Kruglov, N.A.
Deep Inelastic Scattering
Max results
Sort by Reverse order

Showing 10 of 91 results

Precision measurements of $g_1$ of the proton and the deuteron with 6 GeV electrons

The CLAS collaboration Prok, Y. ; Bosted, P. ; Kvaltine, N. ; et al.
Phys.Rev.C 90 (2014) 025212, 2014.
Inspire Record 1292133 DOI 10.17182/hepdata.64411

The inclusive polarized structure functions of the proton and deuteron, g1p and g1d, were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at lab angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual DIS kinematics, Q^2>1 GeV^2 and the final-state invariant mass W>2 GeV, the ratio of polarized to unpolarized structure functions g1/F1 is found to be nearly independent of Q^2 at fixed x. Significant resonant structure is apparent at values of W up to 2.3 GeV. In the framework of perturbative QCD, the high-W results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions.

0 data tables

Collins and Sivers asymmetries for pions and kaons in muon-deuteron DIS

The COMPASS collaboration Alekseev, M. ; Alexakhin, V.Yu. ; Alexandrov, Yu. ; et al.
Phys.Lett.B 673 (2009) 127-135, 2009.
Inspire Record 779473 DOI 10.17182/hepdata.48532

The measurements of the Collins and Sivers asymmetries of identified hadrons produced in deep-inelastic scattering of 160 GeV/c muons on a transversely polarised 6LiD target at COMPASS are presented. The results for charged pions and charged and neutral kaons correspond to all data available, which were collected from 2002 to 2004. For all final state particles both the Collins and Sivers asymmetries turn out to be small, compatible with zero within the statistical errors, in line with the previously published results for not identified charged hadrons, and with the expected cancellation between the u- and d-quark contributions.

17 data tables
Table 2

The Collins and Sivers asymmetry as a function of PT for 'ALL' positive pions from the 2003-2004 data.. Errors are statistical only.

Table 3

The Collins and Sivers asymmetry as a function of Z for 'ALL' positive pions from the 2003-2004 data.. Errors are statistical only.

Table 5

The Collins and Sivers asymmetry as a function of PT for 'ALL' negative pions from the 2003-2004 data.. Errors are statistical only.

More…

Measurement of the Cross Section for open b-Quark Production in Two-Photon Interactions at LEP

The ALEPH collaboration Schael, S. ; Barate, R. ; Bruneliere, R. ; et al.
JHEP 09 (2007) 102, 2007.
Inspire Record 753710 DOI 10.17182/hepdata.48802

Inclusive beauty-quark production in two-photon collisions has been measured at LEP using an integrated luminosity of 698 pb-1 collected by the ALEPH detector with sqrt(s) between 130 and 209 GeV. The b quarks were identified using lifetime information. The cross section is found to be sigma(e+ e- --> e+ e- b \bar{b} X) = (5.4 +/- 0.8 (stat) +/- 0.8 (syst)) pb which is consistent with Next-to-Leading Order QCD.

1 data table
Table 1

Cross section for the process E+ E- --> E+ E- BQUARK BQUARKBAR X.


Spin asymmetry A(1)(d) and the spin-dependent structure function g1(d) of the deuteron at low values of x and Q**2.

The Compass collaboration Ageev, E.S. ; Alexakhin, V.Yu. ; Alexandrov, Yu. ; et al.
Phys.Lett.B 647 (2007) 330-340, 2007.
Inspire Record 742118 DOI 10.17182/hepdata.48534

We present a precise measurement of the deuteron longitudinal spin asymmetry A_1^d and of the deuteron spin-dependent structure function g_1^d at Q^2 < 1 GeV^2 and 4*10^-5 < x < 2.5*10^-2 based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A_1^d and g_1^d are found to be consistent with zero in the whole range of x.

1 data table
Table 1

Measured values of A1 and G1 at mean values of X, Q**2 and Y.


Separated structure functions for the exclusive electroproduction of K+ Lambda and K+ Sigma0 final states.

The CLAS collaboration Ambrozewicz, P. ; Carman, D.S. ; Feuerbach, R.J. ; et al.
Phys.Rev.C 75 (2007) 045203, 2007.
Inspire Record 732363 DOI 10.17182/hepdata.4994

We report measurements of the exclusive electroproduction of $K^+\Lambda$ and $K^+\Sigma^0$ final states from a proton target using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The separated structure functions $\sigma_T$, $\sigma_L$, $\sigma_{TT}$, and $\sigma_{LT}$ were extracted from the $\Phi$- and $\epsilon$-dependent differential cross sections taken with electron beam energies of 2.567, 4.056, and 4.247 GeV. This analysis represents the first $\sigma_L/\sigma_T$ separation with the CLAS detector, and the first measurement of the kaon electroproduction structure functions away from parallel kinematics. The data span a broad range of momentum transfers from $0.5\leq Q^2\leq 2.8$ GeV$^2$ and invariant energy from $1.6\leq W\leq 2.4$ GeV, while spanning nearly the full center-of-mass angular range of the kaon. The separated structure functions reveal clear differences between the production dynamics for the $\Lambda$ and $\Sigma^0$ hyperons. These results provide an unprecedented data sample with which to constrain current and future models for the associated production of strangeness, which will allow for a better understanding of the underlying resonant and non-resonant contributions to hyperon production.

531 data tables
Table 1

Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.6 to 1.7 GeV.

Table 2

Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.70 to 1.75 GeV.

Table 3

Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.75 to 1.80 GeV.

More…

The Deuteron Spin-dependent Structure Function g1d and its First Moment

The COMPASS collaboration Alexakhin, V.Yu. ; Alexandrov, Yu. ; Alexeev, G.D. ; et al.
Phys.Lett.B 647 (2007) 8-17, 2007.
Inspire Record 726688 DOI 10.17182/hepdata.48555

We present a measurement of the deuteron spin-dependent structure function g1d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the first moment of g1d(x), and for the matrix element of the singlet axial current, a0. The results of QCD fits in the next to leading order (NLO) on all g1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function Delta G positive or negative, which describe the data equally well. In both cases, at Q^2 = 3 (GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3 in absolute value.

1 data table
Table 1

Measured values of A1 and G1 at mean values of X, Q**2.. For the first two data points the minimum Q**2 cut was reduced from 1 to 0.7 GeV**2.


A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target

The COMPASS collaboration Ageev, E.S. ; Alexakhin, V.Yu. ; Alexandrov, Yu. ; et al.
Nucl.Phys.B 765 (2007) 31-70, 2007.
Inspire Record 729695 DOI 10.17182/hepdata.48535

New high precision measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised 6LiD target are presented. The data were taken in 2003 and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. Both the Collins and Sivers asymmetries turn out to be compatible with zero, within the present statistical errors, which are more than a factor of 2 smaller than those of the published COMPASS results from the 2002 data. The final results from the 2002, 2003 and 2004 runs are compared with naive expectations and with existing model calculations.

24 data tables
Table 1

Collins asymmetry against PT for all negative hadrons.

Table 2

Collins asymmetry against Bjorken X for all negative hadrons.

Table 3

Collins asymmetry against Z for all negative hadrons.

More…

Measurement of the $x$- and $Q^2$-Dependence of the Asymmetry $A_1$ on the Nucleon

The CLAS collaboration Dharmawardane, K.V. ; Kuhn, S.E. ; Bosted, Peter E. ; et al.
Phys.Lett.B 641 (2006) 11-17, 2006.
Inspire Record 717523 DOI 10.17182/hepdata.6726

We report results for the virtual photon asymmetry $A_1$ on the nucleon from new Jefferson Lab measurements. The experiment, which used the CEBAF Large Acceptance Spectrometer and longitudinally polarized proton ($^{15}$NH$_3$) and deuteron ($^{15}$ND$_3$) targets, collected data with a longitudinally polarized electron beam at energies between 1.6 GeV and 5.7 GeV. In the present paper, we concentrate on our results for $A_1(x,Q^2)$ and the related ratio $g_1/F_1(x,Q^2)$ in the resonance and the deep inelastic regions for our lowest and highest beam energies, covering a range in momentum transfer $Q^2$ from 0.05 to 5.0 GeV$^2$ and in final-state invariant mass $W$ up to about 3 GeV. Our data show detailed structure in the resonance region, which leads to a strong $Q^2$--dependence of $A_1(x,Q^2)$ for $W$ below 2 GeV. At higher $W$, a smooth approach to the scaling limit, established by earlier experiments, can be seen, but $A_1(x,Q^2)$ is not strictly $Q^2$--independent. We add significantly to the world data set at high $x$, up to $x = 0.6$. Our data exceed the SU(6)-symmetric quark model expectation for both the proton and the deuteron while being consistent with a negative $d$-quark polarization up to our highest $x$. This data setshould improve next-to-leading order (NLO) pQCD fits of the parton polarization distributions.

306 data tables
Table 1

A1 and g1/F1 for the P target at incident energy 1.6000 GeV and W = 1.1300 GeV.

Table 2

A1 and g1/F1 for the P target at incident energy 1.6000 GeV and W = 1.1500 GeV.

Table 3

A1 and g1/F1 for the P target at incident energy 1.6000 GeV and W = 1.1700 GeV.

More…

Measurement of the deuteron structure function F2 in the resonance region and evaluation of its moments.

The CLAS collaboration Osipenko, M. ; Ricco, G. ; Simula, S. ; et al.
Phys.Rev.C 73 (2006) 045205, 2006.
Inspire Record 684005 DOI 10.17182/hepdata.12254

Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function F2 with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasi-elastic peak up to the invariant mass of the final-state hadronic system W~2.7 GeV with four-momentum transfers Q2 from 0.4 to 6 (GeV/c)^2. These data are complementary to previous measurements of the proton structure function F2 and cover a similar two-dimensional region of Q2 and Bjorken variable x. Determination of the deuteron F2 over a large x interval including the quasi-elastic peak as a function of Q2, together with the other world data, permit a direct evaluation of the structure function moments for the first time. By fitting the Q2 evolution of these moments with an OPE-based twist expansion we have obtained a separation of the leading twist and higher twist terms. The observed Q2 behaviour of the higher twist contribution suggests a partial cancellation of different higher twists entering into the expansion with opposite signs. This cancellation, found also in the proton moments, is a manifestation of the duality phenomenon in the F2 structure function.

113 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

More…

First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering.

The COMPASS collaboration Alexakhin, V.Yu. ; Alexandrov, Yu. ; Alexeev, G.D. ; et al.
Phys.Rev.Lett. 94 (2005) 202002, 2005.
Inspire Record 677550 DOI 10.17182/hepdata.48553

First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6-LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.

6 data tables
Table 1

Asymmetries as a function of X for LEADING hadrons.

Table 2

Asymmetries as a function of Z for LEADING hadrons.

Table 3

Asymmetries as a function of PT for LEADING hadrons.

More…