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Andreev V.,RAS Lebedev Physical Institute | Baghdasaryan A.,Yerevan Physics Institute | Begzsuren K.,Institute of Physics and Technology of the Mongolian Academy of science | Belousov A.,RAS Lebedev Physical Institute | And 152 more authors.
Journal of High Energy Physics | Year: 2015

Abstract: The cross section of the diffractive process e+p → e+Xp is measured at a centre-of-mass energy of 318 GeV, where the system X contains at least two jets and the leading final state proton p is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction with photon virtualities Q2< 2 GeV2 and in deep-inelastic scattering with 4 GeV2< Q2< 80 GeV2. The results are compared to next- to-leading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deep-inelastic scattering. © 2015, The Author(s).


Andreev V.,RAS Lebedev Physical Institute | Baghdasaryan A.,Yerevan Physics Institute | Begzsuren K.,Institute of Physics and Technology of the Mongolian Academy of science | Belousov A.,RAS Lebedev Physical Institute | And 148 more authors.
Journal of High Energy Physics | Year: 2015

Abstract: A measurement is presented of single- and double-differential dijet cross sections in diffractive deep-inelastic ep scattering at HERA using data collected by the H1 experiment corresponding to an integrated luminosity of 290 pb−1. The investigated phase space is spanned by the photon virtuality in the range of 4 < Q2< 100 GeV2 and by the fractional proton longitudinal momentum loss x< 0.03. The resulting cross sections are compared with next-to-leading order QCD predictions based on diffractive parton distribution functions and the value of the strong coupling constant is extracted. © 2015, The Author(s).


Alexa C.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Andreev V.,RAS Lebedev Physical Institute | Baghdasaryan A.,Yerevan Physics Institute | Baghdasaryan S.,Yerevan Physics Institute | And 183 more authors.
European Physical Journal C | Year: 2013

Cross sections for elastic and proton-dissociative photoproduction of J/ψ mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies √s≈318 GeV and √s≈225 GeV, corresponding to integrated luminosities of L = 130 pb-1 and L = 10.8 pb -1, respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25


Alexa C.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Andreev V.,RAS Lebedev Physical Institute | Baghdasaryan A.,Yerevan Physics Institute | Baghdasaryan S.,Yerevan Physics Institute | And 173 more authors.
European Physical Journal C | Year: 2013

Charged particle production in deep-inelastic ep scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5 < Q2 < 100 GeV2, and small values of Bjorken-x, 10-4 < x < 10-2. The analysis is performed in the hadronic centre-of-mass system. The charged particle densities are measured as a function of pseudorapidity (η*) and transverse momentum (pT*) in the range 0 < η* < 5 and 0 < pT* < 10 GeV in bins of x and Q2. The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions. © 2013 The Author(s).


Andreev V.,RAS Lebedev Physical Institute | Baghdasaryan A.,Yerevan Physics Institute | Begzsuren K.,Institute of Physics and Technology of the Mongolian Academy of science | Belousov A.,RAS Lebedev Physical Institute | And 146 more authors.
European Physical Journal C | Year: 2015

Inclusive jet, dijet and trijet differential cross sections are measured in neutral current deep-inelastic scattering for exchanged boson virtualities using the H1 detector at HERA. The data were taken in the years 2003 to 2007 and correspond to an integrated luminosity of. Double differential Jet cross sections are obtained using a regularised unfolding procedure. They are presented as a function of and the transverse momentum of the jet, and as a function of and the proton’s longitudinal momentum fraction, carried by the parton participating in the hard interaction. In addition normalised double differential jet cross sections are measured as the ratio of the jet cross sections to the inclusive neutral current cross sections in the respective bins of the jet measurements. Compared to earlier work, the measurements benefit from an improved reconstruction and calibration of the hadronic final state. The cross sections are compared to perturbative QCD calculations in next-to-leading order and are used to determine the running coupling and the value of the strong coupling constant as. © 2015, The Author(s).


Andreev V.,RAS Lebedev Physical Institute | Baghdasaryan A.,Yerevan Physics Institute | Baghdasaryan S.,Yerevan Physics Institute | Begzsuren K.,Institute of Physics and Technology of the Mongolian Academy of science | And 157 more authors.
European Physical Journal C | Year: 2014

Inclusive ep double differential cross sections for neutral current deep inelastic scattering are measured with the H1 detector at HERA. The data were taken with a lepton beam energy of 27.6 GeV and two proton beam energies of Ep = 460 and 575 GeV corresponding to centre-of-mass energies of 225 and 252 GeV, respectively. The measurements cover the region of 6.5 × 10-4 ≤ x ≤ 0.65 for 35 ≤ Q2 ≤ 800 GeV2 up to y = 0.85. The measurements are used together with previously published H1 data at Ep = 920 GeV and lower Q2 data at Ep = 460, 575 and 920 GeV to extract the longitudinal proton structure function FL in the region 1.5 ≤ Q2 ≤ 800 GeV2. © 2014 The Author(s).


Andreev V.,RAS Lebedev Physical Institute | Baghdasaryan A.,Yerevan Physics Institute | Begzsuren K.,Institute of Physics and Technology of the Mongolian Academy of science | Belousov A.,RAS Lebedev Physical Institute | And 143 more authors.
European Physical Journal C | Year: 2016

A first measurement is presented of exclusive photoproduction of ρ0 mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a centre-of-mass energy of √s=319 GeV and correspond to an integrated luminosity of 1.16 pb-1. The ρ0 mesons with transverse momenta (Formula presented.) GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum, (Formula presented.), are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality (Formula presented.), the total energy of the photon–proton system (Formula presented.) GeV and the polar angle of the leading neutron (Formula presented.)0.75 mrad. The cross section of the reaction (Formula presented.) is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a ρ0 meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, (Formula presented.), is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction (Formula presented.). © 2016, The Author(s).


Andreev V.,RAS Lebedev Physical Institute | Baghdasaryan A.,Yerevan Physics Institute | Begzsuren K.,Institute of Physics and Technology of the Mongolian Academy of science | Belousov A.,RAS Lebedev Physical Institute | And 154 more authors.
European Physical Journal C | Year: 2014

Measurements of normalised cross sections for the production of photons and neutrons at very small angles with respect to the proton beam direction in deep-inelastic ep scattering at HERA are presented as a function of the Feynman variable xF and of the centre-of-mass energy of the virtual photon-proton system W. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 131 pb-1. The measurement is restricted to photons and neutrons in the pseudorapidity range η > 7.9 and covers the range of negative four momentum transfer squared at the positron vertex 6 < Q2 < 100 GeV2, of inelasticity 0.05 < y < 0.6 and of 70 < W < 245 GeV. To test the Feynman scaling hypothesis the W dependence of the xF dependent cross sections is investigated. Predictions of deep-inelastic scattering models and of models for hadronic interactions of high energy cosmic rays are compared to the measured cross sections. © 2014 The Author(s).

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