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Prospects for Charm Studies at Super B

Prospects for Charm Studies at Super B. B. Meadows University of Cincinnati Representing Super B. Prospects for Charm at Super B. Super Flavour Factories Charm Mixing CP Violation Reach Rare Decays of D Mesons Summary. 2. Prospects for Charm at Super B. Super Flavour Factories

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Prospects for Charm Studies at Super B

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  1. Prospects for Charm Studies at Super B B. Meadows University of Cincinnati Representing Super B

  2. Prospects for Charm at Super B Super Flavour Factories Charm Mixing CP Violation Reach Rare Decays of D Mesons Summary 2

  3. Prospects for Charm at Super B Super Flavour Factories Charm Mixing CP Violation Reach Rare Decays of D Mesons Summary 3

  4. Super Flavor Factories Next generation of e+e- machines with L~100 x B factories Able to measure effects of New Physics (NP) on the decays of heavy quarks (b and c) and of the  lepton Should allow a timely check on the pattern of flavour and helicity dependencies of the couplings of NP particles found at LHC Theoretical consensus is that a sample with integrated luminosity ~50-100 ab-1 will reach the required sensitivity Maximum synergy with the findings of LHC will require collection of this sample in the next decade, requiring luminosity ~1036 cm-2s-1 Should LHC fail to find NP (!!) then Super Flavor factories might help to set the factor by which the scale was missed. See talk by Marcello Giorgi – Salle 253, 14:05 today

  5. Asymmetric Super Flavor Factories Belle 2 Japan KEK • KEKB • Incrementally increase Lx40 • Detector based on Belle SuperB Italy LNF Frascati • New machine. • “CRAB waist” achieves high L with low currents. • Asymmetric e+e-L~1036cm-2-s-1 • Detector based on BaBar • Runs from charm threshold (5S) • 80% Longitudinally polarized e- Unique to SuperB

  6. We discuss here prospects for a few selected studies using charm particles from two runs of Super B 75 ab-1 at (4S) BaBar times 150 500 fb-1 at Ã(3770) CLEO-c times 650 BES III times 100 Projections are made from what has already been done in similar studies at BaBar or CLEO-c.

  7. Prospects for Charm at Super B Super Flavour Factories Charm Mixing CP Violation Reach Rare Decays of D Mesons Summary 8

  8. D Mixing - What SuperB Can Do Major Goals: • Improve precision of parameters of two mass eigenstates: xD= (m2-m1)/;yD=(2-1)/(2); |q/p| andM= Arg{q/p} where D 0 = p D1+ q D2and D 0 = p D1- q D2 • Search forCPV • Examine whether CPV originates from the mixing (p = q), from decay (Arg{Af} = Arg{Af})or decay/mixing interference. One Possible Strategy: • Compare (xD, yD) for D0 with (xD, yD) for D0 • Find way to do so for different decays (direct CPV?) • Aim for precision in (xD, yD) of ~10-4

  9. Motivation Of all neutral mesons, the D0 system exhibits the least mixing • Long distance mixing amplitudes predominant but hard to quantify Recent estimates are typically (consistent with current observation) Largely attributed to fact that D0’s are the only neutral mesons that can mix that are made from up-type quarks • Short distance DC=2 SM suppression: D mixing loop involves no t quark • s and d quarks in loops: GIM suppressed • b quark loop suppressed: • So mass difference ampl. xD< O(10-5) Signals for New Physics would be |xD|>>|yD| or any Evidence for CPV

  10. BaBar Mixing Measurements Current measurements exploit interference between direct decays and decays through mixing: Time-dependence (no CPV, to 2nd order in x and y) Interference term is linear in xD, yD BUTrfandfare, generally,unknown Af(D0f) Accessible to D or D K (WS), point on DP, etc D0 “f”: Mix Af(D0f) Strong phase Af = rf eifAf dN/dt ~e- t x [rf2 + rf (y cos f –x sin f)  t + ¼(x2+y2)( t)2] Direct decay Decay through Mixing Interference

  11. Project BaBar to 75 ab-1 @ (4S): Statistical err. only • Uncertainties shrink: • BUT are limited by the DPU • Has biggest effect on xD However, D 0-D 0 differences are mostly independent of systematic uncertainties

  12. Sensitivity to CPV Mixing Parameters qD/pD Several strategies are available: Current World Averages: • D0- D0 parameter asymmetries: • az = (z-z)/(z+z) ~ |qD|2-|pD|2 • where z is • x’,y’ (x,y rotated by K ) • x’’,y’’ (x,y rotated by K), etc. Time-dependent amplitude analysis of Golden channels Semi-leptonic asymmetry aSL = Improve present precision by order of magnitude Also improve distinction between decay modes ~ 5% 1-|qD|4/|pD|4 1-|qD|4/|pD|4

  13. Quantum Correlations from (3770) Data For multi-body channels, we can measure f “bin-by-bin” in their phase-space. m-2 (GeV2/c4) m02 (GeV2/c4) Boost Quantum correlations remove necessity for model describing phase space. X X Can be done for higher multiplicities, too. This provides model-independent measurement of strong phase variation over the Dalitz plot - Also useful for CKM  measurements

  14. Two improvements in mixing precision come from threshold data: Value of Strong Phase Measurements • Dalitz plot model uncertainty shrinks • Information on overall strong phase is added Uncertainty inxDimproves more than that of yD

  15. CPV Reach in Mixing (Strategy I) Search for asymmetries for xD, yD values xD§, yD§ obtained from separate samples of D0 or D0, respectively. To a good approximation: where z can be xD, yD , yCP , y’ , x’’ or y’’ Not all modes allow measurement of xD§, yD§ so asymmetriesaZcan be compared for a variety of channels. Differences would indicateCPVwas in decay rather than in mixing. Systematic uncertainties in z+, z- are likely to be unimportant in these asymmetries, so statistical uncertainties will dominate. az = (z+ – z-) / (z+ + z-) = |q|2 – |p|2

  16. CPV Reach in Mixing (Strategy II) Golden channels provide a direct way to obtain values for |q/p| and Arg{q/p}. We project to 75 ab-1 at Y(4S) the statistical and systematic uncertainties found by Belle in their TDDP analysis of the Ks¼+¼- mode. Uncertainties from the Dalitz plot model will be important, and the CPV reach will be much improved with data from threshold.

  17. CPV Reach in Mixing (Strategy III) Wrong Sign (WS) lepton asymmetry measures CPV in mixing: No CPV See Talk by I. Bigi At Perugia • If measurement lies on curve, CPV is ALL in MIXING aSL |q/p| Current HFAG average !

  18. Time-Integrated CPV

  19. D0’s produced in e+e- collisions at B factories are tagged by the sign of the slow pion from D* decay Two reasons reaching the “per mille” level is a challenge : D0 K+K-, K+K-0, +- ,+-0 Arxiv:0807.0148v1 (2008) NEW Phys.Rev.Lett.100:061803 (2008) Super B should be able to probe interesting levels ~0.1% • Efficiencies fors+ands-are not the same Use DATA to find the asymmetry: • Use (several x106)untagged K -+to map efficiency asymmetry for K –and for+ • Repeat fortagged K -+to mapsasymmetry • D 0 ‘s are produced with asymmetry in * (relative to beam axis) and efficiency depends on * (from Z0/ and higher order effects) • Take average of each cos* range for |cos*| > 0 and < 0 as ACP • Take difference of each cos* range for |cos*| > 0 and < 0 as AFB

  20. This may be where CPV lurks, probably in selected channels. T-odd moments in D0K+K-+- [I. Bigi, arXiv:hep-ph/0107102., Phys. Lett. B 622 (2005) 239] Focus – obtained AT = 1.0 ± 5.7 (stat) ± 3.7 (syst) % BaBar – obtained AT = 1.0 ± 6.7 % (Main syst. Is from PID ~0.35 %) Multi-body decays D0 D0 differences K+K-0 Phys.Rev.D78, 051102 (RC) (2008) +-0 • Dalitz plots for D0 and for D0 are • normalized then compared in unbiassed, • frequentist, model-independent ways: • Bin-for-bin • Legendre moments and correlations • Tests compatible with asymmetry < few% Super B should be able to probe interesting levels <1% SuperB – projected AT = x.x ± 0.05 (stat) ± 0.2 (syst) %

  21. Summary Together with 500 fb-1 from (3770) run, 75 ab-1 at (4S) will result in measurements of xD and yD with precision ~10-4. This will provide a sensitivity to CPV in mixing (q/p) of order a few %. TDDP analysis of golden channels can measure q/p with precision 3-4%. Time-integrated measurements of CPV asymmetries ~0.1%, close to SM limits, will be possible.

  22. Brian Meadows, U. Cincinnati Backup Slides

  23. Estimates for Super B Reach We use only BaBar measurements (ones already in hand) to project to what we can do with 75 ab-1 at (4S); Not all systematic uncertainties scale in the same way that statistical ones do; Examine the possible benefit of using strong phase measurements at DD threshold. Brian Meadows, U. Cincinnati

  24. “Double-Dalitz” Plots: An example from CLEO c e+e- (3770)  (Ks+-) (Ks+-) There are two Dalitz plots correlated in a time-dependent way: If you select CP-odd Ks0 in one, you see “no”Ks0 in the other. If you select RS K*-+ in one, you see only (opp. sign) RS K*+- in the other. EXCEPT: There will be a small signal arising from MIXING. This has a definite time-dependence, making it more identifiable above background. Backgrounds at (3770) are small ! CLEO data: - It works !! J. Napolitano http://indico.ihep.ac.cn/conferenceDisplay.py?confId=176

  25. Project to 75 ab-1 @ (4S): Scale statistical errors as To make projections, choose central values for observables to be consistent with the parameter values from BaBar. Do same for systematic uncertainties They are mostly determined from data. EXCEPT for: • D 0Ks+-analysis has “irreducible” uncertainty inxDand inyDof order1 x 10-3due to uncertainty in Dalitz model.

  26. DD Threshold Measurements Data from DD threshold provide measurement of strong phases such as K and K¼0. They also provide measured values of  in Dalitz plot bins This can be used (with a model for the values forr) to significantly reduce uncertainties in the Dalitz plot model used in the golden channel analyses. As a basis for projection, we take results from CLEO-c: N. Lowrey et al, PRD80, 031105 (2009), 0903.4853 We assume that new data from threshold will reduce the uncertainties in model uncertainty: BES III – ~factor 3 improvement in model uncertainty Super B 500 fb-1DD threshold run – ~factor 10 improvement.

  27. Brian Meadows, U. Cincinnati “Valencia-Warwick” Projection:HFAG (with CPV) Average to SuperB If central values persist: Will observe >> 5 effect !! No-CPV point still allowed at 1σ NOW x x (Alan Schwartz/David Asner – private communication) • Assumptions: • Central values are as reported at ICHEP2008 • Scaling is made only for D0 K-+, D0Ks+- and  measurements. • Systematic errors scale as 1/sqrt(N) • “Further assumes systematic uncertainties are determined by data alone.”

  28. A Few Small Problems We stated that measurements of strong phases using data from DD threshold will add significantly to the precision of our mixing measurements. However, we never did examine this possibility very carefully. It turns out that we ignored an irreducible systematic uncertainty However, this should be reduced with measurements made at charm threshold We did not make any quantitative estimate of our sensitivity to CPV, or a comparison with LHCb’s reach. Brian Meadows, U. Cincinnati

  29. BaBar (IV): Golden Channels D0Ksh+h- (h=¼ or K) Brian Meadows, U. Cincinnati • Final stateis self-conjugate - a mixture of CP-even and CP-odd states.  = 0 • Measures xD and yD directly These are (only slightly correlated ) • xDvs.yD

  30. “HFAG-like” Average of BaBar Data(unofficial) 36 • x vs.y • Good internal consistency • y dominated by yCP • x dominated by • Golden channel decays D0Ks h+h- + Brian Meadows, U. Cincinnati Super B, Elba, Italy, 5/30-6/05/2010

  31. Precision of aSL Uncertainty from a signal S over background B is At (4S), projecting from Babar, we expect single-taggedD*D0+: double-tagged (additional D in event): At (3770), projecting from CLEO-c, we expect D0 K-+ + D0 K-+ : (DCS Bose-forbidden) D0 Xl+ + D0 Xl+: (Needs study) D0 K-+ + D0 Xl+: ( “ “ ) In the last channel, eliminate DCS D0 K-+ using time-dependence (t2e-t/)of WS SL decay interfering with K-+! Not very useful !

  32. Mixing in Charm Sector So far, we know that mixing occurs, BUT Uncertainties are large in the values for the main parameters xD= (m2-m1)/,yD=(1-2)/(1+2), |q/p| and Arg{q/p} where D0 = pD1+qD2 D0 = pD1-qD2 Is xD small as expected in the naïve SM ? We do not know if there is any CPV How self-consistent are all the mixing observables?

  33. Mixing in Charm Sector So far, we know that mixing occurs, BUT We do not know if there is any CPV We are not really sure what are the values for the main parameters xD=(m2-m1)/,yD=(1-2)/(1+2) Is xD small as expected in the naïve SM ? Uncertainties are still very large How self-consistent are all the mixing observables?

  34. Comparison with LHCb (10 fb-1) y y From:P. M. Spradlin (2007), 0711.1661.

  35. CPV From Mixing Measurements

  36. Brian Meadows, U. Cincinnati Correlation with D0 Ks Asymmetry Measurement of S(Ks) and of aSL could eliminate or refine this model: (S) ~ 5 x10-4 (aSL) ~ 0.01 See I. Bigi Friday a.m. If CPV is in MIXING

  37. Brian Meadows, U. Cincinnati Simulation Wish List for TDR Sensitivity tests - Y(4S) simulations Resolution in M(D0),  M and (t) xD, yD, |q/p| using D* D0+  Ks+- yCP and A from D0 K+K- and K-+ (xD2+yD2)/2 from D0 K-e+e T-odd moments analysis Simulations at (3770) Effectiveness of strong phase measurements at (3770) in mixing needs clarification Time resolution acheivable– at least two configurations (DGWG) D0 +- (with background) TDQC simulation study (xD2+yD2)/2 from D0 K-e+e for 2009 document

  38. Brian Meadows, U. Cincinnati Progress Towards a TDR Impressive work has been done both at, and since, the Valencia workshop. http://www.slac.stanford.edu/spires/find/hep/www?irn=8013667 For progress towards a TDR, this is an excellent starting point: Some items not yet covered Measurement of fD , fDs form-factors, … Address experimental issues (tracking, end-cap PID)

  39. Brian Meadows, U. Cincinnati “Super D” / “Super B” Comparison Advantages: D0’s are produced at (3770) at ~3 x the rate of B0’s at Y(4S) D0 decay rates are typically 100xB0 decay rates  So there are many more “double-tags” than in B’s from Y(4S) Example: CLEO have 420 double-tagged Ks+- events from 818 pb-1 that suggests “Super D” will have ~300K If KL+- could be added we would have 1.2M double-tagged events Handicaps wrt TDQC for B’s at Y(4S): D0’s also have little transverse momentum at y(3770) so we rely on the boost bg=p/m [~same as at Y(4S)] for time measurements BUT tD0 < 1/3tB0 sos ~ 30 mm is only about one D0 lifetime We only anticipate running for ~600 fb-1 (comparable to BaBar) Can make TD “Double-Dalitz” Plot fit with many correlations.

  40. Brian Meadows, U. Cincinnati Reminder from KL+- Standard model limit (“unitarity bound”) is Measured value is (6.86 § 0.37) x 10-9 From QED: 1.20 x 10-5 Measured: 5.47 x 10-4 = 6.83 x 10-9 x L.M. Sehgal, PR 183, 1511 (1969) BNL E791, Heinson et al, PRD 51, 985 (1995)

  41. Design Goals for SuperB Suggested by mini-Machine Advisory Committee – Chair, J. Dorfan Unique to SuperB Envisage here a run at (3770) of ~500 fb-1 (650x CLEO-c)

  42. Brian Meadows, U. Cincinnati Bigi, Blanke, Buras, Recksiegel Little Higgs with T-parity. NOT an MFV model arXiv:0904.1545 S. Recksiegel Monika Blanke A. Buras Ikaros Bigi … bets his beard that LHT models would lead to observable CPV in D decays! Later … is willing to grow a beard if CPV is not observed in D decays by 2017!

  43. Brian Meadows, U. Cincinnati For multi-body channels, this means we can measure strong phases “integrated over” the final state. The “coherence” measures the variance in this phase. CLEO measurements (using external mixing information from elsewhere): We need to clarify how we include these measurements in mixing results from the Y(4S) QC in Multi-body Channels

  44. Brian Meadows, U. Cincinnati Ikaros Bigi … is willing to grow a beard if CPV is not observed in D decays by 2017!

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