Thu·Mar 26, 2020Thursday·March 26, 2020

1. 01*

   Joint lattice QCD - dispersion theory analysis confirms the quark-mixing top-row unitarity deficit

   Chien-Yeah Seng🇩🇪 · Xu Feng🇨🇳 · Mikhail Gorchtein🇩🇪 · Lu-Chang Jin🇺🇸

   Recently, the first ever lattice computation of the $\gamma W$-box radiative correction to the rate of the semileptonic pion decay allowed for a reduction of the theory uncertainty of that rate by a factor of $\sim 3$. A recent dispersion evaluation of the $\gamma W$-box correction on the neutron also led to a significant reduction of the theory uncertainty, but shifted the value of $V_{ud}$ extracted from the neutron and superallowed nuclear $\beta$ decay, resulting in a deficit of the CKM unitarity in the top row. A direct lattice computation of the $\gamma W$-box correction for the neutron decay would provide an independent cross-check for this result but is very challenging. Before those challenges are overcome, we propose a hybrid analysis, converting the lattice calculation on the pion to that on the neutron by a combination of dispersion theory and phenomenological input. The new prediction for the universal radiative correction to free and bound neutron $\beta$-decay reads ${\Delta }_R^V=0.02477(24)$, in excellent agreement with the dispersion theory result ${\Delta }_R^V=0.02467(22)$. Combining with other relevant information, the top-row CKM unitarity deficit persists.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2020)·148 citations
2. 02*

   Self-consistent Green's function theory for atomic nuclei

   Vittorio Somà🇫🇷

   Nuclear structure theory has recently gone through a major renewal with the development of ab initio techniques that can be applied to a large number of atomic nuclei, well beyond the light sector that had been traditionally targeted in the past. Self-consistent Green's function theory is one among these techniques. The present work aims to give an overview of the self-consistent Green's function approach for atomic nuclei, including examples of recent applications and a discussion on the perspectives for extending the method to nuclear reactions, doubly open-shell systems and heavy nuclei.

   ↳ nucl-thnucl-exphysics.chem-phFront.in Phys.(2020)·89 citations
3. 03*

   Coherent Elastic Neutrino-Nucleus Scattering with directional detectors

   M. Abdullah🇺🇸 · D. Aristizabal Sierra🇨🇱 · Bhaskar Dutta🇺🇸 · Louis E. Strigari🇺🇸

   We study the sensitivity of detectors with directional sensitivity to coherent elastic neutrino-nucleus scattering (CE$\nu$NS), and how these detectors complement measurements of the nuclear recoil energy. We consider stopped pion and reactor neutrino sources, and use gaseous helium and fluorine as examples of detector material. We generate Standard Model predictions, and compare to scenarios that include new, light vector or scalar mediators. We show that directional detectors can provide valuable additional information in discerning new physics, and we identify prominent spectral features in both the angular and the recoil energy spectrum for light mediators, even for nuclear recoil energy thresholds as high as $\sim 50$ keV. Combined with energy and timing information, directional information can play an important role in extracting new physics from CE$\nu$NS experiments.

   ↳ hep-phhep-exnucl-exnucl-th+1PRD(2020)·30 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.