\documentstyle{SibMatJ} % \TestXML \topmatter \Author Dimitrov \Initial S. \Initial I. \Gender he \Email sdimitrov\@tu-sofia.bg \Email xyzstoyan\@gmail.com \AffilRef 1 \AffilRef 2 \endAuthor \Affil 1 \Division Faculty of Applied Mathematics and Informatics \Organization Technical University of Sofia \City Sofia \Country Bulgaria \endAffil \Affil 2 \Division Department of Bioinformatics and Mathematical Modelling \Organization Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences \City Sofia \Country Bulgaria \endAffil \datesubmitted December 17, 2025\enddatesubmitted \dateaccepted December 28, 2025\enddateaccepted \UDclass ??? %11D75 11P32 \endUDclass \title Diophantine Approximation with Mixed Powers Of Piatetski-Shapiro Primes \endtitle \abstract Let $[\,\cdot\,]$ denote the floor function. In this paper, we show that whenever $\eta$ is real and the constants $\lambda _i$ satisfy some necessary conditions, then for any fixed $\frac{63}{64}<\gamma<1$ and $\theta>0$, there exist infinitely many prime triples $p_1,\, p_2,\, p_3$ satisfying the inequality $$ %\? |\lambda _1p_1 + \lambda _2p_2 + \lambda _3p^2_3+\eta|<(\max \{p_1, p_2, p^2_3\})^{\frac{63-64\gamma}{52}+\theta} $$ and such that $p_i=[n_i^{1/\gamma}]$, $i=1,2,3$. \endabstract \keywords Diophantine approximation, Piatetski-Shapiro primes \endkeywords \endtopmatter \head 1. Introduction and Statement of the Result \endhead The study of Diophantine inequalities involving prime numbers constitutes a rapidly evolving field within analytic number theory. In 1967, A. Baker %\?просто Baker [1] proved that if $\lambda_1,\lambda_2,\lambda_3$ are nonzero real numbers, not all of the same sign, $\lambda_1/\lambda_2$ is irrational, $\eta$ is real and $A>0$, then there exist infinitely many prime triples $p_1,p_2,p_3$ such that $$ |\lambda_1p_1+\lambda_2p_2+\lambda_3p_3+\eta|<\varepsilon_1, \tag1 $$ where $\varepsilon_1=(\log \max p_j)^{-A}$. Subsequently, the right-hand side of \Tag(1) was improved by Ramachandra [2], Vaughan [3], Lau and Liu [4], Baker and Harman [5], and Harman [6]. The best result to date is due to Matom\"{a}ki [7], with $\varepsilon_1=( \max p_j)^{-\frac{2}{9}+\delta}$ and $\delta>0$. In 2018, Gambini, Languasco, and Zaccagnini [8] proved the existence of infinitely many triples of primes $p_1$, $p_2$, and $p_3$ such that $$ |\lambda_1p_1+\lambda_2p_2+\lambda_3p^2_3+\eta|<\varepsilon_2, \tag2 $$ where $\varepsilon_2=(\max \{p_1, p_2, p^2_3\})^{-\frac{1}{12}+\delta}$ and $\delta>0$. Weaker results were previously obtained in [9] and [10]. Another interesting question is the study of Diophantine inequalities involving special prime numbers. Let $P_l$ is a number with at most $l$ prime factors. Very recently Todorova and Georgieva [11] solved inequality \Tag(2) with prime numbers $p_1$, $p_2$, and $p_3$ such that $p_i+2=P_{l_i}$,\;$i=1,\,2,\,3$. In 1953, Piatetski-Shapiro [12] showed that for any fixed $\frac{11}{12}<\gamma<1$, there exist infinitely many prime numbers of the form $p = [n^{1/\gamma}]$. Such primes are called Piatetski-Shapiro primes %\?{\it Piatetski-Shapiro primes\/} of type $\gamma$. Subsequently, the interval for $\gamma$ was sharpened many times and the best result to date has been supplied by Rivat and Wu [13] with $\frac{205}{243}<\gamma<1$. The primes of the form $[n^{1/\gamma}]$ are very much in focus nowadays and many problems are solved using them. We mention, for example, the papers [14--16]. In 2022, the author [17] %\? proved that for any fixed $\frac{37}{38}<\gamma<1$, inequality \Tag(1) is solvable with infinitely many Piatetski-Shapiro prime triples $p_1$, $p_2$, $p_3$ of type $\gamma$. As a continuation of these studies, we solve \Tag(2) with Piatetski-Shapiro primes. \proclaim{Theorem 1} Suppose that $\lambda_1,\lambda_2,\lambda_3$ are nonzero real numbers, not all of the same sign, that $\lambda_1/\lambda_2$ is irrational, and that $\eta$ is real. Let $\theta>0$ and $\gamma$ be fixed with $\frac{63}{64}<\gamma<1$. Then there exist infinitely many ordered triples of Piatetski-Shapiro primes $p_1$, $p_2$, and $p_3$ of type $\gamma$ such that $$ |\lambda_1p_1+\lambda_2p_2+\lambda_3p^2_3+\eta|<(\max \{p_1, p_2, p^2_3\})^{\frac{63-64\gamma}{52}+\theta}. $$ \endproclaim \head 2. Notations \endhead The letter $p$ will always denote a prime number. By $\delta$ we denote an arbitrarily small positive number, not the same in all appearances. As usual, $[t]$ and $\{t\}$ denote the integer part and the fractional part of~$t$, respectively. Moreover $\psi(t)=\{t\}-\frac{1}{2}$. We write $e(t)=e^{2\pi it}$. Let $\gamma$, $\theta$, and $\lambda_0$ be a %\? real constants such that $\frac{63}{64}<\gamma<1$, $\theta>0$, and $0<\lambda_0<1$. Since $\lambda_1/\lambda_2$ is irrational, there are infinitely many different convergents $a_0/q_0$ to its continued fraction, with $|\frac{\lambda_1}{\lambda_2} - \frac{a_0}{q_0}|<\frac{1}{q_0^2}$, $(a_0, q_0) = 1$, $a_0\neq0$ and $q_0$ is arbitrary large. Denote %\?внести авторскую правку в формулы!!! \iftex $$ \align &X=q_0^\frac{13}{6}; \tag3 \\ &\Delta =X^{-\frac{12}{13}}\log X; \tag4 \\ &\varepsilon =X^{\frac{63-64\gamma}{52}+\theta}; \tag5 \\ &H=\frac{\log^2X}{\varepsilon}; \tag6 \\ &S_k(t)=\sum\limits\Sb\lambda_0X0$ and $k\in \Bbb{N}$. There exists a function $\theta(y)$ which is $k$ times continuously differentiable and such that \iftex $$ \alignat2 &\theta(y)=1&\quad&\text{for }\ |y|\leq 3\varepsilon/4; \\ &0<\theta(y)<1&\quad&\text{for }\ 3\varepsilon/4 <|y|< \varepsilon; \\ &\theta(y)=0&\quad&\text{for }\ |y|\geq \varepsilon, \endalignat $$ \else $$ \align \theta(y)=1\quad &\text{for }\ |y|\leq 3\varepsilon/4; \\ 0<\theta(y)<1\quad &\text{for }\ 3\varepsilon/4 <|y|< \varepsilon; \\ \theta(y)=0\quad &\text{for }\ |y|\geq \varepsilon, \endalign $$ \fi and its Fourier transform $$ \Theta(x)=\int\limits_{-\infty}^{\infty}\theta(y)e(-xy)dy $$ satisfies the inequality $$ |\Theta(x)|\leq\min\Bigl(\frac{7\varepsilon}{4},\frac{1}{\pi|x|},\frac{1}{\pi |x|} \Bigl(\frac{k}{2\pi |x|\varepsilon/8}\Bigr)^k\Bigr). $$ \endproclaim \demo{Proof} See [18]. \qed\enddemo \proclaim{Lemma 2} For any fixed $\frac{2426}{2817}<\gamma<1$, we have $$ \sum\limits\Sb p\leq X\\ p=[n^{1/\gamma}]\endSb 1\sim \frac{X^\gamma}{\log X}. $$ \endproclaim \demo{Proof} See [19, Theorem 1]. \qed\enddemo \proclaim{Lemma 3}\Label{L3} We have \Item (i) $\int\nolimits_{-\Delta}^\Delta|S_1(t)|^2\,dt\ll X\log^3X$ and $\int\nolimits_{0}^1|S_1(t)|^2\,dt\ll X^{2-\gamma}\log X$, \Item (ii) $\int\nolimits_{-\Delta}^\Delta|I_1( t)|^2\,dt\ll X$ and $\int\nolimits_{-\Delta}^\Delta|I_2( t)|^2\,dt\ll 1$. \endproclaim \demo{Proof} For \Par{L3}{(i)} see [17, Lemma 6]. For \Par{L3}{(ii)} see [11, Lemma 15]. \qed\enddemo \proclaim{Lemma 4} Let $|t|\leq\Delta$. Then the asymptotic formula $$ S_1(t)=\gamma I_1(t)+ \Cal{O}\Bigl(\frac{X}{e^{(\log X)^{1/5}}}\Bigr) $$ holds. \endproclaim \demo{Proof} See [17, Lemma 5]. \qed\enddemo \proclaim{Lemma 5} Let $\frac{13}{14}<\gamma<1$. Then $$ \Omega(t)\ll X^{\frac{21-7\gamma}{29}+\delta}\,. $$ \endproclaim \demo{Proof} See [20, Lemma 6]. \qed\enddemo \proclaim{Lemma 6} Let $k\geq1$ and $1/2X\leq Y\leq 1/2X^{1-\frac{5}{6k}+\delta}$. Then there exists a positive constant $c_1(\delta)$, which does not depend on $k$, such that $$ \int\limits_{-Y}^Y|\Sigma(t)-U(t)|^2\,dt\ll\frac{X^{\frac{2}{k}-2}\log^2X}{Y}+Y^2X+X^{\frac{2}{k}-1} \exp\Bigl(-c_1\Bigl(\frac{\log X}{\log\log X}\Bigr)^{1/3}\Bigr). $$ \endproclaim \demo{Proof} See [8, Lemmas 1 and 2]. \qed\enddemo \proclaim{Lemma 7} Let $\frac{11}{12}<\gamma<1$ and $\Delta\leq|t|\leq H$. Then there exists a sequence of real numbers $X_1,X_2,\dots %\? \to \infty $ such that $$ \min\bigl\{|S_1(\lambda_{1}t)|,|S_1(\lambda_2 t)|\bigr\}\ll X_j^{\frac{37-12\gamma}{26}}\log^5X_j, \quad j=1,2,\dots. $$ \endproclaim \demo{Proof} See [17, Lemma 7]. \qed\enddemo \proclaim{Lemma 8} We have $$ \int\limits_{0}^1|S_2(t)|^4\,dt\ll X^{2-\gamma+\delta}\,. $$ \endproclaim \demo{Proof} See [21, (12)]. \qed\enddemo \head 4. Beginning of the Proof \endhead Consider the sum $$ \Gamma(X)=\sum\limits\Sb \lambda_0XH}\Theta(t)S_1(\lambda_1t)S_1(\lambda_1t)S_2(\lambda_3t)e(\eta t)\,dt. \tag16 \endalign $$ \else $$ \Gamma_1(X)=\int\limits_{|t|<\Delta}\Theta(t)S_1(\lambda_1t)S_1(\lambda_2t)S_2(\lambda_3t)e(\eta t)\,dt, \tag14 $$ $$ \Gamma_2(X)=\int\limits_{\Delta\leq|t|\leq H}\Theta(t)S_1(\lambda_1t)S_1(\lambda_2t)S_2(\lambda_3t)e(\eta t)\,dt, \tag15 $$ $$ \Gamma_3(X)=\int\limits_{|t|>H}\Theta(t)S_1(\lambda_1t)S_1(\lambda_1t)S_2(\lambda_3t)e(\eta t)\,dt. \tag16 $$ \fi We will estimate $\Gamma_1(X)$, $\Gamma_2(X)$, and $\Gamma_3(X)$, respectively, in \Sec{Section 5}{Sections 5}--\Sec{Section 7}{7}. In \Sec*{Section 8} we will complete the proof of \Par*{Theorem 1}. \head 5. Lower Bound of $\Gamma_1(X)$ \endhead \proclaim{Lemma 9} Let $\frac{13}{14}<\gamma<1$. Then $$ S_2(t)=\gamma\Sigma(t)+\Cal{O}(X^{\frac{21-7\gamma}{29}+\delta}). $$ \endproclaim \demo{Proof} From \Tag(7), \Tag(8), \Tag(10), and the well-known asymptotic formula $$ (p+1)^\gamma-p^\gamma=\gamma p^{\gamma-1}+\Cal{O}(p^{\gamma-2}) $$ we write $$ \aligned S_2(t) &=\sum\limits_{\lambda_0X