807 research outputs found
Nutev anomaly & strange-antistrange asymmetry
No full textThe NuTeV Collaboration reported a value of sin(2)theta(w) measured in neutrino-nucleon deep inelastic scattering, and found that the value is three standard deviations from the world average value of other electroweak measurements. If this result cannot be explained within conventional physics, it must imply some novel physics beyond the standard model. We report the correction from the asymmetric strange-antistrange sea by using both the light-cone meson-baryon model and the chiral quark model, and show that a significant part of the NuTeV anomaly can be explained by the strange-antistrange asymmetry.Physics, Particles & FieldsCPCI-S(ISTP)
Age significance interpreted from Ar-40-Ar-39 dating of quartz samples from the Dongchuan Copper Deposits, Yunnan, SW China, by crushing and heating
No full textUnified parametrization of quark and lepton mixing matrices
No full textWe present a unified parametrization of quark and lepton mixing matrices. By using some simple relations between the mixing angles of quarks and leptons, i.e., the quark-lepton complementarity, we parametrize the lepton mixing matrix with the Wolfenstein parameters lambda and A of the quark mixing matrix. It is shown that the Wolfenstein parameter lambda can measure both the deviation of the quark mixing matrix from the unit matrix, and the deviation of the lepton mixing matrix from the exactly bimaximal mixing pattern.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)0ARTICLE9null7
Photon localization and lasing in disordered GaNxAs1-x optical superlattices
No full textWe propose an approach to fabricate a disordered optical superlattice using microcracking faces in GaNxAs1-x epilayers. Laser action is observed and the emission exhibits random laser behaviors. A transfer-matrix simulation suggests photon localization occurs at the lasing modes
Current oscillations and stable electric field domains in doped GaAs/AlAs superlattices
No full textThe crossover between two regimes has been observed in the vertical electric transport of weakly coupled GaAs/AlAs superlattices (SLs). At fixed d.c. bias, the SLs can be triggered by illumination to switch from a regime of temporal current oscillation to the formation of a stable electric field domain. The conversion can be reversed by raising the sample temperature to about 200 K. An effective carrier injection model is proposed to explain the conversion processes, taking into account the contact resistance originating from DX centres in the n(+)-Al0.5Ga0.5As contact layers which is sensitive to light illumination and temperature. In addition, quasiperiodic oscillations have been observed at a particular d.c. bias voltage
NuTeV anomaly versus strange-antistrange asymmetry
No full textWe report the correction from the asymmetric strange- antistrange sea of the nucleon by using both the light-cone baryon-meson fluctuation model and the chiral quark model, and show that a significant part of the NuTeV anomaly can be explained by the strange-antistrange asymmetry. We also show that the calculated s/(s) over bar asymmetry are compatible with the NuTeV data by including some additional symmetric s/(s) over bar quark contribution.Physics, NuclearPhysics, Particles & FieldsSCI(E)CPCI-S(ISTP)
An investigation of the formation mechanisms of electric field domains in GaAs/AlAs superlattices
No full textWe have studied the vertical transport and formation mechanisms of electric field domains in doped weakly-coupled GaAs/AlAs superlattices. Under hydrostatic pressure two kinds of sequential resonant tunneling are observed within the pressure range from 0 to 4.5 kbar. A transition from Gamma-Gamma to Gamma-X sequential resonant tunneling occurs at P-t approximate to 1.6 kbar. For P P-t it is preferentially formed by the Gamma-X process
Parity of antidecuplet baryons reexamined from chiral soliton models
No full textWe recalculate masses and widths of antidecuplet baryons in the case of positive parity from chiral soliton models, provided that the member Xi(3/2) of the antidecuplet has a mass 1.86 GeV, as reported recently. Calculations show that there are no convincing candidates for the nonexotic members of the antidecuplet available in the baryon listings. Up to the leading order of m(s) and 1/N-c, the width formula for the decay of the antidecuplet baryons to the octet depends only on SU(3) symmetry model independently, except the coupling constant. Similarly, we give a width formula for the decay of negative parity baryons belonging to certain SU(3) baryon multiplets by pure symmetry consideration. By this formula, we find that if we have an antidecuplet with negative parity and that the masses are the same as those given by chiral soltion models, the identification of N(1650) as N-(10) over bar are inconsistent with experiments for N(1650)-->Npi while the widths agree with other two decay channels involving strangeness. And Sigma(1750) seems to be a reasonable candidate for Sigma((10) over bar).Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)5ARTICLE9null7
Detection of cosmic neutrino clustering by cosmic ray spectra
No full textWe propose a method to investigate the scenario that cosmic relic neutrinos are highly clustered around stars and galaxies, or dark-matter clusters, rather than uniformly distributed in the universe. Such a scenario can be detected or constrained by the interaction of high-energy cosmic ray protons and nuclei with the cosmic neutrinos. There should be an observable signature in the energy spectra of cosmic ray protons and nuclei for a neutrino clustering factor beyond 10(13). We provide a relation on the signature onset positions between proton and nuclei spectra, and discuss possible support from existing experiments. It is also suggested that the relative abundance of cosmic ray nuclei may detect or constrain the cosmic neutrinos with smaller clustering.Physics, MultidisciplinarySCI(E)EI5ARTICLEnull
Heterologous inactivated virus/mRNA vaccination response to BF.7, BQ.1.1, and XBB.1
No full textThe emergence of highly immune-escape Omicron variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), such as BQ and XBB, has led to concerns about the efficacy of vaccines. Using lentivirus-based pseudovirus neutralizing assay, we showed that heterologous vaccination involving parental mRNA vaccine as a booster or second booster in individuals that received two or three doses of inactivated vaccines strongly augments the neutralizing activity against emerging Omicron subvariants, including BF.7, BQ.1.1, and XBB.1, by 4.3-to 219-folds. Therefore, a heterologous boosting strategy with mRNA-based vaccines should be considered in populations where inactivated vaccines were primarily used
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