2,006 research outputs found
The algebra of adjacency patterns: Rees matrix semigroups with reversion
We establish a surprisingly close relationship between universal Horn classes
of directed graphs and varieties generated by so-called adjacency semigroups
which are Rees matrix semigroups over the trivial group with the unary
operation of reversion. In particular, the lattice of subvarieties of the
variety generated by adjacency semigroups that are regular unary semigroups is
essentially the same as the lattice of universal Horn classes of reflexive
directed graphs. A number of examples follow, including a limit variety of
regular unary semigroups and finite unary semigroups with NP-hard variety
membership problems.Comment: 30 pages, 9 figure
Implementing NICE guidelines for the psychological treatment of depression and anxiety disorders: The IAPT experience
The Improving Access to Psychological Therapies (IAPT) programme is a large-scale initiative that aims to greatly increase the availability of NICE recommended psychological treatment for depression and anxiety disorders within the National Health Service in England. This article describes the background to the programme, the arguments on which it is based, the therapist training scheme, the clinical service model, and a summary of progress to date. At mid-point in a national roll-out of the programme progress is generally in line with expectation, and a large number of people who would not otherwise have had the opportunity to receive evidence-based psychological treatment have accessed, and benefited from, the new IAPT services. Planned future developments and challenges for the programme are briefly described
Consistent deformations method applied to a topological coupling of antisymmetric gauge fields in D=3
In this work we use the method of consistent deformations of the master
equation by Barnich and Henneaux in order to prove that an abelian topological
coupling between a zero and a two form fields in D=3 has no nonabelian
generalization. We conclude that a topologically massive model involving the
Kalb-Ramond two-form field does not admit a nonabelian generalization. The
introduction of a connection-type one form field keeps the previous result.Comment: 8 pages. To appear in Physics Letters
Goldstino and sgoldstino in microscopic models and the constrained superfields formalism
We examine the exact relation between the superconformal symmetry breaking
chiral superfield (X) and the goldstino superfield in microscopic models of an
arbitrary Kahler potential (K) and in the presence of matter fields. We
investigate the decoupling of the massive sgoldstino and scalar matter fields
and the offshell/onshell-SUSY expressions of their superfields in terms of the
fermions composites. For general K of two superfields, we study the properties
of the superfield X after integrating out these scalar fields, to show that in
the infrared it satisfies (offshell) the condition and . We
then compare our results to those of the well-known method of constrained
superfields discussed in the literature, based on the conjecture . Our
results can be used in applications, to couple offshell the (s)goldstino fields
to realistic models such as the MSSM.Comment: 24 page
Annealing Effect for Supersolid Fraction in He
We report on experimental confirmation of the non-classical rotational
inertia (NCRI) in solid helium samples originally reported by Kim and Chan. The
onset of NCRI was observed at temperatures below ~400 mK. The ac velocity for
initiation of the NCRI suppression is estimated to be ~10 m/sec. After an
additional annealing of the sample at K for 12 hours, ~ 10% relative
increase of NCRI fraction was observed. Then after repeated annealing with the
same conditions, the NCRI fraction was saturated. It differs from Reppy's
observation on a low pressure solid sample.Comment: to be published in J. of Low Temp. Phys. (QFS2006 proceedings
Non-linear MSSM
Using the formalism of constrained superfields, we derive the most general
effective action of a light goldstino coupled to the minimal supersymmetric
standard model (MSSM) and study its phenomenological consequences. The
goldstino-induced couplings become important when the (hidden sector) scale of
spontaneous supersymmetry breaking, , is relatively low, of the order
of few TeV. In particular, we compute the Higgs potential and show that the
(tree level) mass of the lightest Higgs scalar can be increased to the LEP
bound for TeV to 7 TeV. Moreover, the effective quartic Higgs
coupling is increased due to additional tree-level contributions proportional
to the ratio of visible to hidden sector supersymmetry breaking scales. This
increase can alleviate the amount of fine tuning of the electroweak scale that
exists in the MSSM. Among the new goldstino couplings, beyond those in MSSM,
the most important ones generate an invisible decay of the Higgs boson into a
goldstino and neutralino (if m_h>m_{\chi_1^0}), with a partial decay rate that
can be comparable to the SM channel h^0-> \gamma\gamma. A similar decay of Z
boson is possible if m_Z>m_{\chi_1^0} and brings a lower bound on
that must be of about 700 GeV. Additional decay modes of the Higgs or Z bosons
into a pair of light goldstinos, while possible, are suppressed by an extra 1/f
factor and have no significant impact on the model.Comment: 25 pages, LaTeX, 8 figures; v3: added reference
On non-universal Goldstino couplings to matter
Using the constrained superfields formalism to describe the interactions of a
light goldstino to matter fields in supersymmetric models, we identify
generalised, higher-order holomorphic superfield constraints that project out
the superpartners and capture the non-universal couplings of the goldstino to
matter fields. These arise from microscopic theories in which heavy
superpartners masses are of the order of the supersymmetry breaking scale
(\sqrt f). In the decoupling limit of infinite superpartners masses, these
constraints reduce to the familiar, lower-order universal constraints discussed
recently, that describe the universal goldstino-matter fields couplings,
suppressed by inverse powers of \sqrt f. We initiate the study of the couplings
of the Standard Model (SM) fields to goldstino in the constrained superfields
formalism.Comment: 28 pages; one comment adde
The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop
The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target
Ideal Gases in Time-Dependent Traps
We investigate theoretically the properties of an ideal trapped gas in a
time-dependent harmonic potential. Using a scaling formalism, we are able to
present simple analytical results for two important classes of experiments:
free expansion of the gas upon release of the trap; and the response of the gas
to a harmonic modulation of the trapping potential is investigated. We present
specific results relevant to current experiments on trapped Fermions.Comment: 5 pages, 3 eps figure
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