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Register a new userThe explicit procedures for reconstruction of full set of helicity amplitudes in elastic proton-proton and proton-antiproton collisions
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The explicit procedures are described for reconstruction of the full set of helicity amplitudes in proton-proton and proton-antiproton elastic scattering. The procedures are based on the derivative relations for the helicity amplitudes in s-channel, on the explicit parametrization of the leading spin non flip amplitudes and crossing - symmetry relations. Asymptotic theorems are used for definition of free parameters in derivative relations. We also study the Odderon influence on the helicity amplitude reconstruction. Reconstruction procedures are valid at extremely wide energy domain and broad range of momentum transfer. These procedures might be useful in studying the spin phenomena in proton-proton and proton-antiproton elastic scattering.
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Motivated by the present extensive RHIC (BNL) spin program and further PAX project at FAIR, we study the possibility of explicit reconstruction of full set of helicity amplitudes by joint consideration of elastic proton-proton and proton-antiproton scattering. Procedure is based on the derivative relations for the helicity amplitudes, explicit parametrization of the leading spin non-flip amplitudes and crossing - symmetry relations. Some preliminary results are presented for the PAX energies to show the expected magnitudes of the spin dependent observables as a functions of invariant Mandelstams variables $s$ and $t$.
The analysis of data on hyperon transverse momentum distributions, dN/dPt, that were gathered from various experiments (ISR, STAR, UA1, UA5 and CDF) reveals an important difference in the dynamics of multiparticle production in proton-proton vs. antiproton-proton collisions in the region of transverse momenta 0.3 GeV/c < Pt < 3 GeV/c. Hyperons produced with proton beams display the sharp exponential slope at low Pt, while spectra prodused with antiproton beam dont. Since LHC experiments have proton projectiles, the spectra of baryon production should seem softer in comparison to expectations, because the Monte Carlo simulations were based on the Tevatron antiproton-proton data. From the point of view of Quark-Gluon String Model, the most important contribution into the particle production spectra goes from antidiquark-diquark string fragmentation that exists only in the topological diagram for antiproton-proton collisions and is a very interesting object for investigation even at lower energies. This study may have an impact not only on interpretation of LHC results, but also on the cosmic ray physics and astrophysics, where the baryon contribution into matter-antimatter asymmetry is being studied.
We consider the azimuthal correlations of charged hadron pairs with large total transverse momentum and small relative momentum, produced in proton-proton collisions with one transversely polarized proton. One of these correlations directly probes the chiral-odd transversity parton distribution in connection with a chiral-odd interference fragmentation function. We present predictions for this observable based on previous extractions of transversity (from charged pion pair production in semi-inclusive deep-inelastic scattering) and of the interference fragmentation function (from the production of back-to-back charged pion pairs in electron-positron annihilations). All analyses are performed in the framework of collinear factorization. We compare our predictions to the recent data on proton-proton collisions released by the STAR collaboration at RHIC, and we find them reasonably compatible. This comparison confirms for the first time the predicted role of transversity in proton-proton collisions and it allows to test its universality.
We present an overview of the measurements of the like-sign dimuon charge asymmetry by the DO Collaboration at the Fermilab Tevatron proton-antiproton Collider. The results differ from the Standard Model prediction of CP violation in mixing and interference of B^0 and B^0_s by 3.6 standard deviations.
We establish some signatures of the extra bilepton boson ${X^0}$ predicted in the ${SU (3)_C times SU (3)_L times U (1)_X}$ model with right-handed neutrinos. We analyze the process $p + p longrightarrow X^0 +X^{0*} + {hbox {anything}}$, for center of mass energy regime of the Large Hadron Collider. The main contributions for the neutral bilepton production in $q bar q$ process come from the $s-$channel ($Z$ and $Z^prime$ exchanges), when the initial quarks have charge 2/3, and from an additional $t-$channel (heavy quark exchange) when they have -1/3 of the positron electric charge. We calculate some distributions of the final bileptons and from these results we conclude that LHC can show a clear signature for the existence of the $X^0$ predicted in the 3-3-1 model.
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