Limits on neutrino-antineutrino transitions from a study of high-energy neutrino interactions

We distinguish electron and positron tracks from ν_e and $\text{ν}{}_{\mathrm{<mtext>e</mtext>}}$ charged-current interactions in a large bubble chamber f ed with a neon-hydrogen mixture. No evidence is seen for an excess of $\text{ν}{}_{\mathrm{<mtext>e</mtext>}}$ interactions from primary $\text{ν}{}_{\mathrm{<mtext>e</mtext>}}$ sources secondary $\text{ν}{}_{\mathrm{\mu }}\text{→}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{or}$$\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{→}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}$ oscillations. Upper limits on oscillation parameters, majoron sion and lepton-number violating π and K decays are presented.     

Experimental limits on the mass and decay lifetime of νμ

The nonobservation of photon-induced e⁺e^? pairs pointing in the neutrino beam direction in large bubble chambers would allow one to set an upper limit on the product m_νμλ^CM for muon-type neutrinos, where m_νμ is the mass and λ^CM is the intrinsic partial decay width in sec^?1 for ν_μ→γ+X. In the theory of Eliezer and Ross where , this implies an upper limit on m_νμ considerably smaller than the present upper limit, and a large lower limit on the lifetime τ_νμ.     

Leptonic nonet in SUL (3) × SUR (3)

A left-right symmetric SU_L(3) × SU_R(3) gauge model with leptons in the ($\text{3}\text{, 3) + (3,}\text{3}$) representation is presented. The SU^I_L(2)×U(1) subgroup is practically the WS + GIM model for $\text{sin}{}^2\text{?}{}_{\mathrm{<mtext>W</mtext>}}\text{≈}\text{3}\text{8}$, with additional currents involving heavy leptons. μ→eγ is naturally suppressed and a new kind of $\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{?}\text{ν}{}_{\mathrm{\mu }}$ oscillations is possible. τ and 3_μ events can be related to one leptonic triplet. The model is naturally imbedded in exceptional groups.     

Beam dump eμ asymmetry of charged Higgs origin

We raise the possibility that the reported breakdown of $\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{ν}{}_{\mathrm{\mu }}$ universality in prompt neutrino events observed in beam dumps experiments is due to non-universality in charm decays. The exchange of a virtual charged Higgs boson in charm decays could account for the asymmetry.     

Possible heavy lepton signals at pp colliders

If a new sequential heavy lepton L exists with mass below that of the W boson, it will give rise to the following decay chains: W → Lν_Lwith $\text{L}\text{→}\text{e}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{ν}{}_{\mathrm{<mtext>L</mtext>}}$ or $\text{L}\text{→}\text{Q}\text{qν}{}_{\mathrm{<mtext>L</mtext>}}$. We critically study, and quantify, the possibility of identifying this heavy lepton signal against the various backgrounds in high energy p?p collision. We find that the leptonic decay signal is plagued by serious b?b, W → eν, and W → τν backgrounds, whereas the hadronic decay mode leads to a distinctive signature, after selected cuts are applied. We discuss how the mass of such a lepton may be determined.     

Neutral currents and stellar cooling

If weak neutral currents couple with the strengths suggested by recent experiments, then stellar cooling via neutrino pair emission from thermally excited nuclear states may be significant in white dwarfs with central temperature ?10^8° K. At higher temperatures, other neutrino cooling processes are more important. In the sun, the decay of thermally excited ⁵⁷Fe nuclei may produce a moderately large, but probably unobservable, low-energy flux of ν_μ, $\text{g}\text{?}\text{n}{}_{\mathrm{\mu }}$, ν_e, and $\text{g}\text{?}\text{n}{}_{\mathrm{e}}$ neutrinos.     

The intermediate weak boson and weak interactions at high energy

The high-energy pire-leptonic weak interaction is investigated based on the assumption of the existence of a charged vector boson which mediates the weak processes. With the aid of the fixed-t dispersion relation the following relation is obtained: The weak boson mass m_W should satisfy $\text{m}{}_{\mathrm{<mtext>W</mtext>}}\text{? G}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$, with G the Fermi coupling constant, if the asymptotic value of the cross section becomes of the order of the strong interaction in the energy region observable in cosmic rays, etc.The scattering processes $\text{e}\text{+ν→}\text{e}\text{+ν}\text{and}\text{e}\text{+}\text{ν}\text{→}\text{e}\text{+}\text{ν}$ are examined by the aid of the N/D method. For a large vector-boson mass $\text{m}{}_{\mathrm{<mtext>W</mtext>}}\text{?100}\text{GeV}$, an S-wave resonance should exist for the process e+ν→e+ν while for $\text{e}\text{+}\text{ν}\text{→}\text{e}\text{+}\text{ν}$ there should exist a P-wave resonance which corresponds to the intermediate weak boson. The neutral current is then estimated. It is shown that the neutral current produced as a higher-order effect is not inconsistent with the present experiments on the pure-leptonic weak interaction if m_W?1 TeV.     

A search at high energies for antineutrino-electron elastic scattering

We have searched for candidates for the weak neutral leptonic current reaction $\text{ν}{}_{\mathrm{\mu }}\text{+}\text{e}{}^{\mathrm{?}}\text{→}\text{ν}{}_{\mathrm{\mu }}\text{+}\text{e}{}^{\mathrm{?}}$ in the Fermilab 15 ft bubble chamber filled with a heavy neon-hydrogen mix. Based on zero observed events of this type we find the 90% confidence level upper limit for the rate for this reaction relative to the total antineutrino charged current rate to be 3.9 × 10^?4 and, in the Weinberg-Salam model, sin²θ_W ? 0.37.     

An upper limit to the cross section for the reaction νμe−→νμe− at SPS energies

Candidates for the purely leptonic process $\text{ν}{}_{\mathrm{\mu }}\text{e}{}^{\mathrm{?}}\text{→}\text{ν}{}_{\mathrm{\mu }}\text{e}{}^{\mathrm{?}}$ have been searched for in the bubble chamber Gargamelle exposed to the CERN-SPS antineutrino wide-band beam. No single e^?, of energy greater than 1 GeV, was found in a total of 230 000 pictures, corresponding to 7400 charged current events. This leads to an upper limit for the observed cross section of $\text{σ}{}_{\mathrm{<mtext>obs</mtext>}}\text{< 1.6 × 10}{}^{\mathrm{?42}}\text{(}\text{E}{}_{\mathrm{\nu }}{}^{\mathrm{?}}\text{GeV}\text{)}$ cm² (90% C.L.). Interpretation of this value in terms of the standard W Weinberg-Salam model yields an upper limit to the mixing parameter sin²θ_W < 0.39 at 90% C.L.     

Corrections to νe−νμ universality in neutral current interactions

We examine the effects of higher-order corrections on the universality between ν_μ and ν_e in the Weinberg-Salam model. The leading correction to neutral current amplitudes is an apparent difference in the values of sin²θ as measured by ν_μ and ν_e beams. The difference is .     

Constraints on the reaction νμ(νμ) + Z → νμ(νμ) + μ− + μ+ + Z in theories with neutral currents

In the presence of neutral lepton currents, the characteristics of the reaction $\text{ν}{}_{\mathrm{\mu }}\text{(}\text{ν}{}_{\mathrm{\mu }}\text{) +}\text{Z}\text{→ ν}{}_{\mathrm{\mu }}\text{(}\text{ν}{}_{\mathrm{\mu }}\text{) + μ}{}^{\mathrm{?}}\text{+ μ}{}^{\mathrm{+}}\text{+}\text{Z}$ are modified from those expected in the conventional V-A theory. We show that in a very general class of intermediate boson theories, the modification produced can be specified entirely in terms of the cross sections for $\text{ν}{}_{\mathrm{\mu }}\text{(}\text{ν}{}_{\mathrm{\mu }}\text{) +}\text{e}{}^{\mathrm{?}}\text{→ ν}{}_{\mathrm{\mu }}\text{(}\text{ν}{}_{\mathrm{\mu }}\text{) +}\text{e}{}^{\mathrm{?}}$. Such a constraint does not necessarily exist in models with four-fermion interaction.     

Poincaré gauge invariance and the dynamical role of spin in gravitational theory

We classify, according to the number of independent gauge fields, Poincaré gauge invariant theoretical frameworks of describing gravity into three categories. One of them may provide the dynamical definition of the spin tensor S and that of the energy-momentum tensor T, resulting in the response equation of matter to gravity with the gravitational field strengths, D′ and F, coupled to the former tensors

$\text{T}{}_{\mathrm{\nu }}{}^{\mathrm{\mu }}\text{;}{}_{\mathrm{\mu }}\text{=D′}{}_{\mathrm{\mu \lambda \nu }}\text{T}{}^{\mathrm{\mu \lambda }}\text{+F}{}_{\mathrm{\mu \lambda \nu \rho }}\text{S}{}^{\mathrm{\rho \mu \lambda }}$

, where the right-hand side represents spin force densities. In the absence of spin the response reduces to the conventional one of general relativity, i.e., without the spin forces. For the electromagnetic field the phase-gauge invariance requires the same conclusion as for a scalar field. For a spin $\text{1}\text{2}$ particle there is torsion, which deflects its trajectory from geodesic; an explicit expression for torsion takes a simple form of the axial vector current $\text{ψ}\text{γ}{}_5\text{γ}{}_{\mathrm{k}}\text{ψ}$.     

Electromagnetic field in the gauge SU(3) × SU(3) chiral group

The massless electromagnetic Yang-Mills field is explicitly constructed as a linear combination of 16 gauge fields of the chiral SU(3) × SU(3) group within the framework of the plasmon generating mechanism [1]. The remaining 15 gauge fields acquire a mass through the non-zero vacuum expectation values of the auxiliary scalar multiplet which transforms according to the (8,8) representation of the gauge group. The tadpoles with non-zero hypercharge which are required for the existence of the only massless electromagnetic potential A_μ are due to the natural mixing of charged weak currents with ΔS = 0 and ΔS = 1. The relevance of this phenomenon to the Cabibbo angle is briefly discussed. Also presented is a theorem concerning an admissible form of the zero-order mass term of gauge fields when the canonical number is unknown.     

Radiative corrections to neutrino-lepton scattering in the SU(2)L ⊗ U(1) theory

The radiative corrections of O(α) to the final electron spectrum and the total cross sections for the processes $\text{ν}{}_{\mathrm{\mu }}\text{+}\text{e}\text{→ ν}{}_{\mathrm{\mu }}\text{+}\text{e}\text{,}\text{ν}{}_{\mathrm{\mu }}\text{+}\text{e}\text{→ ν}{}_{\mathrm{<mtext>e</mtext>}}\text{+}\text{e}\text{, ν}{}_{\mathrm{<mtext>e</mtext>}}\text{+}\text{e}\text{→ ν}\text{e}\text{+}\text{e and}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{+}\text{e}$ are studied in the framework of the SU(2)_L ? U(1) theory. The electroweak corrections to the fisrt two processes are presented in two equivalent schemes in terms of (G_μ, sin²θ_w) and $\text{(G}{}_{\mathrm{\mu }}\text{,}\text{sin}{}^2\text{θ}\text{?}{}_{\mathrm{<mtext>w</mtext>}}\text{(m}{}_{\mathrm{<mtext>w</mtext>}}\text{))}$. As a byproduct, the relationship to O(α) between the basic parameters $\text{sin}{}^2\text{θ}{}_{\mathrm{<mtext>W</mtext>}}\text{≡ 1 ? m}{}_{\mathrm{<mtext>W</mtext>}}{}^2\text{/m}{}_{\mathrm{<mtext>Z</mtext>}}{}^2\text{and sin}{}^2\text{θ}\text{?}{}_{\mathrm{<mtext>W</mtext>}}\text{(m}{}_{\mathrm{<mtext>W</mtext>}}\text{)}$ (defined by modified minimal subtraction) is explicitly given. The QED corrections are evaluated in the extreme relativistic (ER) regime of the final electron (E′_e ? m_e) for the situation in which the bremsstrahlung photons are unobserved and unrestricted. The ER approximation allows us to obtain simple analytic expressions for the differential electron spectrum and the total cross sections. The relationship to O(G_Fα) between the spin-averaged differential cross sections for the above processes in the ER regime is derived.     

Measurements of tau decay modes and a precise determination of the mass

The cross sections for e⁺e^? → e⁺(μ⁺ + non showering track + any photons have been measured for cm energies between 3.1 GeV and 5.2 GeV. We observe τ-pair production below the thresholdfor charm production and determine the τ mass to be 1.807 ± 0.020 GeV from a fit to the energy dependence of the cross section. The ration of the leptonic branching ratios B_μ/B_e = 0.92 ± 0.32 is consistent with eμ-universality. The following branching ratios are determined for a V-A coupling: $\text{B(τ → ν}{}_{\mathrm{\tau }}\text{e}\text{ν}\text{) = B(τ → ν}{}_{\mathrm{\tau }}\text{μ}\text{ν}\text{) = 0.182 + 0.028}$. B(τ → ν_τ + charged hadron + any photons) = 0.29 ± 0.11, B(τ → ν_τ + three or more charged hadrons + any photons) = 0.35 ± 0.11.     

The price of natural flavour conservation in neutral weak interactions

The natural conservation of flavours to O(G_F²) in neutral weak interactions severely constrains choices of gauge groups as well as their fermion representations. In the absence of exactly conserved quantum numbers other than charge, and of |ΔQ| ? 2 charged currents, essentially the only weak and electromagnetic gauge groups whose neutral interactions naturally conserve all flavours are SU(2)_L ? U(1) and SU(2)_L ? [U(1)]². The plausible extensions of these gauge groups to grand unified models including the strong interactions are based on SU(5) and SO(10) respectively. Making the SU(5) model completely natural, including in the Higgs sector, gives the prediction $\text{m}{}_{\mathrm{<mtext>d</mtext>}}\text{/m}{}_{\mathrm{<mtext>e</mtext>}}\text{? m}{}_{\mathrm{<mtext>s</mtext>}}\text{/m}{}_{\mathrm{\mu }}\text{? m}{}_{\mathrm{<mtext>b</mtext>}}\text{/m}{}_{\mathrm{\tau }}\text{? 2605}$ where τ is the probable new heavy lepton and b is the conjectured third flavour of charge $\text{?1}\text{3}\text{quark}$. The SO(10) model contains a potential SU(2)_L ? SU(2)_R ? U(1) weak and electromagnetic gauge group, and has a complicated Higgs structure which does not naturally conserve quark flavours.     

Time reversal violation in neutrino oscillation

We discuss the possibility of CP or T violation in neutrino oscillation. CP requires ν_μ ? ν_e and $\text{ν}\text{?}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}$ oscillations to be equal. Time reversal invariance requires the oscillation probability to be an even function of time. Both conditions can be violated, even drastically, if more than two neutrinos exist.     

Infrared spectrum of acetonitrile: Analysis of Coriolis resonance

The Coriolis resonance between ν₄ and ν₇ in CH₃CN and between ν₁ and ν₅, ν₃ and ν₆, and ν₄ and ν₇ in CD₃CN has been analyzed, applying the technique developed by DiLauro and Mills, to obtain the signs of [$\text{ζ}{}_{\mathrm{r,sa}}{}^{\mathrm{y}}\text{(}\text{?p}\text{?Q}{}_{\mathrm{r}}\text{)(}\text{?p}\text{?Q}{}_{\mathrm{sa}}\text{)}$] and the ratio of $\text{?μ}\text{?Q}{}_{\mathrm{r}}$ to $\text{?μ}\text{?Q}{}_{\mathrm{s}}$ for the interacting pairs in CD₃CN. For (ν₄, ν₇) in both CH₃CN and CD₃CN, the sign of [$\text{ζ}{}_{\mathrm{r,sa}}{}^{\mathrm{y}}\text{(}\text{?p}\text{?Q}{}_{\mathrm{r}}\text{)(}\text{?p}\text{?Q}{}_{\mathrm{sa}}\text{)}$] is found to be negative as it is also for (ν₁, ν₅) in CD₃CN. For (ν₃, ν₆) the sign of this interaction term is found to be positive. For a given definition of normal coordinates the signs of these interaction terms give the relative signs of $\text{?p}\text{?Q}{}_{\mathrm{r}}$ and $\text{?p}\text{?Q}{}_{\mathrm{sa}}$; our study also gives approximate values for the corresponding ratio [$\text{(}\text{?p}\text{?Q}{}_{\mathrm{r}}\text{)}\text{(}\text{?p}\text{?Q}{}_{\mathrm{sa}}\text{)}$]     

The ′T Hooft-Polyakov monopole near the Prasad-Sommerfield limit

A perturbative classical monopole solution for the SO(3) gauge theory is constructed in the limit of small but non-vanishing Higgs potential. This corresponds to the limit $\text{μ}{}^2\text{2M}{}_{\mathrm{W}}{}^2\text{=}\text{λ}\text{? 1}$, where μ equals the mass of the scalar particle and M_W equals the mass of the intermediate vector particles. The monopole solution and mass are found to involve non-analytic functions of λ: $\text{γ}$ and λ ln λ. The monopole mass M_m is calculated to order $\text{μ}{}^2\text{M}{}_{\mathrm{W}}$ as

$\text{M}{}_{\mathrm{m}}\text{=}\text{4π}\text{e}{}^2\text{M}{}_{\mathrm{w}}\text{1+}\text{1}\text{2}\text{μ}\text{M}{}_{\mathrm{w}}\text{+}\text{1}\text{2}\text{μ}{}^2\text{M}{}^2{}_{\mathrm{w}}\text{ln}\text{μ}\text{M}{}_{\mathrm{w}}\text{+0.7071}\text{μ}{}^2\text{M}{}^2{}_{\mathrm{w}}$

.     

Flavor changing neutral currents and multileptons in e+e- and vμN,vμN

New quarks and new flavor-changing neutral currents give multiple lepton plus hadron final states in e⁺e^-, $\text{v}{}_{\mathrm{\mu }}\text{N,}\text{v}{}_{\mathrm{\mu }}\text{N}$. We observe that (i) e⁺e^- is a favored place to search for their effects through inclusive ratios σ(e⁺e^-+x:σ (μ⁺μ^- +x): σ(e±μ±+x) and same sign leptons e±e±+x, μ±μ±+x,e±μ±+x. Above a new flavor threshold four charged lrpton final states may become important. (ii) Trilepton final states in $\text{v}{}_{\mathrm{\mu }}\text{N,}\text{v}{}_{\mathrm{\mu }}\text{N}$ are not sensitive to the presence of flavor-changing neutral currents. Much more sensitive are the processes $\text{v}{}_{\mathrm{\mu }}\text{N}$ are ⁺e^-+βand (for charm changing neutral currents) $\text{v}{}_{\mathrm{\mu }}\text{N→e}{}^{\mathrm{+}}\text{β}$.