1,863 research outputs found
Critical behavior of a cellular automaton highway traffic model
We derive the critical behavior of a CA traffic flow model using an order
parameter breaking the symmetry of the jam-free phase. Random braking appears
to be the symmetry-breaking field conjugate to the order parameter. For
, we determine the values of the critical exponents ,
and using an order-3 cluster approximation and computer
simulations. These critical exponents satisfy a scaling relation, which can be
derived assuming that the order parameter is a generalized homogeneous function
of and p in the vicinity of the phase transition point.Comment: 6 pages, 12 figure
Cornering pseudoscalar-mediated dark matter with the LHC and cosmology
Models in which dark matter particles communicate with the visible sector through a pseudoscalar mediator are well-motivated both from a theoretical and from a phenomenological standpoint. With direct detection bounds being typically subleading in such scenarios, the main constraints stem either from collider searches for dark matter, or from indirect detection experiments. However., LHC searches for the mediator particles themselves can not only compete with — or even supersede — the reach of direct collider dark matter probes, but they can also test scenarios in which traditional monojet searches become irrelevant, especially when the mediator cannot decay on-shell into dark matter particles or its decay is suppressed. In this work we perform a detailed analysis of a pseudoscalar-mediated dark matter simplified model, taking into account a large set of collider constraints and concentrating on the parameter space regions favoured by cos-mological and astrophysical data. We find that mediator masses above 100-200 GeV are essentially excluded by LHC searches in the case of large couplings to the top quark, while forthcoming collider and astrophysical measurements will further constrain the available parameter space
Chern-Simons action for inhomogeneous Virasoro group as an extension of three dimensional flat gravity
We initiate the study of a Chern-Simons action associated to the semi-direct
sum of the Virasoro algebra with its coadjoint representation. This model
extends the standard Chern-Simons formulation of three dimensional flat gravity
and is similar to the higher-spin extension of three dimensional anti-de Sitter
or flat gravity. The extension can also be constructed for the exotic but not
for the cosmological constant deformation of flat gravity.Comment: 15 pages. Version to appear in J. of Math. Phy
SDiff(2) and uniqueness of the Pleba\'{n}ski equation
The group of area preserving diffeomorphisms showed importance in the
problems of self-dual gravity and integrability theory. We discuss how
representations of this infinite-dimensional Lie group can arise in
mathematical physics from pure local considerations. Then using Lie algebra
extensions and cohomology we derive the second Pleba\'{n}ski equation and its
geometry. We do not use K\"ahler or other additional structures but obtain the
equation solely from the geometry of area preserving transformations group. We
conclude that the Pleba\'{n}ski equation is Lie remarkable
Odd Chern-Simons Theory, Lie Algebra Cohomology and Characteristic Classes
We investigate the generic 3D topological field theory within AKSZ-BV
framework. We use the Batalin-Vilkovisky (BV) formalism to construct explicitly
cocycles of the Lie algebra of formal Hamiltonian vector fields and we argue
that the perturbative partition function gives rise to secondary characteristic
classes. We investigate a toy model which is an odd analogue of Chern-Simons
theory, and we give some explicit computation of two point functions and show
that its perturbation theory is identical to the Chern-Simons theory. We give
concrete example of the homomorphism taking Lie algebra cocycles to
Q-characteristic classes, and we reinterpreted the Rozansky-Witten model in
this light.Comment: 52 page
George Engel's Epistemology of Clinical Practice.
George Engel's (1913-1999) biopsychosocial model, one of the most significant proposals for the renewal of medicine in the latter half of the 20th century, has been understood primarily as a multi-factorial approach to the etiology of disease and as a call to re-humanize clinical practice. This common reading of Engel's model misses the central aspect of his proposal, that the biopsychosocial model is an epistemology for clinical work. By stating the simple fact that the clinician is not dealing directly with a body, but first, and inevitably, with a person, Engel challenged the epistemology implicit in the classical clinical method-a method predicated on the possibility of direct access to the body. Framed in epistemological terms, the issue at stake is not the need to complement medical science with humane virtues, but rather to acknowledge that the object of clinical practice is not the body but the patient
Monojet searches for momentum-dependent dark matter interactions
We consider minimal dark matter scenarios featuring momentum-dependent couplings of the dark sector to the Standard Model. We derive constraints from existing LHC searches in the monojet channel, estimate the future LHC sensitivity for an integrated luminosity of 300 fb−1, and compare with models exhibiting conventional momentum-independent interactions with the dark sector. In addition to being well motivated by (composite) pseudo-Goldstone dark matter scenarios, momentum-dependent couplings are interesting as they weaken direct detection constraints. For a specific dark matter mass, the LHC turns out to be sensitive to smaller signal cross-sections in the momentum-dependent case, by virtue of the harder jet transverse-momentum distribution
Cyclic Statistics In Three Dimensions
While 2-dimensional quantum systems are known to exhibit non-permutation,
braid group statistics, it is widely expected that quantum statistics in
3-dimensions is solely determined by representations of the permutation group.
This expectation is false for certain 3-dimensional systems, as was shown by
the authors of ref. [1,2,3]. In this work we demonstrate the existence of
``cyclic'', or , {\it non-permutation group} statistics for a system of n
> 2 identical, unknotted rings embedded in . We make crucial use of a
theorem due to Goldsmith in conjunction with the so called Fuchs-Rabinovitch
relations for the automorphisms of the free product group on n elements.Comment: 13 pages, 1 figure, LaTex, minor page reformattin
Cohomology of Lie superalgebras and of their generalizations
The cohomology groups of Lie superalgebras and, more generally, of color Lie
algebras, are introduced and investigated. The main emphasis is on the case
where the module of coefficients is non-trivial. Two general propositions are
proved, which help to calculate the cohomology groups. Several examples are
included to show the peculiarities of the super case. For L = sl(1|2), the
cohomology groups H^1(L,V) and H^2(L,V), with V a finite-dimensional simple
graded L-module, are determined, and the result is used to show that
H^2(L,U(L)) (with U(L) the enveloping algebra of L) is trivial. This implies
that the superalgebra U(L) does not admit of any non-trivial formal
deformations (in the sense of Gerstenhaber). Garland's theory of universal
central extensions of Lie algebras is generalized to the case of color Lie
algebras.Comment: 50 pages, Latex, no figures. In the revised version the proof of
Lemma 5.1 is greatly simplified, some references are added, and a pertinent
result on sl(m|1) is announced. To appear in the Journal of Mathematical
Physic
Electroweak superpartner production at 13.6 TeV with Resummino
Due to the greater experimental precision expected from the currently ongoing
LHC Run 3, equally accurate theoretical predictions are essential. We update
the documentation of the Resummino package, a program dedicated to precision
cross section calculations for the production of a pair of sleptons,
electroweakinos, and leptons in the presence of extra gauge bosons, and for the
production of an associated electroweakino-squark or electroweakino-gluino
pair. We detail different additions that have been released since the initial
version of the program a decade ago, and then use the code to investigate the
impact of threshold resummation corrections at the
next-to-next-to-leading-logarithmic accuracy. As an illustration of the code we
consider the production of pairs of electroweakinos and sleptons at the LHC for
centre-of-mass energies ranging up to 13.6 TeV and in simplified model
scenarios. We find slightly increased total cross section values, accompanied
by a significant decrease of the associated theoretical uncertainties.
Furthermore, we explore the dependence of the results on the squark masses.Comment: 30 pages, 5 figure
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