共查询到20条相似文献,搜索用时 31 毫秒
1.
A.V. Kotikov A.V. Lipatov G. Parente N.P. Zotov 《The European Physical Journal C - Particles and Fields》2002,26(1):51-66
We calculate the perturbative parts of the structure functions F
2
c
and for a gluon target having non-zero transverse momentum squared at order . The results of the double convolution (with respect to the Bjorken variable and the transverse momentum) of the perturbative part and the unintegrated gluon densities are compared with the HERA experimental
data for F
2
c
. The contribution from the structure function ranges in 10-30% of that of F
2
c
at the kinematical range of the HERA experiments.
Received: 18 April 2002 / Revised version: 24 July 2002 / Published online: 7 October 2002
RID="a"
ID="a" e-mail: kotikov@sunse.jinr.ru
RID="b"
ID="b" e-mail: gonzalo@fpaxp1.usc.es 相似文献
2.
G. R. Boroun 《Journal of Experimental and Theoretical Physics》2010,111(4):567-569
We study the accuracy of the Regge behavior of the gluon distribution function for an approximate relation that is frequently
used to extract the logarithmic slopes of the structure function from the gluon distribution at small x. We show that the Regge behavior analysis results are comparable with HERA data and are also better than other methods that
expand the gluon density at distinct points of expansion. We also show that for Q
2 = 22.4 GeV2, the x dependence of the data is well described by gluon shadowing corrections to the GLR-MQ equation. The resulting analytic expression
allows us to predict the logarithmic derivative ∂F
2(x, Q
2)/∂lnQ
2 and to compare the results with the H1 data and a QCD analysis fit with the MRST parameterization input. 相似文献
3.
A. V. Kotikov A. V. Lipatov N. P. Zotov 《Journal of Experimental and Theoretical Physics》2005,101(5):811-816
We use the results for the structure function FL for a gluon target with a nonzero transverse momentum squared at the order αs, obtained in our previous paper, for comparison with recent H1 experimental data for FL at fixed W values and with collinear GRV predictions in the leading-order and next-to-leading-order approximations. 相似文献
4.
Andrea Bressan 《Foundations of Physics》2010,40(7):1030-1041
The COMPASS experiment at CERN is carrying on an experimental investigation of the spin structure of the nucleon, covering
both longitudinal and transverse spin phenomena. In the first case, the central topic is the direct measurement of the gluon
polarisation with the hope to solve the spin crisis first observed by EMC. The result shows that Δg/g is small around x
g
≃0.1, and its first moment should not be larger than 0.2—0.3 in absolute value. About transverse spin effects, evidence is
given for new phenomena, associated with transverse momentum dependent distribution and fragmentation functions. 相似文献
5.
We demonstrate that all the known single- and double-logarithm summations for a parton distribution function can be unified
in the Collins–Soper resummation technique by applying soft approximations appropriate in different kinematic regions to real
gluon emissions. Neglecting the gluon longitudinal momentum, we obtain the (double-logarithm) resummation for two-scale QCD processes, and the Balitsky–Fadin–Kuraev–Lipatov (single-logarithm) equation
for one-scale processes. Neglecting the transverse momentum, we obtain the threshold (double-logarithm) resummation for two-scale
processes, and the Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (single-logarithm) equation for one-scale processes. If we keep
the longitudinal and transverse momenta simultaneously, we derive a unified resummation for a large Bjorken variable x, and a unified evolution equation appropriate for both intermediate and small x.
Received: 9 March 1999 / Revised version: 12 April 1999 / Published online: 3 August 1999 相似文献
6.
We calculate the impact factor coupling a virtual photon to a gluon via a massive quark–antiquark pair at LL order, but with the imposition of the correct gluon kinematics. Exact analytical results are presented in triple Mellin space with respect to scaled Bjorken x, gluon transverse momentum and heavy quark mass. The application of these results to the calculation of approximate NLL coefficient functions needed to relate structure functions to the BFKL gluon is presented. The NLL effects with running coupling are seen to lead to a suppression of the small x divergence when compared with the fixed and running coupling LL results, but less than in the massless case. 相似文献
7.
G. T. Jones B. W. Kennedy R. P. Middleton S. W. O'Neale A. M. Cooper A. Grant H. Klein J. Mittendorfer D. R. O. Morrison A. Parker P. Schmid H. Wachsmuth F. Hamisi M. M. Mobayyen O. Villalobos-Baillie M. Aderholz L. Deck N. Schmitz W. Wittek G. Corrigan G. Myatt D. Radojicic M. Retter 《Zeitschrift fur Physik C Particles and Fields》1984,25(2):121-127
Data from a neutrino and antineutrino hydrogen experiment with BEBC are used to investigate transverse properties of the produced charged hadrons. Measurements are presented on average transverse momenta of charged pions as functions of Feynman-x and the hadronic mass, on the transverse momentum flow within an event and on jet-related quantities. The main features of the data are well described by the LUND model. The data favour a version of the model in which soft gluon effects are included and the primordial transverse momentum of the quarks in the proton is small. Effects from 1st order QCD (hard gluon emission) are negligible. 相似文献
8.
9.
Unintegrated gluon densities in nuclei, dipole-nucleus cross-sections and quark densities are numerically investigated in
the high-color limit, with the scattering on a heavy nucleus exactly described by the sum of fan diagrams of BFKL pomerons.
The initial condition for the evolution in rapidity is quickly forgotten, and the gluon density presents a “supersaturation”
pattern, as previous studies indicated. Both dipole-nucleus cross-sections and quark densities present the expected saturation
features. Identifying the position in transverse momentum l of the maximum of the gluon distribution with the saturation momentum , at large rapidities all distributions depend on only one variable, or .
Received: 4 April 2001 / Revised version: 24 April 2001 / Published online: 8 June 2001 相似文献
10.
Experiment E97-006 was performed at JLab in Hall C to measure the spectral function S(Em, Pm) via (e,e'p) for the nuclei C, Al, Fe, Au in the region of high missing energy Em and missing momentum Pm. To study short-range correlations as well as the reaction mechanism beyond PWIA data were taken in parallel and perpendicular kinematics covering a Pm range of up to 800 MeV/c. Assuming PWIA the spectral function can be extracted from the data. Preliminary results of the spectral function are compared to the Correlated Basis Function theory of Benhar and the Green's function approach of Müther et al.. The spectral functions obtained for different targets are compared as well.Received: 1 November 2002, Published online: 15 July 2003PACS:
21.10.-k Properties of nuclei; nuclear energy levels - 25.30.-c Lepton-induced reactionsD. Rohe: For the E97-006 Collaboration 相似文献
11.
G. J. Kunde H. van Hecke K. Hessler C. Mironov 《The European Physical Journal C - Particles and Fields》2009,61(4):785-788
The Large Hadron Collider will allow studies of hard probes in nucleus-nucleus collisions which were not accessible at the
Relativistic Heavy Ion Collider—even the study of small cross-section Z
0-tagged jets becomes possible. Going beyond the measurement of back-to-back correlations of two strongly interacting particles
to measure plasma properties, we replace one side by an electromagnetic probe which propagates through the plasma undisturbed
and therefore provides a measurement of the energy of the initial hard scattering. We show that at sufficiently high transverse
momentum the Z
0-tagged jets originate predominately from the fragmentation of quarks and anti-quarks while gluon jets are suppressed. We
propose to use lepton-pair tagged jets to study medium-induced partonic energy loss and to measure in-medium parton fragmentation
functions to determine the opacity of the quark gluon plasma. 相似文献
12.
D. d'Enterria 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):816-823
We present a summary of the physics of gluon saturation and non-linear QCD evolution at small values of the parton momentum
fraction x in the proton and nucleus in the context of recent experimental results at HERA and RHIC. The rich physics potential of low-x studies at the LHC, especially in the forward region, is discussed and some benchmark measurements in pp, pA and AA collisions are introduced. 相似文献
13.
14.
Jyotsna Galgale Nupinder Kaur Preeti Singh Manik Manake N. K. Gaur R. K. Singh 《Pramana》2004,63(2):413-417
An extended three-body force shell model (ETSM) has been applied to investigate the static and dynamic properties of KCN
x
Cl1−x
for the compositionx = 0.56 and 1.0 at 300 K. The phonon dispersion curves computed by us are compared with the single crystal neutron diffraction
data. The unusual features of these curves are the upward curvature seen in some of the acoustic branches. This is a result
ofK-dependent softening of the phonon due to translation-rotation coupling. The transverse acoustic branch is more soft near
the zone centre. 相似文献
15.
16.
T. Sjöstrand O. Smirnova Ch. Zacharatou Jarlskog 《The European Physical Journal C - Particles and Fields》2001,21(1):93-98
In the hadronic decays of , gluon emission leads to the appearance of the longitudinal component of the fragmentation function, . Measurement of and the transverse component, , could thus provide insight into the gluon fragmentation function. However, hadronization corrections at low x can be significant. Here we present a method of accounting for such corrections, using the Jetset event generator as illustration.
Received: 11 April 2001 / Revised version: 4 May 2001 / Published online: 29 June 2001 相似文献
17.
The EXCHARM Collaboration A.N. Aleev et al. 《The European Physical Journal C - Particles and Fields》2003,27(4):547-553
The inclusive production cross-sections of , , and in neutron-carbon interactions at GeV mean energy of neutrons have been measured. The parameters n and b of differential cross-section parametrisation , where xF is the Feynman variable, pt is the transverse momentum, have been obtained. The kinematic region of validity of the parametrisation has been defined.
Results are compared with published experimental data.
Received: 7 June 2002 / Revised version: 23 January 2003 / Published online: 3 March 2003 相似文献
18.
M. Samsel-Czekała G. Kontrym-Sznajd G. Döring W. Schülke J. Kwiatkowska F. Maniawski S. Kaprzyk A. Bansil 《Applied Physics A: Materials Science & Processing》2003,77(1):87-92
A reconstruction technique based on the solution of the Radon transform in terms of Jacobi polynomials is used to obtain the
3D electron momentum density, ϱ(p), from nine high-resolution Compton profiles (CPs) for a Cu0.9Al0.1 disordered alloy single crystal. The method was also applied to theoretical CPs computed within the Korringa–Kohn–Rostoker
coherent potential approximation (KKR-CPA) first-principles scheme for the same nine orientations of the crystal. The experimental
ϱ(p) is in satisfactory agreement with the theoretical ϱ(p), shows most details of the Fermi surface (FS) and exhibits electron correlation effects. We comment on the map of the FS
obtained by folding the reconstructed ϱ(p) into the first Brillouin zone, which yields the occupation number density, ϱ(k). A test of the validity of data via a consistency condition (within our reconstruction algorithm) as well as the propagation
of experimental noise in the reconstruction of both ϱ(p) and ϱ(k) are investigated.
Received: 24 October 2001 / Accepted: 20 January 2002 / Published online: 3 June 2002
RID="*"
ID="*"Corresponding author. Fax: +48-71/344-10-29, E-mail: samsel@int.pan.wroc.pl 相似文献
19.
G.W. Meng X.S. Peng Y.W. Wang C.Z. Wang X.F. Wang L.D. Zhang 《Applied Physics A: Materials Science & Processing》2003,76(1):119-121
Aligned SiOx nanowire arrays standing on a Si substrate were successfully synthesized using a simple method by heating a single-crystalline
Si slice covered with SiO2 nanoparticles at 1000 °C in a flowing Ar atmosphere. The SiOx nanowire arrays were characterized by scanning electron microscopy and transmission electron microscopy. The SiOx nanowires become progressively thinner from bottom to top. The formation process of the SiOx nanowire arrays is closely related to a vapor–solid mechanism. Room-temperature photoluminescence measurements under excitation
at 260 nm showed that the SiOx nanowire arrays had a strong blue–green emission at 500 nm (about 2.5 eV), which may be related to oxygen defects.
Received: 29 April 2002 / Accepted: 30 April 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +86-551-559-1434, E-mail: gwmeng@mail.issp.ac.cn 相似文献
20.
Inclusive cross sections for Higgs boson production in proton-proton collisions are calculated in the formalism of unintegrated
gluon distributions (UGDFs). Different UGDFs from the literature are used. Although they were constructed in order to describe
the HERA deep-inelastic scattering F2 data, they lead to surprisingly different results for Higgs boson production. We present both the two-dimensional invariant
cross section as a function of Higgs boson rapidity and transverse momentum, as well as the corresponding projections on rapidity
or transverse momentum. We quantify the differences between different UGDs by applying different cuts on interrelations between
the transverse momentum of the Higgs and the transverse momenta of both fusing gluons. We focus on the large rapidity region.
The interplay of the gluon-gluon fusion and weak-boson fusion in rapidity and transverse momentum is discussed. We find that
above pt ∼ 50–100 GeV the weak-gauge boson fusion dominates over gluon-gluon fusion.
PACS. 12.38.Bx,12.38.Cy,13.85.Qk,14.70.Hp,14.80.Bn 相似文献