scholarly journals Momentum fractions carried by quarks and gluons in models of proton structure functions at small x

2017 ◽  
Vol 32 (18) ◽  
pp. 1750107 ◽  
Author(s):  
D. K. Choudhury ◽  
Baishali Saikia ◽  
K. Kalita
Keyword(s):  
Phenomenological Models ◽  
The Self ◽  
Proton Structure Function ◽  
Self Similarity ◽  
Proton Structure ◽  
Second Moments ◽  
Linear Rise ◽  
Small X ◽  
Comprehensive Comparison

In this paper, we report an analysis of partial momentum fractions carried by quarks and gluons in six alternative phenomenological models of proton structure function valid in limited small [Formula: see text] regions: [Formula: see text], [Formula: see text] to 6; the limits being determined by phenomenological range of validity in each model. Since the physics of small [Formula: see text] is not completely understood at this point, we have considered both self-similarity-based as well as QCD-based models. The procedure by which one can determine the applicability ranges in [Formula: see text] and [Formula: see text] of the models is presented. We find that while the self-similarity-based models with linear rise in [Formula: see text] has limited phenomenological ranges of validity, an improved version with linear rise in [Formula: see text] has a wider phenomenological range. We then compare the partial momentum fractions in all the small [Formula: see text] models. Our analysis implies that the role of small [Formula: see text] sea quarks in calculating the second moments of parton distribution is minor one. We have also made a comprehensive comparison of all the phenomenological models considered to the available perturbative QCD, lattice QCD as well as Ads/QCD results.

Q2 dependence of the fractional momenta carried by small x quarks and gluons in models of proton structure function

2019 ◽  
Vol 34 (33) ◽  
pp. 1950273
Author(s):  
Luxmi Machahari ◽  
D. K. Choudhury
Keyword(s):  
Structure Function ◽  
Gluon Distribution ◽  
Taylor Expansion ◽  
Total Momentum ◽  
Analytical Models ◽  
Proton Structure Function ◽  
Self Similarity ◽  
Theor Phys ◽  
Proton Structure ◽  
Small X

Recently, we suggested two alternative analytical models of proton structure function [Formula: see text] and gluon distribution [Formula: see text] at small [Formula: see text] [L. Machahari and D. K. Choudhury, Eur. Phys. J. A 54, 69 (2018); Commun. Theor. Phys. 71, 56 (2019)] derived from the coupled DGLAP equations for quarks and gluons approximated by Taylor expansion. In this work, we compute the partial momentum fractions carried by quarks and gluons in limited small [Formula: see text] range: [Formula: see text] and compare them with few other models available in the current literature. The analysis leads to understand qualitatively the effects of notions like Froissart saturation and self-similarity in the proton at small [Formula: see text]. We also study if our results conform to the total momentum fractions as predicted in perturbative and lattice QCD.

scholarly journals Froissart bound and self-similarity based models of proton structure functions

2018 ◽  
Vol 33 (08) ◽  
pp. 1850046 ◽  
Author(s):  
D. K. Choudhury ◽  
Baishali Saikia
Keyword(s):  
Structure Function ◽  
Cross Section ◽  
Structure Functions ◽  
Proton Structure Function ◽  
Self Similarity ◽  
Proton Proton ◽  
Proton Structure

Froissart bound implies that the total proton–proton cross-section (or equivalently proton structure function) cannot rise faster than [Formula: see text]. Compatibility of such behavior with the notion of self-similarity in proton structure function was suggested by us sometime back. In the present work, we generalize and improve it further by considering more recent self-similarity based models of proton structure functions and compare with recent data as well as with the model of Block, Durand, Ha and McKay.

scholarly journals AN ANALYSIS OF MOMENTUM FRACTIONS OF QUARKS AND GLUONS IN A MODEL OF PROTON

2013 ◽  
Vol 28 (19) ◽  
pp. 1350086 ◽  
Author(s):  
AKBARI JAHAN ◽  
D. K. CHOUDHURY
Keyword(s):  
Structure Function ◽  
Upper Bounds ◽  
Proton Structure Function ◽  
Lower And Upper Bounds ◽  
Self Similarity ◽  
Sum Rule ◽  
Proton Structure

Momentum sum rule can be used as an inequality to estimate the lower and upper bounds of the momentum fractions of quarks and gluons in a model of proton valid in a limited x range. We compute such bounds in a self-similarity based model of proton structure function valid in the range 6.2 × 10-7 ≤ x ≤ 10-2. The results conform to the asymptotic QCD expectations.

scholarly journals A phenomenological solution small x to the longitudinal structure function dynamical behavior

2014 ◽  
Vol 29 (32) ◽  
pp. 1450189 ◽  
Author(s):  
G. R. Boroun ◽  
B. Rezaei ◽  
J. K. Sarma
Keyword(s):  
Structure Function ◽  
Dynamical Behavior ◽  
Structure Functions ◽  
Proton Structure Function ◽  
Leading Order ◽  
Longitudinal Structure ◽  
Proton Structure ◽  
Longitudinal Structure Function ◽  
Color Dipole ◽  
Small X

In this paper, the evolutions of longitudinal proton structure function have been obtained at small x up to next-to-next-to-leading order using a hard Pomeron behavior. In our paper, evolutions of gluonic as well as heavy longitudinal structure functions have been obtained separately and the total contributions have been calculated. The total longitudinal structure functions have been compared with results of Donnachie–Landshoff (DL) model, Color Dipole (CD) model, kT factorization and H1 data.

Scaling violations of the proton structure function F2 at small x

1994 ◽  
Vol 321 (1-2) ◽  
pp. 161-167 ◽  
Author(s):  
I. Abt ◽  
T. Ahmed ◽  
V. Andreev ◽  
B. Andrieu ◽  
R.-D. Appuhn ◽  
...  
Keyword(s):  
Structure Function ◽  
Proton Structure Function ◽  
Proton Structure ◽  
Small X ◽  
Scaling Violations

Parton Distribution Functions and models of proton structure functions with self-similarity

2016 ◽  
Vol 31 (34) ◽  
pp. 1650176 ◽  
Author(s):  
D. K. Choudhury ◽  
Baishali Saikia
Keyword(s):  
Structure Function ◽  
Initial Conditions ◽  
Parton Density ◽  
Distribution Functions ◽  
Proton Structure Function ◽  
Model Parameters ◽  
Self Similarity ◽  
Parton Density Function ◽  
Transverse Momentum Dependent ◽  
Proton Structure

Sometime back, a self-similarity based model of the proton structure function at small [Formula: see text] was proposed by Lastovicka. We make reanalysis of this model with most recent HERA data. No significance difference with the earlier analysis is found. Both the analyses have singularity within the kinematical range of [Formula: see text]: [Formula: see text]. We therefore study the model with the additional assumption that it should be singularity free, imposing positivity conditions on the model parameters. This results in a new model which is, however, phenomenologically valid only in a limited low [Formula: see text] range. We therefore make further generalization of the defining self-similar unintegrated Parton Density Function (uPDF) and show that the with proper generalizations and initial conditions on them not only remove the undesired singularity but also results in a structure function with logarithmic growth in [Formula: see text] closer to QCD. The phenomenological range of validity is then found to be much larger than the earlier versions. We also extrapolate the models to large [Formula: see text] in a parameter-free way. The possibility of incorporation of Transverse Momentum Dependent (TMD) PDF in this approach is explored as well.

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