Ikeno, N., Toledo, G., & Oset, E. (2023). Model independent analysis of femtoscopic correlation functions: An application to the D∗s0(2317). Phys. Lett. B, 847, 138281–6pp.
Abstract: We face the inverse problem of obtaining the interaction between coupled channels from the correlation functions of these channels. We apply the method to the interaction of the (DK+)-K-0, (D+K0), and D-s(+)eta channels, from where the D-s0(& lowast;)(2317) state emerges. We use synthetic data extracted from an interaction model based on the local hidden gauge approach and find that the inverse problem can determine the existence of a bound state of the system with a precision of about 20 MeV. At the same time, we can determine the isospin nature of the bound state and its compositeness in terms of the channels. Furthermore, we evaluate the scattering length and effective range of all three channels, as well as the couplings of the bound state found to all the components. Lastly, the size parameter of the source function, R, which in principle should be a magnitude provided by the experimental teams, can be obtained from a fit to the data with relatively high accuracy. These findings show the value of the correlation function to learn about the meson-meson interaction for systems which are difficult to access in other present facilities.
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Ikeno, N., Molina, R., & Oset, E. (2021). The Z(cs)(3985) as a threshold effect from the (D)over-bar(s)*D + (D)over-bar(s)D* interaction. Phys. Lett. B, 814, 136120–5pp.
Abstract: We study the e(+)e(-) -> K+(D-s*D--(0) + Ds-D*(0)) reaction recently measured at BESIII, from where a new Z(cs) state has been reported. We study the interaction of (D) over bar D-s* with the coupled channels J/psi K-, K*(-)eta(c), Ds-D*(0), D-s*D--(0) by means of an extension to the charm sector of the local hidden gauge approach. We find that the Ds-D*(0) + D-s*D--(0) combination couples to J/psi K- and K*(-)eta(c), but the Ds-D*(0 ) -D-s*D--(0) combination does not. The coupled channels help to build up strength in the Ds-D*(0) + D-s*D--(0) diagonal scattering matrix close to threshold and, although the interaction is not strong enough to produce a bound state or resonance, it is sufficient to produce a large accumulation of strength at the (D) over bar D-s* threshold in the e(+)e(-) -> K+(D-s*D--(0) + Ds-D*(0)) reaction in agreement with experiment.
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Horvat, S., Magas, V. K., Strottman, D. D., & Csernai, L. P. (2010). Entropy development in ideal relativistic fluid dynamics with the Bag Model equation of state. Phys. Lett. B, 692(4), 277–280.
Abstract: We consider an idealized situation where the Quark-Gluon Plasma (QGP) is described by a perfect, (3 + 1)-dimensional fluid dynamic model starting from an initial state and expanding until a final state where freeze-out and/or hadronization takes place. We study the entropy production with attention to effects of (i) numerical viscosity, (ii) late stages of flow where the Bag Constant and the partonic pressure are becoming similar, (iii) and the consequences of final freeze-out and constituent quark matter formation.
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Hirsch, M., Srivastava, R., & Valle, J. W. F. (2018). Can one ever prove that neutrinos are Dirac particles? Phys. Lett. B, 781, 302–305.
Abstract: According to the “Black Box” theorem the experimental confirmation of neutrinoless double beta decay (0 nu 2 beta) would imply that at least one of the neutrinos is a Majorana particle. However, a null 0 nu 2 beta signal cannot decide the nature of neutrinos, as it can be suppressed even for Majorana neutrinos. In this letter we argue that if the null 0 nu 2 beta decay signal is accompanied by a 0 nu 2 beta quadruple beta decay signal, then at least one neutrino should be a Dirac particle. This argument holds irrespective of the underlying processes leading to such decays.
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Hiller Blin, A. N., Ledwig, T., & Vicente Vacas, M. J. (2015). Chiral dynamics in the (gamma)over-right-arrowp -> p pi(0) reaction. Phys. Lett. B, 747, 217–222.
Abstract: We investigate the neutral pion photoproduction on the proton near threshold in covariant chiral perturbation theory with the explicit inclusion of A degrees of freedom. This channel is specially sensitive to chiral dynamics and the advent of very precise data from the Mainz microtron has shown the limits of the convergence of the chiral series for both the heavy baryon and the covariant approaches. We show that the inclusion of the Delta resonance substantially improves the convergence leading to a good agreement with data for a wider range of energies.
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Hidalgo-Duque, C., Nieves, J., Ozpineci, A., & Zamiralov, V. (2013). X(3872) and its partners in the heavy quark limit of QCD. Phys. Lett. B, 727(4-5), 432–437.
Abstract: In this Letter, we propose interpolating currents for the X(3872) resonance, and show that, in the heavy quark limit of QCD, the X(3872) state should have degenerate partners, independent of its internal structure. Magnitudes of possible I = 0 and I = 1 components of the X(3872) are also discussed.
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Hernandez, E., Vijande, J., Valcarce, A., & Richard, J. M. (2020). Spectroscopy, lifetime and decay modes of the T-bb(-) tetraquark. Phys. Lett. B, 800, 135073–9pp.
Abstract: We present the first full-fledged study of the flavor-exotic isoscalar T-bb(-) equivalent to bb (u) over bar(d) over bar tetraquark with spin and parity J(P) = 1(+). We report accurate solutions of the four-body problem in a quark model, characterizing the structure of the state as a function of the ratio M-Q/m(q) of the heavy to light quark masses. For such a standard constituent model, T-bb(-) lies approximately 150 MeV below the strong decay threshold B- (B) over bar*(0) and 105 MeV below the electromagnetic decay threshold B- (B) over bar (0)gamma. We evaluate the lifetime of T-bb(-), identifying the promising decay modes where the tetraquark might be looked for in future experiments. Its total decay width is Gamma approximate to 87 x 10(-15) GeV and therefore its lifetime tau approximate to 7.6 ps. The promising final states are B*(-) D*(+) l (v) over bar (l) and (B) over bar*(0) l (v) over bar (l) among the semileptonic decays, and B*(-) D*(+) D-s*(-), (B) over bar*(0) D*(0) D-s*(-), and B*(-) D*(+) rho(-) among the nonleptonic ones. The semileptonic decay to the isoscalar J(P) = 0(+) tetraquark T-bc(0) is also relevant but it is not found to be dominant. There is a broad consensus about the existence of this tetraquark, and its detection will validate our understanding of the low-energy realizations of Quantum Chromodynamics (QCD) in the multiquark sector.
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Hernandez, E., Nieves, J., Sanchez, F., & Sobczyk, J. E. (2022). Tau longitudinal and transverse polarizations from visible kinematics in (anti-)neutrino nucleus scattering. Phys. Lett. B, 829, 137046–9pp.
Abstract: Since the upsilon(tau) ((upsilon) over bar (tau))A(Z) -> tau(-/+) X reaction is notoriously difficult to be directly measured, the information on the dynamics of this nuclear process should be extracted from the analysis of the energy and angular distributions of the tau decay visible products. These distributions depend, in addition to d(2)sigma / (dE(tau)d cos theta(tau)), on the components of the tau-polarization vector. We give, for the first time, the general expression for the outgoing hadron (pion or rho meson) energy and angular differential cross section for the sequential upsilon(tau) A(Z) -> tau(-) (pi(-)upsilon(tau,) rho(-)upsilon(tau))X and (upsilon) over bar (tau)A(Z) -> tau(+) (pi(+)(upsilon) over bar (tau), rho(+)(upsilon) over bar (tau)) X reactions. Though all possible nuclear reaction mechanisms contribute to the distribution, it may be possible to isolate/enhance one of them by implementing appropriate selection criteria. For the case of the quasi-elastic reaction off oxygen and neutrino energies below 6 GeV, we show that the pion distributions are quite sensitive to the details of the tau-polarization components. We find significant differences between the full calculation, where the longitudinal and transverse components of the tau polarization vector vary with the energy and the scattering angle of the produced tau, and the simplified scheme in which the polarizations are set to one and zero, being the latter their respective asymptotic values reached in the high energy regime. In addition to its potential impact on neutrino oscillation analyses, this result can be used to further test different nuclear models, since these observables provide complementary information to that obtained by means of the inclusive nuclear weak charged-current differential cross section. We also study the effects on the cross section of the W-4 and W-5 nuclear structure functions, which contributions are proportional to the charged lepton mass, and therefore difficult to constrain in muon and electron neutrino experiments.
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Han, X. F., Wang, L., & Yang, J. M. (2016). An extension of two-Higgs-doublet model and the excesses of 750 GeV diphoton, muon g-2 and h -> μτ. Phys. Lett. B, 757, 537–547.
Abstract: In this paper we simultaneously explain the excesses of the 750 GeV diphoton, muon g-2 and h -> μtau in an extension of the two-Higgs-doublet model (2HDM) with additional vector-like fermions and a CP-odd scalar singlet (P) which is identified as the 750 GeV resonance. This 750 GeV resonance has a mixing with the CP-odd scalar (A) from a second scalar doublet, which leads to a coupling between P and the SM particles as well as a coupling between A and the vector-like fermions. Such mixing and couplings are strongly constrained by tau -> μgamma, muon g-2 and the 750 GeV diphoton data. We scan over the parameter space and find that such an extension can simultaneously account for the observed excesses of 750 GeV diphoton, muon g-2 and h -> μtau. The 750 GeV resonance decays in exotic modes, such as P -> hA, P -> H Z, P -> H A and P -> W-+/- H--/+ and its width can be dozens of GeV and is sensitive to the mixing angle.
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Han, X. F., Wang, L., Wu, L., Yang, J. M., & Zhang, M. C. (2016). Explaining 750 GeV diphoton excess from top/bottom partner cascade decay in two-Higgs-doublet model extension. Phys. Lett. B, 756, 309–316.
Abstract: In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu extension of the two-Higgs-doublet model by introducing a top partner (T)/bottom partner (B). In the alignment limit, the 750 GeV resonance is identified as the heavy CP-even Higgs boson (H), which can be sizably produced via the QCD process pp -> T (T) over bar or pp -> B (B) over bar followed by the decay T -> Ht or B -> Hb. The diphoton decay rate of His greatly enhanced by the charged singlet scalars predicted in the Zee-Babu extension and the total width of H can be as large as 7 GeV. Under the current LHC constraints, we scan the parameter space and find that such an extension can account for the observed diphoton excess.
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