Search for the lepton flavor violating decay Z→eμ in pp collisions at √s=8 TeV​ with the ATLAS detector

Article, Unknown, Other literature type, Preprint English OPEN
Aad, G. ; Abbott, B. ; Abdallah, J. ; Abdel Khalek, S. ; Abdinov, O. ; Aben, R. ; Abi, B. ; Abolins, M. ; AbouZeid, O. S. ; Abramowicz, H. ; Abreu, H. ; Abreu, R. ; Abulaiti, Y. ; Acharya, B. S. ; Adamczyk, L. ; Adams, D. L. ; Adelman, J. ; Adomeit, S. ; Adye, T. ; Agatonovic-Jovin, T. ; Aguilar-Saavedra, J. A. ; Agustoni, M. ; Ahlen, S. P. ; Ahmadov, F. ; Aielli, G. ; Akerstedt, H. ; Åkesson, T. P. A. ; Akimoto, G. ; Akimov, A. V. ; Alberghi, G. L. ... view all 2,902 authors (2014)
  • Publisher: American Physical Society
  • Journal: (issn: 1550-7998, vol: 90, pp: 72,010)
  • Related identifiers: doi: 10.1103/PhysRevD.90.072010, doi: 10.1103/PhysRevD.90.072010.
  • Subject: scattering [p p] | Subatomic Physics | flavor: violation [lepton] | lepton flavor violating; pp collisions; ATLAS detector | leptonic decay [Z0] | Particle Physics - Experiment | ATLAS | Z0 --> muon electron | mass spectrum [electron muon] | 530 | QC | Physical Sciences | info:eu-repo/classification/ddc/ddc:530 | High Energy Physics - Experiment | Settore FIS/04 - Fisica Nucleare e Subnucleare | mass enhancement | CERN LHC Coll | Particle physics; LHC; Standard Model; Beyond Standard Model | 8000 GeV-cms | experimental results | Subatomär fysik | :Matematikk og naturvitenskap: 400::Fysikk: 430::Kjerne- og elementærpartikkelfysikk: 431 [VDP] | Science & Technology | Fysik | :Mathematics and natural scienses: 400::Physics: 430::Nuclear and elementary particle physics: 431 [VDP] | Settore FIS/01 - Fisica Sperimentale | branching ratio: upper limit [Z0] | 530 Physics
    • ddc: ddc:530

The ATLAS detector at the Large Hadron Collider is used to search for the lepton flavor violating process $Z \rightarrow e\mu$ in $pp$ collisions using $20.3~\textrm{fb}^{-1}$ of data collected at $\sqrt{s}= 8~\textrm{TeV}$. An enhancement in the $e\mu$ invariant mass spectrum is searched for at the $Z$ boson mass. The number of $Z$ bosons produced in the data sample is estimated using events of similar topology, $Z \rightarrow ee$ and $\mu\mu$, significantly reducing the systematic uncertainty in the measurement. There is no evidence of an enhancement at the $Z$ boson mass, resulting in an upper limit on the branching fraction, ${\cal B}(Z~\rightarrow~e\mu)~<~7.5 \times 10^{-7}$ at the 95% confidence level. <p>The ATLAS detector at the Large Hadron Collider is used to search for the lepton flavor violating process <inline-formula><mml:math display="inline"><mml:mi>Z</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>e</mml:mi><mml:mi>μ</mml:mi></mml:math></inline-formula> in <inline-formula><mml:math display="inline"><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:math></inline-formula> collisions using <inline-formula><mml:math display="inline"><mml:mrow><mml:mn>20.3</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>fb</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math></inline-formula> of data collected at <inline-formula><mml:math display="inline"><mml:mrow><mml:msqrt><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:msqrt><mml:mo>=</mml:mo><mml:mn>8</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:mrow></mml:math></inline-formula>. An enhancement in the <inline-formula><mml:math display="inline"><mml:mi>e</mml:mi><mml:mi>μ</mml:mi></mml:math></inline-formula> invariant mass spectrum is searched for at the <inline-formula><mml:math display="inline"><mml:mi>Z</mml:mi></mml:math></inline-formula>-boson mass. The number of <inline-formula><mml:math display="inline"><mml:mi>Z</mml:mi></mml:math></inline-formula> bosons produced in the data sample is estimated using events of similar topology, <inline-formula><mml:math display="inline"><mml:mi>Z</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>e</mml:mi><mml:mi>e</mml:mi></mml:math></inline-formula> and <inline-formula><mml:math display="inline"><mml:mi>μ</mml:mi><mml:mi>μ</mml:mi></mml:math></inline-formula>, significantly reducing the systematic uncertainty in the measurement. There is no evidence of an enhancement at the <inline-formula><mml:math display="inline"><mml:mi>Z</mml:mi></mml:math></inline-formula>-boson mass, resulting in an upper limit on the branching fraction, <inline-formula><mml:math display="inline"><mml:mrow><mml:mi mathvariant="script">B</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>Z</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>e</mml:mi><mml:mi>μ</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mo>&lt;</mml:mo><mml:mn>7.5</mml:mn><mml:mo>×</mml:mo><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math></inline-formula> at the 95% confidence level.</p> The ATLAS detector at the Large Hadron Collider is used to search for the lepton flavor violating process $Z \rightarrow e \mu$ in pp collisions using 20.3 $fb^{-1}$ of data collected at $\sqrt{s}$ = 8 TeV. An enhancement in the $e \mu$ invariant mass spectrum is searched for at the Z boson mass. The number of Z bosons produced in the data sample is estimated using events of similar topology, $Z \rightarrow ee$ and $\mu \mu$, significantly reducing the systematic uncertainty in the measurement. There is no evidence of an enhancement at the Z boson mass, resulting in an upper limit on the branching fraction, $B(Z \rightarrow e \mu)$ < 7.5 x 10$^{-7}$ at the 95% confidence level.
Share - Bookmark