Doubly nonlocal system with Hardy-Littlewood-Sobolev critical nonlinearity

This article concerns about the existence and multiplicity of weak solutions for the following nonlinear doubly nonlocal problem with critical nonlinearity in the sense of Hardy-Littlewood-Sobolev inequality \begin{equation*} \left\{ \begin{split} (-\Delta)^su &= \lambda |u|^{q-2}u + \left(\int_{\Omega}\frac{|v(y)|^{2^*_\mu}}{|x-y|^\mu}~\mathrm{d}y\right) |u|^{2^*_\mu-2}u\; \text{in}\; \Omega (-\Delta)^sv &= \delta |v|^{q-2}v + \left(\int_{\Om}\frac{|u(y)|^{2^*_\mu}}{|x-y|^\mu}~\mathrm{d}y \right) |v|^{2^*_\mu-2}v \; \text{in}\; \Omega u &=v=0\; \text{in}\; \mb R^n\setminus\Omega, \end{split} \right. \end{equation*} where $\Omega$ is a smooth bounded domain in \mb R^n, $n >2s$, $s \in (0,1)$, $(-\Delta)^s$ is the well known fractional Laplacian, $\mu \in (0,n)$, $2^*_\mu = \displaystyle\frac{2n-\mu}{n-2s}$ is the upper critical exponent in the Hardy-Littlewood-Sobolev inequality, $1<q<2$ and $\lambda,\delta >0$ are real parameters. We study the fibering maps corresponding to the functional associated with $(P_{\lambda,\delta})$ and show that minimization over suitable subsets of Nehari manifold renders the existence of atleast two non trivial solutions of (P_{\la,\delta}) for suitable range of \la and $\delta$.Comment: 37 page

A Global multiplicity result for a very singular critical nonlocal equation

In this article, we show the global multiplicity result for the following nonlocal singular problem \begin{equation*} (P_\la):\;\quad (-\De)^s u = u^{-q} + \la u^{{2^*_s}-1}, \quad u>0 \; \text{in}\; \Om,\quad u = 0 \; \mbox{in}\; \mb R^n \setminus\Om, \end{equation*} where \Om is a bounded domain in \mb{R}^n with smooth boundary \partial \Om, n > 2s,\; s \in (0,1),\; \la >0,\; q>0 satisfies $q(2s-1)<(2s+1)$ and $2^*_s=\frac{2n}{n-2s}$. Employing the variational method, we show the existence of at least two distinct weak positive solutions for (P_\la) in $X_0$ when \la \in (0,\La) and no solution when \la>\La, where \La>0 is appropriately chosen. We also prove a result of independent interest that any weak solution to $(P_\lambda)$ is in $C^\alpha(\R^n)$ with $\alpha=\alpha(s,q)\in (0,1)$. The asymptotic behaviour of weak solutions reveals that this result is sharp.Comment: 23 page

Positive solution branch for elliptic problems with critical indefinite nonlinearity

In this paper, we study the semilinear elliptic problem with critical nonlinearity and an indefinite weight function, namely -Δu=λu+h(x)un+2/n-2 in a smooth domain bounded (respectively, unbounded) Ω⊆Rn, n&gt;4, for λ≥0. Under suitable assumptions on the weight function, we obtain the positive solution branch, bifurcating from the first eigenvalue λ1(Ω) (respectively, the bottom of the essential spectrum)

H\"older regularity results for parabolic nonlocal double phase problems

In this article, we obtain higher H\"older regularity results for weak solutions to nonlocal problems driven by the fractional double phase operator \begin{align*} \mc L u(x):=&2 \; {\rm P.V.} \int_{\mathbb R^N} \frac{|u(x)-u(y)|^{p-2}(u(x)-u(y))}{|x-y|^{N+ps_1}}dy \nonumber &+2 \; {\rm P.V.} \int_{\mathbb R^N} a(x,y) \frac{|u(x)-u(y)|^{q-2}(u(x)-u(y))}{|x-y|^{N+qs_2}}dy, \end{align*} where $1<p\leq q<\infty$, $0<s_2, s_1<1$ and the modulating coefficient $a(\cdot,\cdot)$ is a non-negative bounded function. Specifically, we prove higher space-time H\"older continuity result for weak solutions of time depending nonlocal double phase problems for a particular subclass of the modulating coefficients. Using suitable approximation arguments, we further establish higher (global) H\"older continuity results for weak solutions to the stationary problems involving the operator \mc L with modulating coefficients that are locally continuous

Fractional Hamiltonian type system on R\mathbb{R} with critical growth nonlinearity

This article investigates the existence and properties of ground state solutions to the following nonlocal Hamiltonian elliptic system: \begin{align*} \begin{cases} (-\Delta)^\frac12 u +V_0 u =g(v),~x\in \mathbb{R} (-\Delta)^\frac12 v +V_0 v =f(u),~x\in \mathbb{R}, \end{cases} \end{align*} where $(-\Delta)^\frac12$ is the square root Laplacian operator, $V_0 >0$ and $f,~g$ have critical exponential growth in $\mathbb{R}$. Using minimization technique over some generalized Nehari manifold, we show that the set $\mathcal{S}$ of ground state solutions is non empty. Moreover for $(u,v) \in \mathcal{S}$, $u,~v$ are uniformly bounded in $L^\infty(\mathbb{R})$ and uniformly decaying at infinity. We also show that the set $\mathcal{S}$ is compact in $H^\frac12(\mathbb{R}) \times H^\frac12(\mathbb{R})$ up to translations. Furthermore under locally lipschitz continuity of $f$ and $g$ we obtain a suitable Poho\v{z}aev type identity for any $(u,v) \in \mathcal{S}$. We deduce the existence of semi-classical ground state solutions to the singularly perturbed system \begin{align*} \begin{cases} \epsilon(-\Delta)^\frac12 \varphi +V(x) \varphi =g(\psi),~x\in \mathbb{R} \epsilon (-\Delta)^\frac12 \psi +V(x) \psi =f(\varphi),~x\in \mathbb{R}, \end{cases} \end{align*} where $\epsilon>0$ and $V \in C(\mathbb{R})$ satisfy the assumption $(V)$ given below (see Section 1). Finally as $\epsilon \rightarrow 0$, we prove the existence of minimal energy solutions which concentrate around the closest minima of the potential $V$