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Introduction: Pentaquarks

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Institut f r Kern- und Teilchenphysik, Technische Universit t Dresden, D-01062 Dresden, Germany ... Institut f r Kern- und Hadronenphysik, FZ Rossendorf, ... – PowerPoint PPT presentation

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Title: Introduction: Pentaquarks


1
Kai-Thomas Brinkmann CAP 2005 June 6, 2005
Search for the Pentaquark(s)
www.frauenkirche-dresden .org
  • Introduction Pentaquarks
  • Experimental Evidence
  • Experiments Searching for the T
  • Other Pentaquark States
  • Summary and Outlook

2
Introduction Pentaquarks
  • Quark model hadrons qq and qqq
  • Other states not ruled out!
  • Soliton model calculation antidecuplet set of
    5q states qqqqq
  • New family of (exotic) baryons!

3
Introduction Pentaquarks
T S 1 mass 1530 MeV/c2 small width G lt
15 MeV M.V. Polyakov et al., EPJA 9 (00)
115 G 2-4 MeV D. Diakonov, V.Petrov,
hep-ph/0505201 T ? K0p and Kn
MNK GeV/c2
Evidence from a number of experiments using
different combinations of targets and probes
4
Experimental Evidence
5
Experimental Evidence
Saphir
CLAS
Saphir, PLB572,127(03)
?p ? K0 ?? ? K0(n)K? M (15404 2) MeV G lt 25
MeV 4.8 s not seen in pK?
?d ? pK- ?? ? pK- (n)K? M (15425) MeV G lt 21
MeV 5.3 s
CLAS, PRL91,252001(03)
6
Experimental Evidence
T(1530)
?(1520)
ZEUS, hep-ex/0404007 (YITP workshop, Kyoto,
Japan, Feb. 2004)
7
Experimental Evidence
Gaussian statistical significance estimated
background fluctuation
8
Experimental Evidence
A number of experiments do not see a signal
  • BaBaR, Delphi, BES, CDF, HyperCP, E690, HERA-B,
    Aleph, Phenix
  • very high statistics and excellent resolution
  • high energy
  • inclusive
  • ee- or hadronic probes

9
Experimental Evidence
BaBar upper limits on T and ?5 production (2
MeV mass resolution)
10
Experimental Evidence
BaBar upper limits on T and ?5-- production
hep-ex/0502004
11
Experimental Evidence
A number of experiments do not see a signal
  • BaBaR, Delphi, BES, CDF, HyperCP, E690, HERA-B,
    Aleph, Phenix
  • very high statistics and excellent resolution
  • high energy
  • inclusive
  • ee- or hadronic probes

and, just recently, CLAS in ?p?K0K(n)
12
?p?KK0(n)
Comparison between Saphir and new CLAS results,
see R. deVitas talk at the APS spring meeting,
TAMPA, 2005
13
Indirect Evidence KN scattering
Haidenbauer, Krein (PRC68, 052201 (2003))
Workman, Arndt et al. (PRC70, 028201(04))
Scattering (and charge exchange) data suggest G lt
1 MeV
14
Experiments Searching for the T
pp ? ST, T ? K0p / Kn
Production in pp with high cross
sections Strangeness tagging
15
  • 184 m circumference
  • 1011 protons per filling
  • _at_ 620 MeV (25 mA, T 600 ns)
  • PcMAX 3,65 GeV
  • ?p/p ? 10-4, ? ? mm mrad
  • (1 mm Ø 0,18) beam cooling
  • up to 80 polarization
  • Extracted beam
  • 105...109 protons /s in spill
  • 1 s...gt2 min spill, 5 s inter-spill
  • OR 2109 p in 200 ns
  • Quasi-DC, polarized

16
M. Fritsch, Ch. Hess, H.Koch, W. Meyer, E. Radke,
G. Reicherz, A.Wilms Institut für
Experimentalphysik, Ruhr-Universität Bochum,
D-44780 Bochum, Germany H. Dutz, A. Raccanelli,
A. Wagner Phys. Institut der Universität Bonn,
D-53115 Bonn K.-Th.Brinkmann, S.Dshemuchadse,
H.Freiesleben, R.Jäkel, L.Karsch, E.Kuhlmann,
M.Schulte-Wissermann, G.Y.Sun, W.
Ullrich Institut für Kern- und Teilchenphysik,
Technische Universität Dresden, D-01062 Dresden,
Germany W.Eyrich, J.Georgi, A. Lehmann, H.Mörtel,
L.Pinna, C.Pizzolotto, W.Schroeder, F.Stinzing,
A.Teufel, M.Wagner, St.Wirth Physikalisches
Institut, Universität Erlangen-Nürnberg, D-91058
Erlangen, Germany M.Abdel-Bary, S.Abdel-Samad,
M.Drochner, A.Gillitzer, K.Kilian, S.Marwinski,
H.P.Morsch, N.Paul, J. Ritman, E.Roderburg, S.
Schadmand, T.Sefzick, A.Ucar, P.Wintz,
P.Wüstner Institut für Kernphysik, FZ Jülich,
D-52425 Jülich, Germany and Zentral Labor für
Elektronik , FZ Jülich, D-52425 Jülich,
Germany A.Filippi, S.Marcello Dipartimento di
Fisica Sperimentale, University of Torino,
I-10125 Torino, Italy and INFN, Sezione di
Torino, I-10125 Torino, Italy H.Clement, E.
Doroshkevich, K. Ehrhardt, A. Erhardt, P.
Gonser, G.J.Wagner Physikalisches Institut,
Universität Tübingen, D-72076 Tübingen,
Germany P.Michel, K.Möller, L. Naumann Institut
für Kern- und Hadronenphysik, FZ Rossendorf,
D-01314 Dresden, Germany P. Zupranski, Soltan
Institut for Nuclear Studies, PL-00681
Warsaw supported by BMBF Verbundforschung FZ
Jülich (FFE), EU-LIFE Program
17
The COSY-TOF experiment high-acceptance
Time-of-Flight spectrometer with vertex tracking
18
The COSY-TOF experiment
COSY-TOF designed to identify strangeness
(pp ? pK?, pK0S, pKS0, nKS)
  • Reaction identification
  • primary track ? proton
  • delayed decay V of KS ? ?? without start
    scintillators / Si
  • decay of ?, kink
  • time-of-flight of proton

pp ? pKSS Search for the T
19
EXPERIMENT MODEL
pp ? pK? Resonances in strangeness production
PDG 2003
20
pp ? pKSS Reaction identification
using geometry
  • Ks decay V mass of pp-
  • missing mass of track w/ kink (S) from event
    topology

21
pp ? pK0S Search for the ??
COSY-TOF collaboration PLB595 (04) 27
Sum of two experiments (in 00 and 02) yields
about 1000 events of pp ? pKSS
  • Excursion in K0p spectrum at
  • mass (1530 5) MeV/c²
  • width lt 18 MeV/c² (FWHM)
  • compatible with detector resolution
  • statistical significance of 4-6 s
  • cross section (0.40.1stat0.1sys) µb

K0p
22
pp ? pK0S Search for the ??
COSY-TOF collaboration PLB595 (04) 27
Sp
acceptance correction using phase space
K0p
K0p
K0p
K0S
23
pp ? pK0S Search for the ??
? COSY-TOF beam time October / November 2004
  • improved experimental setup
  • 109 raw events taken to tape
  • expect about factor 5 in pKs statistics over
    published result (gt 5000 pKs events, 300 in peak
    if signal persists)
  • analysis ongoing and improved with respect to
  • blind analysis ½ of the data to optimize
    analysis, rest for result
  • independent analysis at several institutes in
    parallel with different codes, emphasis on
    different detector aspects
  • systematics of Monte-Carlo treatment
  • use of redundant information (ToF of proton and
    pions, energy losses, ...)
  • common calibration database

24
pp ? pK0S Search for the ??
? COSY-TOF beam time October / November 2004
  • data on disk
  • calibration method ready
  • one-time cal. parameters done
  • geometry implemented
  • Monte Carlo all approaches compatible
  • reconstruction software modifications in
    progress
  • runwise calibration in progress
  • data reconstruction next step

4 hours of running
25
Experiments on the properties of the ??
  • Measureable quantum numbers
  • isospin ? look at other channels, e.g. Kp
  • parity ? pp with double polarization

Hanhart et al., hep-ph0410293 PLB590(04)39
PLB606(05)67
K only
K only
K and K
pp?ST
P
(-)LSI -1
P
measure excitation function for ?? (3P0,1) 3sS
½s0(2AxxAyy) (and ?? (1S0) for
reference)
26
Experiments Searching for the T
www.frauenkirche-dresden .org
  • All running experiments in the field have started
    programs to prove the existence of the exotics.
  • CLAS p and d target
  • SPring8 higher statistics
  • First results with high statistics from CLAS do
    not support the SAPHIR evidence on the proton.

27
Other Pentaquark States
NA49
C. Alt et al., PRL92, 042003 (04)
28
Other Pentaquark States
No signal seen in pK ? Isoscalar state
hep-ex/0411027, Pentaquark 2004 proceedings
29
Other Pentaquark States
A. Aktas et al., PLB588,17 (04)
30
Summary and Outlook
www.frauenkirche-dresden .org
  • Several experiments have seen evidence for a
    manifestly exotic (S 1) T(1530) in the 5s
    range.
  • If it exists, it likely is an isoscalar, spin ½
    (?) baryon of unknown parity.
  • Experimental programs focussing on this object
    are under way.
  • Hadroproduction will add usefull complementary
    information.
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