A sampling algorithm to estimate the effect of fluctuations in particle physics data

Background properties in experimental particle physics are typically estimated using large data sets. However, different events can exhibit different features because of the quantum mechanical nature of the underlying physics processes. While signal and background fractions in a given data set can be evaluated using a maximum likelihood estimator, the shapes of the corresponding distributions are traditionally obtained using high-statistics control samples, which normally neglects the effect of fluctuations. On the other hand, if it was possible to subtract background using templates that take fluctuations into account, this would be expected to improve the resolution of the observables of interest, and to reduce systematics depending on the analysis. This study is an initial step in this direction. We propose a novel algorithm inspired by the Gibbs sampler that makes it possible to estimate the shapes of signal and background probability density functions from a given collection of particles, using control sample templates as initial conditions and refining them to take into account the effect of fluctuations. Results on Monte Carlo data are presented, and the prospects for future development are discussed.Comment: 6 pages, 1 figure. Edited to improve readability in line with the published article. This is based on a condensed version for publication in the Proceedings of the International Conference on Mathematical Modelling in the Physical Sciences, IC-MSQUARE 2012, Budapest, Hungary. A more detailed discussion can be found in the preceding version of this arXiv recor

Toward particle-level filtering of individual collision events at the Large Hadron Collider and beyond

Low-energy strong interactions are a major source of background at hadron colliders, and methods of subtracting the associated energy flow are well established in the field. Traditional approaches treat the contamination as diffuse, and estimate background energy levels either by averaging over large data sets or by restricting to given kinematic regions inside individual collision events. On the other hand, more recent techniques take into account the discrete nature of background, most notably by exploiting the presence of substructure inside hard jets, i.e. inside collections of particles originating from scattered hard quarks and gluons. However, none of the existing methods subtract background at the level of individual particles inside events. We illustrate the use of an algorithm that will allow particle-by-particle background discrimination at the Large Hadron Collider, and we envisage this as the basis for a novel event filtering procedure upstream of the official reconstruction chains. Our hope is that this new technique will improve physics analysis when used in combination with state-of-the-art algorithms in high-luminosity hadron collider environments

On the frequency distribution of neutral particles from low-energy strong interactions

Copyright © 2017 Federico Colecchia and Akram Khan. The rejection of the contamination, or background, from low-energy strong interactions at hadron collider experiments is a topic that has received significant attention in the field of particle physics. This article builds on a particle-level view of collision events, in line with recently-proposed subtraction methods. While conventional techniques in the field usually concentrate on probability distributions, our study is, to our knowledge, the first attempt at estimating the frequency distribution of background particles across the kinematic space inside individual collision events. In fact, while the probability distribution can generally be estimated given a model of low-energy strong interactions, the corresponding frequency distribution inside a single event typically deviates from the average and cannot be predicted a priori. We present preliminary results in this direction, and establish a connection between our technique and the particle weighting methods that have been the subject of recent investigation at the Large Hadron Collider

Toward the estimation of background fluctuations under newly-observed signals in particle physics

When the number of events associated with a signal process is estimated in particle physics, it is common practice to extrapolate background distributions from control regions to a predefined signal window. This allows accurate estimation of the expected, or average, number of background events under the signal. However, in general, the actual number of background events can deviate from the average due to fluctuations in the data. Such a difference can be sizable when compared to the number of signal events in the early stages of data analysis following the observation of a new particle, as well as in the analysis of rare decay channels. We report on the development of a data-driven technique that aims to estimate the actual, as opposed to the expected, number of background events in a predefined signal window. We discuss results on toy Monte Carlo data and provide a preliminary estimate of systematic uncertainty

Pricing of Islamic Banking and Conventional Banking: An Empirical Study

This paper examines and assesses the extent to which pricing of Islamic banking and finance (IBF) worldwide is correlated to conventional finance. The data used were obtained from the Islamic Finance Country Index (IFCI) and the Cbonds platform. The IFCI is a methodology developed by Edbiz Consulting to measure the growth of IBF. The IFCI has been gathering data for nine years, sufficient time to yield meaningful results. Cbonds is a financial-data vendor highly specialised in the analysis of bond markets. This study provides both a qualitative analysis in the form of a tile map chart and a statistical test aimed at generalising the correlation between IBF expansion and interest rates to all countries where IBF banks might locate. This correlation is estimated by dividing the analysed countries into tertiles according to their interest rate and comparing the mean IFCI scores. The difference between the lowest tertile and the others is statistically significant. This appears to be the first empirical study to incorporate the whole geographical scope of the IFCI and analyse the interest rates of all countries to which IBF expansion metrics apply. Emerging markets represent an important growth opportunity for Islamic banks. In fact, the presence of Zakat as a mandatory tax to reduce poverty and the idea of a system based on distribution of wealth are important factors for developing economies. This study is consistent with previous findings: the IBF pricing system is correlated to the conventional banking system, and there is a positive correlation between the IFCI and countries with high yields. The main limitation of this study is the difficulty in obtaining the 10-yearyield to maturity (YTM) of countries for which no data was available

Il territorio raccontato: la valorizzazione dei ‘luoghi’ di Ignazio Silone come elemento propulsivo di circuiti geoturistici autosostenibili

Literary routes inspired by landscapes can become key elements for a self-sustainable development, they illuminating the collective memory, encouraging grassroots processes of self-organisation, and highlighting the relationships between the growth of place consciousness and the enhancement of local patrimonial resources. A significant experience is “Sentiero Silone”, an excursionist itinerary created in the Sirente-Velino Park in 2015, which links the places described by Ignazio Silone and identified through oral interviews with local communities. Silone’s writings give the elements of landscape with symbolic connotations and social meanings, allowing for a dynamic approach to the economic and social-cultural reality of the past; they integrate written sources, archaeological evidences and environmental indicators outlining the various landscapes in their historical depth. and allowing visitors to build a tangible sensorial experience in situ following the author’s life and his novels’ plots. In the Park sustainable tourism and a holistic reading of territories are expressed in various thematic itineraries with the possibility of intersections, to offer a global overview of how an environment can turn into a territory. Literary representation is one of the guidelines to review and interpret landscapes, in order to define the relationships between the past and the present and to propose future scenarios apt to integrate research, innovation and sustainability

Data-driven estimation of neutral pileup particle multiplicity in high-luminosity hadron collider environments

The upcoming operation regimes of the Large Hadron Collider are going to place stronger requirements on the rejection of particles originating from pileup, i.e. from interactions between other protons. For this reason, particle weighting techniques have recently been proposed in order to subtract pileup at the level of individual particles. We describe a choice of weights that, unlike others that rely on particle proximity, exploits the particle-level kinematic signatures of the high-energy scattering and of the pileup interactions. We illustrate the use of the weights to estimate the number density of neutral pileup particles inside individual events, and we elaborate on the complementarity between ours and other methods. We conclude by suggesting the idea of combining different sets of weights with a view to exploiting different features of the underlying processes for improved pileup subtraction at higher luminosity.High Energy Physics Group at Brunel University Londo

Predictive factors for hepatocellular carcinoma recurrence after curative treatments

Hepatocellular carcinoma (HCC) is the fifth most common neoplasm worldwide. Recurrence of HCC after resection or loco-regional therapies represents an important clinical issue as it affects up to 70% of patients. This can be divided into early or late, if it occurs within or after 24 months after treatment, respectively. While the predictive factors for early recurrence are mainly related to tumour biology (local invasion and intrahepatic metastases), late recurrences are mainly related to de novo tumour formation. Thus, it is important to recognize these factors prior to any treatment in each patient, in order to optimize the treatment strategy and follow-up after treatment. The aim of this review is to summarize the current evidence available regarding predictive factors for the recurrence of HCC, according to the different therapeutic strategies available. In particular, we will discuss the role of new ultrasound-based techniques and biological features, such as tumor-related and circulating biomarkers, in predicting HCC recurrence. Recent advances in imaging-related parameters in computed-tomography scans and magnetic resonance imaging will also be discussed