110 research outputs found
Simple superamplitudes in higher dimensions
We provide simple superspaces based on a formulation of spinor helicity in
general even dimensions. As a distinguishing feature these spaces admit a
fermionic super-momentum conserving delta function solution to the on-shell
supersymmetry Ward identities. Using these solutions, we present beautifully
simple formulae for the complete three, four and five point superamplitudes in
maximal super Yang-Mills theory in eight dimensions, and for the three and four
point superamplitudes in ten dimensional type IIB supergravity. In addition, we
discuss the exceptional kinematics of the three point amplitude, and the
supersymmetric spinorial BCFW recursion, in general dimensions.Comment: 34 page
The one-loop six-dimensional hexagon integral and its relation to MHV amplitudes in N=4 SYM
We provide an analytic formula for the (rescaled) one-loop scalar hexagon
integral with all external legs massless, in terms of classical
polylogarithms. We show that this integral is closely connected to two
integrals appearing in one- and two-loop amplitudes in planar
super-Yang-Mills theory, and . The derivative of
with respect to one of the conformal invariants yields
, while another first-order differential operator applied to
yields . We also introduce some kinematic
variables that rationalize the arguments of the polylogarithms, making it easy
to verify the latter differential equation. We also give a further example of a
six-dimensional integral relevant for amplitudes in
super-Yang-Mills.Comment: 18 pages, 2 figure
Yangian symmetry of light-like Wilson loops
We show that a certain class of light-like Wilson loops exhibits a Yangian
symmetry at one loop, or equivalently, in an Abelian theory. The Wilson loops
we discuss are equivalent to one-loop MHV amplitudes in N=4 super Yang-Mills
theory in a certain kinematical regime. The fact that we find a Yangian
symmetry constraining their functional form can be thought of as the effect of
the original conformal symmetry associated to the scattering amplitudes in the
N=4 theory.Comment: 15 pages, 5 figure
Three particle superstring amplitudes with massive legs
On-shell superspaces and associated spinor helicity techniques give an
efficient formulation of the Ward identities of on-shell supersymmetry for
scattering amplitudes and supply tools to construct their solutions. Based on
these techniques in this paper the general solutions of the Ward identities are
presented for three particle scattering amplitudes with one, two or three
massive legs for simple supersymmetry in ten and eight dimensions. It is shown
in examples how these solutions may be used to obtain concrete amplitudes for
the closed (IIB) and open superstring in a flat background. Explicit results
include all three point amplitudes with one massive leg whose functional form
is shown to be dictated completely by super-Poincare symmetry. The resulting
surprisingly simple series only involves massive superfields labelled by
completely symmetric little group representations. The extension to more
general explicit three and higher point amplitudes in string theory is
initiated. In appendices the field content of the fundamental massive
superfields of the open and closed superstring are listed in terms of the
Dynkin labels of a variety of groups which may be of independent interest.Comment: 45 pages. v2: typos corrected, references adde
Willing suspension of disbelief: a study in online learning through simulation, and its potential for deeper learning in Higher Education
This article describes the replacement of a 'traditionally taught' law of probate course (lectures and workshops/tutorials) with an on-line collaborative learning exercise using simulation and role-play which is referred to hereafter as the Transactional Learning Project ('TLP'). The article considers the theory that the emotional engagement that comes about through role play in simulation leads to deeper learning, a process Maharg (2010) has dubbed as the 'integration of the cognitive and the affective'. The article includes statistical analysis of student feedback on the TLP in an attempt to measure how easy it is to carry students predisposed to expect information to be 'given' rather than 'acquired' along the journey leading away from traditional didactic teaching. The project was motivated partly by the dearth of such learning practices on the Legal Practice Course. It is suggested that the findings of the project add to the body of research which tends to illustrate the success in terms of student learning from working in leaderless (i.e. where the tutor is absent from the collaborative group) groups engaged in practical tasks involving simulation
Amplitudes for Multiple M5 Branes
We study N=(m,0) super-Poincare invariant six-dimensional massless and
five-dimensional massive on-shell amplitudes. We demonstrate that in six
dimensions, all possible three-point amplitudes involving tensor multiplets are
necessarily embedded in gravitational theories. For non-gravitational
amplitudes we consider instead five-dimensional massive amplitudes with N=(2,0)
supersymmetry, aiming at describing the world volume theory of multiple M5
branes compactified on M^{4,1}x S^1. We find non-gravitational amplitudes whose
on-shell degrees of freedom are shown to match those of the massive particle
states that arise from self-dual strings wrapping a circle. Along the way we
find interesting hints of a fermionic symmetry in the (2,0) theory, which
accompanies the self-dual tensor gauge symmetry. We also discuss novel theories
with (3,0) and (4,0) supersymmetry.Comment: 49 pages, 4 figures, v2: Better organization and more details in the
section on KK interaction
Cultivating reflexive research practice when using participants’ photographs as research data
This chapter reflects on a study exploring the development of a feminist consciousness. During the interviews participants were invited to share photographs that were significant to their feminist becoming. Various ethical and methodological challenges arose through the use of visual data, in particular the ethics of the interpretation and dissemination of participants’ personal photographs. Both issues were highlighted and addressed through reflexive research practice, which exposed how the researcher’s reaction to and feelings about the photographs impacted upon how they were interpreted and shared. Reflexivity demands that researchers interrogate their research choices and is essential for ethical and rigorous research. This chapter argues that visual methods, whilst posing new ethical challenges, can enhance the reflexive research practice necessary for responding to and navigating its challenges
Bootstrapping the three-loop hexagon
We consider the hexagonal Wilson loop dual to the six-point MHV amplitude in
planar N=4 super Yang-Mills theory. We apply constraints from the operator
product expansion in the near-collinear limit to the symbol of the remainder
function at three loops. Using these constraints, and assuming a natural ansatz
for the symbol's entries, we determine the symbol up to just two undetermined
constants. In the multi-Regge limit, both constants drop out from the symbol,
enabling us to make a non-trivial confirmation of the BFKL prediction for the
leading-log approximation. This result provides a strong consistency check of
both our ansatz for the symbol and the duality between Wilson loops and MHV
amplitudes. Furthermore, we predict the form of the full three-loop remainder
function in the multi-Regge limit, beyond the leading-log approximation, up to
a few constants representing terms not detected by the symbol. Our results
confirm an all-loop prediction for the real part of the remainder function in
multi-Regge 3-->3 scattering. In the multi-Regge limit, our result for the
remainder function can be expressed entirely in terms of classical
polylogarithms. For generic six-point kinematics other functions are required.Comment: 36 pages, 1 figure, plus 8 ancillary files containing symbols of
functions; v2 minor typo correction
Unfitting, uncomfortable, unacademic: a sociological reading of an interactive mobile phone app in university lectures
Abstract Scholarly literature on education technology uptake has been dominated by technological determinist readings of students’ technology use. However, in recent years there has been a move by sociologists of education to highlight how the contexts in which educational technologies are introduced are not tabula rasa but socially and culturally complex. This study approaches technology as a social construct, arguing that students construct discursive meaning of, rather than simply respond to, technologies for learning. The study explores students’ constructions of a mobile learning app that was introduced into lectures during a year-long university course. Students largely rejected the app, constructing it as unfitting for the context, a socially uncomfortable experience and an unacademic way of learning. The paper highlights the limitations of technological determinism and closes by arguing for readings of educational technologies that pay close attention to students’ voices
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