time” “The dog did nothing in the night-time” “That was the curious incident”, remarked Sherlock Holmes from “Silver Blaze” by Sir A.C.D. Mixing b resonance / A0 Higgs boson Enfant terrible Petit bourgeois Miguel-Angel Sanchis-Lozano IFIC-Valencia

  22. A close look at a region of NMSSM parameter spacefocusing onallowed light Higgs bosons withnon-negligible couplings to down-type fermionsbut evading all experimental bounds Miguel-Angel Sanchis-Lozano IFIC-Valencia

  23. Xd =10 Xd > 5`` Xd κ λ Aλ= -200 GeV Aκ = -15 GeV μ = 150 GeV tan β= 40 Aλ~ - Κμ / λ Κ - (4/3) λ=0 0.1 ≤| cos A |≤0.5 tanβ~ 1/ [Aλ+Κμ / λ ] Ananthanarayan & Pandita, hep-ph/9601372 Xd = cosA tanβ Miguel-Angel Sanchis-Lozano IFIC-Valencia

  24. MA2= 300 GeV Xd = 10 Aλ= -220 GeV Aκ = -25 GeV μ = 200 GeV tan β = 20 MA1= 9 GeV MH1=98 GeV Xd > 5 Xd = cosA tanβ No Lep/B-physics constraints imposed Miguel-Angel Sanchis-Lozano IFIC-Valencia

  25. “Avvocato del diavolo” Devil’s Advocate Present experimental bounds for a light (~ 10 GeV)non-standard Higgs boson* coming fromLEP(e.g. final state Z0 +4b)B physics(e.g. Bsμ+ μ-)Cosmology(e.g. dark matter relic abundance) If there exists such a light Higgs boson... why it has not been observed yet? *Quite common prejudice: light Higgses were ruled out by LEP (only true in the CPC MSSM) Miguel-Angel Sanchis-Lozano IFIC-Valencia

  26. Plot of MA1 & Xd versus tanβusing NMHDECAY scan* All LEP and B physics constraints satisfied MA1<10.58 GeV MA1 *Special thanks to U.Ellwanger *Special thanks to U.Ellwanger Miguel-Angel Sanchis-Lozano IFIC-Valencia

  27. Bs μ+μ- cos 2 θA in the NMSSM • Current limit BF [Bs μ+μ-] < 5.8 10-8 • BF [Bs μ+μ-] ~ (μAt /mt)2 tan6β / MA4 ~ At=350 GeV At=350 GeV BF[Bs] Xd MA1 (GeV) tan β MA1 Miguel-Angel Sanchis-Lozano IFIC-Valencia

  28. In several NMSSM parameter regions (mainly at moderate λAλand smallκAκ) it may happen at the same time: • Large tanβ(for Aλ+ κs ≈ 0) • 0.1 ≤ | cos A | ≤ 0.5 (A0 mainly singlet but not completely) • |Xd| = 5 – 25 for tanβ = 10-40 • Low mass (e.g. 10 GeV) of the lightest CP-odd Higgs boson A1 • MA ~ 300 GeV (not too large mass of the next CP-odd Higgs A2) • Low fine-tunning in order to get a SM-like Higgs of mass about 100 GeV decaying into two pseudoscalars, thereby explaining the Z+b-jets event excess at LEP (Dermisek & Gunion, hep-ph/0510322) Fine tuning or suggestive coincidences ! Miguel-Angel Sanchis-Lozano IFIC-Valencia

  29. Conclusions I What if... there exists a light Higgs-like particle about 10 GeV? • A high luminosity B factory would be the ideal place to discover/study it, e.g. looking at - decay into τ+τ- ():Lepton universality test (M.A.S.L.,arXiv:0709.3747) -direct searches for monochromatic photons Dermisek, Gunion and McElrath, hep-ph/0612031 ( alsoMangano and Nason in  γμμ decays, arXiv:0704:1719 ) • Closely related topics: Bs decay, muon g-2 anomaly, light dark matter … Miguel-Angel Sanchis-Lozano IFIC-Valencia

  30. Conclusions II • Perspectives for a Super Flavour Factory On the physics case “Pushing the high-energy frontier, i.e. increasing the centre-of-mass energy in order to produce and observe new particles, is not the only way to look for NP. New particles can reveal themeselves through their virtual effects … the name of the game is rather high precision”arXiv:0710.3799 Browder, Ciuchini, Gershon, Hazumi, Hurth, Okada and Stocchi • However, there could still exist Higgs-like particles whose mass is low enough to be produced (not only virtually) at a Super Flavour Factory • The seek of these states is complementary/prior to other searches to be performed at LHC/ILC Miguel-Angel Sanchis-Lozano IFIC-Valencia

  31. Back up Miguel-Angel Sanchis-Lozano IFIC-Valencia

  32. Proposal of testing lepton universality (to the percent level) @ a (Super) B factory hep-ph/0610046 With the machine sitting on the (3S)Final state & BF (3S)  π+π- (1S,2S) →+- π+π- +- BF  2-4 x 10-2 BF  2 x 10-2 BF  4 - 8 x 10-4 (3S)  π+π- (1S,2S) →  +- π+π-l +l- BF  10-1  +- → l+l- X, l = e, BF  5 - 10 x 10-5 (3S)  +-+- BF  2 x 10-2 BF  2 x 10-2 (3S)   +- l +l- X → l+l - X, l = e, BF  2 x 10-3 With the machine sitting on the (4S) (4S)  π+π- (1S,2S) →+- π+π- +- BF  10-4 BF  2 x 10-2 BF  2 x 10-6 (4S)  π+π- (1S,2S)→  +- π+π-l +l- X BF  10-1  +- → l+l - X, l = e, BF  2 x 10-7 Compare rates Compare rates Statistical error ≈ 0.07 / √ # fb-1 Systematic error ≤ 0.037 Compare rates Miguel-Angel Sanchis-Lozano IFIC-Valencia

  33. Light Higgs windows at LEP (2HDM(II)) hep-ex/0408097 hep-ex/0408097 Excluded (mA,mh) region independent of theCP even Higgs mixing angle , from flavor-independent and b-tagging searches at LEP interpreted according to a 2HDM(II) Excluded regions in the (mA,tanβ) plane for different choices of . In the MSSM -/2  0 ; in a general 2HDM(II) -/2  /2 Miguel-Angel Sanchis-Lozano IFIC-Valencia

  34. g-2 muon anomaly in a 2HDM(II) A light pseudoscalar Higgs might be necessary to explain the g-2 anomaly  Cheung & Kong hep-ph/0302111   h, A One.loop vertex correction   f  h, A   Two-loop vertex correction The 2σ allowed regions in the (mA,mh) plane due to the constraints of a and Rb for tanβ=40. The blue region is where the total 2 is less than 4 while the yellow region is where the total 2 is less than the 2 (SM) Miguel-Angel Sanchis-Lozano IFIC-Valencia

  35. Domain walls • NMSSM has a Z3 symmetry implying 3 separate but degenerate vacua Causally disconnected regions of space could choose different vacuum • Non-renormalizable operators breaking Z3 would lead to a preference for one particular vacuum Large anisotropies in the cosmic microwave background in contradiction with WMAP Miguel-Angel Sanchis-Lozano IFIC-Valencia

  36. Light dark matter relic abundance • Light dark matter candidate from the NMSSM: the lightest neutralino χ0 • Current abundance of dark matter has to be explained through the annihilation into SM particles. χ0 χ0  A0  f f • The annihilation cross section has to be large enough to predict the current neutralino relic density • Recent limits from CLEO and Belle on invisible decay of quarkonium do not apply to a (pseudo)scalar mediator   χ0χ0 requires a vector mediator! Miguel-Angel Sanchis-Lozano IFIC-Valencia

  37. The Higgs sector in the SM One doublet of two complex fields (four real fields) Four degrees of freedom Spontaneous Symmetry Breaking + Higgs mechanism SM Higgs W+ W- Z0 become massive while  remains massless SM Higgs coupling to fermions < H0 > = v / √2 v=246 GeV Miguel-Angel Sanchis-Lozano IFIC-Valencia

  38. Conclusions (epilog) • The search for a light non-standard Higgs and the study of its associated phenomenology is possible at BaBaR with the machine running off the (4S) • Test of lepton universality (at the few percent level) could provide a first glimpse of such new physics • About 10 fb-1 at (3S) would be required to carry out the search for the radiative decays of  resonances to leptons mediated by a light A0 • A Super Flavour Factory would be the ideal place where following uo this investigation with an unprecedented precision Thanks! Miguel-Angel Sanchis-Lozano IFIC-Valencia

More Related