444
R. Stock
parameters [362], once more experimental information becomes available, as can
be expected.
7.9.6.4 Production of Light Nuclei in A + A Collisions
At RHIC and LHC, a large number of light nuclei and antinuclei have been measured [325, 363, 364], from deuterium to anti-alpha. This continues a tradition dating
back to BEVALAC time [365] and SPS [366]. Dating back is also the controversy
concerning model description or, alternatively stated, the lack of a comprehensive
understanding [325, 364, 367]. The Statistical Hadronization Model(SHM) gives a
very good description(hadro-chemical freeze-out) of the LHC yields [325], along
with all other hadron multiplicities. The coalescence model [365, 367] addresses
the end of the hadron/resonance expansion stage (kinetic freeze-out), whence the
produced nucleons, spread out in phase space, overlap, to a certain degree, with
the internal wave functions of the various clusters. There are difficulties in both
views if one takes them literally. The clusters cannot have existed at 160 MeV, the
hadronization temperature. On the other hand, the coalescence cannot proceed onshell because of the cluster binding energies (that are ignored in the model). All this
points to a deeper flaw in, either the models, or their conventional understanding.
The role of quantum mechanics seems to be missing, as pointed out long ago by E.
Remler [368]. Hadronization does not directly produce a decoherent, on-shell state,
in A + A collisions. If hadronization occurs via the quantum mechanical decay
of initially produced colour singlet clusters (see Sect. 5.3.3), then Fermis Golden
Rule refers to the phase space weights AFTER decoherence. And, in fact, in the
SHM partition functions we employ the set of in-vacuo free masses of the produced
particles, also for the clusters, with apparent success. One might then speculate
that the number densities and their ratios are fixed by the entropy at hadronization,
but we have to wait until after the freeze-outs to have them decohere. This is a
speculation, of course.
References
1. W. Weise, Proc. Intern. School Enrico Fermi, Course 43, edit. A. Molinari and L. Riccati, IOS
Press Amsterdam 2003, p. 473;
A. W. Thomas and W. Weise, The Structure of the Nucleon, Wiley-VCH publ. 2001
2. E. V. Shuryak, Phys. Rept. 61 (1980) 71;
B. Müller, The Physics of the Quark-Gluon-Plasma, Springer Lecture Notes in Physics
Vol.225, 1985;
L. McLerran, The Physics of the Quark-Gluon Plasma, Rev. Mod. Phys.58 (1986) 1012
3. B. A. Freedman and L. McLerran, Phys. Rev. D16 (1977) 1169;
E. V. Shuryak, Zh. Eksp. Teor. Fiz.74 (1978) 408;
J. I. Kapusta, Nucl. Phys. B148 (1979) 461
4. L. Susskind, Phys. Rev. D20 (1979) 2610
5. J. Kuti, J. Polonyi and K. Szalachanyi, Phys. Lett. B98 (1981) 199
R. Stock
parameters [362], once more experimental information becomes available, as can
be expected.
7.9.6.4 Production of Light Nuclei in A + A Collisions
At RHIC and LHC, a large number of light nuclei and antinuclei have been measured [325, 363, 364], from deuterium to anti-alpha. This continues a tradition dating
back to BEVALAC time [365] and SPS [366]. Dating back is also the controversy
concerning model description or, alternatively stated, the lack of a comprehensive
understanding [325, 364, 367]. The Statistical Hadronization Model(SHM) gives a
very good description(hadro-chemical freeze-out) of the LHC yields [325], along
with all other hadron multiplicities. The coalescence model [365, 367] addresses
the end of the hadron/resonance expansion stage (kinetic freeze-out), whence the
produced nucleons, spread out in phase space, overlap, to a certain degree, with
the internal wave functions of the various clusters. There are difficulties in both
views if one takes them literally. The clusters cannot have existed at 160 MeV, the
hadronization temperature. On the other hand, the coalescence cannot proceed onshell because of the cluster binding energies (that are ignored in the model). All this
points to a deeper flaw in, either the models, or their conventional understanding.
The role of quantum mechanics seems to be missing, as pointed out long ago by E.
Remler [368]. Hadronization does not directly produce a decoherent, on-shell state,
in A + A collisions. If hadronization occurs via the quantum mechanical decay
of initially produced colour singlet clusters (see Sect. 5.3.3), then Fermis Golden
Rule refers to the phase space weights AFTER decoherence. And, in fact, in the
SHM partition functions we employ the set of in-vacuo free masses of the produced
particles, also for the clusters, with apparent success. One might then speculate
that the number densities and their ratios are fixed by the entropy at hadronization,
but we have to wait until after the freeze-outs to have them decohere. This is a
speculation, of course.
References
1. W. Weise, Proc. Intern. School Enrico Fermi, Course 43, edit. A. Molinari and L. Riccati, IOS
Press Amsterdam 2003, p. 473;
A. W. Thomas and W. Weise, The Structure of the Nucleon, Wiley-VCH publ. 2001
2. E. V. Shuryak, Phys. Rept. 61 (1980) 71;
B. Müller, The Physics of the Quark-Gluon-Plasma, Springer Lecture Notes in Physics
Vol.225, 1985;
L. McLerran, The Physics of the Quark-Gluon Plasma, Rev. Mod. Phys.58 (1986) 1012
3. B. A. Freedman and L. McLerran, Phys. Rev. D16 (1977) 1169;
E. V. Shuryak, Zh. Eksp. Teor. Fiz.74 (1978) 408;
J. I. Kapusta, Nucl. Phys. B148 (1979) 461
4. L. Susskind, Phys. Rev. D20 (1979) 2610
5. J. Kuti, J. Polonyi and K. Szalachanyi, Phys. Lett. B98 (1981) 199