122 research outputs found
Rapidity particle spectra in sudden hadronization of QGP
We show that the remaining internal longitudinal flow of colliding quarks in
nuclei offers a natural explanation for the diversity of rapidity spectral
shapes observed in Pb--Pb 158AGeV nuclear collisions. Thus QGP sudden
hadronization reaction picture is a suitable approach to explain the rapidity
spectra of hadrons produced.Comment: 3 pages including 2 figure
Bruno Touschek: particle physicist and father of the electron-positron collider
This article gives a brief outline of the life and works of the Austrian
physicist Bruno Touschek, who conceived, proposed and, 50 years ago, brought to
completion the construction of AdA, the first electron-positron storage ring.
The events which led to the approval of the AdA pro ject and the Franco-Italian
collaboration which con- firmed the feasibility of electron-positron storage
rings will be recalled. We shall illustrate Bruno Touschek's formation both as
a theoretical physicist and as an expert in particle accelerators during the
period be- tween the time he had to leave the Vienna Staat Gymnasium in 1938,
because of his Jewish origin from the maternal side, until he arrived in Italy
in the early 1950s and, in 1960, proposed to build AdA, in Frascati. The events
which led to Touschek's collaboration with Rolf Wideroe in the construction of
the first European betatron will be de- scribed. The article will make use of a
number of unpublished as well as previously unknown documents, which include an
early correspon- dence with Arnold Sommerfeld and Bruno Touschek's letters to
his family in Vienna from Italy, Germany and Great Britain. The impact of
Touschek's work on students and collaborators from University of Rome will be
illustrated through his work on QED infrared radiative corrections to high
energy e+e- experiments and the book Meccanica Statistica.Comment: To be published in EPJ
The ideal relativistic spinning gas: polarization and spectra
We study the physics of the ideal relativistic rotating gas at
thermodynamical equilibrium and provide analytical expressions of the momentum
spectra and polarization vector for the case of massive particles with spin 1/2
and 1. We show that the finite angular momentum J entails an anisotropy in
momentum spectra, with particles emitted orthogonally to J having, on average,
a larger momentum than along its direction. Unlike in the non-relativistic
case, the proper polarization vector turns out not to be aligned with the total
angular momentum with a non-trivial momentum dependence.Comment: Final published version. Minor corrections to formula
Counting valence quarks at RHIC and LHC
We consider the Nuclear Modification Ratios in heavy ion collisions, R_CP and
R_AA, in the region of intermediate transverse momentum, and study the
dependency upon the constituent quark composition of the observed hadron.
Adopting a two component recombination/fragmentation model, validated by
experimental information from STAR and PHENIX, we show that a clear distinction
is predicted for the f0(980) between the assumptions of or
diquark-antidiquark content.Comment: 14 pages, 11 eps figures, added figures and minor corrections, to
appear in Phys. Lett.
An extension of the Statistical Bootstrap Model to include Strangeness. Implications on Particle Ratios
The Statistical Bootstrap Model (SBM) is extended to describe hadronic
systems which carry the quantum number of strangeness. The study is conducted
in the three-dimensional space of temperature, up-down and strange chemical
potentials, wherein the existence of a ``critical'' surface is established,
which sets the limits of the hadronic phase of matter. A second surface,
defined by the null expectation value of strangeness number is also determined.
The approach of the latter surface to the critical one becomes the focal point
of the present considerations. Two different versions of the extended SBM are
examined, corresponding to the values 2 and 4 for the exponent, which
determines the asymptotic fall-off of the mass spectrum. It is found that the
version with the value 4 has decisive physical advantages. This model is
subsequently adopted to discuss (strange) particle ratios pertaining to
multiparticle production processes, for which a thermal equilibrium mode of
description applies.Comment: 29 pages, 38 figures, all the figures are joined in one file.
accepted for publication in Phys. Rev.
Pauli letter collection: letter to Wolfgang Pauli
Touschek suggests building isotopic spin into a 4-component spinor theory. He discusses invariance of a theory and construction of an approximate "Heisenberg theory"
Pauli letter collection: letter to Wolfgang Pauli
Touschek agrees with the introduction of a new index in Pauli's theory. He writes about the discrete mass spectrum in the field-free case as function of total isotopic spin
Pauli letter collection: letter to Wolfgang Pauli
Touschek writes about a paper by Jensen and Steck
Pauli letter collection: letter to Wolfgang Pauli
Touschek comments a part of Pauli's lecture in Varenna, which is superscribed "The nucleon magnetic moment in the static theory"
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