678 research outputs found
Critical-point anomalies in doped CeRhIn5
The heavy-fermion compound CeRhIn can be tuned through a quantum critical
point, when In is partially replaced by Sn. This way additional charge carriers
are introduced and the antiferromagnetic order is gradually suppressed to zero
temperature. Here we investigate the temperature-dependent optical properties
of CeRh(InSn) single crystals for , and
. With increasing Sn concentration the infrared conductivity reveals a
clear enhancement of the - hybridization strength. At low temperatures we
observed a non-Fermi-liquid behavior in the frequency dependence of the
scattering rate and effective mass in all three compounds. In addition, below a
characteristic temperature K, the temperature dependent
resistivity follows a behavior, typical for a non-Fermi
liquid. The temperature-dependent magnetization also exhibits anomalous
behavior below . Our investigation reveal that below the system
shows a pronounced non-Fermi-liquid behavior and monotonically increases
as the quantum critical point is approached
Novel methods for anomaly detection
Anomaly detection is of increasing importance in the data rich world of today. It can be applied to a broad range of challenges ranging from fault detection to fraud prevention and cyber-security. Many of these application require algorithms which are very scalable, as well as accurate, due to large data volumes and/or limited computational resources. This thesis contributes three novel approaches to the field of anomaly detection. The first contribution, Collective And Point Anomalies (CAPA) detects and distinguishes between both collective and point anomalies in linear time. The second contribution, MultiVariate Collective And Point Anomalies (MVCAPA) extends CAPA to the multivariate setting. The third contribution is a novel particle based kalman filter which detects and distinguished between additive outliers and innovative outliers
Chiral fermions and anomaly cancellation on orbifolds with Wilson lines and flux
We consider six-dimensional supergravity compactified on orbifolds with
Wilson lines and bulk flux. Torus Wilson lines are decomposed into Wilson lines
around the orbifold fixed points, and twisted boundary conditions of matter
fields are related to fractional localized flux. Both, orbifold singularities
and flux lead to chiral fermions in four dimensions. We show that in addition
to the standard bulk and fixed point anomalies the Green-Schwarz term also
cancels the four-dimensional anomaly induced by the flux background. The two
axions contained in the antisymmetric tensor field both contribute to the
cancellation of the four-dimensional anomaly and the generation of a vector
boson mass via the Stueckelberg mechanism. An orthogonal linear combination of
the axions remains massless and couples to the gauge field in the standard way.
Furthermore, we construct convenient expressions for the wave functions of the
zero modes and relate their multiplicity and behavior at the fixed points to
the bulk flux quanta and the Wilson lines.Comment: 30 pages, 4 figures, 1 table, clarifying remarks adde
TeV scale 5D unification and the fixed point anomaly cancellation with chiral split multiplets
A possibility of 5D gauge unification of in
is examined. The orbifold compactification allows fixed points where
representations can be assigned. We present a few
possibilities which give long proton lifetime, top-bottom mass hierarchy from
geometry, and reasonable neutrino masses. In general, these {\it chiral models}
can lead to fixed point anomalies. We can show easily, due to the simplicity of
the model, that these anomalies are cancelled by the relevant Chern-Simons
terms for all the models we consider. It is also shown that the fixed point
U(1)--graviton--graviton anomaly cancels without the help from the Chern-Simons
term. Hence, we conjecture that the fixed point anomalies can be cancelled if
the effective 4D theory is made anomaly free by locating chiral fermions at the
fixed points.Comment: LaTeX file of 19 pages with 1 figur
Nominality Score Conditioned Time Series Anomaly Detection by Point/Sequential Reconstruction
Time series anomaly detection is challenging due to the complexity and
variety of patterns that can occur. One major difficulty arises from modeling
time-dependent relationships to find contextual anomalies while maintaining
detection accuracy for point anomalies. In this paper, we propose a framework
for unsupervised time series anomaly detection that utilizes point-based and
sequence-based reconstruction models. The point-based model attempts to
quantify point anomalies, and the sequence-based model attempts to quantify
both point and contextual anomalies. Under the formulation that the observed
time point is a two-stage deviated value from a nominal time point, we
introduce a nominality score calculated from the ratio of a combined value of
the reconstruction errors. We derive an induced anomaly score by further
integrating the nominality score and anomaly score, then theoretically prove
the superiority of the induced anomaly score over the original anomaly score
under certain conditions. Extensive studies conducted on several public
datasets show that the proposed framework outperforms most state-of-the-art
baselines for time series anomaly detection.Comment: NeurIPS 2023 (https://neurips.cc/virtual/2023/poster/70582
Critical Point Anomalies Include Expansion Shock Waves
From first-principle fluid dynamics, complemented by a rigorous state equation accounting for critical anomalies, we discovered that expansion shock waves may occur in the vicinity of the liquid-vapor critical point in the two-phase region. Due to universality of near-critical thermodynamics, the result is valid for any common pure fluid in which molecular interactions are only short-range, namely, for so-called 3-dimensional Ising-like systems, and under the assumption of thermodynamic equilibrium. In addition to rarefaction shock waves, diverse non-classical effects are admissible, including composite compressive shock-fan-shock waves, due to the change of sign of the fundamental derivative of gasdynamics
- …