Dr. Shibaji Banerjee - Academia.edu (original) (raw)
Papers by Dr. Shibaji Banerjee
arXiv: Cosmology and Nongalactic Astrophysics, 2019
This has been suggested that the dwarf satellite galaxies in the Milky Way may contain substantia... more This has been suggested that the dwarf satellite galaxies in the Milky Way may contain substantial amount of dark matter in them. These dark matters may undergo self-annihilation to produce gamma\gammagamma-rays. The satellite borne gamma\gammagamma-rays telescope such as Fermi-LAT reported the detection of gamma\gammagamma-rays from around 45 Dwarf Spheroidals (dSphs) of Milky Way. In this work, we consider a particle dark matter model and after studying its phenomenology, we calculate the gamma\gammagamma-ray fluxes of each of these 45 dSphs and compare our results with the upper bounds of mass vs annihilation cross-sections of dark matter provided by the Fermi-LAT collaboration. We calculate these fluxes by considering different dark matter density profiles and make a comparison of the results. We also repeat our analysis with another dark matter candidate namely Kaluza-Klein dark matter inspired by extra-dimensional models. We make a critical comparison between the results obtained for each of these models vis...
arXiv (Cornell University), Apr 13, 2023
Cornell University - arXiv, Feb 19, 2019
The gravitational waves (GWs) has been a topic of interest for its versatile capabilities of prob... more The gravitational waves (GWs) has been a topic of interest for its versatile capabilities of probing several aspects of cosmology and early Universe. Gravitational lensing enhances further the extent of this sort of waves and upgrade our understanding to a next level. Besides several similarities with optical waves, GWs are capable of passing through optically opaque celestial objects like stars, exoplanets unlike light waves and manifest a different kind of lensing effect. In this work we have explored the lensing action of compact objects on gravitational waves using numerical means. After modeling the internal mass distribution of the compact objects by TOV equations and tracing wavefronts using geodesic equations, we have found that the GWs are indeed lensed in a manner analogous to the optical lensing of light in presence of a thick optical lens by producing spherical aberration in the focused waves. The distance to the best focused point shows significant dependence with the mass and radius of the lensing star and unlike gravitational lensing, the region inside and outside compact objects responds differently to the incoming waves.
Physical Review D, 2021
The redshifted 21cm radio signal has emerged as an important probe for investigating the dynamics... more The redshifted 21cm radio signal has emerged as an important probe for investigating the dynamics of the dark age Universe (recombination to reionization). In the current analysis, we explore the combined effect of primordial black hole (PBH) evaporation and the baryon-dark matter (DM) interaction in the 21cm scenario. The variation of brightness temperature shows remarkable dependence on the DM masses (m χ) and the baryon-DM cross-sections (σ 0) besides the influences of the PBH parameters (mass M BH and initial mass fraction β BH). We address both upper and lower bounds on β BH for a wide range of PBH mass in presence of different m χ and σ 0 by incorporating the observational excess −500 +200 −500 mK of EDGES's experimental results. Finally, we address similar limits in the m χ-σ 0 parameter plane for different PBH masses.
Monthly Notices of the Royal Astronomical Society, 2003
The existence of compact gravitational lenses, with masses around 0.5 M , has been reported in th... more The existence of compact gravitational lenses, with masses around 0.5 M , has been reported in the halo of the Milky Way. The nature of these dark lenses is as yet obscure, particularly because these objects have masses well above the threshold for nuclear fusion. In this work, we show that they find a natural explanation as being the evolutionary product of the metastable false vacuum domains (the so-called strange quark nuggets) formed in a first order cosmic quark-hadron transition.
Springer Proceedings in Physics, 2020
Recent astrophysical observations indicate that the universe is composed of a large amount of dar... more Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters.
arXiv: General Relativity and Quantum Cosmology, 2018
Gravitational waves from binary black hole pairs have emerged as an important observational tool ... more Gravitational waves from binary black hole pairs have emerged as an important observational tool in current times. The energy of the BH - BH binary pair is radiated in the form of gravitational waves and to compensate for that energy, kinetic energy of the system decreases gradually. Consequently the mutual separation of the objects decreases with time and tends to merge. The whole process may require a very long time comparable or longer than the age of the universe, specially in the case of low mass mergers. We have examined the case in which a massive object compared to the individual masses comprising the binary pair is present nearby such a system. We have found that in this case the merging process takes place much rapidly than that of the conventional BH-BH merging process. Scenarios with both an Intermediate Mass Black Hole (IBMH) ($10^{5}\:M_{\odot}$) as well as a Super Massive Black Hole (SMBH) have been studied and the latter has been found to provide a much higher overal...
arXiv: Cosmology and Nongalactic Astrophysics, 2020
We study the fluctuations in the brightness temperature of 21-cm signal deltaT21\delta T_{21}deltaT21 focused a... more We study the fluctuations in the brightness temperature of 21-cm signal deltaT21\delta T_{21}deltaT21 focused at the dark age ($z\sim100$) with dark matter candidate in IDM model for the two cases where (1) the dark matter (DM) relic densities Omegac\Omega_{c}Omegac lie within the 9595\%95 confidence limit of the relic density Omegac,0\Omega_{c,0}Omegac,0 obtained from the Planck experiment and (2) the values of Omegac\Omega_{c}Omegac are not comparable with Omegac,0\Omega_{c,0}Omegac,0. We consider both the DM annihilation and the DM-baryon elastic scattering as the combined additional effect on deltaT21\delta T_{21}deltaT21 in the presence of thermal evolution. We find the absorption spectra of deltaT21\delta T_{21}deltaT21 for the case (1) whereas we see the emission spectra of deltaT21\delta T_{21}deltaT21 for the case (2). This imposes a lower bound on the DM annihilation cross-sections which lie in the range 6.5times10−29,,rmcm3/secleqlanglesigmavrangleleq4.88times10−26,,rmcm3/sec6.5 \times 10^{-29} \,\, \rm{cm^ 3 / sec} \leq \langle\sigma v\rangle \leq 4.88\times 10^{-26}\,\, \rm{cm^ 3 / sec}6.5times10−29,,rmcm3/secleqlanglesigmavrangleleq4.88times10−26,,rmcm3/sec for the DM mass range $10 \, {\rm GeV} \leq M_{\chi}\leq ...
Monthly Notices of the Royal Astronomical Society
The mass-to-luminosity ratio of the dwarf satellite galaxies in the Milky Way suggests that these... more The mass-to-luminosity ratio of the dwarf satellite galaxies in the Milky Way suggests that these dwarf galaxies may contain substantial dark matter. The dark matter at the dense region such as within or at the vicinity of the centres of these dwarf galaxies may undergo the process of self-annihilation and produce γ-rays as the end product. The satellite borne γ-ray telescope such as Fermi-LAT reported the detection of γ-rays from around 45 Dwarf Spheroidals (dSphs) of Milky Way. In this work, we consider particle dark matter models described in the literature and after studying their phenomenologies, we calculate the γ-ray fluxes from the self-annihilation of the dark matter within the framework of these models in case of each of these 45 dSphs. We then compare the computed results with the observational upper bounds for γ-ray flux reported by Fermi-LAT and Dark Energy Survey for each of the 45 dSphs. The fluxes are calculated by adopting different dark matter density profiles. We ...
Recent astrophysical observations indicate that the universe is composed of a large amount of dar... more Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters.
arXiv: High Energy Astrophysical Phenomena, 2014
The present work is connected with the investigation of the origin and properties of compact astr... more The present work is connected with the investigation of the origin and properties of compact astrophysical objects endowed with strangeness, with the objective of finding out their relevance in the formation and evolution of the universe. In the first part of the thesis, Chap.~1-3, we discuss a model, proposed by us, to describe the propagation of small lumps of Strange Quark Matter (SQM) or strangelets, through the Terrestrial atmosphere. The theoretical results were found to be well correlated with exotic cosmic ray events characterized by very low charge to mass ratio. In the next part, we have investigated the other end of the mass spectrum of SQM. In Chap 5, we have developed an analytical expression for the Chandrasekhar Limit of Strange Quark Stars. The limit is found to depend on the fundamental constants (including the bag constant). In the last chapter we have endeavored to show that the quark nuggets, surviving the quark-hadron phase transition in the millisecond era of t...
Physics Letters B, 2005
Recent astrophysical observations indicate that the universe is composed of a large amount of dar... more Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters.
International Journal of Modern Physics A
We study the fluctuations in the brightness temperature of 21-cm signal [Formula: see text] at th... more We study the fluctuations in the brightness temperature of 21-cm signal [Formula: see text] at the dark ages ([Formula: see text]) with a dark matter (DM) candidate in Inert Doublet Model (IDM). We then explore the effects of different fractions of IDM DM on [Formula: see text] signal. The IDM DM masses are chosen in few tens of GeV region as well as in the high mass region beyond 500 GeV. It has been observed that the [Formula: see text] signal is more sensitive in the DM mass range of 70–80 GeV. A lower bound on annihilation cross-section for this DM is also obtained by analyzing the [Formula: see text] signal. This is found to lie within the range [Formula: see text] cm3/s for the IDM DM mass range 10 GeV[Formula: see text] GeV.
Physical Review C
The limiting mass is a significant characteristic for compact exotic stars. In the case of quark ... more The limiting mass is a significant characteristic for compact exotic stars. In the case of quark stars the limiting mass can be expressed in terms of fundamental constants and the bag constant. In the present paper, using bag model description, the maximum mass of a rotating quark star is found to depend on the rotational frequency apart from other fundamental parameters. The analytical results obtained agree with the results of several relevant numerical estimates as well as observational evidences.
Physics Letters B
Considering that the ultrahigh energy (UHE) upgoing muon neutrino events around the PeV energy re... more Considering that the ultrahigh energy (UHE) upgoing muon neutrino events around the PeV energy region observed by the IceCube are due to the decay of super heavy dark matter to neutrinos, we constrain the mass of the decaying dark matter and its decay lifetime using the IceCube analysis of these neutrinos in the PeV region. The theoretical fluxes are computed by adpoting the procedure given in the reference [1, 2], where the DGLAP numerical evolutions of QCD cascades as well as electroweak corrections are included for evolving the decay process of the super heavy dark matter. Our results indicate that to explain the IceCube events around PeV region the decaying dark matter mass m χ would be ∼ 5 × 10 7 GeV with the decay lifetime τ ∼ 7 × 10 28 sec.
In the next part, we have investigated the other end of the mass spectrum of SQM. In Chap 5, we h... more In the next part, we have investigated the other end of the mass spectrum of SQM. In Chap 5, we have developed an analytical expression for the Chandrasekhar Limit of Strange Quark Stars. The limit is found to depend on the fundamental constants (including the bag constant). In the last chapter we have endeavored to show that the quark nuggets, surviving the quark-hadron phase transition in the millisecond era of the early Universe can provide the required closure density and can merge to form compact quark matter objects, whose maximum mass would be governed by the formulation laid out in the preceding chapter. We have also found that these Cold Dark Matter objects can explain the recent astronomical observations of MACHOS by gravitational micro-lensing techniques in the Large Magellanic clouds in the Halo of our Galaxy.
Pramana, 2003
A first-order quark hadron phase transition in the early Universe may lead to the formation of qu... more A first-order quark hadron phase transition in the early Universe may lead to the formation of quark nuggets. The baryon number distribution of these quark nuggets have been calculated and it has been found that there are sizeable number of quark nuggets in the stable sector. The nuggets can clump and form bigger objects in the mass range of 0 0003M ¬ to 0 12M ¬. It has been discussed that these bigger objects can be possible candidates for cold dark matter.
Physics Letters B, 2005
Recent astrophysical observations indicate that the universe is composed of a large amount of dar... more Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters.
Physical Review Letters, 2000
The mechanism for the propagation of strangelets with low baryon number through the atmosphere of... more The mechanism for the propagation of strangelets with low baryon number through the atmosphere of the Earth has been explored. It has been shown that, under suitable initial conditions, such strangelets may indeed reach depths near mountain altitudes with mass numbers and charges close to the observed values in cosmic ray experiments.
arXiv: Cosmology and Nongalactic Astrophysics, 2019
This has been suggested that the dwarf satellite galaxies in the Milky Way may contain substantia... more This has been suggested that the dwarf satellite galaxies in the Milky Way may contain substantial amount of dark matter in them. These dark matters may undergo self-annihilation to produce gamma\gammagamma-rays. The satellite borne gamma\gammagamma-rays telescope such as Fermi-LAT reported the detection of gamma\gammagamma-rays from around 45 Dwarf Spheroidals (dSphs) of Milky Way. In this work, we consider a particle dark matter model and after studying its phenomenology, we calculate the gamma\gammagamma-ray fluxes of each of these 45 dSphs and compare our results with the upper bounds of mass vs annihilation cross-sections of dark matter provided by the Fermi-LAT collaboration. We calculate these fluxes by considering different dark matter density profiles and make a comparison of the results. We also repeat our analysis with another dark matter candidate namely Kaluza-Klein dark matter inspired by extra-dimensional models. We make a critical comparison between the results obtained for each of these models vis...
arXiv (Cornell University), Apr 13, 2023
Cornell University - arXiv, Feb 19, 2019
The gravitational waves (GWs) has been a topic of interest for its versatile capabilities of prob... more The gravitational waves (GWs) has been a topic of interest for its versatile capabilities of probing several aspects of cosmology and early Universe. Gravitational lensing enhances further the extent of this sort of waves and upgrade our understanding to a next level. Besides several similarities with optical waves, GWs are capable of passing through optically opaque celestial objects like stars, exoplanets unlike light waves and manifest a different kind of lensing effect. In this work we have explored the lensing action of compact objects on gravitational waves using numerical means. After modeling the internal mass distribution of the compact objects by TOV equations and tracing wavefronts using geodesic equations, we have found that the GWs are indeed lensed in a manner analogous to the optical lensing of light in presence of a thick optical lens by producing spherical aberration in the focused waves. The distance to the best focused point shows significant dependence with the mass and radius of the lensing star and unlike gravitational lensing, the region inside and outside compact objects responds differently to the incoming waves.
Physical Review D, 2021
The redshifted 21cm radio signal has emerged as an important probe for investigating the dynamics... more The redshifted 21cm radio signal has emerged as an important probe for investigating the dynamics of the dark age Universe (recombination to reionization). In the current analysis, we explore the combined effect of primordial black hole (PBH) evaporation and the baryon-dark matter (DM) interaction in the 21cm scenario. The variation of brightness temperature shows remarkable dependence on the DM masses (m χ) and the baryon-DM cross-sections (σ 0) besides the influences of the PBH parameters (mass M BH and initial mass fraction β BH). We address both upper and lower bounds on β BH for a wide range of PBH mass in presence of different m χ and σ 0 by incorporating the observational excess −500 +200 −500 mK of EDGES's experimental results. Finally, we address similar limits in the m χ-σ 0 parameter plane for different PBH masses.
Monthly Notices of the Royal Astronomical Society, 2003
The existence of compact gravitational lenses, with masses around 0.5 M , has been reported in th... more The existence of compact gravitational lenses, with masses around 0.5 M , has been reported in the halo of the Milky Way. The nature of these dark lenses is as yet obscure, particularly because these objects have masses well above the threshold for nuclear fusion. In this work, we show that they find a natural explanation as being the evolutionary product of the metastable false vacuum domains (the so-called strange quark nuggets) formed in a first order cosmic quark-hadron transition.
Springer Proceedings in Physics, 2020
Recent astrophysical observations indicate that the universe is composed of a large amount of dar... more Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters.
arXiv: General Relativity and Quantum Cosmology, 2018
Gravitational waves from binary black hole pairs have emerged as an important observational tool ... more Gravitational waves from binary black hole pairs have emerged as an important observational tool in current times. The energy of the BH - BH binary pair is radiated in the form of gravitational waves and to compensate for that energy, kinetic energy of the system decreases gradually. Consequently the mutual separation of the objects decreases with time and tends to merge. The whole process may require a very long time comparable or longer than the age of the universe, specially in the case of low mass mergers. We have examined the case in which a massive object compared to the individual masses comprising the binary pair is present nearby such a system. We have found that in this case the merging process takes place much rapidly than that of the conventional BH-BH merging process. Scenarios with both an Intermediate Mass Black Hole (IBMH) ($10^{5}\:M_{\odot}$) as well as a Super Massive Black Hole (SMBH) have been studied and the latter has been found to provide a much higher overal...
arXiv: Cosmology and Nongalactic Astrophysics, 2020
We study the fluctuations in the brightness temperature of 21-cm signal deltaT21\delta T_{21}deltaT21 focused a... more We study the fluctuations in the brightness temperature of 21-cm signal deltaT21\delta T_{21}deltaT21 focused at the dark age ($z\sim100$) with dark matter candidate in IDM model for the two cases where (1) the dark matter (DM) relic densities Omegac\Omega_{c}Omegac lie within the 9595\%95 confidence limit of the relic density Omegac,0\Omega_{c,0}Omegac,0 obtained from the Planck experiment and (2) the values of Omegac\Omega_{c}Omegac are not comparable with Omegac,0\Omega_{c,0}Omegac,0. We consider both the DM annihilation and the DM-baryon elastic scattering as the combined additional effect on deltaT21\delta T_{21}deltaT21 in the presence of thermal evolution. We find the absorption spectra of deltaT21\delta T_{21}deltaT21 for the case (1) whereas we see the emission spectra of deltaT21\delta T_{21}deltaT21 for the case (2). This imposes a lower bound on the DM annihilation cross-sections which lie in the range 6.5times10−29,,rmcm3/secleqlanglesigmavrangleleq4.88times10−26,,rmcm3/sec6.5 \times 10^{-29} \,\, \rm{cm^ 3 / sec} \leq \langle\sigma v\rangle \leq 4.88\times 10^{-26}\,\, \rm{cm^ 3 / sec}6.5times10−29,,rmcm3/secleqlanglesigmavrangleleq4.88times10−26,,rmcm3/sec for the DM mass range $10 \, {\rm GeV} \leq M_{\chi}\leq ...
Monthly Notices of the Royal Astronomical Society
The mass-to-luminosity ratio of the dwarf satellite galaxies in the Milky Way suggests that these... more The mass-to-luminosity ratio of the dwarf satellite galaxies in the Milky Way suggests that these dwarf galaxies may contain substantial dark matter. The dark matter at the dense region such as within or at the vicinity of the centres of these dwarf galaxies may undergo the process of self-annihilation and produce γ-rays as the end product. The satellite borne γ-ray telescope such as Fermi-LAT reported the detection of γ-rays from around 45 Dwarf Spheroidals (dSphs) of Milky Way. In this work, we consider particle dark matter models described in the literature and after studying their phenomenologies, we calculate the γ-ray fluxes from the self-annihilation of the dark matter within the framework of these models in case of each of these 45 dSphs. We then compare the computed results with the observational upper bounds for γ-ray flux reported by Fermi-LAT and Dark Energy Survey for each of the 45 dSphs. The fluxes are calculated by adopting different dark matter density profiles. We ...
Recent astrophysical observations indicate that the universe is composed of a large amount of dar... more Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters.
arXiv: High Energy Astrophysical Phenomena, 2014
The present work is connected with the investigation of the origin and properties of compact astr... more The present work is connected with the investigation of the origin and properties of compact astrophysical objects endowed with strangeness, with the objective of finding out their relevance in the formation and evolution of the universe. In the first part of the thesis, Chap.~1-3, we discuss a model, proposed by us, to describe the propagation of small lumps of Strange Quark Matter (SQM) or strangelets, through the Terrestrial atmosphere. The theoretical results were found to be well correlated with exotic cosmic ray events characterized by very low charge to mass ratio. In the next part, we have investigated the other end of the mass spectrum of SQM. In Chap 5, we have developed an analytical expression for the Chandrasekhar Limit of Strange Quark Stars. The limit is found to depend on the fundamental constants (including the bag constant). In the last chapter we have endeavored to show that the quark nuggets, surviving the quark-hadron phase transition in the millisecond era of t...
Physics Letters B, 2005
Recent astrophysical observations indicate that the universe is composed of a large amount of dar... more Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters.
International Journal of Modern Physics A
We study the fluctuations in the brightness temperature of 21-cm signal [Formula: see text] at th... more We study the fluctuations in the brightness temperature of 21-cm signal [Formula: see text] at the dark ages ([Formula: see text]) with a dark matter (DM) candidate in Inert Doublet Model (IDM). We then explore the effects of different fractions of IDM DM on [Formula: see text] signal. The IDM DM masses are chosen in few tens of GeV region as well as in the high mass region beyond 500 GeV. It has been observed that the [Formula: see text] signal is more sensitive in the DM mass range of 70–80 GeV. A lower bound on annihilation cross-section for this DM is also obtained by analyzing the [Formula: see text] signal. This is found to lie within the range [Formula: see text] cm3/s for the IDM DM mass range 10 GeV[Formula: see text] GeV.
Physical Review C
The limiting mass is a significant characteristic for compact exotic stars. In the case of quark ... more The limiting mass is a significant characteristic for compact exotic stars. In the case of quark stars the limiting mass can be expressed in terms of fundamental constants and the bag constant. In the present paper, using bag model description, the maximum mass of a rotating quark star is found to depend on the rotational frequency apart from other fundamental parameters. The analytical results obtained agree with the results of several relevant numerical estimates as well as observational evidences.
Physics Letters B
Considering that the ultrahigh energy (UHE) upgoing muon neutrino events around the PeV energy re... more Considering that the ultrahigh energy (UHE) upgoing muon neutrino events around the PeV energy region observed by the IceCube are due to the decay of super heavy dark matter to neutrinos, we constrain the mass of the decaying dark matter and its decay lifetime using the IceCube analysis of these neutrinos in the PeV region. The theoretical fluxes are computed by adpoting the procedure given in the reference [1, 2], where the DGLAP numerical evolutions of QCD cascades as well as electroweak corrections are included for evolving the decay process of the super heavy dark matter. Our results indicate that to explain the IceCube events around PeV region the decaying dark matter mass m χ would be ∼ 5 × 10 7 GeV with the decay lifetime τ ∼ 7 × 10 28 sec.
In the next part, we have investigated the other end of the mass spectrum of SQM. In Chap 5, we h... more In the next part, we have investigated the other end of the mass spectrum of SQM. In Chap 5, we have developed an analytical expression for the Chandrasekhar Limit of Strange Quark Stars. The limit is found to depend on the fundamental constants (including the bag constant). In the last chapter we have endeavored to show that the quark nuggets, surviving the quark-hadron phase transition in the millisecond era of the early Universe can provide the required closure density and can merge to form compact quark matter objects, whose maximum mass would be governed by the formulation laid out in the preceding chapter. We have also found that these Cold Dark Matter objects can explain the recent astronomical observations of MACHOS by gravitational micro-lensing techniques in the Large Magellanic clouds in the Halo of our Galaxy.
Pramana, 2003
A first-order quark hadron phase transition in the early Universe may lead to the formation of qu... more A first-order quark hadron phase transition in the early Universe may lead to the formation of quark nuggets. The baryon number distribution of these quark nuggets have been calculated and it has been found that there are sizeable number of quark nuggets in the stable sector. The nuggets can clump and form bigger objects in the mass range of 0 0003M ¬ to 0 12M ¬. It has been discussed that these bigger objects can be possible candidates for cold dark matter.
Physics Letters B, 2005
Recent astrophysical observations indicate that the universe is composed of a large amount of dar... more Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters.
Physical Review Letters, 2000
The mechanism for the propagation of strangelets with low baryon number through the atmosphere of... more The mechanism for the propagation of strangelets with low baryon number through the atmosphere of the Earth has been explored. It has been shown that, under suitable initial conditions, such strangelets may indeed reach depths near mountain altitudes with mass numbers and charges close to the observed values in cosmic ray experiments.