Modern Physics Letters A

It is suggested that, although direct measurement of pre-equilibrium reaction lifetimes cannot be carried out, blocking lifetime experiments may contain information on such intermediate processes. Numerical examples are presented for the ¹⁶O+¹²C system at 120 MeV.

It is suggested that the constituent quarks entering the SU(6)-scheme of hadrons have an explicit internal spin structure in terms of quarks and gluons. The gluonic contribution to the nucleon spin can be calculated in terms of g_A/g_V, which gives 25%. The gluonic sea is positively polarized. The recent experimental results of polarized electroproduction can be understood. Predictions about leptoproduction off neutron targets are made.

The classic Nambu-Goldstone mechanism associates massless modes to spontaneously broken symmetry. Here it is shown that spontaneous violation of a fact, such as the fact that translation generators in different directions commute, more generally implies the existence of a massless excitation. The mechanism is discussed in the context of anyon superconductivity, where it originated, and in more general contexts.

We recall the theoretical arguments that led us more than ten years ago to predict that there are only three generations. Quark-lepton mass relations (m_b/m_τ ≈ 2.8), as universally come out from unified theories at superhigh energies (close to the Planck scale), are the key point. We further argue that fractional deviations from N_ν=3 may signal new physics. The supersymmetric decay Z→ÑÑ, with Ñ the lightest neutralino and lightest supersymmetric particle (LSP), easily fits the bill. In the specific case of flipped (SU(5)×U(1)) unification, there is a strong correlation between m_t≈ O(90 ± 10) GeV, slepton masses of O(50 GeV) and the closure of the Universe due to Ñ dark matter, while ΔN_ν ≈ (0.1–0.5).

Operator product expansion (OPE) for the gluon propagator and the corresponding Slavnov-Taylor identities are discussed. Tree-level contribution of the d=4 quark and bilinear in the gluon fields condensates is calculated. It is transverse without any connection between ghost and gluon condensates. Drawbacks of the previous calculations are uncovered. It is found that there is non-zero contribution of the gauge non-invariant quark-gluon condensate.

The radiation amplitude zero in the process du→W_γ is studied as a function of the magnetic moments of the W boson (κ) and the quarks (a) where g=κ+1 and a=(g−2)12.

It is shown that the zero occurs only if both κ=1 for the W and a=0 for the quarks. This is now being tested in an experiment underway at the Tevatron (Fermilab) where κ for the W boson can be measured.

The production of two standard model Higgs bosons via the WW fusion process e⁺e⁻ → would test the predicted HHH, HWW and HHWW couplings. At TeV energies this fusion cross section dominates over that from e⁺e⁻ →ZHH and would give significant event rates for m_H ≲ 1/2 M_Z at high luminosity e⁺e⁻ colliders. We evaluate the rates and present the dynamical distributions.

We consider fermion-number violating Green’s functions involving also gauge and Higgs bosons in the axial (1+1)-dimensional Abelian Higgs model. We show that the Fourier transform of the classical vortex solution has (in the unitary gauge) an isolated pole at the position of the Higgs and gauge boson mass. In a certain sense the vortex, an Euclidean pseudoparticle, is capable to describe particles, i.e. physical gauge and Higgs bosons. From that it follows that, in the leading-order semiclassical approximation around the unit winding number vortex solution, the S-matrix elements for the fermion-number violating processes are local and of order , where ν is the vacuum expectation value and n is the number of external boson legs. This suggests that, at high energy, fermion-number violating processes with associated production of many gauge and Higgs bosons have large probabilities reaching the unitarity limit, and puts the recent observation of a similar phenomenon in the standard electroweak theory on much firmer ground.

Within the framework of an effective theory of quantum gluodynamics formulated earlier in terms of the glueball degrees of freedom, the excitations of gluon bunch formed by heavy quark and antiquark are considered. It is shown that these excitations correspond to the vibration of the gluon bunch shape and lie nearly 800 MeV higher than the charmonium ground state. The consequences of the existence of these excitations are discussed.

Loop averages and partition functions in the U(N) gauge theory are calculated for loops without intersections on arbitrary two-dimensional manifolds including nonorientable ones. The physical quantities are directly expressed through geometrical characteristics of a manifold (areas enclosed by loops and the genus) and gauge group parameters (Casimir eigenvalues and dimensions of the irreducible representations). It is shown that, from the physical quantities’ point of view, non-orientability of the manifold is equivalent to its non-compactness.