8,605 research outputs found
Remove-Win: a Design Framework for Conflict-free Replicated Data Collections
Internet-scale distributed systems often replicate data within and across
data centers to provide low latency and high availability despite node and
network failures. Replicas are required to accept updates without coordination
with each other, and the updates are then propagated asynchronously. This
brings the issue of conflict resolution among concurrent updates, which is
often challenging and error-prone. The Conflict-free Replicated Data Type
(CRDT) framework provides a principled approach to address this challenge.
This work focuses on a special type of CRDT, namely the Conflict-free
Replicated Data Collection (CRDC), e.g. list and queue. The CRDC can have
complex and compound data items, which are organized in structures of rich
semantics. Complex CRDCs can greatly ease the development of upper-layer
applications, but also makes the conflict resolution notoriously difficult.
This explains why existing CRDC designs are tricky, and hard to be generalized
to other data types. A design framework is in great need to guide the
systematic design of new CRDCs.
To address the challenges above, we propose the Remove-Win Design Framework.
The remove-win strategy for conflict resolution is simple but powerful. The
remove operation just wipes out the data item, no matter how complex the value
is. The user of the CRDC only needs to specify conflict resolution for
non-remove operations. This resolution is destructed to three basic cases and
are left as open terms in the CRDC design skeleton. Stubs containing
user-specified conflict resolution logics are plugged into the skeleton to
obtain concrete CRDC designs. We demonstrate the effectiveness of our design
framework via a case study of designing a conflict-free replicated priority
queue. Performance measurements also show the efficiency of the design derived
from our design framework.Comment: revised after submissio
Searching for the signal of dark matter and photon associated production at the LHC beyond leading order
We study the signal of dark matter and photon associated production induced
by the vector and axial-vector operators at the LHC, including the QCD
next-to-leading order (NLO) effects. We find that the QCD NLO corrections
reduce the dependence of the total cross sections on the factorization and
renormalization scales, and the factors increase with the increasing of the
dark matter mass, which can be as large as about 1.3 for both the vector and
axial-vector operators. Using our QCD NLO results, we improve the constraints
on the new physics scale from the results of the recent CMS experiment.
Moreover, we show the Monte Carlo simulation results for detecting the
\gamma+\Slash{E}_{T} signal at the QCD NLO level, and present the integrated
luminosity needed for a discovery at the 14 TeV LHC . If the signal
is not observed, the lower limit on the new physics scale can be set.Comment: 19 pages, 18 figures, 2 tables, version published in Phys.Rev.
Phenomenology of an Extended Higgs Portal Inflation Model after Planck 2013
We consider an extended inflation model in the frame of Higgs portal model,
assuming a nonminimal coupling of the scalar field to the gravity. Using the
new data from Planck and other relevant astrophysical data, we obtain
the relation between the nonminimal coupling and the self-coupling
needed to drive the inflation, and find that this inflationary model
is favored by the astrophysical data. Furthermore, we discuss the constraints
on the model parameters from the experiments of particle physics, especially
the recent Higgs data at the LHC.Comment: 21 pages, 8 figures; Version published in EPJ
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