Observation of an excited B±c meson state 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 2,884 authors (2014)
  • Publisher: American Physical Society
  • Journal: (issn: 1079-7114, vol: 113, pp: 212,004)
  • Related identifiers: doi: 10.1103/PhysRevLett.113.212004, doi: 10.1103/PhysRevLett.113.212004.
  • Subject: scattering [p p] | Subatomic Physics | ATLAS Detector; Meson State | Particle Physics - Experiment | ATLAS | мезоны | B-C Meson | B-C meson; spectroscopy; equation | ATLAS, детектор | mass difference | QC | 530 | Physical Sciences | Spectroscopy | Physics and Astronomy (all) | High Energy Physics - Experiment | B/c+ | Settore FIS/04 - Fisica Nucleare e Subnucleare | CERN LHC Coll | B/c+ --> J/psi(3100) pi+ | experimental results | Subatomär fysik | vtls000526497 | Equation | mass [excited state] | (J/psi(3100) pi+) [mass spectrum] | hadronic decay [excited state] | Большой адронный коллайдер | hadronic decay [B/c+] | :Matematikk og naturvitenskap: 400::Fysikk: 430::Kjerne- og elementærpartikkelfysikk: 431 [VDP] | Fysik | Science & Technology | :Mathematics and natural scienses: 400::Physics: 430::Nuclear and elementary particle physics: 431 [VDP] | Settore FIS/01 - Fisica Sperimentale | B/c* --> B/c+ pi+ pi- | excited state | 8000 GeV-cms [7000]

A search for excited states of the $B^{\pm}_c$ meson is performed using 4.9 fb$^{-1}$ of 7 TeV and 19.2 fb$^{-1}$ of 8 TeV $pp$ collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadronic transition to the ground state, with the latter detected in the decay $B_c^{\pm} \to J/\psi \pi^{\pm}$. The state appears in the $m(B_c^{\pm}\pi^{+}\pi^{-})-m(B_c^{\pm})-2m(\pi^{\pm})$ mass difference distribution with a significance of 5.2 standard deviations. The mass of the observed state is $6842 \pm 4 \pm 5$~MeV, where the first error is statistical and the second is systematic. The mass and decay of this state are consistent with expectations for the second $S\mbox{-}$wave state of the $B^{\pm}_c$ meson, $B^{\pm}_c(2S)$. <p>A search for excited states of the <inline-formula><mml:math display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula> meson is performed using <inline-formula><mml:math display="inline"><mml:mrow><mml:mn>4.9</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 7 TeV and <inline-formula><mml:math display="inline"><mml:mrow><mml:mn>19.2</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 8 TeV <inline-formula><mml:math display="inline"><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:math></inline-formula> collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadronic transition to the ground state, with the latter detected in the decay <inline-formula><mml:math display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:msubsup><mml:mo stretchy="false">→</mml:mo><mml:mi>J</mml:mi><mml:mo stretchy="false">/</mml:mo><mml:mi>ψ</mml:mi><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math></inline-formula>. The state appears in the <inline-formula><mml:math display="inline"><mml:mrow><mml:mi>m</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:msubsup><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:msubsup><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msup><mml:mo stretchy="false">)</mml:mo><mml:mo>-</mml:mo><mml:mi>m</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:msubsup><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:msubsup><mml:mo stretchy="false">)</mml:mo><mml:mo>-</mml:mo><mml:mn>2</mml:mn><mml:mi>m</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:msup><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math></inline-formula> mass difference distribution with a significance of 5.2 standard deviations. The mass of the observed state is <inline-formula><mml:math display="inline"><mml:mrow><mml:mn>6842</mml:mn><mml:mo>±</mml:mo><mml:mn>4</mml:mn><mml:mo>±</mml:mo><mml:mn>5</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>MeV</mml:mi></mml:mrow></mml:math></inline-formula>, where the first error is statistical and the second is systematic. The mass and decay of this state are consistent with expectations for the second <inline-formula><mml:math display="inline"><mml:mrow><mml:mi>S</mml:mi></mml:mrow></mml:math></inline-formula>-wave state of the <inline-formula><mml:math display="inline"><mml:msubsup><mml:mi>B</mml:mi><mml:mi>c</mml:mi><mml:mo>±</mml:mo></mml:msubsup></mml:math></inline-formula> meson, <inline-formula><mml:math display="inline"><mml:msubsup><mml:mi>B</mml:mi><mml:mi>c</mml:mi><mml:mo>±</mml:mo></mml:msubsup><mml:mo stretchy="false">(</mml:mo><mml:mn>2</mml:mn><mml:mi>S</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:math></inline-formula>.</p> A search for excited states of the $B^{\pm}_c$ meson is performed using 4.9 fb$^{-1}$ of 7 TeV and 19.2 fb$^{-1}$ of 8 TeV $pp$ collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadronic transition to the ground state, with the latter detected in the decay $B_c^{\pm} \to J/\psi \pi^{\pm}$. The state appears in the $m(B_c^{\pm}\pi^{+}\pi^{-})-m(B_c^{\pm})-2m(\pi^{\pm})$ mass difference distribution with a significance of 5.2 standard deviations. The mass of the observed state is $6842 \pm 4 \pm 5$ MeV, where the first error is statistical and the second is systematic. The mass and decay of this state are consistent with expectations for the second $S\mbox{-}$wave state of the $B^{\pm}_c$ meson, $B^{\pm}_c(2S)$.