Differentieller Wirkungsquerschnitt für die Photospaltung des Deuterons zwischen 20 und 35 MeV

The differential cross section of the deuteron photodisintegration was determined in the photon energy range 20 to 35 MeV at the angle of 90 degrees in the laboratory system. The experimental points were fitted in this range by a parabola $$d\sigma _D (90^\circ )/d\Omega = 140.6 - 5.41{\rm E}_\gamma + 0.0621E_\gamma ^2 $$ withE in MeV anddσ _D /dΩ in 10^?30 cm²/sr.     

Neutral strange particle exclusive production in charged current high-energy antineutrino interactions

The cross section of the quasi-elastic reactions \(\bar v_\mu p \to \mu ^ + \Lambda (\Sigma ^0 )\) in the energy range 5–100 GeV is determined from Fermilab 15′ bubble chamber antineutrino data. TheQ ² analysis of quasi-elastic Λ events yieldsM _A=1.0±0.3 GeV/c² for the axial mass value. With zero µΛ K ⁰ events observed, the 90% confidence level upper limit \(\sigma (\bar v_\mu p \to \mu ^ + \Lambda {\rm K}^0 )< 2.0 \cdot 10^{ - 40} cm^2 \) is obtained. At the same time, we found that the cross section of reaction \(\bar v_\mu p \to \mu ^ + \Lambda {\rm K}^0 + m\pi ^0 \) is equal to \(\left( {3.9\begin{array}{*{20}c} { + 1.6} \\ { - 1.3} \\ \end{array} } \right) \cdot 10^{ - 40} cm^2 \) .     

Exponential lower bounds to solutions of the Schrödinger equation: Lower bounds for the spherical average

For a large class of generalizedN-body-Schrödinger operators,H, we show that ifE<Σ=infσ_ess(H) and ψ is an eigenfunction ofH with eigenvalueE, then $$\begin{array}{*{20}c} {\lim } \\ {R \to \infty } \\ \end{array} R^{ - 1} \ln \left( {\int\limits_{S^{n - 1} } {|\psi (R\omega )|} ^2 d\omega } \right)^{1/2} = - \alpha _0 ,$$ with α ₀ ² +E a threshold. Similar results are given forE≧Σ.     

Some implications of inclusive electro- and neutrino production data

We systematically exploit the reported data on \(F_2^{\gamma p} ,F_2^{\gamma n} ,\sigma ^{vN} ,\sigma ^{\bar vN} ,\left\langle {xy} \right\rangle _{vN} ,\left\langle {xy} \right\rangle _{\bar vN} ,\left\langle {1 - y} \right\rangle _{vN} \) and \(\left\langle {1 - y} \right\rangle _{\bar vN} \) in order to test various versions of the quark parton model and to obtain further predictions.     

Universal estimate of the gap for the Kac operator in the convex case

The aim of this paper is to prove that ifV is a strictly convex potential with quadratic behavior at ∞, then the quotient μ₂/μ₁ between the largest eigenvalue and the second eigenvalue of the Kac operator defined on L²(? ^m ) by exp ?V(x)/2 · exp Δ_x · exp ?V(x)/2 where Δ_x is the Laplacian on ? ^m satisfies the condition: $${{\mu _2 } \mathord{\left/ {\vphantom {{\mu _2 } {\mu _1 {{ \leqslant \exp - \cosh ^{ - 1} (\sigma + 1)} \mathord{\left/ {\vphantom {{ \leqslant \exp - \cosh ^{ - 1} (\sigma + 1)} {2,}}} \right. \kern-\nulldelimiterspace} {2,}}}}} \right. \kern-\nulldelimiterspace} {\mu _1 {{ \leqslant \exp - \cosh ^{ - 1} (\sigma + 1)} \mathord{\left/ {\vphantom {{ \leqslant \exp - \cosh ^{ - 1} (\sigma + 1)} {2,}}} \right. \kern-\nulldelimiterspace} {2,}}}}$$ where σ is such that HessV(x)≥σ>0.     

Neutral pion photoproduction on tensor-polarized deuterium on the VEPP-3 storage ring

An experiment to measure component T ₂₀ of the tensor analyzing power for the coherent photo-production of neutral pions on polarized deuterons is described. The measurements cover the photon energies in the ranges E _γ = 200–500 MeV and E _γ = 300–600 MeV, and the emission angles of neutral pions in the ranges = \(\theta _{\pi ^0 }^{c.m.} \) = 100°–140° and = \(\theta _{\pi ^0 }^{c.m.} \) = 60°–65°, respectively. The experiment uses a hyperfine internal gas polarized target. Detectors of neutral pions and deuterons register these particles in coincidence. The target’s degree of polarization and luminosity is measured by detecting elastic electron-deuteron scattering at low momentum transfer. A selection of the preliminary results is presented.     

On the Lieb-Thirring constantsL γ,1 for γ≧1/2

LetE _i(H) denote the negative eigenvalues of the one-dimensional Schrödinger operatorHu??u″?Vu,V≧0, onL ₂(∝). We prove the inequality (1) $$\mathop \sum \limits_i |E_i (H)|^{ \gamma } \leqq L_{\gamma ,1} \mathop \smallint \limits_\mathbb{R} V^{\gamma + 1/2} (x)dx,$$ for the “limit” case γ=1/2. This will imply improved estimates for the best constantsL _γ,1 in (1) as 1/2<γ<3/2.     

Radiative Σ± decays and search for neutral currents

The decay modesΣ ^±→nπ ^± γ, Σ ⁺→pγ,Σ ⁺ →pe ⁺ e ^}- were studied in the 81 cm Saclay hydrogen bubble chamber. In the radiative decayΣ ^±→nπ ^± γ only low momentum pions which stop in the chamber were accepted. We obtain the following branching ratios: (1) $$\frac{{\Gamma {\text{(}}\sum ^{\text{ + }} \to n\pi ^ + \gamma , p_{\pi + }^*< 110{\text{ MeV/c)}}}}{{\Gamma {\text{(}}\sum ^{\text{ + }} \to n\pi ^ + )}} = (2.7 \pm 0.5) \times 10^{ - 4} ,$$ (2) $$\frac{{\Gamma {\text{(}}\sum ^ - \to n\pi ^ - \gamma , p_{\pi - }^*< 110{\text{ MeV/c)}}}}{{\Gamma {\text{(}}\sum ^ - \to n\pi ^ - )}} = (1.0 \pm 0.2) \times 10^{ - 4} ,$$ (3) $$\frac{{\Gamma {\text{(}}\sum ^ + \to p\gamma {\text{)}}}}{{\Gamma {\text{(}}\sum ^ + \to p\pi ^0 )}} = (2.1 \pm 0.3) \times 10^{ - 3} ,$$ (4) $$\frac{{\Gamma {\text{(}}\sum ^ + \to pe^ + e^ - {\text{)}}}}{{\Gamma {\text{(}}\sum ^ + \to p\pi ^0 )}} = (1.5 \pm 0.9) \times 10^{ - 5} .$$ The radiative branching ratios (1) and (2) agree well with theoretical calculations and confirm very strongly the assignmentS wave toΣ ^? →nπ ^? andP wave toΣ ⁺→nπ ⁺ decay. The branching ratio (4) is based on 3 events with very low invariant masses of the electron-positron pair, being most probably radiative decays with internal conversion of theγ-ray. Combining (3) and (4) we obtain for the conversion coefficientρ: in agreement with predictions from electrodynamics.     

Charged Higgs Boson Contribution to \overline{\nu}_{e}-e Scattering from Low to Ultrahigh Energy in Higgs Triplet Model

We study the $\overline{\nu}_{e}-e$ scattering from low to ultrahigh energy in the framework of Higgs Triplet Model (HTM). We add the contribution of charged Higgs boson exchange to the total cross section of the scattering. We obtain the upper bound $h_{ee}/M_{H^{\pm}}\lesssim2.8\times10^{-3}~\mbox{GeV}^{-1}$ in this process from low energy experiment. We show that by using the upper bound obtained, the charged Higgs contribution can give enhancements to the total cross section with respect to the SM prediction up to 5.16 % at E≤10¹⁴ eV and maximum at $s\approx M_{H^{\pm}}^{2}$ and would help to determine the feasibility experiments to discriminate between SM and HTM at current available facilities.     

Experimental determination of the branching ratiosp\bar p \to 2\pi ^0 ,\pi ^0 \gamma,and 2γ at rest

The branching ratios of \(p\bar p\) annihilations into the neutral final states 2π⁰, π⁰γ, and 2γ are measured by stopping antiprotons in liquid hydrogen. They are \(B_{2\pi ^0 } = \left( {2.06 \pm 0.14} \right) \times 10^{ - 4} \) , \(B_{\pi ^0 \gamma } = \left( {1.74 \pm 0.22} \right) \times 10^{ - 5} \) , andB _γγ<1.7×10^?6 (95% c.l.).     

Large Time Asymptotics for the Kadomtsev–Petviashvili Equation

We study the large time asymptotic behavior of solutions to the Kadomtsev–Petviashvili equations $$\left\{\begin{array}{ll} u_{t} + u_{xxx} + \sigma \partial_{x}^{-1}u_{yy} = -\partial_{x}u^{2}, \quad \quad (x, y) \in {\bf R}^{2}, t \in {\bf R},\\ u(0, x, y) = u_{0}( x, y), \, \quad \quad \qquad \qquad (x, y) \in {\bf R}^{2},\end{array}\right.$$ where σ = ±1 and \({\partial_{x}^{-1} = \int_{-\infty}^{x}dx^{\prime} }\) . We prove that the large time asymptotics of the derivative u _x of the solution has a quasilinear character.     

Measurement of the inclusive charged-current cross section for neutrino and antineutrino scattering on isoscalar nucleons

This paper reports on measurements of the total cross section for the inclusive reaction v_μ+N , as a function of incident energy. Neutrinos and antineutrinos with energy in the range 30–300 GeV were produced in the 1982 Fermilab narrow-band neutrino beamline. A total of 35 000 neutrino and 7000 antineutrino interactions were recorded in the CCFR detector located in LabE. The incident neutrino flux was determined by methods similar to those used in previous experiments. The rate of increase with energy of the total cross section (σ/E _v) in the range 30 to 75 GeV was determined to be 0.659±0.005(stat)±0.039(syst)×10^?38 cm²/GeV and 0.307±0.008(stat)±0.020(syst)×10^?38 cm²/GeV for incident neutrinos and antineutrinos, respectively. The 5.9% systematic errors are due primarily to uncertainties in the flux intensity measurement. The energy dependence of the cross section in the regionE _ν=100–300 GeV was found to be linear, as determined by relative normalization techniques. A weighted average of our previous and present measurement for the total ν-N cross section yields: $$\begin{gathered} \sigma (vN) = 0.666 \pm 0.020(statistical \hfill \\ + systematic)E_v 10^{ - 38} cm^2 ; \hfill \\ \sigma (\bar vN) = 0.324 \pm 0.014(statistical \hfill \\ + systematic)E_v 10^{ - 38} cm^2 ; \hfill \\ \end{gathered} $$ .     

Test of 600 and 750 MeV NN matrix on elastic scattering Glauber model calculations

The 600 and 750 MeV proton nucleus elastic scattering cross section and polarization calculations have been performed in the framework of the Glauber model to test the pp and pn scattering amplitudes deduced from a phase shift analysis by Bystricky, Lechanoine and Lehar. It is well known that up to now we do not possess a non-phenomenological NN scattering matrix at intermediate energies. However proton-nucleus scattering analyses are used to extract information about short range correlations¹), Δ resonance²) or pion condensation presences)... etc. Most scattering calculations made at these energies have been done with phenomenological NN amplitudes having a gaussian q-dependence $$A(q) = \frac{{k\sigma }}{{4\pi }}(\alpha + i) e^{ - \beta ^2 q^2 /2} $$ and $$C(q) = \frac{{k\sigma }}{{4\pi }}iq(\alpha + i) D_e - \beta ^2 q^2 /2$$ K andσ being respectively the projectile momentum and the total pN total cross section. The parameters α, β and D are badly known and are adjusted by fitting some specific reactions as p+⁴He elastic scattering⁴). Even when these amplitudes provide good fits to the data, our understanding of the dynamics of the scattering remains obscure.     

Conserved-vector-current hypothesis and the\bar v_e e^ - \to \pi ^ - \pi ^0 process

Based on the conserved-vector-current (CVC) hypothesis and a four-ρ-resonance unitary and analytic VMD model of the pion electromagnetic form factor, theσ _tot(E _v ^lab ) and dσdE _π ^lab of the weak \(\bar v_e e^ - \to \pi ^ - \pi ^0\) process are predicted theoretically for the first time. Their experimental approval could verify the CVC hypothesis for all energies above the two-pion threshold. Since, unlike the electromagnetic e⁺e^?→π⁺π^? process, there is no isoscalar vector-meson contribution to the weak \(\bar v_e e^ - \to \pi ^ - \pi ^0\) reaction, accurate measurements of theσ _tot(E _v ^lab ) that moreover is strengthened with energyE _v ^lab linearly could solve now a widely discussed problem of the mass specification of the first excited state of theρ(770) meson. As a by-product, an equality \(\sigma _{tot} (\bar v_e e^ - \to \pi ^ - \pi ^0 ) = \sigma _{tot} (e^ + e^ - \to \pi ^ - \pi ^0 )\) is predicted for \(\sqrt s \approx 70 GeV\) .     

Nuclear matrix elements in the 7/2−–9/2+ beta decay of175Yb

The angular correlation of the \({7 \mathord{\left/ {\vphantom {7 2}} \right. \kern-0em} 2}^ - \xrightarrow[{353keV}]{\beta }{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-0em} 2}^ + \xrightarrow[{114keV}]{\gamma }{7 \mathord{\left/ {\vphantom {7 2}} \right. \kern-0em} 2}^ + \) is measured atE _β =300 keV and found to beA ₂(β,γ)=0.108 ± 0.028. The result is combined with the data on longitudinal polarisation nuclear orientation to obtain the nuclear matrix elements which would give a simultaneous fit to all experimental data. The matrix elements thus obtained have predicted theβ spectrum shape correction factor. The sizes of the matrix elements indicate a cancellation effect in vector matrix elements which explains deviation from ξ-approximation. From the ratio of higher order matrix elements,λ, the deviation from theCVC ratio due to Fujita is found and thus the importance of off-diagonal elements inH _c is noted. The experimental matrix elements are compared with the model-predicted ones.     

Observation of the Higgs Boson of strong interaction via Compton scattering by the nucleon

It is shown that the Quark-Level Linear σ Model (QLLσM) leads to a prediction for the diamagnetic term of the polarizabilities of the nucleon which is in excellent agreement with experimental data. The bare mass of the σ meson is predicted to be m _σ =666 MeV and the two-photon width Γ(σ→γ γ)=(2.6±0.3) keV. It is argued that the mass predicted by the QLLσM corresponds to the $\gamma\gamma\to\sigma\to N\bar{N}$ reaction, i.e. to a t-channel pole of the γ N→N γ reaction. Large-angle Compton scattering experiments revealing effects of the σ meson in the differential cross section are discussed. Arguments are presented that these findings may be understood as an observation of the Higgs boson of the strong interaction while being a part of the constituent quark.     

Search for rare radiative decays ofΦ-meson at VEPP-2M

Results of the search for rare radiative decay modes of the ?-meson performed with the Neutral Detector at the VEPP-2M collider are presented. For the first time upper limits for the branching ratios of the following decay modes have been placed at 90% confidence level: $$\begin{gathered} B(\phi \to \eta '\gamma )< 4 \cdot 10^{ - 4} , \hfill \\ B(\phi \to \pi ^0 \pi ^0 \gamma )< 10^{ - 3} , \hfill \\ B(\phi \to f_0 (975)\gamma )< 2 \cdot 10^{ - 3} , \hfill \\ B(\phi \to H\gamma )< 3 \cdot 10^{ - 4} , \hfill \\ \end{gathered} $$ whereH is a scalar (Higgs) boson with a mass 600 MeV<m _H <1000 MeV, the real measurement isB(φ→H γ)·B(H→2π⁰)<0.8·10^-4, the quoted result is model dependent, as explained in the text, $$\begin{gathered} B(\phi \to a\gamma ) \cdot B(a \to e^ + e^ - )< 5 \cdot 10^{ - 5} , \hfill \\ B(\phi \to a\gamma ) \cdot B(a \to \gamma \gamma )< 2 \cdot 10^{ - 3} , \hfill \\ \end{gathered} $$ wherea is a particle with a low mass and a short lifetime, $$B(\phi \to a\gamma )< 0.7 \cdot 10^{ - 5} ,$$ wherea is a particle with a low mass not observed in the detector.