34,925 research outputs found
Jointly Sparse Support Recovery via Deep Auto-encoder with Applications in MIMO-based Grant-Free Random Access for mMTC
In this paper, a data-driven approach is proposed to jointly design the
common sensing (measurement) matrix and jointly support recovery method for
complex signals, using a standard deep auto-encoder for real numbers. The
auto-encoder in the proposed approach includes an encoder that mimics the noisy
linear measurement process for jointly sparse signals with a common sensing
matrix, and a decoder that approximately performs jointly sparse support
recovery based on the empirical covariance matrix of noisy linear measurements.
The proposed approach can effectively utilize the feature of common support and
properties of sparsity patterns to achieve high recovery accuracy, and has
significantly shorter computation time than existing methods. We also study an
application example, i.e., device activity detection in Multiple-Input
Multiple-Output (MIMO)-based grant-free random access for massive machine type
communications (mMTC). The numerical results show that the proposed approach
can provide pilot sequences and device activity detection with better detection
accuracy and substantially shorter computation time than well-known recovery
methods.Comment: 5 pages, 8 figures, to be publised in IEEE SPAWC 2020. arXiv admin
note: text overlap with arXiv:2002.0262
Heavy Higgs Bosons at Low : from the LHC to 100 TeV
We present strategies to search for heavy neutral Higgs bosons decaying to
top quark pairs, as often occurs at low in type II two Higgs
doublet models such as the Higgs sector of the MSSM. The resonant production
channel is unsatisfactory due to interference with the SM background. We
instead propose to utilize same-sign dilepton signatures arising from the
production of heavy Higgs bosons in association with one or two top quarks and
subsequent decay to a top pair. We find that for heavier neutral Higgs bosons
the production in association with one top quark provides greater sensitivity
than production in association with two top quarks. We obtain current limits at
the LHC using Run I data at 8 TeV and forecast the sensitivity of a dedicated
analysis during Run II at 14 TeV. Then we perform a detailed BDT study for the
14 TeV LHC and a future 100 TeV collider.Comment: published version, 22 pages, 15 figures, 3 table
Hawking-Moss instanton in nonlinear massive gravity
As a first step toward understanding a lanscape of vacua in a theory of
non-linear massive gravity, we consider a landscape of a single scalar field
and study tunneling between a pair of adjacent vacua. We study the Hawking-Moss
(HM) instanton that sits at a local maximum of the potential, and evaluate the
dependence of the tunneling rate on the parameters of the theory. It is found
that provided with the same physical HM Hubble parameter , depending on
the values of parameters and in the action, the
corresponding tunneling rate can be either enhanced or suppressed when compared
to the one in the context of General Relativity (GR). Furthermore, we find the
constraint on the ratio of the physical Hubble parameter to the fiducial one,
which constrains the form of potential. This result is in sharp contrast to GR
where there is no bound on the minimum value of the potential.Comment: v2, 14 pages, 3 figures, comments and references adde
Scalar suppression on large scales in open inflation
We consider two toy models of open inflation and investigate their ability to
give a suppression of scalar power on large scales whilst also satisfying
observational constraints on the spatial curvature of the universe.
Qualitatively we find that both models are indeed capable of fulfilling these
two requirements, but we also see that effects of the quantum tunnelling must
be carefully taken into account if we wish to make quantitative predictions.Comment: 11 pages, 13 figures. Updated to match published version: figures 7
and 11 updated, references added, typos correcte
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