1. Shinya KANEMURA 1 Shinya Kanemura (Osaka Univ.) Discovery of Higgs and SUSY to Pioneer Particle Physics in the 21 st Century@Univ. of Tokyo, Nov 24-25. 2005 Discovery of Higgs and SUSY to Pioneer Particle Physics in the 21 st Century@Univ. of Tokyo, Nov 24-25. 2005 Yoshitaka Kuno (Osaka), Toshihiko Ota (TU Munich) Masahiro Kuze, Tomoyasu Takai (Tokyo Inst. Tech.) A Study on muon (electron) to tau conversion in Deep Inelastic Scattering A Study on muon (electron) to tau conversion in Deep Inelastic Scattering

2. 2 Shinya KANEMURA Contents Introduction Physics Motivation Physics Motivation LFV Yukawa coupling (Higgs mediated LFV) LFV Yukawa coupling (Higgs mediated LFV) Tau associated LFV process Tau associated LFV process LFV Deep Inelastic Scattering processes LFV Deep Inelastic Scattering processes Cross sections and general features Cross sections and general features Muon beam Muon beam Electron beam Electron beamSummary

3. 3 Shinya KANEMURA Introduction

4. 4 Physics Motivation LFV is a clear signature for physics beyond the SM. Neutrino oscillation may indicate the possibility of LFV in the charged lepton sector. In new physics models, LFV can naturally appear. SUSY (slepton mixing) Borzumati, Masiero SUSY (slepton mixing) Borzumati, Masiero Hisano, Moroi, Tobe, Yamaguchi Hisano, Moroi, Tobe, Yamaguchi Zee model for the mass Zee Zee model for the mass Zee Models of dynamical flavor violation Hill et al. Models of dynamical flavor violation Hill et al. …. ….

5. 5 Shinya KANEMURA LFV in SUSY Slepton mixing induces LFV at one loop. Gauge boson mediation Higgs boson mediation Form factors: A 1 L,R ij, A 2 L,R ij, … Form factors: κ ij Kitano, Koike Okada Babu, Kolda Dedes, Ellis, Raidal Bortzmati, Masiero Hisano, Moroi, Tobe, Yamaguchi

6. 6 Shinya KANEMURA Decoupling property of LFV Gauge boson mediation : Higgs boson mediation : LFV Yukawa coupling Not always decouple in the large M SUSY limit Not always decouple in the large M SUSY limit Decouple in the large M SUSY limit

7. 7 Shinya KANEMURA LFV in SUSY scenario It is known that sizable LFV can be induced at loop due to slepton mixing. Up to now, however, no evidence for LFV has been observed at experiments. μ→e , μ→eee, …. This situation may be explained by large M SUSY, so that the SUSY effects decouple. Even in such a case, we may be able to search LFV via the Higgs boson mediation, which does not necessarily decouple for a large M SUSY limit.

8. 8 Shinya KANEMURA T au-associated LFV T au-associated LFV The tau associated LFV is interesting for Higgs mediation, which is proportional to the Yukawa coupling The tau associated LFV is interesting for Higgs mediation, which is proportional to the Yukawa coupling (Different behavior from μe mixing case.) (Different behavior from μe mixing case.) Tau associated LFV is less constrained by current data as compared to theμ ⇔ e mixing Tau associated LFV is less constrained by current data as compared to theμ ⇔ e mixing  → e  1.2 ×10 ＾（－ 11 ）  →3e 1.1 ×10 ＾（－ 12 ）  Ti → e Ti 6.1 ×10 ＾（－ 13 ）  →  3.1 ×10 ＾（－ 7 ）  →  (1.4-3.1) ×10 ＾（－ 7 ）  →  3.4 ×10 ＾（－ 7 ）  ⇔   ⇔ e

9. 9 Shinya KANEMURA Experimental bounds on LFV parameters  31 (tau-e mixing)  →  e    For  31 (tau-e mixing), similar bound is obtained from  →  e    The strongest bound on   (tau-mu mixing) comes from the, τ→  results. The strongest bound on (A 2 L,R ) ij comes from the  →  e  →  e  →  results. the  →  e  →  e  →  results. Higgs boson mediation Gauge boson mediation

10. 10 Shinya KANEMURA Search for Higgs mediated τ- e & τ- μ mixing at future colliders Tau’s rare decays at B factories. τ→eππ （ μππ ） τ→eππ （ μππ ） τ→eη (μη) τ→eη (μη) τ→μe e (μμμ), …. τ→μe e (μμμ), …. In near future, τ rare decay searches may improve the upper limit by about 1 order of magnitude. In near future, τ rare decay searches may improve the upper limit by about 1 order of magnitude. We here discuss the alternative possibilities. The DIS process μ Ｎ (eN)→τ Ｘ at a fixed target experiment at a neutrino factory and a LC The DIS process μ Ｎ (eN)→τ Ｘ at a fixed target experiment at a neutrino factory and a LC

11. 11 Shinya KANEMURA LFV Deep Inelastic Scattering

12. 12 Shinya KANEMURA Deep inelastic scattering LFV process DIS μ Ｎ →τ Ｘ process: At a future neutrino factory At a future neutrino factory (or a muon collider), about (or a muon collider), about 10 20 muons/year of energy 50 GeV 10 20 muons/year of energy 50 GeV (or 100-500 GeV) can be available. (or 100-500 GeV) can be available. DIS process e Ｎ →τ Ｘ process: At a LC (E cm =500GeV (or 1TeV), At a LC (E cm =500GeV (or 1TeV), L=10 34 /cm 2 /s) 10 22 electrons/year of L=10 34 /cm 2 /s) 10 22 electrons/year of 250GeV (or 500GeV) electrons available. 250GeV (or 500GeV) electrons available. A fixed target experiment option of a LC

13. 13 Shinya KANEMURA The cross section in SUSY CTEQ6L Sub-process e - q →τ - q is proportional to the down-type quark mass. the down-type quark mass. Probability for the b-quark is larger for higher energies. For Ee > 60 GeV, the total cross section is enhanced the total cross section is enhanced due to the b-quark sub-process due to the b-quark sub-process Ee ＝ 50 GeV 10 -5 fb Ee ＝ 50 GeV 10 -5 fb 100 GeV 10 -4 fb 100 GeV 10 -4 fb 250 GeV 10 -3 fb 250 GeV 10 -3 fb Higgs mediated LFV process

14. 14 Shinya KANEMURA Angular distribution μLμL τRτR θ Target Lab-frame Higgs mediation → chirality flipped → chirality flipped → （ 1 － cos  cm ） 2 → （ 1 － cos  cm ） 2  From the μ L ( e L ) beam, τ R is emitted to the backward direction due to (1 ー cosθ CM ) 2 nature in the CM frame.  In Lab-frame, tau is emitted forward direction with some P T.

15. 15 Shinya KANEMURA Energy distribution for each angle  From the e L beam,  R is emitted to the backward direction due to to the backward direction due to (1 ー cos  ) 2 nature in the CM frame. (1 ー cos  ) 2 nature in the CM frame.  In Lab-frame, tau is emitted forward direction but with large angle with a P T. direction but with large angle with a P T. E ＝ 100 GeV E ＝ 500 GeV E ＝ 50 GeV

16. 16 Shinya KANEMURA Contribution of the gauge boson mediation τ→eγ results gives the upper bound on the tensor coupling, therefore on the e N →τX cross section Gauge mediated LFV ⇒ No bottom Yukawa enhancement At high energy DIS e N →τX process is more sensitive to the Higgs mediation than the gauge mediation.

17. 17 Shinya KANEMURA Experiments Near future CERN μbeam (200GeV) CERN μbeam (200GeV) SLAC LC (50GeV) SLAC LC (50GeV)Future Nutrino Factory, muon collider Nutrino Factory, muon collider ILC fixed targed option ILC fixed targed option Target: muon beam 100g/cm^2 electrom beam 10g/cm^2

18. 18 Shinya KANEMURA Muon beam

19. 19 Shinya KANEMURASignal # of tau for L =10 20 muons |κ32| 2 =0.3×10 -6 : |κ32| 2 =0.3×10 -6 : Eμ ＝ 50 GeV 100×ρ[g/cm 2 ] τ’s Eμ ＝ 50 GeV 100×ρ[g/cm 2 ] τ’s 100 GeV 1000 100 GeV 1000 500 GeV 50000 500 GeV 50000 Hadronic products τ→π 、 ρ, a 1, … ＋ missings τ→π 、 ρ, a 1, … ＋ missings Hard hadrons emitted into the same direction as the parent τ’s τ R ⇒ backward ν L + forward π,ρ 、 … τ R ⇒ backward ν L + forward π,ρ 、 … Bullock, Hagiwara, Martin

20. 20 Shinya KANEMURA Backgrounds Hard muons from DIS μN→μX may be a fake signal. Rate of mis-ID [machine dependent] Rate of mis-ID [machine dependent] Emitted to forwad direction without large P T due to Ratherford scattering Emitted to forwad direction without large P T due to Ratherford scattering 1/sin 4 (θc M /2) 1/sin 4 (θc M /2) Energy cuts Hard hadrons from the target (N ) Realistic Monte Carlo simulation is necessary to see the feasibility

21. 21 Shinya KANEMURA Signal Backgrounds Higgs boson mediation photon mediation Different distribution ⇒ BG reduction by E τ, θ τ cuts

22. 22 Shinya KANEMURA Monte Carlo Simulation 500GeV muon beam Generator: Signal Modified LQGENEP (leptoquark generator) (leptoquark generator) Bellagamba et al Bellagamba et al Background LEPTO γ ＤＩＳ Background LEPTO γ ＤＩＳ Q 2 >1.69GeV 2,σ=0.17μ ｂ Q 2 >1.69GeV 2,σ=0.17μ ｂ MC_truth level analysis MC_truth level analysis Work in progress

23. 23 Shinya KANEMURA Electron beam

24. 24 Shinya KANEMURA Number of produced taus Ee ＝ 250 GeV, Ee ＝ 250 GeV, L =10 34 /cm 2 /s, ⇒ 10 22 electrons L =10 34 /cm 2 /s, ⇒ 10 22 electrons In a SUSY model with |κ 31 |^2=0.3×10 -6 : In a SUSY model with |κ 31 |^2=0.3×10 -6 : σ= 10 -3 fb = 6 x 10 -42 cm 2 σ= 10 -3 fb = 6 x 10 -42 cm 2 N τ = ρ N A N e σ N τ = ρ N A N e σ 10 5 of τleptons are produced for 10 5 of τleptons are produced for the target of ρ=10 g/cm^2 the target of ρ=10 g/cm^2 Naively, non-observation of the high energy muons from the tau of the e N → τ X process may improve the current upper limit on the eτΦ coupling 2 by around 4 orders of magnitude. Naively, non-observation of the high energy muons from the tau of the e N → τ X process may improve the current upper limit on the eτΦ coupling 2 by around 4 orders of magnitude. N A =6 x 10 23

25. 25 Shinya KANEMURA Signal/Backgrounds Signal: for example, μ from τ in e N→τX Backgrounds: Pion punch-through Pion punch-through Muons from Pion decay-in-flight Muons from Pion decay-in-flight Muon from the muon pair production Muon from the muon pair production Monte Carlo Simulation 250GeV-1.5 TeV electron beam 250GeV-1.5 TeV electron beam Event Generator Signal: modified LQGENEP Event Generator Signal: modified LQGENEP Background: LEPTO γ ＤＩＳ Background: LEPTO γ ＤＩＳ BG absorber, simulation for the pass through probability of e, π, μ by using GEANT BG absorber, simulation for the pass through probability of e, π, μ by using GEANT

26. 26 Shinya KANEMURA High energy muon from tau can be a signal Geometry (picture) ex) target ρ=10g/cm 2 Backgrounds Muon from  DIS Muon from  DIS Muon from pair paroduction (dilepton) Muon from pair paroduction (dilepton) Pion punch-through Pion punch-through Muons from Pion decay-in-flight Muons from Pion decay-in-flight ……. ……. e μ τ Hadron absorber Muon spectrometer (momentum measurement) (water) (iron) e elemag shower π Monte Carlo simulation LQGENEP, LEPTO, GEANT4 10cm6-10m target dump

27. 27 Shinya KANEMURA μ τ target Muon spectrometer (momentum measurement) e μ r r gap Cuts: E μ, r, r gap, Q 2

28. 28 Shinya KANEMURA MC analysis (under study) (LQGENEP, LEPTO, GEANT4) LC Ee=250GeV, 500GeV, 1TeV, 1.5TeV L=10 22 electrons per year L=10 22 electrons per year Signal muons from LFV DIS Signal muons from LFV DIS e N →τX with τ→μνν e N →τX with τ→μνν 10 4-5 muons/year 10 4-5 muons/year Background muons from γDIS, etc Kinematic cuts 1. E  (muon energy cut) 1. E  (muon energy cut) 2. P T or r (angle cut) 2. P T or r (angle cut) 3. rgap (extrapolate back cut) 3. rgap (extrapolate back cut) 4. Q 2 cut: Q 2 >10GeV 2 4. Q 2 cut: Q 2 >10GeV 2 But with 10 8 MC events, the number of the MC background event is reduced to 1. the number of the MC background event is reduced to 1. Simulation with more MC events (10 9-10 ) is work in progress.

29. 29 Shinya KANEMURA Values of the cross section Number of MC events 10,000,000 Cross sections of produced taus (and muons from them) After the cuts by Et, r, rgap, the values where the number of the MC background event becomes 1 More MC events necessary! Takai

30. 30 Shinya KANEMURA Event number 100,000,000 (10 times greater) S/N where the MC events becomes 1. Takai

31. 31 Shinya KANEMURASummary We discussed LFV via DIS processes μ Ｎ （ e N ） →τX using high energy muon and electron beams and a fixed target. For E > 60 GeV, the cross section is enhanced due to the sub-process of Higgs mediation with sea b-quarks DIS μN→τX by the intense high energy muon beam. In the SUSY model, 100-10000 tau leptons can be produced for Eμ=50-500 GeV. In the SUSY model, 100-10000 tau leptons can be produced for Eμ=50-500 GeV. No signal in this process can improve the present limit on the Higgs LFV coupling by 10 2 – 10 4. No signal in this process can improve the present limit on the Higgs LFV coupling by 10 2 – 10 4. Theτ is emitted to forward direction with P T Theτ is emitted to forward direction with P T The signal is hard hadrons from τ→πν 、 ρν, a 1 ν,...., which go along the τdirection. The signal is hard hadrons from τ→πν 、 ρν, a 1 ν,...., which go along the τdirection. Main background: mis-ID of μ in μN→μX…. Main background: mis-ID of μ in μN→μX…. DIS process e N →τX : At a LC with E cm =500GeV ⇒ σ ＝ 10 -3 fb At a LC with E cm =500GeV ⇒ σ ＝ 10 -3 fb L=10 34 /cm 2 /s ⇒ 10 22 electrons available L=10 34 /cm 2 /s ⇒ 10 22 electrons available 10 5 of taus are produced for ρ=10 g/cm 2 10 5 of taus are produced for ρ=10 g/cm 2 Non-observation of the signal (high-energy muons) Non-observation of the signal (high-energy muons) would improve the current limit by 10 4. would improve the current limit by 10 4. Realistic simulation: work in progress (collecting more MC events).

32. 32 Shinya KANEMURA Takai

33. 33 Shinya KANEMURA A source of slepton mixing in the MSSM+RN Slepton mixing induces both the Higgs mediated LFV and the gauge mediation. The off-diagonal elements in the slepton mass matrix can be induced at low energies, even when it is diagonal at the GUT scale. RGE RGE

34. 34 Shinya KANEMURA The gauge boson mediation v.s. the Higgs mediation For relatively low m SUSY, the Higgs mediated LFV is constrained by current data for the gauge mediated LFV. For m SUSY > O(1) TeV, the gauge mediation becomes suppressed, while the Higgs mediated LFV can be large.

35. 35 Shinya KANEMURA Takai Eπ ＞ 50GeV, θπ ＞ 0.025rad ⊿ μ 0.01rad Hadrons from μN→τX and backgrounds Scattering angle ofμis small, it would be difficult to tag background events for reduction Work in progress

36. 36 Shinya KANEMURA m SUSY ～ O(1) TeV Consider that m SUSY is as large as O(1) TeV with a fixed value of |μ|/m SUSY Gauge mediated LFVis suppressed Gauge mediated LFV is suppressed, while the Higgs-LFV coupling κ ij while the Higgs-LFV coupling κ ij can be easily as large as the current experimental limit. Babu,Kolda; Babu,Kolda; Brignole, Rossi Brignole, Rossi Prediction on LFV Yukawa

37. 37 Shinya KANEMURA Current Data for rare tau decays