arXiv subjects
Publications and source records attributed to Qi-Ren Zhang.
A sharply peaked structure is found in the angular distribution of emitted $π^+$ mesons from the photon-proton collisions. It offers a possible way for generating a $π^+$-condensation in free space. To make the stimulated emission of $π^+$-mesons efficient, a ring resonator is designed.
The possibility of $γ-$ray laser generation by the radiation of wiggling electrons in an usual background laser is discussed.
Quantum electrodynamics in a laser is formulated, in which the electron-laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron-laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of $γ-$ray laser generation by use of this kind of collision is discussed.
By relativity we show that, although the superluminal motion of classical particles is forbidden, the superluminal transportation of quanta of any massive matter field is possible. Exact theoretical derivation and precise numerical computation are presented. To search the superluminal phenomena is therefore still meaningful.
We propose a quantization procedure for the nucleon-scalar meson system, in which an arbitrary mean scalar meson field $ϕ$ is introduced. The equivalence of this procedure with the usual ones is proven for any given value of $ϕ$. By use of this procedure, the scalar meson field in the Walecka's RMFT and in Chin's RHA are quantized around the mean field. Its corrections on these theories are considered by perturbation up to the second order. The arbitrariness of $ϕ$ makes us free to fix it at any stage in the calculation. When we fix it in the way of Walecka's RMFT, the quantum corrections are big, and the result does not converge. When we fix it in the way of Chin's RHA, the quantum correction is negligibly small, and the convergence is excellent. It shows that RHA covers the leading part of quantum field theory for nuclear systems and is an excellent zeroth order approximation for further quantum corrections, while the Walecka's RMFT does not. We suggest to fix the parameter $ϕ$ at the end of the whole calculation by minimizing the total energy per-nucleon for the nuclear matter or the total energy for the finite nucleus, to make the quantized relativistic mean field theory (QRMFT) a variational method.
We consider the statistical irreversibility and its compatibility with the reversible dynamics. The role played by the observation is analyzed in detail. It makes our previous proof for the second law of thermodynamics clearer. On this basis, we emphasize the importance and wide applicability for the second law of thermodynamics. A new form of physics with this law being substituted by the principle of information conservation is suggested. By the way, we also solve the paradox of Schrödinger cat, and show that the universe will not go to the so-called heat death spontaneously.
We show that the principle of entropy increase may be exactly founded on a few axioms valid not only for quantum and classical statistics, but also for a wide range of statistical processes.
We show that the conservation and the non-additivity of the information, together with the additivity of the entropy make the entropy increase in an isolated system. The collapse of the entangled quantum state offers an example of the information non-additivity. Nevertheless, the later is also true in other fields, in which the interaction information is important. Examples are classical statistical mechanics, social statistics and financial processes. The second law of thermodynamics is thus proven in its most general form. It is exactly true, not only in quantum and classical physics but also in other processes, in which the information is conservative and non-additive.
We show that if the laser is intense enough, it may always ionize an atom or induce transitions between discrete energy levels of the atom, no matter what is its frequency. It means in the quantum transition of an atom interacting with an intense laser of circular frequency $ω$, the energy difference between the initial and the final states of the atom is not necessarily being an integer multiple of the quantum energy $\hbarω$. The absorption spectra become continuous. The Bohr condition is violated. The energy of photoelectrons becomes light intensity dependent in the intense laser photoelectric effect. The transition probabilities and cross sections of photo-excitations and photo-ionizations are laser intensity dependent, showing that these processes cannot be reduced to the results of interactions between the atom and separate individual photons, they are rather the processes of the atom interacting with the laser as a whole. The interaction of photons on atoms are not simply additive. The effects are non-perturbative and non-linear. Some numerical results for processes between hydrogen atom and intense circularly polarized laser, illustrating the non-perturbative and non-linear character of the atom-laser interaction, are given.
The potential energy surface of the H13 proton in base cytosine of the DNA molecules is calculated {\it ab initio} at the Gaussian98 MP2/6-311G(d,p) level. Two potential wells are found. One corresponds to the normal cytosine, while the other corresponds to its imino tautomer. The bindings of the proton in these wells are stable enough against the thermo-disturbance. The motions of the proton in these wells are oscillations around the nearest nitrogen atom like the pendula, and may move far away from the nitrogen atom to form the hydrogen bond with other bases. The estimated tunneling probability of the H13 proton from one well to another well shows that the life time of the proton staying in one of these wells is about 6$\times10^2$ yr. It is too long to let tautomers of cytosine be in thermodynamical equilibrium in a room temperature gas phase experiment. The biological significance of these result is discussed.
We show that the non-locality together with the statistical character makes the world statistically separable. The super-luminal signal transmission is impossible. The quantum theory is therefore consistent with the relativity and the causality.
We show that in the quantum transition of a system induced by the interaction with an intense laser of circular frequency $ω$, the energy difference between the initial and the final states of the system is not necessarily being an integer multiple of the quantum energy $\hbarω$.
We show that the collapse of the entangled quantum state makes the entropy increase in an isolated system. The second law of thermodynamics is thus proven in its most general form.
We study a thermodynamically consistent implementation of the nucleon volume in the mean field theory, and find that this volume has large consequences on the properties of hadronic matter under extreme conditions such as in astrophysical objects and high energy heavy-ion collisions. It is shown that we can reproduce the critical temperature $T_{c}\simeq 200$ MeV predicted by lattice QCD calculations for the phase transition from hadronic matter to quark-gluon plasma, by using parameters which are adjusted to fit all empirical data for normal nuclear matter.
It is shown that in both the gluonic and strange sea explanations of the Ellis-Jaffe sum rule violation discovered by the European Muon Collaboration (EMC), the spin of the proton, when viewed in in its rest reference frame, could by fully provided by quarks and antiquarks within a simple quark model picture, taken into account the relativistic effect from the Wigner rotation.
We confirmed the following idea by numerical calculation: The extended structure of baryons may make the nuclear equation of state stiffer at higher density while keeping the compression modulus for normal nuclear matter around its empirical value $K=240MeV$.The model built in this wayy fits all empirical data for normal nuclear matter and gives the mass limit of neutron stars compatible with the observation.