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T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., Fernandez, P., Izmaylov, A., & Novella, P. (2019). Search for neutral-current induced single photon production at the ND280 near detector in T2K. J. Phys. G, 46(8), 08LT01–16pp.
Abstract: Neutrino neutral-current (NC) induced single photon production is a sub-leading order process for accelerator-based neutrino beam experiments including T2K. It is, however, an important process to understand because it is a background for electron (anti)neutrino appearance oscillation experiments. Here, we performed the first search of this process below 1 GeV using the fine-grained detector at the T2K ND280 off-axis near detector. By reconstructing single photon kinematics from electron-positron pairs, we achieved 95% pure gamma ray sample from 5.738 x 10(20) protons-on-targets neutrino mode data. We do not find positive evidence of NC induced single photon production in this sample. We set the model-dependent upper limit on the cross-section for this process, at 0.114 x 10(-38) cm(2) (90% C.L.) per nucleon, using the J-PARC off-axis neutrino beam with an average energy of < E-v > similar to 0.6 GeV. This is the first limit on this process below 1 GeV which is important for current and future oscillation experiments looking for electron neutrino appearance oscillation signals.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Search for CP violation using triple product asymmetries in Lambda(0)(b) -> pK(-) pi(+) pi(-), Lambda(0)(b) -> pK(-) K+ K- and Xi(0)(b) -> pK(-) K- pi(+) decays. J. High Energy Phys., 08(8), 039–27pp.
Abstract: A search for CP and P violation using triple- product asymmetries is performed with Lambda(0)(b) -> pK(-) pi(+) pi(-), Lambda(0)(b) -> pK(-) K+ K- and Xi(0)(b) -> pK(-) K- pi(+) decays. The data sample corresponds to integrated luminosities of 1.0 fb(-1) and 2.0 fb(-1), recorded with the LHCb detector at centre- of- mass energies of 7TeV and 8TeV, respectively. The CP- and P-violating asymmetries are measured both integrating over all phase space and in speci fi c phase- space regions. No signi fi cant deviation from CP or P symmetry is found. The fi rst observation of Lambda(0)(b) -> pK(-) chi(c0) (1P)(->pi(+) pi(-), K+ K-) decay is also reported.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Search for CP violation using T-odd correlations in D-0 -> K+K-pi(+)pi(-) decays. J. High Energy Phys., 10(10), 005–21pp.
Abstract: A search for CP violation using T-odd correlations is performed using the four-body D-0 -> K+K-pi(+)pi(-) decay, selected from semileptonic B decays. The data sample corresponds to integrated luminosities of 1.0 fb(-1) and 2.0 fb(-1) recorded at the centre-of-mass energies of 7 TeV and 8 TeV, respectively. The CP-violating asymmetry alpha(T-odd)(CP) is measured to be (0.18 +/- 0.29 (stat) +/- 0.04 (syst))%. Searches for CP violation in different regions of phase space of the four-body decay, and as a function of the D-0 decay time, are also presented. No significant deviation from the CP conservation hypothesis is found.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). Search for CP violation through an amplitude analysis of D-0 K+K-+- decays. J. High Energy Phys., 02(2), 126–34pp.
Abstract: A search for CP violation in the Cabibbo-suppressed D-0 K+K-+- decay mode is performed using an amplitude analysis. The measurement uses a sample of pp collisions recorded by the LHCb experiment during 2011 and 2012, corresponding to an integrated luminosity of 3.0 fb(-1). The D-0 mesons are reconstructed from semileptonic b-hadron decays into D0-X final states. The selected sample contains more than 160 000 signal decays, allowing the most precise amplitude modelling of this D-0 decay to date. The obtained amplitude model is used to perform the search for CP violation. The result is compatible with CP symmetry, with a sensitivity ranging from 1% to 15% depending on the amplitude considered.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Search for CP violation in the phase space of D0 → π-π+π0 decays with the energy test. J. High Energy Phys., 09(9), 129–24pp.
Abstract: A search for CP violation in D-0 -> pi(-)pi(+)pi(0) decays is reported, using pp collision data collected by the LHCb experiment from 2015 to 2018 corresponding to an integrated luminosity of 6 fb(-1). An unbinned model-independent approach provides sensitivity to local CP violation within the two-dimensional phase space of the decay. The method is validated using the Cabibbo-favoured channel D-0 -> K-pi(+)pi(0) and background regions of the signal mode. The results are consistent with CP symmetry in this decay.
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