Searching for heavy leptophilic Z′: from lepton colliders to gravitational waves

• Published in: The journal of high energy physics Vol. 2023; no. 12; pp. 11 - 51
• Main Authors: Dasgupta, Arnab, Dev, P. S. Bhupal, Han, Tao, Padhan, Rojalin, Wang, Si, Xie, Keping
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2023; Springer Nature B.V; SpringerOpen
• Subjects: Bosons; Broken symmetry; Classical and Quantum Gravitation; Elementary Particles; Gravitational waves; High energy physics; Leptons; New Gauge Interactions; Observatories; Phase transitions; Phase Transitions in the Early Universe; Phenomenology; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; Sensitivity; String Theory; Supercooling; New Gauge Interactions; Phase Transitions in the Early Universe
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP12(2023)011

A
bstract
We study the phenomenology of leptophilic
Z
′ gauge bosons at the future high-energy
e
+
e
−
and
μ
+
μ
−
colliders, as well as at the gravitational wave observatories. The leptophilic
Z
′ model, although well-motivated, remains largely unconstrained from current low-energy and collider searches for
Z
′ masses above
O
(100 GeV), thus providing a unique opportunity for future lepton colliders. Taking
U
1
L
α
−
L
β
(
α
,
β
=
e
,
μ
,
τ
) models as concrete examples, we show that future
e
+
e
−
and
μ
+
μ
−
colliders with multi-TeV center-of-mass energies provide unprecedented sensitivity to heavy leptophilic
Z
′ bosons. Moreover, if these U(1) models are classically scale-invariant, the phase transition at the U(1) symmetry-breaking scale tends to be strongly first-order with ultra-supercooling, and leads to observable stochastic gravitational wave signatures. We find that the future sensitivity of gravitational wave observatories, such as advanced LIGO-VIRGO and Cosmic Explorer, can be complementary to the collider experiments, probing higher
Z
′ masses up to
O
(10
4
TeV), while being consistent with naturalness and perturbativity considerations.