Charm Physics at Super B Factories after BESIII, Belle and B A B AR David Hitlin The Future of Heavy Flavor Physics ITEP, Moscow July 24, 2006

2 David Hitlin ITEP Meeting July 24, 2006 Charm Physics - What is to be done ?  The current state of the art in charm physics is CLEO-c, which will compile ~.75/fb per physics objective  BESIII will extend the data sample to ~20/fb  It is beyond a cliché to point out that a B Factory is also a  /charm or Flavor Factory  Thus a Super B Factory is also a Super /charm or Super Flavor Factory  B A B AR and Belle have already produced many very interesting results in charm physics  A Super B Factory can increase the data by 50 to 100  There is a strong motivation to do so for B decay studies  CP asymmetries, BR, and kinematic distributions in rare B decays, primarily those involving  Is there a similar motivation to do so for charm (or ) studies?

 The question then naturally arises as to whether the  and charm data that a Super B factory would acquire in the 10 GeV region is sufficient, or whether it is interesting to take data in the GeV region as well?  That is, are there specific physics topics that substantially benefit from threshold kinematics?  Are these objectives important enough to warrant the expense and running time taken from high energy running?  If there are such topics, what is the impact the design of a Super B Factory to allow it to run at lower CM energies?  In this context, a small group of SuperB adherents, most with  /charm experience, has been looking into this question John Back, Jose Bernabéu, Marcello Giorgi, David Hitlin, Antimo Palano, Frank Porter, Patrick Roudeau 3 David Hitlin ITEP Meeting July 24, 2006

Impact on SuperB design of low energy capability  Conventionally, for an e + e - collider: for a given tune shift, if below the RF power limit Use of wigglers is required to increase emittance, raise luminosity  The low emittance SuperB design under study for Tor Vergata has a different tune shift limit behavior and may therefore have a different energy dependence for the luminosity  Cost of low energy capability  Extra wigglers (?)  Running time lost to B physics  Savings on power David Hitlin ITEP Meeting July 24,

Working assumptions  CLEO-c:.75 fb -1 at  (3770) and.75 fb -1 at  (4170) by 2008  BESIII: 20 fb -1 at  (3770) and 12 fb -1 at  (4170) (8 years) (BEPCII does not have enough energy to produce charmed baryons)  B A B AR +Belle: 2 ab -1 total in ~2009  SuperB at (and below) E cm =10.58:  =10 36 : 1 year: 15 ab -1 5 years: 75 ab -1 in 4 GeV region:  ~few x : 1 month/year: fb -1 /topic We use an updated Snowmass Year: 1.5x10 7 sec (was 10 7 sec), based on PEP-II/BABAR and KEK-B/Belle experience (trickle injection, highly reliable detectors) 5 David Hitlin ITEP Meeting July 24, 2006

If low energy running proves desirable  It is unlikely that a Super B Factory would spend a large period of time running at low energies  A potentially realistic running strategy:  Assume a Super B Factory runs 10 months/year  9 months with  =10 36 at the (4S), producing =13.5/ab  1 month (includes tuneup) in the GeV region, at  =1.3 to 2.2 x 10 35, producing ~120 to ~200/fb in each run, with the running time divided between:  (3770),  (4040),  (4160),  (4XXX), charmed baryons,  running at 4.24 ……. David Hitlin ITEP Meeting July 24,

Super B Factory sample sizes E cm (GeV)    (nb)  (cm -2 s -1 ) 1.6 x  pairs per Snowmass year 8.4x10 8 (1 month) 1.34x10 10 (9 months) E cm (GeV)  DD or cc (nb) 6.34  (cm -2 s -1 ) 1.3 x DD (cc) pairs per Snowmass year 1.2x10 9 (1 month) (DD) 5x10 9 (9 months) (cc) 7 David Hitlin ITEP Meeting July 24, 2006

Charm production cross section   (nb ) 8 E CM (GeV)

 Cross sections are large  Can use “off peak” data  Very high statistics (~1.4 x 10 6 D’s / fb -1 ). Also:  Continuum production above and below 4S.  B decays – allow measurement of absolute  ’s, and, perhaps, spins ?  D tagging - ~10 7 reconstructed D’s.  Can study charm baryons  ISR events  , - events Charmed hadron production at B Factories? On Off E CM (GeV) 9 David Hitlin ITEP Meeting July 24, 2006

10  Charmed mesons  Absolute branching fractions  CKM physics  Dalitz plots  Rare decays  DD mixing  CP violation  Charmed baryons   c Absolute Branching Fractions  Form factors  Precision R scan  Charmonia  Study of J/ ,  ’,  cj  Y(4260),  (4160),  (4040)  Search for charmonium hybrids Charm physics opportunities Which topics are better addressed at Ecm~4 GeV, and which at ~10 GeV ? David Hitlin ITEP Meeting July 24, 2006

11  QCD tests +  s  Non-strange spectral function (much better resolution!)  Strange spectral function (real measurement, v/a, … )  Second class currents  Chiral perturbation theory  Exclusive decays  Branching ratios  Light meson spectroscopy  Michel parameters  lifetime – universality tests  V us from inclusive decays  CP violation in  production and decay  Rare decays LFV  Neutral current couplings   mass  physics opportunities Which topics are better addressed at Ecm~4 GeV, and which at ~10 GeV ? David Hitlin ITEP Meeting July 24, 2006

Methodology  A first order comparison of measurement capability can be made by scaling from existing data sets  For example, for rare decays with little or no anticipated background, scaling is done as  When background is expected, scale by  Systematic limits must also be considered  With high statistics, can trade statistics for reduced systematic errors, but this is difficult to estimate with any degree of precision  In some rare decay cases, naïve scaling by sample size may favor high energy, but background may be better at the  (3770)  Near threshold, use of m ES improves resolution over m inv, improving background rejection 12 David Hitlin ITEP Meeting July 24, 2006

Exclusive production at the  (3770)  Exclusive DD with E D = E beam   (DD) = 6.4 nb  Low multiplicity ~ 5-6 charged particles/event  High tagging efficiency: ~22%, (~0.1% at the  (4S) ) CLEO-c 100 pb  (3770) yields the same number of fully reconstructed events as 500 fb  (4S) David Hitlin ITEP Meeting July 24, Absolutely normalized hadronic, leptonic and semileptonic decays

Rare Charm Decays – FCNC and LFV Due to the large mass difference between up type quarks, the GIM mechanism suppresses short distance FCNC more for up type quarks than for down type quarks The lepton flavor-violating mode is strictly forbidden. New Physics may enhance FCNC and LFV, e.g., R parity violating SUSY: Burdman et al. Best limits are from BABAR SM: 14 David Hitlin ITEP Meeting July 24, 2006 Leptonic

Leptonic decays  Calibration of lattice QCD, search for FCNC 0.6% (e-6,e-7)0.6% e-8 e-8 e-8 Process CLEO-c BESIII 4GeV BABAR+Belle SuperB SuperB 1 month final 1 year 5 years 15 David Hitlin ITEP Meeting July 24, 2006 What does precision of lattice QCD calculation require of experiment?

Semileptonic heavily GIM suppressed: BF( c  ull )~10 -8 New physics can introduce new particles into the loop: Some New Physics models increase  (c  ull) to —10 -5 Potentially measurable! Charm decays via FCNC 16 David Hitlin ITEP Meeting July 24, 2006

17 Charm FCNC Branching Fraction Limits P. Jackson, Charm 2006  (fb -1) BF Limits BABAR x SuperB – 18 x David Hitlin ITEP Meeting July 24, 2006 Upper limits on BF (x10 -6 ) at 90% CL (preliminary)

18 D 0 Dalitz plot examples John Back David Hitlin ITEP Meeting July 24, 2006 CLEO II.V: D. Cronin-Hennessey et al. PR D (2005)

CLEO II.V: D. Cronin-Hennessey et al. PR D (2004) 19 David Hitlin ITEP Meeting July 24, 2006

CLEO II.V Comparison of Dalitz plots for 20 David Hitlin ITEP Meeting July 24, /pb 91.5/fb

21 D branching fractions Frank Porter BABAR or Belle BABAR+Belle final SuperB 1 year SuperB 5 years David Hitlin ITEP Meeting July 24, 2006

22 D branching ratios Frank Porter David Hitlin ITEP Meeting July 24, 2006 Normalization relative to decays whose absolute BR’s can be measured at low energy Statistical errors only

23 D 0 mixing, CP violation Frank Porter David Hitlin ITEP Meeting July 24, 2006 n.b. extrapolations include statistical errors only

mixing  Achieving sensitivity at the level requires distinguishing wrong sign decays due to mixing from DCSD decays  Rate of wrong sign decays  Measurement of time dependence is crucial (  10GeV)  However, need to know   At the  (3770) can use quantum correlations between fully reconstructed D decays to determine   At 10 GeV can determine  by measuring related DCSD modes (requires K 0 modes) 24 David Hitlin ITEP Meeting July 24, 2006

mixing comparison Process CLEO-c BESIII 4GeV BABAR+Belle SuperB SuperB 1 month final 1 year 5 years 0.15% 0.06% 0.01% Statistical errors only 25 David Hitlin ITEP Meeting July 24, 2006 David Asner

J P =3/2 + (L=0) J P =1/2 + (L=0) Strangeness Charm Isospin Charmed baryon states  |C| = 1:  L=0 Ground State – almost full: J P =1/2 +: {6} qq  c (2455),  c (2470),  c (2698)All seen J P =1/2 +: {3} qq  c (2285),   c (2575)All seen J P =3/2 +: {6} qq  c (2520),  c (2645), ??All but  c *  L>1 – filling up ? J P =1/2 -:  c (2593),  c (2790), … J P =3/2 -:  c (2625),  c (2815), …  Several more new states from BABAR and Belle … and more No J P have yet been measured … from CLEO II  (or  ) c (2880),  (or  ) c (2765) ?? 26 David Hitlin ITEP Meeting July 24, 2006

Λ c (2940) + : M = (2939.8±1.3±1.0) MeV/c 2 Γ = (17.5±5.2±5.9) MeV First Charm Baryon  Charm Meson  c (2940) Λ c (2880) + Λ c (2940) + D 0 mass sidebands Wrong sign D 0 p 287 fb -1 hep-ex/ Observed in cc continuum production in D 0 p decay mode (D 0  K -  +, K -  +  -  + ) New data on Λ c (2880) + : New Decay Mode  D 0 p BABAR: M = (2881.9±0.1±0.5) MeV/c 2 Γ = (5.8±1.5±1.1) MeV PDG: ( “ Could be  c ” ) M = (2880.9±2.3) MeV/c 2 ; Γ < 8 MeV 27 David Hitlin ITEP Meeting July 24, 2006

Charmonium hybrids  Charmonium hybrids are expected to exist in the mass range 2.8 – 5 GeV  Decays of higher mass  resonances in the GeV may be an excellent source of charmonium hybrids   ( ) cross section ~ 10nb  Assume hybrids are produced in of decays  Then in a 1 month run at SuperB: Decay mode RateEfficiencyVisible fraction Events observed (x 10 3 ) David Hitlin ITEP Meeting July 24, 2006 Antimo Panalano

Conclusions  There will be several areas of real interest in charm (and  ) physics remaining after BESIII completes data-taking  Several charm measurements require running near charm threshold  These are typically Standard Model calibration or engineering measurements  Absolute hadronic, leptonic and semileptonic branching fractions  Pseudoscalar coupling constants  Measurements of  in correlations  Charmed baryon studies (abs.  )  Charmonium hybrid searches  Some of these measurements can also be done well in the (4S) region  Most New Physics-related measurements are better done in the (4S) region 29 David Hitlin ITEP Meeting July 24, 2006

Conclusions, continued  A low energy program at a Super B Factory could be developed by “stealing” one month per year from the primary B physics program  It is possible to do so at some (small) capital cost, which would be partly offset by power savings  Whether this is worth doing or not depends to some extent on the state of New Physics explorations at the LHC, on the accomplishments of BESIII, and on the progress of lattice QCD  Whether or not a Super B Factory has low energy running capability, it will produce significant new results in  and charm physics 30 David Hitlin ITEP Meeting July 24, 2006