2,945 research outputs found
Proton structure, an iridescent study: from parton distributions to the emergence of the proton mass
No full textThe twist-three distribution eq(x,k⊥) in a light-front model
No full textWe discuss the twist-three, unpolarized, chiral-odd, transverse momentum dependent parton distribution (TMD) eq(x,k⊥) within a light-front model. We review a model-independent decomposition of this TMD, which follows from the QCD equations of motion and is given in terms of a mass term, a pure interaction-dependent contribution, and singular terms. The mass-term and pure twist-three contributions are represented in terms of overlap of light-front wave functions (LFWFs), taking into account the Fock states with three valence quark (3q) and three-quark plus one gluon (3q+g). The 3q and 3q+g LFWFs with total orbital angular momentum zero are modeled using a parametrization derived from the conformal expansion of the proton distribution amplitudes, with parameters fitted to reproduce available phenomenological information on the unpolarized leading-twist quark and gluon collinear parton distributions. Numerical predictions for both the quark TMD eq(x,k⊥) and the collinear parton distribution eq(x) are presented, discussing the role of the quark–gluon correlations in the proton. Keywords: Higher-twist transverse momentum dependent parton distributions, Quark–gluon correlations, Light-front wave function
Quark-gluon correlations in the twist-3 TMD using light-front wave functions
No full textWe discuss a T-even, twist-3 transverse momentum dependent parton distribution for unpolarized proton. We review its general, model-independent and gauge-independent decomposition, which follows from the QCD equations of motion and it is given in terms of a lower-twist distribution, a pure twist-3 distribution and singular terms. Then we present the results for the twist-3 distribution, using a Light-Front Wave Function (LFWF) overlap representation and taking into account the contribution from the three-quark and the three-quark plus a gluon proton’s Fock-states. Predictions are obtained using a model for the LFWFs, based on the conformal expansion of the proton distribution amplitudes. The parameters of the LFWFs are fixed to reproduce phenomenological parametrizations of the collinear twist-2 unpolarized parton distribution
Supplemental_materials - A Lack of Practice Effects on Memory Tasks Predicts Conversion to Alzheimer Disease in Patients With Amnestic Mild Cognitive Impairment
No full textSupplemental_materials for A Lack of Practice Effects on Memory Tasks Predicts Conversion to Alzheimer Disease in Patients With Amnestic Mild Cognitive Impairment by Maria Stefania De Simone, Roberta Perri, Marta Rodini, Lucia Fadda, Massimo De Tollis, Carlo Caltagirone and Giovanni Augusto Carlesimo in Journal of Geriatric Psychiatry and Neurology</p
Rozpor ako východisko, láska ako smer u Simone Weilovej (Contradiction as base, Love as direction in writings of Simone Weil)
No full textArticle is explaining contradiction and love, Simone Weil‘s essential terms of hermeneutics of human Being. It introduces close relation of these terms with her understanding of God as well as with her overall concept of religion. Author also mentions Simone Weil‘s inspirations with philosophical and spiritual concepts of the East
The valence quark, sea, and gluon content of the pion from the parton distribution functions and the electromagnetic form factor
No full textWe present a light-front model calculation of the pion parton distribution
functions (PDFs) and the pion electromagnetic form factor. The pion state is
modeled in terms of light-front wave functions (LFWFs) for the ,
, , and components. We design the
LFWFs so that the parameters in the longitudinal and transverse momentum space
enter separately in the fit of the pion PDFs and the electromagnetic form
factor, respectively. We extract the pion PDFs within the xFitter framework
using available Drell-Yan and photon-production data. With the obtained
parameters in the longitudinal-momentum space, we then fit the available
experimental data on the pion electromagnetic form factor to constrain the
remaining parameters in the transverse-momentum space. The results for the pion
PDFs are compatible with existing extractions and lattice calculations, and the
fit to the pion electromagnetic form factor data works quite successfully. The
obtained parametrization for the LFWFs marks a step forward towards a unified
description of different hadron distribution functions in both the
longitudinal- and transverse-momentum space and will be further applied to a
phenomenological study of transverse-momentum dependent parton distribution
functions and generalized parton distributions.Comment: 18 pages, 3 figures; typos corrected, one reference added and
discussion of the model extended; version to appear in Phys. Rev.
Accelerated long-term forgetting in neurodegenerative disorders: A systematic review of the literature
No full textAccelerated Long-term Forgetting (ALF) is a memory deficit characterised by normal retention up to relatively short intervals (e.g., minutes, hours) with increased forgetting over longer periods (e.g., days, weeks). ALF is often underestimated due to a lack of common memory assessments beyond 30-60 min. The purpose of this review was to provide an overview of ALF occurrence in neurodegenerative disorders, evaluating whether it can be considered a cognitive deficit useful for diagnosing and monitoring patients. We included 19 experimental studies that investigated ALF in neurodegenerative disorders. Most papers were focused on Alzheimer's disease (AD) dementia and related forms of cognitive decline (Mild Cognitive Impairment, Subjective Cognitive decline, Pre-symptomatic subjects at risk of AD dementia). The major finding of the present work concerns the presence of ALF in very early forms of cognitive decline related to AD. These findings, supporting the hypothesis that ALF is a subtle and undetected hallmark of pre-clinical AD, highlights the importance of investigating forgetting over a longer period and devising standardised measures to be included in clinical practice
“I beg you to tell me what has become of Djamila”: The Political Mobilization of Simone de Beauvoir’s Readers During the Boupacha Affair
No full textBy Sophia Millman This is a condensed version of a Masters thesis dedicated to the political mobilization of Simone de Beauvoir’s readers. The citations from the letters were translated from French by the author. *** On June 2, 1960, the French government ordered all copies of the daily Algiers edition of Le Monde seized and destroyed to suppress the publication of Simone de Beauvoir’s article “Pour Djamila Boupacha.” Beauvoir, a self-professed “woman of letters”, not “of action[1]”, and one ..
Exploring mechanisms that affect retrograde memory for public events in amnestic mild cognitive impairment: A longitudinal update
No full text: Here, we examined mechanisms that affect retrograde memory in amnestic mild cognitive impairment (a-MCI) as a function of longitudinal clinical outcome. 8 a-MCI who converted to Alzheimer's dementia (AD) during the subsequent 3-year follow-up (converter a-MCI) and 10 a-MCI who remained clinically stable during the same period (stable a-MCI) were compared at the baseline evaluation (i.e., when they were diagnosed as a-MCI) using a remote memory questionnaire for public events that allows disentangling the differential contribution of storage and retrieval mechanisms to performance accuracy. Results suggest that deficits in remote memory are primarily explained by impaired retrieval abilities in stable a-MCI and by impaired storage in converter-to-AD a-MCI. This distinction between retrograde amnesia due to defective trace utilisation in stable a-MCI and trace storage in converter a-MCI is consistent with the temporal unfolding of declining anterograde memory over the course of disease progression to AD
Lensing function relation in Hadrons
No full textWe discuss the origin of nontrivial relations between transverse distortions in the distribution of quarks in impact-parameter space and analogous distortions in transverse-momentum space due T-odd effects. We show that these relations can be established under very specific conditions, typically realized only in models that describe hadrons as two-body bound systems and involving a helicity-conserving coupling between the gauge boson and the spectator system
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