5,005 research outputs found
The computation of the cohomology rings of all groups of order 128
We describe the computation of the mod-2 cohomology rings of all 2328 groups
of order 128. One consequence is that all groups of order less than 256 satisfy
the strong form of Benson's Regularity Conjecture.Comment: 15 pages; revised versio
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Incremental closure for systems of two variables per inequality
Subclasses of linear inequalities where each inequality has at most two vari- ables are popular in abstract interpretation and model checking, because they strike a balance between what can be described and what can be efficiently computed. This paper focuses on the TVPI class of inequalities, for which each coefficient of each two variable inequality is unrestricted. An implied TVPI in- equality can be generated from a pair of TVPI inequalities by eliminating a given common variable (echoing resolution on clauses). This operation, called result , can be applied to derive TVPI inequalities which are entailed (implied) by a given TVPI system. The key operation on TVPI is calculating closure: satisfiability can be observed from a closed system and a closed system also simplifies the calculation of other operations. A closed system can be derived by repeatedly applying the result operator. The process of adding a single TVPI inequality to an already closed input TVPI system and then finding the closure of this augmented system is called incremental closure. This too can be calcu- lated by the repeated application of the result operator. This paper studies the calculus defined by result , the structure of result derivations, and how deriva- tions can be combined and controlled. A series of lemmata on derivations are presented that, collectively, provide a pathway for synthesising an algorithm for incremental closure. The complexity of the incremental closure algorithm is analysed and found to be O (( n 2 + m 2 )lg( m )), where n is the number of variables and m the number of inequalities of the input TVPI system
Be Decay Anomaly and Light
In this proceedings, we discuss a light (17 MeV) solution to the anomaly
observed in the decay of Beryllium-8 by the Atomki collaboration. We detail an
anomaly free model with minimal particle content which can satisfy all other
experimental constraints with gauge couplings .Comment: Prepared for the 2019 EW session of the 54th Rencontres de Moriond,
talk presented by Simon Kin
Naturalness and Dark Matter Properties of the BLSSM
In this report, we compare the naturalness and Dark Matter (DM) properties of
the Minimal Supersymmetric Standard Model (MSSM) and the Supersymmetric
Standard Model (BLSSM), with universality in both cases. We do this by adopting
standard measures for the quantitative analysis of the Fine-Tuning (FT), at
both low (i.e. supersymmetric (SUSY)) and high (i.e. unification) scales. We
will see a similar level of FT for both models in these scenarios, with a
slightly better FT for the BLSSM at SUSY scales and MSSM at Grand Unification
Theory (GUT) scales. When including DM relic constraints, we drastically
confine the MSSM's parameter space, whereas we still find a large parameter
space available for the non-minimal scenario.Comment: Prepared for proceedings for DIS2017, talk presented by Simon Kin
The covariance of cosmic shear correlation functions and cosmological parameter estimates using redshift information
Cosmological weak lensing by the large scale structure of the Universe,
cosmic shear, is coming of age as a powerful probe of the parameters describing
the cosmological model and matter power spectrum. It complements CMB studies,
by breaking degeneracies and providing a cross-check. An important measure of
the cosmic shear signal are the shear correlation functions; these can be
directly calculated from data, and compared with theoretical expectations for
different cosmological models and matter power spectra. We present a Monte
Carlo method to quickly simulate mock cosmic shear surveys. One application of
this method is in the determination of the full covariance matrix for the
correlation functions; this includes redshift binning and is applicable to
arbitrary survey geometries. Terms arising from shot noise and cosmic variance
(dominant on small and large scales respectively) are accounted for naturally.
As an illustration of the use of such covariance matrices, we consider to what
degree confidence regions on parameters are tightened when redshift binning is
employed. The parameters considered are those commonly discussed in cosmic
shear analyses - the matter density parameter, dark energy density parameter
(classical cosmological constant), power spectrum normalisation and shape
parameter. We incorporate our covariance matrices into a likelihood treatment,
and also use the Fisher formalism to explore a larger region of parameter space
(abridged).Comment: 14 pages, 8 figures, accepted by A&A corrected typos, some changes in
the discussion, shortened sections 2.1, 2.2 and 6.2.
Prospects for Sneutrino Dark Matter in the BLSSM
The Supersymmetric Standard Model (BLSSM) motivates several Dark
Matter (DM) candidates beyond the Minimally Supersymmetric Standard Model
(MSSM). We assess the comparative naturalness of the two models and discuss the
potential detection properties of a particular candidate, the Right-Handed (RH)
sneutrino.Comment: Prepared for proceedings for La Thuile 2018, talk by Simon Kin
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