Exotic spin-dependent interactions through unparticle exchange

• Published in: The journal of high energy physics Vol. 2024; no. 1; pp. 83 - 21
• Main Authors: Wu, L. Y., Zhang, K. Y., Yan, H.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 16-01-2024; Springer Nature B.V; SpringerOpen
• Subjects: Axions and ALPs; Classical and Quantum Gravitation; Constraints; Couplings; Elementary Particles; Fermions; High energy physics; Measurement methods; New Light Particles; Parity; Particle physics; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; Specific BSM Phenomenology; String Theory; New Light Particles; Axions and ALPs; Specific BSM Phenomenology
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP01(2024)083

A
bstract
The potential discovery of unparticles could have far-reaching implications for particle physics and cosmology. For over a decade, high-energy physicists have extensively studied the effects of unparticles. In this study, we derive six types of nonrelativistic potentials between fermions induced by unparticle exchange in coordinate space. We consider all possible combinations of scalar, pseudo-scalar, vector, and axial-vector couplings to explore the full range of possibilities. Previous studies have only examined scalar-scalar (SS), pseudoscalar-pseudoscalar (PP), vector-vector (VV), and axial-axial-vector (AA) type interactions, which are all parity even. We propose SP and VA interactions to extend our understanding of unparticle physics, noting that parity conservation is not always guaranteed in modern physics. We explore the possibilities of detecting unparticles through the long-range interactions they may mediate with ordinary matter. Dedicated experiments using precision measurement methods can be employed to search for such interactions. We discuss the properties of these potentials and estimate constraints on their coupling constants based on existing experimental data. Our findings indicate that for some particular values of the scaling dimension
d
U
, the coupling between scalar or vector unparticles and fermions is constrained by several orders of magnitude more tightly than the previous limits. The underlying reason for this improvement is analyzed. Limits are also set on the newly proposed SP and VA interactions for continuous
d
U
values, allowing the exploration of the
d
U
dependence of the constraints. It turns out that the bounds exhibit an exponential decay trend with the increasing
d
U
.