arXiv subjects

Nicholas Carrara

Publications and source records attributed to Nicholas Carrara.

8 recordsLinked to original sources

arXiv2023

Visualization and Efficient Generation of Constrained High-dimensional Theoretical Parameter Spaces

We describe a set of novel methods for efficiently sampling high-dimensional parameter spaces of physical theories defined at high energies, but constrained by experimental measurements made at lower energies. Often, theoretical models such as supersymmetry are defined by many parameters, $\mathcal{O}(10-100)$, expressed at high energies, while relevant experimental constraints are often defined at much lower energies, preventing them from directly ruling out portions of the space. Instead, the low-energy constraints define a complex, potentially non-contiguous subspace of the theory parameters. Naive scanning of the theory space for points which satisfy the low-energy constraints is hopelessly inefficient due to the high dimensionality, and the inverse problem is considered intractable. As a result, many theoretical spaces remain under-explored. We introduce a class of modified generative autoencoders, which attack this problem by mapping the high-dimensional parameter space to a structured low-dimensional latent space, allowing for easy visualization and efficient generation of theory points which satisfy experimental constraints. An extension without dimensional compression, which focuses on limiting potential information loss, is also introduced.

hep-ph↗

arXiv2022

The Inference Framework

The following three sections and appendices are taken from my thesis "The Foundations of Inference and its Application to Fundamental Physics" from 2021, in which I construct a theory of entropic inference from first principles. The majority of these chapters are not original, but are a collection of various sources through the history of the subject. The first section deals with deductive reasoning, which is inference in the presence of complete information. The second section expands on the deductive system by constructing a theory of inductive inference, a theory of probabilities, which is inference in the presence of incomplete information. Finally, section three develops a means of updating these probabilities in the presence of new information that comes in the form of constraints.

stat.OT↗

arXiv2021

The Entropic Dynamics of Spin

In the Entropic Dynamics (ED) approach the essence of quantum theory lies in its probabilistic nature while the Hilbert space structure plays a secondary and ultimately optional role. The dynamics of probability distributions is driven by the maximization of an entropy subject to constraints that carry the relevant physical information -- directionality, correlations, gauge interactions, etc. The challenge is to identify those constraints and to establish a criterion for how the constraints themselves are updated. In this paper the ED framework is extended to describe a spin-1/2 point particle. In ED spin is neither modelled as a rotating body, nor through the motion of a point particle; it is an epistemic property of the wave function. The constraint that reflects the peculiar rotational properties of spin is most effectively expressed in the language of geometric algebra. The updating of all constraints is carried out in a way that stresses the central importance of symmetry principles. First we identify the appropriate symplectic and metric structures in the phase space of probabilities, their conjugate momenta, and the spin variables. This construction yields a derivation of the Fubini-Study metric for a spin-1/2 particle which highlights its deep connection to information geometry. Then we construct an ED that preserves both the symplectic structure (a Hamiltonian flow) and the metric structure (a Killing flow). We show that generic Hamiltonian-Killing flows are linear in the wave function. Imposing further that the Hamiltonian be the generator of an entropic evolution in time leads to an entropic dynamics described by the Pauli equation. We conclude with a discussion of the new interpretation of the formalism which yields a physical picture that is significantly different from that provided by other interpretations.

quant-ph↗

arXiv2020

The Design of Global Correlation Quantifiers and Continuous Notions of Statistical Sufficiency

Using first principles from inference, we design a set of functionals for the purposes of \textit{ranking} joint probability distributions with respect to their correlations. Starting with a general functional, we impose its desired behaviour through the \textit{Principle of Constant Correlations} (PCC), which constrains the correlation functional to behave in a consistent way under statistically independent inferential transformations. The PCC guides us in choosing the appropriate design criteria for constructing the desired functionals. Since the derivations depend on a choice of partitioning the variable space into $n$ disjoint subspaces, the general functional we design is the $n$-partite information (NPI), of which the \textit{total correlation} and \textit{mutual information} are special cases. Thus, these functionals are found to be uniquely capable of determining whether a certain class of inferential transformations, $ρ\xrightarrow{*}ρ'$, preserve, destroy or create correlations. This provides conceptual clarity by ruling out other possible global correlation quantifiers. Finally, the derivation and results allow us to quantify non-binary notions of statistical sufficency. Our results express what percentage of the correlations are preserved under a given inferential transformation or variable mapping.

cs.IT↗

arXiv2019

On the Estimation of Mutual Information

In this paper we focus on the estimation of mutual information from finite samples $(\mathcal{X}\times\mathcal{Y})$. The main concern with estimations of mutual information is their robustness under the class of transformations for which it remains invariant: i.e. type I (coordinate transformations), III (marginalizations) and special cases of type IV (embeddings, products). Estimators which fail to meet these standards are not \textit{robust} in their general applicability. Since most machine learning tasks employ transformations which belong to the classes referenced in part I, the mutual information can tell us which transformations are most optimal\cite{Carrara_Ernst}. There are several classes of estimation methods in the literature, such as non-parametric estimators like the one developed by Kraskov et. al\cite{KSG}, and its improved versions\cite{LNC}. These estimators are extremely useful, since they rely only on the geometry of the underlying sample, and circumvent estimating the probability distribution itself. We explore the robustness of this family of estimators in the context of our design criteria.

physics.data-an↗

arXiv2019

Quantum Trajectories in Entropic Dynamics

Entropic Dynamics is a framework for deriving the laws of physics from entropic inference. In an (ED) of particles, the central assumption is that particles have definite yet unknown positions. By appealing to certain symmetries, one can derive a quantum mechanics of scalar particles and particles with spin, in which the trajectories of the particles are given by a stochastic equation. This is much like Nelson's stochastic mechanics which also assumes a fluctuating particle as the basis of the microstates. The uniqueness of ED as an entropic inference of particles allows one to continuously transition between fluctuating particles and the smooth trajectories assumed in Bohmian mechanics. In this work we explore the consequences of the ED framework by studying the trajectories of particles in the continuum between stochastic and Bohmian limits in the context of a few physical examples, which include the double slit and Stern-Gerlach experiments.

quant-ph↗

arXiv2018

Quantum phases in entropic dynamics

In the Entropic Dynamics framework the dynamics is driven by maximizing entropy subject to appropriate constraints. In this work we bring Entropic Dynamics one step closer to full equivalence with quantum theory by identifying constraints that lead to wave functions that remain single-valued even for multi-valued phases by recognizing the intimate relation between quantum phases, gauge symmetry, and charge quantization.

quant-ph↗

arXiv2017

On the Upper Limit of Separability

We propose an approach to rapidly find the upper limit of separability between datasets that is directly applicable to HEP classification problems. The most common HEP classification task is to use $n$ values (variables) for an object (event) to estimate the probability that it is signal vs. background. Most techniques first use known samples to identify differences in how signal and background events are distributed throughout the $n$-dimensional variable space, then use those differences to classify events of unknown type. Qualitatively, the greater the differences, the more effectively one can classify events of unknown type. We will show that the Mutual Information (MI) between the $n$-dimensional signal-background mixed distribution and the answers for the known events, tells us the upper-limit of separation for that set of $n$ variables. We will then compare that value to the Jensen-Shannon Divergence between the output distributions from a classifier to test whether it has extracted all possible information from the input variables. We will also discuss speed improvements to a standard method for calculating MI. Our approach will allow one to: a) quickly measure the maximum possible effectiveness of a large number of potential discriminating variables independent of any specific classification algorithm, b) identify potential discriminating variables that are redundant, and c) determine whether a classification algorithm has achieved the maximum possible separation. We test these claims first on simple distributions and then on Monte Carlo samples generated for Supersymmetry and Higgs searches. In all cases, we were able to a) predict the separation that a classification algorithm would reach, b) identify variables that carried no additional discriminating power, and c) identify whether an algorithm had reached the optimum separation. Our code is publicly available.

hep-ex↗