18,464 research outputs found
Electroweak Beautygenesis: From b {\to} s CP-violation to the Cosmic Baryon Asymmetry
We address the possibility that CP-violation in mixing may
help explain the origin of the cosmic baryon asymmetry. We propose a new
baryogenesis mechanism - "Electroweak Beautygenesis" - explicitly showing that
these two CP-violating phenomena can be sourced by a common CP-phase. As an
illustration, we work in the Two-Higgs-Doublet model. Because the relevant
CP-phase is flavor off-diagonal, this mechanism is less severely constrained by
null results of electric dipole moment searches than other scenarios. We show
how measurements of flavor observables by the D0, CDF, and LHCb collaborations
test this scenario.Comment: 4 pages, 1 figure, 1 tabl
Retrospective-Cost Adaptive Control of Uncertain Hammerstein Systems Using a NARMAX Controller Structure
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97107/1/AIAA2012-4448.pd
Black hole evaporation with separated fermions
In models with a low quantum gravity scale, a well-motivated reason to expect
quark and lepton fields are localized but physically separated is to avoid
proton decay. This could happen in a ``fat-brane'' or in an additional,
orthogonal 1/TeV sized dimension in which the gauge and Higgs fields live
throughout. Black holes with masses of order the quantum gravity scale are
therefore expected to evaporate non-universally, preferentially radiating
directly into quarks or leptons but not both. Should black holes be copiously
produced at a future hadron collider, we find the ratio of final state jets to
charged leptons to photons is 113:8:1, which differs from previous analyses
that assumed all standard model fields live at the same point in the extra
dimensional space.Comment: 5 pages, REVTe
Terahertz metamaterials on free-standing highly-flexible polyimide substrates
We have fabricated resonant terahertz metamaterials on free standing
polyimide substrates. The low-loss polyimide substrates can be as thin as 5.5
micron yielding robust large-area metamaterials which are easily wrapped into
cylinders with a radius of a few millimeters. Our results provide a path
forward for creating multi-layer non-planar metamaterials at terahertz
frequencies.Comment: 4 pages, higher resolution figures available upon reques
Signal of the pion string at high-energy collisions
We study the possible signals of a pion string associated with the QCD chiral
phase transition in LHC Pb - Pb collision at energy TeV. In
terms of the Kibble-Zurek mechanism we discuss the production and evolution of
the pion string. The pion string is not topologically stable, it decays into
neutral pions and sigma mesons which in turn decay into pions. Our results show
that all the neutral pions from the pion string are distributed at the low
momentum and the ratio of neutral to charged pions from the pion string
violates the isospin symmetry. For the momentum spectra of the total pions, the
signal from the sigma particle decay which is from the pion string will be
affected by the large decay width of the sigma significantly.Comment: 8 pages, 3 figures, one reference added, title changed, version
accepted for publication in Phys. Rev.
Exotic complex Hadamard matrices, and their equivalence
In this paper we use a design theoretical approach to construct new,
previously unknown complex Hadamard matrices. Our methods generalize and extend
the earlier results of de la Harpe--Jones and Munemasa--Watatani and offer a
theoretical explanation for the existence of some sporadic examples of complex
Hadamard matrices in the existing literature. As it is increasingly difficult
to distinguish inequivalent matrices from each other, we propose a new
invariant, the fingerprint of complex Hadamard matrices. As a side result, we
refute a conjecture of Koukouvinos et al. on (n-8)x(n-8) minors of real
Hadamard matrices.Comment: 10 pages. To appear in Cryptography and Communications: Discrete
Structures, Boolean Functions and Sequence
Superconductivity induced by Ni doping in BaFeAs
A series of 122 phase BaFeNiAs ( = 0, 0.055, 0.096, 0.18,
0.23) single crystals were grown by self flux method and a dome-like Ni doping
dependence of superconducting transition temperature is discovered. The
transition temperature reaches a maximum of 20.5 K at = 0.096,
and it drops to below 4 K as 0.23. The negative thermopower in the
normal state indicates that electron-like charge carrier indeed dominates in
this system. This Ni-doped system provides another example of superconductivity
induced by electron doping in the 122 phase.Comment: 7 pages, 5 figures, revised version, added EDX result, accepted for
special issue of NJ
Small doubling in groups
Let A be a subset of a group G = (G,.). We will survey the theory of sets A
with the property that |A.A| <= K|A|, where A.A = {a_1 a_2 : a_1, a_2 in A}.
The case G = (Z,+) is the famous Freiman--Ruzsa theorem.Comment: 23 pages, survey article submitted to Proceedings of the Erdos
Centenary conferenc
Hawking radiation as tunneling and the unified first law of thermodynamics at the apparent horizon in the FRW universe
Relations between the tunneling rate and the unified first law of
thermodynamics at the apparent horizon of the FRW universe are investigated.
The tunneling rate arises as a consequence of the unified first law of
thermodynamics in such a dynamical system. The analysis shows obviously how the
tunneling is intimately connected with the unified first law of thermodynamics
through the principle of conservation of energy.Comment: Latex, 9 pages, no figur
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