100 research outputs found
Incoherent diffractive photoproduction of and on heavy nuclei in the color dipole approach
We calculate cross sections and transverse momentum distributions for the
incoherent diffractive production of vector mesons and on
heavy nuclei. In distinction to coherent diffraction, the nucleus is allowed to
break up, but except for the vector meson no new particles are produced in the
reaction. Within the color dipole approach, we derive the multiple scattering
expansion of the incoherent diffractive cross section as an expansion over
quasielastic scatterings of the color dipole. We also compare our results to
the measurement of the ALICE collaboration for incoherent production
at and show predictions at
. We also briefly discuss a possible
contribution to production in peripheral collisions in the centrality class.Comment: 18 pages, 8 fig
Unintegrated gluon distributions from the color dipole cross section in the BGK saturation model
We evaluate the unintegrated gluon distribution of the proton starting from a
parametrization of the color dipole cross section including DGLAP evolution and
saturation effects. To this end, we perform the Fourier-Bessel transform of
. At large transverse momentum of gluons we match the
so-obtained distribution to the logarithmic derivative of the collinear gluon
distribution. We check our approach by calculating the proton structure
function finding good agreement with HERA data.Comment: 4 pages, 3 fig
Diffractive production of electroweak vector bosons at the LHC
We analyse diffractive electroweak vector boson production in hadronic
collisions and show that the single diffractive W boson production asymmetry in
rapidity is a particularly good observable at the LHC to test the concept of
the flavour symmetric pomeron parton distributions. It may also provide an
additional constraint for the parton distribution functions in the proton.Comment: 7 pages, 5 figure
Probing proton structure with correlations in ultraperipheral collisions
We study the exclusive diffractive photoproduction in
ultraperipheral collisions. The formalism makes use of off-diagonal
generalizations of the unintegrated gluon distribution, the so-called
generalized transverse momentum dependent distributions (GTMDs). We present two
different formulations. The first one is based directly on gluon GTMD
parametrizations in momentum space. Another option is the calculation of the
GTMD as a Fourier transform of the dipole-nucleon scattering amplitude
. The latter approach requires some extra
regularization discussed in the paper. Different dipole amplitudes from the
literature are used. Compared to previous calculations in the literature, we
integrate over the full phase space and therefore cross sections for realistic
conditions are obtained. We present distributions in rapidity of or , transverse momentum of the pair, four-momentum transfer squared
as well as the azimuthal correlation between a sum and a difference of the
and transverse momenta. The azimuthal correlations are partially due
to the so-called elliptic gluon Wigner distribution. Different models lead to
different modulations in the azimuthal angle. The modulations are generally
smaller than 5%. They depend on the range of transverse momentum selected for
the calculation.Comment: 22 pages, 14 figures, 1 tabl
Production of heavy particle pairs via photon-photon processes at the LHC
We discuss production of pairs and quark-antiquark pairs
in proton-proton collisions induced by two-photon fusion including transverse
momenta of incoming photons. The unintegrated inelastic fluxes (related to
proton dissociation) of photons are calculated based on modern parametrizations
of deep inelastic structure functions in a broad range of and . We
focus on processes with single and double proton dissociation. Highly excited
remnant systems hadronise producing particles that can be vetoed in the
calorimeter. We calculate associated gap survival factors. The gap survival
factors depend on the process, mass of the remnant system and collision energy.
The rapidity gap survival factor due to remnant fragmentation for double
dissociative (DD) collisions is smaller than that for single dissociative (SD)
process. We observe approximate factorisation:
when imposing rapidity veto. For the final state, the remnant
fragmentation leads to a taming of the cross section when the rapidity gap
requirement is imposed. Also for quark-antiquark pairs such a
condition reverses the hierarchy observed for the case when such condition is
taken into account. Our results imply that for the production of such heavy
objects as quark and antiquark the virtuality of the photons
attached to the dissociative system are very large ( 10 GeV).
A similar effect is observed for the system.Comment: 11 pages, 9 figures, a talk presented by Marta {\L}uszczak at XXVI
Cracow EPIPHANY Conference, LHC Physics: Standard Model and Beyond, 7-10
January 202
Charmed Meson Production in Proton - (ANTI)PROTON Collisions
We discuss and compare different approaches to include gluon transverse
momenta for heavy quark-antiquark pair and meson production. The results are
illustrated with the help of different unintegrated gluon distributions (UGDF)
from the literature. We compare results obtained with on-shell and off-shell
matrix elements and kinematics. The results are compared with recent
experimental results of the CDF collaboration.Comment: presented by M. Luszczak at the international conference MESON2006,
June 2006, Cracow, 6 pages, 5 figure
Unintegrated gluon distributions and Higgs boson production in proton-proton collisions
Inclusive cross sections for Higgs boson production in proton-proton
collisions are calculated in the formalism of unintegrated gluon distributions
(UGDF). Different UGDF from the literature are used. Although they were
constructed in order to describe the HERA deep-inelastic scattering data,
they lead to surprisingly different results for Higgs production. We present
both two-dimensional invariant cross section as a function of Higgs rapidity
and transverse momentum, as well as corresponding projections on rapidity or
transverse momentum. We quantify the differences between different UGD's by
applying different cuts on interrelations between transverse momentum of Higgs
and transverse momenta of both fusing gluons. We focus on 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
50-100 GeV the weak-gauge-boson fusion dominates over gluon-gluon fusion.Comment: 32 pages, 18 figures, corrected version, restructured, misprints
removed, discussion added, new figure added, in print in EPJ
Space Mixing
Prezentowane działania dotyczą poszukiwania nowych metod
dydaktycznych związanych z kształceniem nauczycieli na
kierunku edukacja artystyczna w zakresie sztuk plastycznych,
realizowanym na Uniwersytecie Śląskim w Katowicach
w Instytucie Sztuki w Cieszynie. Aktualna sytuacja sztuki
charakteryzuje się dużą złożonością, która spowodowana jest
z jednej strony kontekstem teoretycznym modernizmu i inwazją
kultury popularnej, a z drugiej – pojawieniem się w sztuce
nowych mediów, takich jak: plastyczne działania intermedialne
i multimedialne, art netu oraz zróżnicowanych praktyk artystycznych.
Nowa rzeczywistość stawia nowe zadania przed
nauczycielami. Przygotowując ich do zawodu, nie należy
zapominać o złożoności tego problemu i ograniczać się jedynie
do działań warsztatowych i historii sztuki (wartości poszczególnych
dzieł). Interdyscyplinarne podejście do uczestnictwa
w kulturze wizualnej wydaje się najbardziej słusznym rozwiązaniem.
Przykładem działań interdyscyplinarnych są nowe
standardy kształcenia nauczycieli w Polsce, które koncentrują
się na szeroko rozumianych kategoriach tematycznych,
np. człowiek i media, a w mniejszym stopniu opisują techniki
plastyczne. Dyskurs prowadzony na uniwersytetach, zajmujących
się kształceniem nauczycieli, zmierza do poszukiwania
nowych koncepcji i metod, które pozwoliłyby na edukację
dostosowaną do wymogów i potrzeb współczesnego świata.
Zespół nauczycieli Katedry Interdyscyplinarnej Kreacji
Artystycznej podejmuje szereg działań edukacyjno-artystycznych.
W ich ramach wykorzystywane są zarówno tradycyjne
narzędzia i techniki, jak również rzeczywistość wirtualna
i rzeczywistość rozszerzona. Artykuł prezentuje kilkanaście
warsztatów zrealizowanych na Uniwersytecie Śląskim w Cieszynie, a także w ramach międzynarodowych projektów,
takich jak Lifelong Learning Programme w Austrii, Czechach
i we Włoszech
Quantifying uplift and denudation of a thermally heterogeneous crust: a detailed multi-thermochronometeric study of central west Britain
Topography is often thought as exclusively linked to mountain ranges formed by plates collision. It is now, however, known that apart from compression, uplift and denudation of rocks may be triggered by rifting, like it happens at elevated passive margins, and away from plate boundaries by both intra-plate stress causing reactivation of older structures, and by epeirogenic movements driven by mantle dynamics and initiating long-wavelength uplift. In the Cenozoic, central west Britain and other parts of the North Atlantic margins experienced multiple episodes of rock uplift and denudation that have been variable both at spatial and temporal scales. The origin of topography in central west Britain is enigmatic, and because of its location, it may be related to any of the processes mentioned above.
In this study, three low temperature thermochronometers, the apatite fission track (AFT) and apatite and zircon (U-Th-Sm)/He (AHe and ZHe, respectively) methods were used to establish the rock cooling history from 200◦C to 30◦C. The samples were collected from the intrusive rocks in the high elevation, high relief regions of the Lake District (NW England), southern Scotland and northern Wales. AFT ages from the region are youngest (55–70 Ma) in the Lake District and increase northwards into southern Scotland and southwards in north Wales (>200 Ma). AHe and ZHe ages show no systematic pattern; the former range from 50 to 80 Ma and the latter tend to record the post-emplacement cooling of the intrusions (200–400 Ma).
The complex, multi-thermochronometric inverse modelling suggests a ubiquitous, rapid Late Cretaceous/early Palaeogene cooling event that is particularly marked in Lake District and Criffell. The timing and rate of cooling in southern Scotland and in northern Wales is poorly resolved as the amount of cooling was less than 60◦C. The Lake District plutons were at >110◦C prior to the early Palaeogene; cooling due to a combined effect of high heat flow, from the heat producing granite batholith, and the blanketing effect of the overlying low conductivity Late Mesozoic limestones and mudstones. Modelling of the heat transfer suggests that this combination produced an elevated geothermal gradient within the sedimentary rocks (50–70◦C/km) that was about two times higher than at the present day. Inverse modelling of the AFT and AHe data taking the crustal structure into consideration suggests that denudation was the highest, 2.0–2.5 km, in the coastal areas of the Lake District and southern Scotland, gradually decreasing to less than 1 km in the northern Southern Uplands and northern Wales.
Both the rift-related uplift and the intra-plate compression poorly correlate with the timing, location and spatial distribution of the early Palaeogene denudation. The pattern of early Palaeogene denudation correlates with the thickness of magmatic underplating, if the changes of mean topography, Late Cretaceous water depth and eroded rock density are taken into consideration. However, the uplift due to underplating alone cannot fully justify the total early Palaeogene denudation. The amount that is not ex- plained by underplating is, however, roughly spatially constant across the study area and can be referred to the transient thermal uplift induced by the mantle plume arrival. No other mechanisms are required to explain the observed pattern of denudation. The onset of denudation across the region is not uniform. Denudation started at 70–75 Ma in the central part of the Lake District whereas the coastal areas the rapid erosion appears to have initiated later (65–60 Ma). This is ~10 Ma earlier than the first vol- canic manifestation of the proto-Iceland plume and favours the hypothesis of the short period of plume incubation below the lithosphere before the volcanism.
In most of the localities, the rocks had cooled to temperatures lower than 30◦C by the end of the Palaeogene, suggesting that the total Neogene denudation was, at a maximum, several hundreds of metres. Rapid cooling in the last 3 million years is resolved in some places in southern Scotland, where it could be explained by glacial erosion and post-glacial isostatic uplift
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