ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2023). Pursuit of paired dijet resonances in the Run 2 dataset with ATLAS. Phys. Rev. D, 108(11), 112005–30pp.
Abstract: New particles with large masses that decay into hadronically interacting particles are predicted by many models of physics beyond the Standard Model. A search for a massive resonance that decays into pairs of dijet resonances is performed using 140 fb(-1) of proton-proton collisions at ffiffiffisp root s = 13 TeV recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Resonances are searched for in the invariant mass of the tetrajet system, and in the average invariant mass of the pair of dijet systems. A data-driven background estimate is obtained by fitting the tetrajet and dijet invariant mass distributions with a four-parameter dijet function and a search for local excesses from resonant production of dijet pairs is performed. No significant excess of events beyond the Standard Model expectation is observed, and upper limits are set on the production cross sections of new physics scenarios.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Search for dark matter in association with a Higgs boson decaying to two photons at root s=13 TeV with the ATLAS detector. Phys. Rev. D, 96(11), 112004–31pp.
Abstract: A search for dark matter in association with a Higgs boson decaying to two photons is presented. This study is based on data collected with the ATLAS detector, corresponding to an integrated luminosity of 36.1 fb(-1) of proton-proton collisions at the LHC at a center-of-mass energy of 13 TeV in 2015 and 2016. No significant excess over the expected background is observed. Upper limits at 95% confidence level are set on the visible cross section for beyond the Standard Model physics processes, and the production cross section times branching fraction of the Standard Model Higgs boson decaying into two photons in association with missing transverse momentum in three different benchmark models. Limits at 95% confidence level are also set on the observed signal in two-dimensional mass planes. Additionally, the results are interpreted in terms of 90% confidence-level limits on the dark-matternucleon scattering cross section, as a function of the dark-matter particle mass, for a spin-independent scenario.
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T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., & Novella, P. (2020). Simultaneous measurement of the muon neutrino charged-current cross section on oxygen and carbon without pions in the final state at T2K. Phys. Rev. D, 101(11), 112004–32pp.
Abstract: This paper reports the first simultaneous measurement of the double differential muon neutrino chargedcurrent cross section on oxygen and carbon without pions in the final state as a function of the outgoing muon kinematics, made at the ND280 off-axis near detector of the T2K experiment. The ratio of the oxygen and carbon cross sections is also provided to help validate various models' ability to extrapolate between carbon and oxygen nuclear targets, as is required in T2K oscillation analyses. The data are taken using a neutrino beam with an energy spectrum peaked at 0.6 GeV. The extracted measurement is compared with the prediction from different Monte Carlo neutrino-nucleus interaction event generators, showing particular model separation for very forward-going muons. Overall, of the models tested, the result is best described using local Fermi gas descriptions of the nuclear ground state with RPA suppression.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2021). Study of the reactions e(+)e(-)-> pi(+) pi(-) pi(0)pi(0)pi(0)pi(0) and pi(+) pi(-) pi(0)pi(0)pi(0)eta at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation. Phys. Rev. D, 104(11), 112004–19pp.
Abstract: We study the processes e(+)e(-) -> pi+ pi-pi(0)pi(0)pi(0)pi(0)gamma and pi(+) pi(-) pi(0)pi(0)pi eta gamma in which an energetic photon is radiated from the initial state. The data were collected with the BABAR detector at the SLAC National Accelerator Laboratory. About 7300 and 870 events, respectively, are selected from a data sample corresponding to an integrated luminosity of 469 fb(-1). The invariant mass of the hadronic final state defines the effective e(+)e(-) center-of-mass energy. The center-of-mass energies range from threshold to 4.5 GeV. From the mass spectra, the first ever measurements of the e(+)e(-) -> pi(+)pi(-) pi(0)pi(0)pi(0)pi(0) and the e(+)e(-) -> pi(+)pi(-) pi(0)pi(0)pi(0)eta cross sections are performed. The contributions from omega pi(0)pi(0)pi(0), eta pi(+)pi(-)pi(0), omega eta, and other intermediate states are presented. We observe the J=psi and psi(2S) in most of these final states and measure the corresponding branching fractions, many of them for the first time.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2020). Search for lepton-flavor-violating decays D-0 -> X(0)e(+/-)mu(-/+). Phys. Rev. D, 101(11), 112003–11pp.
Abstract: We present a search for seven lepton-flavor-violating neutral charm meson decays of the type D-0 -> X(0)e(+/-)mu(-/+), where X-0 represents a pi(0), K-S(0), (K) over bar*(0), rho(0), phi, omega, or eta meson. The analysis is based on 468 fb(-1) of e(+)e(-) annihilation data collected at or close to the Upsilon(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signals are observed, and we establish 90% confidence level upper limits on the branching fractions in the range (5.0-22.5) x 10(-7). The limits are between 1 and 2 orders of magnitude more stringent than previous measurements.
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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. (2020). Amplitude analysis of the B+ -> D+D-K+ decay. Phys. Rev. D, 102(11), 112003–32pp.
Abstract: Results are reported from an amplitude analysis of the B+ -> D+D-K+ decay. The analysis is carried out using LHCb proton-proton collision data taken at root s = 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb(-1). In order to obtain a good description of the data, it is found to be necessary to include new spin-0 and spin-1 resonances in the D-K+ channel with masses around 2.9 GeV/c(2), and a new spin-0 charmonium resonance in proximity to the spin-2 chi(c2)(3930) state.
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ATLAS Collaboration(Aad, G. et al), Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., Castillo Gimenez, V., et al. (2021). Search for trilepton resonances from chargino and neutralino pair production in root s=13 TeV pp collisions with the ATLAS detector. Phys. Rev. D, 103(11), 112003–37pp.
Abstract: A search is performed for the electroweak pair production of charginos and associated production of a chargino and neutralino, each of which decays through an R-parity-violating coupling into a lepton and a W, Z, or Higgs boson. The trilepton invariant-mass spectrum is constructed from events with three or more leptons, targeting chargino decays that include an electron or muon and a leptonically decaying Z boson. The analyzed dataset corresponds to an integrated luminosity of 139 fb(-1) of proton-proton collision data produced by the Large Hadron Collider at a center-of-mass energy of root s = 13 TeV and collected by the ATLAS experiment between 2015 and 2018. The data are found to be consistent with predictions from the Standard Model. The results are interpreted as limits at 95% confidence level on model-independent cross sections for processes beyond the Standard Model. Limits are also set on the production of charginos and neutralinos for a minimal supersymmetric Standard Model with an approximate B – L symmetry. Charginos and neutralinos with masses between 100 and 1100 GeV are excluded depending on the assumed decay branching fractions into a lepton (electron, muon, or tau lepton) plus a boson (W, Z, or Higgs).
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2021). Study of the process e(+) e(-) -> pi(+)pi (-) pi(0) using initial state radiation with BABAR. Phys. Rev. D, 104(11), 112003–31pp.
Abstract: The process e(+)e(-) -> pi(+) pi(-) pi(0)gamma is studied at a center-of-mass energy near the Upsilon(4S) resonance using a data sample of 469 fb(-1) collected with the BABAR detector at the PEP-II collider. We have performed a precise measurement of the e(+)e(-) -> pi(+) pi(-) pi(0) cross section in the center-of-mass energy range from 0.62 to 3.5 GeV. In the energy regions of the omega and phi resonances, the cross section is measured with a systematic uncertainty of 1.3%. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured e(+) e(-) -> pi(+) pi(-) pi(0) cross section from threshold to 2.0 GeV is (45.86 +/- 0.14 +/- 0.58) x 10(-10). From the fit to the measured 3 pi mass spectrum we have determined the resonance parameters Gamma(omega -> e(+)e(-)) B(omega -> pi(+) pi- pi(0)) = (0.5698 +/- 0.0031 +/- 0.0082) keV, Gamma(phi -> e(+)e(-)) B(phi -> pi(+) pi(-)pi(0)) = (0.1841 +/- 0.0021 +/- 0.0080) keV, and B(rho -> 3 pi) = (0.88 +/- 0.23 +/- 0.30) x 10(-4). The significance of the rho -> 3 pi signal is greater than 6 sigma. For the J/psi resonance we have measured the product Gamma(J/psi -> e(+) e(-)) B (J/psi -> 3 pi) = (0.1248 +/- 0.0019 +/- 0.0026) keV.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2018). Measurement of the gamma*gamma* -> eta ' transition form factor. Phys. Rev. D, 98(11), 112002–11pp.
Abstract: We study the process e(+)e(-) -> e(+)e(-)eta' in the double-tag mode and measure for the first time the gamma*gamma* -> eta' transition form factor F-eta'(Q(1)(2), Q(2)(2)) in the momentum-transfer range 2 < Q(1)(2), Q(2)(2) < 60 GeV2. The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb(-1) collected at the PEP-II e(+)e(-) collider with the BABAR detector at center-of-mass energies near 10.6 GeV.
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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. (2017). Observation of the Doubly Charmed Baryon Xi(++)(cc). Phys. Rev. Lett., 119(11), 112001–10pp.
Abstract: A highly significant structure is observed in the Lambda K-+(c)-pi(+)pi(+) mass spectrum, where the Lambda(+)(c) baryon is reconstructed in the decay mode pK(-)pi(+). The structure is consistent with originating from a weakly decaying particle, identified as the doubly charmed baryon Xi(++)(cc). The difference between the masses of the Xi(++)(cc) and Lambda(+)(c) states is measured to be 1334.94 +/- 0.72(stat.) +/- 0.27(syst.) MeV/c(2), and the Xi(++)(cc) mass is then determined to be 3621.40 +/- 0.72(stat.) +/- 0.27(syst.) +/- 0.14(Lambda(+)(c)) MeV/c(2), where the last uncertainty is due to the limited knowledge of the Lambda(+)(c) mass. The state is observed in a sample of proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb(-1), and confirmed in an additional sample of data collected at 8 TeV.
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