Published online by Cambridge University Press: 17 February 2016
Let ${\rm\Lambda}(n)$ be the von Mangoldt function,
$x$ be real and
$2\leqslant y\leqslant x$ . This paper improves the estimate for the exponential sum over primes in short intervals
$$\begin{eqnarray}S_{k}(x,y;{\it\alpha})=\mathop{\sum }_{x<n\leqslant x+y}{\rm\Lambda}(n)e(n^{k}{\it\alpha})\end{eqnarray}$$
$k\geqslant 3$ for
${\it\alpha}$ in the minor arcs. When combined with the Hardy–Littlewood circle method, this enables us to investigate the Waring–Goldbach problem concerning the representation of a positive integer
$n$ as the sum of
$s$
$k$ th powers of almost equal prime numbers, and improve the results of Wei and Wooley [On sums of powers of almost equal primes. Proc. Lond. Math. Soc. (3) 111(5) (2015), 1130–1162].