Wolfgang Menges, Queen Mary Experimental Prospects for CP and T Violation Studies in Charm Giampiero Mancinelli University of Cincinnati CHARM 2007 – Cornell, USA.
Download ReportTranscript Wolfgang Menges, Queen Mary Experimental Prospects for CP and T Violation Studies in Charm Giampiero Mancinelli University of Cincinnati CHARM 2007 – Cornell, USA.
Wolfgang Menges, Queen Mary Experimental Prospects for CP and T Violation Studies in Charm Giampiero Mancinelli University of Cincinnati CHARM 2007 – Cornell, USA Outline THE RESEARCH CP Violation in the Charm Sector THE PLAYERS CLEO-c BESIII Direct CP Violation Experimental Techniques Giampiero Mancinelli, University of Cincinnati – CHARM 2007 CP/T Violation Searches 2/25 Charged D decays Neutral D decays CP states 3-Body CP Violation at the (3770) T-odd Correlations E-791 Summary: Current Status Future Prospects Conclusions SUPER-KEK Charming CP Violation Sakharov conditions for baryogenesis (1967): Baryon number violation CP violation Non-equilibrium SM CP Violation in kaon and beauty systems too small Need other sources Three types of CP Violation CPV in mixing matrix (tiny) Giampiero Mancinelli, University of Cincinnati – CHARM 2007 2 3/25 Rm2 p 2M 12 i12 1 q 2M 12 i12 CPV in decay amplitudes AD f A D f See previous session for CPV in mixing CPV in interference between mixing and direct decay, for a subset of final states (mixing suppressed, hence very small) Af q Af i f Rm e p Af Af Direct CP Violation in Decay ACP 2 Im A1 A2* sin( 1 2 ) ( f ) ( f ) 3 10 ( f ) ( f ) A1 2 A2 2 2 Re A1 A2*cos( 1 2 ) 2 weak amplitudes strong phase difference with phase difference Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Two amplitudes with different strong & weak phases needed to observe CPV (in SM from tree and penguins) 4/25 THE DECAYS e.g. SCS D0 → K+KW+ D0 Cabibbo Favored (CF) c s u s Singly Cabibbo Suppressed (SCS) Doubly Cabibbo Suppressed (DCS) c dsu K+ K- u c sdu c ssu c ddu u D0 c W+ s u Only SCS decays probe penguins u s K+ s u K- CP Violation in the Standard Model Standard Model charm physics is “CP conserving” 2x2 Cabibbo quark mixing matrix is real (no CPV at tree level) CPV in penguins and loops (by virtual b quarks) Diluted weak phases in SCS decays In mixing, CPV enters at O(VcbVub/VcsVus) In decay, penguin CPV enters at O(VcbVub/VcsVusas/p) No weak phases in CF and DCS decays …except D+ g K0p+ - SM ~0.003 (CPV in K0 decay) Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Note: in general we can separate direct and indirect CP Violation by: 5/25 Combine measured ACP with time-dependent CPV measurements (both for CP eigenstates) Just using time-integrated measurements (assuming negligible new CPV in CF or DCS decays): The time-integrated CP asymmetry for CF decay to a CP eigenstate gives indirect ACP e.g: ACP_DIRECT(P+P−) = ACP(P+P−) − ACP(KS0p0) , P = K, p Light readings: New physics and CP violation in singly Cabibbo suppressed D decays. Y. Grossman, A. L. Kagan, Y. Nir, Phys.Rev.D75:036008,2007. “I Know She Invented Fire, But What Has She Done Recently?" - On The Future Of Charm Physics, I.I. Bigi, Int.J.Mod.Phys.A21:5404-5415,2006. Mixing and CP-violation in charm. A. A. Petrov, Nucl.Phys.Proc.Suppl.142:333-339,2005. A Cicerone for the Physics of Charm, S. Bianco, F. L. Fabbri, D. Benson, I. Bigi, Riv. Nuovo Cim. 26N7 (2003) 1. CP Violation and New Physics (NP) Extensions of the Standard Model (ex: SUSY) contain CP violating couplings that should show up at some level (1%?) in flavor physics Precision measurements and theory are required to detect the NP BSM Physics: charm is unique probe of the up type quark sector, especially models in which CKM mixing is generated in the up sector top quarks: do not hadronize No T0-T0 oscillations Hadronization helps observability of CP Violation up quarks : p0, η and η′ do not decay weakly Giampiero Mancinelli, University of Cincinnati – CHARM 2007 No p0-p0 oscillations possible CP asymmetries mostly excluded by CPT theorem) 6/25 (relatively) Large statistics Flavor models where the CKM mixing is “generated” in the up sector predict large D − D mixing and sizable CPV in D, but smaller effects in the B sector SCS D decays are now more sensitive to gluonic penguin amplitudes than are charmless B decays CF and DCS decays: Direct CPV in charm would mean NP SCS decays: SM ~ 10-3 from CKM matrix Experimental Approaches for DCPV Measure asymmetry in time integrated partial widths Measure asymmetries in final state distributions on Dalitz plots Exploit quantum coherence of DD produced in (3770) decays Study T-violation in 4-body decays of D mesons (assuming CPT) with triple product correlations (T-odd) Giampiero Mancinelli, University of Cincinnati – CHARM 2007 All analyses (except CLEO-c) share many common features 7/25 Many D0s produced in colliders, Easy to determine the flavor of the D0 (by unbiased tag: D* g D0p) Common backgrounds (e.g. Kp) Random p combining with a real D0gK+pMultibody D0 decay from D*gD0p Random Kpp combinatoral background Signal and Background yields taken from mKpvs DM(D*-D0) Signal shape/resolution functions/efficiency calibrations taken from CF modes p(D*) cut to suppress from BgD*gD decays Often normalize asymmetries to CF (or other) modes Keep many systematics to a minimum D+ → K−K+p+, p-p+p+ D+ → K−K+p+ D+ → p-p+p+ 193 pb-1 CDFII ~55000 events 80pb-1 ~42500 events 80fb-1 K−K+p+ K+K-p- BABAR m(p-p+p+) 8/25 p+ p- K*0K+ K*0K- m2(p-p+) Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Phys. Rev. D71, 091101 (2005) Large statistics gives access to detailed features in Dalitz plots K−K+p+ K+K-p- m2(p-p+) http://www-cdf.fnal.gov/physics/new/bottom/040422.dplus/ D0 g KK, pp - I SM CPV~10-3 in single Cabibbo suppressed modes (KK,pp), but null in Cabibbo allowed (Kp) BR(D0->KK) >> BR(D0->pp) (R~2.8) – Large FSI and/or penguin contributions NP CP asymmetries Standard Model (Buccella et al, 1995) g KK: (0.01 ± 0.08)%, pp: (0.002 ± 0.001)% CDF II Use D0Kp as normalization mode D0Kp Yield: 180K D0KK Yield: 16220 200 Giampiero Mancinelli, University of Cincinnati – CHARM 2007 123 pb-1 9/25 Phys. Rev. Lett. 94, 122001 (2005) Issues: Tracking charge asymmetry partially reconstructed D background for KK mode D0pp Yield: 7334 97 D0 g KK, pp - II BABAR Analysis Difficulties: Precise quantification of asymmetry in D0 flavor tagging Forward-backward asymmetries in cc production (novel issue) Interference in e−e+ -> cc as mediated by either a virtual photon or a virtual Z0. Higher-order QED box- and Bremsstrahlung-diagram interference effects Can produce asymmetries due to boost of the CMS relative to the lab at asymmetric BABAR Data corrected for charge-dependent detection efficiencies Giampiero Mancinelli, University of Cincinnati – CHARM 2007 By tagging with an independent sample of D0 decays 10/25 Systematics: All corrections used for data will be calculated from data. Goal: reduce systematics in these measurements to the 0.1% level Soft-Pion Tagging efficiency corrections calculated from the CF decay (Kp) With 400 fb-1 we expect: KK g s(ACP)= ~ 0.3 10-2 (stat.) pp g s(ACP )= ~ 0.5 10-2 (stat.) Both results expected to be statistically dominated CLEO-c’s New! At the (3770) Measurements 281 pb-1 Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Pure DD final state, no additional particles Low particle multiplicity (DD) = 6.4 nb (U(4S)gBB ~ 1 nb) Single tag sample Mostly CF modes High efficiencies 11/25 Uncertainties ~1% most cases Charged Kaon tracking largest syst. ~0.7% SCS Why Dalitz Plot Analyses? In case of indirect CPV and final CP eigenstates the time integrated and time dependent CP asymmetries are: Universal Equal to each other In contrast, for direct CPV: The time-integrated asymmetries are not expected to be universal Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Parts of phase-space might have different asymmetries 12/25 They may even cancel each other out when integrated over the whole phase-space New Physics might not show up in the decay rates asymmetries It could show up simply in the phase difference between amplitudes! 3-Body Dalitz Plot Analyses - I 3-Body decays permit the measurement of phase differences The Dalitz plot technique allows: Increased sensitivity to CP asymmetry Probes the decay amplitude rather than the decay rate. Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Access to both CP eigenstates (e.g. D0p0, f0p0, 0p0, …) and non eigenstates (e.g. D0+-p-+, K*+-K-+, …) with relatively high statistics in the modes D0pp+p0, D0K-K+p0, … 13/25 As measurements are normalized to the whole phase space, the flavor dependence of ps tagging efficiency is null and the effect of mistagging is very small. CLEO D0p-p+p0 - Difference in the integrated coherent sum of all amplitudes across the Dalitz Plot between D0 and D0 events D0gKSp-p+ - Full Dalitz analysis (see next slide) 3-Body Dalitz Plot Analyses - II BABAR (expect results this Fall) D0p-p+p0 D0p-p+p0, D0K-K+p0 14/25 MODEL INDEPENDENT approach: use moments of the cosine of the helicity angle for each of the three channels ( h-h+, h-p0, h+ p0); plot vs invariant mass. Measure asymmetry in these moments. The phase/interference information is (mostly) contained in the odd moments Decay rate asymmetry is contained in the even moments. D0→ρ0π0 b=0 =0 MC Follows CLEO’s KSpp analysis technique, (Phys.Rev.D70:091101,2004). m2(p-p+) m2(p-p+) Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Parameterize the amplitude coefficients explicitly in the form: A eiδ = a ei(α + β) (1 + b/a) (for D0) A' eiδ' = a ei(α - β) (1 - b/a) (for D0) Calculate |b| / |a|, values, asymmetries in the fit fractions for each isobar. m2(p-p+) MODEL DEPENDENT approach: fit D0 and D0 Dalitz plots separately, with a resonance (isobar) model (higher systematic uncertainties) D0→ρ0π0 b=-0.05 = -5o MC m2(p-p+) (3770): Quantum Correlation Analysis - I At the (3770) (CLEO-c) e+e- (3770) D0D0 22% double tagging efficiency (~0.1% @ U(4S)) Same number of DD fully reconstructed as BB @ U(4S) Pure JPC = 1-- initial state g CP+ Unique CPV search strategy Complementary to other experiments K+ Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Quantum Correlation Analysis (TQCA): Due to quantum correlation between D0 and D0, not all final states allowed. 15/25 K If a D0 (tag) decays to a CP eigenstate f1, CP conservation requires the recoiling state f2 to have a definite CP as well, which must be of opposite sign: - (since l = 1) e.g. K+K- DCP ’’(3770) DCP Ksp0 (-1) + - - e e+ CP(f1 f2) = CP(f1) CP(f2) (-1)l = CP+ - D0 l = CP+ D0 p p+ (3770): Quantum Correlation Analysis - II New! Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Reconstruct both D mesons (double tag) 16/25 Forbidden by CP Conservation CP+ CP+ CP- CP- CP+ CP- Kp Kp Kp Kp Kp CP± CP± Kp Interference of Cabibbo Favored with Doubly Cabibbo Suppressed X Kln Unaffected Improved technique + KL CP+ modes 281 pb-1 Maximal constructive interference Forbidden (Bose Symm., if no D mixing Interference: Two paths to K-p+ vs K+p- <Kp|D0>/<Kp|D0> = rei Data favors QC interpretation: constructive and destructive interference and no D mixing Data consistent with no C+ initial state, (s~1.5%, stat dominated) “hence” no CPV CP+ vs CP+ CP- vs CPCP+ vs CPK-p+ vs K-p+ K-p+ vs K+pKp vs CP+ Kp vs CP- cos = 1.06 0.19 0.06 T Violation: T-odd Correlations Method searches for Triple Product Asymmetries in (e.g.) D0 → K−K+p−p+ T-odd correlations can be formed using the momenta of the decay products (and assuming validity of the CPT theorem): Giampiero Mancinelli, University of Cincinnati – CHARM 2007 C T pK pp pp 17/25 Under time reversal T, CT →−CT . CT<>0 does not necessarily established T-Violation, because FSI can “fake” this asymmetry(*) Consider D0 → K+K-p+pwhere we can compute: C T pK pp pp Finding: C T CT establishes T violation. We can build T-odd asymmetries as: AT CT 0 CT 0 CT 0 CT 0 CT 0 CT 0 CT 0 CT 0 And the T-Violation asymmetry as: AT Viol AT 1 A AT 2 T tests T-Violation even with strong phases Some references: E. Golowich and G. Valencia, Phys. Rev. D 40, 112 (1989) I.I. Bigi, Proceedings of KAON2001, 417 (2001) (*) I.I. Bigi, A.I. Sanda,‘CP Violation’, Cambridge University Press 2000 T-Violation Measurements Giampiero Mancinelli, University of Cincinnati – CHARM 2007 D0 → K−K+p−p+ 18/25 Yield: 828 FOCUS 370 fb-1 Yield: ~32000 BABAR Preliminary D0 → KS0K+p−p+ FOCUS Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Direct CP/T Violation Results – D0 Decays 19/25 Experiment (year) Decay mode ACP (%) CDF (2005) D0 K+ K- 2.0 1.2 0.6 CLEO (2002) D0 K+ K- 0.0 2.2 0.8 FOCUS (2000) D0 K+ K- - 0.1 2.2 1.5 CDF (2005) D0 p+ p- 1.0 1.3 0.6 CLEO (2002) D0 p+ p- 1.9 3.2 0.8 FOCUS (2000) D0 p+ p- 4.8 3.9 2.5 CLEO (2001) D0 K0S K0S - 23 19 CLEO (2001) D0 p0 p0 0.1 4.8 CLEO (2001) D0 K0S p0 0.1 1.3 CLEO (1995) D0 K0S 2.8 9.4 CLEO (2005) D0 p+ p- p0 CLEO (2004) D0 K0S p+ p- BELLE (2005) 1 (+9-7) 5 Comments Partial list Dalitz plot – integr. - 0.9 2.1 (+1.6-5.7) Dalitz plot analysis D0 K+ p+ p- p- - 1.8 4.4 A of ratios DCS/CF FOCUS (2005) D0 K+ K- p+ p- - 8.2 5.6 4.7 CLEO (2007) D0 K- p+ - 0.4 0.5 0.9 CLEO (2007) D0 K- p+ p0 0.2 0.4 0.8 CLEO (2007) D0 K- p+ p+ p+ 0.7 0.5 0.9 BELLE (2005) D0 K+ p- p0 BABAR (2007) New! - 0.6 5.3 A of ratios DCS/CF D0 K+ p- - 2.1 5.2 1.5 A of ratios DCS/CF BELLE (2007) D0 K+ p- 2.3 4.7 A of ratios DCS/CF FOCUS (2005) D0 K+ K- p+ p- 1.0 5.7 3.7 T violation - TPCor Ne w! Direct CP/T Violation Results – D+ Decays Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Experiment (year) Decay mode 20/25 ACP (%) Comments BABAR (2005) D+ K- K+ p+ 1.4 1.0 0.8 A of ratios SCS/CF BABAR (2005) “ D+ p+ 0.2 1.5 0.6 BABAR (2005) “ D+ K*0 K+ 0.9 1.7 0.7 Resonant substructure of D+ K- K+ p+ CLEO (2007) D+ K- K+ p+ - 0.1 1.5 0.8 FOCUS (2000) D+ K- K+ p+ 0.6 1.1 0.5 A of ratios SCS/CF E791 (1997) D+ K- K+ p+ - 1.4 2.9 A of ratios SCS/CF E791 (1997) “ D+ p+ - 2.8 3.6 E791 (1997) “ D+ K*0 K+ - 1.0 5.0 Resonant substructure of D+ K- K+ p+ FOCUS (2002) D+ K0S p+ - 1.6 1.5 0.9 CLEO (2007) D+ K0S p+ - 0.6 1.0 0.3 CLEO (2007) D+ K0S p+ p0 0.3 0.9 0.3 CLEO (2007) D+ K0S p+ p+ p- 0.1 1.1 0.6 CLEO (2007) D+ K- p+ p+ CLEO (2007) D+ K- p+ p+ p0 CLEO (2007) DS+ K+ h - 20 18 CLEO (2007) DS+ K+ h’ - 17 37 CLEO (2007) DS+ K0S p 27 11 CLEO (2007) DS+ K+ p0 2 29 E791 (1997) D+ p+ p- p+ FOCUS (2005) D+ K0S K+ p+ p- 2.3 6.2 2.2 FOCUS (2005) DS+ K0S K+ p+ p- - 3.6 6.7 2.3 - 0.5 0.4 0.9 1.0 0.9 0.9 - 1.7 4.2 New ! Ne w! A of ratios SCS/CF T violation through triple product correlations Partial list Average Result, by Mode Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Decay mode 21/25 ACP (%) D0 K+ K + 1.4 ± 1.2 D0 KS0 KS0 2.3 ± 1.9 D0 p+ p HFAG + my averages Decay mode ACP (%) D+ K- p+ p+ - 0.5 1.0 D+ K- p+ p+ p0 + 1.0 1.3 + 1.3 ± 1.3 D+ KS0 K+ + 7.1 ± 6.2 D0 p0 p0 + 0.1 ± 4.8 D+ K+ K p+ + 0.6 ± 0.8 D0 p+ p p0 + 1 ± 9 D+ p+ p p+ 1.7 ± 4.2 D0 KS0 p0 + 0.1 ± 1.3 D+ KS0 K+ p+ p 4.2 ± 6.8 D0 K p+ - 0.4 ± 1.0 D0 K p+ p0 + 0.2 ± 0.9 D0 K p+ p+ p- + 0.7 ± 1.0 D0 K+ p 0.8 ± 3.1 D0 K+ p p0 0.1 ± 5.2 D0 KS0 p+ p 0.9 ± 4.2 D0 K+ p p+ p 1.8 ± 4.4 D0 K+ K p+ p 8.2 ± 7.3 D+ KS0 p+ 0.9 ± 0.9 D+ KS0 p+ p0 + 0.3 ± 0.9 D+ KS0 p+ p+ p- + 0.1 1.3 For most references See the HFAG pages Partial list SCS modes AT http://hal9000.mib.infn.it/~pedrini/hfag/charm_asymcp.html http://hal9000.mib.infn.it/~pedrini/hfag/charm_todd_asym.html Future Prospects – Current Efforts - I D0gKK, pp CDF yield prospects 2M D* tagged D0Kp per 1 fb-1 sACP) ~ 10-3 is achievable with full Tevatron run (4-9 fb-1) - at SM limit Issue will be if trigger can cope with Luminosity increase BABAR: 1 ab-1 KK s(A)~0.2% (stat) pp s(A)~0.3% (stat) Giampiero Mancinelli, University of Cincinnati – CHARM 2007 D+ g K+K-p 22/25 BABAR – now s(A)~0.45 (systematically dominated – (syst~0.8)) 1 ab-1 s(A)~0.28% (stat) Dalitz Analysis: fit fractions and phase differences ~ 1% and 1o precisions D0gp+p-p0 Dalitz Analysis BABAR 200,000 signal events @ 1 ab-1 in 1s mass region. s(A) (stat) ~ 0.25 % (integrated) If the asymmetry is larger, but confined to only a part of the phase-space or only to certain specific decay(s), or both (constructively) in amplitude phases and magnitudes, our observation potential might be higher (or lower if destructively) Future Prospects – Current Efforts - II T-Odd Correlations BABAR (KKpp) now ~ 0.9-0.6% level (if systematics under control) 1 ab-1 0.55-0.35% Relevant datasets I am aware of (larger backgrounds than KKpp): Giampiero Mancinelli, University of Cincinnati – CHARM 2007 CLEO: D0gp+p-p+p- 7,300 - D0gp+p-p0p0 2,700 – D+gp+p-p+p0 5,700 BABAR: D0gp+p-p+p- - current ~140,000 – 1 ab-1 ~320,000 + many large CF decays datasets from all 3 experiments 23/25 NOTE: Expect similar yields/results from BELLE Future Prospects – Future Efforts BESIII – SUPER-D-too Factory (KEK and/or Frascati) – LHCb BEPCII/BESIII Data taking beginning of 2008 - 3 yrs @ 3770 = 30M DD/yr = 90M DD = ~20 times full CLEO-c dataset Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Super-B (D, t…) 24/25 10 ab-1/yr at U(4S) With option to lower energy to ~4 GeV (~1ab-1/yr) LHCb Will implement a dedicated D* trigger stream selecting huge and clean samples of hadronic D modes In one year of running at nominal lumi (2·1032 cm-2s-1): Expect 250 - 500 M D* D0p decays with D0Kp channel = 100 times CDF ! K-K + A < 0.08 (CLEO-c), < 0.004 (BESIII) s(A) ~1 x 10-4 (stat.) LHCb/yr s(A) ~6 x 10-5 (stat.) Super-B/yr (3770) Quantum Correlation Analysis A < 0.025 (CLEO-c) s(A) ~0.01 (just KK, pp) (BESIII) s(A) ~7x 10-4 (stat.) Super-B/yr KSp-p+ Dalitz analysis Super-B (5 years = 50 ab-1) A < 5 10-4 Conclusions Charm physics provides unique opportunities for indirect search of NP Theoretical calculation of x, y have large uncertainties Physics BSM hard to rule out from D0 mixing measurements alone Observation of (large) CPV g robust NP signal SCS D decays now more sensitive to gluonic penguin amplitudes than charmless B decays Giampiero Mancinelli, University of Cincinnati – CHARM 2007 Exciting new results (CLEO, Belle, BABAR): 25/25 Total errors ~1% level BUT far from observation Now entering the interesting domain Promising future: Current experiment ~0.1-0.3% in the “best” modes Future efforts (Super-Bs, LHCb, BESIII) ~ 0.001-0.01%