45 research outputs found
Vacuum creation of quarks at the time scale of QGP thermalization and strangeness enhancement in heavy-ion collisions
The vacuum parton creation in quickly varying external fields is studied at
the time scale of order 1 fm/ typical for the quark-gluon plasma formation
and thermalization. To describe the pre-equilibrium evolution of the system the
transport kinetic equation is employed. It is shown that the dynamics of
production process at times comparable with particle inverse masses can deviate
considerably from that based on classical Schwinger-like estimates for
homogeneous and constant fields. One of the effects caused by non-stationary
chromoelectric fields is the enhancement of the yield of quark
pairs. Dependence of this effect on the shape and duration of the field pulse
is studied together with the influence of string fusion and reduction of quark
masses.Comment: REVTEX, 11pp. incl. 4 figures, to be published in Phys. Lett.
Strong Decays of Strange Quarkonia
In this paper we evaluate strong decay amplitudes and partial widths of
strange mesons (strangeonia and kaonia) in the 3P0 decay model. We give
numerical results for all energetically allowed open-flavor two-body decay
modes of all nsbar and ssbar strange mesons in the 1S, 2S, 3S, 1P, 2P, 1D and
1F multiplets, comprising strong decays of a total of 43 resonances into 525
two-body modes, with 891 numerically evaluated amplitudes. This set of
resonances includes all strange qqbar states with allowed strong decays
expected in the quark model up to ca. 2.2 GeV. We use standard nonrelativistic
quark model SHO wavefunctions to evaluate these amplitudes, and quote numerical
results for all amplitudes present in each decay mode. We also discuss the
status of the associated experimental candidates, and note which states and
decay modes would be especially interesting for future experimental study at
hadronic, e+e- and photoproduction facilities. These results should also be
useful in distinguishing conventional quark model mesons from exotica such as
glueballs and hybrids through their strong decays.Comment: 69 pages, 5 figures, 39 table
Chondrules – ubiquitous chondritic solids tracking the evolution of the solar protoplanetary disk
Features of adaptation of photosynthesis of winter wheat plant leaves to growing conditions
Depending on the growing conditions, the intensity of photosynthesis of winter wheat plant leaves varies from 7.58 to 15.76 µmol CO2/m2s, significantly decreasing (on average by 41%) in dry and hot weather. During the day, its value varies from 7.07 to 12.48 µmol CO2/m2s, reaching a maximum (12.48 µmol CO2/m2s) in the morning (from 9:00 to 11:00 am), when the air temperature is not so high (from 18 to 23°C), and the light becomes saturating (1000 -1300 µmol/m2s). In the time following, the intensity of leaf photosynthesis decreases, reaching the minimum values at 7:00 pm. At the same time, the flag leaves of plants are characterized by the highest photosynthetic activity - from 12.56 to 16.16 µmol CO2/m2s, exceeding the pre-flag leaves by 1.6 times, and the lower ones by 3.1 times. The stomatal apparatus plays an important role in the adaptation of leaf photosynthesis to environmental factors. The correlation coefficient of photosynthesis intensity with stomatal conductivity in different leaf locations varied from 0.97 to 0.98
Investigation by mass spectrometer of the kinetics of thermal degradation of polystyrene and its connection with mechanical rupture
Neoproterozoic extension in the greater dharwar craton: A reevaluation of the "betsimisaraka suture" in madagascarn
The Precambrian shield of Madagascar is reevaluated with recently compiled geological data and new U-Pb sensitive high-resolution ion microprobe (SHRIMP) geochronology. Two Archean domains are recognized: the eastern Antongil-Masora domain and the central Antananarivo domain, the latter with distinctive belts of metamafic gneiss and schist (Tsaratanana Complex). In the eastern domain, the period of early crust formation is extended to the Paleo-Mesoarchean (3.32-3.15 Ga) and a supracrustal sequence (Fenerivo Group), deposited at 3.18 Ga and metamorphosed at 2.55 Ga, is identified. In the central domain, a Neoarchean period of high-grade metamorphism and anatexis that affected both felsic (Betsiboka Suite) and mafic gneisses (Tsaratanana Complex) is documented. We propose, therefore, that the Antananarivo domain was amalgamated within the Greater Dharwar Craton (India + Madagascar) by a Neoarchean accretion event (2.55-2.48 Ga), involving emplacement of juvenile igneous rocks, high-grade metamorphism, and the juxtaposition of disparate belts of mafic gneiss and schist (metagreenstones). The concept of the "Betsimisaraka suture" is dispelled and the zone is redefined as a domain of Neoproterozoic metasedimentary (Manampotsy Group) and metaigneous rocks (Itsindro-Imorona Suite) formed during a period of continental extension and intrusive igneous activity between 840 and 760 Ma. Younger orogenic convergence (560-520 Ma) resulted in east-directed overthrusting throughout south Madagascar and steepening with local inversion of the domain in central Madagascar. Along part of its length, the Manampotsy Group covers the boundary between the eastern and central Archean domains and is overprinted by the Angavo-Ifanadiana high-strain zone that served as a zone of crustal weakness throughout Cretaceous to Recent times
A new geological framework for south-central Madagascar, and its relevance to the "out-of-Africa" hypothesis
The Precambrian shield of south-central Madagascar, excluding the Vohibory region, consists of three geologic domains, from north to south: Antananarivo, Ikalamavony-Itremo, and Anosyen-Androyen. The northern Antananarivo domain represents the Neoarchea
A partial wave analysis of anti-p p --> eta eta pi0
AbstractA partial wave analysis of p̄p→ηηπ0 data from the Crystal Barrel experiment is made in terms of s-channel resonances. The decay channels a0(980)η, f0(1770)π and f0(2105)π provide evidence for two I=1, JPC=0−+ resonances. The first has mass M=2360±25 MeV and width Γ=300+100−50 MeV, and the second M=2070±35 MeV, Γ=310+100−50 MeV. There is also evidence for a JPC=2−+ state with M=2005±15 MeV and Γ=200±40 MeV, decaying strongly to a0(980)π
Partial wave analysis of anti-p p annihilation channels in flight with I = 1, C = +1
A combined analysis is reported of 3pizero, pizero-eta and pizero-etaprime
data in the mass range 1960 to 2410 MeV. This analysis is made consistent also
with eta-eta-pizero data, reported separately. The analysis requires s-channel
resonances with a spectrum close to that published earlier for C = +1 states
with I = 0; masses for I=1 states are lower on average by 20 MeV. Two
alternative solutions are found, differing only for J^P = 2^+ and 4^+ states by
small amounts in masses and widths. Both 3pizero and eta-pizero data prefer one
of these two solutions. For this preferred solution, observed states have J^PC,
masses and widths (M,Gamma) in MeV as follows: 4^-+: (2250+-15, 215+-25), 4^++:
(2255+-40, 330 ^{+110}_{-50}) and (2005 ^{+25}_{-45}, 180+-30), 3^++:
(2275+-35, 350 ^{+100}_{-50}) and (2031+-12, 150 \pm 18), 2^-+: (2245+-60, 320
^{+100}_{-40}) and (2005+-15, 200+-40, 2^++: (2255+-20, 230+-15), (2175+-40,
310^{+90}_{-45}) and (2030+-20, 205+-30), and 1^++: (2270 ^{+55}_{-40}, 305
^{+70}_{-35}). There are indications of further 2^-+, 2^++ and 1^++
contributions just below the available mass range, and also a 0^++ state at
~2025 MeV.Comment: Final combined analysis of 4 sets of data with these quantum number