1 1 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 David Hitlin Caltech December 3, 2004

2 2 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Physics objectives of a Super B Factory The physics objectives of an experiment at a Super B Factory revolve around the search for New Physics. The specific approaches fall into several distinct categories Improvements in the classic unitarity triangle-related measurements to 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 A CP, A FB Kinematic distributions

3 3 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 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 The rest of the event is the other B, whose four-momentum is known ub You have a single B beam, with reduced systematics in V cb, V ub studies, and reduced backgrounds for rare decays, especially those involving neutrinos or photons e-e- D*D*D*D* p e+e+ B reco B recoil XuXu n Semileptonic decays B  D (*) n, B  ( p,r ) n, B  X c,u n …… ( ) B  D (*) tn ( sensitive to New Physics ) B  D (*) tn Purely leptonic decays B  tn, …. B  K nn B  invisible B  X s g

4 4 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Measurement precision – angles of the Unitarity Triangle Unitarity Triangle - Angles e + e - Precision1 Year Precision Measurement3/ab10/ab50/abLHCbBTeV a (pp) ( S pp, B  pp BR’s + isospin) 6.7  3.9  2.1  a ( rp ) (Isospin, Dalitz) (syst  3  ) 3, 2.3  1.6, 1.3  1, 0.6  2.5  -5  44 a ( rr ) (penguin, isospin) (stat+syst) 2.9  1.5  0.72  b (J/  K S ) (all modes) 0.3  0.17  0.09  0.57  0.49  g (B  D (*) K) (ADS) 2-3  ~10  <13  g (all methods)  Theory: a ~5%, b ~ 1%, g ~0.1%

5 5 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Probes of new physics - I 1)Measure the CP asymmetry in modes other than that measure sin2 b in the Standard Model Precision of benchmark sin2 b in can improve to the  1% level Expect the same value for “sin2 b ” in “, but different SUSY models can produce different asymmetries A great deal of luminosity is required to make these measurements to meaningful precision

6 6 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Extrapolated statistical errors on CP asymmetries 10 to 50 ab -1 are required for a meaningful comparison Current precision B A B AR measurement errors

7 7 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Measurement precision – rare decays Rare Decays – New Physics e + e - Precision1 Year Precision MeasurementGoal3/ab10/ab50/abLHCbBTeV G( b  d  / G (b  s  -- B( B  D ( * ) tn )SM: B : 8x %5.6%2.5%-- B( B  s nn ) (K -,0, K* -,0 ) 1 exclusive mode: ~4x10 -6 ~3 s -- B( B  invisible) <2x10 -6 <1x10 -6 <4x B( B d  mm ) B( B d  tt ) ---- B(t  mg ) <

8 8 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Rare Decays – New Physics – CPV e + e - Precision1 Year Precision MeasurementGoal3/ab10/ab50/abLHCbBTeV S(B0fKS)S(B0fKS) SM: <0.25%16%8.7%3.9%16 ??7 ?? S(B0fKS+fKL)S(B0fKS+fKL) SM: <0.25%-- S(Bh'Ks )S(Bh'Ks ) SM: <0.3%5.7%3%1%-- S(BKsp0)S(BKsp0) SM: <0.2%8.2%5%4% (?) -- S(BKsp0g)S(BKsp0g) SM: <0.1%11.4%6%4% (?) -- A CP (b  s g) SM: <0.5%2.4%1%0.5% (?) -- A CP (B  K* g ) SM: <0.5%0.59%0.32%0.14%-- CPV in mixing (|q/p|) <0.6% -- Measurement precision - rare B decays

9 9 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Rare Decays – New Physics e + e - Precision1 Year Precision MeasurementGoal3/ab10/ab50/abLHCbBTeV G( b  d  / G (b  s  -- B( B  D ( * ) tn )SM: B : 8x %5.6%2.5%-- B( B  s nn ) (K -,0, K* -,0 ) 1 exclusive mode: ~4x10 -6 ~3 s -- B( B  invisible) <2x10 -6 <1x10 -6 <4x B( B d  mm ) B( B d  tt ) ---- B(t  mg ) < Measurement precision – rare decays Masiero, Vempati, Vives t  mg is sensitive to 23 generation mass insertions, (analogous to b  ss s ) but in the lepton sector

10 10 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Mass insertion approximation: model-independent f K S B A B AR (now) f K S 30 ab -1 The scale of New Physics Ciuchini, Franco, Martinelli, Masiero, & Silvestrini f 23 mass insertion f 13 mass insertion D A CP (J/  K S - p 0 K S ) D A CP (J/  K S - f K S )

11 11 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 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, A CP, B to invisible, etc. Sensitivity to rare t decays A trigger that can do this will manifestly provide a large sample of D decays as well

12 12 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 The “Snowmass Year” was defined in 1988, based on data from CESR/CLEO: 1 Snowmass Year = 10 7 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/B A B AR and KEK-B/Belle, and the advent of trickle injection, the modern B factory Snowmass Year constant is 1.4 x 10 7 Thus we can integrate 10 ab -1 /year with 7 x cm -2 s -1, instead of with cm -2 s -1 The New Snowmass Year

13 13 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Occupancy extrapolations are uncertain, but sobering 2x x % 2x x Now: 8 physics clusters

14 14 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Tracking will have to be done with silicon, not gas We will have to develop a silicon tracking trigger

15 15 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Top module

16 16 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Bottom module

17 17 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Midplane module 574%

18 18 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 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

19 19 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 There is a fast, rad hard replacement crystal for CsI(Tl)

20 20 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Comparison of CsI(Tl), LSO, Liquid Xe CsI(Tl)LSOLXe Atomic number Z54 effective65 effective54 Atomic weight A131 Density (g/cc) Radiation length (cm) Molière radius (cm) l scint (nm) t scint (ns) 680, , 22, 45 Light yield (photons/MeV)56,000 (64:36)27,00075,000 Refractive index Liquid/gas density ratio519 Boiling point at 1 atmosphere (K) 165 Radiation hardness (Mrad) Cost/cc3.2>7 (50 ???)2.5

21 21 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004

22 22 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 An upgrade path from B A B AR to Super B A B AR BABAR 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 EMC  Liquid Xe scintillation or fast, rad-hard crystals (LYSO) + New trigger and DAQ system DIRC  Faster, pixelated readout

23 23 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 Projections depend heavily on the luminosity term Cross sections: B B : 1 nb  B B pairs/year uds : 1.6 nb, c : 1 nb leptons (  ): 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 At 7x10 35, 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

24 24 D. Hitlin Super B Factory Trigger Workshop Dec. 2/3, 2004 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