<p>Let <i>L</i> be a holomorphic line bundle over a compact locally conformally Kähler manifold <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="63" /> </InlineMediaObject> <EquationSource Format="TEX">\((X,\omega ,\theta )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>X</mi> <mo>,</mo> <mi>ω</mi> <mo>,</mo> <mi>θ</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> with negative sectional curvature <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="107" /> </InlineMediaObject> <EquationSource Format="TEX">\(sec\le -K&lt;0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>s</mi> <mi>e</mi> <mi>c</mi> <mo>≤</mo> <mo>-</mo> <mi>K</mi> <mo>&lt;</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation>. Let <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq3.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="176" /> </InlineMediaObject> <EquationSource Format="TEX">\(\pi :(\tilde{X},\tilde{\omega },\tilde{\theta })\rightarrow (X,\omega ,\theta )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>π</mi> <mo>:</mo> <mrow> <mo stretchy="false">(</mo> <mover accent="true"> <mi>X</mi> <mo stretchy="false">~</mo> </mover> <mo>,</mo> <mover accent="true"> <mi>ω</mi> <mo stretchy="false">~</mo> </mover> <mo>,</mo> <mover accent="true"> <mi>θ</mi> <mo stretchy="false">~</mo> </mover> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">→</mo> <mrow> <mo stretchy="false">(</mo> <mi>X</mi> <mo>,</mo> <mi>ω</mi> <mo>,</mo> <mi>θ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> be the universal covering map for <i>X</i>. In this article, we first observe that the fundamental form <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq4.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">\(\tilde{\omega }\)</EquationSource> <EquationSource Format="MATHML"><math> <mover accent="true"> <mi>ω</mi> <mo stretchy="false">~</mo> </mover> </math></EquationSource> </InlineEquation> of <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq5.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\tilde{X}\)</EquationSource> <EquationSource Format="MATHML"><math> <mover accent="true"> <mi>X</mi> <mo stretchy="false">~</mo> </mover> </math></EquationSource> </InlineEquation> is <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq6.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="27" /> </InlineMediaObject> <EquationSource Format="TEX">\(d_{-\tilde{\theta }}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>d</mi> <mrow> <mo>-</mo> <mover accent="true"> <mi>θ</mi> <mo stretchy="false">~</mo> </mover> </mrow> </msub> </math></EquationSource> </InlineEquation> exact. Specifically, there exists a 1-form <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq7.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">\(\eta \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>η</mi> </math></EquationSource> </InlineEquation> such that <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq8.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="111" /> </InlineMediaObject> <EquationSource Format="TEX">\(\tilde{\omega }=d\eta -\tilde{\theta }\wedge \eta \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mover accent="true"> <mi>ω</mi> <mo stretchy="false">~</mo> </mover> <mo>=</mo> <mi>d</mi> <mi>η</mi> <mo>-</mo> <mover accent="true"> <mi>θ</mi> <mo stretchy="false">~</mo> </mover> <mo>∧</mo> <mi>η</mi> </mrow> </math></EquationSource> </InlineEquation>. Moreover, under the assumption <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq9.gif" Format="GIF" Height="24" Rendition="HTML" Resolution="72" Type="Linedraw" Width="107" /> </InlineMediaObject> <EquationSource Format="TEX">\(\Vert \theta \Vert ^{2}_{L^{\infty }(X)}&lt;K\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mrow> <mo stretchy="false">‖</mo> <mi>θ</mi> <mo stretchy="false">‖</mo> </mrow> <mrow> <msup> <mi>L</mi> <mi>∞</mi> </msup> <mrow> <mo stretchy="false">(</mo> <mi>X</mi> <mo stretchy="false">)</mo> </mrow> </mrow> <mn>2</mn> </msubsup> <mo>&lt;</mo> <mi>K</mi> </mrow> </math></EquationSource> </InlineEquation>, we can prove that <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq7.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">\(\eta \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>η</mi> </math></EquationSource> </InlineEquation> is bounded. Finally, building upon the boundedness of <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq7.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">\(\eta \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>η</mi> </math></EquationSource> </InlineEquation>, we derive a lower bound for the Euler characteristic <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq12.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="41" /> </InlineMediaObject> <EquationSource Format="TEX">\(\chi (X)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>χ</mi> <mo stretchy="false">(</mo> <mi>X</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> of <i>X</i> under the non-vanishing condition <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq13.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="92" /> </InlineMediaObject> <EquationSource Format="TEX">\(\int _{X}c^{n}_{1}(L)\ne 0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mo>∫</mo> <mi>X</mi> </msub> <msubsup> <mi>c</mi> <mn>1</mn> <mi>n</mi> </msubsup> <mrow> <mo stretchy="false">(</mo> <mi>L</mi> <mo stretchy="false">)</mo> </mrow> <mo>≠</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation>. Specifically, we show that <InlineEquation ID="IEq14"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq14.gif" Format="GIF" Height="25" Rendition="HTML" Resolution="72" Type="Linedraw" Width="231" /> </InlineMediaObject> <EquationSource Format="TEX">\((-1)^{n}\chi (X)\ge (n+1)+\lfloor \frac{C(n)K}{nC} \rfloor \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mrow> <mo stretchy="false">(</mo> <mo>-</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> <mi>n</mi> </msup> <mi>χ</mi> <mrow> <mo stretchy="false">(</mo> <mi>X</mi> <mo stretchy="false">)</mo> </mrow> <mo>≥</mo> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo>+</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> <mo>+</mo> <mrow> <mo>⌊</mo> <mfrac> <mrow> <mi>C</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> <mi>K</mi> </mrow> <mrow> <mi mathvariant="italic">nC</mi> </mrow> </mfrac> <mo>⌋</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq15"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12220_2025_2175_Article_IEq15.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="117" /> </InlineMediaObject> <EquationSource Format="TEX">\(C:=|[\Theta (L),\Lambda ]|\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>C</mi> <mo>:</mo> <mo>=</mo> <mo stretchy="false">|</mo> <mo stretchy="false">[</mo> <mi mathvariant="normal">Θ</mi> <mo stretchy="false">(</mo> <mi>L</mi> <mo stretchy="false">)</mo> <mo>,</mo> <mi mathvariant="normal">Λ</mi> <mo stretchy="false">]</mo> <mo stretchy="false">|</mo> </mrow> </math></EquationSource> </InlineEquation> is a constant determined by the curvature of <i>L</i>.</p>

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Negatively Curved Locally Conformally Kähler Manifolds

  • Teng Huang,
  • Weiwei Wang

摘要

Let L be a holomorphic line bundle over a compact locally conformally Kähler manifold \((X,\omega ,\theta )\) ( X , ω , θ ) with negative sectional curvature \(sec\le -K<0\) s e c - K < 0 . Let \(\pi :(\tilde{X},\tilde{\omega },\tilde{\theta })\rightarrow (X,\omega ,\theta )\) π : ( X ~ , ω ~ , θ ~ ) ( X , ω , θ ) be the universal covering map for X. In this article, we first observe that the fundamental form \(\tilde{\omega }\) ω ~ of \(\tilde{X}\) X ~ is \(d_{-\tilde{\theta }}\) d - θ ~ exact. Specifically, there exists a 1-form \(\eta \) η such that \(\tilde{\omega }=d\eta -\tilde{\theta }\wedge \eta \) ω ~ = d η - θ ~ η . Moreover, under the assumption \(\Vert \theta \Vert ^{2}_{L^{\infty }(X)}<K\) θ L ( X ) 2 < K , we can prove that \(\eta \) η is bounded. Finally, building upon the boundedness of \(\eta \) η , we derive a lower bound for the Euler characteristic \(\chi (X)\) χ ( X ) of X under the non-vanishing condition \(\int _{X}c^{n}_{1}(L)\ne 0\) X c 1 n ( L ) 0 . Specifically, we show that \((-1)^{n}\chi (X)\ge (n+1)+\lfloor \frac{C(n)K}{nC} \rfloor \) ( - 1 ) n χ ( X ) ( n + 1 ) + C ( n ) K nC , where \(C:=|[\Theta (L),\Lambda ]|\) C : = | [ Θ ( L ) , Λ ] | is a constant determined by the curvature of L.