Abstract
A neutrino mass model is suggested within an
$$SU(4)\otimes U(1)$$
S
U
(
4
)
⊗
U
(
1
)
-electroweak theory. The smallness of neutrino masses can be guaranteed by a seesaw mechanism realized ...through Yukawa couplings to a scalar
SU
(4)-decuplet. In this scheme the light active neutrinos are accompanied by heavy neutrinos, which may have masses at different scales, including those within eV–MeV scales investigated quite intensively in both particle physics and astrophysics/cosmology. The flavour neutrinos are superpositions of light neutrinos and a small fraction of heavy neutrinos with the mixing to be determined by the model’s parameters (Yukawa coupling coefficients or symmetry breaking scales). The distribution shape of the Yukawa couplings can be visualized via a model-independent distribution of the neutrino mass matrix elements derived by using the current experimental data. The absolute values of these Yukawa couplings are able to be determined if the symmetry breaking scales are known, and vice versa. With reference to several current and near future experiments, detectable bounds of these heavy neutrinos at different mass scales are discussed and estimated.
A neutrino mass model is suggested within an
S
U
(
4
)
⊗
U
(
1
)
-electroweak theory. The smallness of neutrino masses can be guaranteed by a seesaw mechanism realized through Yukawa couplings to a ...scalar
SU
(4)-decuplet. In this scheme the light active neutrinos are accompanied by heavy neutrinos, which may have masses at different scales, including those within eV–MeV scales investigated quite intensively in both particle physics and astrophysics/cosmology. The flavour neutrinos are superpositions of light neutrinos and a small fraction of heavy neutrinos with the mixing to be determined by the model’s parameters (Yukawa coupling coefficients or symmetry breaking scales). The distribution shape of the Yukawa couplings can be visualized via a model-independent distribution of the neutrino mass matrix elements derived by using the current experimental data. The absolute values of these Yukawa couplings are able to be determined if the symmetry breaking scales are known, and vice versa. With reference to several current and near future experiments, detectable bounds of these heavy neutrinos at different mass scales are discussed and estimated.
Measurement of the Λ c + Lifetime Abudinén, F.; Aggarwal, L.; Aihara, H. ...
Physical review letters,
02/2023, Letnik:
130, Številka:
7
Journal Article
Recenzirano
Odprti dostop
An absolute measurement of the $\Lambda^{+}_c$ lifetime is reported using $\Lambda_c^+\rightarrow pK^-\pi^+$ decays in events reconstructed from data collected by the Belle II experiment at the ...SuperKEKB asymmetric-energy electron-positron collider. The total integrated luminosity of the data sample, which was collected at center-of-mass energies at or near the $\Upsilon(4S)$ resonance, is $207.2~\mbox{fb}^{-1}$. The result, $\tau(\Lambda^{+}_c) = 203.20 \pm 0.89 \,\mathrm{(stat)} \pm 0.77 \,\mathrm{(syst)}$ fs, is the most precise measurement to date and is consistent with previous determinations.
We report a measurement of the $C\!P$-violating parameters $A$ and $S$ in $B^{0}\to K_{S}^{0} \pi^{0}$ decays at Belle II using a sample of $387\times 10^{6}$ $B\bar{B}$ events recorded in ...$e^{+}e^{-}$ collisions at a center-of-mass energy corresponding to the $\Upsilon(4S)$ resonance. These parameters are determined by fitting the proper decay-time distribution of a sample of 415 signal events. We obtain $A = 0.04^{+0.15}_{-0.14}\pm 0.05$ and $S = 0.75^{+0.20}_{-0.23}\pm 0.04$, where the first uncertainties are statistical and the second are systematic.
We report on a search for a resonance X decaying to a pair of muons in e + e − → μ + μ − X events in the 0.212 – 9.000 GeV / c 2 mass range, using 178 fb − 1 of data collected by the Belle II ...experiment at the SuperKEKB collider at a center of mass energy of 10.58 GeV. The analysis probes two different models of X beyond the standard model: a Z ′ vector boson in the L μ − L τ model and a muonphilic scalar. We observe no evidence for a signal and set exclusion limits at the 90% confidence level on the products of cross section and branching fraction for these processes, ranging from 0.046 fb to 0.97 fb for the L μ − L τ model and from 0.055 fb to 1.3 fb for the muonphilic scalar model. For masses below 6 GeV / c 2 , the corresponding constraints on the couplings of these processes to the standard model range from 0.0008 to 0.039 for the L μ − L τ model and from 0.0018 to 0.040 for the muonphilic scalar model. These are the first constraints on the muonphilic scalar from a dedicated search. Published by the American Physical Society 2024
The Beyond Compliance project, which began in July 2011 with funding from the Standards and Trade Development Facility for 2 years, aims to enhance competency and confidence in the South East Asian ...sub‐region by applying a Systems Approach for pest risk management. The Systems Approach involves the use of integrated measures, at least two of which are independent, that cumulatively reduce the risk of introducing exotic pests through trade. Although useful in circumstances where single measures are inappropriate or unavailable, the Systems Approach is inherently more complicated than single‐measure approaches, which may inhibit its uptake. The project methodology is to take prototype decision‐support tools, such as Control Point‐Bayesian Networks (CP‐BN), developed in recent plant health initiatives in other regions, including the European PRATIQUE project, and to refine them within this sub‐regional context. Case studies of high‐priority potential agricultural trade will be conducted by National Plant Protection Organizations of participating South East Asian countries in trials of the tools, before further modifications. Longer term outcomes may include: more robust pest risk management in the region (for exports and imports); greater inclusion of stakeholders in development of pest risk management plans; increased confidence in trade negotiations; and new opportunities for trade.
We propose a new algorithm for the identification of the production flavor of neutral D mesons in the Belle II experiment. The algorithm exploits the correlation between the flavor of a reconstructed ...neutral D meson (signal D meson) and the electric charges of particles reconstructed in the rest of the e+e–→$c\bar{c}$ event. These include those originating from the decay of the other charm hadron produced in the event, as well as those possibly produced in association with the signal D meson. We develop the algorithm using simulation and calibrate it in data using decay modes that identify the flavor of the decaying neutral D meson. We use a data sample of e+e– collisions, corresponding to 362 fb–1 of integrated luminosity, collected by Belle II at center-of-mass energies near the Υ(4S) mass. The effective tagging efficiency in data is (47.91±0.07 (stat) ±0.51 (syst)) %, independent of the neutral-D-meson decay mode. This charm flavor tagger will approximately double the effective sample size of many CP-violation and charm-mixing measurements that so far have exclusively relied on neutral D mesons originating from D*± decays. While developed for Belle II, the basic principles underlying the charm flavor tagger can be used in other experiments, including those at hadron colliders.
Fe3O4 nanoparticles decorated on cellulose aerogel (CA) from banana stems (Fe3O4@CA) were synthesized for application in the Fenton degradation of p-nitrophenol (PNP). Cellulose aerogel extracted ...from raw banana stems was synthesized with kymene as a crosslinking agent and freeze-dried method. The Fe3O4@CA samples were characterized by X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS). The samples with different contents of Fe3O4 on cellulose aerogel were investigated for the degradation yield of PNP in water. The affect of the loaded content of Fe3O4 and H2O2 concentration on the PNP treatment efficiency were also investigated to suggest suitable values including the Fe3O4 catalyst content loaded on CA of 0.40 g/g and the H2O2 concentration of 5.0 g/L. As the results, Fe3O4@CA reached the removal efficiency of 87.92% in 100 mins to obey the pseudo-first kinetic model with a reaction rate constant of 0.0301 min−1. This study’s finding provides a method for creating environmentally friendly catalytic material, which might be used in green chemical engineering.
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•Material of Fe3O4 nanoparticles decorated on cellulose aerogel from the banana stem.•Properties and activity in p-Nitrophenol degradation of Fe3O4@CA were assessed.•Fe3O4 content and the suitable condition of the degradation have been carried out.•Fe3O4@CA enhanced Fenton degradation of p-Nitrophenol.
A search for the flavor-changing neutral-current decay B+→ K+νν is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to ...an integrated luminosity of 63 fb−1 collected at the Υ(4S) resonance and a sample of 9 fb−1 collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B+ → K+νν decay, but also the inclusive properties of the other B meson in the Υ(4S) → BB event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B+ → K+νν of 4.1 × 10−5 is set at the 90% confidence level.
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