HERA. Halle NORD (H1) Hall NORTH (H1) Hall nord (H1) Halle OST (HERMES) Hall EAST (HERMES) Hall est (HERMES)

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1 Karshon Uri Institute of Science Weizmann PENTAQUARK5 U.S.A. JLab, Search for the c (31) Pentaquark Pentaquark Searches in Israel on behalf of the Collaboration - October, 5 U T L I N E Introduction + (153) Signal The of baryons decaying to strange particles Production for the Ξß Pentaquark Search Summary

2 - HERA and at DESY Introduction E R A Z E U S H GeV 8 9 GeV p 7:6 ß GeV s ) vertex finding, momentum Tracking particle ID measurement, Halle NORD (H1) Hall NORTH (H1) Hall nord (H1) HERA Halle OST (HERMES) Hall EAST (HERMES) Hall est (HERMES) Halle WEST (HERA-B) Hall WEST (HERA-B) Hall ouest (HERA-B) HASYLAB DORIS Elektronen / Positronen Electrons / Positrons Electrons / Positons Protonen Protons Protons Synchrotronstrahlung Synchrotron Radiation Rayonnement Synchrotron DESY PETRA Halle SÜD () Hall SOUTH () Hall sud () e ) ( p Calorimetry ) energy measurement xperiments: H1,, HERMES

3 kinematic regimes: Two Inelastic Scattering (DIS) Q > 1GeV Deep Variables Kinematic transfer) : Q = q = (k k ) (Four-momentum Bjorken-x scaling variable: x = e visible in main detector Scattered (PHP) Q < 1GeV ; < Q >ß Photoproduction Integrated Luminosity (pb ) 1 Physics Luminosity e Introduction - HERA I: Luminosity, Kinematic variables e e Days of running Q P q of energy transfer: y = P q P k Fraction p CMS energy) : W flp = (P + q) ο = 4 Ee E p y (fl No scattered e in main detector ) quasi-real photon

4 The + (153)! K S p(μp) signal HERA-I DIS data (11 pb 1 ) Phys. Lett. B 591 (4) 7 US 867; K S candidates with ß 6% background ß identified by ionization energy loss de/dx otons the M (K S p) distribution with Q > GeV to two Gaussians it background function ) χ =ndf = 35=44 threshold Gaussian consistent with a PDG ± bump at 148 MeV irst KS p(p) Q > GeV ( + ) = 151:5 ± 1:5(stat:) +:8 1:7(syst:) MeV M width=6:1 ± 1:6(stat:) MeV Gaussian ± :5 MeV Resolution=: Fit Gaussian Background ARIADNE MC (BW) = 8 ± 4(stat:) MeV ) ± 48 events ß 4:6 s.d χ / ndf =35 / 44 peak= ± 1.5 MeV width= 6.1 ± 1.6 MeV events=1 ± M (GeV) S S K K p p Gaussian fit Single worse χ =ndf, peak robust! seen in both charges (inset) Signal S μp fit: 96 ± 34 (.8 s.d.) K If real - evidence for antipentaquark

5 + cross section at measured kinematic region: etermine > GeV, :4 < y < :95, p T ( + ) > :5 GeV, j ( + )j < 1:5 Q measured in the same kinematic region Λ from Λ selected by de=dx with same cuts as for + rotons MC RAPGAP/ARIADNE A( + ) used ± ± with For Q > GeV : For +! K p)=ff(λ) = ff( + cross section (prel.)! e + X! e ± K px) = 15 ± 7(stat:) (syst:)pb (ep to well-known baryon Λ: ompare + ) and ff( + )=ff(λ) as a function of Q min ff( 3 5 (prel.) 96- p) / σ(λ) (prel.) 96- A( + ),A(Λ) Acceptance using calculated.4< y <.95 P T >.5 GeV η <1.5 K + σ(θ.1.1.4< y <.95 P T >.5 GeV η < M = 15 MeV and 1.6 1% decay to K Sp(μp).4 A( + ) ß 4% ; A(Λ) ß 1% Q min (GeV ) Q min (GeV ) ± :9 +1: :9 )% (4:

6 events enriched by K S and p(μp) PHP light-q fragmentation from + not seen in PHP (and low Q ) due to low S=B (large combinatorial perhaps Production of baryons decaying to strange particles (prel.) is the only high-energy experiment that sees the + (153) US a statistical fluctuation or a peculiar production mechanism? it (prel.) 96- photoproduction S/B = peak= 85.5 ±.6 MeV width= 5.5 ± 1.6 MeV events=553 ± 19 (K Sp(μp)) for 3 data samples: M Q > 1 GeV ; Q > GeV PHP; + peak at high Q See c signal for all 3 samples Λ mpare + production to known baryons with similar decay channels increase of S=B for Λ c vs. Q Strong =.3 (PHP) S=B 5 5 Fit Background Q >1 GeV S/B = peak= 87.9 ± 1.9 MeV width= 5.3 ± 3. MeV events=78 ± 67 (DIS low Q ).13 (DIS high Q ) Q > GeV S/B = peak= 9. ±.5 MeV width= 6.8 ± 3. MeV events=11 ± M(K s p(p)) background and particle multiplicity)

7 statistics ) mass and width fixed from overall Q > 1 GeV fit ow number of Λ c for all 4 spectra: N (Λ c ) = 131 ± 4; > mparable c produced in parton fragmentation region Λ expected for c fragmentation via BGF fl Λ g! cμc as ± 36; p 16 ± 38; μp 116 Λc production properties > 1 GeV peak studied in forward vs. rear pesudorapidity region Q for p's and μp's separately 145 ± 34; < a) Q > 1 GeV χ / ndf =7 / 4 peak= 87.9 MeV (fixed) width= 5.3 MeV (fixed) events=131 ± 4 Lab K (p+p), η > S (prel.) 96- Fit Background b) Lab K (p+p), η < S Combinations/.1 GeV a) Q > 1 GeV χ / ndf =7 / 4 peak= 87.9 MeV (fixed) width= 5.3 MeV (fixed) events=16 ± 36 KS b) p (prel.) 96- Fit Background KS p 5 χ / ndf = / 4 peak= 87.9 MeV (fixed) width= 5.3 MeV (fixed) events=145 ± M (GeV) χ / ndf =3 / 4 peak= 87.9 MeV (fixed) width= 5.3 MeV (fixed) events=116 ± M (GeV)

8 Production properties of baryons decaying into K p(k + μp) light-quark fragmentation origin, Indicates partons from hard interaction as for Λ c not (prel.) 96- photoproduction peak= ±.4 MeV width= 7.7 ±.4 MeV events=1356 ± 561 S/B = (K p(k + μp)) for 3 data samples: M Q > 1 GeV ; Q > GeV PHP; significant numbers of Reconstruct for all 3 samples Λ(15) N (Λ(15)) = 1356 ± PHP ± 199 Q > 1 GeV ± 83 Q > GeV Fit Background Q >1 GeV peak= ±.5 MeV width= 6.6 ±.6 MeV events=658 ± 199 S/B =.7 Λ c, S=B similar for PHP and DIS Unlike =.5 (PHP) S=B (DIS low Q ).7 (DIS high Q ) peak= ± 1.8 MeV width= 6. ± 1.8 MeV 5 events=313 ± 83 Q > GeV S/B = M(K p) if Λ(15) production rate Possible to < n ch > proportional

9 Q > 1 GeV peak studied in > and < regions 15) for p's and μp's separately ± 143; p 17 ± 14; μp 14 Λ(15) production properties number for all 4 spectra: N (Λ(15)) = 1337 ± 151; > mparable ± 17; < 146 a) Q > 1 GeV χ / ndf =39 / 3 peak= ±.8 MeV width= 6. ±.8 MeV events=1337 ± Lab K p + K p, η > (prel.) 96- Fit Background Combinations/.5 GeV a) Q > 1 GeV Dominant production mechanism of Λ(15) is pure fragmentation χ / ndf =4 / 3 peak= ±.7 MeV width= 6. ±.7 MeV events=14 ± 14 + K p (prel.) 96- Fit Background b) + - Lab K p + K p, η < χ / ndf =8 / 3 peak= ±.7 MeV width= 6. ±.7 MeV events=146 ± M (GeV) b) χ / ndf =6 / 3 peak= ±.8 MeV width= 6.5 ± 1. MeV events=17 ± K p M (GeV)

10 No statistically significant ++ Search in the K + p(k μp) mass spectra (prel.) M (K + p(k μp)) for 3 data samples: PHP; Q > 1 GeV ; Q > GeV photoproduction Some peak at ß 1:54 GeV for Q > 1 GeV state found Q >1 GeV at RHIC see ++ candidate STAR M ß 1:53 GeV in d-au and Au-Au at Q > GeV M(K p)

11 due to known baryons Ξ(13), ±(1385) Peaks clearly seen are Search in the Λß ± mass spectra (prel.) 96- photoproduction (153)! K Sp peak is a new ± state, If decay + (153)! Λß + is also allowed the M (Λß ± ) 3 data samples: for Q > 1 GeV ; Q > GeV PHP; Fit Background Q >1 GeV χ / ndf =37 / 3 peak= ± 1.3 MeV width= 4. ± 1. MeV events=57 ± statistically significant peak No 153 GeV near Q > GeV ± 8 7 M(Λ π ) Q > 1 GeV, a peak with 4:4ff is seen For 16 MeV consistent with the not-well near established PDG states ±(158) or ±(16)

12 events are more favorable High-Q is produced mainly in the forward region ( > ) (153) + rate is larger than + (153) production properties of + (153) in e + e collisions may indicate that the n-observation related to proton fragmentation. In this case: S.Chekanov, hep-ph/598 is S K (p + p), η Lab > Q > GeV χ / ndf =59 / 46 peak= ± 1.8 MeV width= 7.7 ± 1.5 MeV events=195 ± 4 (prel.) 96- Fit Background a) + (153) produced by pure If as Λ(15) fragmentation signal should be seen for ) > and < both 153) Q > GeV peak studied in > and < regions 4 KS (p + p), η Lab < Q > GeV two Gaussian fit yields: A ( (153)) = 195 ± 4; > N ± 3; < χ / ndf =65 / 5 peak= MeV (fixed) width= 6.1 MeV (fixed) events= ± 3 b) M (GeV) (153) production related to ) remnant? proton

13 Number of K Sp events larger than for K S μp conclusion possible due to complicated background strong S μp near 148 MeV region K + (153) production properties Q > GeV peak studied separately for p's and μp's 153) Q > GeV KS p a) (prel.) 96- Fit Background χ / ndf =49 / 44 peak= 15. ± 3.3 MeV width= 6.3 ± 3.1 MeV events=96 ± 34 Combinations /.5 GeV Q > GeV KS p b) χ / ndf =35 / 44 peak= ± 3. MeV width= 1.4 ±.6 MeV events=16 ± 49 M (GeV) M (GeV) ( (153)) = 16 ± 49; p N ± 34; μp 96 A two Gaussian fit yields:

14 lit the (153) signal to K Sp and K S plots: Two Gaussian fit; one free parameter for the overall normalization ft parameters fixed from sum of the two distributions her for number of events in peaks; one for background normalization o and widths fixed to the sum of the two distributions aks + (153) production properties μp combinations for > : inconsistent with sum of the two distributions not plots: Two Gaussian fit with 3 free parameters: ght has better χ /ndf and yields 5:4ff statistical significance for the p channel S K p, η Lab > Q > GeV χ / ndf =6 / 53 (prel.) 96- Scaled fit for KS (p+p) η> Background a) Combinations/.5 GeV S K p, η Lab > Q > GeV (prel.) 96- Fit Background χ / ndf =54 / 51 peak= MeV (fixed) width= 7.7 MeV (fixed) events=15 ± 3 a) 1 KS p, η Lab > 1 KS p, η Lab > 1 Q > GeV 1 Q > GeV χ / ndf =61 / 53 b) M (GeV) 4 χ / ndf =53 / 51 peak= MeV (fixed) width= 7.7 MeV (fixed) events=64 ± b) M (GeV)

15 identified by ionization energy loss de/dx otons Λ,Ξ signals: higher statistics; smaller background US for the Ξß pentaquark Search Found narrow peaks in all Ξß combinations (M ß 186 MeV, width < 18 MeV) 49: HERA-I DIS data (11 pb 1 ) Phys. Lett. B 61 (5) 1 US Λ! pß ; μ Λ! μpß + ; Ξ! Λß ; μ Ξ +! μ Λß + from secondary vertices construct for Q > 1 GeV for each decay channel separately (Ξß) 96- NA49 signal Ξ - π - Ξ - π + + Ξ π - + Ξ π (a) (b) (c) (d) M(Ξπ)(GeV) a clean signal of See (153)! Ξ ß + (+c.c.) Ξ No evidence for a signal at 186 MeV (fixed target) has good acceptance NA49 forward region in Non-observation in at central ) region - fragmentation contradiction if NA49 signal no in forward direction mainly

16 (Ξß) for Q > 1 and Q > GeV a Ξ (153)! Ξ ß + (+c.c.) signal See (153) fitted to Gaussian Ξ ± 3:7(stat.)MeV width=9:5 :5ff Significance fit yields: M = 1533:3 ± 1: (stat.) MeV ; width = 6:6 ± 1:4 (stat.) MeV 153) ± 3 events 19 signal much bigger than NA49 53) for the NA signal evidence Search for the Ξß pentaquark (all Ξß charge combinations).6.4 Ξ (153) χ /ndf=84/88 candidates=19±3 peak=1533.3±1. MeV σ=6.6±1.4 MeV 96- (a) Fit Background Fit Q >1 GeV 95% C.L. upper limit on R Combinations / 1 MeV Q > GeV (b) + threshold background function plot: Peak at ß 169 MeV (?) Right be due to PDG Ξ(169) *** Can. 1 yields: Fit = 1687:5 ± 4: (stat.) MeV M NA49 signal M(Ξπ)(GeV) NA49 signal M(Ξπ)(GeV) curve is 95% C.L. upper limit ratio R = Ξ 3= (Ξ 3= )=Ξ (153) rly function of M (Ξß) in the range MeV (R ß :1 :5)

17 for the c (31) Pentaquark Search a narrow D Λ p resonance at ß 3:1 GeV Phys. Lett. B 588 (4) 17 saw Low-P p : Prob(χ ) p > :15; P < 1:35 GeV; de=dx > 1:3 (Clean p's from de=dx) ) High-P p : Prob(χ ) p > :15; P > GeV (Nicer H1 signal without de=dx cut) ) (a) 95- background wrong charge D* ± (Kπ)π s N(D* ± ) = 468 ± (b) D* ± (Kπππ)π s N(D* ± ) = 199 ± 5 HERA-I data (16.5 pb 1 ) Eur. Phys. J. C38 (4) 9 Λ± US D ß ± s M = M (D Λ± ) M (D ) ο m ß! P T (D Λ ± ) > 1:35 GeV, j (D Λ ± )j < 1:6 D Λ signals in D decay modes Clean! K ß + ; D! K ß + ß + ß (+ c.c.) D 4 c searched for with D Λ 's from bands N (D Λ ± ) ß 6; 6 yellow 5 (c) Q > 1 GeV N(D* ± ) = 868 ± 13 5 (d) Q > 1 GeV N(D* ± ) = 483 ± 1 the DIS sub-sample Q > 1 GeV For (D Λ ± ) ß 13; 5 (x 4 of H1 sample) N 5 15 calibrated tagged p(μp) from Λ's de/dx (ln(de=dx) ln(de=dx) with expected ) = χ ff ln(de=dx) candidates with P T > :15 GeV selected by p(μp) ) p > :15; A(Prob(χ ) p > :15) = 85: ± :1% Prob(χ M(Kππ s ) - M(Kπ) (GeV) M(Kππππ s ) - M(Kπππ) (GeV) Two strategies for p-selection:

18 High-P p M (D Λ p) spectra for the D! K ß + channel (D Λ p) = M (Kßß s p) M (Kßß s ) + M (D Λ+ ) PDG M (D Λ p) resolution at ß 3:1 GeV is ß 4 MeV M full sample DIS sample (a) D* ± (Kπ)π s like-sign combinations (b) P(p) < 1.35 GeV, de/dx(p) > 1.3 mips Combinations per 1 MeV (a) 1995-, Q > 1 GeV D* ± (Kπ)π s like-sign combinations 15 (b) P(p) < 1.35 GeV, de/dx(p) > 1.3 mips 1 All protons 5 Low-P p (c) P(p) > GeV 3 (c) P(p) > GeV M(D p) = ΔM ext + M(D + ) PDG (GeV) M(D p) = ΔM ext + M(D + ) PDG (GeV) are M (D Λ± p ± ) like-sign combinations stograms evidence for a signal at 3:1 GeV (also in the D! K ß + ß + ß mode) No! K ß + analysis repeated with very similar cuts to H1 ) no signal

19 upper limits for c production (D Λ p) = M (Kßß s p) M (Kßß s ) + M (D Λ+ ) PDG M D Λ p window GeV. in visible rate of R = 1% is A by 9 s.d. (5 s.d) excluded the full (DIS) sample. for < :3% (< :35%) for R (DIS) sample. full limits: < :37%(< :51%) for full (DIS) sample. cepted-corrected c ) B c! D Λ p < :16% (< :19%) for the full (DIS) combined sample!! K ß + D! K ß + ß + ß D l sample Combinations per 1 MeV (a) D* ± (Kπ)π s backgr. fit fit interpol. (b) 95- D* ± (Kπππ)π s MC signal on top of interpolation histograms are Yellow c signals normalized MC c=d Λ = 1% after H1 to top of a background on fit (solid curves) 8 (c) Q > 1 GeV (d) Q > 1 GeV C.L. upper limits on 95% c! D Λ p=d Λ ) calculated R( 6 D* ± (Kπ)π s D* ± (Kπππ)π s S sample M(D p) = ΔM ext + M(D + ) PDG (GeV)

20 N ( +! K Sp) > N (! K S μp) p-remnant effect (?) ) cannot be reference" state for + production Λ(15) Summary ing all HERA-I high-energy data (ß 1 pb 1 ) in the detector: In inclusive ep DIS, a narrow peak is seen in M (K Sp) (M (K S μp)) For Q > GeV : fitted signal has 1 ± 48 events (4.6 s.d.) = 151:5 ± 1:5(stat:) +:8 1:7(syst:) MeV; (BW) = 8 ± 4(stat:) MeV M Q > GeV : ff( +! K p) = 15 ± 7(stat:) +36 8(syst:) pb For +! K p)=ff(λ) = (4: ± :9 +1: :9 )% ff( Unlike Λ c and Λ(15): + produced mainly in the forward (proton) region may explain non-observation in other experiments?

21 95% C.L. R(( c! D Λ p)=d Λ ) < :3%; At DIS (Q > 1 GeV ) R < :35% for acceptance correction: R cor < :37%; After cor (H1) = (1:59 ± :33 +:33 :45 )% R from HERA-II are crucial to clarify Results pentaquarks status at HERA the Summary No evidence for the NA49 Ξß signal at 186 MeV in inclusive ep DIS (153)) < :9 (95% C:L:) (Different kinematic region?) R(Ξ(186)=Ξ resonance structure seen in M (D Λ± p ) around 3:1 GeV from 6,6 D Λ No ) limits are not compatible with the H1 c signal

22 > 1 GeV Q S! ß+ ß selection K p T (K ) > :3 GeV, j (K )j < 1:5 Backup: + Event selection All HERA-I data (11 pb 1 ) e + p, e p collisions at CM energy GeV CTD tracks p T > :15 GeV, j j < 1:75 S reconstructed from K tracks secondary-vertex photon conversions Remove (e + e ) < 5 MeV M Combinations /. GeV x Fit Q > 1GeV and Λ's M (ßp) < 1:11 GeV M(π + π - ) (GeV) :483 < M (ß + ß ) < :513 GeV ß 867; K S candidates with ß 6% background

23 4 ( < # positive charge (a) 5 4 de / dx (mips) de / dx (mips) 7 & negative charge (b) p (GeV) 8 < < ( - $ : % # p (GeV)

24 Backup: K S p(μp) results I earch for + in M (K S p) for Q > 1; 1; 3; 5 GeV structures near See GeV and below 1:5 are ARIADNE MC simulation Histograms to data above 1:65 GeV normalised W < 15; > 15 GeV Combinations/.5 GeV Q >1 GeV ARIADNE MC Q >3 GeV (a) (c) Q >1 GeV (b) Q >5 GeV (d) 8 at 1:5 GeV Signal with Q increases decreases with W 15 1 Q >1 GeV W<15 GeV Q >1 GeV W>15 GeV (± bumps not included in the MC) 5 (e) (f) M (GeV)

25 Backup: K S p(μp) results II the M (K S p) distribution with Q > GeV to single Gaussian it background function P 1 (M m) P (1 + P 3 (M m)) threshold ( + ) = 15: ± 1:5 MeV M ß 3:9 s.d. Significance m = m K + m p ; P 1;;3 = free parameters χ =ndf = 51=47 35 Q > GeV KS p (p) 96- Fit Signal Background ARIADNE MC χ / ndf =51 / 47 peak= 15. ± 1.5 MeV width= 4.9 ± 1.3 MeV events=155 ± 4 consistent with Width (ß MeV) resolution M (GeV)

26 Backup: results K S p(μp) earch for (153) in M (K Sp) for Q > ; 3; 4; 5 GeV Combinations/.5 GeV Q > GeV χ (prel.) 96- Fit Background / ndf =48 / 45 peak=15 ± 1 MeV events=184 ± 39 (a) Q >3 GeV χ / ndf =59 / 45 peak=15 ± 1 MeV events=139 ± 33 (b) Q >4 GeV χ / ndf =6 / 45 peak=15 ± 1 MeV events=118 ± 9 (c) Q >5 GeV χ / ndf =55 / 45 peak=153 ± 1 MeV events=15 ± 6 (d) M (GeV)

27 Backup: Fit results for Q > GeV Gaussian+Bkg. Gaussians + Bkg. Fit =ndf M» 17 MeV 51/47 35/44 χ (MeV) :1 ± :9 mass 1 width (MeV) - 15:5 ± 3:4 Peak ± 11 events (MeV) 15: ± 1:5 151:5 ± 1:5 mass width (MeV) 4:9 ± 1:3 6:1 ± 1:6 Peak 155 ± 4 1 ± 48 events

28 Backup: trigger selection irst level trigger: regional energy sums CAL-FLT: tracks" looking to the nominal interaction point CTD-FLT: : scattered electron (and CTD-FLT) DIS PhP : CTD-CAL and CTD-FLT Untagged Tagged PhP : 44m and 35m taggers, CTD-CAL and CTD-FLT econd level trigger: : scattered electron and CAL energies DIS PhP : CAL energies and SLT tracks (high-w) Untagged Tagged PhP : 44/35m taggers, CAL energies and SLT tracks hird level trigger: DIS : almost offline selection Inclusive Λ ± in DIS : reconstructed D Λ ± in DIS events (low Q ) D PhP : dijet events Inclusive Λ ± in PhP : reconstructed D Λ ± in tagged/untagged PhP events D

29 Backup: Main systematic studies for c selecting of DIS with Q > 15 GeV cos Λ (p) > :7, where Λ (p) is the angle require p direction in 5q r.f. and 5q direction in the lab between reflections from D 1 ;DΛ! DΛ± ß studying/removing all cuts as close as possible to H1 selection making No signal ) varying de=dx requirements for low-p selection no de=dx requirements for high-p selection out 1ffi ; using z(d Λ± ) > : instead removing the cut on P T (D Λ± )=E T

30 M ext = M (Kßß S ß 4 ) M (Kßß s ) dn cos ff / cos ff (1 + ;L+ s = 3=) d dn cos ff / 1 cos ff ( + ;L+ s = 3=) d narrow bump? Additional = 11 ± 49 N (a) Preliminary 11 pb -1 1 (4); DΛ (46)! DΛ ± ß D Backup: Orbitally excited P-wave D mesons Backgr. wrong charge M(Kππ s π 4 ) - M(Kππ s ) + M(D * ) (GeV) fit with fixed M,, -dimensional and helicity distribution: resolution 5 (b) (c) M(Kππ s π 4 ) - M(Kππ s ) + M(D * ) (GeV) angle ff : between ß 4 and ß s helicity D Λ ± rest frame in (D 1 ) = 56 ± 65 N (D Λ ) = 3 ± 6 N = 398:1 ± :1(stat:) +1:6 :8(syst:) MeV M New D meson? Interference?

31 Fit to a form : 1 + R cos ff : consistent with R =, i.e. J P = 1 + Charm-strange ± (536) meson Backup: D s1 DΛ ± Ks, K s! ß + ß 1! (536) s1 ± M ext = M (Kßß S ß 3 ß 4 ) M (Kßß s ) M (ß 3 ß 4 ) Combinations / 3.5 MeV 1 8 (prel.) (17 pb -1 ) K s candidates in events with a D ± candidate (D s1 ) = 6:3 ± 9:3 6 s1 ) = 534: ± :6 ± :5 MeV (ο M PDG ) (D 4 (prel.) (17 pb -1 ) Fit : Gauss + A (ΔM ext ) B s1 D ± N(D ± K s ) = 6 ± 9 : between K ff angle Helicity M(π 3 π 4 ) (GeV) S and ß s in D Λ± r.f. = :53 ± :3(stat:) +:5 :14(syst:) ( prel.) R (D + s1! D Λ K + ) : R = :3 +:4 :3 CLEO M(D ± K s ) = ΔM ext + M(D + ) PDG + M(K ) PDG (GeV) not contradict R = 1 does for J P = 1 ; + expected

32 K S K S Backup: Resonances in DIS 6 5 f (17)/a (13) f (155) f (171) 96- cosθ KK <.9 cosθ KK.9 3 B-W + Background Breit-Wigner Background Several resonances observed 4 3 in gluon-rich Produced environment 1 f (171) = glueball candidate?? M(K s K s ) (GeV)

33 Predictions: (hep-ph/37341); Wu-Ma (hep-ph/444): Jaffe-Wilczek c ß 7 MeV ) too light to decay to D mesons ) decay weakly to + ß can M ( c ) > M (DΛ± ) + M (p) = 948 MeV, If c can decay to D Λ± p Backup: Charm Pentaquarks + = uuddμs exists, heavy pentaquarks, such as Since uuddμc should also exist = (hep-ph/37343): Karliner-Lipkin ( c ) = 985 ± 5 MeV ; ( c ) ο 1 MeV M Cheung (hep-ph/38176): M ( c ) = MeV [ud][ud] c =Θ c [ud][ds] c [ud][ds] c + [ud][us] c [ud][us] c + decays dominantly to D p + or D n (+ c.c.) [ds][us] c [ds][ds] c [ds][us] c + [us][us] c is sensitive to resonances decaying to D Λ ± (D 1, D Λ, D s1 ) US very narrow resonances ( +, f (155), f (171)) ) Search for c signal in M (D Λ p) (+ c.c.) spectra

34 DIS sample of ß 34 D Λ± H1 sees a narrow resonance in a Λ p) and M (D Λ+ μp) with M = 399 ± 3(stat:) ± 5(syst:) MeV D ple with ß same ratio to D Λ 4 3 H1 D* p + D* + p Signal + bg. fit Bg. only fit Backup: H1 observation Entries per 1 MeV γ p H1 D* p + D* + p wrong charge D M(D*p) [ GeV ] M (D*p) [ GeV ] et al., Phys. Lett. B 588, 17 (4) Atkas measured Gaussian width 1 ± 3(stat:) MeV e with experimental resolution compatible signal consists of 5:6 ± 11: events e 1% of the total D Λ production rate" ughly (with large background) also seen in a photoproduction nal

35 careful de/dx calibration More + analysis w.r.t. tuned using Parameters p(μp) from Λ decays tagged Prob(χ ) p > :15 A(Prob(χ ) p > :15) = 85: ± :1% Backup: de=dx for the c analysis ß's from K S decays tagged select p(μp) candidates: To (ln(de=dx) ln(de=dx) expected ) = χ ff ln(de=dx) ln(de=dx) = a= p n ff hits used for de/dx measurement n=no.of

36 Combinations per 1 MeV (a) M (D Λ p) for Kßßß Backup: 1995-, D* ± (Kπππ)π s like-sign combinations (b) Q > 1 GeV M(D p) = ΔM ext + M(D + ) PDG (GeV) evidence for a signal at 3:1 GeV in the D! K ß + ß + ß mode

37 M (D Λ p) with H1-like cuts Backup: K ß + analysis repeated with cuts very similar to H1! Combinations per 1 MeV (a) (b) 1995-, D* ± (Kπ)π s Q > 1 GeV, H1 selection criteria wrong charge (Kπ)π s D* ± MC Q < 1 GeV, H1 selection criteria M(D p) = ΔM ext + M(D + ) PDG (GeV) evidence for a signal at 3:1 GeV

38 Λ decay (Kß)ß s (Kßßß)ß s Both D channels channel backgr 1678 ± ± 19 N Λ ) 468 ± ± 5 N(D c! DΛ p=d Λ ) < :9% < :33% < :3% R( cor ( c! DΛ p=d Λ ) < :47% < :5% < :37% R window 5 N backgr 5:8 ± 9: 19:8 ± 8:8 N Λ ) 868 ± ± 1 N(D c! DΛ p=d Λ ) < :41% < :69% < :35% R( cor ( c! DΛ p=d Λ ) < :59% < 1:6% < :51% R! c ) B c!d Λ p < :% < :56% < :19% f(c Backup - data sample Full window N! c ) B c!d Λ p < :18% < :33% < :16% f(c with Q > 1 GeV DIS