Neutral heavy lepton candidate in e+e− interactions

An event of the form e⁺e^? → μ⁺μ^? + (2 jets) recently observed at √s = 43.45 GeV is interpreted as production of a pair of neutral heavy leptons N, each with mass 20.5 ± 1.0 Gev/c². Two possibilities are explored: (i) the lepton is a wak isodoublet neutrino, produced in pairs by virtual Z⁰ decay. In this case, one expects $\text{B(}\text{Z}{}^0\text{→}\text{N}\text{N}\text{) ≈ 5\%}$; (ii) the lepton is a “right-handed neutrino”, produced in pairs via a new vector boson Z_χ. In this case, in one model, the Z_χ must lie between about 50 and 67 GeV/c². More generally, it must be very weakly coupled to ordinary quarks and leptons in order not to conflict with low-q² neutral-current data. Suggestions are made for further observation of N$\text{N}$ pairs and other effects of Z_χ in forthcoming e⁺e^? and p$\text{p}$ collisions.     

Observation of planar three-jet events in e+e− annihilation and evidence for gluon bremsstrahlung

Topological distributions of charged and neutral hadrons from the reaction e⁺e^? → multihadrons are studied at √s of about 30 GeV. An excess of planar events is observed at a rate which cannot be explained by statistical fluctuations in the standard two-jet process. The planar events, mostly consisting of a slim jet on one side and a broader jet on the other, are shown actually to possess three-jet structure by demonstrating that the broader jet itself consists of two collinear jets in its own rest system. Detailed agreement between data and predictions is obtained if the process $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→q}\text{q}\text{?}\text{g}$ is taken into account. This strongly suggests gluon bremsstrahlung as the origin of the planar three-jet events. By comparison of the data with the qq?g-model we obtain a value for the strong coupling constant of α_S(q² = 0.17 ± 0.04.     

Radiative production of gravitinos and photinos in e+e− annihilation

We evaluate cross sections for the two processes e⁺e^? → γ-photino-antiphotino, e⁺e^? → γ-gravitino-antiphotino. In the local limit approximation they are proportional to $\text{α}{}^3\text{s}\text{m}{}^4$ (spin-0 electron) and $\text{G}{}_{\mathrm{Newton}}\text{α}{}^2\text{s}\text{m}{}^2$ (gravitino), respectively. I If spin-0 electrons have masses between 16 and $\text{40}\text{GeV}\text{c}{}^2$, the γ-photino-antiphotino production cross section would be of the order of 0.4 to 0.1 pb at $\text{s}\text{= 40}\text{GeV}$, with the cuts indicated in the text. Detecting this process is within the range of possibilities at PETRA. If no such signal is found the existence of light photinos coupled to spin-0 electrons lighter than $\text{≈40}\text{GeV}\text{c}{}^2$, or to gravitinos lighter than $\text{≈10}{}^{\mathrm{?6}}\text{eV}\text{c}{}^2$, would be excluded.     

Inclusive hadron production by e+e− annihilation for s between 13 and 25 GeV2

Charged hadron production via $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→}\text{h}{}^{\mathrm{\pm }}\text{X where h}{}^{\mathrm{\pm }}\text{= π}{}^{\mathrm{\pm }}\text{,}\text{K}{}^{\mathrm{\pm }}\text{,}\text{p}\text{?}$ has been measured for s values between 13 and 25 GeV². Inclusive cross sections and the evidence for scaling are presented.     

QCD predictions for four-jet final states in e+e− annihilation

We have calculated the four-jet production processes $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→q}\text{q}\text{gg}$ and $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→q}\text{q}\text{q}\text{q}$ to lowest-order QCD perturbation theory. We find that (q$\text{q}$q$\text{q}$) production is small compared to the dominant process $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→q}\text{q}\text{gg}$ which can in part be traced to the fact that the latter process is more singular as the 2- and 3-jet phase-space limits are approached. We present differential 4-jet acoplanarity distributions and compare them with non-perturbative acoplanarity distributions at maximum PETRA and PEP energies. Leading log cross-section formulae are derived for various cut-off procedures and are compared to the results of our numerical integrations. We also present results on associated heavy quark production in e⁺e^? annihilation.     

Anomalous events in e+e−→μ+μ−γ. excited states and/or new interactions?

We first show that the enhancement observed by Cello can neither be explained by real or virtual μ¹ production through μ¹μγ or μ¹μZ couplings nor by μμγγ or μμγZ contact terms, when one imposes the usual constraints from $\text{g -2, e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→γγ, Z→}\text{ll}\text{γ}$. We then propose an explanation using an eeμμ¹ contact term which is less constrained. In addition to $\text{μ}{}^1\text{→μγ}$ this leads to a direct decay $\text{μ}{}^1\text{→μee}$. Generalized to other types of fermion pairs we have here an interesting source of multifermion anomalous events.     

A search for monojet events produced by virtual Z0 bosons in e+e− annihalation at petra

A search was performed for the associated production of two different Higgs bosons via a virtual Z⁰ in e⁺e^? annihilation (e⁺e^? → h₁⁰h₂⁰) using the JADE detector at PETRA. This was motivated by the interpretation of the monojet events observed at the CERN p$\text{p}$ collider as anomalous Z⁰ decays into two neutral Higgs bosons (h₁⁰ and h₂⁰), where h₁⁰ is stable and escapes detection while h₂⁰ decays into hadrons. Single- or di-jet events with large momentum imbalance are then expected at PETRA energies. No evidence for such events was found in our data; this excludes h₂⁰ masses in the range of 1 to 21 GeV with 95% CL, if the branching fraction for Z⁰ → h₁⁰h₂⁰ is a larger than one half that for $\text{Z}{}^0\text{→ v}{}_{\mathrm{\mu }}\text{v}{}_{\mathrm{\mu }}$. The possibility that the monojets could originate from supersymmetric higgsino production from Z⁰ decay is also examined.     

Study of the photon spectrum in the decay KS0→π+π−γ

The branching ratio $\text{Λ(}\text{K}{}_{\mathrm{<mtext>S</mtext>}}{}^0\text{→π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{γ)}\text{Λ(}\text{K}{}_{\mathrm{<mtext>S</mtext>}}{}^0\text{→π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{)}$ has been determined to be (2.68±0.15)×10^?3 for photon energies $\text{E}{}_{\mathrm{\gamma }}{}^1$ greater than 50 MeV in the K_S⁰ rest frame. The decay K_S⁰→π⁺π^?γ is found to be dominated by the internal bremsstrahlung transition. The branching rato of a possible direct transition is found to be less than 0.06 × 10^?3 at 90% confidence level for $\text{E}{}_{\mathrm{\gamma }}{}^1\text{> 50}\text{MeV}$.     

An experimental study of the form factor in the decay K+ → πoe+ν

The q² variation of the factor $\text{?}{}_{\mathrm{+}}\text{(q}{}^2\text{)}$ in the decay K⁺→π⁰e⁺ν has been studied using a sample of even detected in the CERN 1.1 m³ heavy-liquid bubble chamber. The data are consistent with a linear development $\text{?}{}_{\mathrm{+}}\text{(q}{}^2\text{)=?}{}_{\mathrm{+}}\text{(0) (1+λ}{}_{\mathrm{+}}\text{q/m}{}^2{}_{\mathrm{\pi }}\text{)}$ with λ₊=0.027±0.008.     

Rotational analysis of the B3Π(0+) → X1Σ+ band systems of 35Cl35Cl and 35Cl37Cl in the chlorine afterglow emission spectrum

The B³Π(0⁺) → X¹Σ⁺ band system of Cl₂, excited by the recombination of ground state $\text{Cl}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ atoms at total pressures near 2 Torr, has been rotationally analyzed in the range 6300–9900 Å. About 30 bands, with 0 ≤ v′ ≤ 6 and 5 ≤ v″ ≤ 14, were investigated, mostly for both ³⁵Cl³⁵Cl and ³⁵Cl³⁷Cl. The band origins and rotational constants for the B state were obtained with the help of the known constants for the ground state. The principal molecular constants (cm^?1) for the B³Π(0⁺) state of ³⁵Cl³⁵Cl are as follows: T_e′ = 17 817.67(3); ω_e′ = 255.38(3); ω_e′x_e′ = 4.59(1); ω_e′y_e′ = ?0.038(8); D_e′ = 3341.17(14); B_e′ = 0.16313(3); α_e′ = 2.42(3) × 10^?3; γ_e′ = ?5.7(7) × 10^?5. The equilibrium internuclear separation is 2.4311(2) Å. The results of Briggs and Norrish on a transient absorption spectrum of Cl₂ assigned as $\text{0}{}_{\mathrm{g}}{}^{\mathrm{+}}\text{← B}{}^3\text{Π}\text{(0}{}^{\mathrm{+}}\text{)}$ are reinterpreted with the present constants.     

Measurement of the decay ϒ′→ϒπ+π−

We report the first observation of the decay $\text{?′→?π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{→}\text{l}{}^{\mathrm{+}}\text{l}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}$. The 7 events seen yield a branching ratio B(?′→?π⁺π^?)=(19±8)%. A consistent value of B=(26±13)% is obtained from the charged multiplicities of the ?′ and ? decays. Using these values we deduce Γ_tot(?′)=(31⁺¹⁰_?8) keV and B_ee(?′)=(1.8±0.5)%. Furthermore we estimate Γ(?′→gg?)=(10±5) keV in agreement with QCD predictions using vector gluons while one would expect 100 keV with scalar gluons.     

Photino-photino-photon production in e+e− annihilation

The cross section for production of single photons in the process $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→ γ}\text{γ}\text{γ}$ is calculated including selectron propagator and photino mass effects and is found to be significantly smaller than the local limit for selectron masses ? 35 GeV/c². Numerical results for the cross section are obtained as a function of selectron masses for photino masses $\text{m}{}_{\mathrm{<mtext>\gamma </mtext>}}\text{? 10}\text{GeV}\text{/c}{}^2$ and electron beam energies E = 14.5, 25, and 35 GeV appropriate to PEP, PETRA, and TRISTAN, respectively.     

Calculation of the γγ → ϱ0ϱ0 cross section at high energies

The processes with the cross sections not decreasing with energy become important at high energies. The simplest processes of this kind are γγ → V_i⁰V_j⁰ where V⁰ = ?⁰, ω, ?, ….. We calculate their cross sections in the high-energy small angle region s ? |t| ? μ². The cross section γγ → ?⁰?⁰ at high energies (s ? 10 GeV²) exceeds those of γγ → ππ, ?⁺?^? considerably. At $\text{s ? 10}{}^4\text{GeV}{}^2$ (this is the characteristic energy for the VLEPP and SLC colliders) and $\text{|t| ? 2}\text{GeV}{}^2$, the ratio $\text{(}\text{d}\text{σ/}\text{d}\text{t)(γγ → ?}{}^0\text{?}{}^0\text{)/(}\text{d}\text{σ/}\text{d}\text{t)(γγ → μ}{}^{\mathrm{+}}\text{μ}{}^{\mathrm{?}}\text{) ? 70}$.     

Inclusive spectra of electroproduced K+ mesons

We report measurements of kaon electroproduction from a hydrogen target carried out at DESY. The invariant cross section for the reaction ep → eK⁺ + anything is given as a function of the variables q², W, x, p²_⊥ and φ in the following region:

$\text{?0.5 ? q}{}^2\text{? ?0.1 GEV}{}^2\text{, 2.0 ? W ? 2.8 GEV, 0.3 ? x ? ? 1.0, p}{}^2{}_{\mathrm{\perp }}\text{? 0.25 GEV}{}^2\text{, 0° ? ø ? 360°}$

. Finally we compare our data with a quark-parton model.     

Limits on the couplings of ϱ′ (1300 Me) and rhov;″ (1700 MeV) to the photon and to the (ππ) system

The analysis of the reaction e⁺e^?→π⁺π^? measured at the e⁺e^? colliding beam machine ADONE shows that, if ?′ and ?″ exist, the cross sections compare as follows (taking the ? as the reference point): $\text{σ(}\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→ ? → π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{)}$: σ(e⁺e^? → ?′ → π⁺π^?): σ(e⁺e^? → ?″ → π⁺π^?) = 1: (7 ± 4) × 10^?3: (1 ± 5) × 10^?4. The square of the product of their couplings to the photon (γ_?) and the γγ system (g_?ππ) are derived.     

The emission spectra of H35Cl+, H37Cl+, D35Cl+, and D37Cl+ in the region 2700–4100 Å

The $\text{A}{}^2\text{Σ}{}^{\mathrm{+}}\text{-X}{}^2\text{Π}$ emission spectrum of HCl⁺ has been measured and analyzed for four isotopic combinations. These analyses extend previous work and provide rotational constants for the v = 0–2 levels of the ground state and for the v = 0–9 levels of the excited state. RKR potentials have been determined for both states, although the upper state could not be fitted precisely to such a model. Calculated relative intensities based on these potentials demonstrated that the electronic transition moment must change rapidly with lower state vibrational quantum number. Although considerable caution should be exercised in applying the concept of equilibrium constants to the $\text{A}{}^2\text{Σ}{}^{\mathrm{+}}$ state, the following are the best estimates of these constants (in cm^?1) for the $\text{X}{}^2\text{Π}$ state of H³⁵Cl⁺: B_e = 9.9406, ω_e = 2673.7, A_e = ? 643.7, and $\text{r}{}_{\mathrm{e}}\text{= 1.315}\text{A}\text{?}$. For the $\text{A}{}^2\text{Σ}{}^{\mathrm{+}}$ state of H³⁵Cl: T_e = 28 628.08, B_e ～ 7.505, ω_e ～ 1606.5, and $\text{r}{}_{\mathrm{e}}\text{= 1.514}\text{A}\text{?}$.     

Precise measurement of Γ(Λ0 → p + e− + ν)/Γ(Λ0 → p + π−)

Based on a sample of 10 000 events of the decay $\text{Λ}{}^0\text{→ p + e}{}^{\mathrm{?}}\text{+}\text{ν}\text{,}\text{the ratio}\text{Γ(Λ}{}^0\text{→ pe}\text{ν}\text{)/Γ(Λ}{}^0\text{→ pπ}{}^{\mathrm{?}}\text{)}$ is found to be (1.313 ± 0.024) × 10^?3. From this, the absolute rate for the process is calculated to be (3.204 ± 0.068) × 10⁶ s^?1 .     

Determination of molecular constants of nitric oxide from (1-0), (2-0), (3-0) bands of the 15N16O and 15N18O isotopic species

The (1-0), (2-0), and (3-0) transitions of ¹⁵N¹⁶O and ¹⁵N¹⁸O are investigated. The wavenumbers of the rotation-vibration lines are reported for the overtone bands and the ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{-}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ (1-0) subband. It is shown that in the data reduction it is advantageous to calculate first merged spectroscopic constants ignoring the Λ-type doubling. The vibrational constants ω_e, ω_ex_e, ω_ey_e and the vibrational dependence of the rotational constants are determined. The study of ¹⁵N¹⁸O allows the determination of the equilibrium values of the centrifugal distortion correction A_De to the spin-orbit constant and of the spin-rotation constant γ_e from the isotopic invariance of the ratios $\text{A}{}_{\mathrm{<mtext>De</mtext>}}\text{B}{}_{\mathrm{<mtext>e</mtext>}}$ and $\text{γ}{}_{\mathrm{<mtext>e</mtext>}}\text{B}{}_{\mathrm{<mtext>e</mtext>}}$. It is found that $\text{A}{}_{\mathrm{<mtext>De</mtext>}}\text{B}{}_{\mathrm{<mtext>e</mtext>}}\text{= (?3.9 ± 1.3) × 10}{}^{\mathrm{?6}}$ and $\text{γ}{}_{\mathrm{<mtext>e</mtext>}}\text{B}{}_{\mathrm{<mtext>e</mtext>}}\text{= (?4.00 ± 0.05) × 10}{}^{\mathrm{?3}}$.     

The ground state of methane 12CH4 through the forbidden lines of the ν3 band

High resolution spectra of the ν₃ band of methane, ¹²CH₄, were recorded by using a “third generation vacuum Fourier interferometer”; a large pressure range (from 0.009 to 10 Torr) with a sample path fixed at eight meters was used, enabling observation of transitions with intensity ratios as low as $\text{1}\text{10 000}$. More than 350 forbidden transitions of the ν₃ band, including about 125 transitions of the Q⁺ branch, were unambiguously identified. Of the 277 transitions retained for computations, one-hundred have 11 ≤ J ≤ 16. From combination difference relations using pairs of transitions having the same upper state energy level (forbidden-allowed and forbidden-forbidden pairs were used), 276 independent differences between ground state energy levels could be determined with uncertainties of about 0.001 cm^?1.These data yielded the following values for the ground state structure constants of ¹²CH₄ along with their standard deviations (in cm^?1): $\text{β}{}^{\mathrm{o}}\text{hc}\text{=5.2410356±0.0000096}$, $\text{γ}{}^{\mathrm{o}}\text{hc}\text{=(?1±0.00074) 10}{}^{\mathrm{?4}}$, $\text{π}{}^{\mathrm{o}}\text{hc}\text{=(5.78±0.18) 10}{}^{\mathrm{?9}}$, $\text{?}{}^{\mathrm{o}}\text{hc}\text{=(?1.4485±0.0023) 10}{}^{\mathrm{?6}}$, $\text{?}{}^{\mathrm{o}}\text{hc}\text{=(1.768±0.126) 10}{}^{\mathrm{?10}}$, $\text{ξ}{}^{\mathrm{o}}\text{hc}\text{=(?1.602±0.067) 10}{}^{\mathrm{?11}}$, Thus, for the first time, the scalar constant π⁰ has been evaluated and ir values have been obtained for the two tetrahedral constants ?⁰ and ξ⁰; furthermore, these values are in very good agreement with the ones recently determined from radiofrequency data, i.e., in cm^?1: $\text{?}{}^{\mathrm{o}}\text{hc}\text{=(?1.45061±0.00014) 10}{}^{\mathrm{?6}}$, $\text{?}{}^{\mathrm{o}}\text{hc}\text{=(1.7634±0.0068) 10}{}^{\mathrm{?10}}$, $\text{ξ}{}^{\mathrm{o}}\text{hc}\text{=(?1.5432±0.0040) 10}{}^{\mathrm{?11}}$ From these values, the 276 differences can be reproduced with an overall rms deviation equal to 0.0009 cm^?1.Finally, the ground state energies of ¹²CH₄ have been calculated for J ≤ 16.     

The electronic isotope shift in the A2Π-X2Σ+ bands of BeH,BeD and BeT

The 0-0, 1-1, 2-2, and 3-3 bands of the A²Π-X²Σ⁺ transition of the tritiated beryllium monohydride molecule have been observed at 5000 Å in emission using a beryllium hollow-cathode discharge in a He + T₂ mixture. The rotational analysis of these bands yields the following principal molecular constants.

$\text{A}{}^2\text{Π:}\text{B}{}_{\mathrm{e}}\text{= 4.192}\text{cm}{}^{\mathrm{?1}}\text{; r}{}_{\mathrm{e}}\text{= 1.333}\text{A}\text{?}$

$\text{X}{}^2\text{Σ:}\text{B}{}_{\mathrm{e}}\text{= 4.142}\text{cm}{}^{\mathrm{?1}}\text{; r}{}_{\mathrm{e}}\text{= 1.341}\text{A}\text{?}$

$\text{ω}{}_{\mathrm{e}}\text{′ ? ω}{}_{\mathrm{e}}\text{″ = 16.36}\text{cm}{}^{\mathrm{?1}}\text{; ω}{}_{\mathrm{e}}\text{′X}{}_{\mathrm{e}}\text{′ ? ω}{}_{\mathrm{e}}\text{″X}{}_{\mathrm{e}}\text{″ = 0.84}\text{cm}{}^{\mathrm{?1}}$

From the pure electronic energy difference (E_Π - E_Σ)_BeT = 20 037.91 ± 1.5 cm^?1 and the corresponding previously known values for BeH and BeD, the following electronic isotope shifts are derived

$\text{ΔE}{}_{\mathrm{e}}{}^{\mathrm{i}}\text{(}\text{BeH}\text{?}\text{BeT}\text{) = ?4.7 ≠ 1.5}\text{cm}{}^1\text{, ΔE}{}_{\mathrm{e}}{}^{\mathrm{i}}\text{(}\text{BeH}\text{?}\text{BeT}\text{) = ?1.8 ≠ 1.5}\text{cm}{}^1$

and related to the theoretical approach given by Bunker to the problem of the breakdown of the Born-Oppenheimer approximation.