Ikeno, N., Liang, W. H., & Oset, E. (2024). Molecular nature of the Ωc(3120) and its analogy with the Ω(2012). Phys. Rev. D, 109(5), 054023–7pp.
Abstract: We make a study of the omega c(3120) , one of the five omega c states observed by the LHCb Collaboration, which is well reproduced as a molecular state from the Xi*cK over bar and omega*c17 channels mostly. The state with JP = 3/2- decays to Xi cK over bar in the D wave, and we include this decay channel in our approach, as well as the effect of the Xi*c width. With all these ingredients, we determine the fraction of the omega c(3120) width that goes into Xi cK over bar K , which could be a measure of the Xi*cK over bar molecular component, but due to a relatively big binding, compared to its analogous omega(2012) state, we find only a small fraction of about 3%, which makes this measurement difficult with present statistics. As an alternative, we evaluate the scattering length and effective range of the Xi*c K over bar and omega*c17 channels, which, together with the binding and width of the omega c(3120) state, could give us an answer to the issue of the compositeness of this state when these magnitudes are determined experimentally, something feasible nowadays, for instance, measuring correlation functions.
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Ikeno, N., Dias, J. M., Liang, W. H., & Oset, E. (2019). chi(c1) decays into a pseudoscalar meson and a vector-vector molecule. Phys. Rev. D, 100(11), 114011–7pp.
Abstract: We evaluate ratios of the chi(c1) decay rates to eta (eta', K-) and one of the f(0) (1370), f(0) (1710), f(2) (1270), f(2)'(1525), K-2*(1430) resonances, which in the local hidden gauge approach are dynamically generated from the vector-vector interaction. With the simple assumption that the chi(c1) is a singlet of SU(3), and the input from the study of these resonances as vector-vector molecular states, we describe the experimental ratio B(chi(c1)-> eta f(2) (1270))/B(chi(c1) -> eta'f(2)' (1525)) and make predictions for six more ratios that can be tested in future experiments.
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Ikeno, N., Bayar, M., & Oset, E. (2023). Molecular states of D*D*Kbar* nature. Phys. Rev. D, 107(3), 034006–12pp.
Abstract: We study the interaction of two D* and a over bar K* by using the fixed center approximation to the Faddeev equations to search for bound states of the three-body system. Since the D*D* interaction is attractive and gives a bound state, and so is the case of the D* over bar K* interaction, where the JP = 0+ bound state is identified with the X0(2900), the D*D* over bar K* system leads to manifestly exotic bound states with ccs open quarks. We obtain bound states of isospin I = 1=2, negative parity and total spin J = 0, 1, 2. For J = 0 we obtain one state, and for J = 1, 2 we obtain two states in each case. The binding energies range from 56 to 152 MeV and the widths from 80 to 100 MeV.
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Ibañez, D., & Papavassiliou, J. (2013). Gluon mass generation in the massless bound-state formalism. Phys. Rev. D, 87(3), 034008–25pp.
Abstract: We present a detailed, all-order study of gluon mass generation within the massless bound-state formalism, which constitutes the general framework for the systematic implementation of the Schwinger mechanism in non-Abelian gauge theories. The main ingredient of this formalism is the dynamical formation of bound states with vanishing mass, which give rise to effective vertices containing massless poles; these latter vertices, in turn, trigger the Schwinger mechanism, and allow for the gauge-invariant generation of an effective gluon mass. This particular approach has the conceptual advantage of relating the gluon mass directly to quantities that are intrinsic to the bound-state formation itself, such as the “transition amplitude'' and the corresponding ”bound-state wave function.'' As a result, the dynamical evolution of the gluon mass is largely determined by a Bethe-Salpeter equation that controls the dynamics of the relevant wave function, rather than the Schwinger-Dyson equation of the gluon propagator, as happens in the standard treatment. The precise structure and field-theoretic properties of the transition amplitude are scrutinized in a variety of independent ways. In particular, a parallel study within the linear-covariant (Landau) gauge and the background-field method reveals that a powerful identity, known to be valid at the level of conventional Green's functions, also relates the background and quantum transition amplitudes. Despite the differences in the ingredients and terminology employed, the massless bound-state formalism is absolutely equivalent to the standard approach based on Schwinger-Dyson equations. In fact, a set of powerful relations allows one to demonstrate the exact coincidence of the integral equations governing the momentum evolution of the gluon mass in both frameworks.
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Huang, G. Y., Lindner, M., Martinez-Mirave, P., & Sen, M. (2022). Cosmology-friendly time-varying neutrino masses via the sterile neutrino portal. Phys. Rev. D, 106(3), 033004–18pp.
Abstract: We investigate a consistent scenario of time-varying neutrino masses, and discuss its impact on cosmology, beta decay, and neutrino oscillation experiments. Such time-varying masses are assumed to be generated by the coupling between a sterile neutrino and an ultralight scalar field, which in turn affects the light neutrinos by mixing. We demonstrate how various cosmological bounds, such as those coming from big bang nucleosynthesis, the cosmic microwave background, as well as large scale structures, can be evaded in this model. This scenario can be further constrained using multiple terrestrial experiments. In particular, for beta-decay experiments like KATRIN, nontrivial distortions to the electron spectrum can be induced, even when time-variation is fast and it gets averaged. Furthermore, the presence of time-varying masses of sterile neutrinos will alter the interpretation of light sterile neutrino parameter space in the context of the reactor and gallium anomalies. In addition, we also study the impact of such time-varying neutrino masses on results from the BEST collaboration, which have recently strengthened the gallium anomaly. If confirmed, we find that the time-varying neutrino mass hypothesis could give a better fit to the recent BEST data.
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Huang, F., Sanz, V., Shu, J., & Xue, X. (2021). LIGO as a probe of dark sectors. Phys. Rev. D, 104(10), 095001–9pp.
Abstract: We show how current LIGO data is able to probe interesting theories beyond the Standard Model, particularly dark sectors where a dark Higgs boson triggers symmetry breaking via a first-order phase transition. We use publicly available LIGO O2 data to illustrate how these sectors, even if disconnected from the Standard Model, can be probed by gravitational wave detectors. We link the LIGO measurements with the model content and mass scale of the dark sector, finding that current O2 data are testing a broad set of scenarios that can be mapped into many different types of dark-sector models where the breaking of SU(N) theories with Nf fermions is triggered by a dark Higgs boson at scales ? similar or equal to 108-109 GeV with reasonable parameters for the scalar potential.
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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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Hirsch, M., & Wang, Z. S. (2020). Heavy neutral leptons at ANUBIS. Phys. Rev. D, 101(5), 055034–9pp.
Abstract: Recently Bauer et al. [arXiv:1909.13022] proposed ANUBIS, an auxiliary detector to be installed in one of the shafts above the ATLAS or CMS interaction point, as a tool to search for long-lived particles. Here, we study the sensitivity of this proposal for long-lived heavy neutral leptons (HNLs) in both minimal and extended scenarios. We start with the minimal HNL model where both production and decay of the HNLs are mediated by active-sterile neutrino mixing, before studying the case of right-handed neutrinos in a leftright symmetric model. We then consider a U(1)(B-L) extension of the Standard Model (SM). In this model HNLs are produced from the decays of the mostly SM-like Higgs boson, via mixing in the scalar sector of the theory. In all cases, we fmd that ANUBIS has sensitivity reach comparable to the proposed MATHUSLA detector. For the minimal HNL scenario, the contributions from W's decaying to HNLs are more important at ANUBIS than at MATHUSLA, extending the sensitivity to slightly larger HNL masses at ANUBIS.
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Hirsch, M., Staub, F., & Vicente, A. (2012). Enhancing l(i) -> 3l(j) with the Z(0)-penguin. Phys. Rev. D, 85(11), 113013–5pp.
Abstract: Lepton flavor violation has been observed in neutrino oscillations. For charged lepton flavor violation decays only upper limits are known, but sizable branching ratios are expected in many neutrino mass models. High-scale models, such as the classical supersymmetric seesaw, usually predict that decays l(i) -> 3l(j) are roughly a factor alpha smaller than the corresponding decays l(i) -> l(j)gamma. Here we demonstrate that the Z(0)-penguin diagram can give an enhancement for decays l(i) -> 3l(j) in many extensions of the minimal supersymmetric standard model (MSSM). We first discuss why the Z(0)-penguin is not dominant in the MSSM with seesaw and show that much larger contributions from the Z(0)-penguin are expected in general. We then demonstrate the effect numerically in two example models, namely, the supersymmetric inverse seesaw and R-parity violating supersymmetry.
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Hirsch, M., Reichert, L., Porod, W., & Staub, F. (2012). Phenomenology of a supersymmetric U(1)(B-L) x U(1)(R) extension of the standard model with inverse seesaw mechanism. Phys. Rev. D, 86(9), 093018–26pp.
Abstract: We discuss the minimal supersymmetric U(1)(B-L) X U(1)(R) extension of the standard model. Gauge couplings unify as in the minimal supersymmetric standard model (MSSM), even if the scale of U(1)(B-L) X U(1)(R) breaking is as low as order TeV and the model can be embedded into a SO(10) grand unified theory. The phenomenology of the model differs in some important aspects from the MSSM, leading potentially to rich phenomenology at the LHC. It predicts more light Higgs states and the mostly left CP-even Higgs having a mass that easily reaches 125 GeV, with no constraints on the supersymmetry spectrum. Right sneutrinos can be the lightest supersymmetric particle, changing all dark matter constraints on supersymmetry parameter space. The model has seven neutralinos, and squark/gluino decay chains involve more complicated cascades than in the MSSM. We also briefly discuss low-energy and accelerator constraints on the model, where the most important limits come from recent Z' searches at the LHC and upper limits on lepton flavor violation.
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