Nucleon’s energy–momentum tensor form factors in light-cone QCD

Abstract

We use the energy-momentum tensor (EMT) current to compute the EMT form factors of the nucleon in the framework of the light cone QCD sum rule formalism. In the calculations, we employ the most general form of the nucleon's interpolating field and use the distribution amplitudes (DAs) of the nucleon with two sets of the numerical values of the main input parameters entering the expressions of the DAs. The directly obtained results from the sum rules for the form factors are reliable at Q 2 ≥ 1 GeV 2 : To extrapolate the results to include the zero momentum transfer squared with the aim of estimation of the related static physical quantities, we use some fit functions for the form factors. The numerical computations show that the energy-momentum tensor form factors of the nucleon can be well fitted to the multipole fit form. We compare the results obtained for the form factors at Q 2 = 0 with the existing theoretical predictions as well as experimental data on the gravitational form factor d q 1 (0). For the form factors M q 2 (0) and J q (0) a consistency among the theoretical predictions is seen within the errors: Our results are nicely consistent with the Lattice QCD and chiral perturbation theory predictions. However, there are large discrepancies among the theoretical predictions on d q 1 (0). Nevertheless, our prediction is in accord with the JLab data as well as with the results of the Lattice QCD, chiral perturbation theory and KM15-fit. Our fit functions well define most of the JLab data in the interval Q 2 ∈ [0, 0.4] GeV 2 , while the Lattice results suffer from large uncertainties in this region. As a by-product, some mechanical properties of the nucleon like the pressure and energy density at the center of nucleon as well as its mechanical radius are also calculated and their results are compared with other existing theoretical predictions.

Gravitational form factors of a baryon with spin-3/2

“…The GFFs of the spin-0 hadrons are investigated in the chiral quark model [23,24], lattice QCD [25], the parameter fitting from experimental data [26], and the Nambu-Jona-Lasinio (NJL) model [27]. For the spin-1/2 hadrons, there are results from the effective chiral theory [28], the chiral quarksoliton model [29,30], the SU(2) Skyrme model [31,32], the π −ρ−ω model [33,34], the bag model [35], the QCD sum rule [36,37] and the lattice QCD [38,39]. The renormalization group properties of the nucleon's twist-four GFF c q,g (t) 1 , which plays a role in the nucleon's transverse spin sum rule, are studied in Ref.…”

Determination of the generalized parton distributions through the analysis of the world electron scattering data considering two-photon exchange corrections

“…Note that if both t and ξ are set to zero, the M 2 will be a simple sum of the momentum fractions carried by quarks, since GPDs H q (x) turn into the ordinary PDFs q(x). Although there are no experimental measurements of M 2 (t) unlike the D-term d 1 (t), it is interesting to compare our results with the corresponding ones obtained from the light-cone QCD sum rules (LCSR) [38]. Such a comparison has been shown in Fig.…”

“…9. A comparison between our results obtained for M2(t) using Set 4 and Set 5 of GPDs and the corresponding one calculated using LCSR [38].…”

“…9 is the averaged results of LCSR presented in Ref. [38] that has been evolved to µ = 2 GeV using the the renormalisation group equations extended to include mass renormalisation (the original results are belonging to µ = 1 GeV).…”

Gravitational transition form factors of N(1535)→N

“…Hence, the investigation of these FFs receives significant interest for comprehension of the internal structure of the nucleon. The GFFs of the nucleon have been examined within different theoretical models such as, chiral quark soliton model (χQSM) [1][2][3][4][5][6][7][8][9][10][11], lattice QCD [12][13][14][15][16][17][18][19], light-cone QCD sum rules (LCSR) [20,21], Skyrme model [22,23], chiral perturbation theory (χPT) [24][25][26][27][28][29], Bag model [30], and, instant and front form (IFF) [31]. Interested readers can find more details about these studies in a recent review [32].…”