52 research outputs found
mu -> e gamma in a supersymmetric radiative neutrino mass model
We consider a supersymmetric version of the inert Higgs doublet model, whose motivation is to explain smallness of neutrino masses and existence of dark matter. In this supersymmetric model, due to the presence of discrete symmetries, neutrinos acquire masses at loop level. After computing these neutrino masses, in order to fit the neutrino oscillation data, we show that by tuning some supersymmetry-breaking soft parameters of the model, neutrino Yukawa couplings can be unsuppressed. In the above-mentioned parameter space, we compute the branching ratio of the decay μ→eγ. To be consistent with the current experimental upper bound on Br(μ→eγ), we obtain constraints on the right-handed neutrino mass of this model
Study on the global minimum and in the Dirac scotogenic model
We have analyzed the vacuum structure of the Dirac scotogenic model, whose
scalar sector consists of two complex Higgs doublets and a real singlet field.
In this model, the standard model like Higgs doublet acquires non-zero vacuum
expectation value (VEV), whereas, the other two fields acquire zero VEVs. This
pattern of VEVs constitute a minimum, which is the desired vacuum of the model.
After analyzing the scalar potential of this model, we have found that other
vacua are also possible in this model. We have shown that plenty of parameter
space exist where the desired vacuum of this model is the global minimum. We
have studied the implications of scalar sector of this model on the observable
quantity of signal strength of Higgs to diphoton decay. After evaluating this
quantity, we have found that the current experimental values of this quantity
can be fitted in this model. Lastly, we have studied on the possibility of
making any of the additional scalar fields of this model as a candidate for
dark matter.Comment: 42 pages, 1 figure, 7 tables; added Sec. 8 and more phenomenological
discussions; published in Phys. Rev.
QuickCast: Fast and Efficient Inter-Datacenter Transfers using Forwarding Tree Cohorts
Large inter-datacenter transfers are crucial for cloud service efficiency and
are increasingly used by organizations that have dedicated wide area networks
between datacenters. A recent work uses multicast forwarding trees to reduce
the bandwidth needs and improve completion times of point-to-multipoint
transfers. Using a single forwarding tree per transfer, however, leads to poor
performance because the slowest receiver dictates the completion time for all
receivers. Using multiple forwarding trees per transfer alleviates this
concern--the average receiver could finish early; however, if done naively,
bandwidth usage would also increase and it is apriori unclear how best to
partition receivers, how to construct the multiple trees and how to determine
the rate and schedule of flows on these trees. This paper presents QuickCast, a
first solution to these problems. Using simulations on real-world network
topologies, we see that QuickCast can speed up the average receiver's
completion time by as much as while only using more
bandwidth; further, the completion time for all receivers also improves by as
much as faster at high loads.Comment: [Extended Version] Accepted for presentation in IEEE INFOCOM 2018,
Honolulu, H
Neutrino masses and lepton-number violation in the Littlest Higgs scenario
We investigate the sources of neutrino mass generation in Little Higgs
theories, by confining ourselves to the "Littlest Higgs" scenario. Our
conclusion is that the most satisfactory way of incorporating neutrino masses
is to include a lepton-number violating interaction between the scalar triplet
and lepton doublets. The tree-level neutrino masses generated by the vacuum
expectation value of the triplet are found to dominate over contributions from
dimension-five operators so long as no additional large lepton-number violating
physics exists at the cut-off scale of the effective theory. We also calculate
the various decay branching ratios of the charged and neutral scalar triplet
states, in regions of the parameter space consistent with the observed neutrino
masses, hoping to search for signals of lepton-number violating interactions in
collider experiments.Comment: 27 pages, 4 figures. v2: minor clarifications in discussion, version
to appear in PR
DCCast: Efficient Point to Multipoint Transfers Across Datacenters
Using multiple datacenters allows for higher availability, load balancing and
reduced latency to customers of cloud services. To distribute multiple copies
of data, cloud providers depend on inter-datacenter WANs that ought to be used
efficiently considering their limited capacity and the ever-increasing data
demands. In this paper, we focus on applications that transfer objects from one
datacenter to several datacenters over dedicated inter-datacenter networks. We
present DCCast, a centralized Point to Multi-Point (P2MP) algorithm that uses
forwarding trees to efficiently deliver an object from a source datacenter to
required destination datacenters. With low computational overhead, DCCast
selects forwarding trees that minimize bandwidth usage and balance load across
all links. With simulation experiments on Google's GScale network, we show that
DCCast can reduce total bandwidth usage and tail Transfer Completion Times
(TCT) by up to compared to delivering the same objects via independent
point-to-point (P2P) transfers.Comment: 9th USENIX Workshop on Hot Topics in Cloud Computing,
https://www.usenix.org/conference/hotcloud17/program/presentation/noormohammadpou
Bilarge neutrino mixing in R-parity violating supersymmetry: the role of right-chiral neutrino superfields
We consider the possibility of neutrino mass generation in a supersymmetric
model where lepton number can be violated by odd units. The different patterns
of mixing in the quark and lepton sectors are attributed to the persence of
right-chiral neutrino superfields which (a) enter into Yukawa couplings via
non-renormalizable interaction with hidden sector fields, and (b) can violate
lepton number by odd units. Both of these features are shown to be the result
of some global quantum number which is violated when SUSY is broken in the
hidden sector. It is shown how such a scenario, together with all known
R-parity violating effects, can lead to neutrino masses and bilarge mixing via
seesaw as well as radiative mechanisms. Some sample values of the various
parameters involved, consistent with electroweak symmetry breaking constraints,
are presented as illustrations.Comment: 19 pages. Minor modificaitons are made in the text. This version is
to appear in Physical Review
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