Leptonic SemiLeptonic Charm Decays Sheldon Stone Syracuse University

Leptonic & Semi-Leptonic Charm Decays Sheldon Stone, Syracuse University CKM 2006 Workshop, Nagoya, Japan, Dec. 12 -16, 2006

What We Hope to Learn n Purely Leptonic Charm Decays D→ + n n n Check QCD calculations including Lattice (LQCD) Look for New Physics Semileptonic decay rates & form-factors Need f. Bs/f. B h from theory. Measure f. D+/f. Ds QCD checks n Use QCD to extract Vcq (See talk of M. Artuso) n Use d. G/dq 2 in conjunction with B decay rates to extract Vub. n Use D l to get form-factor for B l , at same v • v point using HQET (& l ) n Use B l , B K*l+l , along with D l & D K*l at the appropriate q 2 Due to lack of time, many interesting results are omitted n n S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 2

Experimental methods §DD production at threshold: used by Mark III, and more recently by CLEO-c and BES-II. §Unique event properties ØOnly DD not DDx produced World Ave §Large cross sections at y(3770): s(Do. Do) = 3. 72 0. 09 nb s(D+D-) = 2. 82 0. 09 nb Ease of B measurements using "double tags: “ BA = # of A/# of D's §At y(3770) CLEO-c uses beam constrained mass §At 4170 Me. V, invariant mass with energy cut • At Y(4 S) s(charm) ~ 1 nb s(DS) ~ 0. 15 nb S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 3

Leptonic Decays: D(s) + Introduction: Pseudoscalar decay constants _ c and q can annihilate, probability is to wave function overlap or cs Example : (s) In general for all pseudoscalars: Calculate, or measure if VQq is known S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 4

New Physics Possibilities Another Gauge Boson could mediate decay n Ratio of leptonic decays could be modified (e. g. ) n See Hewett [hep-ph/9505246] & Hou, PRD 48, 2342 (1993). S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 5

New Physics Possibilities II Leptonic decay rate is modified by H+ n Can calculate in MSSM. Is mq/mc, so negligible for D+ but not for DS (m. S/mc) n Leptonic decay for DS gets modified by factor of n r n or where R=tanb/m. H See Akeryod [hep-ph/0308260] S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 From Akeroyd 6

Old CLEO Measurements of f. Ds 1. 2. 3. 4. 5. 6. Detected g & m from DS*→ g DS → m+ decay Used missing energy & momentum in half of the event, to estimate 4 -vector. Event half determined using thrust axis Correct 4 -vector to get right DS mass value Measured real m background by doing same analysis on DS*→ g DS → e+ Used D*o → g, Do → K-( +) to measure efficiencies, etc… Used 4. 8 fb-1 at or near Y(4 S) (M. Chadha et al. Phys. Rev. D 58, 32002 (1998)) S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 7

New BABAR Measurements of f. Ds n n n Similar analysis to CLEO [1) detect g & m, 3) correct P 4 , 4) use ge for backgrounds, 5) use D*o → g K( +)], but much improved because they use only events: e+e-→“D” x DS*-, where the “D” is a fully reconstructed Do, D+ or D*+ (B. Aubert et al [hep-ex/0607094]) This gives much better S/B and also missing energy resolution Use 230 fb-1 S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 8

New CLEO-c Measurement of DS+→m+ n n n In this analysis CLEO uses DS*DS events where they detect the g from the DS*→ g DS decay They see all the particles from e+e- → DS*DS, g, DS (tag) + m+ except for the A kinematic fit is used to (a) improve the resolution & (b) remove ambiguities n n n Constraints include: total p & E, tag DS mass, Dm=M(g. DS)-M(DS) [or Dm= M(gm )-M(m )] = 143. 6 Me. V, E of DS (or DS*) fixed Lowest 2 solution in each event is kept No 2 cut is applied S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 9

Invariant masses K - K + p+ Ks hp+ K+ f r+ h p+ hr+ p-p+p+ K*K* from Ks. K-p+p+ Inv Mass (Ge. V) Total # of Tags = 19185± 325 (stat) S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 10

Tag Sample using g n n First define the tag sample by computing the MM*2 off of a g & DS tag All 8 Modes Data Total of 11880± 399± 504 tags, after the selection on MM*2 S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 11

The MM 2 (From Simulation) n To find the signal events, compute Signal m S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 Signal t , t→ 12

MM 2 Results from 200 pb-1 n n Clear DS+→m+ signal for case (i) Events <0. 2 Ge. V 2 are mostly DS→t+ , t → + in cases (i) & (ii) No DS→e+ seen, case (iii) 6 DS→t+ , t → + in case (i) m+ peak 64 events DATA 200/pb <0. 3 Ge. V in CC accepts 99% of m+, 60% + & K+ Case (i) 24 events accepts 1% of m+, 40% + & K+ Case (ii) DATA 200/pb >0. 3 Ge. V in CC 12 events Electron Sample S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 13

Sum of DS+→m+ + t+ , t → + n n n n Two sources of background A) Backgrounds under invariant mass peaks – Use sidebands to estimate In m+ signal region 2 background (64 signal) Sideband bkgrnd 5. 5± 1. 9 B) Backgrounds from real DS decays, e. g. + o o, or DS→ t+ , t → + o. . < 0. 2 Ge. V 2, none in m signal region. Total of 1. 3 additional events. B(DS → + o) < 1. 1 x 10 -3 & g energy cut yields <0. 1 evts Total background < 0. 2 Ge. V 2 is 6. 8 events, out of the 100 Sum of case (i) & case (ii) m +t signal line shape S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 K 0 p+ 100 events 14

Branching Ratio & Decay Constant n DS+→m+ n n n 64 signal events, 2 background, use SM to calculate t yield near 0 MM 2 based on known t /m ratio B(DS+→m+ ) = (0. 657± 0. 090± 0. 028)% DS+→t+ , t+ → + n n Sum case (i) 0. 2 > MM 2 > 0. 05 Ge. V 2 & case (ii) MM 2 < 0. 2 Ge. V 2. Total of 36 signal and 4. 8 bkgrnd B(DS+→t+ ) = (7. 1± 1. 4± 0. 3)% By summing both cases above, find Beff(DS+→m+ ) = (0. 664± 0. 076± 0. 028)% § f. Ds=282 ± 16 ± 7 Me. V n B(DS+→e+ )< 3. 1 x 10 -4 n S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 15

Measuring DS+→t+ , t+→e+ n n § B(DS+→t+ ) B(t+→e+ )~1. 3% is “large” compared with expected B(DS+→Xe+ )~8% Technique is to find events with an e+ opposite DS- tags & no other tracks, with calorimeter energy < 400 Me. V No need to find g from DS* 400 Me. V Xe+ B(DS+→t+ ) =(6. 29± 0. 78± 0. 52)% f. Ds=278 ± 17 ± 12 Me. V S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 16

& n Weighted Average: f. Ds=280. 1± 11. 6± 6. 0 Me. V, the systematic error is mostly uncorrelated between the D+→m+ measurements (More data is on the way) n Previously CLEO-c measured M. Artuso et al. , Phys. Rev. Lett. 95 (2005) 251801 n Thus f. Ds/f. D+=1. 26± 0. 11± 0. 03 S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 m+ K 0 + 17

Comparisons with Theory n n We are consistent with most models, more precision needed Using Lattice ratio find |Vcd/Vcs|= 0. 22± 0. 03 1993 S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 18

Comparison with Previous Experiments 280. 1± 11. 6± 6. 0 ? -2 3. 6± 0. 9 n 248 ± 15 ± 6 ± 31 Difficult to average without a clear measurement of B(DS→f +). In any case CLEO-c result dominates S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 19

Limits on New Physics n Lepton Universality n n n G(DS+→t+ )/G(DS+→m+ ) = 9. 9± 1. 7± 0. 7 SM = 9. 72 G(D+→t+ )/G(D+→m+ ) < 4. 77 (90% cl) SM = 2. 65 Limits on charged Higgs n According to Akeryod Unquenched Lattice: f. Ds=249± 3± 16 Me. V Our result: 280. 1± 11. 6± 6. 0 Me. V Take ms/mc=0. 076 (PDG) n Then the ratio of our result/SM gives >1, NP <1 n n n S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 20

Limits on Charged Higgs Mass n n n Can set limits in the tanb m. H± plane Competitive with CDF But depends on Lattice Model. Don’t take seriously yet Summary of the 95% CL exclusions obtained by LEP & CDF. The full lines indicate the SM expectation (no H± signal) and the horizontal hatching represents the ± 1 s bands about the SM expectation. S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 21

Exclusive Semileptonic Decays u Best way to determine VQi. Qf magnitudes of CKM elements, in principle is to use semileptonic decays. Decay rate |VQi. Qf|2 u Kinematics: u Matrix element in terms of form-factors (for D Pseudoscalar l+ u For l = e, f-(q 2) 0: S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 22

Form-Factor Parameterizations n In general n Modified Pole n Series Expansion Hill & Becher, Phys. Lett. B 633, 61 (2006) S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 23

CLEO-c Exclusive Decays (281 pb-1) n Both Tagged results 699 28 6796 84 295 20 2910 55 & untagged using reconstruction Samples overlap, so choose only one result U = Emiss– |Pmiss| (Ge. V) n reconstruction has larger statistics but larger systematic errors S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 1347 49 14397 132 450 29 5846 88 Beam Constrained mass using Emiss & Pmiss to find 24

Exclusive Branching Ratio Summary D o → K- e+ ν D o → π- e+ ν (2006) n (2006) preliminary Theory needs to catch up S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 25

CLEO-c Form-Factors Compared to Lattice predictions* D Ke f+(0)=0. 73± 0. 07 a=0. 50± 0. 04± 0. 07 D e f+(0)=0. 64± 0. 03± 0. 06 a=0. 44± 0. 07 *C. Aubin et al. , PRL 94 011601 Assume Vcs = 0. 9745 LQCD DATA FIT (tagged) . Belle CLEO-c Assume Vcd = 0. 2238 CLEO-c (2005) LQCD Belle . S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 DATA FIT (tagged) 26

Other Form-Factor Measurements BELLE: PRL 97, 061804 (2006) [hep-ex/0604049] & FOCUS Unquenched LQCD Quenched LQCD Simple pole model Do Kℓ Belle Kℓ ~2. 5 k signal events LQCD: Aubin et al. , PRL 94, 011601 (2005) n (hep-ex/0607077) CLEO-c & Belle somewhat disagree with LQCD, Belle 2 28/18 (K) & 9. 8/5 ( ) Belle ℓ 232 signal events q 2 (Ge. V 2) S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 27

Pseudoscalar Form Factors D→K e+ S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 D→ e+ 28

D Form Factors (CLEO-c) n Can be used to detemine Vub along with B , D K* & B K* + - (See Grinstein & Pirjol [hep-ph/0404250]) Rv = 1. 40 0. 25 0. 03, R 2 = 0. 57 0. 18 0. 06 D+ o - cos q 2 B(D 0 -e+ )= (1. 56 0. 16 0. 09) 10 -3 B(D+ 0 e+ )= (2. 32 0. 20 0. 12) 10 -3 Do + - cos e Line is projection for fitted RV, R 2 S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 U = Emiss– |Pmiss| (Ge. V)29

CLEO-c Discovery of Do→K e+ n B(Do→K 1(1270)e+ )*B(K 1(1270) →K- + -) = consistent with ISGW 2 prediction S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 30

Conclusions not preliminary n n f. Ds=280. 1± 11. 6± 6. 0 Me. V preliminary n f. Ds/f. D+=1. 26± 0. 11± 0. 03 preliminary No violation of Lepton Universality observed Accurate semi-leptonic form-factors confronting LQCD & perhaps indicating deviations Much more to do n n n S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 31

The End CKM 2006 Workshop, Nagoya, Japan, Dec. 12 -16, 2006

Untagged: Form-Factor Results Simp. Pole Mod. Pole S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 33

D p/Ken: Which Form Factor Parameterization? CLEO preliminary All these models describe the data pretty well (except when forcing pole mass to nominal value in pole model). S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 34

Compare with Limits from Belle t Belle: assumes f. B and |Vub | are known, take the ratio to the SM BF. r. B=1. 13 0. 51 But taking no theoretical error is abhorrent S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 Excluded by CLEO-c 95% CL 35

Goals in Leptonic Decays n f. B & f. Bs/f. B needed to improve constraints from Dmd & Dm. S/Dmd. Hard to measure directly (i. e. B h t+ measures Vubf. B ), but we can determine f. D+ & f. Ds using D + and use them to test theoretical models (i. e. Lattice QCD) S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 Constraints from Vub, Dmd, Dms & B t+ 36

New CLEO-c Measurements of f. Ds n n n Two separate techniques (1) Measure DS+→m+ along with DS→t+ , t → +. This requires finding a DS- tag, a g from either Ds*-→g Ds- or Ds*+→g m+. Then finding the muon or pion using kinematical constraints (2) Find DS+→t+ , t →e+ opposite a Ds- tag S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 37

Comparisons with Theory CLEO-c n 280. 1± 11. 6± 6. 0 222. 6± 16. 7 +2. 8 -3. 4 1. 26± 0. 11± 0. 03 We are consistent with most models, more precision needed S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 38

CLEO-c Untagged D K(or ) e S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 39

Define Three Classes n n n Class (i), single track deposits < 300 Me. V in calorimeter (consistent with m) & no other g > 300 Me. V. (accepts 99% of muons and 60% of kaons & pions) Class (ii), single track deposits > 300 Me. V in calorimeter & no other g > 300 Me. V (accepts 1% of muons and 40% of kaons & pions) Class (iii) single track consistent with electron & no other g > 300 Me. V S. Stone (Syracuse) CKM 2006 Workshop, Dec. 12 -16, 2006 40