The Dark Dimension and the Grand Unification of Forces

Speaker: Fengjun Xu (BIMSA)
Time & Date: 10:00-11:00am, Mar 26
Location: Room 1510

Abstract: In this talk, we start with a brief introduction on basic aspects of Swampland program. With a focus on one of the swampland conjecture-the dark dimension scenario, we show that find realizing the grand unification of gauge forces is highly constraining in this context. Without actually constructing any GUT models, we argue that the mere assumption of grand unification of forces in this scenario, together with the experimental bounds on massive replicas of the Standard Model gauge bosons, predicts an upper bound for the GUT scale, M_GUT<= 10^16 GeV. Combined with the experimental bound on the proton lifetime, this predicts that the X gauge boson mediating proton decay is a 5d solitonic string of Planckian tension stretched across a length scale L∼(1−10 TeV)^-1 ending on gauge branes of the same diameter ∼L. This leads to a mass of M_X∼10^15−10^16 GeV. In particular assuming grand unification in the dark dimension scenario results in a tower of Kaluza-Klein excitations of Standard Model gauge bosons on the gauge branes in the 1-10 TeV range. This suggests that the diameter/separation L of the gauge branes correlates with both the weak scale ∼1/L near a TeV {\it and} the GUT scale ∼M^2_5L at 10^16 GeV.