<p>Within the framework of NRQCD, the photoproduction of doubly heavy baryons Ξ<sub><i>cc</i></sub>, Ξ<sub><i>bc</i></sub>, Ξ<sub><i>bb</i></sub> and their <i>P</i>-wave excited states has been systematically investigated. The production mechanism is that a color anti-triplet or sextuplet diquark ⟨<i>QQ</i><sup>′</sup>⟩ is first produced, and then evolved into a corresponding doubly heavy baryon <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="35" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msub> <mi mathvariant="normal">Ξ</mi> <msup> <mi mathvariant="italic">QQ</mi> <mo>′</mo> </msup> </msub> </math></EquationSource> <EquationSource Format="TEX">\( {\Xi}_{QQ^{\prime }} \)</EquationSource> </InlineEquation> via the subprocess <i>γ</i> + <i>γ</i> → ⟨<i>QQ</i><sup>′</sup>⟩[<i>n</i>] + <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq3.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msup> <mover accent="true"> <mi>Q</mi> <mo stretchy="true">¯</mo> </mover> <mo>′</mo> </msup> </math></EquationSource> <EquationSource Format="TEX">\( {\overline{Q}}^{\prime } \)</EquationSource> </InlineEquation> + <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq4.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <mover accent="true"> <mi>Q</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( \overline{Q} \)</EquationSource> </InlineEquation> → <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="35" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msub> <mi mathvariant="normal">Ξ</mi> <msup> <mi mathvariant="italic">QQ</mi> <mo>′</mo> </msup> </msub> </math></EquationSource> <EquationSource Format="TEX">\( {\Xi}_{QQ^{\prime }} \)</EquationSource> </InlineEquation> + <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq3.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msup> <mover accent="true"> <mi>Q</mi> <mo stretchy="true">¯</mo> </mover> <mo>′</mo> </msup> </math></EquationSource> <EquationSource Format="TEX">\( {\overline{Q}}^{\prime } \)</EquationSource> </InlineEquation> + <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq4.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <mover accent="true"> <mi>Q</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( \overline{Q} \)</EquationSource> </InlineEquation>. Here, <i>Q</i><sup>(′)</sup> denotes the heavy quark <i>b</i> or <i>c</i>, [<i>n</i>] is the color and spin quantum number of intermediate diquark, which can be <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq8.gif" Format="GIF" Height="26" Rendition="HTML" Resolution="72" Type="Linedraw" Width="58" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msub> <mfenced close="]" open="["> <mmultiscripts> <msub> <mi>S</mi> <mn>1</mn> </msub> <mprescripts /> <none /> <mn>3</mn> </mmultiscripts> </mfenced> <mrow> <mover accent="true"> <mn mathvariant="bold">3</mn> <mo stretchy="true">¯</mo> </mover> <mo>/</mo> <mn mathvariant="bold">6</mn> </mrow> </msub> </math></EquationSource> <EquationSource Format="TEX">\( {\left[^3{S}_1\right]}_{\overline{\textbf{3}}/\textbf{6}} \)</EquationSource> </InlineEquation> and <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq9.gif" Format="GIF" Height="26" Rendition="HTML" Resolution="72" Type="Linedraw" Width="58" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msub> <mfenced close="]" open="["> <mmultiscripts> <msub> <mi>S</mi> <mn>0</mn> </msub> <mprescripts /> <none /> <mn>1</mn> </mmultiscripts> </mfenced> <mrow> <mover accent="true"> <mn mathvariant="bold">3</mn> <mo stretchy="true">¯</mo> </mover> <mo>/</mo> <mn mathvariant="bold">6</mn> </mrow> </msub> </math></EquationSource> <EquationSource Format="TEX">\( {\left[^1{S}_0\right]}_{\overline{\textbf{3}}/\textbf{6}} \)</EquationSource> </InlineEquation> for <i>S</i>-wave states, or <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq10.gif" Format="GIF" Height="26" Rendition="HTML" Resolution="72" Type="Linedraw" Width="59" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msub> <mfenced close="]" open="["> <mmultiscripts> <msub> <mi>P</mi> <mn>1</mn> </msub> <mprescripts /> <none /> <mn>1</mn> </mmultiscripts> </mfenced> <mrow> <mover accent="true"> <mn mathvariant="bold">3</mn> <mo stretchy="true">¯</mo> </mover> <mo>/</mo> <mn mathvariant="bold">6</mn> </mrow> </msub> </math></EquationSource> <EquationSource Format="TEX">\( {\left[^1{P}_1\right]}_{\overline{\textbf{3}}/\textbf{6}} \)</EquationSource> </InlineEquation> and <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq11.gif" Format="GIF" Height="26" Rendition="HTML" Resolution="72" Type="Linedraw" Width="61" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msub> <mfenced close="]" open="["> <mmultiscripts> <msub> <mi>P</mi> <mi>J</mi> </msub> <mprescripts /> <none /> <mn>3</mn> </mmultiscripts> </mfenced> <mrow> <mover accent="true"> <mn mathvariant="bold">3</mn> <mo stretchy="true">¯</mo> </mover> <mo>/</mo> <mn mathvariant="bold">6</mn> </mrow> </msub> </math></EquationSource> <EquationSource Format="TEX">\( {\left[^3{P}_J\right]}_{\overline{\textbf{3}}/\textbf{6}} \)</EquationSource> </InlineEquation> with <i>J</i> = 0, 1, 2 for <i>P</i>-wave states. Predictions for the cross sections, differential distributions, and theoretical uncertainty have been analyzed. The results indicate that, at <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq12.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="30" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <msqrt> <mi>s</mi> </msqrt> </math></EquationSource> <EquationSource Format="TEX">\( \sqrt{s} \)</EquationSource> </InlineEquation> = 91 GeV, the contribution of photoproduction for <i>P</i>-wave Ξ<sub><i>cc</i></sub>, Ξ<sub><i>bc</i></sub>, and Ξ<sub><i>bb</i></sub> is approximately 2<i>.</i>19%, 4<i>.</i>23%, 1<i>.</i>26% of the contribution for <i>S</i>-wave, respectively. As the collision energy increases, the contribution of <i>P</i>-wave also increases. Assuming that the highly excited state can decay into ground state with 100% efficiency, the total produced events at CEPC and FCC-ee can be as high as <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq13.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="57" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <mi mathvariant="script">O</mi> <mfenced close=")" open="("> <msup> <mn>10</mn> <mn>8</mn> </msup> </mfenced> </math></EquationSource> <EquationSource Format="TEX">\( \mathcal{O}\left({10}^8\right) \)</EquationSource> </InlineEquation>, <InlineEquation ID="IEq14"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq14.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="57" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <mi mathvariant="script">O</mi> <mfenced close=")" open="("> <msup> <mn>10</mn> <mn>7</mn> </msup> </mfenced> </math></EquationSource> <EquationSource Format="TEX">\( \mathcal{O}\left({10}^7\right) \)</EquationSource> </InlineEquation><i>,</i> and <InlineEquation ID="IEq15"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13130_2025_26272_Article_IEq15.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="57" /> </InlineMediaObject> <EquationSource Format="MATHML"><math display="inline"> <mi mathvariant="script">O</mi> <mfenced close=")" open="("> <msup> <mn>10</mn> <mn>5</mn> </msup> </mfenced> </math></EquationSource> <EquationSource Format="TEX">\( \mathcal{O}\left({10}^5\right) \)</EquationSource> </InlineEquation> corresponding to Ξ<sub><i>cc</i></sub>, Ξ<sub><i>bc</i></sub>, and Ξ<sub><i>bb</i></sub>, respectively, which is very promising to be detected in future experiments.</p>

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Further study on excited \( {\Xi}_{QQ^{\prime }} \) via photoproduction at CEPC and FCC-ee

  • Hong-Hao Ma,
  • Juan-Juan Niu,
  • Lei Guo

摘要

Within the framework of NRQCD, the photoproduction of doubly heavy baryons Ξcc, Ξbc, Ξbb and their P-wave excited states has been systematically investigated. The production mechanism is that a color anti-triplet or sextuplet diquark ⟨QQ⟩ is first produced, and then evolved into a corresponding doubly heavy baryon Ξ QQ \( {\Xi}_{QQ^{\prime }} \) via the subprocess γ + γ → ⟨QQ⟩[n] + Q ¯ \( {\overline{Q}}^{\prime } \) + Q ¯ \( \overline{Q} \) Ξ QQ \( {\Xi}_{QQ^{\prime }} \) + Q ¯ \( {\overline{Q}}^{\prime } \) + Q ¯ \( \overline{Q} \) . Here, Q(′) denotes the heavy quark b or c, [n] is the color and spin quantum number of intermediate diquark, which can be S 1 3 3 ¯ / 6 \( {\left[^3{S}_1\right]}_{\overline{\textbf{3}}/\textbf{6}} \) and S 0 1 3 ¯ / 6 \( {\left[^1{S}_0\right]}_{\overline{\textbf{3}}/\textbf{6}} \) for S-wave states, or P 1 1 3 ¯ / 6 \( {\left[^1{P}_1\right]}_{\overline{\textbf{3}}/\textbf{6}} \) and P J 3 3 ¯ / 6 \( {\left[^3{P}_J\right]}_{\overline{\textbf{3}}/\textbf{6}} \) with J = 0, 1, 2 for P-wave states. Predictions for the cross sections, differential distributions, and theoretical uncertainty have been analyzed. The results indicate that, at s \( \sqrt{s} \) = 91 GeV, the contribution of photoproduction for P-wave Ξcc, Ξbc, and Ξbb is approximately 2.19%, 4.23%, 1.26% of the contribution for S-wave, respectively. As the collision energy increases, the contribution of P-wave also increases. Assuming that the highly excited state can decay into ground state with 100% efficiency, the total produced events at CEPC and FCC-ee can be as high as O 10 8 \( \mathcal{O}\left({10}^8\right) \) , O 10 7 \( \mathcal{O}\left({10}^7\right) \) , and O 10 5 \( \mathcal{O}\left({10}^5\right) \) corresponding to Ξcc, Ξbc, and Ξbb, respectively, which is very promising to be detected in future experiments.