Implications of Catalyzed BBN in the CMSSM with Gravitino Dark Matter

We investigate gravitino dark matter scenarios in which the primordial ^6Li production is catalyzed by bound-state formation of long-lived negatively charged particles X^- with ^4He. In the constrained minimal supersymmetric Standard Model (CMSSM) with the stau^- as the X^-, the observationally inferred bound on the primordial ^6Li abundance allows us to derive a rigid lower limit on the gaugino mass parameter for a standard cosmological history. This limit can have severe implications for supersymmetry searches at the Large Hadron Collider and for the reheating temperature after inflation.Comment: 4 pages, 2 figures; note and paragraph added; references updated

Reconciling evidence from ancient and contemporary genomes: a major source for the European Neolithic within Mediterranean Europe

Important gaps remain in our understanding of the spread of farming into Europe, due partly to apparent contradictions between studies of contemporary genetic variation and ancient DNA. It seems clear that farming was introduced into central, northern, and eastern Europe from the south by pioneer colonization. It is often argued that these dispersals originated in the Near East, where the potential source genetic pool resembles that of the early European farmers, but clear ancient DNA evidence from Mediterranean Europe is lacking, and there are suggestions that Mediterranean Europe may have resembled the Near East more than the rest of Europe in the Mesolithic. Here, we test this proposal by dating mitogenome founder lineages from the Near East in different regions of Europe. We find that whereas the lineages date mainly to the Neolithic in central Europe and Iberia, they largely date to the Late Glacial period in central/eastern Mediterranean Europe. This supports a scenario in which the genetic pool of Mediterranean Europe was partly a result of Late Glacial expansions from a Near Eastern refuge, and that this formed an important source pool for subsequent Neolithic expansions into the rest of Europ

Probing the Reheating Temperature at Colliders and with Primordial Nucleosynthesis

Considering gravitino dark matter scenarios with a long-lived charged slepton, we show that collider measurements of the slepton mass and its lifetime can probe not only the gravitino mass but also the post-inflationary reheating temperature TR. In a model independent way, we derive upper limits on TR and discuss them in light of the constraints from the primordial catalysis of lithium-6 through bound-state effects. In the collider-friendly region of slepton masses below 1 TeV, the obtained conservative estimate of the maximum reheating temperature is about TR=3\times 10^9 GeV for the limiting case of a small gluino-slepton mass splitting and about TR=10^8 GeV for the case that is typical for universal soft supersymmetry breaking parameters at the scale of grand unification. We find that a determination of the gluino-slepton mass ratio at the Large Hadron Collider will test the possibility of TR>10^9 GeV and thereby the viability of thermal leptogenesis with hierarchical heavy right-handed Majorana neutrinos.Comment: 10 pages, 3 figures; revised version (references added, minor corrections

Achieving high quality surface of laminated glass-reinforced plastics during milling

Milling is one of the most common ways of workpiece machining, but obtaining a high quality surface of laminated composite materials is difficult due to their layered structure, high strength characteristics and low heat conductivity. This poses a problem of creating a milling technology that provides a high quality surface. This research investigates STEF -1 glass-fiber plastic with fine grain structure processed on the equipment with high cutting speed. The object of the research is roughness Ra as a quality criterion. Our glass-fiber plastic milling experiments demonstrate that the surface quality depends to a large extent on the cutting modes and the wear level of the tool cutting edge which is determined by the size of the wear bevel on the flank surface. The blade of the cutting tool is established to wear unevenly during glass-fiber plastic processing as it interacts with two different materials. We recommend the wear bevel on the flank surface to be less than 0.35 mm to ensure the high quality of the laminated composite material surface. The cutting modes should be within the following range: feed per tooth is 0.15 ÷ 0.17 mm/tooth, cutting depth is 0.5 ÷ 0.9 mm, cutting speed is above 45 m/s, with the cutting part of the tool being made of high-strength instrumental materials

Defects in diamonds as the basic adhesion grinding

Defects arising in diamond crystals during their synthesis, give rise to the formation of more complex defects that arise in the operational process of diamonds themselves. In case of external action these defects have immediate strong effect on operating characteristics of devices, products or tools containing diamonds. When external action these defects and have immediate strong effect on production characteristics of devices, products or instruments containing diamonds. This is particularly manifested in the grinding of tough, ductile materials based on aluminum, magnesium or titanium. Developed on the basis of modern digital technology and molecular dynamics visualization method allows to show it at the atomic level. The problems of practical application of the combined electric diamond grinding are examined. Experiments were conducted on the grinding tool materials with metal-bonded diamond grinding wheels

Adhesive wear mechanism under combined electric diamond grinding

The article provides a scientific substantiation of loading of metal-bond diamond grinding wheels and describes the mechanism of contact interaction (interlocking) of wheels with tool steel as well as its general properties having an influence on combined electric diamond grinding efficiency. The study concluded that a loaded layer can be formed in a few stages different by nature. It is known, that one of the causes of grinding degradation is a continuous loading of active grits (abrasive grinding tool) by workpiece chips. It all affects the diamond grinding wheels efficiency and grinding ability with a result in increase of tool pressure, contact temperature and wheels specific removal rate. Science has partially identified some various methods to minimize grinding wheel loading, however, as to loading of metal-bond diamond grinding wheels the search is still in progress. Therefore, research people have to state, that in spite of the fact that the wheels made of cubic boron nitride are of little use as applied to ceramic, ultrahard, hard-alloyed hard-to-machine and nano-materials of the time, but manufactures have to apply cubic boron nitride wheels wherein diamond ones preferable

Application of protective coatings in combined electric diamond grinding

The article discusses the practical use of combined electro-discharge diamond grinding characterized by metal bond grinding wheel operation in a self-sharpening mode with minimal wheel consumption. The upgrading of grinding equipment technological capabilities at processing high-strength materials is possible due to the galvanic deposition of anti-friction and anti-corrosion films on the surfaces of the diamond wheel and the workpiece. These conditions facilitate the cutting process thereby increasing performance and the quality of the processed surfaces of machine parts. The application of this method provides the diamond wheels operation in self-sharpening mode and guarantees the continuity of its geometric shape which in turn ensures that no defective layer is formed on the treated surface and the cutting tools have longer efficient life

Application of protective coatings in combined electric diamond grinding

The article discusses the practical use of combined electro-discharge diamond grinding characterized by metal bond grinding wheel operation in a self-sharpening mode with minimal wheel consumption. The upgrading of grinding equipment technological capabilities at processing high-strength materials is possible due to the galvanic deposition of anti-friction and anti-corrosion films on the surfaces of the diamond wheel and the workpiece. These conditions facilitate the cutting process thereby increasing performance and the quality of the processed surfaces of machine parts. The application of this method provides the diamond wheels operation in self-sharpening mode and guarantees the continuity of its geometric shape which in turn ensures that no defective layer is formed on the treated surface and the cutting tools have longer efficient life

Adhesive wear mechanism under combined electric diamond grinding

The article provides a scientific substantiation of loading of metal-bond diamond grinding wheels and describes the mechanism of contact interaction (interlocking) of wheels with tool steel as well as its general properties having an influence on combined electric diamond grinding efficiency. The study concluded that a loaded layer can be formed in a few stages different by nature. It is known, that one of the causes of grinding degradation is a continuous loading of active grits (abrasive grinding tool) by workpiece chips. It all affects the diamond grinding wheels efficiency and grinding ability with a result in increase of tool pressure, contact temperature and wheels specific removal rate. Science has partially identified some various methods to minimize grinding wheel loading, however, as to loading of metal-bond diamond grinding wheels the search is still in progress. Therefore, research people have to state, that in spite of the fact that the wheels made of cubic boron nitride are of little use as applied to ceramic, ultrahard, hard-alloyed hard-to-machine and nano-materials of the time, but manufactures have to apply cubic boron nitride wheels wherein diamond ones preferable