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David Hitlin Caltech March 20, 2003

Physics and Detector Challenges. at a. Super Factory. B. David Hitlin Caltech March 20, 2003. Parsing the title of the talk. Physics Challenges

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David Hitlin Caltech March 20, 2003

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  1. Physics and Detector Challenges at a Super Factory B David Hitlin Caltech March 20, 2003 D. Hitlin SLAC B-Day

  2. Parsing the title of the talk • Physics Challenges • The improvement of measurement precision is a sufficient motivation for a 1036 machine, if and only if the improved precision takes us into discovery territory • There are indeed areas in which large data samples (10-50 ab-1) can lead, with reasonable certainty, to measurable new physics effects, by increasing precision or making certain measurements possible • The context is also important • What new physics potential exists with a 10-50 ab-1 sample that doesn’t exist with a 0.5-1 ab-1 sample? • What can an asymmetric e+e- machine at 1036 contribute beyond what can be done at hadron experiments (ATLAS, CMS, LHCb,BTeV)? • What is the time window for 1036? • Detector Challenges • What do we need in a detector to do physics at a 1036 machine? • Should there be an upgrade of BABAR, or a totally new detector? • What R&D is required on new detector subsystems? D. Hitlin SLAC B-Day

  3. The New Physics Bible according to Nir • CP violation is an excellent probe of new physics • The Standard Model CKM mechanism has a single source of CPV and makes quantitative predictions • New sources of flavor and CP violation can induce large deviations from the Standard Model predictions, many of which are not obscured by hadronic uncertainties • Henceforth in this discussion, I will emphasize thesupersymmetric Standard Model as an example, although other extensions of the Standard Model can also produce observable effects • The supersymmetric SM has 124 independent parameters, 44 of which are CP-violating • What are the constraints of existing measurements of CPV on SUSY model building? • What are the prospects that future CPV measurements will uncover deviations from the SM predictions? • Having found that ACP in agrees with CKM prediction, we are beyond the era of seeking alternatives to the CKM phase and must now search for new physics by finding loopcorrections to the CKM picture D. Hitlin SLAC B-Day

  4. New CP Violating effects must be there • CP effects in the flavor sector that are not accounted for by the CKM phase must exist • If they do not exist, SUSY and other models constructed with the same motivation will be ruled out • The sensitivity required to see these effects can be reached • It is possible, though not likely, that SUSY could be discovered through loop effects before there is explicit production of new particles at LHC • Assume that evidence for SUSY is found at the LHC or NLC • What will we actually know? • The masses of some of the SUSY partners: gluino, squark, …….. • Something about coupling constants • Perhaps the identity of the LSP • Even if the first evidence for SUSY comes from LHC, it will be important to study CPVin flavor physics at the scale of 1010 to 1011B decays D. Hitlin SLAC B-Day

  5. SUSY mass spectra for the 9 Snowmass points & slopes 1500 1000 500 250 SPS-4 SPS-1 SPS-9 SPS-7 SPS-8 SPS-2 SPS-3 SPS-6 SPS-5 Ghodbane and Martyn D. Hitlin SLAC B-Day

  6. Many SM extensions yield measurable effects in B physics Generic Little Higgs Little Higgs wMFV UV fix Generic extra dim w SM in bulk Extra dim wSM on brane SUSY GUTs SupersoftSUSY breakingDirac gauginos MSSMMFVlarge tanb MSSMMFVlow tanb Effective SUSY SM-like B physics New Physics in B data after G. Hiller D. Hitlin SLAC B-Day

  7. Mapping SUSY-breaking schemes to flavor models Exact Universality MSUGRA Approximate Universality GMSB No Universality Approximate CP AMSB MFV ĞMSB Extended MFV SUSY GUTS       J. Hewett D. Hitlin SLAC B-Day

  8. Constraints on SUSY from existing measurements • In order to obey the constraints from K decay: • Indirect CPV in and decays: |e| = (2.28  0.02) x 10-3 • Direct CPV in decays: Re|e/e|=(1.66  0.16) x 10-3 • it is necessary to invoke one or more of the following: • Heavy squarks: • Universality: • Alignment: • ApproximateCP: CPV phases are small • All viable models of SUSY-breaking use one or more of these mechanisms • Two other measurements: • ACPin decay: Im lK = 0.734  0.054 • Limits on EDM’s (through T violation and CPT) impose serious additional constraints • For example, ACP effectively kills Approximate CP models • EDM limits imply that the source of CPV beyond the Standard Model in models with minimal flavor violation is Yukawa couplings, which can be flavor dependent D. Hitlin SLAC B-Day

  9. Effects of SUSY breaking on CPV in flavor physics • Specific models produce specificCPV patterns • There are a variety of models of SUSY breaking on the market • Many of these models generate specific, calculable CP-violating effects in hadronic and rare B decays • Other extensions (extra dimensions, Little Higgs,….) have the same sorts of effects, although they often have distinguishable patterns • In order to exploit CP violation as a tool to search for physics beyond the Standard Model we must do two things: • Achieve the highest meaningful precision on CPV (a, b, g ) measurements of the B unitarity triangle • This requires several x 10 ab-1 • Measure kinematic distributions and CP-violating (and sometimes CP-conserving) asymmetries in very rare decays with branching fractions of <10-5, both inclusive and exclusive • These are decay modes such as where we have at present only a handful of events D. Hitlin SLAC B-Day

  10. Probes of new physics - I • Measure the CP asymmetry in modes other than that measure sin2b in the Standard Model • Precision of benchmark sin2b in can improve to the 1% level • Expect the same value for “sin2b ” in“ ,but different SUSY models can produce different asymmetries • A great deal of luminosity is required to make these measurements to meaningful precision D. Hitlin SLAC B-Day

  11. From the BABAR Physics Book (SLAC‑R‑504) D. Hitlin SLAC B-Day

  12. Variations from SM predictions can be substantial • Three examples • mSUGRA • SU(5) SUSY GUT with nR • U(2) Goto, et al. D. Hitlin SLAC B-Day

  13. r250 r500 rSM Many CP asymmetries can be changed by SUSY Ciuchini, Franco, Martinelli, Masiero, & Silvestrini D. Hitlin SLAC B-Day

  14. SUSY models are already constrained by ACP, Dm, EDM U(2) model of Masiero, et al.There are two real parameters, j andy  j = -0.25, y = 0  j = -0.25, y= -0.25 x j = -0.5, y= -0.25 D. Hitlin SLAC B-Day

  15. Other Standard Model extensions also change CPV Grossman and Worah D. Hitlin SLAC B-Day

  16. An example: CP in • The fact that the CP asymmetry in is so close to theStandard Model prediction tells us that new CP-violating contributions to bdtransitions (via ) are small • The fact that is close to the Standard Model value tells us that the helicity-conserving part of is small. • The helicity-changing part of , i.e., and could still be large • and enter the supersymmetric gluonic penguin that contributes to • This produces a series ofinter-related constraints: Chang, Masiero, Murayama: Change in B(bsg) ACPfKS Dms D. Hitlin SLAC B-Day

  17. BABARfKS results Ncand = 66 Purity = 50% 81.3 fb-1 D. Hitlin SLAC B-Day

  18. Pure CKM forbidden penguin amplitude Current ACP(fKs) has large errors, but opposite sign Interesting, but not yet a persuasive case for new physics D. Hitlin SLAC B-Day

  19. CP violation in modes that measure “sin2b”” It is certainly premature to draw any conclusions about disparities. One mode is clean: fKS. Branching ratio is small. Could a statistically persuasive case for a different ACP from J/yKS be made? D. Hitlin SLAC B-Day

  20. What level of precision is required ? • Statistical/systematic error on sin2b from will improve to somewhat beyond the 1% level. More than adequate • SUSY effects on sin2b in other modes can be quite large, tens of percent of the CKM value • With what precision must one measure sin2b in other, more difficult decay modes in order to establish an effect? • An example: • sin2b ( ) = 0.75(its current value), but the error is reduced to1%, s = 0.0075, • sin2b( ) = 0.60, i.e., the SUSY contribution to is 20% • For a 5 sigma effect: Dsin2b = 0.15/5 = 0.03, a 5% measurement • This requires a data sample of the size provided by a 1036 asymmetric B Factory D. Hitlin SLAC B-Day

  21. Extrapolated statistical errors on CP asymmetries BABAR measurement errors 10 to 50 ab-1 are required for a meaningful comparison Currentprecision D. Hitlin SLAC B-Day

  22. Probes of new physics - II • Measure branching ratios and kinematic distributions in rare decays that are sensitive to new physics, particularly those involving bs transitions Requires tens of ab-1 D. Hitlin SLAC B-Day

  23. Kinematic distributions and CP asymmetries in rare decays In SUGRA, sign of C7 determines sign of AFB • Bauer, Stech & Wirbel • Ball and Braun • Melihov, Nikitin and Simula • SM, ……> SUGRA with C7, MIA with suppressed Br,  MIA with enhanced Br Ali, et al. Standard Model predictions are robust D. Hitlin SLAC B-Day

  24. Probe of SUSY inand SUGRA SM Standard Model predictions are robust Ali and Safir D. Hitlin SLAC B-Day

  25. CPV in exclusive radiative decays Ali and Lunghi D. Hitlin SLAC B-Day

  26. MSSM:CPasymmetry inb  sg Bartl, Gajdosik, Lunghi, Masiero, Porod, Stremnitzer and Vives, hep:ph/0103324 • No EDM constraint • Obey EDM constraint D. Hitlin SLAC B-Day

  27. The effect of extra dimensions on UT parameters Buras, et al. D. Hitlin SLAC B-Day

  28. a g b Probes of new physics - III • Measure sides and angles of the Unitarity Triangle to best possible precision Improve measurements of |Vub| and |Vcb|essentially independent of new physicsSuper B Factory using the recoil technique Improve measurement of DmdSuper B Factory Measure DmsHadron machine Measure sin2aeffSuper B FactoryHadron machine Measure sin2aSuper B Factory using p0p0 Measure gSuper B FactoryHadron machine Measure sin2bSuper B FactoryHadron machine Improve calculations of |Vub|, |Vcb|, Lattice Test a + b +g =pto ~5-10% D. Hitlin SLAC B-Day

  29. TheB beam technique • Reconstruct a very large sample of of hadronic decays at the Y(4S) • In 10 ab-1, there are 4 x 107 fully reconstructed B’s in which thefour momentum of the recoil is known • Use this sample to study semileptonic decays and rare (inclusive) decays • The B beam technique, unique to e+e-, sacrifices statistics, but • Improves kinematics – reducing model dependence in|Vub| and |Vcb| studies • Reduces background for rare decays, especially those involving photons and neutrinos D. Hitlin SLAC B-Day

  30. f f’ Df (radians) measure f (f’)for B(B) from L = 2 ab-1 L = 10 ab-1 Df (radians) Df (radians) Luminosity (fb-1) Isolating the penguin contribution to sin2a using With 10 ab-1, the Gronau-Wyler construction can place a stringent limit on penguin amplitudes sin2aeff = 0.02±0.34±0.05 with 2aeff = 2a + 2d … but there is a 4-fold ambiguity!  s(Da)= 4 to 10 Cahn, Roodman D. Hitlin SLAC B-Day

  31. An independent estimate of the Gronau-Wyler construction Uses current central values D. Hitlin SLAC B-Day

  32. Measuring g with B DK • Gronau-Wyler, Atwood, Dunietz and Sonimethod: Comparison of BR’s for BDK modescan allow extraction of g • There is an 8-fold ambiguity • With sufficient luminosity, it is possible to resolve the ambiguity: with 10 ab-1, it appears that a precision of Dg1-2.5  can be achieved Study was done with 600 fb-1, scaled to 10 ab-1 Soffer Soffer D. Hitlin SLAC B-Day

  33. Snowmass 2001 scenario for improvement in the precision of CKM matrix elements Eigen, Kronfeld, Mackenzie D. Hitlin SLAC B-Day

  34. A projection to 2010 by the CKM Fitter group b b D. Hitlin SLAC B-Day

  35. Improvement of UT measurements can test the SM(Buras) • Optimal Unitarity Triangle Test • Improve measurements of |Vub| and |Vcb|, which are essentially independent of new physics contributions • This is best done at a 1036B Factory using the “B beam” technique • Measure Dms – domain of hadron machines • Improve theory estimates: |Vub|, |Vcb|, and • This yields a prediction forg,which is measurable both at aB Factory and in hadron experiments • Test of the mixing matrix element • With the above and with improved knowledge of eKand Dmd , we have the best possible prediction of the mixing matrix element and thus of mt, which can be compared with improved direct measurements D. Hitlin SLAC B-Day

  36. Simulations of more of these measurements are needed • Calculations needed at 10 and 50 ab-1 • How well can we measureVub with the recoil techniquefB with recoil techniqueagAFBin s+- or K(*)+- vs B(Brg) mixingB(tmg) PRAVDA Monte Carlo tool with a 1036-capable detector is nearly ready for these studies D. Hitlin SLAC B-Day

  37. Statistics and systematics • Nearly all important CPV measurements will remain statistics limited • Certain measurements, such as ACP in will be systematics limited at below the ~1% level • Other measurements, such as the extraction of sin2a or Vub will be limited by theory • Many of the most interesting measurements will be limited by statistics and backgrounds • This leads to the question of whether an upgraded detector can do better than a extrapolation would indicate • Does improved momentum resolution and improved particle ID lead to a better measurement of Spp by improving S/B ? • Does improved photon energy and angular resolution lead to a better measurement of tagged ? • Does longitudinal segmentation in the EMC lead to better p/e separation and thus better tagging? D. Hitlin SLAC B-Day

  38. Comparison of e+e-B Factories and hadronic experiments Wűrthwein D. Hitlin SLAC B-Day

  39. What is the future of experimental flavor physics? • Total BABAR, Belle data samples will amount to ~800-1000 fb-1 each • CDF (DØ), in areas which overlap e+e-, are being calibrated with TeV-II data Würthwien(SSI02): for untaggedBh+h-: 2 fb-1(CDF)  500 fb-1(BABAR, Belle)CDF/DØ can, of course, study Bs decay, but is unlikely, in general, to markedly improve on e+e- results in other areas • LHC experiments will bring statistics to the next level • In this context, is a new, very high luminosity e+e- effort warranted? D. Hitlin SLAC B-Day

  40. Sensitivity Relative to LHCb 1 year operation Atlas/CMS (1 year) BABAR 0.5ab-1 2002-2007 BTeV (1 year) LHCb (Value) s(Sin2b)Expt/s(Sin2b)LHCb 0.9/0.8 2.6 1.8 0.02 s(Sin2a)Expt/s(Sin2a)LHCb 1.8/3.0 3.2 0.4 ??? s(g)Expt/s(g)LHCb - - 1.0 10 s(-2dg+g) Expt /s(-2dg+g) LHCb - - 1.2 10 1.6/1.8 - 1.0 75 - 4.2 2.0 25K 1.2/1.6 - - 33 LHCb physics performance D. Hitlin SLAC B-Day

  41. At 1036,e+e- is fully competitive in rare decay studies * * Two arm BTeV SLAC-PUB-8970 D. Hitlin SLAC B-Day

  42. Comparison of 1 year yields – BTev and Super B Factory D. Hitlin SLAC B-Day

  43. a g A BTeV-generated comparison (updated from 1034) Number of flavor tagged B0p+ p -(B=0.45x10-5) Number of B-D0K-(Full product B=1.7x10-7) Bs, Bc and Lb studies are not done at U(4S) e+e- machines D. Hitlin SLAC B-Day

  44. Comparison of hadronic and 1036 reach • A comparison from the Snowmass E2 Group summary: D. Hitlin SLAC B-Day

  45. The 1036 environment 25MHz • Main concerns • Machine-related backgrounds • synchrotron radiation • particle backgrounds, due primarily to continuous injection • Radiation dose • Physics backgrounds – hadronic split-offs, ….. DIRC 100% Occupancy 7MRad/y EMC DCH SVT >10 hits/crystal/event D. Hitlin SLAC B-Day

  46. There is an upgrade path from BABAR to SuperBABAR • If it were feasible to modify the existing BABARdetector for use at a 1036 machine, there would be substantial savings in time, money and effort over a completely new detector • Upgrading the existing detector is beneficial in • Reducing costs by reuse of detector components and existing IR infrastructure • Use of existing software as a basis for new programs • Packaging an attractive proposal for funding agencies • An affordable, fast, radiation hard electromagnetic calorimeter is the key to the morphing of BABAR into SuperBABAR • An LXe EMC fits into the existing BABAR solenoid/flux return • There is a substantial cost saving over most crystals • Tracking with pixels/strips and a compact readout DIRC arecompatible with this design D. Hitlin SLAC B-Day

  47. An upgrade path from BABAR to SuperBABAR • IFR upgraded(ongoing) • Remove SVT,DCH, EMC,DIRC • New EMC –liquid Xe • New tracker –Two inner pixellayersSeven(?) thindouble-sidedSi-strip archlayers • New DIRC(s) with compact readout SuperBABAR BABAR D. Hitlin SLAC B-Day

  48. The MSSM (Minimal Symbolic Straw Man) Upgrade Detector • This BABARupgrade design has not been optimized • It is certainly possible to improve upon this design • This will be among the first orders of business when the physics foundation for 1036 has been solidified • We are currently implementing this design into a fast Monte Carlo called PRAVDA • Implementation includes the flexibility to • Vary parameters within a detector subsystem • Swap technologies for a given subsystem • TRACKERR package (complete error matrix) for vertex/tracking with an all silicon tracker has been implemented • Use parameterized descriptions for PID, EMC and IFR • A shower library is also under development for the EMC D. Hitlin SLAC B-Day

  49. Vertexing and Tracking • Pixel layers needed near beampipe • Double-sided strips for main tracking • Drift chamber is unlikely to survive 1036 • An all silicon tracker withtwo pixel layers + seven double-sided strip layersis a good candidate • Router = 60 cm • It is crucial to have a thin silicon chips and a light mounting structure to have adequately small multiple coulomb scattering D. Hitlin SLAC B-Day

  50. A silicon tracker with adequate momentum resolution is feasible Current DCH Double-sidedstrip @ 100mm A proposal to INFN to develop very thin double-sided detectors is in preparation Forti – TRACKERR/PRAVDA D. Hitlin SLAC B-Day

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