886 research outputs found
Current Algebras and Symmetries in Bootstrap Theory
In the first paper of this series we showed how, in the bootstrap theory, the currents associated with the
hadrons could be determined from a set of self-consistency conditions. In the present paper we show that
these "self-consistent" currents satisfy a current algebra. The proof is accomplished without recourse to any
approximate model It includes the interesting case of nonconserved currents. The convergence of sum rules
derived from current algebras is investigated in detail, and shown to be most rapid when no "nonbootstrap"
terms are present. Using these convergence properties, we discuss how and when current algebras can give
rise to hadron symmetries
General S-Matrix Methods for Calculation of Perturbations on the Strong Interactions
Recently, the authors proposed an on-the-mass-shell, S-matrix method for computing the effects of small perturbations on the masses and coupling constants of strongly interacting particles. In the present paper, the method is generalized to the multichannel case. The use of group-theoretical techniques in reducing the complexity of the method is described in detail
Equation of State in a Strongly Interacting Relativistic System
We study the evolution of the equation of state of a strongly interacting
quark system as a function of the diquark interaction strength. We show that
for the system to avoid collapsing into a pressureless Boson gas at
sufficiently strong diquark coupling strength, the diquark-diquark repulsion
has to be self-consistently taken into account. In particular, we find that the
tendency at zero temperature of the strongly interacting diquark gas to
condense into the system ground state is compensated by the repulsion between
diquarks if the diquark-diquark coupling constant is higher than a critical
value . Considering such diquark-diquark repulsion, a positive
pressure with no significant variation along the whole strongly interacting
region is obtained. A consequence of the diquark-diquark repulsion is that the
system maintains its BCS character in the whole strongly interacting region.Comment: 9 pages, 7 figs, To appear in Phys. Rev.
Experimental Restrictions on Ne'eman's Fifth Interaction
Recently, Ne'eman has proposed a "fifth interaction" between the strangeness current and a neutral vector meson χ, for the purpose of breaking SU(3) symmetry. We show that a χ mass less than 2mπ would be inconsistent with a variety of experiments, including K-mesonic atoms, the long-range pp potential, K1 regeneration from a K2 beam, the Lamb shift, modern refinements of the Cavendish "ice-bucket" experiment, and the absence of π0→γ+χ and χ→e++e-. The remaining possibility, that mχ exceeds 2mπ, is discussed briefly
Self-Consistent Determination of Coupling Shifts in Broken SU(3)
The possibility that certain patterns of SU(3) symmetry breaking are dynamically enhanced in baryon-meson couplings is studied by bootstrap methods. For the strong couplings, a single dominant enhancement is found. It produces very large symmetry-breaking terms, transforming like an octet, as often conjectured. Experimental consequences are listed, such as a reduction of K-baryon couplings relative to π-baryon couplings which is in accord with the experimental weakness of K relative to π production in many circumstances, such as photoproduction and multi-BeV cosmic-ray collisions. For parity-violating nonleptonic couplings, a dominant octet enhancement is again found, as mentioned in a previous paper, which leads to an excellent fit with experiment. For parity-conserving nonleptonic couplings, on the other hand, several different enhancements compete, and the only conclusion we can draw is that terms with the "abnormal" transformation properties brought in by strong symmetry-breaking corrections are present. Our work provides a dynamical derivation of various phenomenological facts associated with SU(6), such as the dominance of the 35 representation in parity-violating nonleptonic decays
Some general features of the bootstrap theory of octet enhancement
Some general features of the boostrap theory of octet enhancement, which can be understood without detailed calculations, are discussed. These features include: (i) the connection of this theory to the vector-mixing theory of symmetry breaking advocated by Sakurai, and to the tadpole theory of Coleman and Glashow; (ii) an understanding of why it is representations of low multiplicity that are dynamically emphasized in symmetry breaking; (iii) a demonstration that the theory remains valid when a number of assumptions made in previous applications are dropped
Weak and electromagnetic interactions of the hadrons in bootstrap theory
This is the first of a series of papers on the properties of the weak and electromagnetic currents of the hadrons in the bootstrap theory of strong interactions. In a bootstrap theory, there are many self-consistency conditions relating these weak and electromagnetic parameters to each other. We develop a formalism designed to take the fullest advantage of such bootstrap-like relations. In fact, we conjecture that the weak and electromagnetic properties of the hadrons are determined to a large extent, and perhaps completely, by self-consistency requirements. Some simple calculations of the weak and electromagnetic parameters pertaining to the octet of baryons and decuplet of resonances are given. The comparison of the results of these calculations with the experimental numbers indicates that the above conjecture holds, at least in this case
Reggeization of Pion Exchange in Production Processes
Couplings of the pion Regge trajectory are discussed. We find that the kinematic factors prescribed by Wang must be supplemented by further kinematic terms. A simple physical interpretation is given for these additional terms. Our considerations lead to a model of pion trajectory couplings, which is in reasonable agreement with those experiments on vector- and tensor-meson production in which pion exchange is expected to dominate the forward peak
Unlocking Color and Flavor in Superconducting Strange Quark Matter
We explore the phase diagram of strongly interacting matter with massless u
and d quarks as a function of the strange quark mass m_s and the chemical
potential mu for baryon number. Neglecting electromagnetism, we describe the
different baryonic and quark matter phases at zero temperature. For quark
matter, we support our model-independent arguments with a quantitative analysis
of a model which uses a four-fermion interaction abstracted from single-gluon
exchange. For any finite m_s, at sufficiently large mu we find quark matter in
a color-flavor locked state which leaves a global vector-like SU(2)_{color+L+R}
symmetry unbroken. As a consequence, chiral symmetry is always broken in
sufficiently dense quark matter. As the density is reduced, for sufficiently
large m_s we observe a first order transition from the color-flavor locked
phase to a color superconducting phase analogous to that in two flavor QCD. At
this unlocking transition chiral symmetry is restored. For realistic values of
m_s our analysis indicates that chiral symmetry breaking may be present for all
densities down to those characteristic of baryonic matter. This supports the
idea that quark matter and baryonic matter may be continuously connected in
nature. We map the gaps at the quark Fermi surfaces in the high density
color-flavor locked phase onto gaps at the baryon Fermi surfaces at low
densities.Comment: Latex with eps figures, 28 pages, minor corrections, references
update
Different Hagedorn temperatures for mesons and baryons from experimental mass spectra, compound hadrons, and combinatorial saturation
We analyze the light-flavor particle mass spectra and show that in the region
up to ~1.8GeV the Hagedorn temperature for baryons is about 30% smaller than
for mesons, reflecting the fact that the number of baryon states grows more
rapidly with the mass. We also show that the spectra are well reproduced in a
model where hadrons are compound objects of quanta, whose available number
increases with mass. The rapid growth of number of hadronic states is a
combinatorial effect. We also point out that an upper limit on the excitation
energy of these quanta results in a maximum number of hadron states that can be
formed. According to this combinatorial saturation, no more light-flavor hadron
resonances exist above a certain mass.Comment: powers in Eqs. (7,8) corrected and a reference adde
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