Negative-ParityNNResonances and Extraneous States

Abstract

Angular momentum excitations of six quarks in a bag give a rich resonance structure in the NN channel above P^ab -1.3 GeV/c. Some states occur with quantum numbers foreign to NN^ which we refer to as extraneous states. The lowest negative-parity states are an (NNj^P^ resonance and two extraneous 7 = 0 states with J^ = 0" and 2", all around 2.2 GeV. The latter two states mainly decay in NN'K. The lowest (NN)^F3 resonance lies at M=2.34GeV.Increasing experimental evidence^ for some resonances in the NN system is being reported. The results on pp scattering with polarized targets and beams above P-^^ 1 GeY/c show a surprisingly rich structure. Analyses^^ of these/)/) data indicate the existence of a resonance in one of the imcoupled spin-triplet partial waves {^P^, ^Fg,...) at M ^ 2.3 GeV and possibly also a resonance in one of the spin-singlet states {^SQ,^D2, ...) aroundM ^2A GeV. Angular distributions and polarizations indicate that the ^F^ assignment for this uncoupled spin-triplet state is favored. Deuteron photodisintegration experiments^ give evidence for a resonance around 2.38 GeV.Conventionally^ one tries to explain these resonances as strong interactions with a channel coupled to the NN channel. A (not too deeply) bound state in the coupled channel will show up as a resonance in NN, in the neighborhood of the threshold for that channel. We note that the NN system cannot have the quantum numbers 1 = 0, J^ = 0'^,0", 2",4",... and/=l, J^= 1+, S"', 5*, We call states with those quantum numbers extraneous to the NN channel and will denote them by Xjjp. Recently Jaffe^ proposed a quite novel type of resonance. He indicated the possible existence of boxmd states of six quarks in a bag. One assumes here the quarks to be in s states of a spherical bag. These resonances necessarily have positive parity. One finds 1=1 resonances in the ^SQ (M = 2.17 GeV) and ^D^ (M = 2.36 GeV) waves and 7=0 resonances in the ^S^ (M =2.24 GeV) and ^D^ (M = 2.36 GeV) waves.The masses of these states which contain iNr= 6 nonstrange quarks can be calculated in the spherical-bag approximation in which the mass operator is given bywhere B= 59.2 MeV fm"^ Zo= 363 MeV fm, and a^= 2.20 are the parameters determined from the g^ and qq spectrum."^ The nonstrange-quark energy is measured by a" = 403 MeV fm and the color magnetic-interaction strength by MQO= 34.9 MeV fm. The color magnetic mass splitting is determined byF^ is the color SU(3) quadratic Casimir operator. In the bag model the mass of a colorless state is found by minimizing the eigenvalue of the mass

Measurement of the Difference inpnTotal Cross Sections in Pure Longitudinal Spin States

“…5 The isospin-0 channel is of particular interest also because this channel cannot couple to NA or TTD channels which have been discussed in connection with the interpretation of the pp(J= 1) case near threshold. 8 Furthermore the thresholds for JVAT*(1400) and A A (1236) are higher than 1.5 GeV/c (1.7 and 2.1 GeV/c, respectively).…”

On the quark structure of the lightest nuclei

“…Energy spectrum of 12q system centroids of splitted supermultiplets". The internal structure of these supermultiplets (say, orbital momentum splitting) may probably be described, in terms of the deformed rotating bags [29], etc.…”

Search for flavoured multiquark states in a simple bag model

“…This led to speculations on states bound essentially by the coherent effect of hyperfine forces (also called chromomagnetic forces). A systematic study of chromomagnetism for multiquarks was carried out by de Swart et al [6,7], and further developed by several authors [18][19][20]. We shall use their techniques and results along this work.…”

“…It is impossible to list all relevant references. Let us mention, for instance: in the "Hexaquark" or dibaryon sector, the pioneering work by Jaffe on the H particle (ssuudd) [5], and subsequent studies by the Nijmegen group [6,7]; in the 5-quark sector, again the work of the Nijmegen group [6,7] or, more recently by Lipkin and the Grenoble group on the flavoured pentaquark [8]; in the 4-quark sector, the numerous speculations about scalar mesons [9] or the observation that flavour-independence inevitably leads to stable tetraquark states (QQqq) if the mass ratio m(Q)/m(q) is large enough [10].…”