T. Lesiak. The SuperB project

Transcription

1 The SuperB Project Tadeusz Lesiak Institute t of Nuclear Physics PAS, Cracow & Cracow University of Technology

2 B-factories tremendous physics 2

3 B physics at the (4S) e + e - collisions i at E CMS M( (4S)) the cleanest way to produce B mesons 3

4 B factories: the 1st generation Plenty of rare decays of B mesons a very large statistics of B mesons is a must CP violation measurements = (often) time dependent asymmetries beam energies are asymmetric too (to boost the B mesons in the LAB frame) 4

5 B physics is clean x-y projection y-z 5

6 Exciting results every year! Achievements at B-factories 2008 Nobel Prize Kobayashi & Maskawa τ decays: limits on LFV (5S) (D s ) physics Evidence for D 0 mixing i Observation of B D * τν τ Observation of direct CPV in B Evidence for B Observation of b d FB asymmetry in B K* l + l - Evidence for direct CPV in B K + Discovery of X(3872) Hint at new physics: CPV in B K s Observation of B K (*) l + l Observation of CPV in B meson system 6

7 B factories (Super) Flavour Factories GENERATION ONE GENERATION TWO Expectations from the Super Flavor Factories 7

8 SuperB vs LHC LHC energy frontier potential for discoveries e.g. peaks of new particles 2nd generation of B-factories: flavour physics a precise tool (virtual loops, rare or forbidden processes) Both QUARK (b,c) and LEPTON (tau) sectors to be probed Tau physics particularly exciting (CPV, LFV, EDM, g-2, ) Connections with astroparticle physics The complementarity m with the LHCb physics program 8

9 SuperB: main Physics goals (In descending order of masses of heavy flavour particles) (4S): improvement by an order of magnitude High in the precision (to compare with BaBar and Belle) luminosity needed 2. Tests of the CKM paradigm at the 1% level 3. Potential spectroscopy discoveries 4. b physics at Upsilon resonances other than (4S) Scan in CM energy 5. CPV in charm, also with time dependent asymmetries 6. Tau physics LFV sensitivity improvement by one-two orders of magnitude CP and T-violation Magnetic structure ofthe tau Longitudinal polarization of the electron beam 9

10 CKM precision measurements η 1ab 1 η 75ab 1 ρ ρ =0.028 ρ = η = η = ρ 10

11 B Y(4S) (from A.Bevan DESY sem). Variety of measurements for any observable Possible also at LHCb Similar precision at LHCb Example of «SuperB specifics» inclusive in addition to exclusive analyses channels with s many Ks 11

12 Lepton Flavour Violation (LFV) in tau decay The tau is the most suitable lepton to search for LFV effects (the heaviest charged lepton with many possible LFV decay modes) LFV for charged lepton is negligibly small in the SM (even after taking into account neutrino oscillations) B(τ lγ) < B(τ lll) < LFV decays occur in many extensions n of the SM e.g. SUSY their branching fractions could be enhanced to the level as high as the experimental sensitivity of the SuperB 12

13 LFV in tau decay LHC(b) SuperB (off the scale) The sensitivity of SuperB is times below overall predictions of New Physics e.g. B(τ μγ) ) B(τ μμμ) ) To compare with current limits: > (BaBar) > (Belle) Other SuperB speciific channels: τ lh, τ hγ, h = π 0, η (0),K 0 S,... 13

14 CPV in tau decay CP violation in charged lepton decays no observation yet The SM: CP violating asymmetries are expected to be vanishingly small e.g. A CP = Γ(τ + K + π 0 ν τ ) Γ(τ K π 0 ν τ ) Γ(τ + K + π 0 ν τ )+Γ(τ K π 0 ν τ ) o(10 12 ) only in a few NP frameworks (RPV SUSY, non-susy multi-higgs models) the CPV asymmetries in angular distributions can be enhanced even up to o(10-1 ); sizeable effects for τ Kπν τ, τ Kη (0) ν τ, τ Kππν τ CLEO : study of tau charge-dependent d asymmetry of the angular distribution of the hadronic system produced in τ Ks 0 πν τ (also for τ ππν τ ) CLEO estimate (13.3 fb -1 ): SuperB sensitivity (75 ab -1 ): ξ(τ K 0 s πν τ )=( 2.0 ± 1.8) 10 3 ξ the mean of the optimal asymmetry observable ξ(τ K 0 s πν τ )

15 Measurement of the tau g-2 Long standing discrepancy for the muon g-2: a μ = a exp μ a SM μ (3 ± 1) 10 9 The natural scaling: a μ a τ m 2 m τ 2 μ interpreting the as a signal of NP a μ a τ 10 6 The tau g-2 (as the tau EDM) influences both the angular distributions and the polarization of the tau produced in e+e - annihilation SuperB (75 ab -1 ): can measure both the real and imaginary part of the g-2 form factor with the resolution of ( ) 10 6 Proposed measurements : 1. Fit to the polar angle distribution of the tau lepton 2. Measurement of the transverse and longitudinal l polarization of the tau from tha angular distribution of its decay products Crucial role of beam polarization similar considerations for the electric dipole moment (EDM) of the tau 15

16 LFV in tau decays B(τ μγ) UL can be correlated with B(μ eγ) UL 1. (MEG experiment) 2. Θ 13 (neutrino mixing/cpv) SUSY seasaw = CMSSM + 3 R + Herreo et al Plot for three reference values of the heavy right-handed neutrino mass (m N3 ) and several values of Θ 13 MEG (now) MEG (design) SuperB 16

17 B s at (5S) B s -related measurements domain of the LHCb (and ATLAS and CMS) BUT: short runs at the (5S) (CLEO, Belle) indicated the potential for e+e - machines to contribute in this area Potential highlights from the SuperB: 1. B s decays involving neutral particles: B s J/ψη B s D ( ) φ B s J/ψη 0 B s D s ( )+ D s ( ) B s D ( ) K 0 S B B 0 s φη π 0 s J/ψKS 0 B s KS 0π0 (from A.Bevan DESY sem.) 2. Measurement of B(B s γγ) SM: Br (2-8) 10-7, NP (e.g. SUSY) SuperB precision (30 ab -1 ) 7% (stat), 5% (syst) (assuming the Br of the SM) 3. Measurement of the semileptonic asymmetry of the B s : SuperB precision (30 ab -1 ): A s SL = 1 q p 4 1+ q 4 = N 1 N 2 N 1 +N 2 N 1 = B(B s B s D ( ) s l + ν l ) N 2 = B(B s B s D ( )+ s l ν l ) p 17

18 Charm SuperB: plans for running at DD threshold Possible scenario: 500 fb -1 at the ψ(3770) ( ) few months of running (10 35 cm -2 s -1 ) For charm physics equivalent of at least 100 times integrated luminosity at the (4S) DD pair is entagled: tagging events in which h one D meson is identified the other D can be studied with very small background contamination (from A.Bevan DESY sem.) Potential highlights from the SuperB: 1. Improved precision in mixing parameters x D and y D 2. Measurement of the asymmetry α SL 3. Search for D 0 μ + μ - 4. Quantum correlations in decays od D s canallow for measurement of their relative strong phases 18

19 B factories: a plethora of new states Spectroscopy Most of them do not fit into conventional mesons and baryons hybrid mesons, molecules, tetraquarks cc All the new states (apart from the X(3872) ) have been observed in only a single decay channel, each with a significance barely above 5σ SuperB: x100 more events much more detailed studies of these states, also in several other modes Natural expectations of new discoveries at the SuperB Bottomonium: SuperB can look for not yet observed singlet states (parabottomonia) Other players (both for charm and spectroscopy): LHCb, BESIII and PANDA (FAIR) 19

20 The Accelerator and Detector 20

21 The Quest for Luminosity Luminosity cm -2 s -1 KEKB cm -2 s -1 SuperB L = γ µ ± 2er e Lorentz factor µ 1+ σ y σx Beam current 1.7/1.4 A e+e - KEKB 19/25AS 1.9/2.5 SuperB I± ξ y± β y± R Beam-beam parameter 0.09 KEKB SuperB Geometrical reduction factor Classical electron radius Moderate beam requirements 1.9/2.5 A beam current moderate RF power (17 MW) 5 mm bunch length (σ z ) Low emittance: ² * x ² * y = 2 nm 5 pm continuous injection Beam aspect ratio at IP All of these have been done at other facilities * - beta-function %(fl (flat tb beam) (trajectories envelope) atip 6.5/5.9 mm KEKB 0.3 mm SuperB Tight focus at the IP σ x * σ y * = 8 μm µm smaller than done so far 21

22 IP beam distributions for KEKB Beam envelopes: KEKB vs SuperB KEKB SuperB IP beam distributions for SuperB I(A) y * (mm) x * (mm) y * ( m) x * ( m) z (mm) 6 5 L(cm -2 s -1 ) 17x10 1.7x x10 36 Here is Luminosity ygain 22

23 The crab waist x e+ x Y e- 2 z * z 2 z 2 x y x z 23

24 The crab waist x Crabbing off e+ Crabbing on x Y e- 2 z * z z 2 z 2 x Realization: sextupole & anti-sextupole y Luminosity improvement by a factor 2-4 on both sides of the IR x z Positive tests at DAΦNE 24

25 Suppression of Synchro- Beta Resonances Example NOcrab waist crab waist ON ν y Tune scan (Ohmi) ν x ν x mν x + nν y 6= l, m, n, l =0, ±1, ±2,... 25

26 Polarization The electron beam (HER) will be longitudinally ll polarized (80%) the unique feature of the SuperB The polarized e - source (similar to SLAC SLC source) transverse polarization Spin rotators (solenoids) placed before and after IP longitudinal polarization The polarization would play a crucial role in several measurements e.g. precise determination ti of sin 2 Θ W, g-2, tau EDM, LFV processes e + e μ + μ A = (σ F σ B ) L (σ F σ B ) R LRF B (σ 2 F +σ B ) L +(σ F +σ B ) R < P e > sin Θ W ( + ) +( + ) 1 < P > Polarisation additional discriminating variable to LFV searches background suppression: τ μγ Signal (with polarization) Triangular distribution signal (with polarisation) si in 2 Θ W SuperB Background Background (sin 2 θ W ) similar to LEP. Q [GeV] cos Θ hel μ 26

27 SuperB vs SuperKEKB ² y ² x β y β x σ z e - polarization 80% none Run at ψ(3770) yes no 27

28 Where to dig the tunnel? SuperB on the LNF site (Frascati) Collider hall Damping ring 28

29 Where to dig the tunnel? SuperB on Tor Vergata site SPARX FEL SuperB Ring ( circumference 1800m) SuperB Injector (~ 400m) 100m Roman Villa SuperB Main Building 29

30 Where to dig the tunnel? SuperB on the LNF site 30

31 SuperB detector βγ =0.28 Some components of BaBar s experiment will be reused 31

32 The silicon Vertex Detector t (SVT) Layers 1-5: Strips or Pixels Layer 0: Striplets or Pixels Beam pipe radius cm Beam pipe material 0.5 % X 0 Layer 0radius cm 32

33 The Drift Chamber (DCH) Work on optiimisation of the design: geometry, cell size, gas mixture Composition: 40 layers of cm-sized cells strung parallel to the beam line cells The occupancy: 3.5% (5% inner layers) The baseline design with spherical endcaps (carbon fibres) The measurement of momenta of slow particles (p < 700 MeV/c) 33

34 The Cherenkov Detector Based on the concept of DIRC (Detector of Internally Reflected Cherenkov light) Momentum range: GeV/c The radiator: synthetic fused silica 34

35 SuperB Collaboration The regular meetings of the collaboration, organized every three months, gather 130 participants In the full swing, the collaboration would be composed of members 35

36 SuperB Collaboration Organization chart 36

37 On the way to approval The progress in Italy - support from the INFN - the first position among flagship projects in Italian National Research Plan project located in the Roadmap for Research Infrastructure t - expectations for formal approval and decision about by Italian government in 2010 The progress in Europe - support from ECFA and the CERN Council - plans for applications for UE funds: ERIC (European Research Infrastructure Consortium) and TIARA (Test Infrastructure and Accelerator Research Area) Support from USA, UK, Canada Interactions with SuperKEKB project 37

38 References A Conceptual Design Report (CDR), signed by 85 Institutions was published in March 2007 (arxiv: [hep-ex]) White Papers (on accelerator/detector/physics) are almost ready The work on the Technical Design Report (TDR) will start soon See the web page: 38

39 Summary New era: B-factories Super Flavour Factories The Super Flavour Factory SuperB aims to be a precise tool to elucidate New Physics in a way competitive to the LHC To achieve this goal, the reach of luminosity cm -2 s -1 and the total sample of 75 ab -1 is expected The SuperB offers two unique features: the polarization of e - beam (vital for tau physics) possibility of scan in CM energy (vital for charm physics) 39

40 T.Lesiak SuperB 40