Searching for New Physics with Rare Decays:

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1 Searching for New Physics with Rare Decays: Results and prospects for π νν and π e ν Douglas Bryman University of British Columbia 11/20/2008 INT Seattle 1

2 Standard Model Not likely the whole story Not so long ago, prominent theorists were fond of seeing the light at the end of the tunnel Cosmological issues: inflation, dark matter, dark energy, matter anti-matter asymmetry Theoretical issues: gravity, neutrino mass, flavor problem, hierarchy problem, LHC: Direct exploration of the TeV energy scale. Flavor Physics (e.g. Rare Decays): Explore the symmetry properties of new degrees of freedom at high mass scales TeV. 11/20/2008 INT Seattle 2

3 Light Particle Rare Decay Experiments Exotic Searches New physics if seen; SM effects are negligible. BSM Physics New physics if deviations from well-calculated SM predictions occur. State of the art: single event sensitivity, L μ e ( πμ e) LFV μ eγ LFV μ N en LFV π f "Axions" 0 + π μ ν T-violation L 0 L + μ μ π νν π νν 0 0 L + π ( ) e ν π ( ) μ ν V V CP violation Lepton Universality < < < : 6200 events : 7 events 10-4 : 4x10 5 events + 11/20/2008 INT Seattle 3 td td

Events Observed SM SM Events O(100) O(1000) New Physics Example (MFV): πνν 0 0 L vs.

4 πνν : Great Discovery Potential. SM: B( πνν) = 0.85 ± 0.07x10 10 B( πνν) = 0.30 ± 0.06x L 0 0 L ( ) πνν BR/ BR vs. Events Observed SM SM Events O(100) O(1000) New Physics Example (MFV): πνν 0 0 L vs. πνν Littlest Higgs Model with T-parity Run Duration (Hours*) M. Blanke, et al.,arxiv:hep-ph/ *AGS 11/20/2008 INT Seattle 4

5 πνν Experiments Sensitivity or Limit vs. Yr. 0 0 π νν TEV E2008 L π νν SM π νν π νν 0 0 L BNL 3 events + π + νν Br( πνν) < (8.22 ± 0.84) x10 SM Br( πνν) < (2.76 ± 0.40) x L SM 11/20/2008 INT Seattle 5

BNL E787/949 Measurement of + π + νν CANADA-CHINA-JAPAN-RUSSIA-USA Collaboration: Institute for Nuclear Research (Moscow), Institute for High Energy Physics (Protvino), University of New Mexico,

6 BNL E787/949 Measurement of + π + νν CANADA-CHINA-JAPAN-RUSSIA-USA Collaboration: Institute for Nuclear Research (Moscow), Institute for High Energy Physics (Protvino), University of New Mexico, Princeton University, Brookhaven National Laboratory, TRIUMF, University of British Columbia, Tsinghua University (Beijing), Stony Brook University, Fermilab, yoto University, E, University of Alberta, Fukui University, Osaka University, National Defense Academy (Japan) Advanced Technologies: Highest Efficiency Detection Low mass central tracking chamber - inflated cathodes 500 MHz digitizers Scintillating fiber target Pure CsI calorimeter Blind Analysis 11/20/2008 INT Seattle 6

7 Momentum Spectra + Decay (Standard Model) V-A, S, T

Previous measurements E787/E949 Above π2 peak: 3 events Below π2 peak: limit +1.

8 Previous measurements E787/E949 Above π2 peak: 3 events Below π2 peak: limit B( + π + νν)= B( + π + νν)< b.g.=1.22±0.24 events. 11/20/2008 INT Seattle 8

9 Correlation + π 0 γ Lower E π + γ E787 E949 π 0 Veto power E949 E787 11/20/2008 INT Seattle 9

10 Before any cuts pnn2 signal region inematics π μ Extra particle Photon veto ink

11 Blind Analysis Strategy Mask the signal region. Develop the cuts and estimate the background (1/3 data); use data as much as possible in the background estimates. Bifurcated background analysis with (2/3) of data. Study correlations. Open the box. π2 Cut-2; PV threshold signal Cut-1; target pulse : 1=target scatt. 2=photon veto e4 : 1=Tπ + Te 2=MC : 1=kinematics 2=π μ e e4 μ2

12 + π + π 0 background PV Correlation π 0 γ PV*scatt + Lower E γ π PV rejection factor Selection criteria

13 + π + π - e + ν (e4) background e4 candidate (data) e4 MC event + π + π - π + νν e +

14 Correlation study Signal box Cut-2 N 1 eep signal region blinded Relax photon veto or ccd (target) pulse cut Check the predicted events and observed events in the extended region. 1 M Cut-1 11/20/2008 INT Seattle 14

15 PNN2 Background summary Sensitivity 11/20/2008 INT Seattle 15

16 3 New events observed A B C 11/20/2008 INT Seattle 16

17 Final results from E787/E949 7 events observed + πνν + = x B ( ) Probability that All 7 events are due to background: 0.001

18 Final Goal 11/20/2008 INT Seattle 18

19 π π e νγ ( ) μν( γ) R = ± x10 th e/ μ ( ) 4 W. Marciano V. Cirigliano Possibly the most accurately calculated decay process involving hadrons.. e ν ( ) 5 th = ± x e/ μ R * 10 Helicity suppression 5x π e ν Structure dependent radiation included? Finkemeier(1995) Cirigliano, Rosell(2007) 11/20/2008 INT Seattle 19

20 Beyond the Standard Model New PS interaction R-parity violating SUSY Marciano 0.1 % measurement Λ 1000TeV νη expected Others Lowest chargino mass Ramsey-Musolf -Leptoquarks -Excited gauge bosons -Compositeness -SU(2)xSU(2)xSU(2)xU(1) -...

21 Scalar Interactions: π eν vs. Super-allowed β Decay Campbell and Marbury (2003), Marciano CM Unitarity: Vud + Vus + Vub = (10) Γ( π e ν) 0.1% Precision 4 Re / μ = = 1.231(4) x10 ( now < 0.1%) Γ( π μ ν) Constraining new Physics? Direct Constraints Re/ μ : Λ A ~ 20 TeV, ΛP ~ 1000TeV! Unitarity: Λ ~ 20TeV, Λ ~ 12 TeV V Induced Current Constraints Re/ μ : ΛV ~ 2 TeV, Λ Unitarity: Λ ~ 2TeV A S S 11/20/2008 INT Seattle 21 () ~60 TeV! () Gμ π SM : ~ ; ΛSM ~ 440GeV 2 2Λ 2 SM Loops e.g. A induces V P induces S

22 Charged Higgs and Lepton Flavor Violation Masiero, Paradisi, Petronzio (2006) The unobserved neutrino involved in + π / e ν decay may be νe, νμ, or ντ d R Low Energy SUSY (with R parity*); Large tan β. R NP / R SM e μ = 1 r e/ μ e/ μ +Δ NP Current (Future) Experiments: Δ r < (0.0003) Δ r < 0.06 (0. 005) e/ μ e/ μ π 3B+L+2S *R Parity (MSSM): R=(-1) 11/20/2008 INT Seattle 22

23 i) FCNC M lν ; Δ r < P 4 e/ μ 6 NP ( ) ( ) ii) Lepton Flavor Violation M lν ; i = e, μ, k = τ. For Δ 510 l 11/20/2008 INT Seattle 23 2 e/ μ m P m τ 31 6 Δ rsusy = Δ P tan β P= π, mh me O (0.01), O (0.0003);,tan β ~40 Effects (optimistically!) in range of planned experiments. -10 For the parameters above R( τ μγ)~10 ; -7 (Present experiment (Babar/Belle) R( τ μ/ eγ)<10.) π Larger effects in B l ν, beyond reach of current experiments. i k

24 W l R e/μ = ν Γ(w eν) Γ(w μν) w g e 2 Μ lν l M ν Γ(π eν) R = e/μ Γ(π μν) g e 2 μ-e Universality g μ 2 π m e 2 g μ 2 m μ 2 Mode π eν/π μν eν/ μν τ eνν/τ μνν νe/νμ scatt. W decays πeν/ πμν g e /g μ ± ± ± ± ± ± 0.003** **M. Moulson INT 11/08

π eν e ν / R (±0.4%) expπ e / μ 1.2265(34)(44) x10 1.2346(35)(36) x10 4 TRIUMF (1992) 4 PSI (1993) R R 43(37) 10 th exp 8 e/ μ e/ μ = x Experiments μν 2.457 (32)x10 Ave.

25 π eν e ν / R (±0.4%) expπ e / μ (34)(44) x (35)(36) x10 4 TRIUMF (1992) 4 PSI (1993) R R 43(37) 10 th exp 8 e/ μ e/ μ = x Experiments μν (32)x10 Ave * R R 20(32) 10 th exp 8 e/ μ e/ μ = x * RWanke. (2008) R (±1.3%) exp e / μ Two new π e ν experiments. ( ) -8 ± Goal: ± (10)x10 ( 03%. ) -8 Goals: (5)x % New e ν experiment at CERN. 11/20/2008 INT Seattle 25

26 New π + e + ν Experiments expπ Precision Goals for R e / μ : < 0.1% TRIUMF PIENU PSI PIBETA Spectrometer ASU, BNL, Osaka, TRIUMF, UBC, VPI INS (Pol.), IHEP, JINR, PSI, RBI, Virginia, Zurich 11/20/2008 INT Seattle 26

27 PIENU: Measurement of (π eν)/ (π μν) Branching Ratio at TRIUMF Collaboration A. Aguilar-Arevalo M. Aoki, M. Blecher, D. Bryman, J. Comfort, J. Doornbos, L. Doria, P. Gumplinger, A. Hussein, Y. Igarashi, N. Ito, S. ettell, Y. uno, L. urchaninov, L. Littenberg, C.Malbrunot, G. Marshall, A.Muroi, T. Numao, R. Poutissou, F. Retiere, A. Sher, and. Yamada Osaka University, VPI, University of BC, Arizona State University, TRIUMF, UNBC, BNL, E

28 Experiment Concepts Low Momentum π Beam at p=75 MeV/c. πs lose energy and stop in a target of plastic scintillator. Scintillation detectors viewed by photo-multiplier tubes and all signals are digitized at 500 MHz. π μ e NaI e π π + μ ( γ ) e ( γ ) τ π = 26 ns, τ = 2200ns μ Extra pulse T = 4.2( 3.3) MeV μ 11/20/2008 INT Seattle 28 for π μ e only.

29 Measure positron energies in a NaI(Tl) crystal spectrometer (no magnetic field!): π e ν Pe = 70 MeV / c π μ ν Pμ = 30 MeV / c T = 4.2 MeV, R = 1.4mm μ + μ e νν Pe = 0 53MeV Electrons have fairly uniform interactions over the Systematic effects cancel (to 1 de e.g. solid angle, Multiple Coulomb Scattering,, annihilati dx μ st order) in the ratio NaI(Tl) 11/20/2008 INT Seattle 29 e π π + μ ( γ ) e ( γ ) range P[1-70 MeV] : Γ( π e) ( π μ e) Γ on, bremsstrahlung, timing. N.B.: When aiming for high precision: must rely on measurements for corrections rather than simulations whenever possible!

30 Previous TRIUMF Experiment Britton et al. (1993) τ π = 26ns τ μ = 2.2μs 11/20/2008 INT Seattle 30

31 ASU BNL E Osaka TRIUMF UNBC UBC VPI TRIUMF PIENU Experiment Γ( π e ν( γ)) ( π μ ν( γ) ) Γ Precision Goal < 0.05% Order of Magnitude improvement BNL E949 CsI BINA 2% BINA 48cmϕ x48cm BNL NaI(Tl) 11/20/2008 INT Seattle 31

32 Beamline New extension Momentum selection + Absorber Positron suppression -Select momentum. -Use de/dx difference. -2 nd momentum analysis to select pions.

33 Tail correction π eν Τπ+ΔΕe π μ e Τπ+ΔΕe+Eμ π μ e Timing cut Timing+Energy cuts 4 MeV 11/20/2008 INT Seattle 33

34 Expected precision Sources E248 PIENU Statistical error Low energy tail (π eν) Acceptance difference Pion lifetime Others Total error /20/2008 INT Seattle 34

35 Beam test results Beam into NaI Positron suppression: Measured (at M9A) 2.5/1 1/10 Expected (M13 ext.) 1/50> π/e separation at M13 F3 Energy resolution of NaI: 2 %. Target energy resolution: π e

36 Beam line status The new beamline extension is complete.

37 Detector Status -NaI-CsI System: assembly complete and installed -Scintillators in production. -Drift chambers being tested. -Si-strips: being tested.

38 Prospects for Measurements of πνν 11/20/2008 INT Seattle 38

39 Following up on E949: SPS primary p: 400 GeV/c Secondary beam: 75 GeV/c, 800 MHz π//p (~6% + ) CERN NA62 : + + πνν Goal: >80 events for B( πνν) = 10 Measure,, P P π θ π 0 Hermetic detector for Decays μ I.D. = 5x π γγ ε = π MHz + π + (ABES) ~11 MHz of + decays ν ν ΔP ΔPπ Resolutions: ~ 0.3%, ~ 1%, Δθπ ~ 60μrad P P 11/20/2008 INT Seattle 39 π

40 Something even harder! Limit from 0 0 L Theory: πνν πνν ( ± ) x10 via Experiments 11 9 isospin : < 1.4 x10 [ Grossman, Nir ] TEV (FNAL) result: E E391a: B( πνν) < 5.9 x10 (90% CL) L B( πνν) < 2.1x10 (90% CL) L JPARC Proposal: Single event Sensitivity OPIO Concept : <10 Fermilab Project X? 11/20/2008 INT Seattle 40

41 E PS E391a >>> JPARC with TEV CsI Features: * Pencil Beam * Pilot Project for JHF * High acceptance * Test reliance on extreme * High P T selection photon veto efficiency πνν < L 2008 Result: B( ) 6.7 x10 (90% CL) 11/20/2008 INT Seattle 41

42 πνν and L 0 0 πνν at Fermilab Project X (8 GeV 200kW) or at J-PARC High intensity, 100 % duty factor of Project X is ideal for the TOF-based L experiment and very low energy + beams. Even 20-30% d.f. at J- PARC will work. Exploit advances in instrumentation >1000 events attainable in 4-5 years 3% precision Even higher intensities could be used 11/20/2008 INT Seattle 42

measurements High acceptance and precise π + momentum measurement to suppress 0 π π, μ ν backgrounds

43 Compact High Field System for + π + νν Improvement of techniques developed at BNL E787/949 Low P ~400 MeV/c for high stopping efficiency Sci-Fi target and range stack for high rate γ Veto π μ e measurements High acceptance and precise π + momentum measurement to suppress 0 π π, μ ν backgrounds "Ideal" homogeneous photon veto e.g. LXe 20 X 0 Range Stack 11/20/2008 INT Seattle T Low mass tracker

πνν Experiment Concept 0 0 L 8 GeV Protons

with pointing calorimeter 4 π solid angle

44 πνν Experiment Concept 0 0 L 8 GeV Protons 200 ps Use TOF to work in the c.m. system 0 L Identify main 2-body background L ππ 0 Reconstruct π γγ decays with pointing calorimeter 4 π solid angle photon and charged particle vetos 0 0 L π νν 11/20/2008 INT Seattle 44

45 Summary πνν Experiments Sensitivity or Limit vs. Yr. 0 0 π νν TEV E2008 L π νν SM π νν π νν 0 0 L BNL 7 CERN NA62 J-PARC π νν 0 0 π νν L Project-X/J-PARC? 1000 events??? High duty factor; Long running. 11/20/2008 INT Seattle 45

46 Precision π + e ν e ν (2006) 0.4% <1% CERN NA % TRIUMF PIENU PSI PEN 11/20/2008 INT Seattle 46

47 Summary Rare decays have important roles to play in the search for new physics. Future prospects for pion, muon and kaon rare decay experiments are good. 11/20/2008 INT Seattle 47

The PIENU Experiment

The PIENU Experiment For the PIENU Collaboration A. Aguilar-Arevalo 11, M. Aoki 4, M. Blecher 9, D.I. Britton 8, D. Bryman 6, S. Chen 10, J. Comfort 1, L. Doria 5, P. Gumplinger 5, C. Hurst 6, A. Hussein