IR/UV mixing, towers of species and swampland conjectures

A bstract By applying the Covariant Entropy Bound (CEB) to an EFT in a box of size 1 / ΛIR one obtains that UV and IR cut-offs are necessarily correlated. We argue theory Quantum Gravity (QG) should identify cutoff with ‘species scale’, give general algorithm calculate it case multiple towers becoming light. One then upper bound on characteristic mass scale tower terms cut-off, given by M ≲ $$ {\left({\Lambda}_{\mathrm{IR}}\right)}^{2{\alpha}_D} Λ IR 2 α D Planck units, α D = ( − 2 + p )/2 1), where depends density states. Identifying cut-off (non-vanishing) curvature AdS reproduces statement Distance Conjecture (ADC), also giving explicit lower for exponent. In particular, we find CEB implies ≥ 1/2 any dimension if there is single KK tower, both dS vacua. However values < allowed particle or has string component. consider CKN constraint coming from avoiding gravitational collapse which further requires 1/ lightest tower. analyse DGKT-CFI class Type IIA orientifold models show below species scale, so careful analysis how ADC defined needed. this obey but do not saturate CEB. The UV/IR constraints found apply comment possible applications these ideas Swampland conjecture as well observed phase universe.