252 research outputs found
On the Production of Flux Vortices and Magnetic Monopoles in Phase Transitions
We examine the basic assumptions underlying a scenario due to Kibble that is
widely used to estimate the production of topological defects. We argue that
one of the crucial assumptions, namely the geodesic rule, although completely
valid for global defects, becomes ill defined for the case of gauged defects.
We address the issues involved in formulating a suitable geodesic rule for this
case and argue that the dynamics plays an important role in the production of
gauge defects.Comment: 9 pages, in LATEX, UMN-TH-1028/92, TPI-MINN-92/20-
Self-compassion and compassion towards one’s partner mediate the negative association between insecure attachment and relationship quality.
The quality of intimate relationships has been found to be a strong negative predictor for individuals’ mental and physical health problems. A significant predictor of relationship quality is adult attachment insecurity, but the mechanism by which attachment insecurity affects relationship quality needs further investigation. This study investigated whether self-compassion and compassion for one’s partner mediated this association. Three-hundred-forty-two individuals participated in an online survey assessing attachment anxiety and avoidance, compassionate and uncompassionate attitude towards self and one’s partner, as well as relationship quality and relationship satisfaction. The results showed that low self-compassionate attitude mediated the association between attachment anxiety and poor relationship quality. Further, low compassionate and high uncompassionate attitude towards one’s partner mediated the association between attachment avoidance and poor relationship quality. No mediating effect was found for relationship satisfaction. Implications for interventions are discussed
Chiral Anomaly and
Measurement of the process has revealed a possible conflict
with what should be a solid prediction generated by the chiral anomaly. We show
that inclusion of appropirate energy-momentum dependence in the matrix element
reduces the discrepancy.Comment: 8 page standard Latex fil
Single Leptoquark Production at Hadron Colliders
Leptoquarks can be produced in pairs by gluon--gluon fusion and
quark--antiquark annihilation at hadron colliders. While HERA is the proper
machine for single production of and type leptoquarks, the flavor
species of (), () and (), () type leptoquarks can
be produced at hadron colliders very efficiently. Besides exploiting
gluon-quark collisions, leptoquarks can also be produced singly by colliding
the quarks in one proton beam with leptons generated by splitting
photons which are radiated off the quarks in the other proton beam. For Yukawa
couplings of the size leptoquark masses up to about 300~GeV can be
generated at the Tevatron while the LHC can produce leptoquarks with masses up
to about 3~TeV. [Leptoquarks involving heavy quarks can be produced singly at a
lower rate, determined by the heavy flavor flux in the proton beam.]Comment: 7 LaTex pages plus 2 uuencoded postscript files appended, DESY
94--086, UCD--94--17, UMN--TH--1258/94. Latex and postscipt files are also
available via anonymous ftp at ucdhep.ucdavis.edu in directory
[anonymous.ohnemus.ucd-94-17
Probing Gauge String Formation in a Superconducting Phase Transition
Superconductors are the only experimentally accessible systems with
spontaneously broken gauge symmetries which support topologically nontrivial
defects, namely string defects. We propose two experiments whose aim is the
observation of the dense network of these strings thought to arise, via the
Kibble mechanism, in the course of a spontaneous symmetry breaking phase
transition. We suggest ways to estimate the order of magnitude of the density
of flux tubes produced in the phase transition. This may provide an
experimental check for the theories of the production of topological defects in
a spontaneously broken gauge theory, such as those employed in the context of
the early Universe.Comment: 16 pages (Latex), 4 figures included, change in title, some minor
changes, published versio
Do bipolar subjects' responses to personality questionnaires lack reliability? Evidence from the PsyCoLaus study.
Differences in personality scores between subjects with and without mood disorders might result from response biases rather than specific personality traits per se. The aim of this study was to compare subjects with bipolar disorders (BPD) to non-bipolar subjects in terms of response quality to the NEO-FFI. Using data from the population-based cohort study PsyCoLaus, subjects were compared in terms of responses to the NEO-FFI, and indices of response quality were calculated. Hierarchical regression analyses were performed and controlled for sociodemographic factors, depressive episodes, dysthymia, anxiety disorders and substance use disorders. Consistent with the literature, subjects with BPD had higher scores in neuroticism and openness, and lower scores in conscientiousness. However, significant differences were measured for response reliability and validity. In particular, the indices of response quality including response reliability were lower in subjects with BPD suggesting that bipolar subjects might have more difficulty in providing consistent answers throughout questionnaires. However, regression models resulted in small associations between mania/hypomania and response quality, and showed that differences in response quality were mainly attributable to correlates of BPD instead of the presence of mania/hypomania itself. The current findings suggest that bipolar subjects' responses to questionnaires are biased, making them less reliable
Where are the Hedgehogs in Nematics?
In experiments which take a liquid crystal rapidly from the isotropic to the
nematic phase, a dense tangle of defects is formed. In nematics, there are in
principle both line and point defects (``hedgehogs''), but no point defects are
observed until the defect network has coarsened appreciably. In this letter the
expected density of point defects is shown to be extremely low, approximately
per initially correlated domain, as result of the topology
(specifically, the homology) of the order parameter space.Comment: 6 pages, latex, 1 figure (self-unpacking PostScript)
Psychiatric symptoms and response quality to self-rated personality tests: Evidence from the PsyCoLaus study.
Despite the fact that research has demonstrated consistent associations between self-rated measures of personality dimensions and mental disorders, little has been undertaken to investigate the relation between psychiatric symptoms and response patterns to self-rated tests. The aim of this study was to investigate the association between psychiatric symptoms and response quality using indices from our functional method. A sample of 1,784 participants from a Swiss population-based cohort completed a personality inventory (NEO-FFI) and a symptom checklist of 90 items (SCL-90-R). Different indices of response quality were calculated based on the responses given to the NEO-FFI. Associations among the responses to indices of response quality, sociodemographic characteristics and the SCL-90-R dimensions were then established. Psychiatric symptoms were associated with several important differences in response quality, questioning subjects' ability to provide valid information using self-rated instruments. As suggested by authors, psychiatric symptoms seem associated with differences in personality scores. Nonetheless, our study shows that symptoms are also related to differences in terms of response patterns as sources of differences in personality scores. This could constitute a bias for clinical assessment. Future studies could still determine whether certain subpopulations of subjects are more unable to provide valid information to self-rated questionnaires than others
How does the geodesic rule really work for global symmetry breaking first order phase transitions?
The chain of events usually understood to lead to the formation of
topological defects during phase transitions is known as the Kibble mechanism.
A central component of the mechanism is the so-called ``geodesic rule''.
Although in the Abelian Higgs model the validity of the geodesic rule has been
questioned recently, it is known to be valid on energetic grounds for a global
U(1) symmetry breaking transition. However, even for these globally symmetric
models no dynamical analisys of the rule has been carried to this date, and
some points as to how events proceed still remain obscure. This paper tries to
clarify the dynamics of the geodesic rule in the context of a global U(1)
model. With an appropriate ansatz for the field modulus we find a family of
analytical expressions, phase walls, that accounts for both geodesic and
nongeodesic configurations. We then show how the latter ones are unstable and
decay into the former by nucleating pairs of defects. Finnally, we try to give
a physical perspective of how the geodesic rule might really work in these
transitions.Comment: 10 pages, 9 multiple figre
Positrons from particle dark-matter annihilation in the Galactic halo: propagation Green's functions
We have made a calculation of the propagation of positrons from dark-matter
particle annihilation in the Galactic halo in different models of the dark
matter halo distribution using our 3D code, and present fits to our numerical
propagation Green's functions. We show that the Green's functions are not very
sensitive to the dark matter distribution for the same local dark matter energy
density. We compare our predictions with computed cosmic ray positron spectra
(``background'') for the ``conventional'' CR nucleon spectrum which matches the
local measurements, and a modified spectrum which respects the limits imposed
by measurements of diffuse Galactic gamma-rays, antiprotons, and positrons. We
conclude that significant detection of a dark matter signal requires favourable
conditions and precise measurements unless the dark matter is clumpy which
would produce a stronger signal. Although our conclusion qualitatively agrees
with that of previous authors, it is based on a more realistic model of
particle propagation and thus reduces the scope for future speculations.
Reliable background evaluation requires new accurate positron measurements and
further developments in modelling production and propagation of cosmic ray
species in the Galaxy.Comment: 8 pages, 6 ps-figures, 3 tables, uses revtex. Accepted for
publication in Physical Review D. More details can be found at
http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm
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