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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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Du, M. L., Guo, Z. H., & Oller, J. A. (2021). Insights into the nature of the P-cs(4459). Phys. Rev. D, 104(11), 114034–14pp.
Abstract: We study the nature of the recently observed Pcs(4459) by the LHCb collaboration by employing three methods based on the elastic effective-range expansion and the resulting size of the effective-range, the saturation of the compositeness relation and width of the resonance, and a direct fit to data involving the channels J/psi Lambda, Xi ' c over line D, and Xi c over line D*. We have also considered the addition of a Castillejo-Dalitz-Dyson (CDD) pole but this scenario can be discarded. Our different analyses clearly indicate the molecular nature of the Pcs(4459) with a clear Xi c over line D* dominant component. In relation with heavy-quark-spin symmetry our results also favor the actual existence of two resonances with J=1/2 (the lighter one) and 3/2 (the heavier one) in the energy region of the Pcs(4459). In the scenario of two-resonance for the Pcs(4459), the inclusion of the Xi ' c over line D channel is required for their mass splitting and it allows one to determine the spin structures of the two resonances.
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LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). Search for time-dependent CP violation in D-0 -> K+K- and D-0 -> pi(+)pi(-) decays. Phys. Rev. D, 104(7), 072010–23pp.
Abstract: A search for time-dependent violation of the charge-parity symmetry in D-0 -> K+K- and D-0 -> pi(+)pi(-) decays is performed at the LHCb experiment using proton-proton collision data recorded from 2015 to 2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb(-1). The D-0 meson is required to originate from a D*(2010)(+) -> D-0 pi(+) decay, such that its flavor at production is identified by the charge of the accompanying pion. The slope of the time-dependent asymmetry of the decay rates of D-0 and (D) over bar (0) mesons into the final states under consideration is measured to be Delta YK+K- = (-2.3 +/- 1.5 +/- 0.3) x 10(-40), Delta Y pi(+)pi(-) = (-4.0 +/- 2.8 +/- 0.4) x 10(-4), where the first uncertainties are statistical and the second are systematic. These results are compatible with the conservation of the charge-parity symmetry at the level of 2 standard deviations and improve the precision by nearly a factor of 2.
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Bruschini, R., & Gonzalez, P. (2021). Coupled-channel meson-meson scattering in the diabatic framework. Phys. Rev. D, 104(7), 074025–16pp.
Abstract: We apply the diabatic framework, a QCD-based formalism for the unified study of quarkoniumlike systems in terms of heavy quark-antiquark and open-flavor meson-meson components, to the description of coupled-channel meson-meson scattering. For this purpose, we first introduce a numerical scheme to find the solutions of the diabatic Schrodinger equation for energies in the continuum, then we derive a general formula for calculating the meson-meson scattering amplitudes from these solutions. We thus obtain a completely nonperturbative procedure for the calculation of open-flavor meson-meson scattering cross sections from the diabatic potential, which is directly connected to lattice QCD calculations. A comprehensive analysis of various elastic cross sections for open-charm and open-bottom meson-meson pairs is performed in a wide range of the center-of-mass energies. The relevant structures are identified, showing a spectrum of quasiconventional and unconventional quarkoniumlike states. In addition to the customary Breit-Wigner peaks, we obtain nontrivial structures such as threshold cusps and minimums. Finally, our results are compared with existing data and with results from our previous bound-state-based analysis, finding full compatibility with both.
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Forero, D. V., Giunti, C., Ternes, C. A., & Tortola, M. (2021). Nonunitary neutrino mixing in short and long-baseline experiments. Phys. Rev. D, 104(7), 075030–11pp.
Abstract: Nonunitary neutrino mixing in the light neutrino sector is a direct consequence of type-I seesaw neutrino mass models. In these models, light neutrino mixing is described by a submatrix of the full lepton mixing matrix and, then, it is not unitary in general. In consequence, neutrino oscillations are characterized by additional parameters, including new sources of CP violation. Here we perform a combined analysis of short and long-baseline neutrino oscillation data in this extended mixing scenario. We did not find a significant deviation from unitary mixing, and the complementary data sets have been used to constrain the nonunitarity parameters. We have also found that the T2K and NOvA tension in the determination of the Dirac CP-phase is not alleviated in the context of nonunitary neutrino mixing.
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Horak, J., Papavassiliou, J., Pawlowski, J. M., & Wink, N. (2021). Ghost spectral function from the spectral Dyson-Schwinger equation. Phys. Rev. D, 104(7), 074017–16pp.
Abstract: We compute the ghost spectral function in Yang-Mills theory by solving the corresponding Dyson-Schwinger equation for a given input gluon spectral function. The results encompass both scaling and decoupling solutions for the gluon propagator input. The resulting ghost spectral function displays a particle peak at vanishing momentum and a negative scattering spectrum, whose infrared and ultraviolet tails are obtained analytically. The ghost dressing function is computed in the entire complex plane, and its salient features are identified and discussed.
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Rosa, J. L., Lobo, F. S. N., & Olmo, G. J. (2021). Weak-field regime of the generalized hybrid metric-Palatini gravity. Phys. Rev. D, 104(12), 124030–11pp.
Abstract: In this work we explore the dynamics of the generalized hybrid metric-Palatini theory of gravity in the weak-field, slow-motion regime. We start by introducing the equivalent scalar-tensor representation of the theory, which contains two scalar degrees of freedom, and perform a conformal transformation to the Einstein frame. Linear perturbations of the metric in a Minkowskian background are then studied for the metric and both scalar fields. The effective Newton constant and the PPN parameter. of the theory are extracted after transforming back to the (original) Jordan frame. Two particular cases where the general method ceases to be applicable are approached separately. A comparison of these results with observational constraints is then used to impose bounds on the masses and coupling constants of the scalar fields.
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LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). Observation of a new Xi(0)(b) state. Phys. Rev. D, 103(1), 012004–17pp.
Abstract: Using a proton-proton collision data sample collected by the LHCb experiment, corresponding to an integrated luminosity of 8.5 fb(-1), the observation of a new excited Xi(0)(b) resonance decaying to the Xi(-)(b)pi(+) final state is presented. The state, referred to as Xi(b) (6227)(0), has a measured mass and natural width of m(Xi(b)(6227)(0)) = 6227.1(-1.5)(+1.4) +/- 0.5 MeV and Gamma(Xi(b)(6227)(0)) = 18.6(-4.1)(+5.0) +/- 1.4 MeV, where the uncertainties are statistical and systematic. The production rate of the Xi(b)(6227)(0) state relative to that of the Xi(-)(b) baryon in the kinematic region 2 < eta < 5 and p(T) < 30 GeV is measured to be f(Xi b(6227)0)/f(Xi b)(-) B(Xi(b)(6227)(0) -> Xi(-)(b)pi(+)) = 0.045 +/- 0.008 +/- 0.004, where B(Xi(b)(6227)(0) -> Xi(-)(b)pi(+)) is the branching fraction of the decay, and f(Xi b(6227)0) and f(Xi b-) represent fragmentation fractions. Improved measurements of the mass and natural width of the previously observedf Xi(b)(6227)(-) state, along with the mass of the Xi(-)(b) baryon, are also reported. Both measurements are significantly more precise than, and consistent with, previously reported values.
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Linster, M., Lopez-Pavon, J., & Ziegler, R. (2021). Neutrino observables from a U(2) flavor symmetry. Phys. Rev. D, 103(1), 015020–9pp.
Abstract: We study the predictions for CP phases and absolute neutrino mass scale for broad classes of models with a U(2)-like flavor symmetry. For this purpose we consider the same special textures in neutrino and charged lepton mass matrices that are successful in the quark sector. While in the neutrino sector the U(2) structure enforces two texture zeros, the contribution of the charged lepton sector to the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix can be parametrized by two rotation angles. Restricting to the cases where at least one of these angles is small, we obtain three representative scenarios. In all scenarios we obtain a narrow prediction for the sum of neutrino masses in the range of 60-75 meV, possibly in the reach of upcoming galaxy survey experiments. All scenarios can be excluded if near-future experimental date provide evidence for either neutrinoless double-beta decay or inverted neutrino mass ordering.
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T2K Collaboration(Abe, K. et al), Antonova, M., & Cervera-Villanueva, A. (2021). T2K measurements of muon neutrino and antineutrino disappearance using 3.13 x 10(21) protons on target. Phys. Rev. D, 103(1), L011101–9pp.
Abstract: We report measurements by the T2K experiment of the parameters theta(23) and Delta m(32)(2), which govern the disappearance of muon neutrinos and antineutrinos in the three-flavor PMNS neutrino oscillation model at T2K's neutrino energy and propagation distance. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, muon-like events from each beam mode are used to measure these parameters separately for neutrino and antineutrino oscillations. Data taken from 1.49 x 10(21) protons on target (POT) in neutrino mode and 1.64 x 10(21) POT in antineutrino mode are used. The best-fit values obtained by T2K were sin(2)(theta(23)) = 0.51(-0.07)(+0.06) (0.43(-0.05)(+0.21)) and Delta m(32)(2) = 2.47(-0.09)(+0.08) (2.50(-0.13)(+0.18)) x 10(-3) eV(2)/c(4) for neutrinos (antineutrinos). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed. An analysis using an effective two-flavor neutrino oscillation model where the sine of the mixing angle is allowed to take nonphysical values larger than 1 is also performed to check the consistency of our data with the three-flavor model. Our data were found to be consistent with a physical value for the mixing angle.
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