1 David Hitlin Snowmass July 17, e + e -  (4S) -  (5S) Collider Subgroup Report DRAFT

2 David Hitlin  Studies indicate that it may be possible to build an asymmetric collider at a luminosity of cm -2 s -1  This luminosity provides 10ab -1 (2 x B mesons) in a Snowmass year  Two approaches have been studied  9 on 3.1 GeV in the PEP-II tunnel U (4S), U (5S) with bg = 0.56  10.5 on 2.8 GeV in the SLC arcs U (5S) with bg = 0.88  Data samples are comparable to those obtainable at hadronic experiments  CP asymmetries and rare decays with B 0, B +  Rare decays with B s  e + e - and hadronic samples are often complementary  Physics goals are to search for physics beyond the Standard Model  Precision tests of consistency of Standard Model (Unitarity Triangle)  Patterns indicating new phases from SUSY or other SM extensions Doing physics at 10 36

3 David Hitlin Seeman’s Initial Parameters for in the PEP Tunnel HERLER Beam particle e + e - Beam energy (GeV) Circumference (m) 2200 Number of bunches 3492 Bunch length (mm) Beam lifetime (min) 5 3 Beam current (A) Beam-beam tune shifts 0.11 RF Frequency 476 MHz Luminosity (cm -2 s -1 )

4 David Hitlin Possible PEP-II/Super-B Data Sample Timeline

5 David Hitlin Physics motivation for  The unitarity triangle construction summarizes a set of overconstrained measurements of the quark sector of the Standard Model  What are the ultimate experimental and theoretical limits on the precision of such tests?  If new phenomena are found at LHC/NLC….. can precision heavy quark (or t ) physics help elucidate the situation? Buras

6 David Hitlin Physics Motivation  There are a variety of interesting topics  Improvement in CP asymmetry measurements 7 With 10 ab -1, : statistical uncertainty is comparable to that from LHCb, BTeV  sin2 b can be compared in many modes to interesting precision  sin2 a (A CP to be exact) and sin g ( U (4S) vs U (5S)) uncertainty comparable to that from LHCb, BTeV  Measurement of two and three body branching fractions (e.g. B 0  p 0 p 0 to a few percent) to the precision required for a clear estimation of penguin amplitudes  Measurement of f B, f D to useful precision to check lattice determinations  Interesting sensitivity to rare B, D and t decays, e.g. t  mg  New approaches to semileptonic or rare decay studies 7 Detailed distributions, not just branching fractions  Semileptonic decays with 1C fits  A CP for K * l + l -, etc  Many more

7 David Hitlin Expected errors in magnitudes of CKM matrix elements V ij Experimental Measurent  2001  2006  2011 Theoretical quantity  2001     V ub B (B  l ) B (b  ul ) V cb B (B  Dl ) B (b  cl ) V us B (K  l ) V cd B (D  l ) V cs B (D  l ) V td mdmd V ts msms Kronfeld/Hitlin

8 David Hitlin 30 fb -1 sin2  90 fb -1 sin2  sin2  180 fb -1 sin2  sin2  h r B A B AR Unitarity Triangle Sensitivity UPDATE for 10 ab -1

9 David Hitlin Triangle metrology at MeasurementMethodAsymmetry Error Angle error (degrees) sin2  time-dependent asymmetry, no penguins  isospin construction2-5 sin2  time-dependent asymmetry  3-5 sin(  ) 2

10 David Hitlin Models that may modify the Unitarity Triangle  Supersymmetry  43 phases, 80 constants  MSSM - with or without new flavor structure  Fourth quark generation  Flavor changing Z 0 couplings  Multi-Higgs doublet models  Left-right symmetric models  Extra d-type singlet quarks  Non-commutative geometry  Extra dimensions  There is a substantial literature on how these models could change the observed pattern of CP asymmetries, modify rare decay rates and angular distributions, etc.  It would be interesting to choose a few examples and explore accessible experimental measurements P2

11 David Hitlin Comparison of BTeV and Update of Stone/HEPAP table (10ab -1 ) ~1000 2x ~1000 2x10 7

12 David Hitlin Rare B decay sensitivity ~ Katayama (extrapolated) MeasurementTheory (SM)Sensitivity 1 ab -1 Sensitivity 10 ab -1 B (B  X s  ) (3.29 .21 .21)x x x10 -4 B (B  K*  ) 0.1 x x10 -5 A CP (B  X s  ) A CP (B  K*  ) B (B  X s ll) incl, exl 10%3% B (B  X s ) 20% B (B  ) 8x SES 3x10 -9 SES 3x B (B  ) (0.5-5)x x10 -7 B (B  s ) 10%3% A CP (B  s ) <0.1

13 David Hitlin Comparison of BTeV and SuperB A B Update of Stone/HEPAP table

14 David Hitlin Other hadron/e + e - comparison  Kim/Robertson

15 David Hitlin 10 ab -1 sensitivity to leptoquarks S. Yang

16 David Hitlin 10 ab -1 sensitivity to R-parity violating SUSY S. Yang

17 David Hitlin Estimate of ISR Signal Events for Super B-factory Decays Produced events (  10 6 ) in 10 ab -1 of data B.R.  Det. Eff. (%) Events reconstructed (  1000) Relative stat. error (%) D s branching fraction ~ D s leptonic decays ~ D + leptonic decay ~53 (1/3 of all D) ~53 (1/3 of all D)  c branching fraction ~ J/   (2S) leptonic width , Lou/Izen

18 David Hitlin Experimental situation  At a luminosity of :  50 kHz of Bhabhas  ~7 kHz other physics events  O (~10kHz) triggerable machine associated backgrounds in detector acceptance Robertson

19 David Hitlin CsI(Tl) Integration Time Robertson

20 David Hitlin Radiation Dose to EM Calorimeter Robertson

21 David Hitlin Detector design for  Two designs were considered to cope with increased backgrounds and radiation dose  Upgrade of B A B AR /BELLE 7 Retain solenoid/flux return 7 replace all detector systems  New compact high field design 7 Scale of this design is set by Molière radius of new rad hard, short scintillation decay time, crystals  To maintain  0 mass resolution (as precision of tagged B 0  0  0 branching ratio is a primary objective), calorimeter barrel radius is scaled by Molière radius

22 David Hitlin A compact, high field detector for SVT 2 Ly pixel 3 Ly Si strip 4 Ly Si strip tracker Compact DIRC LSO EMC 3T Coil IFR Fe + scint. fibers G. Eigen

23 David Hitlin

24 David Hitlin Detector systems for  Beam pipe  Want to increase  z vertex precision by ~ factor of 2 over B A B AR /BELLE 7 Improves CP measurement precision  Reduces light quark background for all b, c,  physics 7 Since it is difficult to reduce material in beam pipe, reduce lever arm with 1 cm radius beam pipe (vs current 2.5 cm)  Image charge heating in Au-plated Be beam pipe at 1 cm radius is about 10kW (Yamamoto) 7 This requires substantial engineering, but preliminary study indicates realizable mass flow rates for water cooling

25 David Hitlin Detector systems for  Vertex tracker 7 Two layers of pixel detectors at smallest possible radius 7 Three layers of arched double-sided Si strips  Must demonstrate efficient reconstruction in with high backgrounds  Radiation hardness should be adequate

26 David Hitlin Detector systems for  Main tracker  Drift chambers will not survive in environment 7 Use 4 layers of arched double-sided Si strips  With 3T solenoidal field and this configuration, charged particle momentum resolution is somewhat better than larger 40 layer drift chamber of B A B AR M. Sokoloff

27 David Hitlin Detector systems for  Particle Identification  DIRC provides excellent  /K/p separation to kinematic limit 7 Fused silica radiator bars are adequatley radiation hard 7 Background in standoff water tank is too high at Studies of quartz lens readout have begun  Resolution per track should be ~0.25 to 0.3 x B A B AR DIRC, providing >4   /K separation to 6 GeV/c 7 Design includes a forward DIRC to improve solid angle coverage B. Ratcliff/D. Leith

28 David Hitlin  EM Calorimetry  CsI(Tl) calorimeters of B A B AR /BELLE are likely to be too slow and not sufficiently rad hard for  There are other crystals, requiring some R&D that are more attractive  Liquid krypton is also a possiblility  New crystals have typically 2/3 the Molière radius of CsI  Radiation hardness is adequate Detector systems for 10 36

29 David Hitlin Scintillating Crystal Material Properties

30 David Hitlin I. Peruzzi, M. Piccolo Scintillating strip (MINOS) readout second coordinate by timing or relative pulse height Detector systems for 10 36

31 David Hitlin Trigger, Data Acquisition, Computing  It appears practical to retain the open trigger characteristic of e + e -, even at  Efficient for a wide variety of b, c,  decay modes  Redundant triggers to allow measurement of trigger efficiency  Design goals 7 Hardware-based tracking trigger 7 Per trigger deadtime <100ns 7 Overall dead time < 5% 7 Trigger rate upper bound 100 kTps  These requirements are less demanding than situation faced at LHC/BTeV  Moore’s Law scaling to ~2010 appears to be compatible with a CPU/disk installation of a size comparable to the current B A B AR computing installation Dubois-Felsmann/Young

32 David Hitlin Conclusions  A asymmetric B Factory presents an attractive physics program, with unique features and capabilities complementary to hadronic experiments  Precision tests of the Standard Model via the Unitarity Triangle construction  Searches for patterns in CP asymmetries that could indicate new physics  Sensitivities to rare decays that probe the TeV scale to an interesting level  Large samples of fully reconstructed pairs, making possible new studies of leptonic and semileptonic decays  It appears that an accelerator of this type can be built on an interesting time scale in existing tunnels  The experimental backgrounds and radiation dose are substantial, but appear to be tractable  A new detector, with upgraded tracking, particle id and calorimetric systems, will be required  Trigger, data acquisition and computing requirements are realizable