SearcharxivSearch

arXiv subjects

M. Rosina

Publications and source records attributed to M. Rosina.

13 recordsLinked to original sources

Proton Spin in Deep Inelastic Scattering

So far the analyses of the polarized structure functions of the proton and neutron have been limited to the evaluation of their integrals and comparing them to the prediction of the static quark model of the nucleon. We extended our analysis to the x dependence of the polarized structure functions and observe: the measured structure function excellently agrees with the prediction of the static quark model for Bjorken $x>0.2$ and drops rapidly for $x<0.2$. It is suggested that for Bjorken $x>0.2$ electrons get scattered on the undamaged constituent quarks (alias valence quarks) denoted as quasi-elastic scattering on the constituent quarks and for $x<0.2$ the constituent quarks fragment. In the fragmentation strong interaction is involved which does not preserve the polarization.

hep-ph

The qq$\bar{\mathbf{q}}$ component in the constituent quark generates the pion cloud of the nucleon

The spin properties and the flavor asymmetric sea of the nucleon can be well explained by assuming that each constituent quark is surrounded with about 30% probability by a quark-antiquark pair coupled to the pion quantum numbers. We show that about one quarter of these quark-antiquark pairs show up as the pion in $\p\to\nπ^+$ and $\p\to\pπ^0$ fluctuation in agreement with the observed value in the ($\e+\p\to\e+$ forward neutron+X) experiment.

hep-ph

Proceedings to the 13th Workshop 'What Comes Beyond the Standard Models', Bled, July 12. - 22., 2010, Slovenia

1. Noncommutativity and Topology within Lattice Field Theories 2. The Construction of Quantum Field Operators 3. The Bargmann-Wigner Formalism for Spin 2 Fields 4. New Light on Dark Matter from the LHC 5. Extra Dimensional Metric Reversal Symmetry and its Prospect... 6. Masses and Mixing Matrices of Families within SU(3) Flavor Symmetry ... 7. Dark Atoms of the Universe: OHe Nuclear Physics, 8. Can the Matter-Antimatter Asymmetry be Easier to Understand Within the "Spin-charge-family-theory", .. 9. Mass Matrices of Twice Four Families of Quarks and Leptons, ...in the "Spin-charge-family-theory" 10. Bohmian Quantum Mechanics or What Comes Before the Standard Model 11. Backward Causation in Complex Action Model ... 12. Is the Prediction of the "Spin-charge-family-theory" in Disagreement with the XENON100..? 13. Masses and Mixing Matrices of Families of Quarks and Leptons Within the "Spin-charge-family-theory" 14. Can the Stable Fifth Family of the "Spin-charge-family-theory" ...Form the Fifth Antibaryon Clusters with Ordinary He Nucleus? 15. Puzzles of Dark Matter - More Light on Dark Atoms? 16. Families of Spinors in d = (1 + 5)...and Masslessness 17. Are Superheavy Quark Clusters Candidates for the Dark Matter? 18. Complex Action Functioning as Cutoff and De Broglie-Bohm Particle 19. Where does the Science Go? 20. VIA Presentation

hep-ph

The Tcc = DD* molecular state

We show that the molecule-like configuration of DD^* enables weak binding with two realistic potential models (Bhaduri and Grenoble AL1). Three-body forces may increase the binding and strengthen the cc diquark configuration. As a signature we propose the branching ratio between radiative and pionic decay.

hep-ph

Production and detection of doubly charmed tetraquarks

The feasibility of tetraquark detection is studied. For the cc\bar{u}\bar{d} tetraquark we show that in present (SELEX, Tevatron, RHIC) and future facilities (LHCb, ALICE) the production rate is promising and we propose some detectable decay channels.

hep-ph

The Production and Decay of Heavy Dimesons

We show that it is necessary to go beyond a single hadron (beyond the quark-antiquark or three-quark systems) in order to distinguish the colour structure of the effective quark-quark interaction and the relevance of 3-body forces. We critically discuss the proposed models which suggest the dimeson bb\bar{u}\bar{d} to be bound by ~ 100 MeV and the cc\bar{u}\bar{d} dimeson to be unbound. Only experiment can judge. We estimate the probability of producing bb-\bar{u}\bar{d} at LHC by double gluon-gluon fusion and search for a characteristic decay.

hep-ph

The Chances to Produce and Detect the b-b-ubar-dbar Tetraquark at LHC

In the LHC collider a significant rate of events with double parton scattering is expected. This will be the leading mechanism for production of two b-bbar pairs. We estimate the probability of binding two b quarks into a diquark and the probability of dressing this diquark into a b-b-ubar-dbar ISP=01+ tetraquark. Calculations shows that that this bound state of two B mesons is stable against the strong interaction and has a life time of the order of ps. We estimate that the production rate at luminosity L=0.1 events per second will be about 6 tetraquarks per hour or more.

hep-ph

A Phenomenological Estimate of the Binding Energy of Heavy Dimesons

A phenomenological estimate is derived such that the binding energies of dimesons are expressed as combinations of masses of different mesons and baryons. The estimate is almost model-independent, the only major assumptions being that the wave functions of the two light quarks in $Λ_c$, $Λ_b$ and in the $\bar{c}\bar{c}qq$ and $\bar{b}\bar{b}qq$ dimesons are very similar, and that for heavy quarks the $QQ$ interaction is half as strong as the $Q\bar{Q}$ interaction. We get $\bar{b}\bar{b}qq$ (I=0, J=1) bound by about 100 MeV and $\bar{c}\bar{c}qq$ unbound.

hep-ph

The constituent quark as a soliton in a linear sigma-model

We study a stable, soliton-like solution in the linear $σ$-model where the chiral fields are coupled to a single massless nonstrange quark. We investigate a possibility that this solution represents the constituent quark of Georgi and Manohar. We show that its properties are indeed consistent with nucleon observables. Furthermore, we derive chiral meson exchange potentials between such objects which are similar to recently used potentials in the constituent quark models.

hep-ph

Low-energy dynamics of the $γγ\toππ$ reaction

We calculate the one-quark-loop amplitude for the low energy $γγ\toππ$ collision in the context of the Nambu and Jona-Lasinio model with scalar and pseudoscalar four quark couplings to all orders in the external momenta. We show that the NJL predictions for the $γγ\toπ^+π^-$ reaction are not far from the Born amplitude, which is close to the data, and is compatible with the chiral perturbation theory estimations. We determine the corrections given by the NJL model in leading order of $1/N_c$ to the chiral loop amplitude for $γγ\toπ^0π^0$. Numerical results for the $γγ\rightarrowππ$ cross sections and for pion polarizabilities are given.

hep-ph

Counting pions in the nucleon

The number of pions in the nucleon is a theoretical concept and its value is model dependent. It is, however, a useful tool to understand the pionic contribution to several nucleon observables such as electric charge radii, magnetic moments, axial charge, pion-nucleon coupling constant, amplitudes for electroexcitation of baryon resonances and electroproduction of pions above such resonances.

hep-ph