3,512 research outputs found
The weight of emotions in decision-making: how fearful and happy facial stimuli modulate action readiness of goal-directed actions
Modern theories of behavioral control converge with the idea that goal-directed/voluntary behaviors are intimately tied to the evaluation of resources. Of key relevance in the decision-making processes that underlie action selection are those stimuli that bear emotional content. However, even though it is acknowledged that emotional information affects behavioral control, the exact way in which emotions impact on action planning is largely unknown. To clarify this issue, I gave an emotional version of a go/no-go task to healthy participants, in which they had to perform the same arm reaching movement when pictures of fearful or happy faces were presented, and to withhold it when pictures of faces with neutral expressions were presented. This task allows for the investigation of the effects of emotional stimuli when they are task-relevant without conflating movement planning with target detection and task switching. It was found that both the reaction times (RTs) and the percentages of errors increased when the go-signal was the image of a fearful looking face, as opposed to when the go-signal was a happy looking face. Importantly, to control for the role of the features of the stimuli, I ran a control task in which the same pictures were shown; however, participants had to move/withhold the commanded movement according to gender, disregarding the emotional valence. In this context, the differences between RTs and error percentages between the fearful and happy faces disappeared. On the one hand, these results suggest that fearful facial stimuli are likely to capture and hold attention more strongly than faces that express happiness, which could serve to increase vigilance for detecting a potential threat in an observer's environment. On the other hand, they also suggest that the influence of fearful facial stimuli is not automatic, but it depends on the task requirements
External leg corrections in the unitarity method
Unitarity cuts diverge in the channel of a single massive external fermion.
We propose an off-shell continuation of the momentum that allows a finite
evaluation of the unitarity cuts. If the cut is taken with complete amplitudes
on each side, our continuation and expansion around the on-shell configuration
produces the finite contribution to the bubble coefficient. Finite parts in the
expansion of the external leg counterterms must be included explicitly as well.Comment: 28 pages, 9 figures. Published version. Eq. (B.17) corrected, minor
clarifications, typos fixe
Multiloop Integrand Reduction for Dimensionally Regulated Amplitudes
We present the integrand reduction via multivariate polynomial division as a
natural technique to encode the unitarity conditions of Feynman amplitudes. We
derive a recursive formula for the integrand reduction, valid for arbitrary
dimensionally regulated loop integrals with any number of loops and external
legs, which can be used to obtain the decomposition of any integrand
analytically with a finite number of algebraic operations. The general results
are illustrated by applications to two-loop Feynman diagrams in QED and QCD,
showing that the proposed reduction algorithm can also be seamlessly applied to
integrands with denominators appearing with arbitrary powers.Comment: Published version. 5 pages, 2 figure
Integrand Reduction for Two-Loop Scattering Amplitudes through Multivariate Polynomial Division
We describe the application of a novel approach for the reduction of
scattering amplitudes, based on multivariate polynomial division, which we have
recently presented. This technique yields the complete integrand decomposition
for arbitrary amplitudes, regardless of the number of loops. It allows for the
determination of the residue at any multiparticle cut, whose knowledge is a
mandatory prerequisite for applying the integrand-reduction procedure. By using
the division modulo Groebner basis, we can derive a simple integrand recurrence
relation that generates the multiparticle pole decomposition for integrands of
arbitrary multiloop amplitudes. We apply the new reduction algorithm to the
two-loop planar and nonplanar diagrams contributing to the five-point
scattering amplitudes in N=4 super Yang-Mills and N=8 supergravity in four
dimensions, whose numerator functions contain up to rank-two terms in the
integration momenta. We determine all polynomial residues parametrizing the
cuts of the corresponding topologies and subtopologies. We obtain the integral
basis for the decomposition of each diagram from the polynomial form of the
residues. Our approach is well suited for a seminumerical implementation, and
its general mathematical properties provide an effective algorithm for the
generalization of the integrand-reduction method to all orders in perturbation
theory.Comment: 32 pages, 4 figures. v2: published version, text improved, new
subsection 4.4 adde
NLO electroweak contributions to squark pair production at the LHC
We present the tree-level and next-to-leading order (NLO) electroweak (EW)
contributions to squark-squark production at the Large Hadron Collider (LHC)
within the framework of the Minimal Supersymmetric Standard Model (MSSM).Comment: To appear in the proceedings of 17th International Conference on
Supersymmetry and the Unification of Fundamental Interactions (SUSY09),
Boston, USA, 5-10 Jun 200
Electroweak corrections to squark-antisquark production at the LHC
We present the calculation of the electroweak corrections for
squark-antisquark pair production at the LHC within the Minimal Supersymmetric
Standard Model. Taking into account all possible chirality and light-flavor
configurations, we evaluate the NLO EW corrections, which are of O(a_s^2 a), as
well as the subleading tree-level contributions of O(a_s a) and O(a^2).
Numerical results are presented for several scans in the SUSY parameter space
and relevant differential distributions are investigated. The impact of the
electroweak corrections is nonnegligible and strongly depends on the chirality
configuration of the produced squarks. Our analysis includes a discussion of
photon-gluon initiated processes with a focus on the impact of the
corresponding large PDF uncertainties.Comment: 33 pages, 12 figures; V2: Original results unchanged. Various minor
modifications. Matches version published in JHE
Top-squark pair production at the LHC: a complete analysis at next-to-leading order
We present a complete next-to-leading order study of top-squark pair
production at the LHC, including QCD and EW corrections. The calculation is
performed within the Minimal Supersymmetric Standard Model and numerical
results are presented for parameter regions compatible with the observed Higgs
boson. We employ the most recent parton distribution functions including QED
corrections and we find NLO EW corrections to the inclusive stop-pair
production cross section up to compared to the leading-order
prediction. Besides corrections to inclusive cross sections also important
kinematic distributions are investigated.Comment: 27 pages, 10 figures. Version published in JHEP. The numerical
discussion in Section 3 has been extended. References have been adde
Beyond Reactive Inhibition: Unpacking the Multifaceted Nature of Motor Inhibition
Editorial on the Special Issue "How Does Motor Inhibitory Control Emerge from the Interplay between Reactive and Proactive Inhibition
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