scholarly journals The role of colour flows in matrix element computations and Monte Carlo simulations

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Stefano Frixione ◽  
Bryan R. Webber
Keyword(s):  
Monte Carlo ◽  
Matrix Element ◽  
Monte Carlo Simulations ◽  
Closed Form ◽  
Parton Shower ◽  
Natural Generalization ◽  
Tree Level ◽  
Matrix Elements ◽  
Soft Radiation

Abstract We discuss how colour flows can be used to simplify the computation of matrix elements, and in the context of parton shower Monte Carlos with accuracy beyond leading-colour. We show that, by systematically employing them, the results for tree-level matrix elements and their soft limits can be given in a closed form that does not require any colour algebra. The colour flows that we define are a natural generalization of those exploited by existing Monte Carlos; we construct their representations in terms of different but conceptually equivalent quantities, namely colour loops and dipole graphs, and examine how these objects may help to extend the accuracy of Monte Carlos through the inclusion of subleading-colour effects. We show how the results that we obtain can be used, with trivial modifications, in the context of QCD+QED simulations, since we are able to put the gluon and photon soft-radiation patterns on the same footing. We also comment on some peculiar properties of gluon-only colour flows, and their relationships with established results in the mathematics of permutations.

scholarly journals A Coordinated Direct AF/DF Relay-Aided NOMA Framework for Low Outage

2021 ◽  
Author(s):  
Anand Jee ◽  
KAMAL AGRAWAL ◽  
Shankar Prakriya
Keyword(s):  
Energy Efficiency ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Outage Probability ◽  
Closed Form ◽  
Power Allocation ◽  
Multiple Access ◽  
Performance Gain ◽  
Amplify And Forward ◽  
Decode And Forward

This paper investigates the performance of a framework for low-outage downlink non-orthogonal multiple access (NOMA) signalling using a coordinated direct and relay transmission (CDRT) scheme with direct links to both the near-user (NU) and the far-user (FU). Both amplify-and-forward (AF) and decode-and-forward (DF) relaying are considered. In this framework, NU and FU combine the signals from BS and R to attain good outage performance and harness a diversity of two without any need for feedback. For the NU, this serves as an incentive to participate in NOMA signalling. For both NU and FU, expressions for outage probability and throughput are derived in closed form. High-SNR approximations to the outage probability are also presented. We demonstrate that the choice of power allocation coefficient and target rate is crucial to maximize the NU performance while ensuring a desired FU performance. We demonstrate performance gain of the proposed scheme over selective decode-and-forward (SDF) CDRT-NOMA in terms of three metrics: outage probability, sum throughput and energy efficiency. Further, we demonstrate that by choosing the target rate intelligently, the proposed CDRT NOMA scheme ensures higher energy efficiency (EE) in comparison to its orthogonal multiple access counterpart. Monte Carlo simulations validate the derived expressions.

Self-assembly of conformationally flexible molecules under 2D confinement: structural analysis from computer simulations

2018 ◽  
Vol 54 (63) ◽  
pp. 8749-8752 ◽  
Author(s):  
Damian Nieckarz ◽  
Paweł Szabelski
Keyword(s):  
Monte Carlo ◽  
Structural Analysis ◽  
Monte Carlo Simulations ◽  
Computer Simulations ◽  
Self Assembly ◽  
Flexible Molecules

Monte Carlo simulations reveal the role of surface conformers in self-assembly on crystalline supports.

scholarly journals An event generator for same-sign W-boson scattering at the LHC including electroweak corrections

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Mauro Chiesa ◽  
Ansgar Denner ◽  
Jean-Nicolas Lang ◽  
Mathieu Pellen
Keyword(s):  
Monte Carlo ◽  
Matrix Element ◽  
Parton Shower ◽  
W Boson ◽  
Event Generator ◽  
Monte Carlo Program ◽  
The Matrix ◽  
Electroweak Corrections

Abstract In this article we present an event generator based on the Monte Carlo program Powheg in combination with the matrix-element generator Recola. We apply it to compute NLO electroweak corrections to same-sign W-boson scattering, which have been shown to be large at the LHC. The event generator allows for the generation of unweighted events including the effect of the NLO electroweak corrections matched to a QED parton shower and interfaced to a QCD parton shower. In view of the expected experimental precision of future measurements, the use of such a tool will be indispensable.

A Markov-Chain-Based Model for Group Message Distribution in Connected Networks

2020 ◽  
Vol 1 (2) ◽  
pp. 13-29
Author(s):  
Peter Bajorski ◽  
Michael Kurdziel
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Monte Carlo Simulations ◽  
Closed Form ◽  
Spanning Tree ◽  
Closed Form Expression ◽  
Form Expression ◽  
Distribution Process ◽  
Computationally Intensive ◽  
Group 2

The authors introduce a stochastic Markov-chain-based model for the recursive distribution of a message from the source node to all remaining nodes. This recursive message distribution process produces a spanning tree topology over the connected network of nodes. The model has five input parameters: (1) the number of nodes n in the group, (2) the maximum number of child nodes, (3) the number of sub-message components needed to transfer a single message, (4) the probability p1 that two adjacent nodes in a network initiate a connection (edge) in the spanning tree, and (5) the probability p2 that each sub-message component is transferred correctly between nodes. The authors derive a closed-form expression for the expected group message distribution time, measured in discrete-time epochs, that is verified via Monte Carlo simulations. Since both the closed-form formulas and the Monte Carlo simulations are computationally intensive for networks with a large number of nodes n, this paper derives a reliable approximate formula for the expected distribution time for networks as large as n = 1000.

scholarly journals Diffusion of oxygen interstitials in UO2+ using kinetic Monte Carlo simulations: Role of O/M ratio and sensitivity analysis

2016 ◽  
Vol 472 ◽  
pp. 89-98 ◽  
Author(s):  
Rakesh K. Behera ◽  
Taku Watanabe ◽  
David A. Andersson ◽  
Blas P. Uberuaga ◽  
Chaitanya S. Deo
Keyword(s):  
Sensitivity Analysis ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Kinetic Monte Carlo ◽  
Kinetic Monte Carlo Simulations

scholarly journals Role of winding numbers in quantum Monte Carlo simulations

1998 ◽  
Vol 57 (21) ◽  
pp. 13382-13385 ◽  
Author(s):  
Patrik Henelius ◽  
S. M. Girvin ◽  
Anders W. Sandvik
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Quantum Monte Carlo ◽  
Quantum Monte Carlo Simulations

scholarly journals A Coordinated Direct AF/DF Relay-Aided NOMA Framework for Low Outage

2021 ◽  
Author(s):  
Anand Jee ◽  
KAMAL AGRAWAL ◽  
Shankar Prakriya
Keyword(s):  
Energy Efficiency ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Outage Probability ◽  
Closed Form ◽  
Power Allocation ◽  
Multiple Access ◽  
Performance Gain ◽  
Amplify And Forward ◽  
Decode And Forward

This paper investigates the performance of a framework for low-outage downlink non-orthogonal multiple access (NOMA) signalling using a coordinated direct and relay transmission (CDRT) scheme with direct links to both the near-user (NU) and the far-user (FU). Both amplify-and-forward (AF) and decode-and-forward (DF) relaying are considered. In this framework, NU and FU combine the signals from BS and R to attain good outage performance and harness a diversity of two without any need for feedback. For the NU, this serves as an incentive to participate in NOMA signalling. For both NU and FU, expressions for outage probability and throughput are derived in closed form. High-SNR approximations to the outage probability are also presented. We demonstrate that the choice of power allocation coefficient and target rate is crucial to maximize the NU performance while ensuring a desired FU performance. We demonstrate performance gain of the proposed scheme over selective decode-and-forward (SDF) CDRT-NOMA in terms of three metrics: outage probability, sum throughput and energy efficiency. Further, we demonstrate that by choosing the target rate intelligently, the proposed CDRT NOMA scheme ensures higher energy efficiency (EE) in comparison to its orthogonal multiple access counterpart. Monte Carlo simulations validate the derived expressions.

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