We have studied the Earth matter effect on the oscillation of upward going GeV neutrinos by takin... more We have studied the Earth matter effect on the oscillation of upward going GeV neutrinos by taking into account the three active neutrino flavors. For neutrino energy in the range 3 to 12 GeV we observed three distinct resonant peaks for the oscillation process $\nu_e\leftrightarrow \nu_{\mu,\tau}$ in three \textit{distinct} densities. For the calculation of observed flux of these GeV neutrinos, we considered two different flux ratio at the source, the standard scenario with flux ratio $1:2:0$ and the muon damped scenario $0:1:0$. It is observed that while the standard scenario gives the observed flux ratio $1:1:1$, the muon damped scenario has a different ratio. The PINGU will be able to shed more light on the nature of the resonance in these GeV neutrinos.
An individual’s reaction time data to visual stimuli have usually been represented in Experimenta... more An individual’s reaction time data to visual stimuli have usually been represented in Experimental Psychology by means of an ex-Gaussian function. In most previous works, researchers have mainly aimed at finding a meaning for the parameters of the ex-Gaussian function which are known to correlate with cognitive disorders. Based on the recent evidence of correlations between the reaction time series to visual stimuli produced by different individuals within a group, we go beyond and propose a Physics-inspired model to represent the reaction time data of a coetaneous group of individuals. In doing so, a Maxwell–Boltzmann-like distribution appeared, the same distribution as for the velocities of the molecules in an Ideal Gas model. We describe step by step the methodology we use to go from the individual reaction times to the distribution of the individuals response within the coetaneous group. In practical terms, by means of this model we also provide a simple entropy-based methodolog...
232 were analyzed to derive strong upper limits on the EBL, which were found to be consistent wit... more 232 were analyzed to derive strong upper limits on the EBL, which were found to be consistent with the lower limits from the integrated light of resolved galaxies. Here we have used the photohadronic model corroborated by two template EBL models to fit the observed VHE gamma-ray data from these two HBLs and to predict their intrinsic spectra. We obtain very good fit to the VHE spectra of these two HBLs. However, the predicted intrinsic spectra are different for each EBL model. For the HBL H 2356-309, we obtain a flat intrinsic spectrum and for 1ES 1101-232 the spectrum is mildly harder than 2 but much softer than 1.5.
The detection of GRB 180722B and GRB 190114C in sub-TeV gamma-rays has opened up a new window to ... more The detection of GRB 180722B and GRB 190114C in sub-TeV gamma-rays has opened up a new window to study gamma-ray bursts in high energy gamma-rays. Recently it is shown that the synchrotron and inverse Compton processes are responsible for the production of these high energy gamma-rays during the afterglow. Here, for the first time we demonstrate that, the photohadronic scenario which is successful in explaining the multi-TeV flaring in high energy blazars is also applicable for gamma-ray bursts. We show that the sub-TeV spectra of GRB 190114C and GRB 180720B are due to the interaction of high energy protons with the background photons in the synchrotron self-Compton region and synchrotron region respectively. The nature of the background photon distributions help us to constraint their bulk Lorentz factors.
The detection of multi-TeV gamma rays from the afterglow phase of GRB 190829A by the High Energy ... more The detection of multi-TeV gamma rays from the afterglow phase of GRB 190829A by the High Energy Stereoscopic System telescope is an addition to the already existing list of two GRBs observed in very high-energy (VHE) gamma rays in recent years. Jets of blazars and GRBs have many similarities and the photohadronic model is very successful in explaining the VHE gamma-ray spectra from the high-energy blazars. Recently, the photohadronic model has been successfully applied to study the sub-TeV gamma rays from the afterglow phases of GRB 180720B and GRB 190114C. We employed this model again to explain the VHE spectra observed for the two consecutive nights from GRB 190829A. We show that the spectra of GRB 190829A can be due to the interactions of high-energy protons with the synchrotron self-Compton photons in the forward shock region of the GRB jet, similar to the low emission state of the VHE flaring events of high-energy blazars. We speculate that, if in the future, it is possible to...
The momentum projected SU(3) Chiral Color Dielectric Model (CCDM) is employed to calculate the ch... more The momentum projected SU(3) Chiral Color Dielectric Model (CCDM) is employed to calculate the charge root mean square radii and charge distributions of hyperons. We compare our result with Skyrme, MIT bag and Cloudy Bag model results. The charge distribution of Λ in CCDM is similar to that of Skyrme Model prediction.
Proceedings of International Europhysics Conference on High Energy Physics — PoS(HEP2005), Apr 24, 2007
Interaction of ultra-energetic cosmic neutrinos with a thermal gas of relic neutrinos Véronique V... more Interaction of ultra-energetic cosmic neutrinos with a thermal gas of relic neutrinos Véronique Van Elewyck
ABSTRACT Centaurus A has been one of the best studied radio galaxies, observed in radio, infrared... more ABSTRACT Centaurus A has been one of the best studied radio galaxies, observed in radio, infrared, X-ray and gamma-ray. Cen A has been associated with two cosmic ray events with energies about 57 EeV by the Pierre Auger Observatory. By assuming the first peak in the continuous spectra comes from electron synchrotron emission and that the second peak comes from self-synchrotron Compton (SSC), we show that pp interaction could be responsible for the TeV emission and that the obtained cosmic ray rate is in agreement with Pierre Auger Observations.
We use the Feynman path integral approach to nonrelativistic quantum mechanics twofold. First, we... more We use the Feynman path integral approach to nonrelativistic quantum mechanics twofold. First, we derive the lagrangian for a spinless particle moving in a uniformly but not necessarily constantly accelerated reference frame; then, applying the strong equivalence principle (SEP) we obtain the Schroedinger equation for a particle in an inertial frame and in the presence of a uniform and constant gravity field. Second, using the associated Feynman propagator, we propagate an initial gaussian wave packet, with the final wave function and probability density depending on the ratio m , where m is the inertial mass of the particle, thus exhibiting the fact that the weak equivalence principle (WEP) is violated by quantum mechanics. Although due to rapid oscillations the wave function does not exist in the classical limit, the probability density is well defined and mass independent when → 0, showing the recovery of the WEP. Finally, at the quantum level, a heavier particle does not necessarily falls faster than a lighter one; this depends on the relations between the initial and final common positions and times of the particles.
Centaurus A is the nearest radio-loud AGN and is detected from radio to very high energy gamma-ra... more Centaurus A is the nearest radio-loud AGN and is detected from radio to very high energy gamma-rays. Its nuclear spectral energy distribution shows two peaks, one in the far-infrared band and another at about 150 keV. By assuming the second peak is due to the electron synchrotron emission and the power index for the differential spectrum of the very high energy cosmic ray proton to be 2.7 we show that only pp interaction is responsible for the observed GeV-TeV emission from Centaurus A. We also found that indeed many very high energy cosmic ray protons from Centaurus A can arrive on Earth thus supporting the recent observation of two events by Pierre Auger Observatory.
Mohanty and Samal have shown that the magnetic-moment interaction with nucleons contributes signi... more Mohanty and Samal have shown that the magnetic-moment interaction with nucleons contributes significantly to the photon dispersion relation in a supernova core, and with an opposite sign relative to the usual plasma effect. Because of a numerical error they overestimated the magnetic-moment term by two orders of magnitude, but it is still of the same order as the plasma effect. It appears that the Cherenkov processes γν → ν and ν → νγ remain forbidden, but a final verdict depends on a more detailed investigation of the dynamical magnetic susceptibility of a hot nuclear medium.
We evaluate the matrix element ofqq in hadron states on a lattice. We find substantial mixing of ... more We evaluate the matrix element ofqq in hadron states on a lattice. We find substantial mixing of the connected and disconnected contributions so that the lattice result that the disconnected contribution to the nucleon is large does not imply that thess content is large. This has implications for dark matter searches.
The color dielectric model is used to study the static properties of the SU(3) baryon octet and d... more The color dielectric model is used to study the static properties of the SU(3) baryon octet and decuplet using the dielectric functional X(x) = xs with p = 2 and 4 and where the gluon contribution is treated perturbatively. We found that for the two-phase solutions with a large quark mass and glueball mass-1.7 GeV, the static properties fit the observed values reasonably well. But in this range the strange-quark mass and strong-coupling constant are large compared to other models. It is also observed that for both cases the results are similar although p = 2 is more favorable than p=4.
We have studied the Earth matter effect on the oscillation of upward going GeV neutrinos by takin... more We have studied the Earth matter effect on the oscillation of upward going GeV neutrinos by taking into account the three active neutrino flavors. For neutrino energy in the range 3 to 12 GeV we observed three distinct resonant peaks for the oscillation process $\nu_e\leftrightarrow \nu_{\mu,\tau}$ in three \textit{distinct} densities. For the calculation of observed flux of these GeV neutrinos, we considered two different flux ratio at the source, the standard scenario with flux ratio $1:2:0$ and the muon damped scenario $0:1:0$. It is observed that while the standard scenario gives the observed flux ratio $1:1:1$, the muon damped scenario has a different ratio. The PINGU will be able to shed more light on the nature of the resonance in these GeV neutrinos.
An individual’s reaction time data to visual stimuli have usually been represented in Experimenta... more An individual’s reaction time data to visual stimuli have usually been represented in Experimental Psychology by means of an ex-Gaussian function. In most previous works, researchers have mainly aimed at finding a meaning for the parameters of the ex-Gaussian function which are known to correlate with cognitive disorders. Based on the recent evidence of correlations between the reaction time series to visual stimuli produced by different individuals within a group, we go beyond and propose a Physics-inspired model to represent the reaction time data of a coetaneous group of individuals. In doing so, a Maxwell–Boltzmann-like distribution appeared, the same distribution as for the velocities of the molecules in an Ideal Gas model. We describe step by step the methodology we use to go from the individual reaction times to the distribution of the individuals response within the coetaneous group. In practical terms, by means of this model we also provide a simple entropy-based methodolog...
232 were analyzed to derive strong upper limits on the EBL, which were found to be consistent wit... more 232 were analyzed to derive strong upper limits on the EBL, which were found to be consistent with the lower limits from the integrated light of resolved galaxies. Here we have used the photohadronic model corroborated by two template EBL models to fit the observed VHE gamma-ray data from these two HBLs and to predict their intrinsic spectra. We obtain very good fit to the VHE spectra of these two HBLs. However, the predicted intrinsic spectra are different for each EBL model. For the HBL H 2356-309, we obtain a flat intrinsic spectrum and for 1ES 1101-232 the spectrum is mildly harder than 2 but much softer than 1.5.
The detection of GRB 180722B and GRB 190114C in sub-TeV gamma-rays has opened up a new window to ... more The detection of GRB 180722B and GRB 190114C in sub-TeV gamma-rays has opened up a new window to study gamma-ray bursts in high energy gamma-rays. Recently it is shown that the synchrotron and inverse Compton processes are responsible for the production of these high energy gamma-rays during the afterglow. Here, for the first time we demonstrate that, the photohadronic scenario which is successful in explaining the multi-TeV flaring in high energy blazars is also applicable for gamma-ray bursts. We show that the sub-TeV spectra of GRB 190114C and GRB 180720B are due to the interaction of high energy protons with the background photons in the synchrotron self-Compton region and synchrotron region respectively. The nature of the background photon distributions help us to constraint their bulk Lorentz factors.
The detection of multi-TeV gamma rays from the afterglow phase of GRB 190829A by the High Energy ... more The detection of multi-TeV gamma rays from the afterglow phase of GRB 190829A by the High Energy Stereoscopic System telescope is an addition to the already existing list of two GRBs observed in very high-energy (VHE) gamma rays in recent years. Jets of blazars and GRBs have many similarities and the photohadronic model is very successful in explaining the VHE gamma-ray spectra from the high-energy blazars. Recently, the photohadronic model has been successfully applied to study the sub-TeV gamma rays from the afterglow phases of GRB 180720B and GRB 190114C. We employed this model again to explain the VHE spectra observed for the two consecutive nights from GRB 190829A. We show that the spectra of GRB 190829A can be due to the interactions of high-energy protons with the synchrotron self-Compton photons in the forward shock region of the GRB jet, similar to the low emission state of the VHE flaring events of high-energy blazars. We speculate that, if in the future, it is possible to...
The momentum projected SU(3) Chiral Color Dielectric Model (CCDM) is employed to calculate the ch... more The momentum projected SU(3) Chiral Color Dielectric Model (CCDM) is employed to calculate the charge root mean square radii and charge distributions of hyperons. We compare our result with Skyrme, MIT bag and Cloudy Bag model results. The charge distribution of Λ in CCDM is similar to that of Skyrme Model prediction.
Proceedings of International Europhysics Conference on High Energy Physics — PoS(HEP2005), Apr 24, 2007
Interaction of ultra-energetic cosmic neutrinos with a thermal gas of relic neutrinos Véronique V... more Interaction of ultra-energetic cosmic neutrinos with a thermal gas of relic neutrinos Véronique Van Elewyck
ABSTRACT Centaurus A has been one of the best studied radio galaxies, observed in radio, infrared... more ABSTRACT Centaurus A has been one of the best studied radio galaxies, observed in radio, infrared, X-ray and gamma-ray. Cen A has been associated with two cosmic ray events with energies about 57 EeV by the Pierre Auger Observatory. By assuming the first peak in the continuous spectra comes from electron synchrotron emission and that the second peak comes from self-synchrotron Compton (SSC), we show that pp interaction could be responsible for the TeV emission and that the obtained cosmic ray rate is in agreement with Pierre Auger Observations.
We use the Feynman path integral approach to nonrelativistic quantum mechanics twofold. First, we... more We use the Feynman path integral approach to nonrelativistic quantum mechanics twofold. First, we derive the lagrangian for a spinless particle moving in a uniformly but not necessarily constantly accelerated reference frame; then, applying the strong equivalence principle (SEP) we obtain the Schroedinger equation for a particle in an inertial frame and in the presence of a uniform and constant gravity field. Second, using the associated Feynman propagator, we propagate an initial gaussian wave packet, with the final wave function and probability density depending on the ratio m , where m is the inertial mass of the particle, thus exhibiting the fact that the weak equivalence principle (WEP) is violated by quantum mechanics. Although due to rapid oscillations the wave function does not exist in the classical limit, the probability density is well defined and mass independent when → 0, showing the recovery of the WEP. Finally, at the quantum level, a heavier particle does not necessarily falls faster than a lighter one; this depends on the relations between the initial and final common positions and times of the particles.
Centaurus A is the nearest radio-loud AGN and is detected from radio to very high energy gamma-ra... more Centaurus A is the nearest radio-loud AGN and is detected from radio to very high energy gamma-rays. Its nuclear spectral energy distribution shows two peaks, one in the far-infrared band and another at about 150 keV. By assuming the second peak is due to the electron synchrotron emission and the power index for the differential spectrum of the very high energy cosmic ray proton to be 2.7 we show that only pp interaction is responsible for the observed GeV-TeV emission from Centaurus A. We also found that indeed many very high energy cosmic ray protons from Centaurus A can arrive on Earth thus supporting the recent observation of two events by Pierre Auger Observatory.
Mohanty and Samal have shown that the magnetic-moment interaction with nucleons contributes signi... more Mohanty and Samal have shown that the magnetic-moment interaction with nucleons contributes significantly to the photon dispersion relation in a supernova core, and with an opposite sign relative to the usual plasma effect. Because of a numerical error they overestimated the magnetic-moment term by two orders of magnitude, but it is still of the same order as the plasma effect. It appears that the Cherenkov processes γν → ν and ν → νγ remain forbidden, but a final verdict depends on a more detailed investigation of the dynamical magnetic susceptibility of a hot nuclear medium.
We evaluate the matrix element ofqq in hadron states on a lattice. We find substantial mixing of ... more We evaluate the matrix element ofqq in hadron states on a lattice. We find substantial mixing of the connected and disconnected contributions so that the lattice result that the disconnected contribution to the nucleon is large does not imply that thess content is large. This has implications for dark matter searches.
The color dielectric model is used to study the static properties of the SU(3) baryon octet and d... more The color dielectric model is used to study the static properties of the SU(3) baryon octet and decuplet using the dielectric functional X(x) = xs with p = 2 and 4 and where the gluon contribution is treated perturbatively. We found that for the two-phase solutions with a large quark mass and glueball mass-1.7 GeV, the static properties fit the observed values reasonably well. But in this range the strange-quark mass and strong-coupling constant are large compared to other models. It is also observed that for both cases the results are similar although p = 2 is more favorable than p=4.
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Papers by Sarira Sahu