S. Kulagin | Institute for Nuclear Research, Russian Academy of Sciences (original) (raw)
Papers by S. Kulagin
Physical Review Letters, 1985
We study the European Muon Collaboration effect within the conventional nuclear theory using the ... more We study the European Muon Collaboration effect within the conventional nuclear theory using the free-nucleon structure function. It is shown that qualitative agreement with the experiment can be obtained by taking into account the momentum (Fermi motion) and the energy distributions of nucleons in nuclei.
Physical Review Letters, 1986
Physical Review D, 2004
W e present resul ts ofa perturbati ve Q C D anal ysi s ofdeep i nel asti c m easurem ents ofboth... more W e present resul ts ofa perturbati ve Q C D anal ysi s ofdeep i nel asti c m easurem ents ofboth the deuteron and proton structure functi ons. W e eval uate the theoreti cal uncertai nty associ ated to nucl ear e ects i n the deuteron, and we extract si m ul taneousl y the i sospi n depedendence of: i) the hi gher tw i sts term s;ii) the rati o ofthe l ongi tudi nalto transverse cross secti ons,R = L = T ; iii) the rati o ofthe neutron to proton structure functi ons,F n 2 =F p 2 . T he extracti on of the l atter, i n parti cul ar, has been at the center of an i ntense debate. Its accurate determ i nati on i s cruci al both theoreti cal l y and for the i nterpretati on of the m ore preci se neutri no experi m ents i ncl udi ng the new l y pl anned hi gh i ntensi ty 50 G eV proton synchrotron.
Physical Review C, 1994
We present a unified description of nuclear deep inelastic scattering (DIS) over the whole region... more We present a unified description of nuclear deep inelastic scattering (DIS) over the whole region 0 < x < 1 of the Bjorken variable. Our approach is based on a relativistically covariant formalism which uses analytical properties of quark correlators. In the laboratory frame it naturally incorporates two mechanisms of DIS: (I) scattering from quarks and antiquarks in the target and (II) production of quark-antiquark pairs followed by interactions with the target. We first calculate structure functions of the free nucleon and develop a model for the quark spectral functions. We show that mechanism (II) is responsible for the sea quark content of the nucleon while mechanism (I) governs the valence part of the nucleon structure functions. We find that the coherent interaction ofqq pairs with nucleons in the nucleus leads to shadowing at small x and discuss this effect in detail. In the large x region DIS takes place mainly on a single nucleon. There we focus on the derivation of the convolution model. We point out that the off-shell properties of the bound nucleon structure function give rise to sizable nuclear effects.
Physical Review C, 2007
The charged-current quasi-elastic scattering of muon neutrinos on oxygen target is computed for n... more The charged-current quasi-elastic scattering of muon neutrinos on oxygen target is computed for neutrino energies between 200 MeV and 2.5 GeV using the relativistic distortedwave impulse approximation with relativistic optical potential, which was earlier successfully applied to describe electron-nucleus data. We study both neutrino and electron processes and show that the reduced exclusive cross sections for neutrino and electron scattering are similar. The comparison with the relativistic Fermi gas model (RFGM), which is widely used in data analyses of neutrino experiments, shows that the RFGM fails completely when applied to exclusive cross section data and leads to overestimated values of inclusive and total cross sections. We also found significant nuclear-model dependence of exclusive, inclusive and total cross sections for about 1 GeV energy. PACS numbers: 25.30.-c 25.30.Bf, 25.30.Pt, 13.15.+g I. INTRODUCTION The field of neutrino oscillations has been rapidly developing from the observation of anomalies in cosmic rays [1] and solar [2] neutrino data to the cross checks of these anomalies [3, 4] and most recently to terrestrial confirmations of neutrino oscillation hypothesis (Kamland, K2K [5] and MINOS [6]). The next steps in this field would be the precision measurements of observed mass splitting and mixing angles and detailed experimental study of the neutrino mixing matrix.
Physical Review C, 2008
Using recently derived relations between spin-dependent nuclear and nucleon g1 and g2 structure f... more Using recently derived relations between spin-dependent nuclear and nucleon g1 and g2 structure functions at finite Q2, we study nuclear effects in He3 in the nucleon resonance and deep inelastic regions. Comparing the finite-Q2 results with the standard convolution formulas obtained in the large-Q2 limit, we find significant broadening of the effective nucleon momentum distribution functions, leading to additional suppression of the nuclear g1 and g2 structure functions around the resonance peaks.
Physical Review C, 1995
ABSTRACT
Physical Review C, 2009
We propose a new method for extracting neutron structure functions from inclusive structure funct... more We propose a new method for extracting neutron structure functions from inclusive structure functions of nuclei, which employs an iterative procedure of solving integral convolution equations. Unlike earlier approaches, the new method is applicable to both spin-averaged and spin-...
Physical Review B, 2013
Using fermionic representation of spin degrees of freedom within the Popov-Fedotov approach we de... more Using fermionic representation of spin degrees of freedom within the Popov-Fedotov approach we develop an algorithm for Monte Carlo sampling of skeleton Feynman diagrams for Heisenberg type models. Our scheme works without modifications for any dimension of space, lattice geometry, and interaction range, i.e. it is suitable for dealing with frustrated magnetic systems at finite temperature. As a practical application we compute uniform magnetic susceptibility of the antiferromagnetic Heisenberg model on the triangular lattice and compare our results with the best available high-temperature expansions. We also report results for the momentum-dependence of the static magnetic susceptibility throughout the Brillouin zone.
Nuclear Physics B - Proceedings Supplements, 2007
... b Jefferson Lab, Newport News, Virginia 23606. ... Experimental data on the F 2 structure fun... more ... b Jefferson Lab, Newport News, Virginia 23606. ... Experimental data on the F 2 structure functions of the proton and deuteron, including recent results from CLAS at Jefferson Lab, have been used to construct their n less-than-or-equals, slant 12 moments. ...
Nuclear Physics A, 2006
We perform a global analysis of neutron F n 2 structure function data, obtained by combining prot... more We perform a global analysis of neutron F n 2 structure function data, obtained by combining proton and deuteron measurements over a large range of kinematics. From these data the lowest moments (n 10) of the leading twist neutron F n 2 structure function are extracted. Particular attention is paid to nuclear effects in the deuteron, which become increasingly important for the higher moments. Our results for the nonsinglet, isovector p-n combination of the leading twist moments are used to test recent lattice simulations. We also determine the lowest few moments of the higher twist contributions, and find these to be approximately isospin-independent, suggesting the possible dominance of ud correlations over uu and dd in the nucleon.
ABSTRACT We calculate magnetic susceptibility of the triangular-lattice quantum antiferromagnet i... more ABSTRACT We calculate magnetic susceptibility of the triangular-lattice quantum antiferromagnet in the correlated paramagnet regime and reveal surprising microscopic correspondence between quantum and classical models at all accessible temperatures T>0.375J. Namely, we observe a perfect match between the quantum static (zero Matsubara frequency) response χ(r), where r is the spatial coordinate, and its classical counterpart calculated at temperature Tcl(T). The correspondence curve is rather featureless and smoothly extrapolates to a finite value of Tcl= 0.28J when T/J ->0. If this extrapolation indeed holds true, then finite value of Tcl(0) implies that spins are not ordered in the ground state and form a spin liquid. Existing numerical evidence would not be in contradiction with the spin liquid state because the spin correlation length for the classical Heisenberg model at Tcl 0.28J is >1000 lattice periods and simulations dealing with small system sizes L< 10 would misidentify the ground state as ordered. Our results are based on the high-order skeleton Feynman diagrams within the fermionization framework.
AIP Conference Proceedings, 2007
We present a model for inclusive charged lepton-nucleon and (anti)neutrino-nucleon cross sections... more We present a model for inclusive charged lepton-nucleon and (anti)neutrino-nucleon cross sections at momentum transfer squared, Q2Q^2Q2, sim1rmGeV2\sim1 {\rm GeV}^2sim1rmGeV2. We quantify the impact of existing low-Q charged-lepton deep-inelastic scattering (DIS) data on effects due to high-twist operators and on the extraction of parton distribution functions (PDFs). No evidence is found for twist-6 contributions to structure functions (SF), and for
AIP Conference Proceedings, 2007
We discuss calculation of nuclear corrections to the structure functions for the deep-inelastic s... more We discuss calculation of nuclear corrections to the structure functions for the deep-inelastic scattering of muon and (anti)neutrino. Our approach includes a QCD description of the nucleon structure functions as well as the treatment of Fermi motion and nuclear binding, off-shell correction to bound nucleon structure functions, nuclear pion excess and nuclear shadowing. We emphasize the dependence of nuclear effects
We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-l... more We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-lepton and neutrino DIS data down to Q = 1 GeV. We also consider the data on neutrino-nucleon dimuon production, that allows us to disentangle the strange sea distribution. The fit results in \chi^2/NDP = 5150/4338 = 1.2 that demonstrates a good consistency of the data sets used
Proceedings of the XVI International Workshop on Deep-Inelastic Scattering and Related Topics, 2008
We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-l... more We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-lepton and neutrino DIS data down to Q = 1 GeV. We also consider the data on neutrino-nucleon dimuon production, that allows us to disentangle the strange sea distribution. The fit results in \chi^2/NDP = 5150/4338 = 1.2 that demonstrates a good consistency of the data sets used
15th International Workshop on Deep-Inelastic Scattering and Related Subjects DIS 2007, 2007
We check impact of the existing deep-inelastic scattering (DIS) data at low momentum transfer Q o... more We check impact of the existing deep-inelastic scattering (DIS) data at low momentum transfer Q on the global QCD t of parton distribution functions (PDFs). We nd that DIS data are described well within the NNLO QCD approximation with the target mass and phenomenological high-twist corrections down to Q 1 GeV. The twist-4 terms in the DIS structure functions are
Physical Review Letters, 1985
We study the European Muon Collaboration effect within the conventional nuclear theory using the ... more We study the European Muon Collaboration effect within the conventional nuclear theory using the free-nucleon structure function. It is shown that qualitative agreement with the experiment can be obtained by taking into account the momentum (Fermi motion) and the energy distributions of nucleons in nuclei.
Physical Review Letters, 1986
Physical Review D, 2004
W e present resul ts ofa perturbati ve Q C D anal ysi s ofdeep i nel asti c m easurem ents ofboth... more W e present resul ts ofa perturbati ve Q C D anal ysi s ofdeep i nel asti c m easurem ents ofboth the deuteron and proton structure functi ons. W e eval uate the theoreti cal uncertai nty associ ated to nucl ear e ects i n the deuteron, and we extract si m ul taneousl y the i sospi n depedendence of: i) the hi gher tw i sts term s;ii) the rati o ofthe l ongi tudi nalto transverse cross secti ons,R = L = T ; iii) the rati o ofthe neutron to proton structure functi ons,F n 2 =F p 2 . T he extracti on of the l atter, i n parti cul ar, has been at the center of an i ntense debate. Its accurate determ i nati on i s cruci al both theoreti cal l y and for the i nterpretati on of the m ore preci se neutri no experi m ents i ncl udi ng the new l y pl anned hi gh i ntensi ty 50 G eV proton synchrotron.
Physical Review C, 1994
We present a unified description of nuclear deep inelastic scattering (DIS) over the whole region... more We present a unified description of nuclear deep inelastic scattering (DIS) over the whole region 0 < x < 1 of the Bjorken variable. Our approach is based on a relativistically covariant formalism which uses analytical properties of quark correlators. In the laboratory frame it naturally incorporates two mechanisms of DIS: (I) scattering from quarks and antiquarks in the target and (II) production of quark-antiquark pairs followed by interactions with the target. We first calculate structure functions of the free nucleon and develop a model for the quark spectral functions. We show that mechanism (II) is responsible for the sea quark content of the nucleon while mechanism (I) governs the valence part of the nucleon structure functions. We find that the coherent interaction ofqq pairs with nucleons in the nucleus leads to shadowing at small x and discuss this effect in detail. In the large x region DIS takes place mainly on a single nucleon. There we focus on the derivation of the convolution model. We point out that the off-shell properties of the bound nucleon structure function give rise to sizable nuclear effects.
Physical Review C, 2007
The charged-current quasi-elastic scattering of muon neutrinos on oxygen target is computed for n... more The charged-current quasi-elastic scattering of muon neutrinos on oxygen target is computed for neutrino energies between 200 MeV and 2.5 GeV using the relativistic distortedwave impulse approximation with relativistic optical potential, which was earlier successfully applied to describe electron-nucleus data. We study both neutrino and electron processes and show that the reduced exclusive cross sections for neutrino and electron scattering are similar. The comparison with the relativistic Fermi gas model (RFGM), which is widely used in data analyses of neutrino experiments, shows that the RFGM fails completely when applied to exclusive cross section data and leads to overestimated values of inclusive and total cross sections. We also found significant nuclear-model dependence of exclusive, inclusive and total cross sections for about 1 GeV energy. PACS numbers: 25.30.-c 25.30.Bf, 25.30.Pt, 13.15.+g I. INTRODUCTION The field of neutrino oscillations has been rapidly developing from the observation of anomalies in cosmic rays [1] and solar [2] neutrino data to the cross checks of these anomalies [3, 4] and most recently to terrestrial confirmations of neutrino oscillation hypothesis (Kamland, K2K [5] and MINOS [6]). The next steps in this field would be the precision measurements of observed mass splitting and mixing angles and detailed experimental study of the neutrino mixing matrix.
Physical Review C, 2008
Using recently derived relations between spin-dependent nuclear and nucleon g1 and g2 structure f... more Using recently derived relations between spin-dependent nuclear and nucleon g1 and g2 structure functions at finite Q2, we study nuclear effects in He3 in the nucleon resonance and deep inelastic regions. Comparing the finite-Q2 results with the standard convolution formulas obtained in the large-Q2 limit, we find significant broadening of the effective nucleon momentum distribution functions, leading to additional suppression of the nuclear g1 and g2 structure functions around the resonance peaks.
Physical Review C, 1995
ABSTRACT
Physical Review C, 2009
We propose a new method for extracting neutron structure functions from inclusive structure funct... more We propose a new method for extracting neutron structure functions from inclusive structure functions of nuclei, which employs an iterative procedure of solving integral convolution equations. Unlike earlier approaches, the new method is applicable to both spin-averaged and spin-...
Physical Review B, 2013
Using fermionic representation of spin degrees of freedom within the Popov-Fedotov approach we de... more Using fermionic representation of spin degrees of freedom within the Popov-Fedotov approach we develop an algorithm for Monte Carlo sampling of skeleton Feynman diagrams for Heisenberg type models. Our scheme works without modifications for any dimension of space, lattice geometry, and interaction range, i.e. it is suitable for dealing with frustrated magnetic systems at finite temperature. As a practical application we compute uniform magnetic susceptibility of the antiferromagnetic Heisenberg model on the triangular lattice and compare our results with the best available high-temperature expansions. We also report results for the momentum-dependence of the static magnetic susceptibility throughout the Brillouin zone.
Nuclear Physics B - Proceedings Supplements, 2007
... b Jefferson Lab, Newport News, Virginia 23606. ... Experimental data on the F 2 structure fun... more ... b Jefferson Lab, Newport News, Virginia 23606. ... Experimental data on the F 2 structure functions of the proton and deuteron, including recent results from CLAS at Jefferson Lab, have been used to construct their n less-than-or-equals, slant 12 moments. ...
Nuclear Physics A, 2006
We perform a global analysis of neutron F n 2 structure function data, obtained by combining prot... more We perform a global analysis of neutron F n 2 structure function data, obtained by combining proton and deuteron measurements over a large range of kinematics. From these data the lowest moments (n 10) of the leading twist neutron F n 2 structure function are extracted. Particular attention is paid to nuclear effects in the deuteron, which become increasingly important for the higher moments. Our results for the nonsinglet, isovector p-n combination of the leading twist moments are used to test recent lattice simulations. We also determine the lowest few moments of the higher twist contributions, and find these to be approximately isospin-independent, suggesting the possible dominance of ud correlations over uu and dd in the nucleon.
ABSTRACT We calculate magnetic susceptibility of the triangular-lattice quantum antiferromagnet i... more ABSTRACT We calculate magnetic susceptibility of the triangular-lattice quantum antiferromagnet in the correlated paramagnet regime and reveal surprising microscopic correspondence between quantum and classical models at all accessible temperatures T>0.375J. Namely, we observe a perfect match between the quantum static (zero Matsubara frequency) response χ(r), where r is the spatial coordinate, and its classical counterpart calculated at temperature Tcl(T). The correspondence curve is rather featureless and smoothly extrapolates to a finite value of Tcl= 0.28J when T/J ->0. If this extrapolation indeed holds true, then finite value of Tcl(0) implies that spins are not ordered in the ground state and form a spin liquid. Existing numerical evidence would not be in contradiction with the spin liquid state because the spin correlation length for the classical Heisenberg model at Tcl 0.28J is >1000 lattice periods and simulations dealing with small system sizes L< 10 would misidentify the ground state as ordered. Our results are based on the high-order skeleton Feynman diagrams within the fermionization framework.
AIP Conference Proceedings, 2007
We present a model for inclusive charged lepton-nucleon and (anti)neutrino-nucleon cross sections... more We present a model for inclusive charged lepton-nucleon and (anti)neutrino-nucleon cross sections at momentum transfer squared, Q2Q^2Q2, sim1rmGeV2\sim1 {\rm GeV}^2sim1rmGeV2. We quantify the impact of existing low-Q charged-lepton deep-inelastic scattering (DIS) data on effects due to high-twist operators and on the extraction of parton distribution functions (PDFs). No evidence is found for twist-6 contributions to structure functions (SF), and for
AIP Conference Proceedings, 2007
We discuss calculation of nuclear corrections to the structure functions for the deep-inelastic s... more We discuss calculation of nuclear corrections to the structure functions for the deep-inelastic scattering of muon and (anti)neutrino. Our approach includes a QCD description of the nucleon structure functions as well as the treatment of Fermi motion and nuclear binding, off-shell correction to bound nucleon structure functions, nuclear pion excess and nuclear shadowing. We emphasize the dependence of nuclear effects
We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-l... more We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-lepton and neutrino DIS data down to Q = 1 GeV. We also consider the data on neutrino-nucleon dimuon production, that allows us to disentangle the strange sea distribution. The fit results in \chi^2/NDP = 5150/4338 = 1.2 that demonstrates a good consistency of the data sets used
Proceedings of the XVI International Workshop on Deep-Inelastic Scattering and Related Topics, 2008
We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-l... more We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-lepton and neutrino DIS data down to Q = 1 GeV. We also consider the data on neutrino-nucleon dimuon production, that allows us to disentangle the strange sea distribution. The fit results in \chi^2/NDP = 5150/4338 = 1.2 that demonstrates a good consistency of the data sets used
15th International Workshop on Deep-Inelastic Scattering and Related Subjects DIS 2007, 2007
We check impact of the existing deep-inelastic scattering (DIS) data at low momentum transfer Q o... more We check impact of the existing deep-inelastic scattering (DIS) data at low momentum transfer Q on the global QCD t of parton distribution functions (PDFs). We nd that DIS data are described well within the NNLO QCD approximation with the target mass and phenomenological high-twist corrections down to Q 1 GeV. The twist-4 terms in the DIS structure functions are