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Physics Requirements. for a. Super Factory Trigger. B. David Hitlin Caltech December 3, 2004. Physics objectives of a Super B Factory.

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Physics Requirements

for a

Super Factory Trigger

B

David Hitlin

Caltech

December 3, 2004

D. Hitlin Super B Factory Trigger Workshop


Physics objectives of a super b factory
Physics objectives of a Super B Factory

  • The physics objectives of an experiment at a Super B Factoryrevolve around the search for New Physics. The specific approaches fall into several distinct categories

    • Improvements in the classic unitarity triangle-related measurementsto the “ultimate” precision [a balance of theoretical, statistical and systematic uncertainties]

      • UT angles

        • measure asymmetries with minimum systematic error

          • lepton tag has smallest systematics

        • Measure branching ratios of rare modes for g

      • UT sides

        • use the recoil method to reduce backgrounds and theoretical uncertainties

    • Maximum sensitivity for very rare decays – B, D, t

      • Branching fractions

      • ACP, AFB

      • Kinematic distributions

D. Hitlin Super B Factory Trigger Workshop


The recoil physics method at the 4 s

p

Brecoil

e-

D*

n

Breco

e+

Xu

The recoil physics method at the¡(4S)

  • Fully reconstruct one of the two

  • B’s in hadronic modes (for some

  • topics, in semileptonic modes as well)

  • …and do it with “high” efficiency

  • Semileptonic decays

    • B D(*)n, B (p,r)n, BXc,un …… ()

    • B D(*)tn (sensitive to New Physics)

    • B D(*)tn

  • Purely leptonic decays Btn, ….

  • B Knn

  • Binvisible

  • B Xsg

  • The rest of the event is the otherB, whose four-momentum is known

You have a single Bbeam, withreduced systematics inVcb, Vubstudies, and

reduced backgrounds for rare decays, especially those involving neutrinos or photons

D. Hitlin Super B Factory Trigger Workshop


Measurement precision angles of the unitarity triangle
Measurement precision – angles of the Unitarity Triangle

Theory: a ~5%, b ~ 1%, g ~0.1%

D. Hitlin Super B Factory Trigger Workshop


Probes of new physics i
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 Super B Factory Trigger Workshop


Extrapolated statistical errors on cp asymmetries
Extrapolated statistical errors on CP asymmetries

BABAR measurement errors

10 to 50 ab-1 are required for a meaningful comparison

Currentprecision

D. Hitlin Super B Factory Trigger Workshop


Measurement precision rare decays
Measurement precision – rare decays

D. Hitlin Super B Factory Trigger Workshop


Measurement precision rare b decays
Measurement precision - rare B decays

D. Hitlin Super B Factory Trigger Workshop


Measurement precision rare decays1
Measurement precision – rare decays

Masiero, Vempati, Vives

tmg is sensitive to 23 generation mass insertions,(analogous to b sss) but in the lepton sector

D. Hitlin Super B Factory Trigger Workshop


fKS BABAR(now)

fKS 30 ab-1

The scale of New Physics

  • Mass insertion approximation: model-independent

f23 mass insertion

f13 mass insertion

DACP (J/ KS-fKS)

DACP (J/ KS-p0KS)

Ciuchini, Franco, Martinelli, Masiero, & Silvestrini

D. Hitlin Super B Factory Trigger Workshop


Physics demands an open trigger
Physics demands an open trigger

  • In the face of the impressive rates and amounts of data that will be encountered at a Super B Factory, the first reaction is usually to think about a restrictive trigger

  • This is unlikely to work, since the physics requires

    • A large, unbiased sample of fully reconstructed B decays

      • Recoil studies, ACP, B to invisible, etc.

      • Sensitivity to rare t decays

  • A trigger that can do this will manifestly provide a large sampleof D decays as well

D. Hitlin Super B Factory Trigger Workshop


The new snowmass year
The New Snowmass Year

  • The “Snowmass Year” was defined in 1988, based on data from CESR/CLEO:

    1 Snowmass Year = 107 s

  • The Snowmass Year factor is meant to account for

    • The difference between peak and average luminosity

    • Accelerator and detector uptime

    • Deadtime

    • ………………………..

  • PEP-II performance April 2003-April 2004 (Dec 03 Trickle LER, Feb 04 Trickle HER)

  • Given the excellent performance of PEP-II/BABAR and KEK-B/Belle, and the advent of trickle injection, the modern B factory Snowmass Year constant is 1.4 x 107

  • Thus we can integrate 10 ab-1/year with 7 x 1035cm-2s-1, instead of with 1036cm-2s-1

  • D. Hitlin Super B Factory Trigger Workshop


    Occupancy extrapolations are uncertain but sobering

    1036

    7x1035

    2x1035

    20%

    1036

    7x1035

    2x1035

    Now: 8 physics clusters

    Occupancy extrapolations are uncertain, but sobering

    D. Hitlin Super B Factory Trigger Workshop


    Tracking will have to be done with silicon not gas
    Tracking will have to be done with silicon, not gas

    • We will have to develop a silicon tracking trigger

    D. Hitlin Super B Factory Trigger Workshop


    Top module
    Top module

    D. Hitlin Super B Factory Trigger Workshop


    Bottom module
    Bottom module

    D. Hitlin Super B Factory Trigger Workshop


    Midplane module
    Midplane module

    574%

    D. Hitlin Super B Factory Trigger Workshop


    There will be pixels striplets and dssd layers
    There will be pixels, (striplets) and DSSD layers

    Pixel or striplets (2 layers)

    Intermediate DSSD(3 layers)

    Central Silicon Tracker(4 layers)

    R(outer) = 60 cm

    D. Hitlin Super B Factory Trigger Workshop


    There is a fast rad hard replacement crystal for csi tl
    There is a fast, rad hard replacement crystal for CsI(Tl)

    D. Hitlin Super B Factory Trigger Workshop


    Comparison of csi tl lso liquid xe
    Comparison of CsI(Tl), LSO, Liquid Xe

    D. Hitlin Super B Factory Trigger Workshop



    An upgrade path from b a b ar to super b a b ar
    An upgrade path from BABAR to SuperBABAR

    EMC  Liquid Xe scintillation or fast, rad-hard crystals (LYSO)

    DIRC  Faster, pixelated readout

    SuperBABAR

    SVT 5 layers of double-sided striplets 2 layers of thin pixels + 3 layers of thin pixels

    Tracker  4 layers of thin double-sided Si

    + New trigger and DAQ system

    BABAR

    D. Hitlin Super B Factory Trigger Workshop


    Projections depend heavily on the luminosity term
    Projections depend heavily on the luminosity term

    Cross sections:

    • BB: 1 nb 1010BBpairs/year

    • uds: 1.6 nb, c: 1 nb

    • leptons (m, t): 0.78 each

    • recognizable Bhabhas: ~50nb

  • The Level 1 trigger rate:

    • BABAR/PEP-II projections show that the hardware trigger rate will be dominated by luminosity-related interactions at luminosities above 1034 .

    • At 7x1035, this gives a rate for a BABAR-like hardware trigger of about 50K events per second. Half of these are scaled Bhabhas. There are ~ 6K beam background-like events per second.

    • Unless we are clever we might have to cope with a ~100K/second L1 rate !

    • Event size ~50K (~2X BABAR)

  • How well must we know the efficiency of each trigger line?

    • Precise absolute branching ratios may not be of extreme importance

  • Scaled from GPDF in Hawaii

    D. Hitlin Super B Factory Trigger Workshop


    The challenge
    The challenge

    • Design a trigger D/A system with a silicon tracking plus fast calorimeter trigger which has all the virtues of a classical e+e- trigger in a much more challenging environment

    • Store and analyze the data efficiently

    • Find New Physics

    D. Hitlin Super B Factory Trigger Workshop


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