Physics reach of a Super B-Factory Riccardo Faccini Universita’ “La Sapienza” e INFN Roma CSNI, 4 Febbraio 2003

Motivations PEP-II/B A B AR and KEK-B/Belle have provided the first evidence that the CKM phase is indeed the source of CP violation in B meson (and, by extension) K meson weak decays Since the matter-antimatter asymmetry of the universe cannot be accounted for by Standard Model CP violation, we had a reasonable expectation that the Standard Model would fail this unique test The Standard Model passed the test The unitarity triangle construction is self-consistent It is now time to test the higher orders (loops) and this requires a luminosity of cm -2 s -1 Overconstrain the unitary triangles with much smaller errors Study decay distributions of loop dominated, rare, decays

How high the luminosity?!? today SuperBFactory (SBF)

New physics and flavor physics CP violation is an excellent probe of new physics: The CKM mechanism has a single source of CPV and makes quantitative predictions New sources of flavor and CP violation can induce large deviations from the Standard Model predictions, many of which are not obscured by hadronic uncertainties Henceforth in this discussion, I will use the supersymmetric SM :The supersymmetric SM has 124 independent parameters, 44 of which are CP-violating SBF can probe the CP violating part of Susy and resolve the ambiguities in the new particles zoology

High precision B physics involves reducing the systematic errors It can be achieved at expense of stat error. Fully reconstruct one B and look at the recoil in an inclusive way  4 M Bs /ab -1 (  ~0.2%) Advantages: All the remaining tracks come from the other B possibility to apply partial reconstruction (e.g. B  D *   (D 0 )  s  in a clean way Heavily used in sys error reduction in the following Physics with single B-beams ?

Recoil physics is cleaner Inclusive lepton analysis Single-B beams V ub V cb B  Xl

Precision Measurement of the sides of the Unitary Triangle CKMAnalysis  stat (2007) %  stat (2011) %  sys (2011)%  th (>2010) % V cb D (*,**) l b  cl V ub b  ul B  X u l V td Md*Md* V ub,V td B  5% on V ub ?  M d /  M s would be more interesting but not doable by Y(4S) SBF

rrr Precise measurement of the angles: impact of SUSY MSSM phase SM phase Ratio of amplitudes in SM Ratio of MSSM/SM amplitudes

Precision Measurement of the angles :  Sys err Sys err lepton tags (stat err. ~70% larger) Only J/  K s will be syst. Limited, but one can use only the cleaner tags to reduce the error. All comparisons still stat. Limited.

Precision Measurement of the angles :  22  ’’  (sin2  eff ) ~ 0.03 in 10 ab -1 with 2  eff = 2  Current precision on A CP (B 0  p + p - ) yields Isolating penguin pollution requires measurement of tagged and decay branching fractions, which can only be done at a B Factory L = 10 ab -1  (rad) L = 2 ab -1 … but there is a 4-fold ambiguity! (revert triangle and    )

2ab -1, actual detector r sin 2  0.3   0.2   0.1unreliable Crucially depends on r (breaks down for r < 0.1?) 8-fold ambiguity spoils the extraction of  But A CP = 2r sin  sin  is accessible:  (A CP ) ~ 0.03 with 2 ab = f - + ( , , r) )( )( 0 +     KDB KDB )( )( 0 -     KDB KDB )( )( 0 -     KDB KDB )( )( 0 +     KDB KDB - - = f = f = f + + Measure:  2 A (B -  D 0 + K - ) = A (B -  D 0 K - ) + A (B -  D 0 K - ) Precision Measurement of angles : 

Precision Measurement of the angles :  Interference between Vcb and Vub diagrams in b  cud transitions exploited to measure sin2  The biggest limitation comes from the knowledge of the amplitude of oscillations (~0.02). Theoretical uncertainty ~30% Initial idea involved only B 0  D (*) , now extended to B 0  D (*) ,a 1,K s This reduces th. Error Expected asymptotic error  ~0.05 b c W d  u  d d D  b u W  c D (  d d d

Expected Errors 1 year of SBF  (sin2  )~0.008  (sin2  eff )~0.032  (BR(  0  0 ))~6%  (  (DK))~2 o  (sin(  ))~0.05

Rare decays and New Physics: b  s  single-B beams reduce the model dependence and allow time dependent measurements. B.F., CP asymmetries sensitive to NP. B  direct CP asymmetry and Br(  )/Br(K *  ) sensitive to MSSM B  X s ll CP asymmetry small in SM and large in MSSM B  ll BF are very small, but could become non negligible with NP contributions B  l relative ratio of the channels (l=  vs l=  )

CPV in exclusive radiative decays

Probe SUSY in K * ll M 2 ll (GeV 2 )

Comparison on rare decays

Super-BF: design considerations Change boost to optimize cost/physics Smaller lifetimes  continuous injection More and shorter bunches X-ing angle ~ 1.5 mrad (impact on backgrounds) Redesign HER lattice Focussing Magnets closer to I.P. to get smaller  functions Vacuum system will have to dissipate 16 KW/m of syncrotron radiation RF system, same as B-Factory but scaled up 1 O.o.M. Cost of power, 100 times higher than now Planned workshops: –February 2003: SBF Workshop –October 14-17, 2003 SLAC: ICFA Workshop on e+e- Factories

Super B-Factory % B-Factory Beame+e- e+ E(GeV) #bunches lifetime (min)75200 Current (A)  * (mm) x=15/y=1.5x=450/y=10 Emittance(nm)x= 44/y=0.4440/2.5 Beam spot (  m) x= 81/y=0.8x= 147/y=5 Tune shift

Boost optimization Normalized luminosity degradation factor

Lifetime details Luminosity: interacting particles get lost Vacuum: beam-gas scattering Touschek: intra-beam scattering Beam-beam: optimize tune shifts Dynamic aperture: due to beta functions

Injection details

Interaction region With increasing luminosity beam beam interactions increase wrt syncrotron radiation/vacuum loss  extrapolations from PEP very rough X-ing angle Close Q1

Super BaBar: detector issues Background considerations will drive detector design. The vacuum/luminosity background should be ~600 larger than PEP, but other sources should take place. Radiation resistant and fast  smaller Smaller detector  higher magnetic field Crucial point is the calorimeter (sensitivity to background &     reconstruction). Trigger rates: LV1 ~ 100KHz ; 5GB/s LV2 ~ 6Khz; 300 MB/s Computing ~50 times more challenging than BaBar Will have to wait for better machine design before being able to make detector strawman

Calorimeter design choises

A potential upgrade path from B A B AR to Super B A B AR DIRC IFR with same design New EMC – Liquid Xe, YAP, LSO? New tracker – Two inner pixel Layers Thin double-sided Si-strip arch layers New DIRC(s) with compact readout

Summary Physics case for SuperBaBar : precise measurements in the flavor sectors: Sensitivity to new physics : Probe CP violation parameters of new physics Resolve ambiguities in NP zoology Reduce systematics (e + e - machines more suited: single beam approach) Select high number of events in penguin dominated processes Workshop at SLAC March 2003 Design of SuperBFactory First set of parameters released in May Workshop in February 2003 Design of SuperBaBar Waiting for physics case and B factory Working group within BaBar will report by fall 2003