Search for decays of the Higgs boson into scalar particles decaying into four or six b quarks using pp collisions at s=13<mml:…

A search for exotic decays of the Higgs boson <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>H</a:mi></a:math> into new scalar or pseudoscalar particles that subsequently decay into <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>b</c:mi></c:math>-quarks is presented. The search considers <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>Z</e:mi><e:mi>H</e:mi></e:math> production with several decay scenarios for the Higgs boson; first to a pair of identical scalars, <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>H</g:mi><g:mo stretchy="false">→</g:mo><g:mn>2</g:mn><g:mi>a</g:mi><g:mo stretchy="false">→</g:mo><g:mn>4</g:mn><g:mi>b</g:mi></g:math>, second to a pair of scalars with different masses (<k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:msub><k:mi>m</k:mi><k:mrow><k:mi>a</k:mi><k:mn>1</k:mn></k:mrow></k:msub><k:mo><</k:mo><k:msub><k:mi>m</k:mi><k:mrow><k:mi>a</k:mi><k:mn>2</k:mn></k:mrow></k:msub></k:math>), either directly, <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>H</m:mi><m:mo stretchy="false">→</m:mo><m:msub><m:mi>a</m:mi><m:mn>1</m:mn></m:msub><m:msub><m:mi>a</m:mi><m:mn>2</m:mn></m:msub><m:mo stretchy="false">→</m:mo><m:mn>4</m:mn><m:mi>b</m:mi></m:math>, or via a longer decay chain, <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi>H</q:mi><q:mo stretchy="false">→</q:mo><q:msub><q:mi>a</q:mi><q:mn>1</q:mn></q:msub><q:msub><q:mi>a</q:mi><q:mn>2</q:mn></q:msub><q:mo stretchy="false">→</q:mo><q:mn>3</q:mn><q:msub><q:mi>a</q:mi><q:mn>1</q:mn></q:msub><q:mo stretchy="false">→</q:mo><q:mn>6</q:mn><q:mi>b</q:mi></q:math>. The analysis uses proton-proton collision data at <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:msqrt><v:mi>s</v:mi></v:msqrt><v:mo>=</v:mo><v:mn>13</v:mn><v:mtext> </v:mtext><v:mtext> </v:mtext><v:mi>TeV</v:mi></v:math> collected with the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"><x:mn>140</x:mn><x:mtext> </x:mtext><x:mtext> </x:mtext><x:msup><x:mi>fb</x:mi><x:mrow><x:mo>−</x:mo><x:mn>1</x:mn></x:mrow></x:msup></x:math>. No significant excess above the Standard Model prediction is observed. The search sets upper limits at 95% confidence level on the ratio of the Higgs boson production cross section to the SM prediction times the branching ratio of Higgs bosons decaying into <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:mn>4</z:mn><z:mi>b</z:mi></z:math> or <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"><bb:mn>6</bb:mn><bb:mi>b</bb:mi></bb:math>, between 4% and 25% for <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:mrow><db:mi>σ</db:mi><db:mo stretchy="false">(</db:mo><db:mi>Z</db:mi><db:mi>H</db:mi><db:mo stretchy="false">)</db:mo><db:mo>/</db:mo><db:msub><db:mrow><db:mi>σ</db:mi></db:mrow><db:mrow><db:mi>SM</db:mi></db:mrow></db:msub><db:mo stretchy="false">(</db:mo><db:mi>Z</db:mi><db:mi>H</db:mi><db:mo stretchy="false">)</db:mo><db:mo>×</db:mo><db:mi mathvariant="script">B</db:mi><db:mo stretchy="false">(</db:mo><db:mi>H</db:mi><db:mo stretchy="false">→</db:mo><db:mn>2</db:mn><db:mi>a</db:mi><db:mo stretchy="false">→</db:mo><db:mn>4</db:mn><db:mi>b</db:mi><db:mo stretchy="false">)</db:mo></db:mrow></db:math>, between 24% and 38% for <ob:math xmlns:ob="http://www.w3.org/1998/Math/MathML" display="inline"><ob:mrow><ob:mi>σ</ob:mi><ob:mo stretchy="false">(</ob:mo><ob:mi>Z</ob:mi><ob:mi>H</ob:mi><ob:mo stretchy="false">)</ob:mo><ob:mo>/</ob:mo><ob:msub><ob:mrow><ob:mi>σ</ob:mi></ob:mrow><ob:mrow><ob:mi>SM</ob:mi></ob:mrow></ob:msub><ob:mo stretchy="false">(</ob:mo><ob:mi>Z</ob:mi><ob:mi>H</ob:mi><ob:mo stretchy="false">)</ob:mo><ob:mo>×</ob:mo><ob:mspace linebreak="goodbreak"/><ob:mi mathvariant="script">B</ob:mi><ob:mo stretchy="false">(</ob:mo><ob:mi>H</ob:mi><ob:mo stretchy="false">→</ob:mo><ob:msub><ob:mrow><ob:mi>a</ob:mi></ob:mrow><ob:mrow><ob:mn>1</ob:mn></ob:mrow></ob:msub><ob:msub><ob:mrow><ob:mi>a</ob:mi></ob:mrow><ob:mrow><ob:mn>2</ob:mn></ob:mrow></ob:msub><ob:mo stretchy="false">→</ob:mo><ob:mn>4</ob:mn><ob:mi>b</ob:mi><ob:mo stretchy="false">)</ob:mo></ob:mrow></ob:math>, and between 10% and 20% for <ac:math xmlns:ac="http://www.w3.org/1998/Math/MathML" display="inline"><ac:mrow><ac:mi>σ</ac:mi><ac:mo stretchy="false">(</ac:mo><ac:mi>Z</ac:mi><ac:mi>H</ac:mi><ac:mo stretchy="false">)</ac:mo><ac:mo>/</ac:mo><ac:msub><ac:mrow><ac:mi>σ</ac:mi></ac:mrow><ac:mrow><ac:mi>SM</ac:mi></ac:mrow></ac:msub><ac:mo stretchy="false">(</ac:mo><ac:mi>Z</ac:mi><ac:mi>H</ac:mi><ac:mo stretchy="false">)</ac:mo><ac:mo>×</ac:mo><ac:mi mathvariant="script">B</ac:mi><ac:mo stretchy="false">(</ac:mo><ac:mi>H</ac:mi><ac:mo stretchy="false">→</ac:mo><ac:msub><ac:mrow><ac:mi>a</ac:mi></ac:mrow><ac:mrow><ac:mn>1</ac:mn></ac:mrow></ac:msub><ac:msub><ac:mrow><ac:mi>a</ac:mi></ac:mrow><ac:mrow><ac:mn>2</ac:mn></ac:mrow></ac:msub><ac:mo stretchy="false">→</ac:mo><ac:mn>3</ac:mn><ac:msub><ac:mrow><ac:mi>a</ac:mi></ac:mrow><ac:mrow><ac:mn>1</ac:mn></ac:mrow></ac:msub><ac:mo stretchy="false">→</ac:mo><ac:mn>6</ac:mn><ac:mi>b</ac:mi><ac:mo stretchy="false">)</ac:mo></ac:mrow></ac:math>, depending on the masses of the scalar particles.