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						Version 6.00
						Latest update:  11/14/94

Physics Triggers
________________

Benchmark physics processes are needed to study tracking and
calorimetric trigger efficiencies for the TDR.

This note has three parts:  a list of general physics processes, a list
of tasks associated with each one, and a partial list of what has
already been done.  Please help fill in the holes and correct any errors.

Note that the *BENCHMARKS* are a small subset of the physics processes
and that the list of physics processes is necessarily incomplete.
The intention is that benchmarks reflect trigger properties of all other
processes.  Simulation of the benchmarks need be finished in time for TDR.

There are two natural deadlines for looking over this list:
  October 11	for Trigger and Physics & Simulation group meetings at Pisa
  November 4	for Electronics group meeting at SLAC
Benchmarks and Monte Carlos need to be in good shape before the Pisa meeting.

Here is a flavor of the types of physics triggers considered:

	Global:  DC .or. EM

	  DC:
	    1.5 isolated charged tracks - pa > 200 MeV/c, pb > 125 MeV/c
	    1.5 isolated charged tracks - pa > 400 MeV/c, pb > 125 MeV/c
	  where p refers to pxy,
	  where A tracks reach outer layers, B and C tracks reach middle DC,
	  and where loopers have pxy < 260 MeV/c (mu, pi) < 300 MeV/c (e)
	  See BaBar Note # 162

	  EM:
	    2 isolated clusters (50 blocks) - E1 > 150 MeV, E2 > 150 MeV
	    2 isolated clusters (50 blocks) - E1 > 400 MeV, E2 > 150 MeV
	  where minimum ionizing mu- deposits 200 MeV/33.5cm, width (+40 -5)MeV
	  and where mu- need pxy > 240 MeV/c to reach the EM barrel
	  See BaBar Notes #133 and # 162

	Other global, DC and EM triggers could be used to reduce high rates.

	For example, during high backgrounds may run

	Global:  (DC .and. EM) .or. (DC .or EM)/10 prescaled

I.  Processes

	A.  B physics at the Upsilon(4S) - CP channels
	B.  B physics at the Upsilon(4S) - non-CP
	C.  B physics at the Upsilon(5S)
	D.  Charm physics
	E.  Tau physics
	F.  Two-photon physics

	G.  Bhabhas
	H.  Mu pairs
	I.  Cosmic rays

II.  Tasks ordered in increasing level of detail

	1.  Identification of explicit benchmark event modes
	  a)  Identification of physics modes and tags
	  For example, (B0 --> psi K0s) + (B0~ --> mu- nu_mu~ X)
	  b)  Trigger benchmarks as subset of identified modes
	  For example, (tau --> mu nu nu) could cover (tau --> e nu nu) as well
	  c)  Classify trigger efficiency requirement
		EFF - Efficiency precision measurement for physics
		HIE - High efficiency for physics
		LUM - Luminosity precision measurement
		CAL - Calibration of detector
		MON - Monitor beam conditions
	  For example, a high-precision BR measurement may be:
		(tau --> e) + (tau --> e)			EFF

	2.  Monte Carlo generator for the benchmark mode
	  a)  A compiled version on unix, including SLAC RS6000
	  b)  A version installed into BEGET package
	  c)  Generator switches and/or code to access the relevant modes

	3.  Studies of the properties of the benchmark modes
	  a)  Trigger efficiency as a function of trigger quantities
	  For example, at the generator level, event efficiency versus
	  charged particle multiplicity, track momentum, cluster energy,
	  track phi isolation and cluster phi/theta isolation
	  b)  Trade-off between trigger efficiency (in 3a) and background rates
	  c)  Lowest-level (hardware) trigger efficiencies of the mode
	  d)  Trigger efficiencies after typical offline analysis cuts

III.  Status

	A.  B physics at the Upsilon(4S) - CP channels
	  1a. Identified modes:
		B0 --> pi+ pi-
		B0 --> pi0 pi0
		B0 --> rho pi
		B0 --> psi K0s
		B0 --> psi K0L
		B0 --> psi K* --> psi K0s pi0
		B0 --> D+D-
		B0 --> D*+D*-
		B0 --> D0 K+ (where D0 is a CP state)
	      Accompanied by any of these tagging modes:
		B0~ --> (one and only one detected Kaon) X
		B0~ --> e nu X
		B0~ --> mu nu X
	  1b. Benchmarks:
		(B0 --> pi+ pi-) + (B0~ --> mu nu X)		HIE
		(B0 --> psi K0L) + (B0~ --> mu nu X)		HIE
	  2.  MC generator
		a,b) Exists in BEGET
		c)   Switches exist except for CP states (pi0 pi0) and (D0 K+)
		     Official code needed to select Kaon tags
	  3.  Trigger efficiencies:		Benchmarks done

	B.  B physics at the Upsilon(4S) - non-CP
	  1a. Identified modes:
		B --> rho l nu
		B --> pi l nu
		B --> D*+ l nu --> (K pi)pi+ l nu
		B --> D*0 l nu --> (K pi)gamma l nu
		B --> phi K
		B --> gamma gamma
		B+ --> tau nu_tau
	      Accompanied by (B~ --> X)
	  1b. Benchmarks:
		(B+ --> tau nu_tau) + (B~ --> X) 		HIE
	  2.  MC generator
		a,b) Exists in BEGET
		c)   Switches:			Not done
	  3.  Trigger efficiencies:		Not done

	C.  B physics at the Upsilon(5S)
	  1a. Identified modes:
		B0s --> rho K0s
	      Accompanied by any of these tagging modes:
		B0s~ --> (one and only one detected Kaon) X
		B0s~ --> e nu X
		B0s~ --> mu nu X
	  1b. Benchmarks:
		(B0s --> rho K0s) + (B0s~ --> mu nu X)		HIE
	  2.  MC generator
		a,b) Exists in BEGET
		c)   Switches:			Not done
	  3.  Trigger efficiencies:		Not done

	D.  Charm physics
	  1a. Identified modes:
		Ds --> mu nu X
		D --> pi l nu
		D --> rho l nu
	      Accompanied by D~ --> X
	  1b. Benchmarks:
		(D --> pi l nu) + (D~ --> X)			???
	  2.  MC generator
		a,b) Exists in BEGET
		c)   Switches:			Not done
	  3.  Trigger efficiencies:		Not done

	E.  Tau physics
	  1a. Identified modes:
		(tau- --> pi-) + (tau+ --> pi+) [spin correlations]
		tau- --> e- nu~ nu
		tau- --> mu- nu~ nu
		tau  --> K*(890) K nu
		tau- --> 3pi- 2pi+
		tau- --> 2pi- pi+ 2pi0
		tau- --> K K pi
		tau- --> K pi pi
		tau- --> some number of pi (where number = 3 to 6)
		tau  --> eta pi nu					(rare)
		tau  --> omega pi nu axial-vector			(rare)
		tau  --> K1_B nu, K1_B --> K1(1270, 1400) --> K pi pi	(rare)
		tau  --> gamma mu					(rare)
		tau  --> gamma e					(rare)
		tau  --> 3 charged leptons (eee, eemu emumu mumumu)	(rare)
		tau  --> (e or mu) (two pseudoscalar mesons)		(rare)
		tau  --> (e or mu) (one vector meson)			(rare)
		tau  --> proton X					(rare)
	      Accompanied by any of these tagging modes:
		tau+ --> e+ nu nu~
		tau+ --> mu+ nu nu~
		tau+ --> 2h+ h- X (h is any hadron)
	  1b. Benchmarks:
		(tau- --> 3pi- 2pi+) + (tau+ --> mu+ nu nu~)	HIE
		(tau- --> e-) + (tau+ --> mu+)			EFF
		(tau- --> pi-) + (tau+ --> pi+)			HIE
		(tau- --> K*(890) K) + (tau+ --> mu+)		HIE
	  2.  MC generator
		a,b) Exists in BEGET (KoralB) except
			rare decays		Not done
		c)   Switches:			Not done
	  3.  Trigger efficiencies:		Not done
	  3c. Hardware trigger efficiencies:	Partially done

	F.  Two-photon physics
	  1a. Identified modes:
		gamma gamma --> h+ h-	(W > 2 GeV)
		gamma gamma --> h0 h0	(W > 2 GeV)
		gamma gamma --> hadron resonance (W > 1.5 GeV)
		gamma gamma* --> spin-1 resonance --> hadrons (W > 1.2 GeV)
	  1b. Benchmarks:
		gamma gamma --> pi+ pi-	(W > 2 GeV)		EFF
		gamma gamma --> pi0 pi0	(W > 2 GeV)		EFF
		gamma gamma* --> 1++(1420) --> K K pi (e tag)	???
	  2.  MC generator:			Not done
	  3.  Trigger efficiencies:		Not done

	G.  Bhabhas
	  1a. Identified modes
		e+ e-
		e+ e- gamma
	  1b. Benchmarks
		both electrons in detector			LUM CAL
		one electron in endcap				CAL MON
		both electrons in luminosity tagger (if exists)	LUM MON
	  2.  MC generators
		a)  Exist  (BBBREM, BHLUMI for very small angles)
		b,c) BEGET and switches		Not done

	H.  Mu pairs
	  1a. Identified modes
		mu+ mu-
		mu+ mu- gamma
	  1b. Benchmarks
		mu+ mu-						LUM CAL
	  2.  MC generator exists in BEGET with switches (KoralB)
	  3.  Trigger efficiencies:		Not done

	I.  Cosmic rays
	  1a. Identified modes
		mu
	  1b. Benchmarks
		mu						CAL
	  2.  MC generator exists in BEGET with switches (HemiCosm)
	  3.  Trigger efficiencies:		Not done (need per subdetector)