2,970 research outputs found
Cosmological Implications of the Tetron Model of Elementary Particles
Based on a possible solution to the tetron spin problem, a modification of
the standard Big Bang scenario is suggested, where the advent of a spacetime
manifold is connected to the appearance of tetronic bound states. The metric
tensor is constructed from tetron constituents and the reason for cosmic
inflation is elucidated. Furthermore, there are natural dark matter candidates
in the tetron model. The ratio of ordinary to dark matter in the universe is
calculated to be 1:5.Comment: 23 page
Polarized deep inelastic scattering at high energies and parity violating structure functions
A comprehensive analysis of deep inelastic scattering of polarized charged
leptons on polarized nucleons is presented; weak interaction contributions,
both in neutral and charged current processes, are taken into account and the
parity violating polarized nucleon structure functions are studied. Possible
ways of their measurements and their interpretations in the parton model are
discussed.Comment: (slightly modified version, includes a few new references and
corrects few misprints for publication), 14 pages in TeX (needs harvmac) no
figure, DFTT 80/9
Effect of polarized gluon distribution on spin asymmetries for neutral and charged pion production
A longitudinal double spin asymmetry for \pi^0 production has been measured
by the PHENIX collaboration. The asymmetry is sensitive to the polarized gluon
distribution and is indicated to be positive by theoretical predictions. We
study a correlation between behavior of the asymmetry and polarized gluon
distribution in neutral and charged pion production at RHIC.Comment: 7 pages, 5 eps figures, section added, typos corrected. to be
published in PR
On ‘Organized Crime’ in the illicit antiquities trade: moving beyond the definitional debate
The extent to which ‘organized crime’ is involved in illicit antiquities trafficking is unknown and frequently debated. This paper explores the significance and scale of the illicit antiquities trade as a unique transnational criminal phenomenon that is often said to be perpetrated by and exhibit traits of so-called ‘organized crime.’ The definitional debate behind the term ‘organized crime’ is considered as a potential problem impeding our understanding of its existence or extent in illicit antiquities trafficking, and a basic progression-based model is then suggested as a new tool to move beyond the definitional debate for future research that may help to elucidate the actors, processes and criminal dynamics taking place within the illicit antiquities trade from source to market. The paper concludes that researchers should focus not on the question of whether organized criminals- particularly in a traditionally conceived, mafia-type stereotypical sense- are involved in the illicit antiquities trade, but instead on the structure and progression of antiquities trafficking itself that embody both organized and criminal dynamics
Precise determination of the Wtb couplings at LHC
Top pair production at LHC is the ideal place to search for nonstandard Wtb
couplings in t -> W b -> l nu b decays. The lb forward-backward asymmetry in
the W rest frame is very sensitive to sigma_{mu nu} couplings, and can spot
one-loop QCD corrections to the decay vertex with more than 5 sigma statistical
significance. We discuss the potential of this asymmetry to signal nonstandard
gamma_mu and sigma_{mu nu} couplings and compare with top-antitop spin
correlation asymmetries, which have a lower sensitivity. We also briefly
summarise the results for Tevatron.Comment: LaTeX, 12 pages, 2 PS figures. One reference added. To be published
in PR
One-loop N-point equivalence among negative-dimensional, Mellin-Barnes and Feynman parametrization approaches to Feynman integrals
We show that at one-loop order, negative-dimensional, Mellin-Barnes' (MB) and
Feynman parametrization (FP) approaches to Feynman loop integrals calculations
are equivalent. Starting with a generating functional, for two and then for
-point scalar integrals we show how to reobtain MB results, using
negative-dimensional and FP techniques. The point result is valid for
different masses, arbitrary exponents of propagators and dimension.Comment: 11 pages, LaTeX. To be published in J.Phys.
"It All Ended in an Unsporting Way": Serbian Football and the Disintegration of Yugoslavia, 1989-2006
Part of a wider examination into football during the collapse of Eastern European Communism between 1989 and 1991, this article studies the interplay between Serbian football and politics during the period of Yugoslavia's demise. Research utilizing interviews with individuals directly involved in the Serbian game, in conjunction with contemporary Yugoslav media sources, indicates that football played an important proactive role in the revival of Serbian nationalism. At the same time the Yugoslav conflict, twinned with a complex transition to a market economy, had disastrous consequences for football throughout the territories of the former Yugoslavia. In the years following the hostilities the Serbian game has suffered decline, major financial hardship and continuing terrace violence, resulting in widespread nostalgia for the pre-conflict era
Cluster structures on quantum coordinate rings
We show that the quantum coordinate ring of the unipotent subgroup N(w) of a
symmetric Kac-Moody group G associated with a Weyl group element w has the
structure of a quantum cluster algebra. This quantum cluster structure arises
naturally from a subcategory C_w of the module category of the corresponding
preprojective algebra. An important ingredient of the proof is a system of
quantum determinantal identities which can be viewed as a q-analogue of a
T-system. In case G is a simple algebraic group of type A, D, E, we deduce from
these results that the quantum coordinate ring of an open cell of a partial
flag variety attached to G also has a cluster structure.Comment: v2: minor corrections. v3: references updated, final version to
appear in Selecta Mathematic
Scheme and Scale Dependence of Charm Production in Neutrino Scattering
We discuss some theoretical uncertainties in the calculation of the cross
section for charm production in charged current deep inelastic neutrino
scattering related to ambiguities in the treatment of terms which are singular
in the limit of a vanishing charm mass. In particular we compare the so-called
variable flavour scheme where these terms are absorbed in the parton
distribution functions containing the charm as an active flavour, with the
so-called fixed flavour scheme with no charm mass subtraction where the charm
appears only in the final state of fixed-order scattering matrix elements.
Using available parametrizations of parton distribution functions we find that
the two schemes lead to largely differing results for separate structure
functions whereas the differences cancel to a large extent in the total cross
section in that kinematical region which has been measured so far.Comment: 20pages, uuencoded postscript, figures include
Double logarithms, , and the NLO DGLAP evolution for the non-singlet component of the nucleon spin structure function,
Theoretical predictions show that at low values of Bjorken the spin
structure function, is influenced by large logarithmic corrections,
, which may be predominant in this region. These corrections are
also partially contained in the NLO part of the standard DGLAP evolution. Here
we calculate the non-singlet component of the nucleon structure function,
, and its first moment, using a unified evolution
equation. This equation incorporates the terms describing the NLO DGLAP
evolution and the terms contributing to the resummation. In order
to avoid double counting in the overlapping regions of the phase-space, a
unique way of including the NLO terms into the unified evolution equation is
proposed. The scheme-independent results obtained from this unified evolution
are compared to the NLO fit to experimental data, GRSV'2000. Analysis of the
first moments of shows that the unified evolution including the
resummation goes beyond the NLO DGLAP analysis. Corrections
generated by double logarithms at low influence the -dependence of the
first moments strongly.Comment: 13 pages, latex, 2 figures; Appendix adde
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