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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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Lu, J. N., Liu, X. G., & Ding, G. J. (2020). Modular symmetry origin of texture zeros and quark-lepton unification. Phys. Rev. D, 101(11), 115020–27pp.
Abstract: The even-weight modular forms of level N can be arranged into the common irreducible representations of the inhomogeneous finite modular group Gamma(N) and the homogeneous finite modular group Gamma(N)' which is the double covering of Gamma(N) , and the odd-weight modular forms of level N transform in the new representations of Gamma(N)'. We find that the above structure of modular forms can naturally generate texture zeros of the fermion mass matrices if we properly assign the representations and weights of the matter fields under the modular group. We perform a comprehensive analysis for the Gamma(3)' congruent to T' modular symmetry. The three generations of left-handed quarks are assumed to transform as a doublet and a singlet of T', and we find six possible texture-zero structures of the quark mass matrix up to row and column permutations. We present five benchmark quark models which can produce very good fits to the experimental data. These quark models are further extended to include the lepton sector, and the resulting models can give a unified description of both quark and lepton masses and flavor mixing simultaneously, although they contain a smaller number of free parameters than the observables.
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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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de Anda, F. J., Nath, N., Valle, J. W. F., & Vaquera-Araujo, C. A. (2020). Probing the predictions of an orbifold theory of flavor. Phys. Rev. D, 101(11), 116012–8pp.
Abstract: We examine the implications of a recently proposed theory of fermion masses and mixings in which an A(4) family symmetry emerges from orbifold compactification. We analyze two variant schemes concerning their predictions for neutrino oscillations, neutrinoless double-beta decay, and the golden quark-lepton unification mass relation. We find that upcoming experiments DUNE as well as LEGEND and nEXO offer good chances of exploring a substantial region of neutrino parameters.
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Mandal, S., Srivastava, R., & Valle, J. W. F. (2020). Consistency of the dynamical high-scale type-I seesaw mechanism. Phys. Rev. D, 101(11), 115030–15pp.
Abstract: We analyze the consistency of electroweak breaking within the simplest high-scale SU(3)(c) circle times SU(2)(L) circle times U(1)(Y) type-I seesaw mechanism. We derive the full two-loop renormalization group equations of the relevant parameters, including the quartic Higgs self-coupling of the Standard Model. For the simplest case of bare “right-handed” neutrino mass terms we find that, with large Yukawa couplings, the Higgs quartic self-coupling becomes negative much below the seesaw scale, so that the model may be inconsistent even as an effective theory. We show, however, that the “dynamical” type-I high-scale seesaw with spontaneous lepton number violation has better stability properties.
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Penalva, N., Hernandez, E., & Nieves, J. (2020). Hadron and lepton tensors in semileptonic decays including new physics. Phys. Rev. D, 101(11), 113004–24pp.
Abstract: We extend our general framework for semileptonic decay, originally introduced in N. Penalva et al. [Phys. Rev. D 100, 113007 (2019)], with the addition of new physics (NP) tensor terms. In this way, all the NP effective Hamiltonians that are considered in lepton flavor universality violation (LFUV) studies have now been included. Those are left and right vector and scalar NP Hamiltonians and the NP tensor one. Besides, we now also give general expressions that allow for complex Wilson coefficients. The scheme developed is totally general and it can be applied to any charged current semileptonic decay, involving any quark flavors or initial and final hadron states. We show that all the hadronic input, including NP effects, can be parametrized in terms of 16 Lorentz scalar structure functions, constructed out of the NP complex Wilson coefficients and the genuine hadronic responses, with the latter determined by the matrix elements of the involved hadron operators. In the second part of this work, we use this formalism to obtain the complete NP effects in the Ab Acr(/ semileptonic decay, where LFUV, if finally confirmed, is also expected to be seen. We- stress the relevance of the center of mass (CM) d2F/ (dwd cos 0i) and laboratory (LAB) d2F/(dwdE,) differential decay widths, with (o the product of the hadron four-velocities, Oe the angle made by the three -momenta of the charged lepton and the final hadron in the 11/- CM frame and the charged lepton energy in the decaying hadron rest frame. While models with very different strengths in the NP terms give the same differential d17 do) and total decay widths for this decay, they predict very different numerical results for some of the cos (.),, and E coefficient -functions that determine the above two distributions. Thus, the combined analysis of the CM d2F1(dcodcos0,,) and LAB d21'/(doidE,.) differential decay widths will help clarifying what kind of NP is a better candidate in order to explain LFUV.
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Nebot, M. (2020). Bounded masses in two Higgs doublets models, spontaneous CP violation and Z(2) symmetry. Phys. Rev. D, 102(11), 115002–16pp.
Abstract: In two Higgs doublet models (2HDMs) shaped by some unbroken symmetry, imposing perturbativity requirements on the quartic couplings can imply that the allowed masses of all the fundamental scalars are bounded from above. This important property is analyzed in detail for the only two realistic 2HDMs with an exact symmetry, the case with Z(2) symmetry and the case with CP symmetry. It is also noticeable that one exception arises in each case: when the vacuum is assumed to respect the imposed symmetry, a decoupling regime can nevertheless appear without violating perturbativity requirements. In both models with an exact symmetry and no decoupling regime, soft symmetry breaking terms can however lead to a decoupling regime: the possibility that this regime might be unnatural, since it requires some fine-tuning, is also analyzed.
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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). Measurement of the relative branching fractions of B+ -> h(+) h('+) h('-) decays. Phys. Rev. D, 102(11), 112010–19pp.
Abstract: The relative branching fractions of B+ -> h(+)h('+)h('-) decays, where h((')) is a pion or kaon, are measured. The analysis is performed with a data sample, collected with the LHCb detector, corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions. The results obtained improve significantly on previous measurements of these quantities, and are important for the interpretation of Dalitz plot analyses of three-body charmless hadronic decays of B+ mesons.
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Papoulias, D. K. (2020). COHERENT constraints after the COHERENT-2020 quenching factor measurement. Phys. Rev. D, 102(11), 113004–10pp.
Abstract: Recently, an improved quenching factor (QF) measurement for low-energy nuclear recoils in CsI[Na] has been reported by the COHERENT Collaboration. The new energy-dependent QF is characterized by a reduced systematic uncertainty and leads to a better agreement between the experimental COHERENT data and the Standard Model (SM) expectation. In this work, we report updated constraints on parameters that describe the process of coherent elastic neutrino-nucleus scattering within and beyond the SM, and we also present how the new QF affects their interpretation.
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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. (2020). Search for resonances decaying into a weak vector boson and a Higgs boson in the fully hadronic final state produced in proton – proton collisions at root s=13 TeV with the ATLAS detector. Phys. Rev. D, 102(11), 112008–27pp.
Abstract: A search for heavy resonances decaying into a W or Z boson and a Higgs boson produced in proton – proton collisions at the Large Hadron Collider at root s = 13 TeV is presented. The analysis utilizes the dominant W -> q (q) over bar' or Z -> q (q) over bar and H -> b (b) over bar decays with substructure techniques applied to large-radius jets. A sample corresponding to an integrated luminosity of 139 fb(-1) collected with the ATLAS detector is analyzed and no significant excess of data is observed over the background prediction. The results are interpreted in the context of the heavy vector triplet model with spin-1 W' and Z' bosons. Upper limits on the cross section are set for resonances with mass between 1.5 and 5.0 TeV, ranging from 6.8 to 0.53 fb for W' -> WH and from 8.7 to 0.53 fb for Z' -> ZH at the 95% confidence level.
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