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Energy dependence of the spin-spin correlation parameter CNN at 50° and 90° c.m. for pp-elastic scattering in the energy range 0.69–0.95 GeV
Volume 99B, number 1
PHYSICS LETTERS
ENERGY DEPENDENCE OF THE SPIN-SPIN CORRELATION PARAMETER AT 50 ° AND 90 ° c.m. FOR pp-ELASTIC SCATTERING
5 February 1981
CNN
IN THE ENERGY RANGE 0 . 6 9 - 0 . 9 5 GeV V.A. EFIMOVYH, A.I. KOVALEV, V.V. POIAAKOV, V.E. POPOV, A.N. PROKOFIEV, A.V. SHVEDCHIKOV, V.Yu. TRAUTMAN, V.G. VOVCHENKO and A.A. ZHDANOV Leningrad Nuclear Physics Institute of the Academy of Sciences of the USSR, Gatchina, 188350, USSR and N.S. BORISOV, M.Yu. KAZARINOV, Yu.M. KAZARINOV, Yu.F. KISELEV, M.Yu. LIBURG, B.S. NEGANOV and Yu.A. USOV Joint Institute for Nuclear Research, Moscow, 101000, USSR Received 3 July 1980
The spin-spin correlation parameter CNN at 50° and 90° c.m. for elastic pp-scattering has been obtained in the energy range 0.69-0.95 GeV. It was found that the parameter CNN (90°) shows resonance-like structure at energies near 700 MeV. Its energy dependence does not agree with Hoshizaki's phase-shift analysis predictions. CNN(50°) agrees well with these predictions and does not show any structure within the accuracy of the measurements.
P r o t o n - p r o t o n scattering for various spin directions has recently been investigated in several experiments [ 1 - 4 ] . These measurements display a striking dependence o f the pp-interactionon the directions of the spins and point to possible evidence for a dibaryon resonance. Measuring the fixed-angle energy dependence of the polarization parameters in pp-scattering is a sensitive way to verify this assumption. On the other hand, 90 ° c.m. is a special point where purespin interactions could be investigated with great success. We studied the fixed-angle energy dependence of CNNat 50 ° and 90 ° c.m. in the energy region 0 . 6 9 0.95 GeV using the polarized proton beam from the LNPI synchrocyclotron and a frozen spin polarized target [5]. The external proton beam from the accelerator (1 GeV, 1/~A) was scattered from a beryllium target at 0 = (7.5 + 0.2) ° to produce a 0.95 GeV polarized proton beam. Polarized proton beams with different energies were obtained by using CH absorbers and a special magnetic channel for shaping the beams. The direction o f the beam polarization was changed by 28
rotating the scattering plane by 180 °. The layout used in this experiment is shown in fig. 1. The polarization of the beam was measured using the beam polarimeter with CH 2 and C (background) targets. The polarization (PB) was obtained at every beam energy by measur!ng the left-right asymmetry for pp-elastic scattering at 45 ° c.m. It was then calculated using the equation PB -
1 L-R , Ppp L + R
(1)
where Ppp is the polarization in the pp-elastic scattering. The values o f Ppp were derived by averaging the Ppp world data in the energy range of 0 . 5 - 1 . 2 GeV at o 0 cm "~"90 . We also had a possibility to obtain the PB data in an independent way from the measurements of CNN [see eq. (2)]. Both sets of data were in agreement within their errors. The polarized proton beam was scattered on the polarized target made of propanediol doped with
0 0 3 1 - 9 1 6 3 / 8 1 / 0 0 0 0 - 0 0 0 0 / $ 02.50 © North-Holland Publishing Company
Volume 99B, number 1
PHYSICS LETTERS
5 February 1981
$2 $5 MWPC
'~2~"
4
So M
M
CN2 S, 52 S~
W/////////A
,--I-+4VERTICAL PLANE
ss+
)<-" \
\
Fig. 1. Layout of the experiment. The polarized beam passes from left to right through the CH2 target and its polarization is estimated by measuring the asymmetry of the pp-elastic scattering at 45° c.m. (sP-sP). The beam then goes through the collimator and scatters in the polarized proton target (PT). The elastic events are counted by the counters S1-$8. The beam monitors are BM (sB-s B) and VM (sM-sM). The proportional chambers MWPCmonitor the beam shape and position.
Table 1 Polarized proton beam intensities and measurements of the beam polarization. The quoted errors include statistical errors and errors due to uncertainty in pp-scattering polarization (<~2.5%).I denotes the beam intensity on target. Tlab (MeV)
I (#-1)
690 -+ 30 760 + 30 804 + 23 892 +-20 950 +- 17
2.4 x 7.6 × 6.8 x 1.3 × 9.0 x
PB 105 l0 s l0 s 106 106
0.284 0.291 0.290 0.300 0.300
-+0.006 +-0.007 -*0.006 -+0.008 -+0.008
K2Cr20 7 . The target polarization (PT) was measured via a NMR system with a precision of about 3%. The last figure was examined using direct measurements on the JINR synchrocyclotron unpolarized proton beam [12]. The average polarization during the experiment was 90%. The target was operated at t = 0.04 K. The directions of the beam and target polarization were orthogonal to the scattering plane. Scintillation counter telescopes were used for measurements of 50 ° and 90 ° c.m. pp-elastic scattering intensities. They were placed at kinematically conjugate angles and detected scattered and recoiling particles. Their positions were calculated taking into account the deflection of the particles in the magnetic field (2.6 T) of the target. The angular acceptance of the
detecting system was A0 = 9.7 ° for (0) = 90 ° and A0 = 5.6 ° for (0> = 50 ° (all angles are taken in the center of mass system). The background subtraction was carried out using d u m m y target measurements. The level of the background made up 0 . 2 5 - 0 . 3 8 % of the rate and was estimated with a relative precision of about 1.5%. The beam relative intensity was monitored by BM and VM monitors which were placed up- and downstream of the polarized target: the former registered the direct beam particles, and the latter viewed elastic pp-scattering on the CH 2 target at 30 ° c.m. in the vertical plane. Its position was adjusted taking into account beam deflections in the field at every beam momentum. The s u m L + R was also used as a monitor. The shape and angular divergence of the beam, and its position on the target, were controlled by proportional chambers MWPC. The beam position and angular divergence were constant within + 1 mm and +0.03 ° during the whole run. Possible systematic errors due to variations of the beam parameters were reduced by reversing the beam polarization after collecting 5 X 103 events. We have collected the data in each of the four initial polarization states (+PB, +-PT). The total number of events is greater than 104 for any polarization combination at each energy. The s p i n - s p i n correlation parameter CNN and po29
Volume 99B, number 1
PHYSICS LETTERS
5 February 1981
Table 2 The spin-spin correlation parameter CNN and polarization in pp-elastic scattering at 50 ° and 90 ° c.m. The quoted errors include statistical errors and errors due to uncertainty in PB and PT. Tlab (MeV)
CNN (50 ° )
Ppp(50 ° )
ppp(50 °) a)
CNN(90o)
ppp(90 o )
690 760 804 892 950
0.54 0.52 0.60 0.55 0.54
0.525 0.475 0.484 0.430 0.410
0.516 0.493 0.468 0.423 0.407
0.735 0.66 0.52 0.61 0.52
-0.020 -0.049 0.10 -0.002 -0.027
+- 0.03 +- 0.03 -+0.04 -+0.03 -+0.03
a) The averaged world data [6].
-+0.014 -+ 0.016 -+ 0.014 ± 0.011 -+ 0.010
+-0.030 -+0.04 -+0.06 b) +-0.04 +- 0.03
+-0.007 -+0.007 +- 0.02 b) +- 0.007 -+0.006
b) This result was obtained at <0 > = 85 ° c.m.
larization in pp-elastic scattering were obtained using the equations
1
+-0.009 -+0.008 +-0.008 -+0.009 -+0.010
(X÷+ + X _ _ ) - ( X _ + +X÷_)
CNN - PBPT (N++ +N__) + (IV_+ +N+_) '
(2a)
2(N++ - X _ _ ) PPP = (PB + P T ) [(N++ + N _ _ ) +
(AT_+ + N + _ ) ] '
(2b)
where _+ -+ refers to b e a m and target polarization. We see f r o m table 2 that the values o f P p p ( 5 0 ° ) '
agree well w i t h the averaged world data. The Ppp(90 °) are near zero as we had to expect. The value Ppp = 0.1 +- 0.02 at T = 0.804 G e V was obtained at 0 = 85 ° c.m. and does not contradict the value at nearby energies [6]. This indicates the lack o f i m p o r t a n t systematic errors in our experiment. The results are presented in fig. 2 in comparison w i t h predictions o f Hoshizaki's phase-shift analysis [7] in which the existence o f the 1 D2 and 3F 3 resonances was taken into consideration. The energy d e p e n d e n c e o f CNN(90 °) shows a
CNI 0=90 °
e=5o o
QSO
i
~-wORLD DAT.t61
~-N.& BORISOV ~ -TI'IIS EXI~
I
600
I
I 'I000
I
I 1400
I 600
I t~o
A
"r/Mlev/ 1400
Fig. 2. The spin-spin correlation parameter CNN in 50 ° and 90 ° c.m. pp-elastic scattering is plotted against the incident proton kinetic energy in the laboratory system along with earlier measurements. The smaU black points and the line are Hoshizaki's phaseshift analysis predictions [7].
30
Volume 99B, number 1
PHYSICS LETTERS
5 February 1981
- T.A.MI/I.£RA ~ - WORLI)I)ATA[63 - -
1.0
,~- D.e[SSETet al. 0.8-
(~- ~ts.~oR,sov et al.--
Tills EXP.
0.60A-
0.2-
~
"'% . . . . °
I
0.5
I
1
I
1.5
cg
I
2
I
2.5
t c v/c
-0.2--
Fig. 3. The data of the spin-spin correlation parameters CNNand
broad maximum near T = 0.7 GeV. This dependence does not agree with the predictions o f the analysis cited before especially in the region of T > 0.8 GeV. The experimental data do not confirm the increase o f the CNN(90°) value to 0.95 near 1 GeV. The difference between the phase-shift analysis predictions and the data is greater than four experimental errors. On the other hand, the features of the energy dependence do not contradict the existence of the 3F 3 resonance. The decrease o f CNN at p I> 1.4 GeV/c is consistent with a partial wave 3F~ having resonance behaviour and interference between 3F 3 and 3p states [7]. Comparison with the results recently obtained b y the Rice university group [8] shows a reasonable agreement except their result at p = 1.3 GeV/c where the difference is nearly four experimental errors. It should be noted that this CNN value is smaller than all results obtained in this region before. The agreement of our data with the results of earlier experiments at similar energies is quite good. The CNN(50°) data do not show any structure in the region o f investigation and satisfy the predictions of the analysis. Fig. 3 shows CNN(90°), CLL (90 °) data. We observe a similar structure in both curves. The shapes of the
CLL at 90 ° c.m. The curve is a hand-drawn line to guide the eye. energy dependences o f the s p i n - s p i n correlation parameters CNN and CLL in the m o m e n t u m region o f 1 - 2 . 5 GeV/c and the positions o f the maxima are nearly the same. It is possible to conclude from this that the term I 0 [CNN(90°) -- CLL(90°)] = [MIoI 2 [9] does not reveal a resonant-like behaviour within the errors o f the experiments. The smooth decrease o f this term in the range 1.2 < p < 2 GeV/c is connected only with the very well known behaviour o f the differential cross section at 90 ° c.m. i n t h i s region. The term MI0 depend s only on odd partial waves with J--- L + 1 and contains neither 3F 3 nor 3P 1 states. On the other hand, the parameters CNN(90°) and CLL(90 °), taken separately, include the matrix elements MSS, M01 which depend on the states with J = L ( 1D2, 3F3, 3P 1). The resonances in the 1D2 and 3F 3 states are established rather well [10,11 ]. The resonance in the 3p state was discussed in Yokosawa's latest reports [ 11 ] where its parameters were predicted ( ~ - = 2.18 GeV, T ~ 0.66 GeV). It was also shown that there was a good chance that either 3P 0 or 3P 1 might be resonating. We must suppose because of the lack o f resonant-like behaviour o f the M10 term, that if the P resonance exists, only the 3P 1 state can be responsible for this. 31
Volume 99B, number 1
PHYSICS LETTERS
We wish to t h a n k Professors N. Hoshizaki and A. Yokosawa for sending us their results.
References [1 ] E.K. Biegert et al., Phys. Lett. 73B (1978) 235. [2] I.P. Auer et al., Phys. Lett. 67B (1977) 113; 70B (1978) 475. [3] I.P. Auer et al., Phys. Rev. Lett. 41 (1978) 1436; 41 (1978) 354; A. Lin et al., Phys. Lett. 74B (1978) 273. [4] H. Spinka, Argonne report ANL-HEP-CP-78-56; AIP Conf. Proc. Vol. 51 (1978) p. 382. [5] N.S. Borisov et al., JINR reports 13-10253, 13-10257 (1976).
32
5 February 1981
[6] J. Bystricky and F. Lehar, Nucleon-nucleon scattering data (Karlsruhe, 1978). [7] N. Hoshizaki, Prog. Theor. Phys. 60 (1978) 1796; 61 (1979) 129. [8] T.A. Mulera, AIP Conf. Proc. Vol. 51 (1978) p. 428 [9] N. Itoshizaki, Suppl. Prog. Theor. Phys. 12 (1968) 107. [ 10 ] K. Hidaka, Argonne report ANL-HEP-CP-78-15; W. Grein and P. Kroll, Nucl. Phys. B137 (1978) 173. [11 ] A. Yokosawa, Argonne reports ANL-HEP-CP-80-01, ANL-HEP-CP-80-07. [12] N.S. Borisov et al., JINR report P1-10755 (1977). [13] D. Besset et al., AIP Conf. Proc. Vol. 51 (1978) p. 424. [14] H.B. Willard et al., AIP Conf. Proc. Vol. 51 (1978) p. 420.
PHYSICS LETTERS
ENERGY DEPENDENCE OF THE SPIN-SPIN CORRELATION PARAMETER AT 50 ° AND 90 ° c.m. FOR pp-ELASTIC SCATTERING
5 February 1981
CNN
IN THE ENERGY RANGE 0 . 6 9 - 0 . 9 5 GeV V.A. EFIMOVYH, A.I. KOVALEV, V.V. POIAAKOV, V.E. POPOV, A.N. PROKOFIEV, A.V. SHVEDCHIKOV, V.Yu. TRAUTMAN, V.G. VOVCHENKO and A.A. ZHDANOV Leningrad Nuclear Physics Institute of the Academy of Sciences of the USSR, Gatchina, 188350, USSR and N.S. BORISOV, M.Yu. KAZARINOV, Yu.M. KAZARINOV, Yu.F. KISELEV, M.Yu. LIBURG, B.S. NEGANOV and Yu.A. USOV Joint Institute for Nuclear Research, Moscow, 101000, USSR Received 3 July 1980
The spin-spin correlation parameter CNN at 50° and 90° c.m. for elastic pp-scattering has been obtained in the energy range 0.69-0.95 GeV. It was found that the parameter CNN (90°) shows resonance-like structure at energies near 700 MeV. Its energy dependence does not agree with Hoshizaki's phase-shift analysis predictions. CNN(50°) agrees well with these predictions and does not show any structure within the accuracy of the measurements.
P r o t o n - p r o t o n scattering for various spin directions has recently been investigated in several experiments [ 1 - 4 ] . These measurements display a striking dependence o f the pp-interactionon the directions of the spins and point to possible evidence for a dibaryon resonance. Measuring the fixed-angle energy dependence of the polarization parameters in pp-scattering is a sensitive way to verify this assumption. On the other hand, 90 ° c.m. is a special point where purespin interactions could be investigated with great success. We studied the fixed-angle energy dependence of CNNat 50 ° and 90 ° c.m. in the energy region 0 . 6 9 0.95 GeV using the polarized proton beam from the LNPI synchrocyclotron and a frozen spin polarized target [5]. The external proton beam from the accelerator (1 GeV, 1/~A) was scattered from a beryllium target at 0 = (7.5 + 0.2) ° to produce a 0.95 GeV polarized proton beam. Polarized proton beams with different energies were obtained by using CH absorbers and a special magnetic channel for shaping the beams. The direction o f the beam polarization was changed by 28
rotating the scattering plane by 180 °. The layout used in this experiment is shown in fig. 1. The polarization of the beam was measured using the beam polarimeter with CH 2 and C (background) targets. The polarization (PB) was obtained at every beam energy by measur!ng the left-right asymmetry for pp-elastic scattering at 45 ° c.m. It was then calculated using the equation PB -
1 L-R , Ppp L + R
(1)
where Ppp is the polarization in the pp-elastic scattering. The values o f Ppp were derived by averaging the Ppp world data in the energy range of 0 . 5 - 1 . 2 GeV at o 0 cm "~"90 . We also had a possibility to obtain the PB data in an independent way from the measurements of CNN [see eq. (2)]. Both sets of data were in agreement within their errors. The polarized proton beam was scattered on the polarized target made of propanediol doped with
0 0 3 1 - 9 1 6 3 / 8 1 / 0 0 0 0 - 0 0 0 0 / $ 02.50 © North-Holland Publishing Company
Volume 99B, number 1
PHYSICS LETTERS
5 February 1981
$2 $5 MWPC
'~2~"
4
So M
M
CN2 S, 52 S~
W/////////A
,--I-+4VERTICAL PLANE
ss+
)<-" \
\
Fig. 1. Layout of the experiment. The polarized beam passes from left to right through the CH2 target and its polarization is estimated by measuring the asymmetry of the pp-elastic scattering at 45° c.m. (sP-sP). The beam then goes through the collimator and scatters in the polarized proton target (PT). The elastic events are counted by the counters S1-$8. The beam monitors are BM (sB-s B) and VM (sM-sM). The proportional chambers MWPCmonitor the beam shape and position.
Table 1 Polarized proton beam intensities and measurements of the beam polarization. The quoted errors include statistical errors and errors due to uncertainty in pp-scattering polarization (<~2.5%).I denotes the beam intensity on target. Tlab (MeV)
I (#-1)
690 -+ 30 760 + 30 804 + 23 892 +-20 950 +- 17
2.4 x 7.6 × 6.8 x 1.3 × 9.0 x
PB 105 l0 s l0 s 106 106
0.284 0.291 0.290 0.300 0.300
-+0.006 +-0.007 -*0.006 -+0.008 -+0.008
K2Cr20 7 . The target polarization (PT) was measured via a NMR system with a precision of about 3%. The last figure was examined using direct measurements on the JINR synchrocyclotron unpolarized proton beam [12]. The average polarization during the experiment was 90%. The target was operated at t = 0.04 K. The directions of the beam and target polarization were orthogonal to the scattering plane. Scintillation counter telescopes were used for measurements of 50 ° and 90 ° c.m. pp-elastic scattering intensities. They were placed at kinematically conjugate angles and detected scattered and recoiling particles. Their positions were calculated taking into account the deflection of the particles in the magnetic field (2.6 T) of the target. The angular acceptance of the
detecting system was A0 = 9.7 ° for (0) = 90 ° and A0 = 5.6 ° for (0> = 50 ° (all angles are taken in the center of mass system). The background subtraction was carried out using d u m m y target measurements. The level of the background made up 0 . 2 5 - 0 . 3 8 % of the rate and was estimated with a relative precision of about 1.5%. The beam relative intensity was monitored by BM and VM monitors which were placed up- and downstream of the polarized target: the former registered the direct beam particles, and the latter viewed elastic pp-scattering on the CH 2 target at 30 ° c.m. in the vertical plane. Its position was adjusted taking into account beam deflections in the field at every beam momentum. The s u m L + R was also used as a monitor. The shape and angular divergence of the beam, and its position on the target, were controlled by proportional chambers MWPC. The beam position and angular divergence were constant within + 1 mm and +0.03 ° during the whole run. Possible systematic errors due to variations of the beam parameters were reduced by reversing the beam polarization after collecting 5 X 103 events. We have collected the data in each of the four initial polarization states (+PB, +-PT). The total number of events is greater than 104 for any polarization combination at each energy. The s p i n - s p i n correlation parameter CNN and po29
Volume 99B, number 1
PHYSICS LETTERS
5 February 1981
Table 2 The spin-spin correlation parameter CNN and polarization in pp-elastic scattering at 50 ° and 90 ° c.m. The quoted errors include statistical errors and errors due to uncertainty in PB and PT. Tlab (MeV)
CNN (50 ° )
Ppp(50 ° )
ppp(50 °) a)
CNN(90o)
ppp(90 o )
690 760 804 892 950
0.54 0.52 0.60 0.55 0.54
0.525 0.475 0.484 0.430 0.410
0.516 0.493 0.468 0.423 0.407
0.735 0.66 0.52 0.61 0.52
-0.020 -0.049 0.10 -0.002 -0.027
+- 0.03 +- 0.03 -+0.04 -+0.03 -+0.03
a) The averaged world data [6].
-+0.014 -+ 0.016 -+ 0.014 ± 0.011 -+ 0.010
+-0.030 -+0.04 -+0.06 b) +-0.04 +- 0.03
+-0.007 -+0.007 +- 0.02 b) +- 0.007 -+0.006
b) This result was obtained at <0 > = 85 ° c.m.
larization in pp-elastic scattering were obtained using the equations
1
+-0.009 -+0.008 +-0.008 -+0.009 -+0.010
(X÷+ + X _ _ ) - ( X _ + +X÷_)
CNN - PBPT (N++ +N__) + (IV_+ +N+_) '
(2a)
2(N++ - X _ _ ) PPP = (PB + P T ) [(N++ + N _ _ ) +
(AT_+ + N + _ ) ] '
(2b)
where _+ -+ refers to b e a m and target polarization. We see f r o m table 2 that the values o f P p p ( 5 0 ° ) '
agree well w i t h the averaged world data. The Ppp(90 °) are near zero as we had to expect. The value Ppp = 0.1 +- 0.02 at T = 0.804 G e V was obtained at 0 = 85 ° c.m. and does not contradict the value at nearby energies [6]. This indicates the lack o f i m p o r t a n t systematic errors in our experiment. The results are presented in fig. 2 in comparison w i t h predictions o f Hoshizaki's phase-shift analysis [7] in which the existence o f the 1 D2 and 3F 3 resonances was taken into consideration. The energy d e p e n d e n c e o f CNN(90 °) shows a
CNI 0=90 °
e=5o o
QSO
i
~-wORLD DAT.t61
~-N.& BORISOV ~ -TI'IIS EXI~
I
600
I
I 'I000
I
I 1400
I 600
I t~o
A
"r/Mlev/ 1400
Fig. 2. The spin-spin correlation parameter CNN in 50 ° and 90 ° c.m. pp-elastic scattering is plotted against the incident proton kinetic energy in the laboratory system along with earlier measurements. The smaU black points and the line are Hoshizaki's phaseshift analysis predictions [7].
30
Volume 99B, number 1
PHYSICS LETTERS
5 February 1981
- T.A.MI/I.£RA ~ - WORLI)I)ATA[63 - -
1.0
,~- D.e[SSETet al. 0.8-
(~- ~ts.~oR,sov et al.--
Tills EXP.
0.60A-
0.2-
~
"'% . . . . °
I
0.5
I
1
I
1.5
cg
I
2
I
2.5
t c v/c
-0.2--
Fig. 3. The data of the spin-spin correlation parameters CNNand
broad maximum near T = 0.7 GeV. This dependence does not agree with the predictions o f the analysis cited before especially in the region of T > 0.8 GeV. The experimental data do not confirm the increase o f the CNN(90°) value to 0.95 near 1 GeV. The difference between the phase-shift analysis predictions and the data is greater than four experimental errors. On the other hand, the features of the energy dependence do not contradict the existence of the 3F 3 resonance. The decrease o f CNN at p I> 1.4 GeV/c is consistent with a partial wave 3F~ having resonance behaviour and interference between 3F 3 and 3p states [7]. Comparison with the results recently obtained b y the Rice university group [8] shows a reasonable agreement except their result at p = 1.3 GeV/c where the difference is nearly four experimental errors. It should be noted that this CNN value is smaller than all results obtained in this region before. The agreement of our data with the results of earlier experiments at similar energies is quite good. The CNN(50°) data do not show any structure in the region o f investigation and satisfy the predictions of the analysis. Fig. 3 shows CNN(90°), CLL (90 °) data. We observe a similar structure in both curves. The shapes of the
CLL at 90 ° c.m. The curve is a hand-drawn line to guide the eye. energy dependences o f the s p i n - s p i n correlation parameters CNN and CLL in the m o m e n t u m region o f 1 - 2 . 5 GeV/c and the positions o f the maxima are nearly the same. It is possible to conclude from this that the term I 0 [CNN(90°) -- CLL(90°)] = [MIoI 2 [9] does not reveal a resonant-like behaviour within the errors o f the experiments. The smooth decrease o f this term in the range 1.2 < p < 2 GeV/c is connected only with the very well known behaviour o f the differential cross section at 90 ° c.m. i n t h i s region. The term MI0 depend s only on odd partial waves with J--- L + 1 and contains neither 3F 3 nor 3P 1 states. On the other hand, the parameters CNN(90°) and CLL(90 °), taken separately, include the matrix elements MSS, M01 which depend on the states with J = L ( 1D2, 3F3, 3P 1). The resonances in the 1D2 and 3F 3 states are established rather well [10,11 ]. The resonance in the 3p state was discussed in Yokosawa's latest reports [ 11 ] where its parameters were predicted ( ~ - = 2.18 GeV, T ~ 0.66 GeV). It was also shown that there was a good chance that either 3P 0 or 3P 1 might be resonating. We must suppose because of the lack o f resonant-like behaviour o f the M10 term, that if the P resonance exists, only the 3P 1 state can be responsible for this. 31
Volume 99B, number 1
PHYSICS LETTERS
We wish to t h a n k Professors N. Hoshizaki and A. Yokosawa for sending us their results.
References [1 ] E.K. Biegert et al., Phys. Lett. 73B (1978) 235. [2] I.P. Auer et al., Phys. Lett. 67B (1977) 113; 70B (1978) 475. [3] I.P. Auer et al., Phys. Rev. Lett. 41 (1978) 1436; 41 (1978) 354; A. Lin et al., Phys. Lett. 74B (1978) 273. [4] H. Spinka, Argonne report ANL-HEP-CP-78-56; AIP Conf. Proc. Vol. 51 (1978) p. 382. [5] N.S. Borisov et al., JINR reports 13-10253, 13-10257 (1976).
32
5 February 1981
[6] J. Bystricky and F. Lehar, Nucleon-nucleon scattering data (Karlsruhe, 1978). [7] N. Hoshizaki, Prog. Theor. Phys. 60 (1978) 1796; 61 (1979) 129. [8] T.A. Mulera, AIP Conf. Proc. Vol. 51 (1978) p. 428 [9] N. Itoshizaki, Suppl. Prog. Theor. Phys. 12 (1968) 107. [ 10 ] K. Hidaka, Argonne report ANL-HEP-CP-78-15; W. Grein and P. Kroll, Nucl. Phys. B137 (1978) 173. [11 ] A. Yokosawa, Argonne reports ANL-HEP-CP-80-01, ANL-HEP-CP-80-07. [12] N.S. Borisov et al., JINR report P1-10755 (1977). [13] D. Besset et al., AIP Conf. Proc. Vol. 51 (1978) p. 424. [14] H.B. Willard et al., AIP Conf. Proc. Vol. 51 (1978) p. 420.