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Register a new userHadronic sizes and observables in high-energy scattering
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The functional dependence of the high-energy observables of total cross section and slope parameter on the sizes of the colliding hadrons predicted by the model of the stochastic vacuum and the corresponding relations used in the geometric model of Povh and Hufner are confronted with the experimental data. The existence of a universal term in the expression for the slope, due purely to vacuum effects, independent of the energy and of the particular hadronic system, is investigated. Accounting for the two independent correlation functions of the QCD vacuum, we improve the simple and consistent description given by the model of the stochastic vacuum to the high-energy pp and pbar-p data, with a new determination of parameters of non-perturbative QCD. The increase of the hadronic radii with the energy accounts for the energy dependence of the observables.
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The commonly used West and Yennie model approach to the description of the interference between Coulomb and hadronic scattering of nucleons is critically examined and its deficiencies are clarified. The preference of the more general eikonal model approach is summarized.
Using a unified analytic representation for the elastic scattering amplitudes of pp scattering valid for all high energy region, the behavior of observables in the LHC collisions in the range $sqrt{s}$ = 2.76 - 14 TeV is discussed. Similarly to the case of 7 TeV data, the proposed amplitudes give excellent description of the preliminary 8 TeV data. We discuss the expected energy dependence of the observable quantities, and present predictions for the experiments at 2.76, 13 and 14 TeV.
The strange-anticharmed Pentaquark is a $uudbar{c}s$ or $uddbar{c}s$ five-quark baryon that is expected to be either a narrow resonance, or possibly even stable against strong and electromagnetic decay. We describe this hyperon here, its structure, binding energy and lifetime, resonance width, production mechanisms, production cross sections, and decay modes. We describe techniques to reduce backgrounds in search experiments and to optimize the conditions for Pentaquark observation. Possibilities for enhancing the signal over background in Pentaquark searches are investigated by examining predictions for detailed momentum and angular distributions in multiparticle final states. General model-independent predictions are presented as well as those from two models: a loosely bound $D_{s}^-N$ molecule and a strongly-bound five-quark system. Fermilab E791 data, currently being analyzed, may have marginal statistics for showing definitive signals. Future experiments in the spirit of the recent CHARM2000 workshop, such as FNAL E781 and CERN CHEOPS with $10^6-10^7$ reconstructed charmed baryon events, should have sensitivity to determine whether or not the Pentaquark exists.
This paper presents a qualitative explanation for the hollowness effect based on the inelastic overlap function, claiming this result is a consequence of fundamental thermodynamic processes. Using the Tsallis entropy, one identifies the entropic index $w$ with the ratio of the collision energy to critical one in the total cross-section. The integrated probability density function is replaced by the inelastic overlap function, which represents the probability of occurrence of an inelastic event depending on both the collision energy and impact parameter. The Coulomb potential, as well as the confinement potential, are used as naive approaches to describe the (internal) energy of the colliding hadrons. The Coulomb potential in the impact parameter picture is not able to furnish any reliable physical result near the forward direction. However, the confinement potential in the impact parameter space results in the hollowness effect shown by the inelastic overlap function near the forward direction.
We calculate the amplitude of the rare flavour-changing neutral-current decay $Bto piell^+ell^-$ at large recoil of the pion. The nonlocal contributions in which the weak effective operators are combined with the electromagnetic lepton-pair emission are systematically taken into account. These amplitudes are calculated at off-shell values of the lepton-pair mass squared, $q^2<0$, employing the operator-product expansion, QCD factorization and light-cone sum rules. The results are fitted to hadronic dispersion relations in $q^2$, including the intermediate vector meson contributions. The dispersion relations are then used in the physical region $q^2>0$. Our main result is the process-dependent addition $Delta C^{(Bpi)}_9(q^2)$ to the Wilson coefficient $C_9$ obtained at $4m_ell^2<q^2lesssim m_{J/psi}^2$. Together with the $Bto pi$ form factors from light-cone sum rules, this quantity is used to predict the differential rate, direct CP-asymmetry and isospin asymmetry in $Bto piell^+ell^-$. We also estimate the total rate of the rare decay $Bto pi ubar{ u}$.
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