New constraints on CPT symmetry violation in charm mesons

Small <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>C</a:mi><a:mi>P</a:mi><a:mi>T</a:mi></a:mrow></a:math>-violating effects are admissible in several theories beyond the Standard Model of interactions. We analyze experimental data obtained with neutral flavored meson mixing and place bounds on the scale of such phenomena. The constraints on the <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>C</c:mi><c:mi>P</c:mi><c:mi>T</c:mi></c:math>-violating parameter <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>z</e:mi></e:math> are derived by reinterpreting the LHCb measurement of the time-dependent asymmetry in the Cabbibo-favored <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msup><g:mi>D</g:mi><g:mn>0</g:mn></g:msup><g:mo stretchy="false">→</g:mo><g:msup><g:mi>K</g:mi><g:mo>−</g:mo></g:msup><g:msup><g:mi>π</g:mi><g:mo>+</g:mo></g:msup></g:math> and <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:mover accent="true"><j:msup><j:mi>D</j:mi><j:mn>0</j:mn></j:msup><j:mo stretchy="true">¯</j:mo></j:mover><j:mo stretchy="false">→</j:mo><j:msup><j:mi>K</j:mi><j:mo>+</j:mo></j:msup><j:msup><j:mi>π</j:mi><j:mo>−</j:mo></j:msup></j:math> decay rates. The bounds provided in this paper are 2 orders of magnitude stricter compared to the results obtained by the FOCUS Collaboration. Among other constraints, we report bounds on the differences in the decay widths and masses of the neutral <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mrow><o:mi>D</o:mi></o:mrow></o:math> meson flavor states at a 95% confidence level. The decay width difference is bounded by <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mo stretchy="false">(</q:mo><q:mo>−</q:mo><q:mn>4.7</q:mn><q:mo><</q:mo><q:mi>δ</q:mi><q:msub><q:mi mathvariant="normal">Γ</q:mi><q:mi>D</q:mi></q:msub><q:mo><</q:mo><q:mn>2.1</q:mn><q:mo stretchy="false">)</q:mo><q:mo>×</q:mo><q:msup><q:mn>10</q:mn><q:mrow><q:mo>−</q:mo><q:mn>16</q:mn></q:mrow></q:msup><q:mtext> </q:mtext><q:mtext> </q:mtext><q:mi>GeV</q:mi></q:math>. The mass difference lies within <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:mo stretchy="false">(</v:mo><v:mo>−</v:mo><v:mn>2.0</v:mn><v:mo><</v:mo><v:mi>δ</v:mi><v:msub><v:mi>m</v:mi><v:mi>D</v:mi></v:msub><v:mo><</v:mo><v:mn>2.0</v:mn><v:mo stretchy="false">)</v:mo><v:mo>×</v:mo><v:msup><v:mn>10</v:mn><v:mrow><v:mo>−</v:mo><v:mn>15</v:mn></v:mrow></v:msup><v:mtext> </v:mtext><v:mtext> </v:mtext><v:mi>GeV</v:mi></v:math> for 95% of <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:mi>arg</z:mi><z:mo stretchy="false">(</z:mo><z:mi>z</z:mi><z:mo stretchy="false">)</z:mo></z:math> values. The paper includes an assessment of the influence of <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:mi>C</db:mi><db:mi>P</db:mi></db:math> violation on the results and a discussion of the future prospects.