Can the FCC-hh prove the B-L gauge symmetry?

Abstract

We present a phenomenological study of the discovery potential at the FCC-hh for a new heavy neutral vector boson,

, predicted by the

$$U(1)_{B-L}$$ U ( 1 ) B - L

gauge symmetry. Focusing on the parameter space currently not excluded by Large Hadron Collider data, we analyze the dilepton production channel

$$p p \rightarrow Z^{\prime } \rightarrow l^{+} l^{-}$$ p p → Z ′ → l + l -

(

$$l^{\pm } = e^{\pm }, \mu ^{\pm }$$ l ± = e ± , μ ±

) at a center-of-mass energy of

$$\sqrt{s} = 100$$ s = 100

 TeV. Full Monte Carlo simulations were performed for different (

$$M_{Z'}$$ M Z ′

,

$$g_{B-L}$$ g B - L

) BSM scenarios and relevant Standard Model backgrounds (including irreducible Drell-Yan, diboson, single top-quark and top-quark pair productions), identifying optimal kinematic selection cuts to guide future searches for this type of resonance. We estimate the FCC-hh reach for an integrated luminosity of

$$\mathcal {L}_{int}$$ L int

= 30 

$$ab^{-1}$$ a b - 1

. Our results demonstrate that the FCC-hh at full operation can exclude

$$Z^{\prime }$$ Z ′

masses up to

$$\sim $$ ∼

50 TeV with 95% C.L. for couplings of

$$g_{B-L} \sim 1$$ g B - L ∼ 1

, and up to

$$\sim $$ ∼

30 TeV for

$$g_{B-L} \sim 0.1$$ g B - L ∼ 0.1

. We find the kinematic cuts that optimize the signal over background ratio and achieve a

$$5\sigma $$ 5 σ

signal up to

$$Z^{\prime }$$ Z ′

masses of

$$\sim $$ ∼

40 TeV. These findings highlight the FCC-hh potential to uncover new physics signals in the high-mass regime.