$L^1$ means of exponential sums with multiplicative coefficients. II

Mayank Pandey, Maksym Radziwiłł

Let $f$ be a real-valued $1$-bounded multiplicative function. Suppose that the mean-value of $f^2$ exists, and $$\int_{0}^{1} \Big | \sum_{n \leq N} f(n)e^{2πi n α} \Big | d α\le…