scholarly journals PROTON STRUCTURE FUNCTIONS FROM CHIRAL DYNAMICS AND QCD CONSTRAINTS

1999 ◽  
Vol 14 (19) ◽  
pp. 3005-3027 ◽  
Author(s):  
H. J. WEBER
Keyword(s):  
Field Theory ◽  
Goldstone Boson ◽  
Detailed Comparison ◽  
Structure Functions ◽  
Proton Spin ◽  
Chiral Field ◽  
Pure Spin ◽  
Regge Behavior ◽  
Order Of Magnitude ◽  
Bjorken X

The spin fractions and deep inelastic lepton structure functions of the proton are analyzed using chiral field theory involving Goldstone bosons. A detailed comparison with recent chiral models sheds light on their successful description of the spin fractions of the proton as being due to neglecting helicity nonflip chiral transitions. This approximation is valid for zero mass but not for constituent quarks. Since the chiral spin fraction models with the pure spin-flip approximation reproduce the measured spin fractions of the proton, axialvector constituent-quark-Goldstone boson couplings are found to be inconsistent with the proton spin data. Initial quark valence distributions are then constructed using quark counting constraints at Bjorken x→1 and Regge behavior at x→0. Sea quark distributions predicted by chiral field theory on this basis have the correct order of magnitude and shape. The spin fractions also agree with the data.

scholarly journals PROTON STRUCTURE FUNCTIONS FROM CHIRAL DYNAMICS AND QCD CONSTRAINTS

1998 ◽  
Vol 13 (01) ◽  
pp. 71-82 ◽  
Author(s):  
H. J. WEBER
Keyword(s):  
Field Theory ◽  
Detailed Comparison ◽  
Structure Functions ◽  
Chiral Field ◽  
Quark Masses ◽  
Goldstone Bosons ◽  
Proton Structure ◽  
Regge Behavior ◽  
Small X ◽  
Bjorken X

The spin fractions and deep inelastic lepton structure functions of the proton are analyzed based on chiral field theory invloving Goldstone bosons. A detailed comparison with several recent chiral models sheds light on their successful description of the spin fractions of the proton as being due to neglecting quark masses. Initial quark valence distributions at a higher scale than Λ QCD are constructed using quark counting constraints at large Bjorken x→1 and Regge behavior at small x. Reasonable strange quark distributions are then predicted by chiral field theory. The spin fractions also agree with the data.

scholarly journals EVOLUTION OF STRUCTURE FUNCTIONS AND THEIR MOMENTS IN CHIRAL FIELD THEORY

2003 ◽  
Vol 18 (04) ◽  
pp. 593-606
Author(s):  
KAKALI RAY-MAITY ◽  
PADMANABHA DASGUPTA
Keyword(s):  
Field Theory ◽  
Evolution Equations ◽  
Probabilistic Approach ◽  
Perturbation Expansion ◽  
Structure Functions ◽  
Evolution Process ◽  
Effective Theory ◽  
Chiral Field ◽  
Coupling Constant ◽  
Evolution Of Structure

Evolution of structure functions and their moments at low and moderate Q2 is studied in the chiral field theory. Evolution equations based on perturbation expansion in the coupling constant of the effective theory are derived and solved for the moments. The kernels of evolution arising from different processes have been calculated with contributions from direct and cross channels, the interference terms being non-negligible in the kinematic regions under consideration. This is shown to lead to flavor-dependence of the kernels which manifests in observable effects. The invalidity of the probabilistic approach to the evolution process is also pointed out.

Light front field theory: An advanced Primer

2007 ◽  
Vol 57 (3) ◽  
Author(s):  
L'ubomír Martinovič
Keyword(s):  
Field Theory ◽  
Detailed Comparison ◽  
Light Front ◽  
Two Dimensional ◽  
Schwinger Model ◽  
Initial Space ◽  
Model Hamiltonian ◽  
Spatial Volume ◽  
Hamiltonian Perturbation Theory ◽  
Light Front Quantization

Light front field theory: An advanced PrimerWe present an elementary introduction to quantum field theory formulated in terms of Dirac's light front variables. In addition to general principles and methods, a few more specific topics and approaches based on the author's work will be discussed. Most of the discussion deals with massive two-dimensional models formulated in a finite spatial volume starting with a detailed comparison between quantization of massive free fields in the usual field theory and the light front (LF) quantization. We discuss basic properties such as relativistic invariance and causality. After the LF treatment of the soluble Federbush model, a LF approach to spontaneous symmetry breaking is explained and a simple gauge theory - the massive Schwinger model in various gauges is studied. A LF version of bosonization and the massive Thirring model are also discussed. A special chapter is devoted to the method of discretized light cone quantization and its application to calculations of the properties of quantum solitons. The problem of LF zero modes is illustrated with the example of the two-dimensional Yukawa model. Hamiltonian perturbation theory in the LF formulation is derived and applied to a few simple processes to demonstrate its advantages. As a byproduct, it is shown that the LF theory cannot be obtained as a "light-like" limit of the usual field theory quantized on an initial space-like surface. A simple LF formulation of the Higgs mechanism is then given. Since our intention was to provide a treatment of the light front quantization accessible to postgradual students, an effort was made to discuss most of the topics pedagogically and a number of technical details and derivations are contained in the appendices.

scholarly journals Precision Higgs couplings in neutral naturalness models: an effective field theory approach

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Lucien Heurtier ◽  
Hao-Lin Li ◽  
Huayang Song ◽  
Shufang Su ◽  
Wei Su ◽  
...  
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Goldstone Boson ◽  
Higgs Sector ◽  
New Physics ◽  
Effective Field ◽  
Precision Measurements ◽  
Global Symmetry ◽  
Theory Approach ◽  
Decay Channels

AbstractThe Higgs sector in neutral naturalness models provides a portal to the hidden sectors, and thus measurements of Higgs couplings at current and future colliders play a central role in constraining the parameter space of the model. We investigate a class of neutral naturalness models, in which the Higgs boson is a pseudo-Goldstone boson from the universal SO(N)/SO(N −1) coset structure. Integrating out the radial mode from the spontaneous global symmetry breaking, we obtain various dimension-six operators in the Standard Model effective field theory, and calculate the low energy Higgs effective potential with radiative corrections included. We perform aχ2fit to the Higgs coupling precision measurements at current and future colliders and show that the new physics scale could be explored up to 2.3 (2.4) TeV without (with) the Higgs invisible decay channels at future Higgs factories. The limits are comparable to the indirect constraints obtained via electroweak precision measurements.

Finite nuclei in a pure fermionic chiral field theory

1987 ◽  
Vol 194 (3) ◽  
pp. 331-333 ◽  
Author(s):  
Volker Koch ◽  
Bernard Blättel ◽  
Ulrich Mosel
Keyword(s):  
Field Theory ◽  
Chiral Field ◽  
Finite Nuclei

scholarly journals Convective differential rotation in stars and planets – I. Theory

2020 ◽  
Vol 498 (3) ◽  
pp. 3758-3781 ◽  
Author(s):  
Adam S Jermyn ◽  
Shashikumar M Chitre ◽  
Pierre Lesaffre ◽  
Christopher A Tout
Keyword(s):  
Differential Rotation ◽  
Detailed Comparison ◽  
Companion Paper ◽  
Angular Frequency ◽  
Circulation Rate ◽  
Rotation Rates ◽  
Rotating Systems ◽  
Order Of Magnitude ◽  
The Magnetic Field ◽  
Hydrodynamic Systems

ABSTRACT We derive the scaling of differential rotation in both slowly and rapidly rotating convection zones using order of magnitude methods. Our calculations apply across stars and fluid planets and all rotation rates, as well as to both magnetized and purely hydrodynamic systems. We find shear |R∇Ω| of order the angular frequency Ω for slowly rotating systems with Ω ≪ |N|, where N is the Brünt–Väisälä frequency, and find that it declines as a power law in Ω for rapidly rotating systems with Ω ≫ |N|. We further calculate the meridional circulation rate and baroclinicity and examine the magnetic field strength in the rapidly rotating limit. Our results are in general agreement with simulations and observations and we perform a detailed comparison with those in a companion paper.

scholarly journals STRUCTURE FUNCTIONS

2009 ◽  
Vol 24 (06) ◽  
pp. 1069-1086 ◽  
Author(s):  
CRISTINEL DIACONU
Keyword(s):  
Cross Sections ◽  
Structure Functions ◽  
Distribution Functions ◽  
Final States ◽  
Parton Distribution Functions ◽  
Proton Antiproton ◽  
Proton Proton ◽  
Proton Collisions ◽  
Bjorken X ◽  
Proton Proton Collisions

Recent progress in the understanding of the nucleon is presented. The unpolarized structure functions are obtained with unprecedented precision from the combined H1 and ZEUS data and are used to extract proton parton distribution functions via NLO QCD fits. The obtained parametrization displays an improved precision, in particular at low Bjorken x, and leads to precise predictions of cross-sections for LHC phenomena. Recent data from proton–antiproton collisions at Tevatron indicate further precise constraints at large Bjorken x. The flavor content of the proton is further studied using final states with charm and beauty in DIS ep and [Formula: see text] collisions. Data from polarized DIS or proton–proton collisions are used to test the spin structure of the proton and to constrain the polarized parton distributions.

Experimental and Numerical Characterization of the Flow Around the Keel of a Yacht

2008 ◽  
Author(s):  
Renata M. B. Chaves ◽  
Atila P. S. Freire ◽  
Alexandre T. P. Alho
Keyword(s):  
Laboratory Data ◽  
Turbulence Models ◽  
Detailed Comparison ◽  
Mean Velocity ◽  
Flow Parameters ◽  
Numerical Characterization ◽  
Sst Model ◽  
Order Of Magnitude ◽  
Measured Flow ◽  
Turbulence Data

The present work carries out a detailed comparison between numerical computations for the flow around the keel and the bulb of a sailboat and some newly obtained laboratory data. Two typical turbulence models are tested: the eddy-viscosity SST model and the second-moment model BSL-RSM-ω. Hot-wire anemometry (HWA) and particle image velocimetry (PIV) are used to characterize the flow around the keel and the bulb of a yacht. The experiments are conducted in a low speed wind tunnel. Measured flow parameters include the mean velocity profiles and second order moments. Both turbulence models are shown to perform well regarding mean velocity and global predictions. Turbulence data predictions, however, are shown to be erroneous by at least one order of magnitude.

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