Zahra Asmaee on her presentation:
Understanding the structure of the quantum chromodynamics (QCD) vacuum is essential for explaining the properties of the strong nuclear force. However, due to the non-Abelian nature of QCD, computational methods that have been successful in other areas of physics are not efficient in the low-energy regime.
After introducing the challenging problem of confinement, one of the most intriguing and unsolved issues in particle physics, we will study the quantum chromodynamics (QCD) vacuum using the center vortex model. In this model, the vacuum is assumed to be filled with vortices, whose condensation is responsible for confinement. Inspired by lattice gauge theory and by rewriting the formalism within continuum theory, we will demonstrate, using both direct and indirect methods, that under an appropriate singular gauge transformation, vortices and chains emerge in the continuum limit in the vacuum. In the direct method, after applying a center gauge transformation and center projection, we will demonstrate that the SU(2) gauge theory reduces to a gauge theory that includes vortices. In the indirect method, in addition to the center gauge transformation and center projection, an intermediate step is introduced, called the Abelian gauge transformation and Abelian projection. As a result, a chain of monopoles and vortices emerges in the theory. After applying appropriate gauge transformations to the three SU(2) subgroups, rewriting the relations within the framework of the local color frame, and considering that topological defects in these subgroups are not independent of each other, we will investigate the topological defects and the Lagrangian in the SU(3) gauge group. Next, we will study the relationship between the defects of the three SU(2) subgroups and the SU(3) gauge group, as well as the interaction of topological defects, by comparing these results with the Cho field decomposition. Finally, we obtain the area law by calculating the expectation value of the Wilson loop for the SU(2) gauge group in three-dimensional Euclidean spacetime, using the effective partition function for an ensemble of vortices. This indicates a linear behavior of the confinement potential. We then use the area law to determine the string tension in terms of the intrinsic properties of the vortices and the parameter describing the interaction strength between them. The results are consistent with those obtained from lattice gauge theory. In addition, we will show that the repulsive force between vortices increases with temperature. This behavior suggests an approach to the deconfinement regime.
Mohadeseh on her presentation:
I will present a paper that investigates CP violation in the weak decay of bottom hadrons (B mesons) through theoretical analysis and mathematical derivations. It highlights the interplay between CP symmetry breaking and quark-level contributions, emphasizing both short-range and long-range interactions.
The study provides a robust foundation for understanding CP violation phenomena in B meson decays and suggests the need for improving measurement precision to validate theoretical models and explore new physics.
No responses yet