338 research outputs found
Holographic Technidilaton and LHC searches
We analyze in detail the phenomenology of a model of dynamical electroweak
symmetry breaking inspired by walking technicolor, by using the techniques of
the bottom-up approach to holography. The model admits a light composite scalar
state, the dilaton, in the spectrum. We focus on regions of parameter space for
which the mass of such dilaton is 125 GeV, and for which the bounds on the
precision electroweak parameter S are satisfied. This requires that the
next-to-lightest composite state is the techni-rho meson, with a mass larger
than 2.3 TeV. We compute the couplings controlling the decay rates of the
dilaton to two photons and to two (real or virtual) Z and W bosons. For generic
choices of the parameters, we find a suppression of the decay into heavy gauge
bosons, in respect to the analog decay of the standard-model Higgs. We find a
dramatic effect on the decay into photons, which can be both strongly
suppressed or strongly enhanced, the latter case corresponding to the large-N
regime of the dual theory. There is a correlation between this decay rate of
the dilaton into photons and the mass splitting between the techni-rho meson
and its axial-vector partner: if the decay is enhanced in respect to the
standard-model case, then the heavy spin-1 resonances are nearly degenerate in
mass, otherwise their separation in mass is comparable to the mass scale
itself.Comment: Very minor typos corrected. References adde
Solving the Coulomb scattering problem using the complex scaling method
Based on the work of Nuttall and Cohen [Phys. Rev. {\bf 188} (1969) 1542] and
Resigno et al{} [Phys. Rev. A {\bf 55} (1997) 4253] we present a rigorous
formalism for solving the scattering problem for long-range interactions
without using exact asymptotic boundary conditions. The long-range interaction
may contain both Coulomb and short-range potentials. The exterior complex
scaling method, applied to a specially constructed inhomogeneous Schr\"odinger
equation, transforms the scattering problem into a boundary problem with zero
boundary conditions. The local and integral representations for the scattering
amplitudes have been derived. The formalism is illustrated with numerical
examples.Comment: 3 pages, 3 figure
Development and validation of the student attitudes and beliefs about authorship scale: a psychometrically robust measure of authorial identity
One approach to plagiarism prevention focuses on improving students’ authorial identity, but work in this area depends on robust measures. This paper presents the development of a psychometrically robust measure of authorial identity - the Student Attitudes and Beliefs about Authorship Scale. In the item generation phase, a pool of items was developed and assessed for content validity by subject matter experts. In the exploratory phase, data from 439 higher education students were used to identify a latent variable model with three factors: ‘authorial confidence’, ‘valuing writing’ and ‘identification with author’. In the confirmatory phase, data from 306 higher education students were used to test the three-factor model's reliability and validity. The three-factor structure was confirmed, and the results showed the SABAS has a stronger psychometric basis than previously available measures. This measure of authorial identity can be used with confidence in research and pedagogy to help students improve their authorial identity
Non-supersymmetric Conifold
We find a new family of non-supersymmetric numerical solutions of IIB
supergravity which are dual to the N=1 cascading "conifold" theory perturbed by
certain combinations of relevant single trace and marginal double trace
operators with non infinitesimal couplings. The SUSY is broken but the
resulting ground states, and their gravity duals, remain stable, at least
perturbatively.Despite the complicated field theory dynamics the gravity
solutions have a simple structure. They feature the Ricci-flat non-Kahler
metric on the deformed conifold and the imaginary self-dual three-form flux
accompanied by a constant dilaton.Comment: 27 pages, 6 figures; v2: minor corrections; v3: comments adde
The effect of transmucosal 0.2mg/kg Midazolam premedication on dental anxiety, anaesthetic induction and psychological morbidity in children undergoing general anaesthesia for tooth extraction
<b>Background:</b> The project aims were to evaluate the benefit of transmucosal Midazolam 0.2mg/kg pre-medication on anxiety, induction behaviour and psychological morbidity in children undergoing general anaesthesia (GA) extractions. <b>Method:</b> 179 children aged 5-10 years (mean 6.53 years) participated in this randomised, double blind, placebo controlled trial. Ninety children had Midazolam placed in the buccal pouch. Dental anxiety was recorded pre operatively and 48 hours later using a child reported MCDAS-FIS scale. Behaviour at anaesthetic induction was recorded and psychological morbidity was scored by the parent using the Rutter Scale pre-operatively and again one-week later. Subsequent dental attendance was recorded at one, three and six months after GA. <b>Results:</b> Whilst levels of mental anxiety did not reduce overall, the most anxious patients demonstrated a reduction in anxiety after receiving midazolam premedicationmay (p=0.01). Neither induction behaviour nor psychological morbidity improved. Irrespective of group, parents reported less hyperactive (p= 0.002) and more prosocial behaviour (p=0.002) after the procedure:;, older children improved most (p=0.048), Post GA Dental attendance was poor and unrelated to after the procedure and unaffected by premedication. <b>Conclusion:</b> 0.2mg/kg buccal Midazolam provided some evidence for reducing anxiety in the most dentally anxious patients. However, induction behaviour, psychological morbidity and subsequent dental attendance were not found to alter between the premedication groups
Towards multi-scale dynamics on the baryonic branch of Klebanov-Strassler
We construct explicitly a new class of backgrounds in type-IIB supergravity
which generalize the baryonic branch of Klebanov-Strassler. We apply a
solution-generating technique that, starting from a large class of solutions of
the wrapped-D5 system, yields the new solutions, and then proceed to study in
detail their properties, both in the IR and in the UV. We propose a simple
intuitive field theory interpretation of the rotation procedure and of the
meaning of our new solutions within the Papadopoulos-Tseytlin ansatz, in
particular in relation to the duality cascade in the Klebanov-Strassler
solution. The presence in the field theory of different VEVs for operators of
dimensions 2, 3 and 6 suggests that this is an important step towards the
construction of the string dual of a genuinely multi-scale (strongly coupled)
dynamical model.Comment: 37 pages, 7 figures. References added, version to appear in JHE
The Holographic Dual of 2+1 Dimensional QFTs with N=1 SUSY and Massive Fundamental Flavours
The Maldacena Nastase solution is generalised to include massive fundamental
matter through the addition of a flavour profile. This gives a holographic dual
to N=1 SYM-CS with massive fundamental matter with a singularity free IR. We
study this solution in some detail confirming confinement and asymptotic
freedom. A recently proposed solution generating technique is then applied
which results in a new type-IIA supergravity solution. In a certain limit the
geometry of this solution is asymptotically AdS_4X Y, where Y is the metric at
the base of the Bryant-Salamon G_2 cone, which has topology S^3XS^3.Comment: 31 pages plus appendices, 6 figures. v3: Typos corrected, version to
appear in JHE
The Structure of the Non-SUSY Baryonic Branch of Klebanov-Strassler
We study the two-dimensional space of supergravity solutions corresponding to
non-supersymmetric deformations of the baryonic branch of Klebanov-Strassler.
By combining analytical methods with a numerical survey of the parameter space,
we find that this solution space includes as limits the softly-broken N=1
solutions of Gubser et al. and those of Dymarsky and Kuperstein. We also
identify a one-dimensional family of solutions corresponding to a natural
non-supersymmetric generalisation of Klebanov-Strassler, and one corresponding
to the limit in which supersymmetry is completely absent, even in the far UV.
For almost all of the parameter space we find indications that much of the
structure of the supersymmetric baryonic branch survives.Comment: 29 pages plus appendices, 11 figure
D3-D7 Quark-Gluon Plasmas at Finite Baryon Density
We present the string dual to SU(Nc) N=4 SYM, coupled to Nf massless
fundamental flavors, at finite temperature and baryon density. The solution is
determined by two dimensionless parameters, both depending on the 't Hooft
coupling at the scale set by the temperature T:
, weighting the backreaction of the flavor
fields and , where is the
baryon density. For small values of these two parameters the solution is given
analytically up to second order. We study the thermodynamics of the system in
the canonical and grand-canonical ensembles. We then analyze the energy loss of
partons moving through the plasma, computing the jet quenching parameter and
studying its dependence on the baryon density. Finally, we analyze certain
"optical" properties of the plasma. The whole setup is generalized to non
abelian strongly coupled plasmas engineered on D3-D7 systems with D3-branes
placed at the tip of a generic singular Calabi-Yau cone. In all the cases,
fundamental matter fields are introduced by means of homogeneously smeared
D7-branes and the flavor symmetry group is thus a product of abelian factors.Comment: 27 pages; v2: 29 pages, 1 (new) figure, new section 4.4 on optical
properties, references, comments added; v3: eq. (3.19), comments and a
reference adde
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