Journal Club

Seminar Room

If you want to propose a paper, you can contact Supratim Das Bakshi (sdb AT

Tuesday 8th of March, 2022

Floccinaucinihilipilification: Semisimple extensions of the Standard Model gauge algebra

We show how one may classify all semisimple algebras containing the $\mathfrak{su}(3)\oplus \mathfrak{su}(2) \oplus \mathfrak{u}(1)$ symmetry of the Standard Model and acting on some given matter sector, enabling theories beyond the Standard Model with unification (partial or total) of symmetries (gauge or global) to be catalogued. With just a single generation of Standard Model fermions plus a singlet neutrino, the only {gauge} symmetries correspond to the well-known algebras $\mathfrak{su}(5),\mathfrak{so}(10),$ and $\mathfrak{su}(4)\oplus \mathfrak{su}(2) \oplus \mathfrak{su}(2)$, but with two or more generations a limited number of exotic symmetries mixing flavour, colour, and electroweak degrees of freedom become possible. We provide a complete catalogue in the case of 3 generations or fewer and outline how our method generalizes to cases with additional matter.
Comments: 13 pages. v2: version accepted for publication
Subjects: High Energy Physics - Theory (hep-th); High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:2104.14555 [hep-th]
  (or arXiv:2104.14555v2 [hep-th] for this version)
Journal reference: Phys. Rev. D 104, 035035 (2021)
Related DOI:

Submission history

From: Joseph Tooby-Smith [view email
[v1] Thu, 29 Apr 2021 17:59:05 UTC (371 KB)
[v2] Wed, 14 Jul 2021 06:34:30 UTC (377 KB)

presented by Renato


Towards a Model of Quarks and Leptons

We propose an extra-dimension framework on the orbifold $S^1/Z_2$ for understanding the origin of the fermion mass and mixing hierarchies. Introducing the flavor symmetry $G_F(=${\it non-Abelian}$\times${\it Abelian}) as well as the extra gauged $U(1)$ symmetries through the bulk, we regard the $SU(2)$ singlet and doublet fermions in the Standard Model (SM) to be localized at the separate 3-branes and let the extra $SU(2)$ singlet flavored fermions in the bulk couple to the SM fermions at the 3-branes. The extra $U(1)$ symmetries satisfy the $U(1)$ gravitational anomaly-free condition, playing a crucial role in achieving the desirable fermion mass and mixing hierarchies and making the flavored axion naturally light.
The singlet scalar fields, the flavon fields, are responsible for the spontaneous breaking of $G_F$ on the two 3-branes, while the $SU(2)$ singlet flavored fermions are integrated out to give rise to the effective Yukawa couplings for the SM fermions, endowed with the information of $G_F$ breaking in the two sectors. The flavored axion from the PQ symmetry is also proposed for solving the strong CP problem and being a dark matter candidate in our model.
Comments: 7 pages, 3 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:2112.13392 [hep-ph]
  (or arXiv:2112.13392v1 [hep-ph] for this version)

Submission history

From: Y.H Ahn [view email]
[v1] Sun, 26 Dec 2021 15:11:34 UTC (183 KB)

presented by Álvaro