Exotic narrow resonance searches in the systems K s0p, K s0 and p in pAinteractions at 10 GeVc Petro

1
Exotic narrow resonance searches in the systems
K s0p, K s0? and ? p in pA-interactions at 10
GeV/c Petros Aslanyan 1,2, (1) Joint
Institute for Nuclear Research.(2) Yerevan
State University . paslanian_at_jinr.ru.
The XVIIth International Conference on Elastic
and Diffractive Scattering the Château Royal de
Blois, France, from Sunday, May 15-20, 2005.

• 1. Introduction.
• 2. Method.
• 3.Invariant mass spectrum analysis
• 3.1. (K s0p)- system
• 3.2. ( K s0? ) -system
• 3.3 ( ?p ) - system .
• Conclusion.

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What are penta-quarks?
Minimum quark content is 5 quarks. Exotic
penta-quarks are those where the antiquark has a
different flavor than the other 4 quarks Quantum
numbers cannot be defined by 3 quarks alone.
Example uudds
Baryon number 1/3 1/3 1/3 1/3 1/3 1
Strangeness 0 0 0 0 1 1
e.g. uuddc, uussd
c.f. L(1405) uudsu or uds
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Multi-quark states, glueballs and hybrids have
been searched for experimentally for a very long
time, but none is established.
1 D. Diakonov, V. Petrov, and M. Polyakov, Z.
Phys. A 359 (1997) 305. 2 V.Guzey and
M.Polyakov, arXiv hep-ph/0501010,2005.
Meson( q q ) Baryon(q q q)

• Exotic S 1
• Results from a wide range of recent experiments
  are consistent with the existence of an exotic
  S1 resonance, the ?(1540) with a narrow width
  and a mass near 1540 MeV 1.
• Narrow width lt 15 MeV
• Results from this experiment
• M ? (1540?8) MeV/c2,
• ? ? (9.2 ?1.8) MeV/c2.
• PDG-04
• ? ? (9.2 ?0.3) MeV/c2.

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Evidence for Penta-Quark States
This is a lot of evidence. However,
Nomad
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?--(1862)
NA49
pp collision at Ecm17.2GeV

• Also evidence for ?0(1862)
• ( I 3/2 )

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• Exotic S 0
• Low mass 1710 MeV
• Narrow width lt 40 MeV
• Jp1/2

Studies which have claimed to see this state
have given widely varying estimates of its mass
and width (from 1680 MeV to 1740 MeV for the
mass) Polyakov M.. Jafe and Wilczek predicted
a mass around 1750MeV and a width 50 larger for
these states than that of the T. S.Kabana
observes a narrow peak at 1734 0.5 5 MeV
(,hep-ex/0406032 ) width consistent with the
experimental resolution of about 6 MeV within the
errors and only a weak indication of a narrow
peak at 1693 0.5 MeV in the KS? invariant
mass. The statistical significance can be
quantified between 3 and 6 depending on cuts and
methods. If this peak corresponds to a real
particle state it would be a candidate for the N0
or the ? I1/2 pentaquark states.
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• The problem of experimental examination of
  multibaryon strange resonances was started at
  JINR, LHE from 1962 up to now. The effective mass
  spectra of 17 strange multiquark systems were
  studied for neutron exposure nC? ? X at average
  momentum 7.0 GeV/c, and this group succeeded in
  finding resonance-like peaks 1-3 only in five
  of them ? p , ? p ?, ? ? , ? ? p, ? ? ? . Most
  significant evidence was included in the Review
  of Particle Properties.
• Preliminary results4 in pC collision at 10
  GeV/c show that the obtained peaks in reports
  1-3 has been confirmed.
• 1) B.A. Shahbazian et al., Nucl. Physics,
  A374(1982),p. 73c-93.c.2) B.A. Shahbazian ,JINR
  Commun., E1-82-446,1982, International Conference
  on Hypernuclear and Kaon Physics, Heidelberg,
  1982.3) B.A. Shakhbazian et al., (Dubna, JINR).
  JINR-D1-81-107, 1981. 4. P.Z. Aslanyan,
  hep-ex/0406034,2003
• .

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2. Experiment
A reliable identification of the above
mentioned resonance needs to use 4?-detectors and
high precision measurements of the sought
objects. The bubble chamber is the most suitable
instrument for this purpose . The experimental
information of more than 700000 stereo
photographs are used to select the events with V0
strange particles at collisions protons of a 10
GeV/c momentum with propan nuclei . The GEOFIT
based on the Grind-CERN program is used to
measure the kinematics parameter of tracks
momenta(P), tg?(? - depth angle) and azimuthal
angle(?) in the photographs. The relative error
of measuring momentum p and the average track
length L of charged particles are found to be
?P/P2.1, lt Lgt12 cm for stopping particles and
?P/P 9.8 , ltLgt 36 cm for non stopping
particles. The mean values of measurement errors
for the depth and azimuthal angles are equal to
?tg? 0.0099 0.0002 and ?? 0.0052 0.0001
(rad.). The estimation of ionization, the
peculiarities of the end track points of the
stopping particles(protons, K? ) allowed one to
identify them. Protons can be identified over the
following momentum range 0.150? P ? 0.900 GeV/c.
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Identification ? and K0s
Identification ? and K0s
The events with V0 (? and Ks0) were identified
by using the following criteria 20-22 1) V0
stars from the photographs were selected
according to ???-p,Ks0 ??-? or ??ee-
hypothesis. A momentum limit of Ks0 and ? is
greater than 0.1 and 0.2 GeV/c, respectively 2)
V0 stars should have the effective mass of ? or
of Ks0 3) these V0 stars are directed to some
vertices(complanarity) 4) they should have one
vertex, a three constraint fit for the MK or M?
hypothesis and after the fit,?2should be
selected over range less than 12 5) The
analysis has shown21 that the events with
undivided ?Ks0 were assumed to be ? . 21
E.N.Kladnitskaya , K.J.Jovchev , P1-86-166
JINR,1986.
The events with V0 (? and Ks0) were identified
by using the following criteria 20-22 1) V0
stars from the photographs were selected
according to ???-p,Ks0 ??-? or ??ee-
hypothesis. A momentum limit of Ks0 and ? is
greater than 0.1 and 0.2 GeV/c, respectively 2)
V0 stars should have the effective mass of ? or
of Ks0 3) these V0 stars are directed to some
vertices(complanarity) 4) they should have one
vertex, a three constraint fit for the MK or M?
hypothesis and after the fit,?2should be
selected over range less than 12 5) The
analysis has shown21 that the events with
undivided ?Ks0 were assumed to be ? . 21
E.N.Kladnitskaya , K.J.Jovchev , P1-86-166
JINR,1986.
Distributions of ? (Armenteros parameter) and
cos??- are used for correctly identification
of the undivided V0s. ? (P?? - P - ??)/(P
?? P- ??). Where P ?? and P- ?? are the
parallel components of momenta positive and
negative charged tracks. cos ? ?- - is the
angular distribution of ?- from Ks0 decay.
Distributions of ? and cos ? ?- were
isotropic in the rest frame of Ks0 when
undivided ? Ks0 were assumed to be ? .
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Figures (a,c) and (b,d) show the effective mass
distribution of 8657-events with ?, 4122-events
with Ks0 particles and their ?2 from kinematic
fits, respectively. The expected functional form
for ?2 is depicted with the dotted histogram.
The measured masses of these events have the
following Gaussian distribution parameters MK
497.7 3.6, s.d. 23.9 MeV/c2 and M ? 1117.0
0.6, s.d.10.0 MeV/c2. The masses of the
observed ?, Ks0 are consistent with their PDG
values. The preliminary estimate of the
experimental total cross sections is equal to
3.8 0.6 mb for Ks0 production in the pC
collisions at 10 GeV/c.
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Each V0 event weighted by a factor wgeom
(1/e?), where e is the probability for
potentially observing the V0, it can be
expressed ase?? e(-Lmin/L)- e(-Lmax/L) , where
L(cp?/M) is the flight length of the V0 , Lmax
the path length from the reaction point to the
boundary of fiducial volume, and Lmin(0.5 cm) an
observable minimum distance between the reaction
point and the V0 vertex. M,?, and p are the
mass, lifetime, and momentum of the V0. The
average geometrical weights were 1.34 ?0.02 for ?
and 1.22 ?0.03 for K0s. The effective mass
resolution of the Ks0? and Ks0p systems, like
that of the ? ? ?-p system, has been measured
with a precision of ?M Ks ? ? /M Ks ?
(1.0?0.1)(Fig.). Then the effective mass
resolution of ? ? Ks0p system was estimated to
be on the average 0.6 for identified protons
with a momentum of 0.150 ?P ? 0.900 GeV/c. The
estimation of experimental inclusive cross
sections for ? and Ks0 production in the pC
collision is equal to ?? 13.3 ?1.7 mb and ?Ks0
3.8 ? 0.6 mb, respectively \cite23.
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Figure compares the momentum, cos? in the c.m.
nucleon-nucleon system, transverse momentum(pt)
and longitudinal rapidity distributions of ?
and K0s for experimental events (solid line) and
those simulated by the FRITIOF model (broken
line)in pC interactions. From Fig. one can see
that the experiment is satisfactorily described
by the FRITIOF model.
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3.Invariant mass spectrum analysis.
The total experimental background has been
obtained by three methods. In the first method,
the experimental effective mass distribution was
approximated by the polynomial function after
cutting out the resonance ranges because this
procedure has to provide the fit with ?21 and
polynomial coefficient with errors less than 30
. This distribution was fitted by the six-order
polynomial. The second of the randomly mixing
method of the angle between K0s and p for
experimental events is described in
V.L.Lyuboshits at al., JINR Rapid Comm.,
N6(74),p209, 1995. Then, these background events
were analyzed by using the same experimental
condition and the effective mass distribution (
K0sp ) was fitted by the six-order polynomial.
The analysis done by two methods has shown that
while fitting these distributions had the same
coefficients( with 20 errors) and order of
polynomial. The third background method has
been obtained by using FRITIOF model with
experimental canditions (FRITIOF, H. Pi, Comput.
Phys.Commun. 71,173, 1992.
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3.1.Ks0p - spectrum analysis
The Ks0p invariant mass distribution with a
momentum Pp ? 1.7 GeV/c (3500 combinations) is
shown in Figure. The histogram is approximated by
a polynomial background curve and by 5 resonance
curves taken in the Breit-Wigner form. The dashed
curve is the background taken in the form of a
superposition of Legendre polynomials up to the 6
-th degree, inclusive.
The Ks0p effective mass distribution for
identified protons with a momentum of 0.350? P ?
0.900 GeV/c is shown in Figure. The solid curve
is the sum of the background and 4 Breit-Wigner
resonance curves
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3.2.Ks0 ? - spectrum analysis

The Ks0? effective mass distribution for 1012
combinations is shown in Figure. The solid curve
is the sum of the background by the first method
and Breit-Wigner resonances . Similar results
have obtained when using a Breit Wigner
distribution and diferent bin sizes. There are
significant enhancements in mass regions of 1750
and 1795 MeV/c2 (Fig.). There are small
peaks in the mass regions of (1650-
1700),(1830-1860) and (1925 -1950) MeV/c2 .
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3.3. ? p - spectrum analysis
The ?p effective mass distribution for 2434
combinations for identified protons with a
momentum of 0.300? P ? 0.900 GeV/c is shown in
Figure. The solid curve is the sum of the
background by the first method and Breit-Wigner
resonances . There are significant enhancements
in mass regions of 2101, 2175 2280 and 2353
MeV/c2 (Fig.). Their excess above background by
the second method is 6.9, 4.9, 3.8 and 2.9 S.D.,
respectively.
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Conclusion

• The effective mass spectra Ks0p in
  collisions protons of a 10 GeV/c momentum with
  propan nuclei, have resulted in the discovery of
  the peaks presented below(Table 1). Table 1 shows
  the width(?) and the effective mass resonances
  which are based on the data from figure with a
  momentum range of 0.150? Pproton ? 0.900 GeV/c.
  There are small peaks in mass regions of
  1487(3.0 s.d.), 1690(3.6 s.d.) and 1980(3.0 s.d.)
  MeV/c2. The primary total cross section for
  ?(1540) production in pC3H8 interactions is
  estimated to be ? 90 ?b.

Table 1. The effective mass spectra Ks0p have
resulted in the discovery of the peaks presented
below
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• A number of peculiarities were found in the
  effective mass spectrum of system Ks0? in ranges
  of(1740-1750), (1785-1800) and (1835-1860)
  ???/?2 in collisions of protons of a 10 GeV/c
  momentum with propane nuclei(Table 2). There are
  small enhancements in the mass spectrum regions
  of (1650-1675) and (1925-1950) ???/?2. The
  prelimary total cross section for N0(1750)
  production in pC3H8 interactions is estimated
  to be ? 30 ?b.
• The N0 can be from the antidecuplet, from an
  octet (D. Diakonov, V. Petrov, hep-ph/0310212,
  V.Guzey and M.Polyakov, arXiv hep-ph/0501010,2005)
  or an 27-plet(J. Ellis et al, JHEP 0405002,
  2004, hep-ph/0401127). On the other hand, Jafe
  and Wilczek predicted a mass around 1750MeV and
  a width 50 larger for these states than that of
  the T(Phys. Rev. Lett. 91 (2003) 232003).

Table 2. The maximal statistical significance,
the full experimental width(?e) and the effective
mass of resonances in collisions of protons with
propane at 10 GeV/c.
21

• These peaks are possible candidates for two
  pentaquark states the N0 with quark content
  udsds decaying into ?K0 and the ?0 quark content
  udssd decaying into (? ?K0 )(Table 3), which are
  agreed with the calculated rotational spectra
  N0 and ?0 spectra from the theoretical report
  of D. Akers, arXiv.orghep-ex/0310014, 2004
  (below figure) and with ? spectra from the
  experimental reports of Yu.A.Troyan
  et.al.,JINR, D1-2004-39, Dubna,2004 and P.
  Aslanyan JINR, E1-2004-137,2004 (Table 2).

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Table 3. The mass of N0, ?0, ? and ? baryon
resonances in range of 1650-1900 MeV/c2 are
presented.
23

• Preliminary experimental results for S-1 ?p
  dibaryon resonances in pC? ?p X collision at 10
  GeV/c (Table 4) shows that the predicted peaks
  with the bag model has been confirmed (P.Z.
  Aslanyan, hep-ex/0406034,2003).

Table 4. The ?p effective mass spectra in
collisions of protons at 10 GeV/c and neutrons
of at 7.0 GeV/c average momentum with carbon
nuclei (B.A. Shahbazian et al., Nucl. Physics,
A374(1982),p. 73c-93.c.2).