The Physics of SuperB - Experimental Detector requirements and physics performance required to achieve the physics goals David Hitlin INFN SuperB Review November 12, 2007

This talk will primarily address two topics: Design considerations for an appropriate detector for a 1036 collider like SuperB Note that detector technology issues for SuperB, a low-emittance, low current collider, are quite different from those for a high current machine such as SuperKEKB The physics goals are also different from those of BABAR/Belle How can we upgrade an existing detector (using BABAR as an example) to better match the new physics goals ? With such an upgraded detector, can we reach adequate levels of sensitivity to be relevant to the elucidation of the details the flavour sector of any new physics found at the LHC ? David Hitlin INFN SuperB Review Nov. 12, 2007

Primary physics objectives of a Super Flavour Factory Are there new CP-violating phases ? Are there new right-handed currents ? Are there new loop contributions to flavour-changing neutral currents Are there new Higgs fields ? Is there lepton flavour violation ? Is there new flavour symmetry that elucidates the CKM hierarchy ? What are the requirements for a detector that can address these questions in a 1036 asymmetric e+e- environment ? David Hitlin INFN SuperB Review Nov. 12, 2007

Doing the physics: environment and event characteristics The primary physics goals of SuperB differ from those of BABAR and Belle, which showed that the CKM phase is consistent with all known CP-violating phenomena and that the Unitarity Triangle could withstand a detailed series of over-constrained tests The SuperB physics goals are the next logical step, using rare heavy flavour decay phenomena as a sensitive probe of physics beyond the Standard Model The basic physics environment (e+e- annihilation from GeV) is familiar, but the physics objectives differ, and the luminosity of SuperB is increased by nearly two orders of magnitude over the current machines Thus the background environment is different and the trigger requirements differ from those of PEP-II/KEKB In what way do these differences reflect into the design of the SuperB detector? This talk will review the machine-produced environment and event characteristics and use several specific physics examples to arrive at a set of design criteria for the SuperB detector Specific design details will be presented in the following talks David Hitlin INFN SuperB Review Nov. 12, 2007

David Hitlin INFN SuperB Review Nov. 12, 2007 Trigger rates and DAQ Physics rate at 1036 are substantial Due to the low emittance design, machine backgrounds appear to be tolerable and a small radius beam pipe is feasible, allowing use of a reduced energy asymmetry Physics demands an open trigger as is traditional in e+e- Demands on the trigger and DAQ are thus substantial, but LHC-derived technologies are sufficient Further details in later presentations David Hitlin INFN SuperB Review Nov. 12, 2007

Choice of energy asymmetry Smaller SuperB beam sizes at the IP allow the use of a smaller beam pipe (radius 1 cm) This permits a thinner beam pipe in radiation lengths First track measurement at 1.2 cm Smaller asymmetry improves solid angle coverage 7x 4 GeV Boost bg=.28 PEP-II: bg =0.56 David Hitlin INFN SuperB Review Nov. 12, 2007

David Hitlin INFN SuperB Review Nov. 12, 2007

Solid angle coverage 7x4 GeV Solid angle (% of 4p) 200 300 600 400 500 D (%) 700 800 Forward coverage (mrad) Rear coverage (mrad) 7x4 vs 8x3.5 GeV Coverage of BABAR: 300 mrad forward 600-700 mrad backward David Hitlin INFN SuperB Review Nov. 12, 2007

Final state reconstruction efficiency In B meson decay <nch>=5, <ng>=5 t decay is dominated by 1 and 3 prong topologies We expect recoil physics to be an important part of the program Both B mesons must, perforce, be reconstructed In most, but not all cases, the object of photon detection is p0 reconstruction. Thus ~ eg2 The effective solid angle for complete final state reconstruction is determined by the system which has the minimum solid angle coverage evertex  etracking  ePID  eg  David Hitlin INFN SuperB Review Nov. 12, 2007

David Hitlin INFN SuperB Review Nov. 12, 2007 B0fKs reco efficiency vs solid angle coverage J. Back David Hitlin INFN SuperB Review Nov. 12, 2007

David Hitlin INFN SuperB Review Nov. 12, 2007 Track momenta and polar angle distribution David Hitlin INFN SuperB Review Nov. 12, 2007

David Hitlin INFN SuperB Review Nov. 12, 2007 Track momenta at lower Ecm are substantially softer SuperB can run at lower Ecm for specific D and t studies, as well as at the other U resonances (particularly U (5S) ) (with bg =0.28) 1 month of SuperB running at y(3770) or for below charm charm threshold yields 10X final BES-II data David Hitlin INFN SuperB Review Nov. 12, 2007

Center-of-mass energy spread Many analyses use cuts on m ES and DE to extract a signal Center-of-mass energy spread determines m ES and thus the signal-to-noise ratio in rare B decays Center-of -mass energy spread also determines the effective cross section on the U (4S) , U (5S) or y (3770) resonances This was a concern in earlier incarnations of SuperB which had highly disruptive collisions but is no longer an issue PEP-II, SuperB (4S) David Hitlin INFN SuperB Review Nov. 12, 2007

DE resolution p+p- D*p David Hitlin INFN SuperB Review Nov. 12, 2007

Recoil physics at the ¡ (4S) D* p e+ Breco Brecoil Xu n “The Recoil Method “ will be of increasing importance at SuperB Fully reconstruct one of the two B’s in hadronic modes and/or semileptonic modes as well .......and do it with high efficiency The rest of the event is the other B, whose four-momentum is known You then have a single B beam: reduced backgrounds for rare decay studies, especially those with neutrinos, and reduced systematics for precision Vcb, Vub studies Semileptonic decays B D(*)n, B (p,r)n, BXc,un B D(*)tn (sensitive to New Physics) Purely leptonic decays Btn, …. B Knn B invisible B Xsg David Hitlin INFN SuperB Review Nov. 12, 2007

The recoil method Subtract combinatorial background Breco (recoil) kinematics known with small uncertainties Breco (recoil) flavor determined Breco (recoil) charge (B0- B+ separation) Direct mX reconstruction Lepton charge – Breco (recoil) flavor correlation Kinematic constraints on recoil B Low efficiency - can be tuned for purity purity yield Xcn Xun sg Dtn p+n p0n tn p+tn Knn 10-2 10-1 1 10 Luminosity (ab-1) Number of recoil events Reconstructed B mesons 0 2 4 6 8 10 Luminosity (ab-1) David Hitlin INFN SuperB Review Nov. 12, 2007

Acceptance studies BKGD/Signal with smearing Many of the main physics objectives of SuperB involve missing energy signatures Detector requirements Use of the recoil technique Excellent reconstruction efficiency for hadronic B decays, especially those involving D*s Excellent particle ID Hermeticity Improving backward calorimeter coverage can pay large dividends in signal/background Study using Btn benchmark Forward polar angle coverage (radians) BKGD/Signal with smearing Backward polar angle coverage (radians) M. Mazur David Hitlin INFN SuperB Review Nov. 12, 2007

David Hitlin INFN SuperB Review Nov. 12, 2007 LFV in t decays: SuperB capability tg : the ultimate sensitivity will be affected by e+e-t+t-g t+tag t-  m-nng irreducible background. When that limit is reached, the sensitivity scales as 1/sqrt(L). For ~75/ab (SuperB @ 5 yrs) expect ~2x10-9 SM t decay (1- or 3- prong) (1 or 2 ) CM frame Signal decay LFV: no pmiss (MEC) ~9MeV  (E) ~50MeV David Hitlin INFN SuperB Review Nov. 12, 2007

LFV in t decays: SuperB capability t , hh’ : the sensitivity is not likely to be limited by irreducible backgrounds: the sensitivity scales as 1/L. For SuperB @ 5 yrs expect ~2x10-10 Principal backgrounds David Hitlin INFN SuperB Review Nov. 12, 2007

LFV in t decays: SuperB capability SuperB sensitivity directly confronts many New Physics models BABAR SuperB sensitivity For 75 ab-1 David Hitlin INFN SuperB Review Nov. 12, 2007

Limits are highly constraining (example tmg) David Hitlin INFN SuperB Review Nov. 12, 2007

Comparison to Snowmass Points and Slopes Argand and Herrero arXiv:0710.4091v1 [hep-ph] Lepton Flavour Violation in SUSY-seesaw: an update MSSM + three right-handed neutrinos + SUSY partners SPS-4 David Hitlin INFN SuperB Review Nov. 12, 2007

t  lll - LFV chiral couplings SuperB sensitivity to t  lll is an order of magnitude better than for t  mg : 2x10-10 Models predict a wide range of B(t  lll )/B( t  mg ): If t  lll is seen, it can, using polarized t’s, also be the key to studying the chiral couplings of the LFV physics David Hitlin INFN SuperB Review Nov. 12, 2007

Polarized t’s can probe the chiral structure of LFV (lll) Flipping the helicity of the electron beam allows us to ascertain the chiral structure of dimension 6 four fermion lepton flavor-violating interactions Dassinger, Mannell, et al. David Hitlin INFN SuperB Review Nov. 12, 2007 24

Polarization Longitudinally polarizing one or both beams allows a sensitive search for T violation in t production and/or CP violation in t decay Seeing either of these phenomena is a longshot, but one with a substantial payoff Longitudinal polarization of the electron beam is straightforward (was routine in SLC operation) Longitudinal polarization of the positron beam is an R&D project Luminosity enhancement t polarization David Hitlin INFN SuperB Review Nov. 12, 2007

The SuperB design has a longitudinally polarized e- beam Several techniques of achieving longitudinal e- polarization of >80% at the IP are discussed in the CDR (see later presentation) Provides polarization in the 10 GeV CM region, not at lower ECM Production of polarized positrons (~40%) is a substantial R&D project, and in fact, a potential area of synergy with ILC R&D SuperB plans only a polarized e-, which yields most of the physics benefits David Hitlin INFN SuperB Review Nov. 12, 2007

CP violation in t production and a t EDM With a polarized electron beam, can define an azimuthal asymmetry in hadronic t decays sensitive to to a t EDM : Summing over t+ and t- yields a true CP-odd observable Sensitivity: where Bernabeu et al. A three order of magnitude improvement over current bounds David Hitlin INFN SuperB Review Nov. 12, 2007

CP Violation in t decay Unpolarized t’s Measure B’s of t decays with two or more hadrons Interpretation of any observed CPV requires understanding of inelastic final state interactions Measure CP or T-violating correlations in t+t- decays Polarized t’s Search for T-odd rotationally invariant products, e.g. in t+ and t- decays such as Search for T-odd correlation between t polarization and m polarization in decay Sensitivity to asymmetries at the 10-3 level David Hitlin INFN SuperB Review Nov. 12, 2007

Tau magnetic dipole moment The polar angle distribution of t’s is sensitive to the t magnetic dipole moment It is necessary to understand the reconstruction efficiency as a function of polar angle to the 10-3 level by use of a control sample This level of understanding can already be demonstrated with in BABAR data: J.Bernabeu et.al hep-ph 0707.2496 With polarized e-, it is possible to separate the anomalous moment ff from the charge ff BABAR 75 (Data/MC) inefficiency (%) Polar Angle q (radians) BABAR Preliminary Reconstruction inefficiency (~1%) measurable with a 10% uncertainty Goals are achievable David Hitlin INFN SuperB Review Nov. 12, 2007

Extrapolated statistical errors on CP asymmetries BABAR measurement errors 50 ab-1 Current precision David Hitlin INFN SuperB Review Nov. 12, 2007

B g fK0 at 50/ab with present WA value J/yK0 fK0 David Hitlin INFN SuperB Review Nov. 12, 2007

David Hitlin INFN SuperB Review Nov. 12, 2007 Conclusions An excellent detector for SuperB can be constructed using an existing detector such as BABAR as a base Improved hermiticity is of prime importance, as is improved vertex detection, better muon ID, a much higher bandwidth DAQ system, and an improved trigger A polarized electron beam enables t EDM, CPV and anomalous moment measurements Polarization experiments impose no new requirements on the detector In fact, systematics due to detector inhomogeneity are reduced There is, of course, overlap with the programs of LHC flavour experiments such as LHCb, but the e+e- environment makes possible a substantial number of unique and important physics objectives, especially in those areas most sensitive to new physics, such as LFV, FCNC, decays involving (multi) neutrals, mixing, ….. The achievable levels of sensitivity in rare B and t decays allow substantial coverage in the parameter space of new physics High statistics flavour physics at an e+e- collider will likely provide information crucial to the understanding of new physics found at LHC David Hitlin INFN SuperB Review Nov. 12, 2007