### Regular Series

#### Vol. 21 (1990), No. 3, pp. 171 – 252

Charges, Monopoles and Unit Systems

Acta Phys. Pol. B 21, 171 (1990)

page 171 •

abstract

Using an explicit notation for units, it is argued that electromagnetic fields measured by means of a charge and the corresponding fields measured by a monopole, are different physical entities. This result is related to the persistent failure of the experimental quest for monopoles.

Thermodynamics of Negative Absolute Pressures

Acta Phys. Pol. B 21, 177 (1990)

page 177 •

abstract

States with negative absolute pressure are investigated from thermodynamic viewpoint. It is found that negativity of pressure does not contradict Callen’s postulates, and the postulates cannot be extended in a natural way to rule out just these states. These states may be stable against small fluctuations. In nuclear physics, QCD and GUT, $p \lt 0$ states are easy to interpret by thermodynamics.

Instantons in QCD and Soliton Models of Hadrons

Acta Phys. Pol. B 21, 189 (1990)

page 189 •

abstract

Using an analogy to a well known soliton model of hadrons the existence of the quark sea appearing in deep inelastic lepton-hadron scattering is justified. Then using the existence of $\left \lt \bar \psi \psi \right \gt$ condensate in QCD we insert in the QCD functional integral a Lorentz scalar field which describes the quark-anti-quark pairs, and produces a dynamical mass for quarks.

Dirac Equation with Hidden Extra Spins: A Generalization of Kahler Equation. Part Two

Acta Phys. Pol. B 21, 201 (1990)

page 201 •

abstract

A sequence of equations numerated by $N = 1$, 2, 3, $\dots$ realizing the Dirac square-root procedure for spin $0 \otimes 1 \otimes \dots \frac {1}{2}N(N$ even) or $\frac {1}{2} \otimes \frac {3}{2} \otimes \dots \otimes \frac {1}{2}N(N$ odd), is further discussed. For $N = 2$ the Dfrac-type form of Kähler equation is reproduced. The equation with $N=3$ is conjectured to be physically distinguished, providing a model for fermion generations.

Finite Temperature Effect on Strings in Curved Space

Acta Phys. Pol. B 21, 209 (1990)

page 209 •

abstract

Using thermofield dynamics we study finite temperature effects on strings in curved space.

full authors' list

M. Tariq, Tauseef Ahmad, M. Zafar, M. Irfan, M.Z. Ahsan, M. Shafi

Some Angle Dependent Characteristics of Charged Shower Particles Produced at High Energies

Acta Phys. Pol. B 21, 215 (1990)

page 215 •

abstract

The angular distributions of showers in lab. and c.m. systems have been studied for various effective target thickness. Also the variation of particle number densities in lab. and c.m. systems has been given as a function of $\bar \nu$. It is observed that the particle density decreases with effective target mass in the most forward region in laboratory system whereas it shows an increasing trend in the c.m. system. The results seem to agree with CTM type of pictures of interaction. Some results on variation of $R_{\rm A}$ with in different $\eta$-intervals have also been presented.

Nuclear Matter Approach to the Heavy-Ion Optical Potential and the Proximity Approximation

Acta Phys. Pol. B 21, 223 (1990)

page 223 •

abstract

A simple theory of the heavy-ion optical potential $\cal {V}$, based on the local density approach and the frozen density model, is used to derive the energy dependent proximity approximation $\cal {V}^{\rm P}$ for the complex potential $\cal {V}$. Both $\cal {V}$ and $\cal {V}^{\rm P}$ are calculated, and the accuracy of the proximity approximation and of the scaling law implied by the approximation is tested.

Strange Matter Bubble Formation Inside Neutron Matter

Acta Phys. Pol. B 21, 245 (1990)

page 245 •

abstract

Initial stages of the phase transition of the neutron matter into strange matter at zero temperature and finite pressure are considered. Bubble formation is calculated numerically for pressures typical for a neutron star interior. The critical bubble size decreases rapidly with pressure, reaching minimum at $p \sim 20$ MeV/fm$^3$.

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