Studies towards the possible temporal variation of the fine structure constant

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dc.contributor.advisor Sahoo, Bijaya Kumar
dc.contributor.author Nandy, Dillip Kumar
dc.date.accessioned 2016-06-16T12:32:08Z
dc.date.available 2016-06-16T12:32:08Z
dc.date.issued 2015
dc.identifier.citation Nandy, Dillip Kumar (2015). Studies towards the possible temporal variation of the fine structure constant (PhD. Dissertations). Indian Institute of Technology, Gandhinagar, pp. 183 (Acc No: T00107) en_US
dc.identifier.uri https://repository.iitgn.ac.in/handle/123456789/2333
dc.description.abstract In the standard model (SM) of particle physics it is a well-known fact that coupling constants of different fundamental interactions run with energy. The variations of these coupling constants under different local energy regimes have already been verified experimentally. But in the current scenario there is no law or symmetry principle, other than a presumption for the sake of simplicity, that restrains the physical constants of nature from varying in space and time. Hence, it is necessary to verify this assumption experimentally. Investigations of temporal variation of fundamental constants have been gaining the ground steadily in both the theoretical and experimental physics for the last two decades [J. P. Uzan, Rev. Mod. Phys. 75, 403 (2003), J. A. King, et al. MNRAS 422, 3370 (2012), H. Chand, et al., Precision Spectroscopy in Astrophysics]. Important consequences of searching for searching such variations are to establish theories suggesting violation of Einstein's equivalence principle, to support unification of gravity with the other three fundamental interactions of nature [T. Damour, et al., Phys. Rev. D 89, 081601 (2002), T. Damour, et al., Phys. Rev. D 66, 046007 (2002), T. Kaluza, Sitzungber. Press. Akad. Wiss. Phys. Math. Kl. L IV, 966 (1921), O. Klein, Z. Phys. 37, 895 (1926), A. Chodos and S. Detweiler, Phys. Rev. D 21, 2167 (1980), W. J. Marciano, Phys. Rev. Lett. 52], et cetera. This will also probe the multidimensionality to space as predicted by super-string theories [T. Damour and A. M. Polyakov, Nucl. Phys. B 423, 532 (1994)]. These theories predict temporal variations of dimensionless fundamental constants including the electromagnetic fine structure constant (αe = e2 ~c ) in the low energy limit at the cosmological time-scale. The primary objective of this thesis is to provide accurate results for the relativistic sensitivity coefficients which can be further used to investigate temporal variation of αe. We have employed relativistic coupled-cluster (RCC) methods developed by us to determine these sensitivity coefficients in many astrophysically relevant atomic systems and also for some of the atomic clock transitions to study the possible temporal variation of αe. It can be perceived that the anticipated relativistic e are quite large in the highly charged ions, and seem to be the promising candidates for such investigation. So we have considered many possible highly charged ions and investigated enhancement of relativistic e in these systems. To give more accurate results for the sensitivity coefficients, we also estimate the contributions from the Breit interaction and the dominating quantum electrodynamic (QED) corrections in addition to the contribution from Dirac-Coulomb (DC) Hamiltonian. For the above purpose, we have developed one-electron detachment and one-electron attachment RCC methods from a closed-shell atomic configurations. Using the above methods, we determine the sensitivity coefficients (or q-values) for three low-lying 3s23p5 2P3=2 ! 3s3p6 2S1=2, 3s23p5 2P3=2 ! 3s3p6 2S1=2 and 3s23p5 2P3=2 ! 3s23p5 2P1=2 transitions in the Cl-like Mn IX, Fe X, Co XI and Ni XII ions. We also calculate the sensitivity coefficients for the three lowlying transitions 2s22p5 2P3=2 ! 2s2p6 2S1=2, 2s22p5 2P3=2 ! 2s2p6 2S1=2 and 2s22p5 2P3=2 ! 2s22p5 2P1=2 in the F-like Ti XIV, V XV, Cr XVI, Mn XVII, Fe XVIII, Co XIX, Ni XX, Cu XXI, Zn XXII and Mo XXXIV ions very accurately. In addition to these ions, we have also calculated the sensitivity coefficients for a number of astrophysically relevant transitions in the Si IV, Ti IV and Zn II ions using our RCC methods. Since Si IV, Ti IV and Zn II ions are highly abundant in many quasars, we have provided q-values for a number of important transitions in these ions to achieve better statistical analysis in the estimation of αe variation using the Many-Multiplet (MM) method. We also carry out very accurate calculations of some of the physical quantities which are vital in the precise estimate of absolute frequencies in the atomic clock experiments. One of them is the quadrupole shift in the Yb+ ion clock which arises due to the interaction of electric field gradient with the quadrupole moment of the atomic systems. We have investigated quadrupole shifts for three prominent clock transitions, [4f146s]2S1=2 ! [4f145d]2D3=2, [4f146s]2S1=2 ! [4f145d]2D5=2 and [4f146s]2S1=2 ! [4f136s2]2F7=2, in the Yb+ ion by calculating quadrupole moments ((-)s) of the [4f145d]2D3=2;5=2 and [4f136s2]2F7=2 states using our methods. We find an order of magnitude difference in the (-) value of the [4f136s2]2F7=2 state between our calculation and the experimental result, but our result concur with the other two calculations that are carried out using different many-body methods than ours. However, our (-) value of the [4f145d]2D3=2 state is in good agreement with the available available experimental results, and is the most precise estimate of the quadrupole shift The other calculated systematic is the black-body radiation (BBR) shifts due to the magnetic dipole (M1) and electric quadrupole (E2) components of the radiation fields in the Ca+ and Sr+ single ion clocks. We have estimated contribution from the M1 and E2 multipoles of the radiation fields for the 4s 2S1=2 ! 3d 2D5=2 and 5s 2S1=2 ! 4d 2D5=2 transitions in the singly ionized calcium and strontium, respectively. These shifts are obtained by calculating the corresponding multipolar scalar polarizabilities of the involved atomic states. Precise estimate of these systematics are quite important for determining uncertainties to the measured clock frequencies in these ions, which are further used for giving stringent bound on the temporal variation in αe. en_US
dc.language.iso en_US en_US
dc.publisher Indian Institute of Technology, Gandhinagar en_US
dc.subject Fine structure constant en_US
dc.subject Sensitivity coefficient en_US
dc.subject Alkali-Doublet method en_US
dc.subject Many-Multiple method en_US
dc.subject Atomic clock en_US
dc.subject Dirac-Fock model en_US
dc.subject Hyperfine interaction en_US
dc.subject Quadrupole shifts en_US
dc.subject Black-body radiation shifts en_US
dc.subject Many-body perturbation theory en_US
dc.subject Relativistic coupled-cluster method en_US
dc.subject One-electron detachment method en_US
dc.subject One-electron attachment method en_US
dc.subject Ionization potential energies en_US
dc.subject Electron affinities en_US
dc.title Studies towards the possible temporal variation of the fine structure constant en_US
dc.type Thesis en_US
dc.contributor.department Physics.
dc.description.degree Ph.D.


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