The cross sections of J/ψ ηc and J/ψ J/ψ production in e+ e− annihilation are calculated at a one-loop accuracy near Z -boson pole and at higher energies as well. Both intermediate bosons, γ and Z ..., are included. It is found that at Z mass, the next-to-leading contribution increases the production cross sections by a factor of 3.5.
Doubly heavy baryons at the LHC Berezhnoy, A. V.; Likhoded, A. K.; Luchinsky, A. V.
Physical review. D,
12/2018, Letnik:
98, Številka:
11
Journal Article
Recenzirano
Odprti dostop
The theoretical analysis of production, lifetime, and decays of doubly heavy baryons is presented. The lifetime of Ξ++cc baryons recently measured by the LHCb Collaboration is used to estimate the ...lifetimes of other doubly heavy baryons. The production and the possibility of observation of Ξbc baryons at the LHC are discussed.
The strongest gamma-ray burst (GRB) of the century, GRB20221009A, has been detected by the Korean Pathfinder Lunar Orbiter Gamma-ray Spectrometer (KGRS) instrument onboard the Korean Pathfinder Lunar ...Orbiter (KPLO). KGRS uses a LaBr3 detector to measure GRB counts with five energy bins in the energy range from 30 keV to 12 MeV. KGRS detected GRB221009A at a distance of 1.508 million kilometers from the Earth. The full duration of the main burst was recorded between 13:20 and 13:26 on October 9, 2022 with peak counts of over 1000 times background. The dead time of KGRS reached as high as 50%, and the intrinsic gamma-ray spectrum of LaBr3 was significantly altered.
We calculated the cross sections of photolysis of OH, LiO, NaO, KO, HCl, LiCl, NaCl, KCl, HF, LiF, NaF, and KF molecules using quantum chemistry methods. The maximal values for photolysis cross ...sections of alkali metal monoxides are on the order of 10
−18
cm
2
. The lifetimes of photolysis for quiet Sun at 1 astronomical unit are estimated as 2.0 × 10
5
, 28, 5, 14, 2.1 × 10
5
, 225, 42, 52, 2 × 10
6
, 35 400, 486, and 30 400 s for OH, LiO, NaO, KO, HCl, LiCl, NaCl, KCl, HF, LiF, NaF, and KF, respectively. We performed a comparison between values of photolysis lifetimes obtained in this work and in previous studies. Based on such a comparison, our estimations of photolysis lifetimes of OH, HCl, and HF have an accuracy of about a factor of 2. We determined typical kinetic energies of main peaks of photolysis-generated metal atoms. Impact-produced LiO, NaO, KO, NaCl, and KCl molecules are destroyed in the lunar and Hermean exospheres almost completely during the first ballistic flight, while other considered molecules are more stable against destruction by photolysis.
• FeO, CaO, AlO, MgO and probably also N2 bands were detected.• CaO/FeO ratio strongly increased toward lower altitudes, while AlO/FeO did not.• MgO bands were fainter than AlO bands contrary to ...expectations.• Vibrational (3000K) and rotational (1000K) temperatures of AlO were different.• AlO non-equilibrium can be explained by short hydrodynamic timescales.
We analyzed molecular radiation in the spectra of the very bright Benešov bolide. The Benešov bolide appeared over the Czech Republic on May 7, 1991 and reached an absolute magnitude of –19.5. It was caused by a meteoroid larger than 1m. Small meteorites of various mineralogical types were recovered recently (Spurný et al. 2014 Astron. Astrophys., 570, A39, 14 p.). The spectrum of the bolide, recorded on two photographic plates, is probably the richest meteor spectrum ever obtained. It contains hundreds of atomic emission lines, continuous radiation and molecular bands, and covers the whole bolide trajectory from the altitude of 90–20km. In this paper we focus on identification and analysis of molecular bands. The identification of FeO, CaO, AlO, and MgO, reported earlier (Borovička and Spurný 1996 Icarus, 121, 484–510) was confirmed. In addition, radiation of N2 was probably detected. The oxides were best seen in the wake and in the radiating cloud left at the position of the bolide flare at the altitude of 24.5km. Trace of N2 was seen only in the meteor at lower altitudes. FeO bands are present in the spectra from the highest altitudes. We suppose that FeO was ablated directly in molecular form at high altitudes. CaO was first detected just below 50km and its intensity, relatively to FeO, strongly increased toward lower altitudes. AlO, which is similarly refractive as CaO, behaved as FeO rather than CaO at lower altitudes. MgO was observed only in the radiating cloud. The spectrum of the cloud is unique because it contains almost no atomic lines. We compared the data with theoretical calculations of the presence of molecules in the mixture of meteoric vapors and air at various altitudes and temperatures. CN and TiO were not found. The upper limit of CN is in agreement with theory for ordinary chondrite meteoroid. Most of carbon should be in fact present in the form of CO, but CO bands are too weak to be detected. The non-detection of TiO can be explained by the fact that temperature in the wake and the cloud was lower than needed for the presence of TiO bands. However, AlO was found to be about 40 times more abundant than MgO, although comparable abundances are expected. The explanation may be that the abundances are in fact comparable but there are non-equilibrium conditions in the radiating cloud with the excitation temperature of MgO lower than that of AlO. The difference may be caused by higher ablation temperature of Al. Another non-equilibrium effect is the observed difference between the rotational (∼1000K) and vibrational (∼3000K) temperature of AlO molecules. This can be explained by short hydrodynamic timescale and the fact that vibrational relaxation time is significantly longer than rotational relaxation time. The vibrational temperature therefore could not decrease so quickly during the cooling and expansion of the cloud because of insufficient number of collisions. FeO and CaO could not be analyzed in detail, because their molecular constants, especially transition probabilities, are not well known. The increase of the CaO/FeO ratio with decreasing altitude could be, nevertheless, explained in scope of equilibrium chemistry.
•Chemical processes during collisions between meteoroids and the Moon are considered.•Chemistry of Na-, K-, Li-, Mg-, Fe-, Al-, Ca-, and Si-containing species is studied.•Photolysis lifetimes of main ...impact-produced species are estimated.•Formation of dust particles decreases the content of atoms in the lunar exosphere.
Based on the equilibrium thermochemical approach and quenching theory, the formation of Na-, K-, Li-, Si-, Ca-, Al-, Mg-, and Fe-bearing molecules and dust particles in impact-produced clouds formed after collisions between meteoroids and the Moon is considered. Photolysis lifetimes and energies of photolysis products of oxides and hydroxides of the main elements are estimated. The estimated fraction of uncondensed species, and list of the main molecules and their properties regarding photolysis during impact processes may be useful for the analysis of future observations of atoms of alkali and refractory elements in the exospheres of the Moon and Mercury.
Water ice, abundant in the outer solar system, is volatile in the inner solar system. On the largest airless bodies of the inner solar system (Mercury, the Moon, Ceres), water can be an exospheric ...species but also occurs in its condensed form. Mercury hosts water ice deposits in permanently shadowed regions near its poles that act as cold traps. Water ice is also present on the Moon, where these polar deposits are of great interest in the context of future lunar exploration. The lunar surface releases either OH or H
2
O during meteoroid showers, and both of these species are generated by reaction of implanted solar wind protons with metal oxides in the regolith. A consequence of the ongoing interaction between the solar wind and the surface is a surficial hydroxyl population that has been observed on the Moon. Dwarf planet Ceres has enough gravity to have a gravitationally-bound water exosphere, and also has permanently shadowed regions near its poles, with bright ice deposits found in the most long-lived of its cold traps. Tantalizing evidence for cold trapped water ice and exospheres of molecular water has emerged, but even basic questions remain open. The relative and absolute magnitudes of sources of water on Mercury and the Moon remain largely unknown. Exospheres can transport water to cold traps, but the efficiency of this process remains uncertain. Here, the status of observations, theory, and laboratory measurements is reviewed.
Sodium and, in a lesser way, potassium atomic components of surface-bounded exospheres are among the brightest elements that can be observed from the Earth in our Solar System. Both species have been ...intensively observed around Mercury, the Moon and the Galilean Moons. During the last decade, new observations have been obtained thanks to space missions carrying remote and in situ instrumentation that provide a completely original view of these species in the exospheres of Mercury and the Moon. They challenged our understanding and modelling of these exospheres and opened new directions of research by suggesting the need to better take into account the relationship between the surface-exosphere and the magnetosphere. In this paper, we first review the large set of observations of Mercury and the Moon Sodium and Potassium exospheres. In the second part, we list what it tells us on the sources and sinks of these exospheres focusing in particular on the role of their magnetospheres of these objects and then discuss, in a third section, how these observations help us to understand and identify the key drivers of these exospheres.
We used ICP–MS to measure the elemental concentrations and isotopic abundances of Cu and Zn in: nine Ti-rich lunar basalts (10017, 10022, 10024, 10057, 70215, 71055, 74255, 75055, and 75075); ...size-separated samples prepared by sieving of pyroclastic black glass 74001, orange glass 74022, and the lunar soils 15021, 15231, 70181, and 79221; a basalt from the Piton des Neiges volcano, Reunion Island; two samples of Pele’s hairs from the Nyiragongo volcano, Democratic Republic of Congo, and the martian meteorite Zagami.
The isotopic fractionation of zinc in lunar basalts and Zagami is mass dependent relative to a terrestrial standard (JMC 400882B). These and published results imply that lunar, terrestrial, meteoritic, and perhaps martian zinc all come from one or more reservoirs linked by mass-dependent fractionation processes. Relative to terrestrial basalts, Ti-rich lunar basalts are enriched in the heavier isotopes of Cu and Zn: we find for Ti-rich lunar basalts the following ranges and averages ±1
−
σ (‰): δ
65Cu/
63Cu
≡
δ
65Cu, 0.1–1.4, 0.5
±
0.1‰ (
N
=
7); δ
66Zn/
64Zn
≡
δ
66Zn
=
0.2–1.9, 1.2
±
0.2‰ (
N
=
8; 10017 excluded). For two terrestrial samples, we find δ
66Zn
∼
+0.3‰ and δ
65Cu
∼
0‰, which are consistent with published values. The differences between the lunar basalts and terrestrial basalts could reflect minor, planetary-scale vaporization or igneous processes on the Moon.
Data for size separates of the pyroclastic glasses 74001 and 74220 confirm the well-known surface correlation of Cu and Zn, but modeling calculations reveal no sharp differences between either the elemental ratios or the isotopic composition of grain interiors and exteriors. The absence of such differences indicates that the isotopic compositions for bulk samples are dominated by a light-isotope-rich surface component.
Data for size separates of lunar soils also confirm the surface correlation of Cu and Zn, but an enrichment of heavy rather than light isotopes. Averages for bulk lunar soils from this work and the literature are (‰): δ
65Cu, from 1.4 to 4.1, average 3.0
±
0.3 (
N
=
9); δ
66Zn, from 2.2 to 6.4, average 4.0
±
0.3 (
N
=
14). As with the glasses, in all but soil 15231 our data show no strong differences between the isotopic composition of soil sub-samples with small and large grains.
The size of the isotopic fractionation inferred for the surface component in the soils is 3× smaller than predicted by a published model of sputtering primarily by solar particles. At the same time, the observed fractionation is larger than predicted by calculations based on a model of micrometeorite impact heating and hydrodynamic quenching. Because impact heating appears unable to explain the observations, we conclude that sputtering must be important even though samples with very large isotopic fractionation of Cu and Zn have not yet been found.
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