2,127 research outputs found
-dependence of backward pion multiplicity in neutrino-nucleus interactions
The production of pions emitted backward in inelastic neutrino-nucleus
interactions is analyzed within the impulse approximation in the framework of
the dual parton model. We focus on the -dependence of the multiplicity of
negative pions, normalized to the total cross section of the reaction . The inclusion of planar (one-Reggeon exchange) and cylindrical
(one-Pomeron exchange) graphs leads to a multiplicity that decreases as
increases, in agreement with recent measurements carried out at CERN by the
NOMAD collaboration. A realistic treatment of the high momentum tail of the
nucleon distribution in a nucleus also allows for a satisfactory description of
the semi-inclusive spectrum of backward pions.Comment: 15 pages, 4 figure
Hadron Multiplicity in Semi-Inclusive Lepton-Nucleon and Lepton-Nucleus Scattering
We discuss multi-hadron production in both inelastic neutrino-nucleon
interactions in the current fragmentation region and neutrino-nucleus
collisions in the target fragmentation region. Our analysis, carried out within
the framework of the quark-gluon string model, is mainly focused on the
difference between these two processes. We show that the dependence of
hadron multiplicity in the current and target fragmentation regions is indeed
completely different. The study of inelastic scattering in the target
fragmentation region also provides new information on nuclear structure at
small distances. The results of the proposed approach are in satisfactory
agreement with the data recently obtained at CERN by the NOMAD Collaboration.Comment: Talk delivered a the Fourth International Conference on Perspectives
in Hadronic Physics (ICTP, Trieste, Italy, May 2003). To be published in the
Proceedings (EPJA
On the re-summation of enhanced Pomeron diagrams
Dominant contributions of enhanced Pomeron diagrams to elastic hadron-hadron
scattering amplitude are re-summed to all orders. The formalism is applied to
calculate total hadronic cross sections and elastic scattering slopes. An
agreement with earlier results is obtained
Baryon stopping and hyperon enhancement in the improved dual parton model
We present an improved version of the dual parton model which contains a new
realization of the diquark breaking mechanism of baryon stopping. We reproduce
in this way the net baryon yield in nuclear collisions. The model, which also
considers strings originating from diquark-antidiquark pairs in the nucleon
sea, reproduces the observed yields of p and Lambda and their antiparticles and
underestimates cascades by less than 50 %. However, Omega's are underestimated
by a factor five. Agreement with data is restored by final state interaction,
with an averaged cross-section as small as 0.14 mb. Hyperon yields increase
significantly faster than antihyperons, in agreement with experiment.Comment: 40 pages, 18 postscript figure
Relative states, quantum axes and quantum references
We address the problem of measuring the relative angle between two "quantum
axes" made out of N1 and N2 spins. Closed forms of our fidelity-like figure of
merit are obtained for an arbitrary number of parallel spins. The asymptotic
regimes of large N1 and/or N2 are discussed in detail. The extension of the
concept "quantum axis" to more general situations is addressed. We give optimal
strategies when the first quantum axis is made out of parallel spins whereas
the second is a general state made out of two spins.Comment: 6 pages, no figure
Unexpected metal micro/nanoparticles in mediastinal lymph nodes: a combined µXRF and INAA case study
How coloniality shapes the making of Latin American psychologists: ethnographic evidence from Ecuador
This paper provides ethnographic evidence on how coloniality shapes the making of Latin American psychologists. A critical ethnography was conducted at a psychology training institution in Ecuador, consisting of twelve months of participant observation; forty-one semi-structured interviews; and analysis of academic discourse, photos, videos and relevant social media content. The research was guided by the tradition of Critical Psychology – specifically Liberation Psychology – and Critical Discourse Analysis. Findings suggest the pervasiveness of coloniality in the making of Ecuadorian psychologists and, hypothetically, of others in Latin America and the wider Global South. Interpretations also highlight the non-essentialist, non-dichotomist, ‘messy’ nature of such processes, a consideration which may advance current ethical and analytical debates on decolonisation. Echoing ongoing critical arguments, authors suggest that a ‘help-as-war’ metaphor is a category with potential value to contribute to such advancement, an approach that has important theoretical and pragmatic implications for researchers and practitioners
On asimuthal anisotropy in fragmentation of classical relativistic string
A fragmenting relativistic string is widely used for modelling particle
production via quark-gluon strings formed in hadron inelastic interactions of
high energies. In this note we focus on motion and fragmentation of
relativistic string with non-zero transverse separation of its ends and study
this scenario as a possible mechanism bringing anisotropy into the asimuthal
angle disribution of produced particles in inelastic interactions of hadrons.Comment: 12 pages, 6 figure
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