1,966 research outputs found
The space-time torsion in the context of the Exact Foldy-Wouthuysen Transformation for a Dirac fermion
In this work we focus our attention in the inconsistency that appears when
the Semi-Exact Foldy-Wouthuysen transformation for the Dirac field interacting
with space-time torsion field is performed. In order to solve this problem, we
present a new involution operator that makes possible to perform the exact
transformation when torsion field is present. Such operator has a structure,
well known in the literature, composed of the product of an operator that acts
in the matrices space and another one that acts in the function space. We also
present the bound state of this theory and discuss the possible experimental
analysis
Fully-heavy tetraquark production by interactions in hadronic collisions at the LHC
We investigate the production of the fully - heavy tetraquark states
in the interactions present in proton-proton, proton-nucleus
and nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC). We
focus on the () subprocess, mediated by the resonance in the
- channel, and present predictions for the hadronic cross sections considering
the kinematical ranges probed by the ALICE and LHCb Collaborations. Our results
demonstrate that the experimental study of this process is feasible and can be
used to investigate the existence and properties of the and
states.Comment: 5 pages, 2 figures, 2 tables. arXiv admin note: substantial text
overlap with arXiv:1809.0812
Abaqus UGENS subroutine for nonlinear analysis of periodic panels
This report describes an Abaqus UGENS subroutine for geometric and material nonlinear analysis of periodic panels using the first-order shear deformation theory. The structure is modelled with shell elements, as one layer of equivalent mechanical properties. The subroutine modifies the stiffness matrix of each shell element of the mesh separately based on its strain state. It relies on pre-computed stiffness curves that define the ABCD stiffness matrix of a unit cell. By looking at combinations of force and strain, the code interpolates the stiffness curves to calculate equivalent nonlinear stiffness. Complex stress states with different types of nonlinearity occurring simultaneously in the structure can be described. The examples show that the subroutine can deal with nonlinearities such as global buckling, local buckling and post-yield response with good accuracy and low computational cost compared to conventional FEM. The report includes the necessary information to set up the subroutine, including selection and compatibility of software and packages and input file preparation. Web-core sandwich panels are used as example throughout the report; the same principles are valid for any periodic structure. The full implementation is given in Appendix
Exclusive plus jet associated production in ultraperipheral collisions
The study of exclusive processes in ultraperipheral collisions at the Large
Hadron Collider (LHC) has allowed us to test several aspects of the Standard
Model and to search for New Physics. In this letter, we investigate the
possibility of using these processes to improve our understanding of the
quarkonium production mechanism through the study of the exclusive
plus jet associate production in ultraperipheral collisions. We estimate
the transverse - momentum and rapidity distributions considering that the
() subprocess is
described by the Non - Relativistic QCD (NRQCD) formalism and present
predictions for the rapidity ranges covered by central and forward detectors.
The experimental separation of these events is discussed and the results
indicate that a future experimental analysis is, in principle, feasible in
future runs of the LHC and the Future Circular Collider (FCC).Comment: 9 pages, 4 figures, 2 table
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