6,128 research outputs found
Estimate of the Collins function in a chiral invariant approach
We estimate the Collins function at a low energy scale by calculating the
fragmentation of a quark into a pion at the one-loop level in the chiral
invariant model of Manohar and Georgi. We give a useful parametrization of our
results and we briefly discuss different spin and/or azimuthal asymmetries
containing the Collins function and measurable in semi-inclusive DIS and e+ e-
annihilationComment: 5 pages, 4 figures, to appear in Proceedings of 10th International
Workshop on Deep Inelastic Scattering (DIS 2002), Cracow, Poland, 30 Apr-4
May 200
Emotional crisis in a naturalistic context: characterizing outpatient profiles and treatment effectiveness.
Crisis happens daily yet its understanding is often limited, even in the field of psychiatry. Indeed, a challenge is to assess the potential for change of patients so as to offer appropriate therapeutic interventions and enhance treatment program efficacy. This naturalistic study aimed to identify the socio-demographical characteristics and clinical profiles at admission of patients referred to a specialized Crisis Intervention Center (CIC) and to examine the effectiveness of the intervention.
The sample was composed of 352 adult outpatients recruited among the referrals to the CIC. Assessment completed at admission and at discharge examined psychiatric symptoms, defense mechanisms, recovery styles and global functioning. The crisis intervention consisted in a psychodynamically oriented multimodal approach associated with medication.
Regarding the clinical profiles at intake, patients were middle-aged (M = 38.56, SD = 10.91), with a higher proportion of women (62.22%). They were addressed to the CIC because they had attempted to commit suicide or had suicidal ideation or presented depressed mood related to interpersonal difficulties. No statistical differences were found between patients dropping out (n = 215) and those attending the crisis intervention (n = 137). Crisis intervention demonstrated a beneficial effect (p < 0.01) on almost all variables, with Effect Sizes (ES) ranging from small to large (0.12 < ES < 0.75; median = 0.49). However, the Reliable Change Index indicated that most of the issues fall into the undetermined category (range 41.46 to 96.35%; median = 66.20%).
This study establishes the profile of patients referred to the CIC and shows that more than half of the patients dropped out from the crisis intervention before completion. Our findings suggest that people presenting an emotional crisis benefit from crisis intervention. However, given methodological constraints, these results need to be considered with caution. Moreover, the clinical significance of the improvements is not confirmed. Thus, the effectiveness of crisis intervention in naturalistic context is not fully determined and should be more rigorously studied in future research
Estimate of the Collins fragmentation function in a chiral invariant approach
We predict the features of the Collins function, which describes the
fragmentation of a transversely polarized quark into an unpolarized hadron, by
modeling the fragmentation process at a low energy scale. We use the chiral
invariant approach of Manohar and Georgi, where constituent quarks and
Goldstone bosons are considered as effective degrees of freedom in the
non-perturbative regime of QCD. To test the approach we calculate the
unpolarized fragmentation function and the transverse momentum distribution of
a produced hadron, both of which are described reasonably well. In the case of
semi-inclusive deep-inelastic scattering, our estimate of the Collins function
in connection with the transversity distribution gives rise to a transverse
single spin asymmetry of the order of 10%, supporting the idea of measuring the
transversity distribution of the nucleon in this way. In the case of e+ e-
annihilation into two hadrons, our model predicts a Collins azimuthal asymmetry
of about 5%.Comment: 12 pages, 15 figures. Figs. 11-14 changed, minor changes in
discussion, few typos fixed and some references added. Final version to
appear in PR
What can break the Wandzura--Wilczek relation?
We analyze the breaking of the Wandzura-Wilczek relation for the g_2
structure function, emphasizing its connection with transverse momentum
dependent parton distribution functions. We find that the relation is broken by
two distinct twist-3 terms, and clarify how these can be separated in
measurements of double-spin asymmetries in semi-inclusive deep inelastic
scattering. Through a quantitative analysis of available g_2 data we also show
that the breaking of the Wandzura-Wilczek relation can be as large as 15-30% of
the size of g_2.Comment: 12 page
Semi-inclusive vector meson production in DIS
We analyze one-particle inclusive DIS in the case when a spin-1 hadron (such
as a vector meson) is observed in the final state. We consider only leading
order contributions in 1/Q, but we include transverse momentum of partons.
Several new fragmentation functions appear in cross sections. One of them can
be measured in connection with the transverse-spin disbtribution function h_1.Comment: 3 pages, uses sprocl.sty, talk given at the DIS2000 conference,
Liverpool, England, April 2000, to appear in the conference proceeding
Gauge links for transverse momentum dependent correlators at tree-level
In this paper we discuss the incorporation of gauge links in hadronic matrix
elements that describe the soft hadronic physics in high energy scattering
processes. In this description the matrix elements appear in soft correlators
and they contain non-local combinations of quark and gluon fields. In our
description we go beyond the collinear approach in which case also the
dependence on transverse momenta of partons is taken into consideration. The
non-locality in the transverse direction leads to a complex gauge link
structure for the full process, in which color is entangled, even at
tree-level. We show that at tree-level in a 1-parton unintegrated (1PU)
situation, in which only the transverse momentum of one of the initial state
hadrons is relevant, one can get a factorized expression involving transverse
momentum dependent (TMD) distribution functions. We point out problems at the
level of two initial state hadrons, even for relatively simple processes such
as Drell-Yan scattering.Comment: 25 pages, corrected typos and updated reference
Novedades floristicas para el n de Marruecos
Se han seleccionado 29 novedades comarcales para el Catálogo de la flora del N de Marruecos, entre las especies recolectadas para el programa Semclimed en el país magrebí, durante la segunda parte de la campaña del mes de mayo de 2007. Estas campañas estaban orientadas a la recolección de semillas y la localización de poblaciones de especies raras y endémicas para el nuevo banco de germoplasma del Institut ScientiK que de la Universidad Mohamed V de Rabat, SEMCLIMED (Interreg IIIB Medocc-2005-05-4.1-E-110. Los recientes trabajos realizados en la catalogación de la flora del N de Marruecos permiten, a su vez, valorar el interés corológico de estas recolecciones
A Decolonial Critique of the Racialized “Localwashing” of Extraction in Central Africa
Responding to calls for increased attention to actions and reactions “from above” within the
extractive industry, we offer a decolonial critique of the ways in which corporate entities and multinational institutions propagate racialized rhetoric of “local” suffering, “local” consultation, and “local” fault for failure in extractive zones. Such rhetoric functions to legitimize extractive intervention within a set of practices that we call localwashing. Drawing from a decade of research on and along the Chad-Cameroon Oil Pipeline, we show how multi-scalar actors converged to assert knowledge of, responsibility for, and collaborations with “local” people within a racialized politics of scale. These corporate representations of the racialized “local” are coded through long-standing colonial tropes. We identify three interrelated and overlapping flexian elite rhetoric(s) and practices of racialized localwashing: (a) anguishing, (b) arrogating, and (c) admonishing. These elite representations of a racialized “local” reveal diversionary efforts “from above” to manage public opinion, displace blame for project failures, and domesticate dissent in a context of persistent scrutiny and criticism from international and regional advocates and activists
Bounds on transverse momentum dependent distribution and fragmentation functions
We give bounds on the distribution and fragmentation functions that appear at
leading order in deep inelastic 1-particle inclusive leptoproduction or in
Drell-Yan processes. These bounds simply follow from positivity of the defining
matrix elements and are an important guidance in estimating the magnitude of
the azimuthal and spin asymmetries in these processes.Comment: 5 pages, Revtex, 3 Postscript figures, version with minor changes, to
be published in Physical Review Letter
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