Trilepton production by neutrinos and antineutrinos

We calculate the electromagnetic and hadronic contributions to neutrino production of μ^?e⁺e^? events and antineutrino production of μ⁺e⁺e^? events. Due to an increase in cross section and acceptance, these rates are much larger in bubble-chamber experiments than the corresponding rates for trimuon events in counter experiments. Verification of these rates would confirm our understanding of the physics behind trilepton events. We stress the importance of measuring also a rate for μ^?e^? events to determine the cross section for the associated production of charmed particles.     

Identifying neutrinos and antineutrinos in neutral-current scattering reactions

We study neutrino-induced nucleon knockout from nuclei. Expressions for the induced polarization are derived within the framework of the independent-nucleon model and the nonrelativistic plane-wave approximation. Large dissimilarities in the nucleon polarization asymmetries are observed between neutrino- and antineutrino-induced processes. These asymmetries represent a potential way to distinguish between neutrinos and antineutrinos in neutral-current neutrino scattering on nuclei. We discuss astrophysical applications of these polarization asymmetries. Our findings are illustrated for neutrino scattering on 16O and 208P b.     

Inclusive interactions of high-energy neutrinos and antineutrinos in iron

We present results on charged current inclusive neutrino and antineutrino scattering in the neutrino energy range 30–200 GeV. The results include a) total cross-sections; b)y distributions; c) structure functions; and d) scaling violations observed in the structure functions. The results, as well as their comparison with the results of electron and muon inclusive scattering, are in agreement with the expectations of the quark parton model and QCD.     

Determination of charm production cross-sections for neutrinos and antineutrinos

It is shown that existing data for production rates of opposite-sign dileptons by neutrinos and antineutrinos are mutually consistent when acceptance corrections are calculated using a standard four-quark parton model, and a flat fragmentation function for charmed quarks. Together with a corrected cross-section, model calculations which adequately describe the data are presented.     

Dilepton and trilepton production by antineutrinos and neutrinos in neon

A sample of over 25,000 fully measured neutrino and antineutrino charged current interactions in BEBC includes 192 dilepton candidates. The prompt signal after subtraction of background is 41 ±7µ⁺ e ^-, 35±7µ⁺µ^- events from \(\bar v\) interactions, and 32±7µ^-µ⁺ events from ν interactions. There are 2 trileptons, µ^-µ^- e ⁺ and µ^-µ^-µ⁺. Results are compared with other experimental data and with the standard model. Limits to prompt like sign µ⁺ e ⁺, µ⁺µ⁺ and µ^-µ^- signals are given and compared with other experiments and with theoretical calculations.     

Diffractive production of charmed strange mesons by neutrinos and antineutrinos

The diffractive production of charmed strangeD _s ^* and possiblyD _s mesons by neutrinos and antineutrinos on nucleons in hydrogen, deuterium and neon targets is observed. The slope parameter of thet distribution is 3.3±0.8 (GeV)^?2. The production rate per charged current neutrino interaction with an isoscalar target times the D _s ⁺ →φτ⁺ branching fraction is (1.03±0.27)×10^?4.     

Study of inclusive neutral current interactions of neutrinos and antineutrinos

We report on results from a study of hadron-energy distributions for ν and $\text{ν}$ inclusive neutral current interactions. There is no significant variation of the neutral to charged current total cross-section ratios R_ν and $\text{R}\text{ν}$ with neutrino energy. The space-time structure of neutral currents is dominated by V?A, with a significant admixture of V+A. The Weinberg-Salam model is in agreement with all data if sin²θ_w=0.24±0.02.     

Search for differences in oscillation parameters for atmospheric neutrinos and antineutrinos at Super-Kamiokande

We present a search for differences in the oscillations of antineutrinos and neutrinos in the Super-Kamiokande-I, -II, and -III atmospheric neutrino sample. Under a two-flavor disappearance model with separate mixing parameters between neutrinos and antineutrinos, we find no evidence for a difference in oscillation parameters. Best-fit antineutrino mixing is found to be at (Δm2,sin2 2θ)=(2.0×10(-3) eV2, 1.0) and is consistent with the overall Super-K measurement.     

Quasielastic nucleon and hyperon production by neutrinos and antineutrinos with energies below 30 GeV

The cross sections of neutrino and antineutrino quasielastic reactions \(vn \to \mu ^ - p,\bar vp \to \mu ^ + n,\bar vp \to \mu ^ + \Lambda\) were studied in the neutrino energy range between 3 and 30 GeV. In comparison withV-A theory axial mass parameters ofM _A =(1.06±0.05±0.14) GeV/c² from neutrino andM _A =(0.71±0.10±0.20) GeV/c² from antineutrino data were found. The total cross-section for the hyperon production process can be described byM _A =1.0 GeV/c².     

Neutral currents and elastic scattering of neutrinos and antineutrinos on a polarized proton target

The processes of elastic scattering of neutrinos and antineutrinos on a polarized proton target are considered on the basis of the Weinberg-Salam gauge theory. Expressions are found for the differential cross sections, spin asymmetry, and the degree of polarization of recoil protons in the reactions indicated. The formulas obtained are analyzed from the position of the latest experimental data on the Weinberg parameter.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 85–89, December, 1976.In conclusion it gives me pleasure to thank Prof. A. A. Sokolov and N. A. Guliev for their useful discussion and their interest in this paper.     

Deep inelastic scattering of neutrinos and antineutrinos by a polarized proton in the quark-parton model

Deep inelastic scattering of neutrinos and antineutrinos by polarized protons is considered in the quark-parton model. For processes with charged currents, a connection is obtained between the asymmetry of the differential cross sections corresponding to different spin directions of the target proton and the distribution functions of the polarized partons in the polarized proton (d for neutrinos and u for antineutrinos). It is shown that the presence of an x dependence of the asymmetry parameter corresponds to a difference between the distribution functions of partons with opposite helicity. For processes with neutral currents, relations are obtained between the asymmetry parameters and the constants that determine the helicity structure of the weak neutral quark current.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 41–45, April, 1980.I thank Professor B. K. Kerimov and A. É. Astratyan for a helpful discussion of the work.     

Excitation of the 15.110 MeV state of 12C by neutrinos or antineutrinos

Formulae for cross sections of $\text{ν}{}^{12}\text{C(g.s.)}\text{→ ν}{}^{12}\text{C}{}^1\text{(15.110)}$ and $\text{ν}{}^{12}\text{C(g.s.)}\text{→}\text{ν}{}^{12}\text{C}{}^1\text{(15.110)}$ and for angular distributions and circular polarizations of the subsequent decay photons are derived in a model-independent (elementary-particle) approach. Our results indicate that, granting validity of the isotriplet hypothesis which relates the isovector components of the hadronic neutral weak current to the hadronic charged weak polar and axial currents, the numerical predictions of these quantities are strikingly different between solutions A and B.     

Experimental study of structure functions and sum rules in charge-changing interactions of neutrinos and antineutrinos on nucleons

High-energy exclusive and inclusive cross sections are discussed in terms of their dependence on the transverse-position variables (impact parameters) of incident and outgoing particles. The objective is to clarify the points of conflict and agreement of various models with each other and with intuitive ideas based on macroscopic collisions. First the impact parameter representation of states and amplitudes is reviewed. New impact parameter conservation laws and sum rules are derived from Lorentz invariance. The generalized optical theorem of Mueller is extended to give the impact parameter distribution of produced particles. Mueller-Regge behaviour is shown to imply three-dimensional limiting fragmentation in (impact parameter, rapidity)- space and a specific linear structure of the final-state particle density in the central region of this space. The predictions of weak- and strong-coupling multiperipheral models, the φ³ ladder eikonal model and the dual resonance model are presented, with emphasis on the dependence of average multiplicity on impact parameter and the dependence of mean square impact parameter on multiplicity. Special techniques for strong-coupling multiperipheral models are used to study the breakdown of the random-walk impact-parameter structure of the weak-coupling case, and to show explicitly that the average multiplicity is a decreasing function of impact parameter in the strongly coupled ABFST model.     

Instantons on Gravitons

Yang-Mills instantons on ALE gravitational instantons were constructed by Kronheimer and Nakajima in terms of matrices satisfying algebraic equations. These were conveniently organized into a quiver. We construct generic Yang-Mills instantons on ALF gravitational instantons. Our data are formulated in terms of matrix-valued functions of a single variable, that are in turn organized into a bow. We introduce the general notion of a bow, its representation, its associated data and moduli space of solutions. For a judiciously chosen bow the Nahm transform maps any bow solution to an instanton on an ALF space. We demonstrate that this map respects all complex structures on the moduli spaces, so it is likely to be an isometry, and use this fact to study the asymptotics of the moduli spaces of instantons on ALF spaces.     

Billiards and Toy Gravitons

Journal of Statistical Physics - In this article we study the one-dimensional dynamics of elastic collisions of particles with positive and negative mass. We show that such systems are equivalent...     

有关“引力子”的话题

物理学家们认为四种基本力都是由粒子传递的:电磁力由光子传递,弱核力的传媒是W和Z玻色子,强核力是由胶子传递的,而引力则是由引力子(graviton)传递的.