Strangeness Neutrality Research Articles

Isentropic thermodynamics in the Polyakov–Nambu–Jona-Lasinio model

We discuss the isentropic trajectories on the QCD phase diagram in the temperature and the quark chemical potential plane using the Nambu--Jona-Lasinio model with the Polyakov loop coupling (PNJL model). We impose a constraint on the strange quark chemical potential so that the strange quark density is zero, which is the case in the ultra relativistic heavy-ion collisions. We compare our numerical results with the truncated estimates by the Taylor expansion in terms of the chemical potential to quantify the reliability of the expansion used in the lattice QCD simulation. We finally discuss the strange quark chemical potential induced by the strangeness neutrality condition and relate it to the ratio of the Polyakov loop and the anti-Polyakov loop.

The role of local and global strangeness neutrality at the inhomogeneous freeze-out in relativistic heavy ion collisions

The decoupling surface in relativistic heavy-ion collisions may not be homogeneous. Rather, inhomogeneities should form when a rapid transition from high to low entropy density occurs. We analyze the hadron "chemistry" from high-energy heavy-ion reactions for the presence of such density inhomogeneities. We show that due to the non-linear dependence of the particle densities on the temperature and baryon-chemical potential such inhomogeneities should be visible even in the integrated, inclusive abundances. We analyze experimental data from Pb+Pb collisions at CERN-SPS and Au+Au collisions at BNL-RHIC to determine the amplitude of inhomogeneities and the role of local and global strangeness neutrality.

Inhomogeneities in the freeze-out of relativistic heavy-ion collisions

An inhomogeneous decoupling surface of hadrons produced in relativistic heavy-ion collisions may occur, if the expanding hot and dense matter passes through a first order phase transition. We show that due to the non-linear dependence of the particle densities on the temperature and baryon-chemical potential such inhomogeneities should be visible even in the integrated, inclusive abundances. We analyze experimental data from Pb+Pb collisions at CERN-SPS and Au+Au collisions at BNL-RHIC to determine the amplitude of inhomogeneities and the role of local and global strangeness neutrality.

Role of global and local strangeness neutrality in an inhomogeneous freeze-out approach to relativistic heavy ion collisions

An inhomogeneous decoupling surface of hadrons produced in relativistic heavy-ion collisions may occur, if the expanding hot and dense matter passes through a first order phase transition. We show that due to the non-linear dependence of the particle densities on the temperature and baryon-chemical potential such inhomogeneities should be visible even in the integrated, inclusive abundances. We analyze experimental data from Pb+Pb collisions at CERN-SPS and Au+Au collisions at BNL-RHIC to determine the amplitude of inhomogeneities and the role of local and global strangeness neutrality.

Chemical equilibrium study in nucleus-nucleus collisions at relativistic energies

We present a detailed study of chemical freeze-out in nucleus-nucleus collisions at beam energies of $11.6A$, $30A$, $40A$, $80A$, and $158A\phantom{\rule{0.3em}{0ex}}\text{GeV}$. By analyzing hadronic multiplicities within the statistical hadronization approach, we have studied the strangeness production as a function of center-of-mass energy and of the parameters of the source. We have tested and compared different versions of the statistical model, with special emphasis on possible explanations of the observed strangeness hadronic phase space undersaturation. We show that, in this energy range, the use of hadron yields at midrapidity instead of in full phase space artificially enhances strangeness production and could lead to incorrect conclusions as far as the occurrence of full chemical equilibrium is concerned. In addition to the basic model with an extra strange quark nonequilibrium parameter, we have tested three more schemes: a two-component model superimposing hadrons coming out of single nucleon-nucleon interactions to those emerging from large fireballs at equilibrium, a model with local strangeness neutrality and a model with strange and light quark nonequilibrium parameters. The behavior of the source parameters as a function of colliding system and collision energy is studied. The description of strangeness production entails a nonmonotonic energy dependence of strangeness saturation parameter ${\ensuremath{\gamma}}_{S}$ with a maximum around $30A\phantom{\rule{0.3em}{0ex}}\text{GeV}$. We also present predictions of the production rates of still unmeasured hadrons including the newly discovered ${\ensuremath{\Theta}}^{+}(1540)$ pentaquark baryon.

An extension of the statistical bootstrap model to include strangeness

We extend the statistical bootstrap model (SBM) in order to describe hadronic systems which carry strangeness. We establish that the hadronic phase can exist only in a region of the phase space (T, , ), which is bounded by a `critical' surface. The SBM leads to a mass spectrum with the asymptotic form , where the exponent can take different values. We first employ the usual version of the SBM and impose strangeness neutrality in order to obtain the relation between the temperature and the chemical potentials , . We find an unphysical behaviour of near the critical surface. Subsequently, we study another version of SBM where and we are led to a realistic as well as acceptable behaviour. In this case we are also able to relate the parameter of the model, , (the critical temperature at zero ) with the MIT bag constant B. The relation between (T, , ) can be used to predict the particle ratios on the critical surface at the limit of the hadron gas phase.

Determination of temperature and transverse flow velocity at chemical freeze-out in relativistic nuclear interactions.

We propose a parameter-free method to determine the temperature of a thermalized state in relativistic nuclear interactions, using the experimental ${\mathrm{\ensuremath{\mu}}}_{\mathit{q}}$/T and ${\mathrm{\ensuremath{\mu}}}_{\mathit{s}}$/T values, obtained from strange particle ratios. The hadron gas formalism and strangeness neutrality are employed to relate the quark-chemical potential ${\mathrm{\ensuremath{\mu}}}_{\mathit{q}}$ and ${\mathrm{\ensuremath{\mu}}}_{\mathit{s}}$ to the temperature and thus determine its value at chemical freeze-out. This temperature, together with the inverse slope parameter from ${\mathit{m}}_{\mathit{T}}$ distributions, enable the determination of the transverse flow velocity of the fireball matter, thus disentangling the thermal and flow effects. We study several nucleus-nucleus interactions from AGS and SPS and obtain the temperature, transverse flow velocity, and quark-chemical potentials. Extrapolating the systematics we predict the values of these quantities for ongoing and future experiments at AGS, SPS, and RHIC. We discuss the possibility of reaching the conditions for quark deconfinement and QGP formation and give distinct and identifiable signature. \textcopyright{} 1996 The American Physical Society.

The Strange Neutrality: Soviet-Japanese Relations during the Second War, 1941-1945

The Strange Neutrality: Soviet-Japanese Relations during the Second War, 1941-1945

Japanese Recognition of the U.S.S.R., Soviet-Japanese Relations, 1921-1930, by George Alexander Lensen, The Strange Neutrality, Soviet-Japanese Relations during the Second World War, 1941-1945, by George Alexander Lensen, Japanese Foreign Policy on the Eve of the Pacific War. A Soviet View, by Leonid N. Kutakov

<i>Japanese Recognition of the U.S.S.R., Soviet-Japanese Relations, 1921-1930</i>, by George Alexander Lensen, <i>The Strange Neutrality, Soviet-Japanese Relations during the Second World War, 1941-1945</i>, by George Alexander Lensen, <i>Japanese Foreign Policy on the Eve of the Pacific War. A Soviet View</i>, by Leonid N. Kutakov

The Strange Neutrality: Soviet-Japanese Relations during the Second World War, 1941–1945. By George Alexander Lensen. (Tallahassee, Fla.: The Diplomatic Press, 1972. Pp. 332. $15.00.)

The Strange Neutrality: Soviet-Japanese Relations during the Second World War, 1941–1945. By George Alexander Lensen. (Tallahassee, Fla.: The Diplomatic Press, 1972. Pp. 332. $15.00.) - Volume 68 Issue 1

George Alexander Lensen: The strange neutrality: Soviet-Japanese relations during the second World War, 1941–1945. xii, 332 pp., 6 plates, 2 maps. Tallahassee, Fla.: Diplomatic Press, [1972]. $15. (English distributor: Diplomatic Press.) - Leonid N. Kutakov: Japanese foreign policy on the eve of the Pacific war: a Soviet view. Edited … by George Alexander Lensen. 241 pp. Tallahassee, Fla.: Diplomatic Press,

George Alexander Lensen: The strange neutrality: Soviet-Japanese relations during the second World War, 1941–1945. xii, 332 pp., 6 plates, 2 maps. Tallahassee, Fla.: Diplomatic Press, [1972]. $15. (English distributor: Diplomatic Press.) - Leonid N. Kutakov: Japanese foreign policy on the eve of the Pacific war: a Soviet view. Edited … by George Alexander Lensen. 241 pp. Tallahassee, Fla.: Diplomatic Press,

Japanese Foreign Policy on the Eve of the Pacific War: A Soviet View and The Strange Neutrality: Soviet-Japanese Relations during the Second World War 1941–1945

Japanese Foreign Policy on the Eve of the Pacific War: A Soviet View and The Strange Neutrality: Soviet-Japanese Relations during the Second World War 1941–1945

The Strange Neutrality: Soviet-Japanese Relations during the Second World War, 1941–1945. By George Alexander Lensen, Tallahassee: The Diplomatic Press, 1972. x, 332 pp., Illustrations, Appendix, Bibliography, Index. $15.00. - Japanese Foreign Policy on the Eve of the Pacific War: A Soviet View. By Leonid L. Kutakov. Edited with a Foreword by George Alexander Lensen, Tallahassee: The Diplomatic Press, 1972. xi,

The Strange Neutrality: Soviet-Japanese Relations during the Second World War, 1941–1945. By George Alexander Lensen, Tallahassee: The Diplomatic Press, 1972. x, 332 pp., Illustrations, Appendix, Bibliography, Index. $15.00. - Japanese Foreign Policy on the Eve of the Pacific War: A Soviet View. By Leonid L. Kutakov. Edited with a Foreword by George Alexander Lensen, Tallahassee: The Diplomatic Press, 1972. xi,

The Strange Neutrality: Soviet-Japanese Relations during the Second World War 1941–1945

The Strange Neutrality: Soviet-Japanese Relations during the Second World War 1941–1945