We consider a simple modification of quadratic chaotic inflation. We add a logarithmic correction to the mass term, and find that this model can be consistent with the latest cosmological observations such as the Planck 2018 data, in combination with the BICEP2/Keck Array and the baryon acoustic oscillation data. Since the model predicts the lower limit for the tensor-to-scalar ratio r for the present allowed values of the spectral index n_s, it could be tested by the cosmic microwave background polarization observation in the near future. In addition, we consider higher-order logarithmic corrections. Interestingly, we observe that the scalar spectral index n_s and r stay in rather a narrow region of the parameter space. Moreover, they reside in a completely different region from that for the logarithmic corrections to the quartic coupling. Therefore, future observations may distinguish which kind of corrections should be included, or even single out the form of the interactions.
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