Modern Physics Letters A

We argue that the recent CLEO-c data on e⁺e^- annihilation into pairs of charmed mesons at c.m. energy around 4.0 GeV are not well described by a single resonance ψ(4040), but can be better understood if there is an additional narrow resonance with mass within few MeV from the threshold.

We consider one-loop effective action of SU(3) QCD with a most general constant chromomagnetic (chromoelectric) background which has two independent Abelian field components. The effective potential with a pure magnetic background has a local minimum only when two Abelian components and of color magnetic field are orthogonal to each other. The nontrivial structure of the effective action has important implication in estimating quark–gluon production rate and p_T-distribution in quark–gluon plasma. In general the production rate depends on three independent Casimir invariants, in particular, it depends on the relative orientation between chromoelectric fields.

A seldom recognized fundamental difficulty undermines the concept of individual "state" in the present formulations of quantum statistical mechanics (and in its quantum information theory interpretation as well). The difficulty is an unavoidable consequence of an almost forgotten corollary proved by Schrödinger in 1936 and perused by Park, Am. J. Phys.36, 211 (1968). To resolve it, we must either reject as unsound the concept of state, or else undertake a serious reformulation of quantum theory and the role of statistics. We restate the difficulty and discuss a possible resolution proposed in 1976 by Hatsopoulos and Gyftopoulos, Found. Phys.6, 15; 127; 439; 561 (1976).

The so-called Stueckelberg transformation is introduced as a prescription of minimal coupling following the procedure of the Utiyama theory, for both internal and spacetime symmetry Lie groups. As a natural example, the theory is applied to the Weyl group and the corresponding gauge gravitational theory is developed. This context appears to be a natural source to account for some sort of dark matter intrinsically related to the gauge-group parameter associated with scale transformations.

The contribution of the cosmological constant to the ground state energy of the quantum vacuum field has been investigated in the framework of the Casimir energy calculation. A regularization scheme is suggested. The equation of state and the nature of the corresponding medium has been studied with some interesting observations.

We study the associated production of the neutral top-pion with the third family quarks within the context of the topcolor-assisted technicolor model at the hadron colliders. The studies show that, at the Tevatron, the cross-sections of all these processes are too small to produce enough identified signals. But the cross-sections can be largely enhanced at the LHC. Specially for the processes and , the cross-sections can reach the level of a few hundred fb even a few pb for the light neutral top-pion. With the high yearly luminosity 100 fb^-1 at the LHC, over 10⁴ signals can be produced via the above two processes. There exists an ideal flavor-changing mode to detect neutral top-pion, i.e. , because the SM background of such production mode are very clean. Therefore, we can conclude that neutral top-pion should be observable at the LHC via the processes and . On the other hand, the statistics available at the LHC via these two processes might be enough to measure the Yukawa couplings and . Finally, it must be noted that the study of the process can give us a good chance to distinguish the TC2 model from the SM and MSSM because there does not exist such similar tree-level favor-changing process in these models.

We study the SO(1, 1) dark energy model with the inverse power law potential, V = V₀Φ^-n, and find for n<2 the model has the late-time phantom property and the universe will evolve to the future Big Rip. The inverse linear potential is a special case, for which the field and the scalar factor are respectively T-invariant and CT-invariant about the Big Rip.