It is entirely plausible that during the primordial quark–hadron phase transition, microseconds after the Big Bang, the universe may experience supercooling accompanied by mini inflation leading to a ...first-order phase transition from quarks to hadrons. The relics, in the form of quark nuggets, with baryon number beyond a critical value will survive the evolution of the universe. The quark nuggets are candidates of strange quark matter. It is conjectured that colour confinement turns the physical vacuum to an event horizon for quarks and gluons. The horizon can be crossed only by quantum tunnelling. The process just mentioned is the QCD counterpart of Hawking radiation from gravitational black holes. Tunnelling of neutrons from the nuggets is equivalent to Hawking radiation from the gravitational black hole. Thus, when the Hawking temperature of the quark nuggets gets turned off, tunnelling will stop and the nuggets will survive forever. The baryon number and the mass of these nuggets are derived using this theoretical format. The results agree well with the prediction using other phenomenological models. Further, the variation of Hawking temperature as a function of baryon number and mass of the nugget mimics chiral phase transition, somewhat similar to the QCD phase transition. Finally, the strange quark nuggets may well be the candidates of baryonic dark matter.
Borehole sonic tools with an array of receivers provide estimates of plane wave velocities and dispersion characteristics associated with guided modes across receiver apertures ranging from 0.6 to ...1.8 m. In addition, borehole resistivity imaging tools can be used to determine thin lamination thicknesses of about 5-10-cm interbedded in a reservoir. Recently, ultrasonic tools have been demonstrated to measure compressional and shear velocities across thin laminations using transit time of corresponding refracted headwaves along the borehole surface. However, mass densities of laminations cannot be determined from transit times of headwaves. Inversion of borehole flexural or Stoneley-guided mode dispersions yields three effective alteration parameters that include elastic stiffnesses and mass densities of laminations. These parameters are defined in terms of fractional changes in the Lamé constants and mass density of the laminate from those of a reference homogeneous formation weighted by the ratio of laminate and formation thicknesses probed by the propagating wave. Since the laminate thickness is estimated from a borehole resistivity imaging tool, and formation thickness probed is determined from the sonic tool receiver aperture, ratios of the laminate to formation thicknesses are known inputs to the inversion workflow. Consequently, changes in the two Lamé constants and mass density of the laminate can be estimated from those in the reference formation. Estimates of the compressional and shear moduli together with the mass density of laminate provide a complete elastic characterization that are of value in estimating compressional and shear impedances of the laminate.
This article describes a novel technique to estimate static Young's modulus of stress-sensitive rocks using dynamic linear and nonlinear constants estimated from borehole sonic data. Two linear and ...three nonlinear constants are estimated from the transit time of compressional headwaves and inversion of borehole-guided Stoneley and crossdipole dispersions in tectonically stressed formations. A major advantage of this technique is that the rock static Young's modulus is determined from the dynamic elastic constants measured at a chosen reference state that is rather close to the in situ conditions. These dynamic elastic constants are used in the nonlinear constitutive relations for poroelastic rocks subject to finite deformations. These relations express the second Piola-Kirchhoff axial stresses in terms of elastic constants together with up to quadratic terms in Lagrangian axial strains. Strain derivatives of the second Piola-Kirchhoff stress yield the static Young's modulus as a function of incremental axial strains from a chosen reference state. Consequently, static Young's modulus can also be determined at other depths with different overburden stresses and associated incremental axial strains from a chosen reference state. In contrast, strain derivative of the second Piola-Kirchhoff axial stress expressed in terms of linear elastic constants and only linear terms in axial strain provides the dynamic Young's modulus. Two useful outputs from this workflow are the static stress-strain deformation curves for a core plug and static Young's modulus under in situ conditions as a function of logging depth. The proposed technique has been validated with the available experimental stress-strain data from Castlegate and Berea sandstones core plugs. Results have been obtained for the static Young's modulus and finite deformation stress-strain curves for two different stress-sensitive poroelastic formations using borehole sonic data.
Exploration wells are liquid-filled boreholes drilled into formations with different geophysical and petrophysical properties. These boreholes support axisymmetric, flexural, and quadrupole family of ...guided modes that can probe radially varying formation properties at different frequencies. Radially varying formation properties are caused by drilling-induced fractures or near-wellbore stress concentrations. This work describes a novel workflow that inverts borehole flexural and Stoneley dispersions to obtain radially varying formation mass density and shear and bulk moduli away from the borehole surface. An integral equation relates fractional changes in guided mode velocities at different frequencies caused by fractional changes in radially varying mass density and shear and bulk moduli from a radially uniform reference state. A solution of this integral equation is based on extending the Backus-Gilbert (B-G) method for obtaining radial profile of a single to radial profiles of three formation properties away from the borehole surface. Inverted radial profiles from synthetic flexural and Stoneley dispersions have been validated against input formation parameters used to generate synthetic (measured) dispersions.
It is entirely plausible that during the primordial quark-hadron phase transition, microseconds after the big bang, the Universe may experience supercooling accompanied by mini inflation leading to a ...first-order phase transition from quarks to hadrons. The relics, in the form of quark nuggets, with baryon number beyond a critical value will survive the evolution of the Universe. The quark nuggets are candidates of strange quark matter. It is conjectured that color confinement turns the physical vacuum to an event horizon for quarks and gluons. The horizon can be crossed only by quantum tunneling. The process just mentioned is the QCD counterpart of Hawking radiation from gravitational black holes. Tunneling of neutrons from the nuggets is equivalent to Hawking radiation from the gravitational black hole. Thus, when the Hawking temperature of the quark nuggets gets turned off, tunneling will stop and the nuggets will survive forever. The baryon number and the mass of these nuggets are derived using this theoretical format. The results agree well with the prediction using other phenomenological models. Further, the variation of Hawking temperature as a function of baryon number and mass of the nugget mimics chiral phase transition, somewhat similar to the QCD phase transition. Finally, the strange quark nuggets may well be the candidates of baryonic dark matter.
The Cosmic Quarks Sinha, Bikash
Nuclear physics. A,
February 2019, 2019-02-00, Letnik:
982
Journal Article
Recenzirano
Odprti dostop
Quark nuggets, relics of a first order phase transition, from quarks to hadrons, microseconds after the big bang; the core of the neutron star, and the colour entangled quarks, prior to the phase ...transition, are possible candidates of the cosmic quarks.
This paper describes an exhaustive study of the variations of the mean force sensitivity coefficients in the entire region of crystalline langasite (LGS). We also study the variation of temperature ...coefficients in the entire region of the crystalline LGS and its isomorphs. The computational results have been obtained from a procedure that has been successfully employed in the study of the planar and temperature stress-induced frequency shifts in thickness-mode resonators. Both the fast and slow thickness-shear modes have been studied. Among other things, the loci of orientations with zero stress and temperature coefficients of frequency have been identified for LGS.
222Rn concentrations were measured in the bubble gases, spring waters, soil gases and in ambient air around the thermal springs at Bakreswar in West Bengal, India. This group of springs lies within a ...geothermal zone having exceptionally high heat flow about 230 mW/m
2, resembling young oceanic ridges. The spring gas has a high radon activity (∼885 kBq/m
3) and is rich in helium (∼1.4 vol. %) with appreciably large flow rate. The measured radon exhalation rates in the soils of the spring area show extensive variations from 831 to 4550/mBqm
2
h while
222Rn concentrations in the different spring waters vary from 3.18 to 46.9 kBq/m
3. Surface air at a radius of 40
m around the springs, within which is situated the Bakreswar temple complex and a group of dwellings, has radon concentration between 450 and 500
Bq/m
3. In the present paper we assess the radon activity background in and around the spring area due to the different contributing sources and its possible effect on visiting pilgrims and the people who reside close to the springs.
It is entirely plausible that during the primordial quark- hadron phase transition in the universe, microseconds after the Big Bang, supercooling takes place, accompanied by miniinflation. With µ T ∼ ...1 (µ is chemical potential), leading to a first order phase transition from quarks to hadrons; there will be relics in the form of quark nuggets, and, that they consist of Strange Quark Matter. The possibility that these SQM nuggets may well be the candidates of cold dark matter is critically examined. A cursory comparison with the neutron star is presented at the end.
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