This thesis investigates the effect of radiative corrections on spontaneous symmetry breaking in quantum field theories. Using a functional formalism, the author shows that spontaneous symmetry breaking can occur even when the classical approximation suggests a symmetric vacuum. This is particularly evident in massless gauge theories with scalar mesons, where quantum corrections induce symmetry breaking, leading to a relationship between scalar and vector meson masses. The analysis is extended to models where the classical approximation predicts an asymmetric vacuum, including cases where the vacuum's nature is not fully determined by the classical approximation. Renormalization group methods are employed to improve the analysis, allowing for a more accurate description of the vacuum's properties. The thesis begins with an introduction to spontaneous symmetry breaking in particle physics, highlighting its role in explaining the masses of pions and weak intermediate vector mesons. It then presents a formalism based on functional methods, which allows for the calculation of the effective potential, incorporating both explicit and quantum corrections. The effective potential is shown to determine the vacuum state of the theory, with its minima corresponding to the ground state. The author applies this formalism to a simple model of a single quartically self-coupled scalar field, demonstrating that spontaneous symmetry breaking can occur even when the classical approximation suggests a symmetric vacuum. The effective potential is calculated, revealing a logarithmic singularity and a potential minimum at a non-zero vacuum expectation value. However, the validity of this result is questioned due to the presence of infrared divergences and the need for higher-order calculations. The thesis then extends the analysis to more complex models, including those with multiple fields and gauge symmetries. The effective potential is calculated for these models, showing how the presence of different particles and interactions affects the vacuum structure. The author also discusses the renormalization of coupling constants and wave function renormalization, highlighting the importance of logarithmic singularities and the need for renormalization at non-zero momentum values. The study concludes with a discussion of the implications of spontaneous symmetry breaking in various models, emphasizing the role of quantum corrections in determining the vacuum's properties. The author notes that while the one-loop approximation may not be sufficient to determine spontaneous symmetry breaking, higher-order calculations and the use of renormalization group methods can provide a more accurate description. The thesis underscores the importance of considering quantum corrections in understanding the vacuum structure of quantum field theories.This thesis investigates the effect of radiative corrections on spontaneous symmetry breaking in quantum field theories. Using a functional formalism, the author shows that spontaneous symmetry breaking can occur even when the classical approximation suggests a symmetric vacuum. This is particularly evident in massless gauge theories with scalar mesons, where quantum corrections induce symmetry breaking, leading to a relationship between scalar and vector meson masses. The analysis is extended to models where the classical approximation predicts an asymmetric vacuum, including cases where the vacuum's nature is not fully determined by the classical approximation. Renormalization group methods are employed to improve the analysis, allowing for a more accurate description of the vacuum's properties. The thesis begins with an introduction to spontaneous symmetry breaking in particle physics, highlighting its role in explaining the masses of pions and weak intermediate vector mesons. It then presents a formalism based on functional methods, which allows for the calculation of the effective potential, incorporating both explicit and quantum corrections. The effective potential is shown to determine the vacuum state of the theory, with its minima corresponding to the ground state. The author applies this formalism to a simple model of a single quartically self-coupled scalar field, demonstrating that spontaneous symmetry breaking can occur even when the classical approximation suggests a symmetric vacuum. The effective potential is calculated, revealing a logarithmic singularity and a potential minimum at a non-zero vacuum expectation value. However, the validity of this result is questioned due to the presence of infrared divergences and the need for higher-order calculations. The thesis then extends the analysis to more complex models, including those with multiple fields and gauge symmetries. The effective potential is calculated for these models, showing how the presence of different particles and interactions affects the vacuum structure. The author also discusses the renormalization of coupling constants and wave function renormalization, highlighting the importance of logarithmic singularities and the need for renormalization at non-zero momentum values. The study concludes with a discussion of the implications of spontaneous symmetry breaking in various models, emphasizing the role of quantum corrections in determining the vacuum's properties. The author notes that while the one-loop approximation may not be sufficient to determine spontaneous symmetry breaking, higher-order calculations and the use of renormalization group methods can provide a more accurate description. The thesis underscores the importance of considering quantum corrections in understanding the vacuum structure of quantum field theories.