1,314 research outputs found
On a Possibility to Determine the Sign of the Polarized Gluon Distribution
We investigate the possibility to draw conclusions on the sign of the
spin-dependent gluon distribution, , from existing polarized
DIS data. The spin-dependent parton distributions , and are constructed
in the framework of a phenomenological procedure taking into account some
assumptions on signs of valence and sea parton distributions motivated by 't
Hooft's mechanism of quark-quark interaction induced by instantons. The axial
gluon anomaly and data on integral quark contributions to the proton spin,
, and , are also taken into
account. Predictions for the - and -dependencies of the polarized
proton and neutron structure functions, and , are compared to
experimental data. It is shown that the neutron structure function, , is
especially sensitive to the sign of . The results of our
analysis supports the conclusion that this sign should be positive.Comment: 14 pages, latex, 12 figure
Is there still a strong CP problem?
The role of a chiral U(1) phase in the quark mass in QCD is analysed from
first principles. In operator formulation, there is a parity symmetry and the
phase can be removed by a change in the representation of the Dirac gamma
matrices. Moreover, these properties are also realized in a Pauli-Villars
regularized version of the theory. In the functional integral scenario,
attempts to remove the chiral phase by a chiral transformation are thought to
be obstructed by a nontrivial Jacobian arising from the fermion measure and the
chiral phase may therefore seem to break parity. But if one starts from the
regularized action with the chiral phase also present in the regulator mass
term, the Jacobian for a combined chiral rotation of quarks and regulators is
seen to be trivial and the phase can be removed by a combined chiral rotation.
This amounts to a taming of the strong CP problem.Comment: 6 pages, REVTeX; brief discussion available at
http://theory.saha.ernet.in/~mitra/scp.htm
Jet Energy Density in Hadron-Hadron Collisions at High Energies
The average particle multiplicity density dN/deta is the dynamical quantity
which reflects some regularities of particle production in low-pT range. The
quantity is an important ingredient of z-scaling. Experimental results on
charged particle density are available for pp, pA and AA collisions while
experimental properties of the jet density are still an open question. The goal
of this work is to find the variable which will reflect the main features of
the jet production in low transverse energy range and play the role of the
scale factor for the scaling function psi(z) and variable z in data
z-presentation. The appropriate candidate is the variable we called "scaled jet
energy density". Scaled jet energy density is the probability to have a jet
with defined ET in defined xT and pseudorapidity regions. The PYTHIA6.2 Monte
Carlo generator is used for calculation of scaled jet energy density in
proton-proton collisions over a high energy range (sqrt s = 200-14000 GeV) and
at eta = 0. The properties of the new variable are discussed and sensitivity to
"physical scenarios" applied in the standard Monte Carlo generator is noted.
The results of scaled jet energy density at LHC energies are presented and
compared with predictions based on z-scaling.Comment: 11 pages, LaTeX, 8 figures, Presented at the XVII International
Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics
& Quantum Chromodynamics", Dubna, Russia, September 27 - October 2, 200
Criminal protection of rights and legal interests of minors
Π ΡΡΠ°ΡΡΠ΅ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΠΊΠ²Π°Π»ΠΈΡΠΈΠΊΠ°ΡΠΈΠΈ ΠΎΠ±ΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎ-ΠΎΠΏΠ°ΡΠ½ΠΎΠ³ΠΎ Π΄Π΅ΡΠ½ΠΈΡ Π² Π²ΠΈΠ΄Π΅ Π½Π΅ΠΎΠ΄Π½ΠΎΠΊΡΠ°ΡΠ½ΠΎΠΉ ΡΠΎΠ·Π½ΠΈΡΠ½ΠΎΠΉ ΠΏΡΠΎΠ΄Π°ΠΆΠΈ Π°Π»ΠΊΠΎΠ³ΠΎΠ»ΡΠ½ΠΎΠΉ ΠΏΡΠΎΠ΄ΡΠΊΡΠΈΠΈ Π½Π΅ΡΠΎΠ²Π΅ΡΡΠ΅Π½Π½ΠΎΠ»Π΅ΡΠ½ΠΈΠΌ.The article is devoted to the analysis of the specialties of qualification of the socially dangerous act like repeated retail sale of alcoholic products to minors
Permafrost hydrology in changing climatic conditions: seasonal variability of stable isotope composition in rivers in discontinuous permafrost
Role of changing climatic conditions on permafrost degradation and hydrology was investigated in the transition zone between the tundra and forest ecotones at the boundary of continuous and discontinuous permafrost of the lower Yenisei River. Three watersheds of various sizes were chosen to represent the characteristics of the regional landscape conditions. Samples of river flow, precipitation, snow cover, and permafrost ground ice were collected over the watersheds to determine isotopic composition of potential sources of water in a river flow over a two year period. Increases in air temperature over the last forty years have resulted in permafrost degradation and a decrease in the seasonal frost which is evident from soil temperature measurements, permafrost and active-layer monitoring, and analysis of satellite imagery. The lowering of the permafrost table has led to an increased storage capacity of permafrost affected soils and a higher contribution of ground water to river discharge during winter months. A progressive decrease in the thickness of the layer of seasonal freezing allows more water storage and pathways for water during the winter low period making winter discharge dependent on the timing and amount of late summer precipitation. There is a substantial seasonal variability of stable isotopic composition of river flow. Spring flooding corresponds to the isotopic composition of snow cover prior to the snowmelt. Isotopic composition of river flow during the summer period follows the variability of precipitation in smaller creeks, while the water flow of larger watersheds is influenced by the secondary evaporation of water temporarily stored in thermokarst lakes and bogs. Late summer precipitation determines the isotopic composition of texture ice within the active layer in tundra landscapes and the seasonal freezing layer in forested landscapes as well as the composition of the water flow during winter months
Photon Physics in Heavy Ion Collisions at the LHC
Various pion and photon production mechanisms in high-energy nuclear
collisions at RHIC and LHC are discussed. Comparison with RHIC data is done
whenever possible. The prospect of using electromagnetic probes to characterize
quark-gluon plasma formation is assessed.Comment: Writeup of the working group "Photon Physics" for the CERN Yellow
Report on "Hard Probes in Heavy Ion Collisions at the LHC", 134 pages. One
figure added in chapter 5 (comparison with PHENIX data). Some figures and
correponding text corrected in chapter 6 (off-chemical equilibrium thermal
photon rates). Some figures modified in chapter 7 (off-chemical equilibrium
photon rates) and comparison with PHENIX data adde
ΠΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½Π°Ρ ΠΈ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²Π΅Π½Π½Π°Ρ ΠΎΡΠ΅Π½ΠΊΠ° Π»ΠΈΠΊΠ²ΠΎΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΠΊΠΈ
Disorders of cerebrospinal fluid (CSF) secretion, dynamics and absorption are common in different illnesses and injuries of the central nervous system (CNS). Nowadays magnetic-resonance tomography (MRI) is the leading research method of CSF dynamics. There are some MRI techniques for both qualitative and quantitative evaluation of CSF dynamic. The assessment of CSF movement is needed to define treatment strategy for patients with different types of hydrocephalus. In this review we have summarized the information about physic basement, area of application of modern MRI techniques. The main attention was paid to modern views on hydrocephalus pathogenesis, pathological CSF flow dynamics in CNS disorders and traumatic brain injury.ΠΠ°ΡΡΡΠ΅Π½ΠΈΡ ΠΏΡΠΎΠ΄ΡΠΊΡΠΈΠΈ, ΡΠΎΠΊΠ° ΠΈ ΡΠ΅Π·ΠΎΡΠ±ΡΠΈΠΈ ΡΠΏΠΈΠ½Π½ΠΎΠΌΠΎΠ·Π³ΠΎΠ²ΠΎΠΉ ΠΆΠΈΠ΄ΠΊΠΎΡΡΠΈ (Π‘ΠΠ) Π²ΡΡΡΠ΅ΡΠ°ΡΡΡΡ ΠΏΡΠΈ ΠΌΠ½ΠΎΠ³ΠΈΡ
Π·Π°Π±ΠΎΠ»Π΅Π²Π°Π½ΠΈΡΡ
ΠΈ ΠΏΠΎΠ²ΡΠ΅ΠΆΠ΄Π΅Π½ΠΈΡΡ
Π½Π΅ΡΠ²Π½ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΡ. Π Π½Π°ΡΡΠΎΡΡΠ΅Π΅ Π²ΡΠ΅ΠΌΡ ΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎ-ΡΠ΅Π·ΠΎΠ½Π°Π½ΡΠ½Π°Ρ ΡΠΎΠΌΠΎΠ³ΡΠ°ΡΠΈΡ (ΠΠ Π’) ΡΠ²Π»ΡΠ΅ΡΡΡ Π²Π΅Π΄ΡΡΠΈΠΌ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ Π»ΠΈΠΊΠΎΠ²ΠΎΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΠΊΠΈ. ΠΠ° ΡΠ΅Π³ΠΎΠ΄Π½ΡΡΠ½ΠΈΠΉ Π΄Π΅Π½Ρ ΠΈΠ·Π²Π΅ΡΡΠ½ΠΎ Π½Π΅ΡΠΊΠΎΠ»ΡΠΊΠΎ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ, ΠΊΠΎΡΠΎΡΡΠ΅ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΠΎΡΠ΅Π½ΠΈΡΡ ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠ΅ ΠΈ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ ΡΠΏΠΈΠ½Π½ΠΎΠΌΠΎΠ·Π³ΠΎΠ²ΠΎΠΉ ΠΆΠΈΠ΄ΠΊΠΎΡΡΠΈ. ΠΡΠ΅Π½ΠΊΠ° Π»ΠΈΠΊΠ²ΠΎΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΠΊΠΈ Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠ° Π΄Π»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΏΡΠ°Π²ΠΈΠ»ΡΠ½ΠΎΠΉ ΡΠ°ΠΊΡΠΈΠΊΠΈ Π»Π΅ΡΠ΅Π½ΠΈΡ ΠΏΠ°ΡΠΈΠ΅Π½ΡΠΎΠ² Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠΌΠΈ Π²ΠΈΠ΄Π°ΠΌΠΈ Π³ΠΈΠ΄ΡΠΎΡΠ΅ΡΠ°Π»ΠΈΠΈ. Π ΠΎΠ±Π·ΠΎΡΠ΅ Π»ΠΈΡΠ΅ΡΠ°ΡΡΡΡ ΠΏΡΠΈΠ²Π΅Π΄Π΅Π½Ρ ΡΠΈΠ·ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΎΡΠ½ΠΎΠ²Ρ, ΠΎΠ±Π»Π°ΡΡΠΈ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΡ
ΠΠ Π’-ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ Π»ΠΈΠΊΠ²ΠΎΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΠΊΠΈ. ΠΡΠΎΠ±ΠΎΠ΅ Π²Π½ΠΈΠΌΠ°Π½ΠΈΠ΅ ΡΠ΄Π΅Π»Π΅Π½ΠΎ ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌ Π²Π·Π³Π»ΡΠ΄Π°ΠΌ Π½Π° ΠΏΠ°ΡΠΎΠ³Π΅Π½Π΅Π· Π³ΠΈΠ΄ΡΠΎΡΠ΅ΡΠ°Π»ΠΈΠΈ, ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΡΠΌ ΡΠΎΠΊΠ° Π»ΠΈΠΊΠ²ΠΎΡΠ° ΠΏΡΠΈ ΡΠ°Π·Π»ΠΈΡΠ½ΡΡ
Π·Π°Π±ΠΎΠ»Π΅Π²Π°Π½ΠΈΡΡ
ΡΠ΅Π½ΡΡΠ°Π»ΡΠ½ΠΎΠΉ Π½Π΅ΡΠ²Π½ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΡ ΠΈ ΡΠ΅ΡΠ΅ΠΏΠ½ΠΎ-ΠΌΠΎΠ·Π³ΠΎΠ²ΠΎΠΉ ΡΡΠ°Π²ΠΌΠ΅
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