arXiv subjects

Z. Xin

Publications and source records attributed to Z. Xin.

5 recordsLinked to original sources

arXiv2022

Inspection of the detection cross section dependence of the Gallium Anomaly

We discuss in detail the dependence of the Gallium Anomaly on the detection cross section. We provide updated values of the size of the Gallium Anomaly and find that its significance is larger than about $5\sigma$ for all the detection cross section models. We discuss the dependence of the Gallium Anomaly on the assumed value of the half life of ${}^{71}\text{Ge}$, which determines the cross sections of the transitions from the ground state of ${}^{71}\text{Ga}$ to the ground state of ${}^{71}\text{Ge}$. We show that a value of the ${}^{71}\text{Ge}$ half life which is larger than the standard one can reduce or even solve the Gallium Anomaly. Considering the short-baseline neutrino oscillation interpretation of the Gallium Anomaly, we show that a value of the ${}^{71}\text{Ge}$ half life which is larger than the standard one can reduce the tension with the results of other experiments. Since the standard value of the ${}^{71}\text{Ge}$ half life was measured in 1985, we advocate the importance of new measurements with modern technique and apparatus for a better assessment of the Gallium Anomaly.

hep-ph↗

arXiv2022

Measuring the Dust Masses of Protoplanetary Disks in Lupus with ALMA: Evidence that Disks can be Optically Thick at 3 mm

Accurate disk mass measurements are necessary to constrain disk evolution and the timescale of planet formation, but such measurements are difficult to make and are very dependent on assumptions. Here we look at the assumption that the disk is optically thin at radio wavelengths and the effect of this assumption on measurements of disk dust mass. We model the optical to radio spectral energy distributions (SEDs) of 41 protoplanetary disks located in the young (~1-3 Myr old) Lupus star-forming region, including 0.89 mm, 1.33 mm, and 3 mm flux densities when available. We measure disk dust masses that are ~1.5-6 times higher than when using the commonly adopted disk dust mass equation under the assumption of optically thin emission in the (sub-)millimeter. The cause of this discrepancy is that most disks are optically thick at millimeter wavelengths, even up to 3 mm, demonstrating that observations at longer wavelengths are needed to trace the fully optically thin emission of disks.

astro-ph.SR↗

arXiv2022

Gallium Anomaly: Critical View from the Global Picture of $\nu_{e}$ and $\bar\nu_{e}$ Disappearance

The significance of the Gallium Anomaly, from the BEST, GALLEX, and SAGE radioactive source experiments, is quantified using different theoretical calculations of the neutrino detection cross section, and its explanation due to neutrino oscillations is compared with the bounds from the analyses of reactor rate and spectral ratio data, $\beta$-decay data, and solar neutrino data. In the 3+1 active-sterile neutrino mixing scheme, the Gallium Anomaly is in strong tension with the individual and combined bounds of these data sets. In the combined scenario with all available data, the parameter goodness of fit is below 0.042%, corresponding to a severe tension of 4-5$\sigma$, or stronger. Therefore, we conclude that one should pursue other possible solutions beyond short-baseline oscillations for the Gallium Anomaly. We also present a new global fit of $\nu_e$ and $\bar\nu_e$ disappearance data, showing that there is a 2.6-3.3$\sigma$ preference in favor of short-baseline oscillations, which is driven by an updated analysis of reactor spectral ratio data.

hep-ph↗

arXiv2022

White Paper on Light Sterile Neutrino Searches and Related Phenomenology

This white paper provides a comprehensive review of our present understanding of experimental neutrino anomalies that remain unresolved, charting the progress achieved over the last decade at the experimental and phenomenological level, and sets the stage for future programmatic prospects in addressing those anomalies. It is purposed to serve as a guiding and motivational "encyclopedic" reference, with emphasis on needs and options for future exploration that may lead to the ultimate resolution of the anomalies. We see the main experimental, analysis, and theory-driven thrusts that will be essential to achieving this goal being: 1) Cover all anomaly sectors -- given the unresolved nature of all four canonical anomalies, it is imperative to support all pillars of a diverse experimental portfolio, source, reactor, decay-at-rest, decay-in-flight, and other methods/sources, to provide complementary probes of and increased precision for new physics explanations; 2) Pursue diverse signatures -- it is imperative that experiments make design and analysis choices that maximize sensitivity to as broad an array of these potential new physics signatures as possible; 3) Deepen theoretical engagement -- priority in the theory community should be placed on development of standard and beyond standard models relevant to all four short-baseline anomalies and the development of tools for efficient tests of these models with existing and future experimental datasets; 4) Openly share data -- Fluid communication between the experimental and theory communities will be required, which implies that both experimental data releases and theoretical calculations should be publicly available; and 5) Apply robust analysis techniques -- Appropriate statistical treatment is crucial to assess the compatibility of data sets within the context of any given model.

hep-ex↗

arXiv2021

Reactor antineutrino anomaly in light of recent flux model refinements

We study the status of the reactor antineutrino anomaly in light of recent reactor flux models obtained with the conversion and summation methods. We present a new improved calculation of the IBD yields of the standard Huber-Mueller (HM) model and those of the new models. We show that the reactor rates and the fuel evolution data are consistent with the predictions of the Kurchatov Institute (KI) conversion model and with those of the Estienne-Fallot (EF) summation model, leading to a plausible robust demise of the reactor antineutrino anomaly. We show that the results of several goodness of fit tests favor the KI and EF models over other models that we considered. We also discuss the implications of the new reactor flux models for short-baseline neutrino oscillations due to active-sterile oscillations. We show that reactor data give upper bounds on active-sterile neutrino mixing that are not very different for the reactor flux models under consideration and are in tension with the large mixing required by the Gallium anomaly that has been refreshed by the recent results of the BEST experiment.

hep-ph↗