Nonlinear isotope-shift effects in Be-like, B-like, and C-like argon

Abstract

Violation of linearity of the King plot is investigated for a chain of partially stripped argon isotopes. The nonlinearity originates within the Standard Model from subtle contributions to the isotope shifts from nextto-leading order effects, which have never been systematically studied so far. In light atoms these nonlinear effects are dominated by the quadratic nuclear recoil (∝ 1/M 2 where M is the nuclear mass). Large-scale relativistic calculations of the linear and quadratic mass shift and the field shift are performed for the 2P finestructure transitions in Be-like, B-like, and C-like argon ions. Nonlinearities of the King plots from 5 to 30 kHz are found, which is four orders of magnitude larger than previous estimates in comparable systems. Accurate calculations of these effects are vital for identification of possible nonlinearities originating from physics beyond the Standard Model.

Evidence for Nonlinear Isotope Shift in Yb+ Search for New Boson

“…Characterizing the nonlinearities arising from within the SM can provide new information about the nucleus [88], especially in combination with improved electronicstructure calculations. On the other hand, if evidence for a new boson should emerge from the improved measurements, it can be independently verified by performing similar measurements on other atomic species [10], such as Ca=Ca þ [13,89], Sr=Sr þ [12,14], Nd þ [90], or on highly charged ions [91][92][93][94], as well as on molecules like Sr 2 [95]. Unstable isotopes (e.g., 166 Yb with a half-life of ∼2.4 days) can be used to increase the number of points in the King Plot, providing strong further constraints on the origin of the nonlinearity.…”

Radiative and photon-exchange corrections to New Physics contributions to energy levels in few-electron ions

“…Such nonlinear King data can be a sign of NP, but it was shown in Refs. [15,27,28] that carefully accounting for SM sources of King nonlinearity is important for a reliable interpretation of isotope shift data on few-electron ions. In the present work, the focus is on computing the NP correction to the energy levels of few-electron ions with improved accuracy.…”

Nuclear charge radii of Na isotopes: A tale of two theories

“…where m e is the electron mass [21][22][23][24][25][26][27]. However, accurate calculations of K SMS are extremely challenging for systems with more than six elec-trons [14,[28][29][30][31][32][33]. When given, the reported K SMS uncertainties in many-electron systems are typically larger than 10% [11,12,[34][35][36][37][38], thus limiting the effectiveness of comparisons between experimental charge radii with those calculated using nuclear theory.…”