349 research outputs found
Phase transitions in a three-dimensional analogue of Klebanov-Strassler
We use top-down holography to study the thermodynamics of a one-parameter family of three-dimensional, strongly coupled Yang-Mills-Chern-Simons theories with M-theory duals. For generic values of the parameter, the theories exhibit a mass gap but no confinement, meaning no linear quark-antiquark potential. For two specific values of the parameter they flow to an infrared fixed point or to a confining vacuum, respectively. As in the Klebanov-Strassler solution, on the gravity side the mass gap is generated by the smooth collapse to zero size of a cycle in the internal geometry. We uncover a rich phase diagram with thermal phase transitions of first and second order, a triple point and a critical point
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
Pain coping and acceptance as longitudinal predictors of health-related quality of life among people with haemophilia-related joint pain
Interventions based on coping and acceptance can be adapted for people with different painful conditions. Evidence about baseline characteristics that predict improved outcomes is informative for matching people to interventions, whereas evidence about changes that predict improved outcomes is informative about the processes that interventions should target. Participants in a low-intensity program to promote self-management of hemophilia-related chronic joint pain (n=101) reported pain intensity, coping, acceptance and quality of life at baseline and 6-month follow-up. Baseline and change measures of pain intensity, coping and acceptance were used to predict follow-up quality of life, taking account of baseline quality of life. Changed (reduced) pain intensity predicted better physical quality of life, independently of age, hemophilia severity, baseline pain intensity and baseline physical quality of life. Lower baseline passive coping and changed (increased) pain acceptance predicted better mental quality of life, independently of age, severity, and baseline mental quality of life. Increased activity engagement but not pain willingness predicted better mental quality of life when pain acceptance was decomposed. Changed (reduced) negative thoughts also predicted better mental quality of life when separate acceptance subscales were used. Active pain coping did not predict physical or mental quality of life. Initially high levels of passive coping may be an obstacle to improving mental quality of life. Acceptance rather than coping may be a more useful behavioral change target, but more research is needed about the meanings and therapeutic implications of different elements of pain acceptance.The Haemophilia Society UK and the Institute for Health Policy and Research, London Metropolitan University
Pade approximation of the S-matrix as a way of locating quantum resonances and bound states
It is shown that the spectral points (bound states and resonances) generated
by a central potential of a single-channel problem, can be found using rational
parametrization of the S-matrix. To achieve this, one only needs values of the
S-matrix along the real positive energy axis. No calculations of the S-matrix
at complex energies or a complex rotation are necessary. The proposed method is
therefore universal in that it is applicable to any potential (local,
non-local, discontinuous, etc.) provided that there is a way of obtaining the
S-matrix (or scattering phase-shifts) at real collision energies. Besides this,
combined with any method that extracts the phase-shifts from the scattering
data, the proposed rational parametrization technique would be able to do the
spectral analysis using the experimental data.Comment: 20 pages, 6 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 studentsâ 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: âauthorial confidenceâ, âvaluing writingâ and âidentification with authorâ. 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
Logarithmic perturbation theory for quasinormal modes
Logarithmic perturbation theory (LPT) is developed and applied to quasinormal
modes (QNMs) in open systems. QNMs often do not form a complete set, so LPT is
especially convenient because summation over a complete set of unperturbed
states is not required. Attention is paid to potentials with exponential tails,
and the example of a Poschl-Teller potential is briefly discussed. A numerical
method is developed that handles the exponentially large wavefunctions which
appear in dealing with QNMs.Comment: 24 pages, 4 Postscript figures, uses ioplppt.sty and epsfig.st
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
Glueball masses in the large N limit
The lowest-lying glueball masses are computed in SU() gauge theory on a
spacetime lattice for constant value of the lattice spacing and for
ranging from 3 to 8. The lattice spacing is fixed using the deconfinement
temperature at temporal extension of the lattice . The calculation is
conducted employing in each channel a variational ansatz performed on a large
basis of operators that includes also torelon and (for the lightest states)
scattering trial functions. This basis is constructed using an automatic
algorithm that allows us to build operators of any size and shape in any
irreducible representation of the cubic group. A good signal is extracted for
the ground state and the first excitation in several symmetry channels. It is
shown that all the observed states are well described by their large
values, with modest corrections. In addition spurious states
are identified that couple to torelon and scattering operators. As a byproduct
of our calculation, the critical couplings for the deconfinement phase
transition for N=5 and N=7 and temporal extension of the lattice are
determined.Comment: 1+36 pages, 22 tables, 21 figures. Typos corrected, conclusions
unchanged, matches the published versio
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