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The Physics of Super B - Experimental

The Physics of Super B - Experimental Detector requirements and physics performance required to achieve the physics goals. David Hitlin INFN Super B Review November 12, 2007. This talk will primarily address two topics:

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The Physics of Super B - Experimental

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  1. The Physics of SuperB - Experimental Detector requirements and physics performancerequired to achieve the physics goals David Hitlin INFN SuperB Review November 12, 2007

  2. This talk will primarily address two topics: • Design considerations for an appropriate detector for a 1036 collider like SuperB • Note that detector technology issues for SuperB, a low-emittance, low current collider, are quite different from those for a high current machine such as SuperKEKB • The physics goals are also different from those of BABAR/Belle • How can we upgrade an existing detector (using BABARas an example) to better match the new physics goals ? • With such an upgraded detector, can we reach adequate levels of sensitivity to be relevant to the elucidation of the details the flavour sector of any new physics found at the LHC ? David Hitlin INFN SuperB Review Nov. 12, 2007

  3. Primary physics objectives of a Super Flavour Factory Are there new CP-violating phases ? Are there new right-handed currents ? Are there new loop contributions to flavour-changing neutral currents Are there new Higgs fields ? Is there lepton flavour violation ? Is there new flavour symmetry that elucidates the CKM hierarchy ? What are the requirements for a detectorthat can address these questions in a 1036 asymmetric e+e- environment ? David Hitlin INFN SuperB Review Nov. 12, 2007

  4. Doing the physics: environment and event characteristics The primary physics goals of SuperB differ from those of BABAR and Belle, which showed that the CKM phase is consistent with all known CP-violating phenomena and that the Unitarity Triangle could withstand a detailed series of over-constrained tests The SuperB physics goals are the next logical step, using rare heavy flavour decay phenomena as a sensitive probe of physics beyond the Standard Model The basic physics environment (e+e- annihilation from GeV) is familiar, but the physics objectives differ, and the luminosity of SuperB is increased by nearly two orders of magnitude over the current machines Thus the background environment is different and the trigger requirements differ from those of PEP-II/KEKB In what way do these differences reflect into the design of the SuperB detector? This talk will review the machine-produced environment and event characteristics and use several specific physics examples to arrive at a set of design criteria for the SuperB detector Specific design details will be presented in the following talks David Hitlin INFN SuperB Review Nov. 12, 2007

  5. Trigger rates and DAQ Physics rate at 1036 are substantial Due to the low emittance design, machine backgrounds appear to be tolerable and a small radius beam pipe is feasible, allowing use of a reduced energy asymmetry Physics demands an open trigger as is traditional in e+e- Demands on the trigger and DAQ are thus substantial, but LHC-derived technologies are sufficient Further details in later presentations David Hitlin INFN SuperB Review Nov. 12, 2007

  6. Choice of energy asymmetry 7x 4 GeV Boost bg=.28 PEP-II: bg =0.56 Smaller SuperB beam sizes at the IP allow the use of a smallerbeam pipe (radius 1 cm) This permits a thinner beam pipe in radiation lengths First track measurement at 1.2 cm Smaller asymmetry improves solid angle coverage David Hitlin INFN SuperB Review Nov. 12, 2007

  7. David Hitlin INFN SuperB Review Nov. 12, 2007

  8. Solid angle coverage 7x4 GeV Solid angle(% of 4p) D (%) 7x4 vs 8x3.5 GeV 800 700 200 600 300 500 400 400 500 300 600 200 700 800 Rear coverage (mrad) Forward coverage (mrad) Coverage of BABAR: 300 mrad forward 600-700 mrad backward David Hitlin INFN SuperB Review Nov. 12, 2007

  9. Final state reconstruction efficiency In B meson decay <nch>=5, <ng>=5 t decay is dominated by 1 and 3 prong topologies We expect recoil physics to be an important part of the program Both B mesons must, perforce, be reconstructed In most, but not all cases, the object of photon detection is p0 reconstruction. Thus ~ eg2 The effective solid angle for complete final state reconstruction is determined by the system which has the minimum solid angle coverage evertexetrackingePIDeg David Hitlin INFN SuperB Review Nov. 12, 2007

  10. B0fKs reco efficiency vs solid angle coverage J. Back David Hitlin INFN SuperB Review Nov. 12, 2007

  11. Track momenta and polar angle distribution David Hitlin INFN SuperB Review Nov. 12, 2007

  12. Track momenta at lower Ecmare substantially softer SuperBcan run at lower Ecmfor specific D and t studies,as well as at the other U resonances (particularly U (5S) ) (with bg=0.28) 1 month of SuperB running at y(3770) or for below charmcharm threshold yields 10Xfinal BES-II data David Hitlin INFN SuperB Review Nov. 12, 2007

  13. Center-of-mass energy spread PEP-II, SuperB (4S) Many analyses use cuts onm ES and DE to extract a signal Center-of-mass energy spread determines m ESand thus thesignal-to-noise ratio in rare B decays Center-of -mass energy spreadalso determines the effective cross section on the U(4S) , U(5S) or y(3770) resonances This was a concern in earlier incarnations of SuperB whichhad highly disruptive collisionsbut is no longer an issue David Hitlin INFN SuperB Review Nov. 12, 2007

  14. DE resolution p+p- D*p David Hitlin INFN SuperB Review Nov. 12, 2007

  15. p Brecoil e- D* n Breco e+ Xu Recoil physics at the¡(4S) • “The Recoil Method “ will beof increasing importance at SuperB • Fully reconstruct one of the twoB’s in hadronic modes and/or semileptonic modes as well .......and do it with high efficiency • The rest of the event is the otherB, whose four-momentum is known • You then have a single Bbeam: • reduced backgrounds for rare decay studies, especially those with neutrinos, and • reduced systematics forprecision Vcb, Vubstudies • Semileptonic decays • B D(*)n, B (p,r)n, BXc,un • B D(*)tn (sensitive to New Physics) • Purely leptonic decays Btn, …. • B Knn • Binvisible • B Xsg David Hitlin INFN SuperB Review Nov. 12, 2007

  16. Xcn Xun sg Dtn p+n p0n tn Knn p+tn • 10-2 10-1 1 10 • Luminosity (ab-1) The recoil method • Subtract combinatorial background • Breco (recoil) kinematics known with small uncertainties • Breco(recoil) flavor determined • Breco(recoil) charge (B0- B+separation) • DirectmXreconstruction • Lepton charge – Breco(recoil) flavor correlation • Kinematic constraints on recoil B • Low efficiency - can be tuned for purity purity yield Reconstructed B mesons Number of recoil events 0 2 4 6 8 10 Luminosity (ab-1) David Hitlin INFN SuperB Review Nov. 12, 2007

  17. Acceptance studies BKGD/Signal with smearing Forward polar angle coverage (radians) BKGD/Signal with smearing Backward polar angle coverage (radians) M. Mazur • Many of the main physics objectives of SuperB involve missing energy signatures • Detector requirements • Use of the recoil technique • Excellent reconstruction efficiency for hadronicB decays, especially those involving D*s • Excellent particle ID • Hermeticity • Improving backward calorimeter coverage can pay large dividends in signal/background • Study using Btn benchmark David Hitlin INFN SuperB Review Nov. 12, 2007

  18. Signal decay LFV: no pmiss CM frame SM t decay (1- or 3- prong) (1 or 2 ) LFV in t decays: SuperB capability tg :the ultimate sensitivity will be affected by e+e-t+t-g t+tagt- m-nngirreducible background. When that limit is reached, the sensitivity scales as 1/sqrt(L). For ~75/ab(SuperB @ 5 yrs) expect ~2x10-9 • (MEC) ~9MeV  (E) ~50MeV David Hitlin INFN SuperB Review Nov. 12, 2007

  19. LFV in t decays: SuperB capability t , hh’ : the sensitivity is not likely to be limited by irreducible backgrounds:the sensitivity scales as 1/L. For SuperB @ 5 yrs expect ~2x10-10 Principalbackgrounds David Hitlin INFN SuperB Review Nov. 12, 2007

  20. LFV in t decays: SuperB capability SuperB sensitivity directly confronts many New Physics models BABAR SuperBsensitivity For 75 ab-1 David Hitlin INFN SuperB Review Nov. 12, 2007

  21. Limits are highly constraining (example tmg) David Hitlin INFN SuperB Review Nov. 12, 2007

  22. Comparison to Snowmass Points and Slopes SPS-4 • Argand and Herrero arXiv:0710.4091v1 [hep-ph] • Lepton Flavour Violation in SUSY-seesaw: an update • MSSM + three right-handed neutrinos + SUSY partners David Hitlin INFN SuperB Review Nov. 12, 2007

  23. t lll- LFV chiral couplings SuperB sensitivity to t lllis an order of magnitude betterthan for t  mg: 2x10-10 Models predict a wide range of B(t lll )/B(t  mg ): If t lll is seen, it can, using polarized t’s, also be the key to studying the chiral couplings of the LFV physics David Hitlin INFN SuperB Review Nov. 12, 2007

  24. Polarized t’s can probe the chiral structure of LFV (lll) Flipping the helicity of theelectron beam allows us to ascertain the chiral structureof dimension 6 four fermionlepton flavor-violating interactions Dassinger, Mannell, et al. David Hitlin INFN SuperB Review Nov. 12, 2007 24

  25. Polarization Luminosityenhancement tpolarization • Longitudinally polarizing one or both beams allows a sensitive search for Tviolation in t production and/or CP violation in t decay • Seeing either of these phenomena is a longshot, but one with a substantial payoff • Longitudinal polarization of the electron beam is straightforward (was routine in SLC operation) • Longitudinal polarization of the positron beam is an R&D project David Hitlin INFN SuperB Review Nov. 12, 2007

  26. The SuperB design has a longitudinally polarized e-beam • Several techniques of achieving longitudinal e- polarization of >80% at the IP are discussed in the CDR (see later presentation) • Provides polarization in the 10 GeV CM region, not at lower ECM • Production of polarized positrons (~40%) is a substantial R&D project, and in fact, a potential area of synergy with ILC R&D • SuperB plans only a polarized e-, which yields most of the physics benefits David Hitlin INFN SuperB Review Nov. 12, 2007

  27. CP violation in t production and a t EDM where Bernabeu et al. A three order of magnitude improvement over current bounds With a polarized electron beam, can define an azimuthal asymmetry in hadronic t decays sensitive to to a t EDM : Summing over t+ and t- yields a true CP-odd observable Sensitivity: David Hitlin INFN SuperB Review Nov. 12, 2007

  28. CPViolation in t decay • Unpolarized t’s • Measure B’s of t decays with two or more hadronsInterpretation of any observed CPV requires understanding of inelastic final state interactions • Measure CP or T-violating correlations in t+t- decays • Polarized t’s • Search for T-odd rotationally invariant products, e.g. in t+ and t- decays such as • Search for T-odd correlation between t polarization and m polarization in decay • Sensitivity to asymmetries at the 10-3 level David Hitlin INFN SuperB Review Nov. 12, 2007

  29. (Data/MC) inefficiency (%) Polar Angle q (radians) Tau magnetic dipole moment • The polar angle distribution of t’s is sensitive to the t magnetic dipole moment • It is necessary to understand thereconstruction efficiency as a functionof polar angle to the 10-3 level by use of a control sample • This level of understanding can already be demonstrated with in BABAR data: J.Bernabeu et.alhep-ph 0707.2496 BABAR 75 With polarized e-, it ispossible to separate theanomalous moment ff from the charge ff Preliminary BABAR Reconstruction inefficiency (~1%) measurable with a 10% uncertainty Goals are achievable David Hitlin INFN SuperB Review Nov. 12, 2007

  30. Extrapolated statistical errors on CPasymmetries BABAR measurement errors 50 ab-1 Currentprecision David Hitlin INFN SuperB Review Nov. 12, 2007

  31. BgfK0 at 50/abwith present WA value J/yK0 fK0 David Hitlin INFN SuperB Review Nov. 12, 2007

  32. Conclusions • An excellent detector for SuperB can be constructed using an existing detector such as BABAR as a base • Improved hermiticity is of prime importance, as is improved vertex detection, better muon ID, a much higher bandwidth DAQ system, and an improved trigger • A polarized electron beam enables t EDM, CPV and anomalous moment measurements • Polarization experiments impose no new requirements on the detector • In fact, systematics due to detector inhomogeneity are reduced • There is, of course, overlap with the programs of LHC flavour experiments such as LHCb, but the e+e- environment makes possible a substantial number of unique and important physics objectives, especially in those areas most sensitive to new physics, such as LFV, FCNC, decays involving (multi) neutrals, mixing, ….. • The achievable levels of sensitivity in rare Band t decays allow substantial coverage in the parameter space of new physics • High statistics flavour physics at an e+e- collider will likely provide information crucial to the understanding of new physics found at LHC David Hitlin INFN SuperB Review Nov. 12, 2007

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