CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2011). Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from p p-bar Collisions at sqrt(s)=1.96 TeV. Phys. Rev. Lett., 107(3), 031801–8pp.
Abstract: We present the results of a search for a very light CP-odd Higgs boson a(1)(0) originating from top quark decays t -> H(+/-)b -> W(+/-(*)) a(1)(0)b, and subsequently decaying into tau(+)tau(-). Using a data sample corresponding to an integrated luminosity of 2.7 fb(-1) collected by the CDF II detector in p (p) over bar collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t -> H(+/-)b for various masses of H(+/-) and a(1)(0).
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2011). Search for a Heavy Toplike Quark in p p-bar Collisions at sqrt(s)=1.96 TeV. Phys. Rev. Lett., 107(26), 261801–8pp.
Abstract: We present the results of a search for pair production of a heavy toplike (t') quark decaying to Wq final states using data corresponding to an integrated luminosity of 5.6 fb(-1) collected by the CDF II detector in p (p) over bar collisions at root s = 1.96 TeV. We perform parallel searches for t' -> Wb and t' -> Wq (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t' quark mass, we set upper limits on the t'(t) over bar' production cross section and exclude a standard model fourth-generation t' quark decaying to Wb (Wq) with mass below 358 (340) GeV/c(2) at 95% C. L.
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CDF Collaboration(Aaltonen, T. et al), Cabrera, S., & Cuenca Almenar, C. (2010). Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events from p(p)over-bar Collisions at root s=1.96 TeV. Phys. Rev. Lett., 104(25), 251801–8pp.
Abstract: We present the results of a search for pair production of the supersymmetric partner of the top quark (the top squark (t) over tilde (1)) decaying to a b quark and a chargino (chi) over tilde (+/-)(1) with a subsequent (chi) over tilde (+/-)(1) decay into a neutralino (chi) over tilde (0)(1), lepton l, and neutrino nu Using a data sample corresponding to 2.7 fb(-1) of integrated luminosity of p (p) over bar collisions at root s = 1: 96 TeV collected by the CDF II detector, we reconstruct the mass of top squark candidate events and fit the observed mass spectrum to a combination of standard model processes and (t) over tilde (1)(t) over tilde (1). We find no evidence for (t) over tilde (1)(t) over tilde (1) production and set 95% C. L. limits on the masses of the top squark and the neutralino for several values of the chargino mass and the branching ratio B((X) over tilde (+/-)(1) -> (chi) over tilde (0)(1)l(+/-)nu).
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2010). Search for Supersymmetry with Gauge-Mediated Breaking in Diphoton Events with Missing Transverse Energy at CDF II. Phys. Rev. Lett., 104(1), 011801–8pp.
Abstract: We present the results of a search for supersymmetry with gauge-mediated breaking and (chi) over tilde (1)(0) -> gamma(G) over tilde in the gamma gamma + missing transverse energy final state. In 2.6 +/- 0.2 fb(-1) of p (p) over bar collisions at root s 1.96 TeV recorded by the CDF II detector we observe no candidate events, consistent with a standard model background expectation of 1.4 +/- 0.4 events. We set limits on the cross section at the 95% C.L. and place the world's best limit of 149 GeV/c(2) on the (chi) over tilde (1)(0) mass at tau((chi) over tilde 01) << 1 ns. We also exclude regions in the (chi) over tilde (1)(0) mass-lifetime plane for tau((chi) over tilde 01) less than or similar to 2 ns.
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Batra, A., Camara, H. B., Joaquim, F. R., Srivastava, R., & Valle, J. W. F. (2024). Axion Paradigm with Color-Mediated Neutrino Masses. Phys. Rev. Lett., 132(5), 051801–7pp.
Abstract: We propose a generalized Kim-Shifman-Vainshtein-Zakharov-type axion framework in which colored fermions and scalars act as two -loop Majorana neutrino -mass mediators. The global Peccei-Quinn symmetry under which exotic fermions are charged solves the strong CP problem. Within our general proposal, various setups can be distinguished by probing the axion-to-photon coupling at helioscopes and haloscopes. We also comment on axion dark -matter production in the early Universe.
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Bernabeu, J., & Segarra, A. (2018). Disentangling Genuine from Matter-Induced CP Violation in Neutrino Oscillations. Phys. Rev. Lett., 121(21), 211802–5pp.
Abstract: We prove that, in any flavor transition, neutrino oscillation CP-violating asymmetries in matter have two disentangled components: (i) a CPT-odd T-invariant term, non-vanishing iff there are interactions with matter, and (ii) a T-odd CPT-invariant term, non-vanishing iff there is genuine CP violation. As function of the baseline, these two terms are distinct L-even and L-odd observables to separately test (i) matter effects sensitive to the neutrino hierarchy and (ii) genuine CP violation in the neutrino sector. For the golden nu(mu) -> nu(e) channel, the different energy distributions of the two components provide a signature of their separation. At long baselines, they show oscillations in the low and medium energy regions, with zeros at different positions and peculiar behavior around the zeros. We discover a magic energy E = (0.91 +/- 0.01) GeV at L = 1300 km with vanishing CPT-odd component and maximal genuine CP asymmetry proportional to sin delta, with delta the weak CP phase. For energies above 1.5 GeV, the sign of the CP asymmetry discriminates the neutrino hierarchy.
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Husek, T., Goudzovski, E., & Icampf, K. (2019). Precise Determination of the Branching Ratio of the Neutral-Pion Dalitz Decay. Phys. Rev. Lett., 122(2), 022003–6pp.
Abstract: We provide a new value for the ratio R = Gamma(pi(0) -> e(+)e(-)gamma(gamma))/Gamma(pi(0) -> gamma gamma) = 11.978(6) x 10(-3), which is by 2 orders of magnitude more precise than the current Particle Data Group average. It is obtained using the complete set of the next-to-leading-order radiative corrections in the QED sector, and incorporates up-to-date values of the pi(0)-transition-form-factor slope. The ratio R translates into the branching ratios of the two main pi(0) decay modes: B(pi(0) -> gamma gamma) = 98.8131(6)% and B(pi(0) -> e(+)e(-)gamma(gamma)) = 1.1836(6)%.
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2011). Measurement of the Forward-Backward Asymmetry in the B -> K-(*) mu(+)mu(-) Decay and First Observation of the B-s(0) -> phi mu(+)mu(-) Decay. Phys. Rev. Lett., 106(16), 161801–7pp.
Abstract: We reconstruct the rare decays B+ -> K+ mu(+)mu(-), B-0 -> K*(892)(0) mu(+)mu(-), and B-s(0) -> phi(1020) mu(+)mu(-) in a data sample corresponding to 4.4 fb(-1) collected in p (p) over bar collisions at root s = 1.96 TeV by the CDF II detector at the Tevatron Collider. Using 121 +/- 16 B+ -> K+ mu(+)mu(-) and 101 +/- 12 B-0 -> K-*0 mu(+)mu(-) decays we report the branching ratios. In addition, we report the differential branching ratio and the muon forwardbackward asymmetry in the B+ and B-0 decay modes, and the K-*0 longitudinal polarization fraction in the B-0 decay mode with respect to the squared dimuon mass. These are consistent with the predictions, and most recent determinations from other experiments and of comparable accuracy. We also report the first observation of the B-s(0) -> phi mu(+)mu(-) decay and measure its branching ratio BR(B-s(0) -> phi mu(+)mu(-)) = [1.44 +/- 0.33 +/- 0.46] x 10(-6) using 27 +/- 6 signal events. This is currently the most rare B-s(0) decay observed.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Measurement of D-0-(D)over-bar(0) Mixing Parameters Using D-0 -> K-S(0)pi(+) pi(-) and D-0 -> (KSK+K-)-K-0 Decays. Phys. Rev. Lett., 105(8), 081803–7pp.
Abstract: We report a direct measurement of D-0-(D) over bar (0) mixing parameters through a time-dependent amplitude analysis of the Dalitz plots of D-0 -> K-S(0)pi(+)pi(-) and, for the first time, D-0 -> (KSK+K-)-K-0 decays. The low-momentum pion pi(+)(s) in the decay D*(+) -> D-0 pi(+)(s) identifies the flavor of the neutral D meson at its production. Using 468.5 fb(-1) of e(+)e(-) colliding-beam data recorded near root s = 10.6 by the BABAR detector at the PEP-II asymmetric-energy collider at SLAC, we measure the mixing parameters x = [1.6 + 2.3(stat) +/- 1.2(syst) +/- 0.8(model)] X 10(-3), and y = [5.7 +/- 2.0(stat) +/- 1.3(syst) +/- 0.7(model)] X 10(-3). These results provide the best measurement to date of x and y. The knowledge of the value of x, in particular, is crucial for understanding the origin of mixing.
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Belle II Collaboration(Abudinen, F. et al), & Marinas, C. (2021). Precise Measurement of the D-0 and D+ Lifetimes at Belle II. Phys. Rev. Lett., 127(21), 211801–9pp.
Abstract: We report a measurement of the D-0 and D+ lifetimes using D-0 -> K-pi(+) and D+ -> K-pi(+)pi(+) decays reconstructed in e(+)e(-) -> c (c) over bar data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy e(+)e(-) collider. The data, collected at center-of-mass energies at or near the (sic)(4S) resonance, correspond to an integrated luminosity of 72 fb(-1). The results, (tau)(D-0) = 410.5 +/- 1.1 (stat) +/- 0.8(syst) fs and tau(D-0) = 1030.4 +/- 4.7 (stat) +/- 3.1 (syst) fs, are the most precise to date and are consistent with previous determinations.
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