University of Southampton by alicejenny

VIEWS: 6 PAGES: 76

									                               Southampton
                               July 1999




Future of Heavy Flavour Physics:
    Experimental Perspective
           Sheldon Stone
         Syracuse University



                                             1
                Future Physics Goals:
                    Introduction
 Our goals are to make an exhaustive search for physics
  beyond the Standard Model and to precisely measure
  SM parameters.
 Here we ask what studies need to be done, not just
  what studies can be done.
 Measurements are necessary on CP violation in Bo and
  Bs mesons, Bs mixing, rare b decay rates, and mixing
  CP violation and rare decays in the charm sector.
 These quarks were present in the early Universe. There
  is a connection between our studies and Cosmology.
                                                           2
                       The CKM Matrix
We need to connect the weak eigenstates of
 quarks with the mass eigenstates




                                   
        weak eigenstates   VCKM    mass eigenstates

 If   n’s have mass there will be analogous matrix
                                                      3
             Proper Formulation of CKM
                       Matrix
              d                 s                    b
              1                                       1 2 
     u  1  l2                 l           Al  r  ih1  l   
                                               3
                                                               
              2                                       2 
                                                                 
V   c       l
                            1 2
                         1  l  ihA 2 l4
                            2
                                                   2
                                                    
                                               Al 1  ihl  2
                                                                 
        2                                                        
     t  Al 1  r  ih       Al2                    1          
                                                                 
                                                                 
 Good l3 in real part & l5 in imaginary part
 We know l=0.22, A~0.8; constraints on r & h
 Due unitarity there are 6 CKM triangles
                                                                      4
The 6 CKM triangles

              “ds” - indicates
               rows or
               columns used
              There are 4
               independent
               phases, which
               can be used to
               construct entire
               CKM matrix

                                  5
                    The 4 CKM Phases

         Vtb Vtd 
                *
                                  Vub Vud 
                                     *

         V V* 
   arg                 arg  *
                                  V V    
           cb cd                  cb cd 


         V Vcb 
               *
                                  V Vus 
                                        *
   arg 
         VV   
               cs
                           arg      
                                        ud
                *                 V V 
            tb 
                                        *
               ts                    cs 
                                        cd


 &  probably large,  small ~0.02,  smaller
                                                  6
                    Usual Triangle (for ref.)
 Real a,  &  must sum to 180o
 Therefore, any two will do IF we
  are really measuring the intrinsic
  angles
 New physics can hide, only
  these angle measurements not
  sufficient.
 Ex: Suppose there is new
  physics in Bo-Bo mixing (q) &
                                       Two   sides |Vub/Vcb| &
  we measure CP in yKs and pp,
                                        |Vtd/Vts| important.
  then 22q, 2a2aq, &
                                        BTeV can measure the
  22a22a, new physics
                                        latter from Bs mixing
  but a 180o                                               7
                         Ambiguities

Suppose we measure
 sin(2) using yKs,
 what does that tell us
 about ?
Ans: 4 fold ambiguity-
 , p/2, p, 3p/2
 Only reason h>0, is Bk>0
  from theory, and related
  theoretical interpretation
  of e                                8
             Problems with measuring a
                   using Bopp
 Using Bopp would be nice, but
  large Penguin term, CLEO:
  B(Bo p+p-) < 0.84 x 10-5, while
  B(Bo K+p-) =(1.4±0.3±0.2)x10-5
 The effect of the Penguin must be
  measured in order to determine a.
  Can be done using Isopsin, but      for s get K-

  requires a rate measurements of
  ppo and popo (Gronau & London).
  However, this is daunting.
                                                     9
                   Measuring a using
                   Borp  pppo
A Dalitz Plot analysis
 gives both sin(2a) and
 cos(2a) ( Snyder & Quinn)
CLEO has measured
 the branching ratios
 B(Brop =
 (1.5±0.5±0.2)x10-5
B (Borp + rp          Snyder & Quinn showed that 1000-
                             2000 tagged events are sufficient
   = (3.5±1.0±0.5)x10-5                                          10
               Comparison of rp modes

Final State: rp rp rpo rop         r op o
CLEO(10-5):    3.5±1.2 <7.7 1.5±0.5±0.2 <1.8
Ciuchini et al.: 1.0-7.5 0.2-1.9 0.3-2.6 0.5-1.1   0.00-0.02
Ali et al.:   2.1-3.4 0.6-0.9 1.1-1.6 0.1-0.7      0.00-0.02
B(B+  roK+) = < 2.2x10-5 @ 90% c.l. (CLEO)
{To measure the three neutral rp modes, requires
  triggering on hadronic decays with high efficiency,
  RICH particle ID and high quality photon
  detection}                                        11
                         More on a

Using rp Dalitz Plot analysis, sin(2a) and
 cos(2a) are measured, only one ambiguity
 remains a & pa
To remove this use Bopp.This works because
 of large Penguin rate (Grossman & Quinn)
a(pp)-a(rp)=-2(AP/AT)cos(dP-dT)[cos(2a)sin(a)]
   Usefactorization to get sign of AP/AT (-)
   Theory says cos(dP-dT) is small


                                                  12
                   Ways of measuring 

 May be easier to measure than a
 There are 4 ways of determining 
    Time dependent flavor tagged analysis of BsDsK
    Measure rate difference between B-DoK- and B+DoK+
    Rate measurements in Kop and Kp (Fleisher-Mannel) or rates
     in Kop & asymmetry in Kpo (Neubert-Rosner) . Has theoretical
     uncertainties but can be useful.
    Use U spin symmetry ds: measure time dependent
     asymmetries in both Bopp& BsKK (Fleischer).
    Ambiguities here as well but they are different in each
     method, and using several methods can resolve them.
                                                                      13
            BsDsK Decay processes
                     ±




Diagrams for the two decay modes, B ~ 10-4 for each




                                                      14
B-[K+p-]K- Decay processes




                      B ~ 10-6




                      B ~ 2x10-7

                                 15
              What do we need to measure
                     involving ?
 Phase of Bo-Bo mixing,  using yKs          (done soon? precision?)

 Measure  using other modes: fKs,hKs, ypo
 Remove ambiguities if possible
   Measure interference in yK*. However, either must make
    theoretical assumption (factorization) to guarantee that fsi don’t
    change sign of strong phase-shift or measure Bs yf & use
    SU(3)
   Kayser: Measure time dependence using yKs,

     Kspln, has a cos(2) term (loss of rate)

                                                                         16
                                    Decay Widths for Bo  yKs,
                                                           Kspln
 t B , t K  
e B t B {e   s t K [1  sin(2) sin(m B t B )]                              cos(2)>0
 e   s t K [1  sin(2) sin(m B t B )]                                       cos(2)<0
           
               1
                   s   L t K
 ( )2e       2
                                    [cos(m B t B ) cos(m K t K )
        cos(2) sin(m B t B ) sin(m K t K )]}


 top sign for Bo, bottom for Bo
 3rd line 1st pair for p-l+n (K),
     2nd pair for p+l-n (K)
                                                                     t K integrated over t B
 CPT tests?
                                                                                               17
                A Critical Check using 

 Silva & Wolfenstein, (Aleksan, Kayser & London), propose a
  test of the SM, that can reveal new physics; it relies on
  measuring the angle . (This is the sine qua non Unitarity check)
    BTeV can use CP eigenstates to measure , for example
      Bsyh, hr
    Can also use yf, but need complicated angular analysis
    The critical check is
                                      sin  sin 
                            sin   l 2

                                      sin(   )
    Very sensitive since l 0.2205±0.0018
    Since  ~ 0.02, need lots of data
                                                                      18
                    More checks using 

 Other   checks using |Vtd/Vts|, |Vub/Vcb| possible

                2
         Vub sin  sin(   )
 sin  
         Vcb      sin()
                2
         Vtd sin  sin(   )
 sin  
         Vts      sin( )
           might provide best measurements of
 Ultimately,
 these CKM ratios!
                                                       19
                 Other critical CKM
                   measurements
Bs mixing
    Use Bs Ds p to determine xs
   Find  by comparing lifetime for yh or K+K-
    with Ds p
   If  is large enough ~10%, then other interesting
    measurements are possible
|Vub|, how do we do this with minimal
 theoretical error?

                                                         20
                         Rare b Decays

                                   Exclusive Rare Decays
                                    such as Br,
                                    BK*l+l
                                   Inclusive Rare Decays
 Possibilities for New Physics     such as inclusive bs,
    W- in loop is replaced by      bd, bsl+l. Can
    other charged object such
                                    hadron machines do
    as H-, X -
                                    this? Probably using
    new fermion like objects
    replace t
                                    same technique as
                                    CLEO.
                                                              21
                     Charm decays

Predictions of the Standard Model contribution
  to mixing and CP violation in charm decay are
  small. Thus, this provides a good place to
  search for New Physics.
   Currentexperimental limit on mixing, rD<5x10-3,
    SM expection rD~10-8
   CP current limit is ~10%, SM expectation is 10-3




                                                       22
                    Summary of required
                    measurements for b’s
Physics             Decay Mode         Vertex    K/p    det Decay
Quantity                               Trigger   sep         time 
sin(2a)         Borppppo                           
sin(2a)         Bopp & BsKK                            
cos(2a)         Borppppo                           
sign(sin(2a))   Borp & Bopp                        
sin()          BsDs K                                     
sin()          BoDo K                         
sin()          BK p                                 
sin(2)         BsJ/yh, J/yh                             
sin(2)         BoJ/yKs
cos(2)         BoJ/yK* & BsJ/yf
xs              BsDsp                                     
 for Bs       BsJ/yh, KK, Dsp                              23
           Summary of Standard Model
                    Tests
 Check that a     = 180o, after removal of
  ambiguities; necessary if we have properly measured
  these quantities
 Check that the Silva-Wolfenstein test has been met:
                         2 sin  sin 
                sin   l
                           sin(   )
 Check that magnitude ratios |Vtd|/|Vts| and |Vub| / |Vcb|
  are consistent with determined a, , , 
 Search rare decays for anomalous rates, or dilepton
  polarizations
                                                              24
          Current Status: Brief Summary

We know xd and have limit on xs
We know |Vcb| & |Vub|, but how accurately?
    What   is the meaning of a theoretical error?
       Is it Gaussian distributed?
       Does statistics work in combining undefined errors?

    Whatis the error on Vcb?
   What is the error on Vub?
 We know lifetimes


                                                              25
                               We know lifetimes
                              (still some mysteries)
total = 1/t
                    2

                   1.9
                   1.8

                   1.7
B lifetimes (ps)




                   1.6

                   1.5   B+
                                 Bo
                   1.4
                                       Bs              “Low”
                   1.3

                   1.2
                   1.1
                                             Lb
                    1

                                                               26
         Heavy Quark Effective Theory

HQET tells us that in first order when a b quark
 transforms to a c quark with the c going at the
 same velocity as the b, the form factor is 1 in
 first order AND the corrections to 1 can be
 calculated
The form-factor therefore known to be 1-
 correction, at maximum q2, called w=1, where
          M2  M2 *  q 2
     w B        D
            2M BM D*
                                                    27
                             |Vcb| from BD*l n

Use BD*l n because the decay rate is largest
 for and the corrections are better determined.
In HQET there is one “universal” form-factor
 function, so we don’t have to deal with 3 form-
 factors
To find Vcb measure value at w=1, here D* is at
 rest in B rest frame                        m  m                                    2  
                                                                        1  2wD*
                                                                                     D* 
d(B  D*ln)   G2                                                               mB m 2
              F 3 Vcb F2 (w)(m B  m D* ) 2 m 3 *   w2  1  4w(w  1)
                      2                                                                B
     dw       48p
                                               D                                       2 
                                                                             m D*     
                                                                             1     
                                                             
                                                              
                                                                             
                                                                             
                                                                                     
                                                                                  mB    
                                                                                         
                                                                                         28
                CLEO Measurement



   background




background




                                   29
               Vcb results, an example

 To get results fit using shape proposed by Caprini et
  al, or Boyd & Grinstein, or in CLEO case by Stone
 Use F(1)=0.91±0.03, from Caprini, Uraltsev…..
 Results
    DELPHI: (41.2±1.5±1.8±1.4)x10-3
    ALEPH: (34.4±1.6±2.3±1.4)x10-3
    OPAL: (36.0±2.1±2.1±1.2)x10-3
    CLEO: (39.4±2.1±2.2±1.3)x10-3
    World Average 0.0381±0.0021 by adding
      theoretical error in quadrature with exp error.     30
                   Theoretical Value of F(1)
 Lim F(1) = 1 as mb  ,
 F(1)=1+O(as/p)+d1/m2+d1/m3 (no d1/m , Lukes thrm)
    F(1)=0.91±0.03,    from Caprini, Uraltsev…..
    F(1)=0.89±0.06, from Bigi
    Can we get an accurate non-quenched value from the Lattice?
    The errors are not consistent. What do the errors mean?
 Bigi: “In stating a theoretical error, I mean that the real value can
  lie almost anywhere in this range with basically equal probabilty
  rather than follow a Gaussian distribution. Furthermore, my
  message is that I would be quite surprised if the real value would
  fall outside this range. Maybe one could call that a 90% confidence
  level, but I do not see any way to be more quantitative.”
                                                                          31
                  QCD Sum Rules for |Vcb|

 Using Operator Product Expansion & Heavy Quark
  Expansion, in terms of as(mb), L, and the matrix
  elements l1 and l2, we can accurately determine Vcb.
 These quantities arises from the differences
                    l1  3l 2                       l  l2
    mB  mb  L                , m B*  m b  L  1      ,
                      2m b                           2m b
 From B*-B mass difference, l2 = 0.12 GeV2

                                   a         L          a 
                           1  1.54 s  1.65    1  0.87 s 
                                     p                     p 
                 2
            2       5
          G F Vcb m B                         mB 
   sl              0.369
             192p 3
                                   L2        l1         l2 
                            0.95 2  3.18 2  0.02 2 
                                   mB        mB         mB 
                                                                  32
            Measurement of sl & moment
                     analysis
Use total Branching
 Ratio Measurement
   CLEO   using lepton tags
    (10.490.170.43)%
   Lifetime 1.6130.020ps
    sl= 65.03.0 ns-1
   (note   LEP 68.61.6 ns-1 )
“Moment Analysis” of
 BXln, Mx and El
                                      33
             Result for |Vcb| Using Moment
                         Analysis
 Discrepancy between
  hadronic mass moments and
  El moments
 Theoretical estimates favor
  Mx moments
 Taking Mx estimates only:
   L    = 0.330.020.08 GeV
    l1=-0.130.010.06 GeV2
 Ligeti claims:
  |Vcb| = 0.04150.0012, but      Is this an experimental problem
                                  or an inherent problem in OPE?
  it would be foolish to use it                                 34
             Vub from lepton endpoint

B & value of
 Vub depends
 on model,                   Y(4S) data
                             bcln 
 since fraction               continuum
 of leptons in
 signal region
 depends on
 model!

                                           35
               Vub from pln and rln

pln  p0ln


                               bu backrounds
                               & cross-feeds

rln  r0ln                   bc backrounds
      woln
                               bu backrounds
                               & cross-feeds

                                            36
                       New CLEO form-factor
                            Analysis
Find rln  r0ln woln as function of El using
likelihood method to fit M(pp) & E distributions,
where E = Er+El+|pmiss|-Ebeam
                       El >2.3 GeV/c
 r modes with E cut        r modes with M(pp cut   r modes with both cuts



            buln
            bkgrd
               bcln



      M(pp)                            E                     El              37
                    Form-factor Results

 In general 3 form-factors for
  0-  1- transitions, but we do
  not have enough precision to
  disentangle them
 Data shows the need for more
  data
 Combining with older result:


|Vub|=(3.250.14 0.29 0.55)x10-3
                 +0.21



                                          38
                     Summary of |Vub| Results
 LEP measurements use 8% theoretical
  error as given by Uraltsev. However
  Jin’s similar calculation claims a 10%
  error but differs by 14%. I use a 14%
  theory error here
 Since the LEP Monte-Carlo
  calculations are highly correlated, I
  take a common 14% systematic
  uncertainty
 The exclusive channels rule out the
  Korner & Schuler (KS) model (gets
  the wrong V/P ratio), but have large
  errors
 The CLEO endpoint results have the
  best statistical error. Hard to estimate
  the theoretical error. I take 14%.
                                                39
                                CKM Plot


                                                                 68% c.l.

                                                                 95% c.l.




                                         From Parodi, Roudeau & Stocchi


                                    Several authors have done these
 Dominant error in e band is
  Vcb                              fits: Mele, (long ago Rosner).
                                   Question: If we find a region well
 1 errors, not to be believed
                                   outside of contour after measuring
 good art?                        angles is SM ruled out?            40
             Short Term Perspective

e+e- B factories at Y(4S) will turn on: CLEO III,
 BaBar, Belle
Since CLEO III didn’t have an upgrade talk, I
 will show you some pictures. Detector
 installation is occurring now.




                                                     41
            CLEO III (not yet shown here)

 Yes Virginia CLEO will continue with symmetric
  beams and higher L
 Illustrative lesson: Best CESR Performance
 “These are the highest values measured during normal
 High Energy Physics running with a beam energy of
 5.3 GeV. They did not necessarily occur
 simultaneously:
    Peak  luminosity 8.0 x 1032 cm-2/sec
    Best integrated luminosity 40 pb-1 per day, 750 pb-1 per
     month, 4.4 fb-1 per year”
                                                                42
                   CLEO II  CLEO III
 Replace everything inside the magnet coil to allow for interaction
  region quads to move closer (higher L) and allow for new
  particle identification system (RICH)




                                                                   43
          Some CLEO Pictures
A Silicon Ladder




The RICH Radiator




                               44
      More CLEO III RICH photos


The Photon Detectors   Mating the Two Cylinders




                                                  45
           Expected Results from e+e- B
                    factories
Babar & Belle can & should measure sin(2)
For everything other than CP violation via
  mixing CLEO III will be directly competitive
   Rare  decays
   CP violation in rare decays
   Better understanding of Vcb, especially using D*oln
    at maximum q2
   Better understanding of Vub using moments and
    higher statistics data on exclusive decays
   Lattice calculations may help
                                                          46
             Short Term Competition

Hadron colliders
   HERA-b  has the potential to also measure sin(2)
   CDF already has already taken the first steps toward
    measuring sin(2). Next run will start ~Aug. 2000.
   CDF could also measure xs.




                                                           47
          Why do b & c decay physics at
               hadron colliders?
 Large  samples of b quarks are available, with the
  Fermilab Main Injector, the collider will produce
  ~4x1011 b hadrons per 107 sec at L = 2x1032 cm-2s-1.
  Rates are potentially 5 x larger at LHC.
 e+e- machines operating at the Y(4S) at L of 3x1033
  produce 6x107 B’s per 107 s.
 Bs & Lb and other b-flavored hadrons are accessible
  for study.
 Charm rates are ~10x larger than the b rate


                                                         48
               Main detector challenges
 Problems:
   b/tot~ 1/500 at Fermilab, 1/100 at LHC
   Background from b’s can overwhelm “rare” processes
   Large data rate just from b’s - 1 kHz into detector
   Large rates cause Radiation damage to EM calorimeter; photon
    multiplicities may obscure signals
 Solutions   for BTeV:
   Use  detached vertices for trigger and background rejection
   Have excellent charged particle identification & lepton id
   Dead-timeless trigger and DAQ system capable of writing kHz
    of events to tape
   Use PbWO4 crystal calorimeter                                  49
              Fundamental Detector
                   Principles
Necessary to trigger efficiently on purely
 hadronic final states - detached vertex trigger
Necessary to reconstruct final states with
 excellent decay time resolution, good efficiency
 and mass resolution
Necessary to detect final states with  or po
 efficiently with good energy resolution
Necessary to able to identify p/K/p

                                                    50
         Characteristics of hadronic b
                 production
 The higher momentum     b production peaks at large
 b’s are at larger h’s   angles with large bb correlation









              h                                        51
                     Long Term View

 All measurements I have discussed, must be done
 Hadron machines produce enough b’s, & Bs
 We will have LHCb, Atlas, CMS & possibly BTeV
 Atlas & CMS work in central region, they lack the
  ability to trigger on purely hadronic final states and the
  lack particle id. Atlas also lacks an excellent EM cal
 Although LHCb & BTeV can do all the measurements
  that Atlas & CMS can do, there is a class of
  measurements involving J/y decays, for which they
  can compete
                                                               52
            The BTeV Detector

Inside the beam pipe


                        -PbWO4 crystals




                                          53
            The C0 Interaction Region

 Construction finished    BTeV is designed to be
                            compatible




                                                     54
The LHCb Detector




                    55
                The BTeV Pixel Detector

 Pixels necessary to
  eliminate ambiguity
  problems with high track
  density; Essential to our
  detached vertex trigger
 Crucial for accurate decay
  length measurement
 Radiation hard
 Low noise

                                          56
                  Pixel Trigger Description

   Triplets used to get space point & mini-vector, called a ‘station hit’
   Station hits are organized
      into f-slices
   Tracks are found in
    these f-slices
      full pattern
       recognition
        is performed
      Minimum track p cuts are applied
   Event level processors then find primary vertices & detached tracks
                                                                         57
              Detached Vertex Trigger

 Level I Trigger uses information from the Pixel
  Detector to find the primary vertex and then look for
  tracks that are detached from it
 The simulation does the pattern recognition. It uses
  hits from MCFast including multiple scattering,
  bremsstrahlung, pair conversions, hadronic
  interactions and decays in flight
 Detailed studies of efficiency and rejection for up to an
  average of three interactions/crossing

                                                              58
            BTeV Trigger Performance

 For a requirement of at least 2 tracks detached by more
  than 4, BTeV triggers on only 1% of the beam
  crossings and achieve the following efficiencies for
  these states:

       State     efficiency(%)   State    efficiency(%)
       B  p+p-        55        Bo  K+p-       54
       Bs  DsK        70        Bo  J/y Ks     50
       B-  DoK-       60        Bs  J/yK*      69
       B-  Ksp-       40        Bo  K*        40


                                                            59
           Ring Imaging Cherenkov’s

 Both LHCb & BTeV have excellent p/K/p using gas
  (C4F10) & possibly also aerogel radiators
 Visible photons detected use phototubes or HPD’s




                                                     60
                     EM calorimeters

 BTeV uses 22 cm long         LHC-b uses a Shaslik
  PbWO4 crystals developed      EM cal with scintillating
  by CMS                        fibers and lead
 20k-40k crystals             There is also a
 Crystals are radiation hard   preshower detector
 Scintillation is fast, 99%   This is very radiation
  of light emitted < 100 ns     hard
 BTeV will use phototube
  readout since calorimeter
  is not in a magnetic field
                                                            61
                 Expected EM Calorimeter
                       Performance
         BTeV                             LHCb
  Energy resolution:

 E 
        1.6%   2
                      0.55%
                                          10%  1.5%2
                                                2
                                   E 
                              2

             E                              E
                      E in (GeV)
  Position resolution:

 x (m) 
             35002  2202
                 E
                                                            62
           Physics Simulations: Some
                    Lessions
BTeV simulations do have pattern recognition
 (except for trigger); smears hits and refits the
 tracks using “Kalman Filter,” has multiple
 scattering, bremsstrahlung, pair conversions,
 hadronic interactions and decays in flight
 included
Parameterized shower energy deposits
Next, follow examples

                                                    63
                The CP asymmetry in Bop+ p-

   The average decay
    distance and the             B momentum
    uncertainty in the average
    decay distance are
    functions of B
    momentum:
    <L> = 480 m x pB/mB
                                       Decay distance error




                                                              64
             Bop+ p-: L/ distribution

 L/ = Decay length/error
  is very important in
  rejecting background
  both at trigger level and
  in analysis
 Much better in Forward
  (BTeV) geometry than
  Central geometry
  because b’s are moving
  faster                        L/
                                          65
           Bop+ p- analysis: the importance
              of particle identification
   Require that each p be properly identified in the RICH.
    Otherwise the measurement is probably impossible.




                                                              66
              A sample calculation: Bop+p -
                                                              BTeV        LHCb
Cross-section                                                  100 µb      500 µb
Luminosity                                                     2x1032      2x1032
# of Bo/Year (107 s)                                          1.4x1011     7x1011
B(Bo p+p-)                                                   0.75x10-5   0.75x10-5
Reconstruction efficiency                                        0.06       0.032
Triggering efficiency (after all other cuts)                     0.50        0.17
# (p+p-)                                                       34,000      28,560
eD2 for flavor tags (K±, l±, same + opposite side jet tags)      0.1          0.1
# of tagged p+p-                                                3,400       2,900
Signal/Background                                                0.6           1
Error in p+p- asymmetry (including bkgrd)                      ±0.023      ±0.019
                                                                                      67
                      Measuring a Using
                      Bo r p p+p-po
            BTeV        LHCb
B (x10-5)    4           4
efficiency 1.0x10-2     1.7x10-4      BTeV
# found     28,000       2,400
# tagged     2,800         240

 Backgrounds not yet
  determined
 BTeV has more than enough
  for Dalitz plot analysis

                                             68
                       xs Reach

Both LHCb & BTeV
 have excellent xs
 reach using BsDsp-
LHCb gets a 5
 signal for ms < 48
 ps-1 (xs < 68)



                                  69
                       Comparisons

Here I compare BTeV with LHCb and with
  other experiments that posses the all the
  necessary elements for a state of the art heavy
  quark experiment:
   Ability  to trigger efficiently on purely hadronic
    final states
   Ability to detect final states with  or po efficiently
    with good energy resolution
   Ability to identify p/K/p

We are left with e+e- B factories                            70
                Comparisons of BTeV
                 With e+e- B factories
 Number of flavor tagged Bop+ p - (B=0.75x10-5)
           L (cm-2s-1)    #Bo/107s e eD2 #tagged
e+e-       3x1033      1nb 3.0x107 0.4 0.4     46
BTeV       2x1032 100b 1.4x1011 0.03 0.1    3400
 Number of B-Do K -
            L(cm-2s-1)    #Bo/107s e      #
e+e-        3x1033     1nb 3.0x107 0.5       2
BTeV        2x1032 100b 1.4x1011 0.015    320
Bs , Bc and Lb not done at Y(4S) e+e- machines
 Number of tagged, reconstructed Bo decays to rp is a
  factor of at least 10 higher for BTeV.                 71
                      Comparisons of BTeV
                          with LHCb
   Advantages of LHCb
      b 5x larger at LHC, while t is only 1.6x larger
      The mean number of interactions per beam crossing is 3x lower at LHC,
       when the FNAL bunch spacing is 132 ns
      LHCb HAS BEEN APPROVED!
   Advantages of BTeV (machine specific)
      The 25 ns bunch spacing at LHC makes 1st level detached vertex
       triggering more difficult.
      The 7x larger LHC beam energy causes problems: much larger range of
       track momenta that need to be analyzed and large increase in track
       multiplicity, which causes triggering and tracking problems
      The long interaction region at FNAL, =30 cm compared with 5 cm at
       LHC, somewhat compensates for the larger number of interactions per
       crossing, since the interactions are well separated
                                                                               72
                Comparisons with LHCb II

 Advantages    of BTeV (detector specific)
   BTeV   is a two-arm spectrometer (gives 2x advantage)
   BTeV has vertex detector in magnetic field which allows rejection
    of high multiple scattering (low p) tracks in the trigger
   BTeV is designed around a pixel vertex detector which has much
    less occupancy, and allows for a detached vertex trigger in the first
    trigger level.
               for accumulation of large samples of rare hadronic decays and
      Important
      charm physics.
      Allows BTeV to run with multiple interactions per crossing, L in excess of
      2x1032 cm-2 s-1
   BTeV    will have a much better EM calorimeter
                                                                                73
                 The Status of BTeV

 BTeV is an approved R&D project at Fermilab, E897,
  whose purpose to generate a full proposal for a heavy
  quark decay experiment at the Tevatron collider by
  May 2000.
 BTeV has submitted a preliminary
  technical design report in May of 1999.
 BTeV has been asked to submit a full
  proposal in May of 2000.


                                                          74
                            Conclusions

 A complete program to test the Standard Model and
  see beyond it requires the measurement of CP
  violation and rare decays in the b & c sectors.
 A complete experiment requires:
    large   b rates to measure small B’s & asymmetries in B & Bs
    ability to trigger on purely hadronic final states
    excellent mass & decay time resolution
    ability to identify leptons p/K/p
    ability to use final states with  and po



                                                                    75
                                  Conclusions II
 Short term
    We will see a statistically significant measurement of sin(2) from e+e- B
     factories and CDF, HERA-b
    Perhaps a measurement of xs from CDF
    Beware of fit confidence levels where theoretical errors dominate

 Long term precision measurements of a, , ,  & ambiguity
  removals from BTeV & LHC-b with some important contributions
  from Atlas & CMS
 Ultimate tests will couple magnitudes l, |Vub/Vcb|, |Vtd/Vts| with the
  phase measurements where  is essential
 Moreover, BTeV & LHCb are powerful enough experiments to do
  physics beyond that mentioned here which may become much more
  interesting in the future, ex: CPT tests                               76

								
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