2,136 research outputs found
A safe CFT at large charge
We apply the large-charge limit to the first known example of a
four-dimensional gauge-Yukawa theory featuring an ultraviolet interacting fixed
point in all couplings. We determine the energy of the ground state in presence
of large fixed global charges and deduce the global symmetry breaking pattern.
We show that the fermions decouple at low energy leaving behind a confining
Yang-Mills theory and a characteristic spectrum of type I (relativistic) and
type II (non-relativistic) Goldstone bosons. Armed with the knowledge acquired
above we finally arrive at establishing the conformal dimensions of the theory
as a triple expansion in the large-charge, the number of flavors and the
controllably small inverse gauge coupling constant at the UV fixed point. Our
results unveil a number of noteworthy properties of the low-energy spectrum,
vacuum energy and conformal properties of the theory. They also allow us to
derive a new consistency condition for the relative sizes of the couplings at
the fixed point.Comment: 18 pages, published version, some typos correcte
Theoretical performance analysis of the W-ABORT detector
In a recent paper we introduced a modification of the adaptive beaniformer orthogonal rejection test (ABORT) for adaptive detection of signals in unknown noise, by supposing under the null hypothesis the presence of signals orthogonal to the nominal steering vector in the whitened observation space. We will refer to this new receiver as the whitened adaptive beamformer orthogonal rejection test (W-ABORT). Through Monte Carlo simulations this new detector was shown to provide better rejection capabilities of mismatched (e.g., sidelobe) signals than existing ones, like ABORT or the adaptive coherence estimator (ACE), but at the price of a certain loss in terms of detection of matched (i.e., mainlobe) signals. The aim of this paper is to provide a theoretical validation of this fact. We consider both the case of distributed targets and point-like targets. We provide a statistical characterization of the W-ABORT test statistic, under the null hypothesis, and for matched and mismatched signals under the alternative hypothesis. For distributed targets, the probability of false alarm and the probability of detection can only be expressed in terms of multi-dimensional integrals, and are thus very complicated to obtain; in contrast, for point-like targets, such probabilities can be easily calculated by numerical integration techniques. The theoretical expressions derived herein corroborate the simulation results obtained previously
Rapid Serial Visual Presentation. Degradation of inferential reading comprehension as a function of speed
There is increasing interest in the readability of text presented on small digital screens. Designers have come up with novel text presentation methods, such as moving text from right to left, line-stepping, or showing successive text segments such as phrases or single words in a RSVP format. Comparative studies have indicated that RSVP is perhaps the best method of presenting text in a limited space. We tested the method using 209 participants divided into six groups. The groups included traditional reading, and RSVP reading at rates of 250, 300, 350, 400, and 450 wpm. No significant differences were found in comprehension for normal reading and RSVP reading at rates of 250, 300 and 350 wpm. However, higher rates produced significantly lower comprehension scores. It remains to be determined if, with additional practice and improved methods, good levels of reading comprehension at high rates can be achieved with RSV
An improved adaptive sidelobe blanker
We propose a two-stage detector consisting of a subspace
detector followed by the whitened adaptive beamformer orthogonal rejection test. The performance analysis shows that it possesses the constant false alarm rate property with respect to the unknown covariance matrix of the noise and that it can guarantee a wider range of directivity values with respect to previously proposed two-stage detectors. The probability of false alarm and the probability of detection (for both matched and mismatched signals) have been evaluated by means of numerical integration techniques
Does the catechol-O-methyltransferase (COMT) Val158Met human polymorphism in influence procrastination?
Genetic studies are enlightening how the expression of several genes influences neuronal activity and all facets of human normal and abnormal behaviour. Among these, a growing body of information shows that a few key genes regulating activity of central neurotransmitters have specific roles in cognitive and/or emotional processes, as ‘procrastination’. We investigated the association of the 5-HTTLPR and COMT Val158Met polymorphisms with students’ procrastination in an academic writing task. Results: showed no relationship between procrastination and the 5-HTT polymorphism but they revealed an association with the COMT Val158Met one. Particularly, the presence of the Met158 allele was found to be significantly associated with the tendency to initiate
and complete the assigned task. We hypothesize that the role of central monoamines and of dopamine already identified in impulsive behaviour, extends to procrastination. Since the 158Met allele provides neurons with significantly higher basal dopamine levels when compared to the 158Val allele, our observation suggests that under normal conditions the 158Met allele provides carriers with increased inhibitory control, resulting in an increased tendency to adhere to a planned schedule and therefore reducing procrastination. On the other hand, the Val158 allele may result more effective in increasing carriers’ performances under stress conditions, namely when the schedule deadline is approaching, and dopamine release is increased. This would result in a higher tendency to procrastinate. This hypothesis can readily be tested by applying the experimental approach here employed to various samples of subjects belonging to different categories and extending the analysis to other putative neuron-expressed gene
GLRT-Based Direction Detectors in Homogeneous Noise and Subspace Interference
In this paper, we derive and assess decision schemes to discriminate, resorting to an array of sensors, between the H0 hypothesis that data under test contain disturbance only (i.e., noise plus interference) and the H1 hypothesis that they also contain signal components along a direction which is a priori unknown but constrained to belong to a given subspace of the observables. The disturbance is modeled in terms of complex normal random vectors plus deterministic interference assumed to belong to a known subspace. We assume that a set of noise-only (secondary) data is available, which possess the same statistical characterization of noise in the cells under test. At the design stage, we resort to either the plain generalized-likelihood ratio test (GLRT) or the two-step GLRT-based design procedure. The performance analysis, conducted resorting to simulated data, shows that the one-step GLRT performs better than the detector relying on the two-step design procedure when the number of secondary data is comparable to the number of sensors; moreover, it outperforms a one-step GLRT-based subspace detector when the dimension of the signal subspace is sufficiently high
A Preliminar Evidence of Quantum Like Behavior in Measurements of Mental States
Experimental results presented in this paper supports the hypothesis on
quantum-like statistical behaviour of cognitive systems (at least human
beings). Our quantum-like approach gives the possibility to represent mental
states by Hilbert space vectors (complex amplitudes). Such a representation
induces huge reduction of information about a mental state. We realize an
approach that has no direct relation with reductionist quantum models and we
are not interested in statistical behavior of micro systems forming the macro
system of the brain. We describe only probabilistic features of cognitive
measurements. Our quantum-like approach describes statistics of measurements of
cognitive systems with the aim to ascertain if cognitive systems behave as
quantum-like systems where here quantum-like cognitive behavior means that
cognitive systems result to be very sensitive to changes of the context with
regard to the complex of the mental conditions
Ocular-based automatic summarization of documents: is re-reading informative about the importance of a sentence?
Automatic document summarization (ADS) has been introduced as a viable solution for reducing the time and the effort needed to read the ever-increasing textual content that is disseminated. However, a successful universal ADS algorithm has not yet been developed. Also, despite progress in the field, many ADS techniques do not take into account the needs of different readers, providing a summary without internal consistency and the consequent need to re-read the original document. The present study was aimed at investigating the usefulness of using eye tracking for increasing the quality of ADS. The general idea was of that of finding ocular behavioural indicators that could be easily implemented in ADS algorithms. For instance, the time spent in re-reading a sentence might reflect the relative importance of that sentence, thus providing a hint for the selection of text contributing to the summary. We have tested this hypothesis by comparing metrics based on the analysis of eye movements of 30 readers with the highlights they made afterward. Results showed that the time spent reading a sentence was not significantly related to its subjective value, thus frustrating our attempt. Results also showed that the length of a sentence is an unavoidable confounding because longer sentences have both the highest probability of containing units of text judged as important, and receive more fixations and re-fixations
Phenomenology at the LHC of composite particles from strongly interacting Standard Model fermions via four-fermion operators of NJL type
A new physics scenario shows that four-fermion operators of
Nambu-Jona-Lasinio (NJL) type have a strong-coupling UV fixed point, where
composite fermions (bosons ) form as bound states of three (two) SM
elementary fermions and they couple to their constituents via effective contact
interactions at the composite scale (TeV). We
present a phenomenological study to investigate such composite particles at the
LHC by computing the production cross sections and decay widths of composite
fermions in the context of the relevant experiments at the LHC with
collisions at TeV and TeV.
Systematically examining all the different composite particles and the
signatures with which they can manifest, we found a vast spectrum of composite
particles that has not yet been explored at the LHC. Recasting the recent
CMS results of the resonant channel , we find that the composite fermion mass below 4.25 TeV is
excluded for / = 1. We further highlight the region of parameter
space where this specific composite particle can appear using 3 ab,
expected by the High-Luminosity LHC, computing 3 and 5 contour plots
of its statistical significance.Comment: To appear in EPJC. This revised version expands the search for
composite fermion F considering all its possible flavors and topologies and
highlighting the signatures not yet investigated at LH
Charging the Conformal Window
We investigate the properties of near-conformal dynamics in a sector of large
charge when approaching the lower boundary of the conformal window from the
chirally broken phase. To elucidate our approach we use the time-honored
example of the phenomenologically relevant SU(2) color theory featuring
Dirac fermions transforming in the fundamental representation of the gauge
group. In the chirally broken phase we employ the effective pion Lagrangian
featuring also a pseudo-dilaton to capture a possible smooth
conformal-to-non-conformal phase transition. We charge the baryon symmetry of
the Lagrangian and study its impact on the ground state and spectrum of the
theory as well as the would-be conformal dimensions of the lowest large-charge
operator. We moreover study the effects of and dependence on the fermion mass
term.Comment: 15 page
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