We study SU(3) flavor-breaking corrections to the relation between the octet baryon masses and the nucleon-meson CP-violating interactions induced by the QCD θ¯ term. We work within the framework of ...SU(3) chiral perturbation theory and work through next-to-next-to-leading order in the SU(3) chiral expansion, which is O(mq2). At lowest order, the CP-odd couplings induced by the QCD θ¯ term are determined by mass splittings of the baryon octet, the classic result of Crewther et al. Phys. Lett. B 88, 123 (1979)PYLBAJ0370-269310.1016/0370-2693(79)90128-X. We show that for each isospin-invariant CP-violating nucleon-meson interaction there exists one relation that is respected by loop corrections up to the order we work, while other leading-order relations are violated. With these relations we extract a precise value of the pion-nucleon coupling g¯0 by using recent lattice QCD evaluations of the proton-neutron mass splitting. In addition, we derive semiprecise values for CP-violating coupling constants between heavier mesons and nucleons with ~30% uncertainty and discuss their phenomenological impact on electric dipole moments of nucleons and nuclei.
We present $\nu$DoBe, a Python tool for the computation of neutrinoless
double beta decay ($0\nu\beta\beta$) rates in terms of lepton-number-violating
operators in the Standard Model Effective Field ...Theory (SMEFT). The tool can be
used for automated calculations of $0\nu\beta\beta$ rates, electron spectra and
angular correlations for all isotopes of experimental interest, for
lepton-number-violating operators up to and including dimension 9. The tool
takes care of renormalization-group running to lower energies and provides the
matching to the low-energy effective field theory and, at lower scales, to a
chiral effective field theory description of $0\nu\beta\beta$ rates. The user
can specify different sets of nuclear matrix elements from various many-body
methods and hadronic low-energy constants. The tool can be used to quickly
generate analytical and numerical expressions for $0\nu\beta\beta$ rates and to
generate a large variety of plots. In this work, we provide examples of
possible use along with a detailed code documentation. The code can be accessed
through:
GitHub: https://github.com/OScholer/nudobe
Online User-Interface: https://nudobe.streamlit.app
Axions provide a solution to the strong CP problem and are excellent dark matter candidates. The presence of additional sources of CP violation, for example to account for the matter/antimatter ...asymmetry of the universe, can lead to CP-violating interactions between axions and Standard Model fields. In case axions form a coherent dark matter background, this leads to time-oscillating fundamental constants such as the fine-structure constant and particle masses. In this work we compare the sensitivity of various searches for CP-odd axion interactions. These include fifth-force experiments, searches for time-oscillating constants induced by axion dark matter, and direct limits from electric dipole moment experiments. We show that searches for oscillating constants can outperform fifth-force experiments in the regime of small axion masses, but, in general, do not reach the sensitivity of electric dipole moment experiments.
Charged currents are probed in low-energy precision $\beta$-decay experiments
and at high-energy colliders, both of which aim to measure or constrain signals
of beyond-the-Standard-Model physics. In ...light of future $\beta$-decay and LHC
measurements that will further explore these non-standard interactions, we
investigate what neutrinoless double-$\beta$ decay ($0\nu\beta\beta$)
experiments can tell us if a nonzero signal were to be found. Using a recently
developed effective-field-theory framework, we consider the effects that
interactions with right-handed neutrinos have on $0\nu\beta\beta$ and discuss
the range of neutrino masses that current and future $0\nu\beta\beta$
measurements can probe, assuming neutrinos are Majorana particles. For
non-standard interactions at the level suggested by recently observed hints in
$\beta$ decays, we show that next-generation $0\nu\beta\beta$ experiments can
determine the Dirac or Majorana nature of neutrinos, for sterile neutrino
masses larger than $\mathcal O(10)$ eV.
Radiative corrections are essential for an accurate determination of $V_{ud}$
from superallowed $\beta$ decays. In view of recent progress in the
single-nucleon sector, the uncertainty is dominated ...by the theoretical
description of nucleus-dependent effects, limiting the precision that can
currently be achieved for $V_{ud}$. In this work, we provide a detailed account
of the electroweak corrections to superallowed $\beta$ decays in effective
field theory (EFT), including the power counting, potential and ultrasoft
contributions, and factorization in the decay rate. We present a first
numerical evaluation of the dominant corrections in light nuclei based on
Quantum Monte Carlo methods, confirming the expectations from the EFT power
counting. Finally, we discuss strategies how to extract from data the
low-energy constants that parameterize short-distance contributions and whose
values are not predicted by the EFT. Combined with advances in ab-initio
nuclear-structure calculations, this EFT framework allows one to systematically
address the dominant uncertainty in $V_{ud}$, as illustrated in detail for the
$^{14}$O $\to$ $^{14}$N transition.
The accuracy of $V_{ud}$ determinations from superallowed $\beta$ decays
critically hinges on control over radiative corrections. Recently, substantial
progress has been made on the single-nucleon, ...universal corrections, while
nucleus-dependent effects, typically parameterized by a quantity
$\delta_\text{NS}$, are much less well constrained. Here, we lay out a program
to evaluate this correction from effective field theory (EFT), highlighting the
dominant terms as predicted by the EFT power counting. Moreover, we compare the
results to a dispersive representation of $\delta_\text{NS}$ and show that the
expected momentum scaling applies even in the case of low-lying intermediate
states. Our EFT framework paves the way towards ab-initio calculations of
$\delta_\text{NS}$ and thereby addresses the dominant uncertainty in $V_{ud}$.
Electric dipole moments of nuclei, diamagnetic atoms, and certain molecules are induced by CP-violating nuclear forces. Naive dimensional analysis predicts these forces to be dominated by long-range ...one-pion-exchange processes, with short-range forces entering only at next-to-next-to-leading order in the chiral expansion. Based on renormalization arguments we argue that a consistent picture of CP-violating nuclear forces requires a leading-order short-distance operator contributing to \({}^1S_0\)-\({}^3P_0\) transitions, due to the attractive and singular nature of the strong tensor force in the \({}^3P_0\) channel. The short-distance operator leads to \(\mathcal O(1)\) corrections to static and oscillating, relevant for axion searches, electric dipole moments. We discuss strategies how the finite part of the associated low-energy constant can be determined in the case of CP violation from the QCD theta term by the connection to charge-symmetry violation in nuclear systems.
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