scholarly journals Precise predictions for photon pair production matched to parton showers in GENEVA

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Simone Alioli ◽  
Alessandro Broggio ◽  
Alessandro Gavardi ◽  
Stefan Kallweit ◽  
Matthew A. Lim ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Pair Production ◽  
Higher Order ◽  
Photon Pair ◽  
Effective Theory ◽  
Parton Level ◽  
Soft Collinear Effective Theory ◽  
Additional Radiation ◽  
Monte Carlo Framework ◽  
Good Agreement

Abstract We present a new calculation for the production of isolated photon pairs at the LHC with $$ {\mathrm{NNLL}}_{{\mathcal{T}}_0}^{\prime } $$ NNLL T 0 ′ +NNLO accuracy. This is the first implementation within the Geneva Monte Carlo framework of a process with a nontrivial Born-level definition which suffers from QED singularities. Throughout the computation we use a smooth-cone isolation algorithm to remove such divergences. The higher-order resummation of the 0-jettiness resolution variable $$ {\mathcal{T}}_0 $$ T 0 is based on a factorisation formula derived within Soft-Collinear Effective Theory which predicts all of the singular, virtual and real NNLO corrections. Starting from this precise parton-level prediction and by employing the Geneva method, we provide fully showered and hadronised events using Pythia8, while retaining the NNLO QCD accuracy for observables which are inclusive over the additional radiation. We compare our final predictions to LHC data at 7 TeV and find good agreement.

scholarly journals RECENT PROGRESS IN QCD FACTORIZATION FOR B → M1M2

2008 ◽  
Vol 23 (21) ◽  
pp. 3255-3258
Author(s):  
DESHAN YANG
Keyword(s):  
Recent Progress ◽  
Higher Order ◽  
Effective Theory ◽  
Radiative Corrections ◽  
Qcd Factorization ◽  
Soft Collinear Effective Theory

After briefly introducing the framework of QCD factorization for B → M1M2 in the language of the Soft-Collinear Effective Theory, we firstly address the recent efforts on higher-order radiative corrections in QCD factorization. Then we discuss some phenomenologies in B → VV within the framework of QCD factorization.

J/ψ PRODUCTION IN A GLAUBER MONTE CARLO FRAMEWORK

2010 ◽  
Vol 25 (05) ◽  
pp. 1009-1018 ◽  
Author(s):  
HONG-MIN WANG ◽  
ZHAO-YU HOU ◽  
BEN-AI ZHANG ◽  
XIAN-JING SUN
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Center Of Mass ◽  
Nuclear Modification Factor ◽  
Center Of Mass Energy ◽  
Modification Factor ◽  
Energy Formula ◽  
Theoretical Results ◽  
Monte Carlo Framework ◽  
Good Agreement

By means of a Glauber Monte Carlo framework, the J/ψ production at RHIC energies is studied with the EKS98, EPS09 and HKN07 shadowing parameters. With a χ2 analysis of the experimental data given by PHENIX, a significant dependence of the absorption cross-section, σ abs , on the J/ψ-nucleon center-of-mass energy, [Formula: see text], is revealed with the HKN07 shadowing, but an unconspicuous dependence is shown with the EKS98 and EPS09 shadowing. In this paper, the nuclear modification factor Rd Au vs y, pT and N coll are also calculated and the theoretical results are in good agreement with the experimental data.

scholarly journals Resummation of Jet Shapes and Extracting Properties of the Quark-Gluon Plasma

2015 ◽  
Vol 37 ◽  
pp. 1560047 ◽  
Author(s):  
Yang-Ting Chien
Keyword(s):  
Quark Gluon Plasma ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Jet Quenching ◽  
Effective Theory ◽  
Proton Proton ◽  
Power Corrections ◽  
Soft Collinear Effective Theory ◽  
Jet Shapes ◽  
Good Agreement

Understanding the properties of the quark-gluon plasma (QGP) that is produced in ultra-relativistic nucleus-nucleus collisions has been one of the top priorities of the heavy ion program at the LHC. Energetic jets are produced and subsequently quenched in the collisions. Such jet quenching phenomena provide promising tools to probe the medium properties by studying the modification of jets due to the medium interactions. Significant modifications of jet shapes have been measured. In this talk we focus on the calculation of jet shapes in both proton-proton and lead-lead collisions using soft-collinear effective theory (SCET), with Glauber gluon interactions in the medium. Large logarithms in jet shapes are resummed at next-to-leading logarithmic (NLL) accuracy by the renormalization-group evolution between hierarchical jet scales. The medium interactions contribute as power corrections, and we calculate the modification of jet shapes at leading order in opacity with the static QGP model. Preliminary results are presented with good agreement with the recent CMS jet shape measurements.

scholarly journals Cutoff dependence of the thrust peak position in the dipole shower

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Robin Baumeister ◽  
Stefan Weinzierl
Keyword(s):  
Parton Shower ◽  
Peak Position ◽  
Effective Theory ◽  
Cutoff Value ◽  
Soft Collinear Effective Theory ◽  
Thrust Distribution ◽  
Cutoff Dependence ◽  
Analytic Computation ◽  
Good Agreement

AbstractWe analyse the dependence of the peak position of the thrust distribution on the cutoff value in the Nagy–Soper dipole shower. We compare the outcome of the parton shower simulations to a relation of the dependence from an analytic computation, derived within soft-collinear effective theory. We show that the result of the parton shower simulations and the analytic computation are in good agreement.

scholarly journals NEAR-THRESHOLD Z-PAIR PRODUCTION IN THE MODEL OF UNSTABLE PARTICLES WITH SMEARED MASS

2008 ◽  
Vol 23 (25) ◽  
pp. 4125-4132 ◽  
Author(s):  
V. I. KUKSA ◽  
R. S. PASECHNIK
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Pair Production ◽  
Suggested Approach ◽  
Unstable Particles ◽  
Good Agreement ◽  
Near Threshold

Near-threshold production of neutral boson pairs is considered within the framework of the model of unstable particles with smeared mass. The results of calculations are in good agreement with LEP II data and Monte Carlo simulations. Suggested approach significantly simplifies calculations with respect to standard perturbative one.

scholarly journals NEAR-THRESHOLD W-PAIR PRODUCTION IN THE MODEL OF UNSTABLE PARTICLES WITH SMEARED MASS

2009 ◽  
Vol 24 (31) ◽  
pp. 5765-5777 ◽  
Author(s):  
V. I. KUKSA ◽  
R. S. PASECHNIK
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Pair Production ◽  
Suggested Approach ◽  
Unstable Particles ◽  
Charged Boson ◽  
Good Agreement ◽  
Near Threshold

Near-threshold production of charged boson pairs is considered within the framework of the model of unstable particles with smeared mass. The results of calculations are in good agreement with LEP II data and Monte Carlo simulations. Suggested approach significantly simplifies calculations with respect to standard perturbative one.

scholarly journals Mitigating Large Background in Jet Substructure Observables

2020 ◽  
Vol 235 ◽  
pp. 05002
Author(s):  
Daekyoung Kang ◽  
Yang-Ting Chien ◽  
Kyle Lee ◽  
Yiannis Makris
Keyword(s):  
Jet Physics ◽  
Effective Theory ◽  
Soft Particle ◽  
Jet Substructure ◽  
Mass Measurements ◽  
New Approach ◽  
Soft Collinear Effective Theory ◽  
Pile Up ◽  
Theoretical Results ◽  
Good Agreement

We discuss a new approach for jet physics analysis by using subtraction between cumulants of jet substructure observables. The subtracted cumulants are insensitive to soft-particle background uncorrelated with the hard process and allow comparisons between theoretical results and experimental measurements without the complication of soft background like underlying and pile-up events. We find our method using jet mass cumulants efficiently eliminates the background in Monte Carlo simulations and ATLAS jet mass measurements and they show a good agreement with our analytic calculations performed using soft-collinear effective theory.

Effective Field Theory in Particle Physics and Cosmology

2020 ◽  
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Particle Physics ◽  
Large Scale ◽  
Effective Field ◽  
Effective Theory ◽  
Soft Collinear Effective Theory ◽  
Multiple Length Scales ◽  
Cosmological Observations ◽  
Standard Models

Effective field theory (EFT) is a general method for describing quantum systems with multiple-length scales in a tractable fashion. It allows us to perform precise calculations in established models (such as the standard models of particle physics and cosmology), as well as to concisely parametrize possible effects from physics beyond the standard models. EFTs have become key tools in the theoretical analysis of particle physics experiments and cosmological observations, despite being absent from many textbooks. This volume aims to provide a comprehensive introduction to many of the EFTs in use today, and covers topics that include large-scale structure, WIMPs, dark matter, heavy quark effective theory, flavour physics, soft-collinear effective theory, and more.

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