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Your search keyword '"Shafi, Qaisar"' showing total 2 results
Start Over Author "Shafi, Qaisar" Topic symmetry breaking Publication Year Range Last 3 years
2 results on '"Shafi, Qaisar"'

1. Composite topological structures in SO(10).

Author

Lazarides, George, Shafi, Qaisar, and Tiwari, Amit

Subjects
*COMPOSITE structures, *MAXIMAL subgroups, *GRAVITATIONAL waves, *SYMMETRY breaking, *PHASE transitions
Abstract

We explore a variety of composite topological structures that arise from the spontaneous breaking of SO(10) to SU(3)c× U(1)em via one of its maximal subgroups SU(5) × U(1)χ, SU(4)c× SU(2)L× SU(2)R, and SU(5) × U(1)X (also known as flipped SU(5)). They include i) a network of ℤ strings which develop monopoles and turn into necklaces with the structure of ℤ2 strings, ii) dumbbells connecting two different types of monopoles, or monopoles and antimonpoles, iii) starfish-like configurations, iv) polypole configurations, and v) walls bounded by a necklace. We display these structures both before and after the electroweak breaking. The appearance of these composite structures in the early universe and their astrophysical implications including gravitational wave emission would depend on the symmetry breaking patterns and scales, and the nature of the associated phase transitions. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Pseudo-Goldstone dark matter in SO(10).

Author

Nobuchika Okada, Raut, Digesh, Shafi, Qaisar, and Thapa, Anil

Subjects
*DARK matter, *LARGE Hadron Collider, *NAMBU-Goldstone bosons, *STANDARD model (Nuclear physics), *SYMMETRY breaking, *MAGIC angle spinning
Abstract

We propose a pseudo-Goldstone boson dark matter (pGDM) particle in SO(10) grand unified theory (GUT). Due to its Goldstone nature, this pGDM evades the direct DM detection experiments which, otherwise, severely constrain the parameter space of DM models. In SO(10), the pGDM is embedded as a linear combination of the Standard Model (SM) singlet scalars in 16H and ̅126H representations. We consider two scenarios for the intermediate route of SO(10) symmetry breaking (SB) to the SM: SU(5)×U(1)X and Pati-Salam the SU(4)c×SU(2)L×SU(2)R(4-2-2) gauge groups. The vacuum expectation value of ̅126H, which triggers the breaking of U(1)X and 4-2-2 symmetry in the two scenarios, respectively, determines the pGDM lifetime whose astrophysical lower bound provides one of the most stringent constraints. For the 4-2-2 route to SO(10), the successful SM gauge coupling unification requires the 4-2-2 breaking scale to be O(1011) GeV, and most of the parameter space is excluded. For the SU(5)×U(1)X route, on the other hand, the U(1)X breaking scale can be significantly higher, and a wide range of the parameter space is allowed. Furthermore, the proton lifetime in the SU(5) case is predicted to be 4.53×1034 years, which lies well within the sensitivity reach of the Hyper-Kamiokande experiment. We also examine the constraints on the model parameter space from the Large Hadron Collider and the indirect DM search by Fermi-LAT and MAGIC experiments. [ABSTRACT FROM AUTHOR]

Published
2021
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