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Exploring Physics Objectives and Trigger Requirements for the Super B Factory

This document outlines the key physics objectives for experiments at a Super B Factory, focusing on the pursuit of New Physics through precise measurements and advanced recoil physics techniques. Essential approaches include refining the unitarity triangle measurements, leveraging lepton tagging to minimize systematic errors, and increasing sensitivity to rare decays such as B, D, and t decays. The necessity for open triggers and large unbiased samples for B decay analysis is emphasized, along with the importance of novel silicon tracking systems for data collection.

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Exploring Physics Objectives and Trigger Requirements for the Super B Factory

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  1. Physics Requirements for a Super Factory Trigger B David Hitlin Caltech December 3, 2004 D. Hitlin Super B Factory Trigger Workshop

  2. 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

  3. 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

  4. Measurement precision – angles of the Unitarity Triangle Theory: a ~5%, b ~ 1%, g ~0.1% D. Hitlin Super B Factory Trigger Workshop

  5. 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

  6. 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

  7. Measurement precision – rare decays D. Hitlin Super B Factory Trigger Workshop

  8. Measurement precision - rare B decays D. Hitlin Super B Factory Trigger Workshop

  9. 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

  10. 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

  11. 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

  12. 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

  13. 1036 7x1035 2x1035 20% 1036 7x1035 2x1035 Now: 8 physics clusters Occupancy extrapolations are uncertain, but sobering D. Hitlin Super B Factory Trigger Workshop

  14. 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

  15. Top module D. Hitlin Super B Factory Trigger Workshop

  16. Bottom module D. Hitlin Super B Factory Trigger Workshop

  17. Midplane module 574% D. Hitlin Super B Factory Trigger Workshop

  18. 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

  19. There is a fast, rad hard replacement crystal for CsI(Tl) D. Hitlin Super B Factory Trigger Workshop

  20. Comparison of CsI(Tl), LSO, Liquid Xe D. Hitlin Super B Factory Trigger Workshop

  21. D. Hitlin Super B Factory Trigger Workshop

  22. 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

  23. 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

  24. 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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