<p>Let <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="41" /> </InlineMediaObject> <EquationSource Format="TEX">\(d\geqslant 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>d</mi> <mo>⩾</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>. In this paper, we investigate the following stochastic differential equation (SDE) in <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq2.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="20" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\mathbb {R}}}^d\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mi>d</mi> </msup> </math></EquationSource> </InlineEquation> driven by Brownian motion <Equation ID="Equ125"> <MediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_Equ125.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="195" /> </MediaObject> <EquationSource Format="TEX">\( \textrm{d} X_t=b(t,X_t)\textrm{d} t+\sqrt{2}\textrm{d} W_t, \)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtext>d</mtext> <msub> <mi>X</mi> <mi>t</mi> </msub> <mo>=</mo> <mi>b</mi> <mrow> <mo stretchy="false">(</mo> <mi>t</mi> <mo>,</mo> <msub> <mi>X</mi> <mi>t</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mtext>d</mtext> <mi>t</mi> <mo>+</mo> <msqrt> <mn>2</mn> </msqrt> <mtext>d</mtext> <msub> <mi>W</mi> <mi>t</mi> </msub> <mo>,</mo> </mrow> </math></EquationSource> </Equation>where <i>b</i> belongs to the space <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq3.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\mathbb {L}}}_T^q \textbf{H}_p^\alpha \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mi mathvariant="double-struck">L</mi> <mi>T</mi> <mi>q</mi> </msubsup> <msubsup> <mi mathvariant="bold">H</mi> <mi>p</mi> <mi>α</mi> </msubsup> </mrow> </math></EquationSource> </InlineEquation> with <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq4.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="79" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha \in [-1, 0]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo>∈</mo> <mo stretchy="false">[</mo> <mo>-</mo> <mn>1</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">]</mo> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq5.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="89" /> </InlineMediaObject> <EquationSource Format="TEX">\(p,q\in [2, \infty ]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mo>,</mo> <mi>q</mi> <mo>∈</mo> <mo stretchy="false">[</mo> <mn>2</mn> <mo>,</mo> <mi>∞</mi> <mo stretchy="false">]</mo> </mrow> </math></EquationSource> </InlineEquation>, which is a distribution-valued and divergence-free vector field. In the subcritical case <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq6.gif" Format="GIF" Height="25" Rendition="HTML" Resolution="72" Type="Linedraw" Width="102" /> </InlineMediaObject> <EquationSource Format="TEX">\(\frac{d}{p}+\frac{2}{q}&lt;1+\alpha \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mfrac> <mi>d</mi> <mi>p</mi> </mfrac> <mo>+</mo> <mfrac> <mn>2</mn> <mi>q</mi> </mfrac> <mo>&lt;</mo> <mn>1</mn> <mo>+</mo> <mi>α</mi> </mrow> </math></EquationSource> </InlineEquation>, we establish the existence and uniqueness of a weak solution to the integral equation: <Equation ID="Equ126"> <MediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_Equ126.gif" Format="GIF" Height="44" Rendition="HTML" Resolution="72" Type="Linedraw" Width="289" /> </MediaObject> <EquationSource Format="TEX">\( X_t=X_0+\lim _{n\rightarrow \infty }\int ^t_0b_n(s,X_s)\textrm{d} s+\sqrt{2} W_t. \)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <msub> <mi>X</mi> <mi>t</mi> </msub> <mo>=</mo> <msub> <mi>X</mi> <mn>0</mn> </msub> <mo>+</mo> <munder> <mo movablelimits="true">lim</mo> <mrow> <mi>n</mi> <mo stretchy="false">→</mo> <mi>∞</mi> </mrow> </munder> <msubsup> <mo>∫</mo> <mn>0</mn> <mi>t</mi> </msubsup> <msub> <mi>b</mi> <mi>n</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>s</mi> <mo>,</mo> <msub> <mi>X</mi> <mi>s</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mtext>d</mtext> <mi>s</mi> <mo>+</mo> <msqrt> <mn>2</mn> </msqrt> <msub> <mi>W</mi> <mi>t</mi> </msub> <mo>.</mo> </mrow> </math></EquationSource> </Equation>Here, <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq7.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="84" /> </InlineMediaObject> <EquationSource Format="TEX">\(b_n:=b*\phi _n\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>b</mi> <mi>n</mi> </msub> <mo>:</mo> <mo>=</mo> <mi>b</mi> <mrow /> <mo>∗</mo> <msub> <mi>ϕ</mi> <mi>n</mi> </msub> </mrow> </math></EquationSource> </InlineEquation> represents the mollifying approximation, and the limit is taken in the <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq8.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(L^2\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>L</mi> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>-sense. In the critical and supercritical case <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq9.gif" Format="GIF" Height="25" Rendition="HTML" Resolution="72" Type="Linedraw" Width="163" /> </InlineMediaObject> <EquationSource Format="TEX">\(1+\alpha \leqslant \frac{d}{p}+\frac{2}{q}&lt;2+\alpha \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1</mn> <mo>+</mo> <mi>α</mi> <mo>⩽</mo> <mfrac> <mi>d</mi> <mi>p</mi> </mfrac> <mo>+</mo> <mfrac> <mn>2</mn> <mi>q</mi> </mfrac> <mo>&lt;</mo> <mn>2</mn> <mo>+</mo> <mi>α</mi> </mrow> </math></EquationSource> </InlineEquation>, assuming the initial distribution has an <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq8.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(L^2\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>L</mi> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>-density, we show the existence of weak solutions and associated Markov processes. Moreover, under the additional assumption that <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq11.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="131" /> </InlineMediaObject> <EquationSource Format="TEX">\(b=b_1+b_2+\mathord {\textrm{div}}a\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>b</mi> <mo>=</mo> <msub> <mi>b</mi> <mn>1</mn> </msub> <mo>+</mo> <msub> <mi>b</mi> <mn>2</mn> </msub> <mo>+</mo> <mtext>div</mtext> <mi>a</mi> </mrow> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq12.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="93" /> </InlineMediaObject> <EquationSource Format="TEX">\(b_1\in {{\mathbb {L}}}^\infty _T{{\textbf{B}}}^{-1}_{\infty ,2}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>b</mi> <mn>1</mn> </msub> <mo>∈</mo> <msubsup> <mrow> <mi mathvariant="double-struck">L</mi> </mrow> <mi>T</mi> <mi>∞</mi> </msubsup> <msubsup> <mrow> <mi mathvariant="bold">B</mi> </mrow> <mrow> <mi>∞</mi> <mo>,</mo> <mn>2</mn> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="220_2025_5430_Article_IEq13.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="72" /> </InlineMediaObject> <EquationSource Format="TEX">\(b_2\in {{\mathbb {L}}}^2_TL^2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>b</mi> <mn>2</mn> </msub> <mo>∈</mo> <msubsup> <mrow> <mi mathvariant="double-struck">L</mi> </mrow> <mi>T</mi> <mn>2</mn> </msubsup> <msup> <mi>L</mi> <mn>2</mn> </msup> </mrow> </math></EquationSource> </InlineEquation>, and <i>a</i> is a bounded antisymmetric matrix-valued function, we establish the convergence of mollifying approximation solutions without the need to subtract a subsequence. To illustrate our results, we provide examples of Gaussian random fields and singular interacting particle systems, including the two-dimensional vortex models.</p>

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SDEs with Supercritical Distributional Drifts

  • Zimo Hao,
  • Xicheng Zhang

摘要

Let \(d\geqslant 2\) d 2 . In this paper, we investigate the following stochastic differential equation (SDE) in \({{\mathbb {R}}}^d\) R d driven by Brownian motion \( \textrm{d} X_t=b(t,X_t)\textrm{d} t+\sqrt{2}\textrm{d} W_t, \) d X t = b ( t , X t ) d t + 2 d W t , where b belongs to the space \({{\mathbb {L}}}_T^q \textbf{H}_p^\alpha \) L T q H p α with \(\alpha \in [-1, 0]\) α [ - 1 , 0 ] and \(p,q\in [2, \infty ]\) p , q [ 2 , ] , which is a distribution-valued and divergence-free vector field. In the subcritical case \(\frac{d}{p}+\frac{2}{q}<1+\alpha \) d p + 2 q < 1 + α , we establish the existence and uniqueness of a weak solution to the integral equation: \( X_t=X_0+\lim _{n\rightarrow \infty }\int ^t_0b_n(s,X_s)\textrm{d} s+\sqrt{2} W_t. \) X t = X 0 + lim n 0 t b n ( s , X s ) d s + 2 W t . Here, \(b_n:=b*\phi _n\) b n : = b ϕ n represents the mollifying approximation, and the limit is taken in the \(L^2\) L 2 -sense. In the critical and supercritical case \(1+\alpha \leqslant \frac{d}{p}+\frac{2}{q}<2+\alpha \) 1 + α d p + 2 q < 2 + α , assuming the initial distribution has an \(L^2\) L 2 -density, we show the existence of weak solutions and associated Markov processes. Moreover, under the additional assumption that \(b=b_1+b_2+\mathord {\textrm{div}}a\) b = b 1 + b 2 + div a , where \(b_1\in {{\mathbb {L}}}^\infty _T{{\textbf{B}}}^{-1}_{\infty ,2}\) b 1 L T B , 2 - 1 , \(b_2\in {{\mathbb {L}}}^2_TL^2\) b 2 L T 2 L 2 , and a is a bounded antisymmetric matrix-valued function, we establish the convergence of mollifying approximation solutions without the need to subtract a subsequence. To illustrate our results, we provide examples of Gaussian random fields and singular interacting particle systems, including the two-dimensional vortex models.