# YTF 20

15-16 December 2020
Centre for Particle Theory, Durham
Europe/London timezone

## Non-SUSY String Phenomenology from Z$_2\times$Z$_2$ Heterotic Orbifolds

16 Dec 2020, 12:00
30m
Teams (Centre for Particle Theory, Durham)

### Teams

#### Centre for Particle Theory, Durham

IPPP & Dept. Mathematical Sciences Durham University South Road Durham DH1 3LE

### Speaker

Benjamin Percival (Liverpool University)

### Description

We explore the space of non-SUSY string models via two distinct routes: the tachyon-free O(16)$\times$O(16) heterotic string in 10D and a tachyonic 10D heterotic string. We classify 4D Z$_2\times$Z$_2$ orbifolds descending from these two starting points in the free fermionic construction. Having found a potentially stable Standard-like model descending from the tachyonic 10D vacuum in arXiv:1912.00061, the approach of taking these models on equal footing with the non-tachyonic 10D models is justified provided that the tachyonic states are projected out in the four dimensional models. In both classes of models we find examples of Type 0 and Type 0bar models, i.e. models free of fermionic massless states and models free of twisted massless bosons, respectively. Moving beyond these extreme configurations we seek to classify tachyon-free vacua according to standard phenomenological criteria in both classes of model, where an SO(10) GUT is broken to the Pati-Salam subgroup. An analysis of the cosmological constant and misaligned supersymmetry in the two classes of models finds notable vacua in both cases in which N$_b$=N$_f$ at the massless level.

Will you be pre-recording your talk? No 15-25 minutes Yes Yes

### Primary author

Benjamin Percival (Liverpool University)

### Co-authors

Mr Viktor Matyas (University of Liverpool) Prof. Alon Faraggi (University of Liverpool)

### Presentation Materials

 Ben's talk.mp4 StringPhenoSeminarTalk (3).pdf