Exotic narrow resonance searches in the KExotic narrow resonance searches in the K ss

00 system system

in pin p+propane +propane interactions atinteractions at 1 10 GeV/c0 GeV/c Petros Aslanyan 1,2,†Petros Aslanyan 1,2,†

(1) Joint Institute for Nuclear Research.(1) Joint Institute for Nuclear Research.(2) Yerevan State University . † paslanian@jinr.ru.(2) Yerevan State University . † paslanian@jinr.ru.

Introduction.Introduction. Method.Method.

( ( KK ss00 ) ) - - spectrum spectrum

analysis analysis..Conclusion. Conclusion.

Workshop on Hadron Structure at J-PARCNovember 30 – December 2, 2005, Tsukuba, Ibaraki, Japan.

High Energy Accelerator Research Organization (KEK)

c.f.(1405): uudsu or uds

e.g. uuddc, uussd

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.

Qqqqq

Example: uudds

Baryon number = 1/3 + 1/3 + 1/3 + 1/3 – 1/3 = 1

Strangeness = 0 + 0 + 0 + 0 + 1 = 1

Meson （ q q ）

Baryon （ q q q ）

[1] D. Diakonov, V. Petrov, and M. Polyakov (Z. Phys. A 359 ,305 ,1997 ) and [2] V.Guzey and M.Polyakov(arXiv hep-ph/0501010,2005) predicted and studied antidecuplet baryons by using the chiral soliton (Skyrme) models. The lightest member of the pentaquarks antidecuplet has positive strangeness, the mass of M=1530 MeV/c2.

•Exotic: S= +1Exotic: S= +1Results from a wide range of experiments are consistent with the existence of an exotic S=+1 resonance, the +(1540) with a narrow width and a mass near 1540 MeV . Results from this experiment:Results from this experiment:M M + = (1540 = (15408) 8) MeV/c2, + =(9.2 1.8) 1.8) MeV/c2.PDG-04: + =(9.2 0.3)0.3) MeV/c2.

Multi-quark states, glueballs and hybrids have been searched for experimentally for a very long time, but none is established.

Evidence for Penta-Quark StatesSpring8 ELSA

JLab-p

HERMES

ITEP

pp ++.

COSY-TOFDIANA

SVD/IHEP

JLab-d

ZEUSCERN/NA49

H1

Nomad

this experimentthis experiment

Negative Results

ΞΞ----(1862)(1862)

Also evidence for Also evidence for ΞΞ00(1862)(1862)

( ( I = 3/2I = 3/2 ) )

NA49

)a

)b

)c

)d

)( M

ussdd

dssdu

dudss

uddss 8.5:~

69

18

21862

ceSignifican

N

MeV

MeVM

event

)/( BSS

)))) dcba

)( M

pp collision at Ecm=17.2GeV

S.Kabana from STAR collaboration observed 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 * I=1/2 pentaquark states.Studies (Polyakov M.) 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). Jaffe and Wilczek predicted a mass around 1750MeV and a width 50% larger for these states than that of the Θ+.

•Exotic: S= 0Exotic: S= 0Low mass: 1710 MeVLow mass: 1710 MeVNarrow width: < 40 MeVNarrow width: < 40 MeVJp=1/2+[1]Jp=1/2+[1]

A reliable identification of the above mentioned resonance needs to use 4-detectors and highprecision 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/P=2.1%, < L>=12 cm for stopping particles and P/P =9.8 %, <L>= 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.

2. Experiment

Beam

The events with V0 ( and Ks0) were

identified by using the following criteria : 1) V0 stars from the photographs were selected according to -+p,Ks

0 -+

or e++e- hypothesis. A momentum limit of Ks

0 and is greater than 0.1 and 0.2 GeV/c, respectively ; 2) V0 stars should have the effective mass of or of Ks

0; 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, 2 should be selected over range less than 12; 5) The analysis has shown[21] that the events with undivided Ks

0 were assumed to be (Fig.) . [21] E.N.Kladnitskaya , K.J.Jovchev , P1-86-166 JINR,1986.

Identification and K0s

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 V0 decay in rest frame V0 . Distributions of and cos *

- were isotropic in the

rest frame of Ks0 when undivided Ks

0 were assumed to be .

Identification and K0s

Figures (a,c) and (b,d) show the effective mass distribution of 8657-events with , 4122-events with Ks

0 particles and their 2 from kinematic fits, respectively. The expected functional form for 2 isdepicted 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 , Ks

0 are consistent with their PDG values. The preliminary estimate of the experimental total cross sections is equal to 3.8 ± 0.6 mb for Ks

0 production in the p+C collisions at 10 GeV/c.

Each V0 event weighted by a factor wgeom (=1/e), where e is the probability for potentially observing the V0, it can be expressed as:e = 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 minimumdistance 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 K0

s.The effective mass resolution of the Ks

0 system, like that of the -+p system, has been measured with a precision of ( M Ks ) /M Ks =(1.00.1)%(Fig.).The estimation of experimental inclusive cross sections for and Ks

0 production in the p+C collision is equal to =13.3 1.7 mb and Ks0 = 3.8 0.6 mb, respectively .

Figure compares the momentum, cos in the c.m. nucleon-nucleon system, transverse momentum(pt) and longitudinal rapidity distributions of andK0

s for experimental events (solid line) and those simulated by the FRITIOF model (broken line)in p+C interactions. From Fig. one can see that the experiment is satisfactorily described by the FRITIOF model.

( K s0 ) - 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 2=1 and polynomial coefficient with errors less than 10 %. The second of the randomly mixing method of the angle between K0

s and 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 was fitted by the polynomial function. The analysis done by two methods has shown that while fitting these distributions had the same coefficients( with 10 % errors) and order of polynomial.The third background method has been obtained by using FRITIOF modelwith experimental canditions (FRITIOF, H. Pi, Comput. Phys.Commun. 71,173, 1992).Hereinafter , the Ks

0 effective mass distribution for 1012 combinations is shown on Figure (next slide). The solid curve is the sum of the background by the first method and 2 Breit-Wigner resonance in Figure. The values for the mean position of the peak and the width obtained by using Breit Wigner fits . The statistical significance for the fit on Fig. inside a mass window is calculated as NP /(NB)1/2, where NB is the number of counts in the background fit under the peak and NP is the number of counts in the peak.

There are significant enhancements in mass regions of 1750 and 1795 MeV/c2 (Fig.). Their excess above background by the first method is 5.8 and 3.3 S.D., respectively. There are small enhancements in the mass regions of (1650- 1700),(1830-1860) and (1925 -1950) MeV/c2 . This bin size of 18 MeV/c2 is agreed with the experimental resolution.

a

This analysis of background by FRITIOF shows too that the simulated events could not imitate peaks with mass of 1750 and 1795 MeV/c2.

Hereinafter, analyses of effective mass distributions have obtained similarly when using a Breit Wigner distribution and different bin sizes.

There are significant enhancements in mass regions of (1750 17), (179521) and (1835 20)MeV/c2 with bin size 10 MeV/c2 (Fig.). Their excess above background by the first method is 4.0, 2.7 , 3.0 S.D.. There is small enhancement in mass region of 1935 MeV/c2.

We show a lot of statistical deviations except only over the range of 1750 MeV/c2 on Figure because there are not a enough statistics in bins of 6.5 MeV/c2 size. There is the significant peak in the mass region of (1750 16) MeV/c2. Their excess above background by the first method is 4.5 S.D..

There is the significant peak in the mass region of (1742 14) MeV/c2 with bin size 21 MeV/c2 (Fig.). Their excess above background by the first method is equal to 5.0 S.D.. Figure shows insignificant deviations in mass regions of 1670, 1795, 1855 and 1935 MeV/c2 because this bin size is done larger than experimental resolution.

The figure shows the invariant mass distributions of ( K0s) with bin size 11 MeV/c2 . There are enhancements in the mass regions 1670, 1750, 1795 and 1850MeV/c2. Their excess above background by the first method is 2.9, 4.7 , 2.3 and 2.4 S.D..

ConclusionConclusion A number of peculiarities were found in the effective mass spectrum of system A number of peculiarities were found in the effective mass spectrum of system KKss

00 in ranges in ranges of:((1650-1675 ),(1740-1750), (1785-1800), (1835-1860) and (1925-1950) МэВ/сof:((1650-1675 ),(1740-1750), (1785-1800), (1835-1860) and (1925-1950) МэВ/с2 2 in c in collisions ollisions of of protons with propanprotons with propanee nuclei nuclei atat momentum 10 GeV/c momentum 10 GeV/c.. There are significant enhancements in There are significant enhancements in the mass spectrum with bin size 18 МэВ/сthe mass spectrum with bin size 18 МэВ/с2 2 only in regions of 1750 and 1795 МэВ/с only in regions of 1750 and 1795 МэВ/с2 2 (Table 1).(Table 1).

The prThe prelelimary total cross section for imary total cross section for NN00(1(1750750) production in p+C) production in p+C33HH88 interactions is estimated to interactions is estimated to be be 3030 bb..

The NThe N00 can be from the antidecuplet, from an octet (D. Diakonov, V. Petrov, hep-ph/0310212, can be from the antidecuplet, from an octet (D. Diakonov, V. Petrov, hep-ph/0310212, V.Guzey and M.Polyakov, arXiv hep-ph/0501010,2005V.Guzey and M.Polyakov, arXiv hep-ph/0501010,2005) or an 27-plet(J. Ellis et al, JHEP 0405:002, ) or an 27-plet(J. Ellis et al, JHEP 0405:002, 2004, hep-ph/0401127).2004, hep-ph/0401127). On the other hand, Jaffe and Wilczek predicted a mass around 1750MeV On the other hand, Jaffe and Wilczek predicted a mass around 1750MeV and a width 50% larger for these states than that of the Θ+(Pand a width 50% larger for these states than that of the Θ+(Phys. Rev. Lett. hys. Rev. Lett. 91 91 (2003) (2003) 232003).232003).

ResonanceResonance

decay modedecay mode

M M MM

(MeV/c(MeV/c22))

ExperimentalExperimental

Width Width e e The maximal The maximal

statistical statistical significancesignificance

00ss 175017501818 32 32 6 6 14 14 6 6 5.85.8

00ss 1795 1795 1919 44 44 1515 24241515 3.33.3

Table 1. 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.

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 ), which are agreed: with the calculated rotational spectra N0 and 0 spectra for antidecuplet from theoretical report of D. Akers, arXiv.org:hep-ex/0310014, 2004 (below Table); ) 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 (next slide ).

PreliminaryPreliminary proposal proposal The study of the structure of The study of the structure of elementary particles and atomic elementary particles and atomic

nucleusnucleus at J-PARK at J-PARK..

Exotic multi-quark hadrons with B=0,1,2,3 and S=+1,0,-1,-2 strangeness will be to search in systems from Ks

0 and particles for protron-nucleus interactions at beam momenta of 4-50 GeV/c. A statistical significance of identified resonances would be to improve. As a test would be to use the experimental data fron 2 m propane bubble chamber.

EExperimental regularities xperimental regularities forfor K Kss00 , , ,, and and strange strange particles particles

productionproductionss and and theirs exotic theirs exotic decays decays will will study study in in protron-nucleus protron-nucleus interactioninteractionss at beam moment at beam momenta of a of 4-4-550 GeV/c.0 GeV/c. For instance will be to For instance will be to study ratios of multiplicities for these strange particles on the study ratios of multiplicities for these strange particles on the + multiplicity in central ranges as a probe for searching QGP. in central ranges as a probe for searching QGP.