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 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

6 6 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 ) <

7 7 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

8 8 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

9 9 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

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. With headroom, therefore, we must 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 are not 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