V.I. Genchev

A high statistics measurement of the proton structure functions F2(x, Q2) and R from deep inelastic muon scattering at high Q2

Abstract We present results on a high statistics study of the proton structure functions F 2 ( x , Q 2 ) and R = σ L / σ T measured in deep inelastic scattering of muons on a hydrogen target. The analysis is based on 1.8 × 10 6 events after all cuts, recorded at beam energies of 100, 120, 200 and 280 GeV and covering a kinematic range 0.06 ⩽ x ⩽ 0.80 and 7 GeV 2 ⩽ Q 2 ⩽260 GeV 2 . At small x , we find R to be different from zero in agreement with predictions of perturbative QCD.

A high statistics measurement of the deuteron structure functions F2(x, Q2) and R from deep inelastic muon scattering at high Q2

Abstract We present results on a high statistics study of the nucleon structure functions F2(x, Q2) and R=σL/σT measured in deep inelastic scattering of muons on a deuterium target. The analysis is based on 8×105 events after all cuts, recorded at beam energies of 120, 200 and 280 GeV in the kinematic range 0.06⩽ × ⩽0.80 and 8GeV2⩽Q2⩽260GeV2. Scaling violations observed in the data are in agreement with predictions of perturbative QCD and allow to determine the QCD mass scale parameter Λ.

A comparison of the structure functions F2 of the proton and the neutron from deep inelastic muon scattering at high Q2

Abstract High statistics data on the structure functions F2 of the proton and the deutron measured with the same apparatus in deep inelastic muon scattering are used to study the ratio of structure functions of neutron and proton F2n/F2p and their difference F2p-F2n. Both measurements are consistent with predictions of the quark-parton model and of QCD.

Test of QCD and a measurement of Λ from scaling violations in the proton structure function F2(x, Q2) at high Q2

Abstract Scaling violations in the proton structure function F 2 ( x , Q 2 ) measured with high statistics in deep inelastic scattering of muons on a hydrogen target are compared to predictions of perturbative QCD. Excellent agreement is observed with numerical solutions of the evolution equations in leading and next-to-leading order. The QCD mass scale parameter Λ is determined from these data both in a flavour nonsinglet approximation and with a complete flavour singlet and nonsinglet treatment. An estimate of the gluon distribution in the proton is given.

A study of the semileptonic decays of neutral kaons

Dalitz plots of 74 000 Ke30 and 150 000 Kμ30 decays have been investigated to measure the t-dependence of the form factors ƒ+(t) and ƒ(t) describing the vector contribution to the decay matrix element. The decays were registered by a wire spark chamber spectrometer in the neutral beam of the Serpukhov accelerator. An analysis using a linear expansion of the form factors gives the slopes: λe+=0.0306±0.0034 for the Ke30 decays and λμ+ = 0.0427±0.0044, λ0 = 0.0341± 0.0067 for the Kμ30 decays. The ratio of the form factors ƒ− to ƒ+ has been found to be ξ(0)=ƒ−(0)/ƒ+(0)=−0.10±0.09. These results are compared with the relevant theoretical models. Together with the data of other experiments in which the parameters of muon and electron interactions are measured, the observed difference between λ+μ and λ+e gives some indication of the violation of μ-e universality.

KL0-KS0 transmission regeneration on hydrogen

The energy dependence of the modulus and phase of the KL0-KS0 regeneration amplitude on hydrogen in the range of 14–50 GeV has been investigated at the Serpukhov 70 GeV accelerator. It has been established that the modulus of the modified regeneration amplitude decreases with increasing momentum as 2|ƒ210(p)|/k = (0.84 ± 0.42) · p−0.50±0.15 mb. The amplitude phase is energy-independent and its mean value is ϕ210 = −132° ± 5°. The results obtained are compared with other experiments and with predictions of different theoretical models.

Neutral kaon regeneration on carbon in a momentum region of 16–40 GeV/c

Abstract The modulus and the phase of the K L o −K S o regeneration amplitude on carbon have been measured. In a momentum range of 16–40 GeV/ c the phase is constant within experimental error bars and coincides with the regeneration phase on hydrogen. Both the modulus and the phase of the regeneration amplitude on carbon are in agreement with optical model predictions.

The coherent K L 0 C → K S 0 C regeneration at high energies

New experimental results on the coherentKL0C →KS0C regeneration in the momentum range 10≦p≦30 GeV/c are presented. For the quantity (f0−¯f0/k (where f0 and¯f0 are theK‡C and¯K0C forward scattering amplitudes andk is the wave number) we have obtained: arg (f0−¯f0)/k=−126‡±14‡ and ¦(f0−¯f0/k¦∼ ∼p−0.62±0.14 These results are well described by a simple Regge pole model including only the (Ω-trajectory exchange in thet-channel with the intercept αω(0) close to 0.4.

Study of nuclear effects in nucleon structure functions up to and beyond the kinematic limit

An experiment on deep inelastic muon nucleon scattering in order to study the x-dependence of nucleon structure functions and their ratios over a range ofQ2=50–200 GeV2 andx= =0·4–2·0 is proposed. Such measurements performed on a number of nuclei with atomic weights from 2 to 207 provide new information for detailed studies of the EMC effect and test models explaining thex-behaviour of the nucleon structure functions and their ratios. The measurements are decisive for the proof that a quark-parton model of the nucleus describes adequately nuclear structure probed at high energies. The upgraded high luminosity BCDMS spectrometer with improved resolution in transferred energyν can be used for the measurements.

A study of the formfactors in the Kμ3O decays

Abstract The analysis of 82386 selected K μ3 decays has been performed. Two solutions both for the vector and scalar formfactors have been obtained, and for each solution the validity of linear approximation is shown. One of the solutions which agrees with the μ-e universality hypothesis, gives the following values for the linear expansion parameters: λ + = 0.046 ± 0.008, λ O = 0.024 ± 0.011.