17,758 research outputs found
Dynamic Poisson Factorization
Models for recommender systems use latent factors to explain the preferences
and behaviors of users with respect to a set of items (e.g., movies, books,
academic papers). Typically, the latent factors are assumed to be static and,
given these factors, the observed preferences and behaviors of users are
assumed to be generated without order. These assumptions limit the explorative
and predictive capabilities of such models, since users' interests and item
popularity may evolve over time. To address this, we propose dPF, a dynamic
matrix factorization model based on the recent Poisson factorization model for
recommendations. dPF models the time evolving latent factors with a Kalman
filter and the actions with Poisson distributions. We derive a scalable
variational inference algorithm to infer the latent factors. Finally, we
demonstrate dPF on 10 years of user click data from arXiv.org, one of the
largest repository of scientific papers and a formidable source of information
about the behavior of scientists. Empirically we show performance improvement
over both static and, more recently proposed, dynamic recommendation models. We
also provide a thorough exploration of the inferred posteriors over the latent
variables.Comment: RecSys 201
First-Principles Correlated Approach to the Normal State of Strontium Ruthenate
The interplay between multiple bands, sizable multi-band electronic
correlations and strong spin-orbit coupling may conspire in selecting a rather
unusual unconventional pairing symmetry in layered SrRuO. This
mandates a detailed revisit of the normal state and, in particular, the
-dependent incoherence-coherence crossover. Using a modern first-principles
correlated view, we study this issue in the actual structure of
SrRuO and present a unified and quantitative description of a range
of unusual physical responses in the normal state. Armed with these, we propose
that a new and important element, that of dominant multi-orbital charge
fluctuations in a Hund's metal, may be a primary pair glue for unconventional
superconductivity. Thereby we establish a connection between the normal state
responses and superconductivity in this system.Comment: 8 pages, 4 figure
Type IIA Orientifold Limit of M-Theory on Compact Joyce 8-Manifold of Spin(7)-Holonomy
We show that M-theory compactified on a compact Joyce 8-manifold of
-holonomy, which yields an effective theory in with = 1
supersymmetry, admits at some special points in it moduli space a description
in terms of type IIA theory on an orientifold of compact Joyce 7-manifold of
-holonomy. We find the evidence in favour of this duality by computing the
massless spectra on both M-thory side and type IIA side. For the latter, we
compute the massless spectra by going to the orbifold limit of the Joyce
7-manifold.Comment: 26 pages, 2 eps figures, Latex file, two references and one footnote
added, corrected some typo
Rotating membranes on G_2 manifolds, logarithmic anomalous dimensions and N=1 duality
We show that the behaviour found for long strings rotating
on may be reproduced by membranes rotating on and on a warped M-theory solution. We go on to obtain rotating
membrane configurations with the same relation on
holonomy backgrounds that are dual to gauge theories in four
dimensions. We study membrane configurations on holonomy backgrounds
systematically, finding various other Energy-Charge relations. We end with some
comments about strings rotating on warped backgrounds.Comment: 1+44 pages. Latex. No figures. Minor corrections to make all membrane
configurations consistent. One configuration is now noncompac
Kahler Independence of the G2-MSSM
The G2-MSSM is a model of particle physics coupled to moduli fields with
interesting phenomenology both for colliders and astrophysical experiments. In
this paper we consider a more general model - whose moduli Kahler potential is
a completely arbitrary G2-holonomy Kahler potential and whose matter Kahler
potential is also more general. We prove that the vacuum structure and spectrum
of BSM particles is largely unchanged in this much more general class of
theories. In particular, gaugino masses are still supressed relative to the
gravitino mass and moduli masses. We also consider the effects of higher order
corrections to the matter Kahler potential and find a connection between the
nature of the LSP and flavor effects.Comment: Final version, matches the version published in JHE
Comments on M Theory Dynamics on G2 Holonomy Manifolds
We study the dynamics of M-theory on G2 holonomy manifolds, and consider in
detail the manifolds realized as the quotient of the spin bundle over S^3 by
discrete groups. We analyse, in particular, the class of quotients where the
triality symmetry is broken. We study the structure of the moduli space,
construct its defining equations and show that three different types of
classical geometries are interpolated smoothly. We derive the N=1
superpotentials of M-theory on the quotients and comment on the membrane
instanton physics. Finally, we turn on Wilson lines that break gauge symmetry
and discuss some of the implications.Comment: 21pages, Latex2e. v2: minor change
A Note on Mirror Symmetry for Manifolds with Spin(7) Holonomy
Starting from the superconformal algebras associated with manifolds, I
extend the algebra to the manifolds with spin(7) holonomy. I show how the
mirror symmetry in manifolds with spin(7) holonomy arises as the automorphism
in the extended sperconformal algebra. The automorphism is realized as 14 kinds
of T-dualities on the supersymmetric toroidal fibrations. One class of
Joyce's orbifolds are pairwise identified under the symmetry.Comment: 12 pages, harvmac bi
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