The first study of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>J</a:mi><a:mo>/</a:mo><a:mi>ψ</a:mi><a:mi>ϕ</a:mi></a:math> production in diffractive processes in proton-proton collisions is presented. The study is based on an LHCb dataset recorded at center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mn>5</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:msup><c:mi>fb</c:mi><c:mrow><c:mo>−</c:mo><c:mn>1</c:mn></c:mrow></c:msup></c:math>. The data disfavor a nonresonant <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>J</e:mi><e:mo>/</e:mo><e:mi>ψ</e:mi><e:mi>ϕ</e:mi></e:math> production but are consistent with a resonant model including several resonant states observed previously only in <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:msup><g:mrow><g:mi>B</g:mi></g:mrow><g:mrow><g:mo>+</g:mo></g:mrow></g:msup><g:mo stretchy="false">→</g:mo><g:mi>J</g:mi><g:mo>/</g:mo><g:mi>ψ</g:mi><g:mi>ϕ</g:mi><g:msup><g:mrow><g:mi>K</g:mi></g:mrow><g:mrow><g:mo>+</g:mo></g:mrow></g:msup></g:mrow></g:math> decays. The <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:msub><j:mi>χ</j:mi><j:mrow><j:mi>c</j:mi><j:mn>0</j:mn></j:mrow></j:msub><j:mo stretchy="false">(</j:mo><j:mn>4500</j:mn><j:mo stretchy="false">)</j:mo></j:math> state is observed with a significance over <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"><n:mn>6</n:mn><n:mi>σ</n:mi></n:math> and the <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline"><p:msub><p:mi>χ</p:mi><p:mrow><p:mi>c</p:mi><p:mn>1</p:mn></p:mrow></p:msub><p:mo stretchy="false">(</p:mo><p:mn>4274</p:mn><p:mo stretchy="false">)</p:mo></p:math> is confirmed with a significance of more than <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mn>4</t:mn><t:mi>σ</t:mi></t:math>. © 2025 CERN, for the LHCb Collaboration 2025 CERN