Predictions for Boson-jet Observables and Fragmentation Function Ratios from a Hybrid Strong/weak Coupling Model for Jet Quenching

Predictions for Boson-jet Observables and Fragmentation Function Ratios from a Hybrid Strong/weak Coupling Model for Jet Quenching

Author:

Publisher:

Published: 2016

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

We have previously introduced a hybrid strong/weak coupling model for jet quenching in heavy ion collisions in which we describe the production and fragmentation of jets at weak coupling, using Pythia, and describe the rate at which each parton in the jet shower loses energy as it propagates through the strongly coupled plasma, dE/dx, using an expression computed holographically at strong coupling. The model has a single free parameter that we fit to a single experimental measurement. We then confront our model with experimental data on many other jet observables, focusing in this paper on boson-jet observables, finding that it provides a good description of present jet data. Next, we provide the predictions of our hybrid model for many measurements to come, including those for inclusive jet, dijet, photon-jet and Z-jet observables in heavy ion collisions with energy √s = 5 : 02 ATeV coming soon at the LHC. As the statistical uncertainties on near-future measurements of photon-jet observables are expected to be much smaller than those in present data, with about an order of magnitude more photon-jet events expected, predictions for these observables are particularly important. We find that most of our pre- and post-dictions do not depend sensitively on the form we choose for the rate of energy loss dE/dx of the partons in the shower. This gives our predictions considerable robustness. To better discriminate between possible forms for the rate of energy loss, though, we must turn to intrajet observables. Here, we focus on ratios of fragmentation functions. Finally, we close with a suggestion for a particular ratio, between the fragmentation functions of inclusive and associated jets with the same kinematics in the same collisions, which is particularly sensitive to the x- and E-dependence of dE/dx, and hence may be used to learn which mechanism of parton energy loss best describes the quenching of jets.


Modified Fragmentation Function and Jet Quenching at RHIC.

Modified Fragmentation Function and Jet Quenching at RHIC.

Author:

Publisher:

Published: 2001

Total Pages: 5

ISBN-13:

DOWNLOAD EBOOK

Medium modification of jet fragmentation functions and parton energy loss in cold and hot matter are reviewed. The predicted nuclear modification of the jet fragmentation function agrees well with the recent HERMES data with a resultant energy loss dE/dx (almost equal to) 0.5 GeV/fm. From the recent PHENIX data of high p{sub T} pi0 spectra in central Au+Au collisions at (square root)s=130 GeV, one extracts an energy loss for a 10 GeV parton that is equivalent to dE/dx=7.3 GeV/fm in a static medium with the same gluon density as in the initial stage of the collision at tau0=0.2 fm/c. Constraints on jet quenching by the central rapidity density of charged hadrons is also discussed.


W and Z Boson Production with Jets and Inclusive Jet Production in P Pbar Collisions at Square Root S

W and Z Boson Production with Jets and Inclusive Jet Production in P Pbar Collisions at Square Root S

Author:

Publisher:

Published: 1996

Total Pages: 9

ISBN-13:

DOWNLOAD EBOOK

The production properties of jets produced in p{ovr p} collisions at (square root)s = 1.8 TeV have been measured using the CDF detector. The data are compared to predictions of leading order and next to leading order QCD predictions. Both inclusive jets and those produced in association with W and Z bosons are used for this analysis. In general, good agreement with QCD predictions is found except for very high E{sub t} inclusive jets. 10 refs., 7 figs., 2 tabs.


Jet Fragmentation at the LHC

Jet Fragmentation at the LHC

Author: Benjamin Tyler Elder

Publisher:

Published: 2018

Total Pages: 245

ISBN-13:

DOWNLOAD EBOOK

Run II at the LHC is pushing the energy and luminosity frontiers, and challenging the theory community to develop new tools both to increase the precision of our predictions and to expand their scope to match measurements of a more diverse set of observables. In this work, we describe the use of a new class of non-perturbative functions called Generalized Fragmentation Functions (GFFs) as a step towards these goals. This theoretical framework enables the calculation of a broad set of semi-inclusive jet observables. We explore known observables whose distributions can now be calculated using GFFs, and construct a new class of non-associative "fractal observables" which can be described with GFFs. As an important application, we calculate the spectrum of track-assisted mass, which can be measured experimentally with much better angular resolution than ordinary jet mass, including the effect of Soft-Drop grooming. In order to make connections to frameworks for describing Quantum Chromodynamics, we discuss the relationship between GFFs and the Generating Functional Approach (GFA).


Introduction to Soft-Collinear Effective Theory

Introduction to Soft-Collinear Effective Theory

Author: Thomas Becher

Publisher: Springer

Published: 2015-03-04

Total Pages: 214

ISBN-13: 3319148486

DOWNLOAD EBOOK

Among resummation techniques for perturbative QCD in the context of collider and flavor physics, soft-collinear effective theory (SCET) has emerged as both a powerful and versatile tool, having been applied to a large variety of processes, from B-meson decays to jet production at the LHC. This book provides a concise, pedagogical introduction to this technique. It discusses the expansion of Feynman diagrams around the high-energy limit, followed by the explicit construction of the effective Lagrangian - first for a scalar theory, then for QCD. The underlying concepts are illustrated with the quark vector form factor at large momentum transfer, and the formalism is applied to compute soft-gluon resummation and to perform transverse-momentum resummation for the Drell-Yan process utilizing renormalization group evolution in SCET. Finally, the infrared structure of n-point gauge-theory amplitudes is analyzed by relating them to effective-theory operators. This text is suitable for graduate students and non-specialist researchers alike as it requires only basic knowledge of perturbative QCD.


Open Quantum Systems Far from Equilibrium

Open Quantum Systems Far from Equilibrium

Author: Gernot Schaller

Publisher: Springer

Published: 2014-01-07

Total Pages: 215

ISBN-13: 331903877X

DOWNLOAD EBOOK

This monograph provides graduate students and also professional researchers aiming to understand the dynamics of open quantum systems with a valuable and self-contained toolbox. Special focus is laid on the link between microscopic models and the resulting open-system dynamics. This includes how to derive the celebrated Lindblad master equation without applying the rotating wave approximation. As typical representatives for non-equilibrium configurations it treats systems coupled to multiple reservoirs (including the description of quantum transport), driven systems and feedback-controlled quantum systems. Each method is illustrated with easy-to-follow examples from recent research. Exercises and short summaries at the end of every chapter enable the reader to approach the frontiers of current research quickly and make the book useful for quick reference.