2,352 research outputs found
A fundamental test of the Higgs Yukawa coupling at RHIC in A+A collisions
Searches for the intermediate boson, , the heavy quantum of the Weak
Interaction, via its semi-leptonic decay, , in the 1970's instead
discovered unexpectedly large hadron production at high , notably ,
which provided a huge background of from internal and external
conversions. Methods developed at the CERN ISR which led to the discovery of
direct-single- in 1974, later determined to be from the semi-leptonic
decay of charm which had not yet been discovered, were used by PHENIX at RHIC
to make precision measurements of heavy quark production in p-p and Au+Au
collisions, leading to the puzzle of apparent equal suppression of light and
heavy quarks in the QGP. If the Higgs mechanism gives mass to gauge bosons but
not to fermions, then a proposal that all 6 quarks are nearly massless in a
QGP, which would resolve the puzzle, can not be excluded. This proposal can be
tested with future measurements of heavy quark correlations in A+A collisionsComment: 12 pages, 16 figures, 26th Winter Workshop on Nuclear Dynamics, Ocho
Rios, Jamaica WI, January 2-9, 2010. Corrected citation of 1974 direct single
lepton discover
Hadronic centrality dependence in nuclear collisions
The kaon number density in nucleus+nucleus and p+p reactions is investigated
for the first time as a function of the initial energy density and
is found to exhibit a discontinuity around =1.3 GeV/fm. This
suggests a higher degree of chemical equilibrium for
1.3 GeV/fm. It can also be interpreted as reflection of the same
discontinuity, appearing in the chemical freeze out temperature (T) as a
function of . The dependence of (u,d,s) hadrons,
whith N the number of participating nucleons, also indicates a high degree of
chemical equilibrium and T saturation, reached at 1.3 GeV/fm.
Assuming that the intermediate mass region (IMR) dimuon enhancement seen by
NA50 is due to open charm (), the following observation can be made:
a) Charm is not equilibrated. b) suppression -unlike
- appears also in S+A collisions, above 1
GeV/fm. c) Both charm and strangeness show a discontinuity near the same
. d) could be formed mainly through coalescence.
e) The enhancement factors of hadrons with u,d,s,c quarks may be connected in a
simple way to the mass gain of these particles if they are produced out of a
quark gluon plasma (QGP). We discuss these results as possible evidence for the
QCD phase transition occuring near 1.3 GeV/fm.Comment: 4 pages, 4 figures, proceedings of Vth International Conference on
Strangeness in Quark Matter, 20-25 July 2000, Berkeley, California. To appear
in Journal of Physics G: Nuclear and Particle Physic
Recent results in relativistic heavy ion collisions: from ``a new state of matter'' to "the perfect fluid"
Experimental Physics with Relativistic Heavy Ions dates from 1992 when a beam
of 197Au of energy greater than 10A GeV/c first became available at the
Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL)
soon followed in 1994 by a 208Pb beam of 158A GeV/c at the Super Proton
Synchrotron (SPS) at CERN (European Center for Nuclear Research). Previous
pioneering measurements at the Berkeley Bevalac in the late 1970's and early
1980's were at much lower bombarding energies (~ 1 A GeV/c) where nuclear
breakup rather than particle production is the dominant inelastic process in
A+A collisions. More recently, starting in 2000, the Relativistic Heavy Ion
Collider (RHIC) at BNL has produced head-on collisions of two 100A GeV beams of
fully stripped Au ions, corresponding to nucleon-nucleon center-of-mass energy,
sqrt(sNN)=200 GeV, total c.m. energy 200A GeV. The objective of this research
program is to produce nuclear matter with extreme density and temperature,
possibly resulting in a state of matter where the quarks and gluons normally
confined inside individual nucleons (r < 1 fm) are free to act over distances
an order of magnitude larger. Progress from the period 1992 to the present will
be reviewed, with reference to previous results from light ion and
proton-proton collisions where appropriate. Emphasis will be placed on the
measurements which formed the basis for the announcements by the two major
laboratories: "A new state of matter", by CERN on Feb 10, 2000 and "The perfect
fluid", by BNL on April 19, 2005.Comment: 62 pages, 39 figures. Review article published in Reports on Progress
in Physics on June 23, 2006. In this published version, mistakes,
typographical errors, and citations have been corrected and a subsection has
been adde
Asexual and sexual replication in sporulating organisms
This paper develops models describing asexual and sexual replication in
sporulating organisms. Replication via sporulation is the replication strategy
for all multicellular life, and may even be observed in unicellular life (such
as with budding yeast). We consider diploid populations replicating via one of
two possible sporulation mechanisms: (1) Asexual sporulation, whereby adult
organisms produce single-celled diploid spores that grow into adults
themselves. (2) Sexual sporulation, whereby adult organisms produce
single-celled diploid spores that divide into haploid gametes. The haploid
gametes enter a haploid "pool", where they may recombine with other haploids to
form a diploid spore that then grows into an adult. We consider a haploid
fusion rate given by second-order reaction kinetics. We work with a simplified
model where the diploid genome consists of only two chromosomes, each of which
may be rendered defective with a single point mutation of the wild-type. We
find that the asexual strategy is favored when the rate of spore production is
high compared to the characteristic growth rate from a spore to a reproducing
adult. Conversely, the sexual strategy is favored when the rate of spore
production is low compared to the characteristic growth rate from a spore to a
reproducing adult. As the characteristic growth time increases, or as the
population density increases, the critical ratio of spore production rate to
organism growth rate at which the asexual strategy overtakes the sexual one is
pushed to higher values. Therefore, the results of this model suggest that, for
complex multicellular organisms, sexual replication is favored at high
population densities, and low growth and sporulation rates.Comment: 8 pages, 5 figures, to be submitted to Journal of Theoretical
Biology, figures not included in this submissio
Do Search for Dibaryonic De - Excitations in Relativistic Nuclear Reactions
Some odd characteristics are observed in the single particle distributions
obtained from interactions at momenta which are
explained as the manifestation of a new mechanism of strangeness production via
dibaryonic de-excitations. A signature of the formation of hadronic and
baryonic clusters is also reported. The di-pionic signals of the dibaryonic
orbital de-excitations are analyzed in the frame of the MIT - bag Model and a
Monte Carlo simulation.The role played by the dibaryonic resonances in
relativistic nuclear collisions could be a significant one.
Key words: Relativistic nuclear interactions negative pions, negative kaons,
di-pions , streamer chamber, dibaryons, MIT - bag model
PACS codes: 25.75.+r,14.40.Aq,14.20.Pt,12.40.AsComment: 17 pages,LATEX, preprint ICTP -243 1993,figures available by reques
Supergravity and the jet quenching parameter in the presence of R-charge densities
Following a recent proposal, we employ the AdS/CFT correspondence to compute
the jet quenching parameter for N=4 Yang-Mills theory at nonzero R-charge
densities. Using as dual supergravity backgrounds non-extremal rotating branes,
we find that the presence of the R-charges generically enhances the jet
quenching phenomenon. However, at fixed temperature, this enhancement might or
might not be a monotonically increasing function of the R-charge density and
depends on the number of independent angular momenta describing the solution.
We perform our analysis for the canonical as well as for the grand canonical
ensemble which give qualitatively similar results.Comment: 18 pages, 2 figures; v3: clarifying comments added, references added,
version to appear in JHE
Offenders' Crime Narratives across Different Types of Crimes
The current study explores the roles offenders see themselves playing during an offence and their relationship to different crime types. One hundred and twenty incarcerated offenders indicated the narrative roles they acted out whilst committing a specific crime they remembered well. The data were subjected to Smallest Space Analysis (SSA) and four
themes were identified: Hero, Professional, Revenger and Victim in line with the recent theoretical framework posited for Narrative Offence Roles (Youngs & Canter, 2012). Further analysis showed that different subsets of crimes were more like to be associated with different narrative offence roles. Hero and Professional were found to be associated with property offences (theft, burglary and shoplifting), drug offences and robbery and Revenger
and Victim were found to be associated with violence, sexual offences and murder. The theoretical implications for understanding crime on the basis of offenders' narrative roles as well as practical implications are discussed
The Importance of Time Congruity in the Organisation.
In 1991 Kaufman, Lane, and Lindquist proposed that time congruity in terms of an individual's time preferences and the time use methods of an organisation would lead to satisfactory performance and enhancement of quality of work and general life. The research reported here presents a study which uses commensurate person and job measures of time personality in an organisational setting to assess the effects of time congruity on one aspect of work life, job-related affective well-being. Results show that time personality and time congruity were found to have direct effects on well-being and the influence of time congruity was found to be mediated through time personality, thus contributing to the person–job (P–J) fit literature which suggests that direct effects are often more important than indirect effects. The study also provides some practical examples of ways to address some of the previously cited methodological issues in P–J fit research
An Overview of Fluctuation and Correlation Results in Relativistic Heavy Ion Collisions
A great deal of recent data on event-by-event fluctuation and correlation
measurements has been released by several experiments at the SPS and RHIC.
Recent results on charge fluctuations, balance functions in pseudorapidity, and
average transverse momentum fluctuations will be reviewed. The results will be
compared to various model predictions after examining contributions to each
observable from known physics processes.Comment: 8 pages, 3 figures. Contribution to the Proceedings of the 17th
International Conference on Ultra Relativistic Nucleus-Nucleus Collisions
(Quark Matter 2004), Oakland, California, 11-17 Jan 2004. Submitted to
J.Phys.
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