scholarly journals Deep inelastic structure functions in light-front QCD: Radiative corrections

1999 ◽  
Vol 59 (9) ◽  
Author(s):  
A. Harindranath ◽  
Rajen Kundu ◽  
Wei-Min Zhang
Keyword(s):  
Structure Functions ◽  
Light Front ◽  
Radiative Corrections

Scaling for deuteron structure functions in a relativistic light-front model

1996 ◽  
Vol 53 (6) ◽  
pp. 3111-3130 ◽  
Author(s):  
W. N. Polyzou ◽  
W. Glöckle
Keyword(s):  
Structure Functions ◽  
Light Front ◽  
Front Model

scholarly journals Nonperturbative description of deep inelastic structure functions in light-front QCD

1999 ◽  
Vol 59 (9) ◽  
Author(s):  
A. Harindranath ◽  
Rajen Kundu ◽  
Wei-Min Zhang
Keyword(s):  
Structure Functions ◽  
Light Front

scholarly journals ONCE MORE ON THE RADIATIVE CORRECTIONS TO THE NUCLEON STRUCTURE FUNCTIONS IN QCD

1995 ◽  
Vol 10 (27) ◽  
pp. 2029-2039 ◽  
Author(s):  
D.B. STAMENOV
Keyword(s):  
Structure Functions ◽  
Nucleon Structure ◽  
Radiative Corrections ◽  
Parton Distributions ◽  
Logarithmic Approximation

A new representation of the next-to-leading QCD corrections to the nucleon structure functions is given in terms of parton distributions. All O(αs) corrections to the leading logarithmic approximation (LLA) are included. In contrast to the similar representations in the literature terms of order [Formula: see text] do not appear in our expressions for the nucleon structure functions taken in the next-to-leading logarithmic approximation. This result is generalized for any order in αs beyond the LLA. Terms of order [Formula: see text] which belong only to the approximation considered are present in such a representation for the structure functions.

scholarly journals Radiative corrections to the structure functions and sum rules in polarized dis

2000 ◽  
Vol 50 (S1) ◽  
pp. 159-164
Author(s):  
I. Akushevich ◽  
A. Ilyichev ◽  
N. Shumeiko
Keyword(s):  
Sum Rules ◽  
Structure Functions ◽  
Radiative Corrections

scholarly journals Meson/baryon/tetraquark supersymmetry from superconformal algebra and light-front holography

2016 ◽  
Vol 31 (19) ◽  
pp. 1630029 ◽  
Author(s):  
Stanley J. Brodsky ◽  
Guy F. de Téramond ◽  
Hans Günter Dosch ◽  
Cédric Lorcé
Keyword(s):  
Angular Momentum ◽  
Perturbative Qcd ◽  
Chiral Limit ◽  
Form Factors ◽  
Structure Functions ◽  
Mass Scale ◽  
Superconformal Algebra ◽  
Light Front ◽  
Spin Interaction ◽  
Excitation Spectra

Superconformal algebra leads to remarkable connections between the masses of mesons and baryons of the same parity — supersymmetric relations between the bosonic and fermionic bound states of QCD. Supercharges connect the mesonic eigenstates to their baryonic superpartners, where the mesons have internal angular momentum one unit higher than the baryons: [Formula: see text] The dynamics of the superpartner hadrons also match; for example, the power-law fall-off of the form factors are the same for the mesonic and baryonic superpartners, in agreement with twist counting rules. An effective supersymmetric light-front Hamiltonian for hadrons composed of light quarks can be constructed by embedding superconformal quantum mechanics into AdS space. This procedure also generates a spin–spin interaction between the hadronic constituents. A specific breaking of conformal symmetry inside the graded algebra determines a unique quark-confining light-front potential for light hadrons in agreement with the soft-wall AdS/QCD approach and light-front holography. Only one mass parameter [Formula: see text] appears; it sets the confinement mass scale, a universal value for the slope of all Regge trajectories, the nonzero mass of the proton and other hadrons in the chiral limit, as well as the length scale which underlies their structure. The mass for the pion eigenstate vanishes in the chiral limit. When one includes the constituent quark masses using the Feynman–Hellman theorem, the predictions are consistent with the empirical features of the light-quark hadronic spectra. Our analysis can be consistently applied to the excitation spectra of the [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] meson families as well as to the [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] baryons. We also predict the existence of tetraquarks which are degenerate in mass with baryons with the same angular momentum. The mass-squared of the light hadrons can be expressed in a universal and frame-independent decomposition of contributions from the constituent kinetic energy, the confinement potential, and spin–spin contributions. We also predict features of hadron dynamics, including hadronic light-front wave functions, distribution amplitudes, form factors, valence structure functions and vector meson electroproduction phenomenology. The mass scale [Formula: see text] can be connected to the parameter [Formula: see text] in the QCD running coupling by matching the nonperturbative dynamics, as described by the light-front holographic approach to the perturbative QCD regime. The result is an effective coupling defined at all momenta. The matching of the high and low momentum-transfer regimes determines a scale [Formula: see text] proportional to [Formula: see text] which sets the interface between perturbative and nonperturbative hadron dynamics. The use of [Formula: see text] to resolve the factorization scale uncertainty for structure functions and distribution amplitudes, in combination with the scheme-independent Principle of Maximal Conformality (PMC) procedure for setting renormalization scales, can greatly improve the precision of perturbative QCD predictions.

scholarly journals Color Confinement, Hadron Dynamics, and Hadron Spectroscopy from Light-Front Holography and Superconformal Algebra

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Stanley J. Brodsky
Keyword(s):  
Transverse Momentum ◽  
Structure Functions ◽  
Mass Scale ◽  
Superconformal Algebra ◽  
Light Front ◽  
Hamiltonian Equation ◽  
Hadron Spectroscopy ◽  
Fifth Dimension ◽  
Running Coupling ◽  
Momentum Distributions

The QCD light-front Hamiltonian equation HLFΨ=M2Ψ derived from quantization at fixed LF time τ=t  +  z/c provides a causal, frame-independent method for computing hadron spectroscopy as well as dynamical observables such as structure functions, transverse momentum distributions, and distribution amplitudes. The QCD Lagrangian with zero quark mass has no explicit mass scale. de Alfaro, Fubini, and Furlan (dAFF) have made an important observation that a mass scale can appear in the equations of motion without affecting the conformal invariance of the action if one adds a term to the Hamiltonian proportional to the dilatation operator or the special conformal operator. If one applies the dAFF procedure to the QCD light-front Hamiltonian, it leads to a color-confining potential κ4ζ2 for mesons, where ζ2 is the LF radial variable conjugate to the qq¯ invariant mass squared. The same result, including spin terms, is obtained using light-front holography, the duality between light-front dynamics and AdS5, if one modifies the AdS5 action by the dilaton eκ2z2 in the fifth dimension z. When one generalizes this procedure using superconformal algebra, the resulting light-front eigensolutions provide a unified Regge spectroscopy of meson, baryon, and tetraquarks, including remarkable supersymmetric relations between the masses of mesons and baryons and a universal Regge slope. The pion qq¯ eigenstate has zero mass at mq=0. The superconformal relations also can be extended to heavy-light quark mesons and baryons. This approach also leads to insights into the physics underlying hadronization at the amplitude level. I will also discuss the remarkable features of the Poincaré invariant, causal vacuum defined by light-front quantization and its impact on the interpretation of the cosmological constant. AdS/QCD also predicts the analytic form of the nonperturbative running coupling αs(Q2)∝e-Q2/4κ2. The mass scale κ underlying hadron masses can be connected to the parameter ΛMS¯ in the QCD running coupling by matching the nonperturbative dynamics to the perturbative QCD regime. The result is an effective coupling αs(Q2) defined at all momenta. One obtains empirically viable predictions for spacelike and timelike hadronic form factors, structure functions, distribution amplitudes, and transverse momentum distributions. Finally, I address the interesting question of whether the momentum sum rule is valid for nuclear structure functions.

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