N. M. Agababyan

Joint Institute for Nuclear Research, Dubno, Moskovskaya, Russia

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Publications (84)44.1 Total impact

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    ABSTRACT: First experimental data on the inclusive yields of Delta^{0}(1232) and Delta^{+}(1232) isobars in neutrino-induced reactions are obtained. Their total yields in neutrino-nucleon interactions, 0.145+-0.055 and 0.182+-0.054, respectively, exceed the value of 0.091+-0.015 obtained recently for the Delta^{++}(1232) state. The data for the all three states of Delta(1232) cannot be reproduced by the LEPTO6.5 model. The fractions of \pi^0, \pi^- and \pi^+ mesons originating from the decay of lights baryonic and mesonic resonances are estimated to be, respectively 56.6+-9.6%, 39.5+-6.6% and 27.7+-3.2%.
    11/2013;
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    ABSTRACT: For the first time, the inclusive neutrinoproduction of \Delta^{++}(1232) from nuclei is investigated. The total yield of $\Delta^{++}(1232) in neutrino-nuclear interaction is found to be \ < n\ >_{\nu A} = 0.080\pm0.011, being compatible with \ < n\ >_{\nu N} = 0.091\pm0.013 inferred for neutrino-nucleon interactions. It is shown that the \Delta^{++}(1232) inclusive spectra on variables x_F, z and the isobar total momentum for \nu A interactions are shifted toward lower values respective to those for \nu N interactions, that can be caused by secondary intranuclear collision processes. No idication on a significant nuclear absorption of \Delta^{++}(1232) leading to its disappearance is found.
    03/2013;
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    ABSTRACT: For the first time, the total yield and inclusive spectra of the $\Delta^{++}(1232)$isobar are measured in $\nu p$ and $\nu n$ charged-current interactions. An indication is obtained that the $\Delta^{++}(1232)$ production mainly results from the neutrino scattering on the valence d- quark of the target nucleon. The total yield of $\Delta^{++}(1232)$ in $\nu p$ interactions is compatible with that measured in hadronic interactions of the same net charge and net baryonic number. The yield of $\Delta^{++}(1232)$ in $\nu n$ interactions is significantly suppressed as compared to the case of the proton target. The form of the squared transverse momentum distributions, both in $\nu p$ and $\nu n$ interactions, is found to be compatible with the available data on the neutrinoproduction of $\Lambda$ hyperon. The experimental data are compared with the LEPTO6.5 model predictions.
    06/2012;
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    ABSTRACT: For the first time, the nuclear attenuation of three hadron systems is studied in neutrino-induced reactions using the data obtained with SKAT bubble chamber. The strongest attenuation (R_3 ~ 0.6) is observed for a system carrying an overwhelming fraction of the current quark energy, as well as for a system with the smallest effective mass. An indication is obtained that the correlation effects in the nuclear attenuation play only a minor role. The experimental data are compared with predictions of the quark string fragmentation model.
    08/2011;
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    ABSTRACT: The charged current neutrino production of {phi} and D{sub s}{sup +} mesons is studied, using the data obtained with the SKAT bubble chamber exposed to the Serpukhov accelerator neutrino beam. It is found that the {phi} production occurs predominantly in the forward hemisphere of the hadronic c.m.s. (at x{sub F} > 0, x{sub F} being the Feynman variable), with the mean yield strongly exceeding the expected yield of directly produced {phi} mesons and varying from Left-Pointing-Angle-Bracket n{sub {phi}}(x{sub F} s 0) Right-Pointing-Angle-Bracket = (0.92 {+-} 0.34) Multiplication-Sign 10{sup -2} at W > 2 GeV up to (1.23 {+-} 0.53) Multiplication-Sign 10{sup -2} at W > 2.6 GeV and (1.44 {+-} 0.69) Multiplication-Sign 10{sup -2} at W > 2.9 GeV, W being the invariant mass of the hadronic system. For the first time, the inclusive yield of leading D{sub s}{sup +} mesons carrying more than z = 0.85 of the current c-quark energy is estimated: Left-Pointing-Angle-Bracket n{sub Ds}{sup +}(z > 0.85, W > 2.9 GeV) Right-Pointing-Angle-Bracket = (6.64 {+-} 1.91) Multiplication-Sign 10{sup -2}. It is shown that the shape of measured {phi} meson differential spectrum on xF is reproduced by that expected from the D{sub s}{sup +} {yields} {phi}X decays. An indication was obtained that this expected spectrum underestimates the measured {phi} yield.
    Physics of Atomic Nuclei 02/2011; 74(2). · 0.54 Impact Factor
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    ABSTRACT: The total yields of the all well established light meson resonances (up to the {phi}(1020) meson) are estimated in neutrino-nucleus charged current interactions at Left-Pointing-Angle-Bracket E{sub {nu}} Right-Pointing-Angle-Bracket Almost-Equal-To 10 GeV, using the data obtained with SKAT bubble chamber. The yield of {phi} meson in neutrino production is obtained for the first time. For some resonances, the yields in the forward and backward hemispheres in the hadronic c.m.s. are also extracted. From the comparison of the obtained and available higher-energy data, an indication is obtained that the resonance yields rise almost linearly as a function of the mass W of the neutrino produced hadronic system. The fractions of pions originating from the light resonance decays are inferred.
    Physics of Atomic Nuclei 02/2011; 74(2). · 0.54 Impact Factor
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    ABSTRACT: For the first time, the nuclear effects in the reaction \nu p -> \mu^- p \pi^+ on bound protons are investigated at E_\nu = 9 GeV and the effective atomicweight A = 21 of the composite nuclear target using the data obtained with SKAT bubble chamber. The observed nuclear effects are explained by the Fermi-motion of the target proton and secondary elastic scattering of neutrinoproduced hadrons on intranuclear neutrons. The probability of any intranuclear interaction of neutrinoproduced hadrons is extracted: P_int = 0.40+-0.13, while the probability of interactions occurring only via elastic scattering on intranuclear neutrons is estimated to be P_c = 0.14+-0.05. A clear evidence of the \Delta^{++}(1232) and an indication on the \Delta^{++}(1620) isobar states production are observed with the mean yields, respectively, 0.57+-0.09 and 0.40+-0.26 (the latter being corrected for the p \pi^+ decay fraction). The mean yield of \Delta^{++}(1232) is by 1.61+-0.25 times smaller than expected for the reaction on the hydrogen target, thus indicating on its rather strong nuclear absorption.
    01/2011;
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    ABSTRACT: The nuclear medium influence on the dihadron neutrino charged current production is investigated using the data obtained with SKAT bubble chamber. An indication is obtained that the nuclear attenuation of the dihadron production is more expressed for kinematically closest hadron pairs. The experimental data are compared with predictions of the string model.
    Physics of Atomic Nuclei 01/2011; 74(2):246-252. · 0.54 Impact Factor
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    ABSTRACT: The production of charged ρ mesons on nuclei and nucleons is investigated in charged current neutrino interactions at moderate energies (〈E 〉 ≈ 10 GeV), using the data obtained with SKAT bubble chamber. No strong nuclear effects are observed in ρ + and ρ − production. The fractions of charged and neutral pions originating from ρ decays are obtained and compared with higher-energy data. From analysis of the obtained and available data on ρ + and K*+(892) neutrino production, the strangeness suppression factor is extracted: λ s = 0.18 ± 0.03. Estimation is obtained for cross section of coherent ρ + neutrino production on nuclei.
    Physics of Atomic Nuclei 01/2011; 74(2):221-228. · 0.54 Impact Factor
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    ABSTRACT: The nuclear effects in ρ 0-meson neutrino production are investigated using the data obtained with the SKAT bubble chamber. The nuclear-medium influence on the ρ 0 total yield and inclusive distributions on z = E ρ /v and Feynman x F variable is found to be approximately the same as for pions. It is shown that these distributions with increasing A tend to shift toward smaller values of z and x F, thus indicating an increasing role of secondary intranuclear interactions. The predictions of a simple model incorporating the latter are found to be in qualitative agreement with experimental data.
    Physics of Atomic Nuclei 10/2007; 70(11):1898-1903. · 0.54 Impact Factor
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    ABSTRACT: Using the data obtained with the SKAT bubble chamber, the total yields of K*(892){sup +}, {sigma}{sup +}(1385), and {sigma}{sup 0} are estimated for the first time in neutrino-induced reactions at moderate energy <E{sub v}> = 10.4 GeV. It is shown that the recently observed enhancement of the K{sup 0} and {lambda} yields in vA interactions as compared to vN interactions is contributed only slightly by the K*(892){sup +} and {sigma}{sup +}(1385) production. The contribution of resonances to the K{sup 0} and {lambda} yields is found to be in qualitative agreement with higher energy (<E{sub v}> {>=} 40 GeV) data. It is shown that the energy dependence of the K*(892){sup +} mean multiplicity in vN interactions is approximately linear in the range of <E{sub v}> {approx} 10-60 GeV, while that for {sigma}{sup 0} in vA interactions (A = 20-21) is approximately logarithmic in the range of <E{sub v}> {approx} = 10-150 GeV.
    Physics of Atomic Nuclei 10/2007; 70(10). · 0.54 Impact Factor
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    ABSTRACT: The A dependence of the production of K 0 and Λ is investigated for the first time in neutrino-nuclear reactions using the data obtained with the SKAT bubble chamber. An exponential parametrization (∼A β) of the particle yields results in $\beta _{V^0 } $ = 0.20 ± 0.05 for V 0 particles (K 0 and Λ), while for π − mesons the A dependence is much weaker ( $\beta _{\pi ^ - } $ = 0.068 ± 0.007). A nuclear enhancement of the ratio K 0/π − is found; this ratio increases from 0.055 ± 0.013 for vN interactions up to 0.070 ± 0.011 at A ≈ 21 and 0.099 ± 0.011 at A ≈ 45. It is observed that the multiplicity rise of V 0 occurs predominantly in the backward hemisphere of the hadronic system. It is shown that the A dependence of the Λ0 and π − yields can be reproduced in the framework of a model incorporating the secondary intranuclear interactions of pions originating from the primary vN interactions.
    Physics of Atomic Nuclei 10/2007; 70(10). · 0.54 Impact Factor
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    ABSTRACT: Quasielastic muon-neutrino scattering on nuclei of propane-Freon mixture at energies in the range E v < 1 GeV is studied. The multiplicity, momentum, and emission-angle distributions of final protons are measured along with the dependence of the mean values for these distributions on the neutrino energy in the range 0.2 < E v < 1 GeV.
    Physics of Atomic Nuclei 09/2007; 70(10):1725-1730. · 0.54 Impact Factor
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    ABSTRACT: The A - dependence of rho^0 meson production in neutrino-induced reactions is investigated for the first time, using the data obtained with SKAT bubble chamber. The nuclear medium influence on the rho^0 total yield and inclusive distributions (on z = E_rho/nu and Feynman x_F variables) is found to be approximately the same as for pions. It is shown, that these distributions, with increasing A, tend to shift toward smaller values of z and x_F, thus indicating on an increasing role of secondary intranuclear interactions. The predictions of a simplified model incorporating the latter are found to be in qualitative agreement with experimental data.
    01/2006;
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    ABSTRACT: The influence of nuclear effects on the production of neutral strange particles (V 0) is investigated using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam (with E v =3−30 GeV) at the Serpukhov accelerator. The mean multiplicity of V 0 particles in nuclear interactions, ánV0 ñA = 0.092 ±0.010\langle n_{V^0 } \rangle _A = 0.092 \pm 0.010 , is found to exceed significantly that in “quasideuteron” interactions, ánV0 ñD = 0.063 ±0.013\langle n_{V^0 } \rangle _D = 0.063 \pm 0.013 . The ratio of rV0 = ánV0 ñA/ánV0 ñD = 1.46 ±0.23\rho _{V^0 } = \langle n_{V^0 } \rangle A/\langle n_{V^0 } \rangle _D = 1.46 \pm 0.23 is larger than that for π− mesons, rp- = 1.10 ±0.03\rho _{\pi ^ - } = 1.10 \pm 0.03 . It is shown that the multiplicity gain of V 0 particles can be explained by intranuclear interactions of produced pions.
    Physics of Atomic Nuclei 12/2005; 69(1):35-38. · 0.54 Impact Factor
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    ABSTRACT: The characteristics of the charged-current neutrino—nuclear interactions are investigated for the first time at E ν = 1–3 GeV using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam at the Serpukhov accelerator. The E ν dependence of the mean multiplicities of different types of secondary particles and their multiplicity, momentum, and angular distributions are measured.
    Physics of Atomic Nuclei 08/2004; 70(11). · 0.54 Impact Factor
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    ABSTRACT: The influence of nuclear effects on the production of neutral strange particles ($V^{\circ}$) is investigated using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam (with $E_{\nu}$ = 3-30 GeV) at Serpukhov accelerator. The measured mean multiplicity of $V^{\circ}$ particles in nuclear interactions, ${<n_{V^{\circ}}>}_A$ = 0.096$\pm$0.011, is found to exceed significantly that in 'quasinucleon' interactions, ${<n_{V^{\circ}}>}_N$ = 0.059$\pm$0.012. The ratio of ${\rho}_{V^{\circ}}$ =${<n_{V^{\circ}}>}_A/{<n_{V^{\circ}}>}_N$ =1.61$\pm$0.23 is larger than that for $\pi^{-}$ mesons, ${\rho}_{\pi^-}$ = 1.10$\pm$0.03. It is shown that a dominant part of the multiplicity gain of $V^{\circ}$ particles can be explained by intranuclear interactions of produced pions.
    05/2004;
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    ABSTRACT: The influence of nuclear effects on the transverse momentum $(p_T)$ distributions of neutrinoproduced hadrons is investigated using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam (with $E_{\nu}$ = 3-30 GeV) at Serpukhov accelerator. Dependences of $<p_T^2>$ on the kinematical variables of inclusive deep-inelastic scattering and of the produced hadrons are measured. It has been observed, that the nuclear effects cause an enhancement of $<p_T^2>$ of hadrons (more pronounced for the positively charged ones) produced in the target fragmentation region at low invariant mass of the hadronic system (2 $< W <$ 4 GeV) or at low energies transferred to the current quark (2 $< \nu < 9$ GeV). At higher $W$ or $\nu$, no influence of nuclear effects on $<p_T^2>$ is observed. Measurement results are compared with predictions of a simple model, incorporating secondary intranuclear interactions of hadrons (with a formation length extracted from the Lund fragmentation model), which qualitatively reproduces the main features of the data.
    Physics of Atomic Nuclei 11/2003; · 0.54 Impact Factor
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    ABSTRACT: The inclusive spectra of hadrons are measured with the aid of the SKAT propane-freon bubble chamber irradiated with a beam of 3-to 30-GeV neutrinos from the Serpukhov accelerator. The resulting data indicate that the intranuclear absorption of leading quark-fragmentation products is enhanced as the energy transfer to the quark involved decreases or as the quark-energy fraction z acquired by the product hadron increases. An analysis of the data on the basis of the color-string model reveals that the cross section for the intranuclear absorption of positively charged hadrons that are characterized by z values in the range between 0.7 and 0.9 is close to the inelastic cross section for pion-nucleon interaction.
    Physics of Atomic Nuclei 06/2003; 66(7):1310-1318. · 0.54 Impact Factor
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    ABSTRACT: The A dependence of charged-particle spectra in π +, K +, and p interactions with Al and Au targets at 250 GeV/c are presented and compared to predictions of the Quark-Gluon String Model (QGSM). It is shown that the A dependence of invariant inclusive charged-particle spectra on the Feynman variable x is very weak between Al and Au targets. The QGSM shows a larger difference between fast-particle spectra for both Al and Au targets and different beam particles. The QGSM prediction for the leading-particle spectrum over an energy range from 250 GeV to 10 TeV in pAu(Pb) reactions is in a reasonable agreement with the results of NA22 data and a cosmic-ray experiment.
    Physics of Atomic Nuclei 12/2002; 66(1):114-122. · 0.54 Impact Factor