1,721,039 research outputs found
Muon and electron g - 2and proton and cesium weak charges implications on dark Zd models
Full text linkTheories beyond the standard model involving a sub-GeV-scale vector mediator have been largely studied as a possible explanation of the experimental values of the muon and electron anomalous magnetic moments. Motivated by the recent determination of the anomalous muon magnetic moment performed at Fermilab, we derive the constraints on such a model obtained from the magnetic moment determinations and the measurements of the proton and cesium weak charge, , performed at low-energy transfer. In order to do so, we revisit the determination of the cesium from the atomic parity violation experiment, which depends critically on the value of the average neutron rms radius of , by determining the latter from a practically model-independent extrapolation from the recent average neutron rms radius of performed by the PREX-2 Collaboration. From a combined fit of all the aforementioned experimental results, we obtain rather precise limits on the mass and the kinetic mixing parameter of the boson, namely and , when marginalizing over the mass mixing parameter
On the impact of the Migdal effect in reactor CEνNS experiments
Full text linkThe search for coherent elastic neutrino nucleus scattering (CEνNS) using reactor antineutrinos represents a formidable experimental challenge, recently boosted by the observation of such a process at the Dresden-II reactor site using a germanium detector. This observation relies on an unexpected enhancement at low energies of the measured quenching factor with respect to the theoretical Lindhard model prediction, which implies an extra observable ionization signal produced after the nuclear recoil. A possible explanation for this additional contribution could be provided by the so-called Migdal effect, which however has never been observed. Here, we study in detail the impact of the Migdal contribution to the standard CEνNS signal calculated with the Lindhard quenching factor, finding that the former is completely negligible for observed energies below ∼0.3keV where the signal is detectable, and thus unable to provide any contribution to CEνNS searches in this energy regime. To this purpose, we compare different formalisms used to describe the Migdal effect that intriguingly show a perfect agreement, making our findings robust
Constraints on light vector mediators through coherent elastic neutrino nucleus scattering data from COHERENT
No full textWe present new constraints on three different models, the so-called universal, B − L and Lμ− Lτ models, involving a yet to be observed light vector Z′ mediator, by exploiting the recent observation of coherent elastic neutrino-nucleus scattering (CEνNS) in argon and cesium-iodide performed by the COHERENT Collaboration. We compare the results obtained from a combination of the above data sets with the limits derived from searches in fixed target, accelerator, solar neutrino and reactor CEνNS experiments, and with the parameter region that could explain the anomalous magnetic moment of the muon. We show that for the universal and the B − L models, the COHERENT data allow us to put stringent limits in the light vector mediator mass, MZ′, and coupling, gZ′, parameter space
Nuclear neutron radius and weak mixing angle measurements from latest COHERENT CsI and atomic parity violation Cs data
Full text linkThe COHERENT collaboration observed coherent elastic neutrino nucleus scattering using a 14.6 kg cesium iodide (CsI) detector in 2017 and recently published the updated results before decommissioning the detector. Here, we present the legacy determination of the weak mixing angle and of the average neutron rms radius of Cs-133 and I-127 obtained with the full CsI dataset, also exploiting the combination with the atomic parity violation (APV) experimental result, that allows us to achieve a precision as low as similar to 4.5% and to disentangle the contributions of the Cs-133 and I-127 nuclei. Interestingly, we show that the COHERENT CsI data show a 6 sigma evidence of the nuclear structure suppression of the full coherence. Moreover, we derive a data-driven APV+COHERENT measurement of the low-energy weak mixing angle with a percent uncertainty, independent of the value of the average neutron rms radius of Cs-133 and I-127, that is allowed to vary freely in the fit. Additionally, we extensively discuss the impact of using two different determinations of the theoretical parity non-conserving amplitude in the APV fit. Our findings show that the particular choice can make a significant difference, up to 6.5% on R-n(Cs) and 11% on the weak mixing angle. Finally, in light of the recent announcement of a future deployment of a 10 kg and a similar to 700 kg cryogenic CsI detectors, we provide future prospects for these measurements, comparing them with other competitive experiments that are foreseen in the near future
Incorporating the weak mixing angle dependence to reconcile the neutron skin measurement on Pb208 by PREX-II
Full text linkThe only available electroweak measurement of the 208Pb neutron skin Rnp, performed by the PREX-II Collaboration through polarized electron-lead scattering, shows a mild tension with respect to both the theoretical nuclear-model predictions and a host of measurements. However, the dependence on the weak mixing angle should be incorporated in the calculation, since its low-energy value is experimentally poorly known. We first repeat the PREX-II analysis confirming their measurement by fixing the weak mixing angle to its standard model value. Then, we show the explicit dependence of the PREX-II measurement on the weak mixing angle, obtaining that it is fully degenerate with the neutron skin. To break this degeneracy, we exploit the weak mixing angle measurement from atomic parity violation on lead, obtaining a slightly thinner neutron skin but with about doubled uncertainties, possibly easing the PREX tension. Relying on the theoretical prediction, Rth np ≈ 0.13–0.19 fm, and using it as a prior in the fit, we find a weak mixing angle value about 1.2σ smaller than the standard model prediction. Thus, we suggest a possible solution of the PREX-II tension by showing that, considering its underlying dependence on the weak mixing angle, the PREX-II neutron skin determination could be in agreement with the other available measurements and predictions if the weak mixing angle at the proper energy scale is smaller than the standard model prediction
New constraint on neutrino magnetic moment and neutrino millicharge from LUX-ZEPLIN dark matter search results
Full text linkElastic neutrino-electron scattering represents a powerful tool to investigate key neutrino properties. In view of the recent results released by the LUX-ZEPLIN collaboration, we provide a first determination of the limits achievable on the neutrino magnetic moment and neutrino millicharge, whose effect becomes non-negligible in some beyond the Standard Model theories. In this context, we evaluate and discuss the impact of different approximations to describe the neutrino interaction with atomic electrons. The new LUX-ZEPLIN data allows us to set a very competitive limit on the neutrino magnetic moment when compared to the other laboratory bounds, namely mu effv < 1.1 x 10-11 mu B at 90% C.L., which improves by a factor of 2.5 the Borexino collaboration limit and represents the second best world limit after the recent XENONnT result. Moreover, exploiting the so-called equivalent photon approximation, we obtain the most stringent limit on the neutrino millicharge, namely Iqeffv I < 1.5 x 10-13e0 at 90% C.L., which represents a great improvement with respect to the previous laboratory bounds
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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