Searches for New Physics with the TREK Detector

Transcription

1 Searches for New Physics with the TREK Detector Steffen Strauch for the TREK Collaboration University of South Carolina Supported in parts by the U.S. National Science Foundation: NSF PHY-578 XIIth International Conference on Heavy Quarks and Leptons Schloss Waldthausen, Mainz, Germany, August 5-9, 014

2 Outline J-PARC experiment E06, Jun Imazato and Michael Kohl, spokespeople. E06 is stage 1 approved. J-PARC experiment E36, Michael Kohl and Suguru Shimizu, spokespeople. E36 is stage 1 and approved. Aerial view of J-PARC The TREK Program - Study of rate Kaon decays Exp. (K Intensity) 1 Search for T violation in kaon decays π 0 µ + ν µ E06 (0-70 kw) Search for lepton universality violation in a measurement of the ratio of the K e and Kμ decay widths 3 Search for a heavy sterile neutrino e + ν(γ ) µ + ν(γ ) e + N µ + N E36 (30-50 kw) 4 Search for a light neutral gauge boson π + e + e µ + νe + e

3 The TREK E06/E36 detector will be the upgraded detector of KEK E46 KEK E46 experiment: Observables: µ + momentum, π 0 momentum, and µ + polarization Beam K + Cherenkov (K/π separation) r v C-Counter Quad z Pb m + C3 C4 C TOF Polarimeter CsI(Tl) Target/Ring Muon polarimeter (transverse μ + polarization) 1-Sector Toroidal spectrometer (charged particle momentum) CsI(Tl) calorimeter (π 0 detection, photon momentum) Active target (reaction vertex information) Κ + π 0 µ + ν µ Gap Coil Target CsI (Tl) Iron pole + stopper e + counter TREK detector: Upgrade of E46 detector for the study of various Kaon decay channels at J-PARC. Figure of E46 setup from M. Abe et al., Phys. Rev. D 73, (006) 3

4 T-odd polarization asymmetry in K + µ3 decay up-down asymmetry in electron distribution in subsequent muon decay P T Κ + π 0 µ + ν µ π 0 ν µ µ + K + study of direct CP violation, possibly due to non-standard mechanisms, with the help of T-odd correlation variables K+ decay in its rest frame Most stringent upper bound set by KEK-E46 collaboration: P T < 5 x -3 at 90% C.L. P T =! σ µ (! p π! p µ )! p π! p µ M. Abe et al., Phys. Rev. Lett. 83, 453 (1999); M. Abe et al., Phys. Rev. Lett. 93, (004); M. Abe et al., Phys. Rev. D 73, (006) 4

5 P T is sensitive to new physics KEK-E46: P T < 5-3 at 90% C.L. Projected J-PARC E06: P T < -4 at 90% C.L. S.M. incl. FSI S.M. u s u ū W + (q) µ + ν µ P T vanishes in the SM at the tree-level P T potential for physics beyond the standard model Multi-Higgs, SUSY with squarks mixing, SUSY with R-parity breaking, Leptoquark model SM background u Charged Higgs boson contribution to K + μ3 s u ū H + (q) µ + ν µ G. López Castro, L. López-Lozano and A. Rosado, Phys. Rev. D 80, (009) 5

6 TREK sub-detector upgrade for E36 J-PARC K1.1BR! 800 MeV/c K + Cryostat Iron Pole Lead Shield e + C Cherenkov C1 CsI(Tl) C4 PGC C3 TOF Target Fiber Fiber target Finer segmentation of target scintillating fibers. Readout: MPPC (SiPMT) via wavelength shifting fibers. Spiraling Fiber Tracker (SFT) Double-layer fibers in helicities wrapped around target bundle for near target vertex reconstruction. B0 Degrader TOF1, Aerogel Cherenkov FADC readout of CsI(Tl) Improved pileup analysis m M 1 m 6

7 Improved e/μ particle separation with upgraded TREK detector J-PARC K1.1BR! 800 MeV/c K + Cryostat Iron Pole Lead Shield e + C Cherenkov C1 CsI(Tl) C4 PGC C3 TOF Target Fiber P mis = probability of µ + mis-identification as e + Time of flight (TOF1, TOF) σ t < 0 ps, P mis (TOF) = 7 x -4 e + trigger by Aerogel Cherenkov detector (AC) ε(e + ) > 98%, P mis (AC) = 0.03 B0 Degrader TOF1, Aerogel Cherenkov Lead glass Cherenkov detector (PGC) ε(e + ) > 98%, P mis (PGC) = m M P mis (Total) = P mis (TOF) P mis (AC) P mis (PGC) 1 m = 8 7 < 6 7

8 The Kl decay in the Standard Model K + e + ν(γ ) K + µ + ν(γ ) s K + W + u g e e + ν e s K + W + u g µ µ + ν µ Decay-width Γ(K l ) = g l (G / 8π ) f K m K m { l 1 (m l / m K )} Decay-width ratio hadronic form factor f K cancels V. Cirigliano and I. Rosell, Phys. Rev. Lett. 99, (007) R SM K = Γ(K + e + ν e [γ ]) Γ(K + µ + ν µ [γ ]) = m e m µ m K m e m K m µ (1+ δ R QED ) =.477(1) 5 g e / g µ = 1 in the standard model helicity suppression radiative correction (incl. internal brems., IB) 8

9 R K as probe of new physics effects R K sensitive to lepton flavor violating effects Large contributions to R K, ΔR/R O(1%), from SUSY lepton-flavor violating contributions Strong constraints to SUSY contributions to R K from B-meson decays, ΔR/R O(0.1%) A. Masiero, P. Paradisi, and R. Petronzio, Phys. Rev D 74, (R) (006) R.M. Fonseca, J.C. Romão, A.M. Teixeira, Eur. Phys. J. C 7, 8 (01) R K sensitive to neutrino mixing parameters within SM extensions involving a fourth generation of quarks and leptons R K constrains fourth generation of quarks and leptons 1 U e4 1 U µ 4 H. Lacker and A. Menzel, JHEP07, 006 (0) R K sensitive to neutrino mixing parameters within SM extensions involving sterile neutrinos R K depends on masses, hierarchy, and mixings of new neutrino states A. Abada, D. Das, A.M. Teixeira, A. Vicente, and C. Weiland, arxiv: v (01) 9

10 Determining R K from K e( γ), Kμ(γ) yields background signal + SD background R K = N(!K e ) Ω(!K µ ) N(!K µ ) Ω(!K e ) K e3 K µ(γ ) K e(γ ) Intensity (a.u.) K µ 3 1 / 40,000 1 / 3,000 1 /, k IB!K e = K e + K eγ IB!K µ = K µ + K µγ e + /µ + Particle separation crucial (momentum, TOF, AC, PGC) e or μ momentum (MeV/c) µ + mis-identification probability as e + to be < -6 Rejection of K e3 and Kμ3 (particle momentum) Inclusion of radiative decay K IB l, subtraction of K SD l (0 or 1, CsI(Tl))

11 Recent and projected measurements of R K Standard Model ΔR K /R K 0.04%! KLOE@DAΦNE ΔR K /R K 1.3%, K in-flight decay, low intensity kaon beam. R K = (.493 ± 0.031) -5 F. Ambrosino et al., Eur. Phys. J. C 64, 67 (009). NA6@CERN-SPS Sensitive probe of LFV dominant SUSY contribution + interference between SM and SUSY LFC terms (-3.%) dominant SUSY contribution (1.3%) A. Masiero, P. Paradisi, and R. Petronzio, Phys. Rev D 74, (R) (006) ΔR K /R K 0.4%, K in-flight decay, e/μ kinematical separation at high momentum, μ + in-flight decay. R K = (.488 ± 0.0) -5 C. Lazzeroni et al., Phys. Lett. B 719, 36 (013). Future NA6: ΔR K /R K = %. Projected TREK E36 projected uncertainties: ΔR K /R K = ±0.0% (stat) ± 0.15% (syst) = ±0.5% stopped K beam; complementary to in-flight exp. 11

12 Search for heavy sterile neutrino, M N < M K Add to the SM! three right-handed sterile neutrinos with masses roughly of the order of masses of known quarks and leptons.! to handle in an economic and unified way the problems of! dark matter (N 1 ), neutrino masses (N and N 3 ), baryon asymmetry of the universe (N and N 3 ) mass charge ⅔ name Quarks Leptons I II III.4 umev 1.7 cgev ⅔ up charm Right Right Right 4.8 dmev 4 -⅓ smev -⅓ down strange ν e Three Generations of Matter (Fermions) spin ½ μ Right Right Right 171. tgev ⅔ top 4. bgev -⅓ bottom τ Right Right N ν electron 1 N ν muon N tau sterile neutrino neutrino sterile neutrino sterile 3 neutrino neutrino neutrino emev μmev τgev electron muon tau Right Bosons (Forces) spin 1 K + µ + N g gluon γ photon 91. GeV Z 0 0 weak force 80.4 GeV W ± ± 1 weak force SM minimal extension in neutrino sector H >114 GeV 0 0 Higgs boson spin 0 M(N 1 ) 1 kev M(N ) M(N 3 ) 0 MeV S.N. Gninenko, D.S. Gorbunov, M.E. Shaposhnikov, Advances in High Energy Physics 01, ID (01) Neutral heavy lepton production Fig. from Vaitaitis et al., Phys. Rev. Lett. 83, 4943 (1999). 1

13 Search for sterile neutrinos in the Kaon weak decay with TREK Early Monte Carlo Simulation K + µ + N,3 50 K + e + N,3 counts/bin strongly suppressed Kμ3 background with photon / π 0 veto heavier µ + momentum (MeV/c) lighter m N 00 MeV/c TREK E36 Present E36 run plan with limited muon statistics (suppressed in trigger); trigger and acceptance optimized for K e decays. Background from radiative channels (Kμ3, Ke3, Kμγ, Keγ, ) requires hermetic photon veto. Dedicated running with changed setup needed for adequate sterileneutrino search. Signal: Peak in µ + or e + momentum distribution from two-body decay of K +. 13

14 The proton radius puzzle: Muonic and electronic measurements give different proton radii The discrepancy between muonic and electronic measurements of the proton radius is a 7σ effect. Spectroscopy Scattering r p = (67) fm r p = 0.875() fm r p = (69) fm r p = (39) fm I. Sick, PLB 576, 6 (003); P.J. Mohr et al., Rev. Mod. Phys. 80, 633 (008); J.C Bernauer et al., PRL 5, 4001 (0); R. Pohl et al., Nature 466, 13 (0); X. Zhan et al., PLB 705, 59 (011); P.J. Mohr et al., Rev. Mod. Phys. 84, 157 (01); A. Antognini et al., Science 339, 417 (013) Possible explanations of the proton-radius puzzle Electron scattering & atomic hydrogen data and radius extraction not as accurate as previously reported. Novel Hadronic Physics: Strong-interaction effect entering in a loop diagram is important for µp but not for ep. Beyond Standard Model Physics: Violation of µ - e universality 14

15 Search for dark light Explore U(1) extension of the Standard Model with photon-like massive gauge boson A. Motivation: Explain anomalies in astrophysics and particle physics, proton radius puzzle,... K + µ + νa' A' e + e Constrain dark photon parameter space with rare kaon-decay data. QED background full phase-space value of: J. Bijnens, G. Ecker, and J. Gasser, Nucl. Phys. B396, 81 (1993) Γ(K + µ + νe + e ).5 5 e K γ e e γ e γ e e dark photon, A replaces photon, γ (weak coupling) 15

16 Simulation for E36 gauge boson search Anticipated kaon decays. Full reconstruction of the µ + νe + e - final state. K + µ + νa' µ + νe + e Counts Simulated Reconstructed events: Invariant Δp/p Mass = 5%, e+e- Δθ = 4 M A ' M e - [ MeV/c ] + e # background events Background distribution AFTER ALL cuts M e - [ MeV/c ] + e Signal: Peak in M(e + e - ) spectrum measured in the CsI(Tl) calorimeter. Smooth, predictable background from QED processes. Simulation: P. Monaghan, HU/CNU (014) 16

17 A parameter space exclusion limits (universal coupling) Mixing Parameter E36 limited acceptance recent progress by JLab, MAMI, KLOE, BaBar g- KLOE APEX Mainz.5e11 kaons: BEFORE cuts.5e11 kaons: AFTER cuts m A' BaBar [ MeV ] K + µ + νa' µ + νe + e K + π + A' π + e + e Full reconstruction of the µ + νe + e - and π + e + e - final states.! Under the assumption of universal coupling E36 result will be mostly complementary to previous data. Estimate from P. Monaghan HU/CNU 17

18 Constraints to new physics models for the proton charge radius puzzle from the decay K + μ + νe - e + An explanation of the proton-radius puzzle involving new particles must include larger couplings to muons than electrons (the interactions must violate lepton universality). Dark photon contribution (Kinetic mixing only) Batell et al. modified dark photon contribution (additional direct coupling to right-handed muons) d K ee MeV dmee m ee tot K QED background bin width 1 MeV mass 30 MeV N m ee MeV d K ee MeV dmee m ee tot K bin width 1 MeV mass 50 MeV g R 0.05 N 3 QED background m ee MeV C.E. Carlson and B.C. Rislow, Phys. Rev. D 89, (014) B. Batell, D. McKeen, and M. Pospelov, Phys. Rev. Lett. 7, (011) 18

19 Constraints to new physics models for the proton charge radius puzzle from the decay K + μ + νe - e + Carlson & Rislow modified dark photon contribution (New particles with polar-axial vector or scalar-pseudoscalar couplings to muons and protons. d K ee MeV IB only dmee m ee tot K QED background bin width 1 MeV N 3 Polar Axial d K ee MeV IB Only dmee m ee tot K QED background bin width 1 MeV N 3 Scal Pseudo m ee MeV m ee MeV TREK E36 can rule out any new physics explanation of the proton radius puzzle involving light bosons with preferred couplings to muons. C.E. Carlson and B.C. Rislow, Phys. Rev. D 89, (014) 19

20 E46 apparatus is being upgraded by the TREK collaboration to search for new physics in the decay of stopped kaons at J-PARC. E06 Search for T violation in kaon decays K + π 0 µ + ν µ transverse muon polarization E36 (partial upgrade) Search for lepton universality violation in a measurement of the ratio of the K widths Search for a heavy sterile neutrino Search for lepton flavor violating contributions in dark light K + e + ν(γ ) K + µ + ν(γ ) K + e + N K + µ + N K + µ + νa' µ + νe + e K + π + A' π + e + e R K decay-width ratio peaks in lepton momentum distributions peaks in M(e + e - ) or π + momentum distributions E36: detector construction & installation until December 014, engineering run January and February 015, physics run March-June 015 E06: when higher beam power is available at J-PARC 0