118555510
SEMILEPTONIC DECAY OF Bc MESON INTO $c\bar c$ STATES IN A QCD POTENTIAL MODEL
The slope and curvature of Isgur–Wise function for Bc meson is computed in a QCD potential model in two different approaches of choosing the perturbative term of the Cornell potential. Based on heavy quark effective theory the exclusive semileptonic decay rates of Bc meson into the states are exploited. Spin symmetry breaking effects are ignored up to a particular point and the form factors are connected with Isgur–Wise function for other kinematic point since the recoil momentum of from Bc is small due to its heavy mass.
123165880
A solution of the DGLAP equation for gluon at low x
We obtain a solution of the DGLAP equation for the gluon at low x first by expanding the gluon in a Taylor series and then using the method of characteristics. We test its validity by comparing it with that of Glück, Reya and Vogt. The convergence criteria of the approximation used are also discussed. We also calculate εF2(x,Q)2/ε In Q2 using its approximate relations with the gluon distribution at low x. The predictions are then compared with the HERA data.
119568734
Masses in structure functions
We derive an approximate formula for the quark mass in ξ-formalism. Using the QCD-based form of structure function, we analyse the SLAC-MIT data to estimate the experimentally allowed ranges of quark mass. The possible variation of our results with QCD cut-off parameter, gluon distribution, hard intrinsic charm component of the proton wavefunction and the higher twist effects are also discussed.
119205638
A lower bound on the Longitudinal Structure Function at small x from a self-similarity based model of Proton
Self-similarity based model of proton structure function at small \textit{x} was reported in the literature sometime back. The phenomenological validity of the model is in the kinematical region $ 6.2\, \times \, 10^{-7} \leq x \leq 10^{-2}$ and $ 0.045 \leq Q^{2} \leq 120 \, \mathrm{GeV^{2}} $. We use momentum sum rule to pin down the corresponding self-similarity based gluon distribution function valid in the same kinematical region. The model is then used to compute bound on the longitudinal structure function $F_{L}\left(x,Q^{2} \right)$ for Altarelli-Martinelli equation in QCD and is compared with the recent HERA data.
123500672
Phenomenological structure functions and Gribov-Lipatov relation
We make an analysis of the Gribov-Lipatov relation using the phenomenological forms of the structure functionF2ep. Our analysis indicate breakdown of the relation at PETRA energies. Plausible reasons of the breakdown of Gribov-Lipatov relation are discussed together with its phenomenological form.
120396984
Free-field theory, fixed-point theory, and electron-positron annihilation into hadrons
The R problem of electron-positron physics is analyzed within the frameworks of a free-field theory (parton models) and a field theory with an infrared-stable fixed point. Present data do not rule out either of these models and hence they both can survive as alternatives to standard QCD in the R problem.
119329980
Compton Scattering on He-3
We present first calculations for Compton scattering on $^3$He. The objective of the calculation is an extraction of the neutron polarizabilities.
119348603
Predictions for polarized-beam and/or vector-polarized-target observables in elastic Compton scattering on the deuteron
Motivated by ongoing developments at High-Intensity Gamma Source (HI\ensuremath{\gamma}S) at Triangle Universities Nuclear Laboratory (TUNL) that include increased photon flux and the ability to circularly polarize photons, we calculate several beam-polarization and/or target-spin-dependent observables for elastic Compton scattering on the deuteron. This is done at energies of the order of the pion mass within the framework of heavy-baryon chiral perturbation theory. Our calculation is complete to $\mathcal{O}({Q}^{3})$ and at this order there are no free parameters. Consequently, the results reported here are predictions of the theory. We discuss paths that may lead to the extraction of neutron polarizabilities. We find that the photon/beam polarization asymmetry is not a good observable for the purpose of extracting ${\ensuremath{\alpha}}_{n}$ and ${\ensuremath{\beta}}_{n}$. However, one of the double polarization asymmetries, ${\ensuremath{\Sigma}}_{x}$, shows appreciable sensitivity to ${\ensuremath{\gamma}}_{1n}$ and could be instrumental in pinning down the neutron spin polarizabilities.