738 research outputs found
Selective Decoding in Associative Memories Based on Sparse-Clustered Networks
Associative memories are structures that can retrieve previously stored
information given a partial input pattern instead of an explicit address as in
indexed memories. A few hardware approaches have recently been introduced for a
new family of associative memories based on Sparse-Clustered Networks (SCN)
that show attractive features. These architectures are suitable for
implementations with low retrieval latency, but are limited to small networks
that store a few hundred data entries. In this paper, a new hardware
architecture of SCNs is proposed that features a new data-storage technique as
well as a method we refer to as Selective Decoding (SD-SCN). The SD-SCN has
been implemented using a similar FPGA used in the previous efforts and achieves
two orders of magnitude higher capacity, with no error-performance penalty but
with the cost of few extra clock cycles per data access.Comment: 4 pages, Accepted in IEEE Global SIP 2013 conferenc
Low Q^2 Weak Mixing Angle Measurements and Rare Higgs Decays
A weighted average weak mixing angle theta_W derived from relatively low Q^2
experiments is compared with the Standard Model prediction obtained from
precision measurements. The approximate 1.8 sigma discrepancy is fit with an
intermediate mass (~ 10-35 GeV) "dark" Z boson Z_d, corresponding to a U(1)_d
gauge symmetry of hidden dark matter, which couples to our world via kinetic
and Z-Z_d mass mixing. Constraints on such a scenario are obtained from
precision electroweak bounds and searches for the rare Higgs decays H -> Z Z_d
-> 4 charged leptons at the LHC. The sensitivity of future anticipated low Q^2
measurements of sin^2 theta_W(Q^2) to intermediate mass Z_d is also
illustrated. This dark Z scenario can provide interesting concomitant signals
in low energy parity violating measurements and rare Higgs decays at the LHC,
over the next few years.Comment: Version to appear in PR
Strong CP, Up-Quark Mass, and the Randall-Sundrum Microscope
In the Randall-Sundrum model, setting the ratio of up and down quark masses
, relevant to the strong CP problem, does not require chiral
symmetry or fine-tuning, due to exponential bulk fermion profiles. We point out
that such geometric suppression of the mass of a fermion magnifies the masses
of its corresponding Kaluza-Klein (KK) states. In this sense, these KK states
act as "microscopes" for probing light quark and lepton masses. In simple
realizations, this hypothesis can be testable at future colliders, like the
LHC, by measuring the spectrum of level-1 KK fermions. The microscope can then
provide an experimental test for the vanishing of in the ultraviolet,
independently of non-perturbative determinations, by lattice simulations or
other means, at hadronic scales. We also briefly comment on application of our
microscope idea to other fermions, such as the electron and neutrinos.Comment: 7 pages. New discussions and references added. Main previous
conclusions unchange
The Radion as a Harbinger of Deca-TeV Physics
Precision data generally require the threshold for physics beyond the
Standard Model to be at the deca-TeV (10 TeV) scale or higher. This raises the
question of whether there are interesting deca-TeV models for which the LHC may
find direct clues. A possible scenario for such physics is a 5D warped model of
fermion masses and mixing, with Kaluza-Klein masses m_KK ~ 10 TeV, allowing it
to avoid tension with stringent constraints, especially from flavor data.
Discovery of a Standard-Model-like Higgs boson, for which there are some hints
at ~125 GeV at the LHC, would also require the KK masses to be at or above 10
TeV. These warped models generically predict the appearance of a much lighter
radion scalar. We find that, in viable warped models of flavor, a radion with a
mass of a few hundred GeV and an inverse coupling of order m_KK ~ 10 TeV could
typically be accessible to the LHC experiments -- with sqrt(s) = 14 TeV and 100
fb^-1 of data. The above statements can be applied, mutatis mutandis, to 4D
dual models, where conformal dynamics and a dilaton replace warping and the
radion, respectively. Detection of such a light and narrow scalar could thus
herald the proximity of a new physical threshold and motivate experiments that
would directly probe the deca-TeV mass scale.Comment: 18 pages, 5 figures; version published in Physical Review
Precocious Diphoton Signals of the Little Radion at Hadron Colliders
In Little Randall-Sundrum models, the bulk couplings of the radion to
massless gauge fields can yield a greatly enhanced diphoton signal at hadron
colliders. We examine the implications of the Tevatron data for the Little
radion and also show that the 7 TeV run at the Large Hadron Collider will have
an impressive reach in this channel. The diphoton signal is crucial in the
search for a light radion, or the dual dilaton, and can potentially probe the
ultraviolet scale of the theory.Comment: 5 pages, 2 figures. Errors in the WW and ZZ branching fraction curves
in Fig.1 and the related numerical results in Fig.2 have been corrected. New
references have been added. Our main conclusions regarding the enhanced
diphoton signal of the Little radion remain qualitatively the same and
quantitatively similar to the previous result
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