scholarly journals Exponentiation in QED and Quasi-Stable Charged Particles

Symmetry ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1389 ◽  
Author(s):  
Stanisław Jadach ◽  
Wiesław Płaczek ◽  
Maciej Skrzypek
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Pair Production ◽  
High Precision ◽  
Functional Form ◽  
Charged Particles ◽  
Soft Photon ◽  
Photon Radiation ◽  
Soft Limit

In this note we present a new exponentiation scheme of soft photon radiation from charged quasi-stable resonances. It generalizes the well established scheme of Yennie, Frautschi and Suura. While keeping the same functional form of an exponent, the new scheme is both exact in its soft limit and accounts properly for the kinematical shift in resonant propagators. We present the scheme on an example of two processes: a toy model of single W production in e ν scattering and the W pair production and decay in e + e − annihilation. The latter process is of relevance for the planned FCCee collider where high precision of Monte Carlo simulations is a primary goal. The proposed scheme is a step in this direction.

scholarly journals Effective Repulsion Between Oppositely Charged Particles in Symmetrical Multivalent Salt Solutions: Effect of Salt Valence

2021 ◽  
Vol 9 ◽  
Author(s):  
Yao Li ◽  
Hai-Long Dong ◽  
Jin-Si Zhang ◽  
Cheng Lin ◽  
Zhi-Jie Tan
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Charged Particles ◽  
Rapid Decrease ◽  
Electrostatic Energy ◽  
Salt Solutions ◽  
Effective Interactions ◽  
Salt Ions ◽  
Translational Entropy ◽  
Oppositely Charged

Salt ions play critical roles in the assembly of polyelectrolytes such as nucleic acids and colloids since ions can regulate the effective interactions between them. In this work, we investigated the effective interactions between oppositely charged particles in symmetrical (z:z) salt solutions by Monte Carlo simulations with salt valence z ranging from 1 to 4. We found that the effective interactions between oppositely charged particles are attractive for 1:1 and low multivalent salts, while they become apparently repulsive for high multivalent salts. Moreover, such effective repulsion becomes stronger as z increases from 2 to 3, while it becomes weaker when z increases from 3 to 4. Our analyses reveal that the overall effective interactions are attributed to the interplay between ion translational entropy and electrostatic energy, and the non-monotonic salt-valence dependence of the effective repulsions is caused by the rapid decrease of attractive electrostatic energy between two oppositely charged particles with their over-condensed counterions of opposite charges when z exceeds 3. Our further MC simulations show that the involvement of local-ranged counterion–co-ion repulsions can enhance the effective repulsions through weakening the attractive electrostatic energy, especially for higher salt valence.

Unreliable Inferences About Unobserved Processes: A Critique of Partial Observability Models

2017 ◽  
Vol 6 (2) ◽  
pp. 381-391
Author(s):  
Carlisle Rainey ◽  
Robert A. Jackson
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Functional Form ◽  
Explanatory Variable ◽  
Partial Observability ◽  
Large Sample ◽  
Sample Bias ◽  
Partially Observable

Methodologists and econometricians advocate the partial observability model as a tool that enables researchers to estimate the distinct effects of a single explanatory variable on two partially observable outcome variables. However, we show that when the explanatory variable of interest influences both partially observable outcomes, the partial observability model estimates are extremely sensitive to misspecification. We use Monte Carlo simulations to show that, under partial observability, minor, unavoidable misspecification of the functional form can lead to substantial large-sample bias, even though the same misspecification leads to little or no bias under full observability.

scholarly journals Azimuthal Correlations of D Mesons with Charged Particles in Simulations with the ALICE Experiment

Particles ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 512-520
Author(s):  
Eszter Frajna ◽  
Robert Vertesi
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
D Mesons ◽  
Charged Particles ◽  
Component Level ◽  
Alice Experiment ◽  
Azimuthal Correlations ◽  
Parton Level ◽  
Correlation Distribution ◽  
Level Analysis

In this work, we present the results of a component-level analysis with Monte Carlo simulations, which aid the interpretation of recent ALICE results of the azimutal correlation distribution of prompt D mesons with charged hadrons in pp and p–Pb collisions at sNN = 5.02 TeV. Parton-level contributions and fragmentation properties are evaluated. Charm and beauty contributions are compared in order to identify the observables that serve as sensitive probes of the production and hadronisation of heavy quarks.

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