scholarly journals The black disk to be observed in the Orear region

2012 ◽  
Vol 888 ◽  
pp. 1-6 ◽  
Author(s):  
I.M. Dremin
Keyword(s):  
Black Disk

scholarly journals Saturation effects in SIDIS at very forward rapidities

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
E. Iancu ◽  
A. H. Mueller ◽  
D. N. Triantafyllopoulos ◽  
S. Y. Wei
Keyword(s):  
Inelastic Scattering ◽  
Cross Section ◽  
Cross Sections ◽  
Virtual Photon ◽  
Large Fraction ◽  
Quark Distribution ◽  
High Energy ◽  
Longitudinal Momentum ◽  
Black Disk ◽  
Gluon Saturation

Abstract Using the dipole picture for electron-nucleus deep inelastic scattering at small Bjorken x, we study the effects of gluon saturation in the nuclear target on the cross-section for SIDIS (single inclusive hadron, or jet, production). We argue that the sensitivity of this process to gluon saturation can be enhanced by tagging on a hadron (or jet) which carries a large fraction z ≃ 1 of the longitudinal momentum of the virtual photon. This opens the possibility to study gluon saturation in relatively hard processes, where the virtuality Q2 is (much) larger than the target saturation momentum $$ {Q}_s^2 $$ Q s 2 , but such that z(1 − z)Q2 ≲ $$ {Q}_s^2 $$ Q s 2 . Working in the limit z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we predict new phenomena which would signal saturation in the SIDIS cross-section. For sufficiently low transverse momenta k⊥ ≪ Qs of the produced particle, the dominant contribution comes from elastic scattering in the black disk limit, which exposes the unintegrated quark distribution in the virtual photon. For larger momenta k⊥ ≳ Qs, inelastic collisions take the leading role. They explore gluon saturation via multiple scattering, leading to a Gaussian distribution in k⊥ centred around Qs. When z(1 − z)Q2 ≪ Q2, this results in a Cronin peak in the nuclear modification factor (the RpA ratio) at moderate values of x. With decreasing x, this peak is washed out by the high-energy evolution and replaced by nuclear suppression (RpA< 1) up to large momenta k⊥ ≫ Qs. Still for z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we also compute SIDIS cross-sections integrated over k⊥. We find that both elastic and inelastic scattering are controlled by the black disk limit, so they yield similar contributions, of zeroth order in the QCD coupling.

scholarly journals TACHYON DYNAMICS OF THE BLACK DISC LIMIT IN THE HARD SMALL x PROCESSES IN QCD

2006 ◽  
Vol 21 (07) ◽  
pp. 549-558 ◽  
Author(s):  
B. BLOK ◽  
L. FRANKFURT
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
High Energy ◽  
Black Disk ◽  
Black Disc ◽  
Energy Behavior ◽  
Small X ◽  
The Cross ◽  
The Impact ◽  
Black Disc Limit

We investigate the effective field theory (EFT) which gives the approximate description of the scattering of two hard small dipoles in the small x processes in QCD near the black disc limit (BDL). We argue that the perturbative QCD approaches predict the existence of tachyon and visualize it in the approximation where α′P=0. We demonstrate that the high energy behavior of the cross-section depends strongly on the diffusion law in the impact parameter plane. On the other hand, almost threshold behavior of the cross section of the hard processes and multiplicities, i.e. fast increase of cross sections (color inflation), melting of ladders into color network and softening of the longitudinal distributions of hadrons are qualitatively insensitive to the value of diffusion in the impact parameter space. We evaluate α′P near the black disk limit and find significant α′P as the consequence of the probability conservation.

Unitarity, (anti)shadowing, and black-disk limit

2000 ◽  
Vol 63 (5) ◽  
pp. 891-896 ◽  
Author(s):  
P. Desgrolard ◽  
L. Jenkovszky ◽  
B. V. Struminsky
Keyword(s):  
Black Disk

Parallel Advantage: Further Evidence for Bottom-up Saliency Computation by Human Primary Visual Cortex

Perception ◽  
2022 ◽  
Vol 51 (1) ◽  
pp. 60-69
Author(s):  
Li Zhaoping
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Surround Suppression ◽  
Bottom Up ◽  
Black Disk ◽  
V1 Neurons ◽  
Behavioral Observations ◽  
White Disk ◽  
Special Case

Finding a target among uniformly oriented non-targets is typically faster when this target is perpendicular, rather than parallel, to the non-targets. The V1 Saliency Hypothesis (V1SH), that neurons in the primary visual cortex (V1) signal saliency for exogenous attentional attraction, predicts exactly the opposite in a special case: each target or non-target comprises two equally sized disks displaced from each other by 1.2 disk diameters center-to-center along a line defining its orientation. A target has two white or two black disks. Each non-target has one white disk and one black disk, and thus, unlike the target, activates V1 neurons less when its orientation is parallel rather than perpendicular to the neurons’ preferred orientations. When the target is parallel, rather than perpendicular, to the uniformly oriented non-targets, the target’s evoked V1 response escapes V1’s iso-orientation surround suppression, making the target more salient. I present behavioral observations confirming this prediction.

Visual Masking, Handedness, and Laterality

1974 ◽  
Vol 38 (3) ◽  
pp. 803-811 ◽  
Author(s):  
S. M. Luria
Keyword(s):  
Visual Field ◽  
Left Visual Field ◽  
Visual Masking ◽  
Right Visual Field ◽  
Black Disk ◽  
Left Handed ◽  
Masking Stimulus ◽  
The Right

Monocular thresholds for a black disk and for single letters, presented either alone or followed by a masking stimulus, were obtained for both eyes of 16 left-handed Ss and 16 right-handed Ss. Thresholds for the disk tended to be lower when it was presented to the right visual field, particularly for the left eye and for right-handers. Thresholds for the letters tended to be lower when presented to the right visual field of right-handers and to the left visual field of left-handers. The masking stimulus enhanced these differences for the disk but not for the letters.

scholarly journals Proton–proton, pion–proton and pion–pion diffractive collisions at ultrahigh energies

2014 ◽  
Vol 29 (15) ◽  
pp. 1450096 ◽  
Author(s):  
V. V. Anisovich ◽  
K. V. Nikonov ◽  
V. A. Nikonov ◽  
J. Nyiri
Keyword(s):  
Cross Sections ◽  
Constituent Quark ◽  
Energy Scale ◽  
Proton Proton ◽  
Black Disk ◽  
Total Cross Sections ◽  
Diffractive Dissociation ◽  
Relative Contribution ◽  
Diffractive Scattering ◽  
Dissociation Cross Section

The LHC energies are those at which the asymptotic regime in hadron–hadron diffractive collisions (pp, πp, ππ) might be switched on. Based on results of the Dakhno–Nikonov eikonal model which is a generalization of the Good–Walker eikonal approach for a continuous set of channels, we present a picture for transformation of the constituent quark mode to the black disk one. In the black disk mode [Formula: see text], we have a growth of the logarithm squared type for total and elastic cross-sections, σ tot ~ ln 2 s and σ el ~ ln 2 s and [Formula: see text]-scaling for diffractive scattering and diffractive dissociation of hadrons. The diffractive dissociation cross-section grows as σD ~ ln s, σDD ~ ln s, and their relative contribution tends to zero: σD/σ tot → 0, σDD/σ tot → 0. Asymptotic characteristics of diffractive and total cross-sections are universal, and this results in the asymptotical equality of cross-sections for all types of hadrons (the Gribov universality). The energy scale for switching on the asymptotic mode is estimated for different processes.

scholarly journals Screening and Quantification of Pesticides in Water Using a Dual-Function Graphitized Carbon Black Disk

2011 ◽  
Vol 83 (2) ◽  
pp. 631-631
Author(s):  
Nahid Amini ◽  
Mohammadreza Shariatgorji ◽  
Carlo Crescenzi ◽  
Gunnar Thorsén
Keyword(s):  
Carbon Black ◽  
Graphitized Carbon Black ◽  
Dual Function ◽  
Black Disk ◽  
Graphitized Carbon ◽  
Pesticides In Water
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