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Wimmer, K. et al, Algora, A., & Rubio, B. (2021). Shape Changes in the Mirror Nuclei Kr-70 and Se-70. Phys. Rev. Lett., 126(7), 072501–6pp.
Abstract: We studied the proton-rich T-z = -1 nucleus Kr-70 through inelastic scattering at intermediate energies in order to extract the reduced transition probability, B(E2; 0+ -> 2+). Comparison with the other members of the A = 70 isospin triplet, Br-70 and Se-70, studied in the same experiment, shows a 3 sigma deviation from the expected linearity of the electromagnetic matrix elements as a function of T-z. At present, no established nuclear structure theory can describe this observed deviation quantitatively. This is the first violation of isospin symmetry at this level observed in the transition matrix elements. A heuristic approach may explain the anomaly by a shape change between the mirror nuclei Kr-70 and Se-70 contrary to the model predictions.
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Roca, L., Liang, W. H., & Oset, E. (2022). Inconsistency of the data on the K-1(1270) -> pi K-0*(1430) decay width. Phys. Lett. B, 824, 136827–3pp.
Abstract: We show, using the same Lagrangian for the K-1(1270) -> pi K-0*(1430) and K-0*(1430) -> K-1 (1270)pi decays, that the present PDG data on the partial decay width of K-1 (1270) -> pi K-0*(1430) implies a width for K-0*(1430) -> K-1 (1270)pi decay which is about one order of magnitude larger than the total K-0*(1430) width. A discussion on this inconsistency is done, stressing its relationship to the existence of two K-1(1270) states obtained with the chiral unitary theory, which are not considered in the experimental analyses of K pi pi data.
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Bruschini, R., & Gonzalez, P. (2022). Is chi(c1)(3872) generated from string breaking? Phys. Rev. D, 105(5), 054028–6pp.
Abstract: We show, from a diabatic analysis of lattice results for string breaking, that mixing of Q (Q) over bar with open-flavor meson-meson configurations may be expressed through a mixing potential which is order 1/m(Q). A relation between the minimum string breaking energy gap and the string tension comes out naturally. Using this relation, and matching the energy gap for b (b) over bar with lattice QCD data, we study the mixing in the c (c) over bar case without any additional parameter. A 1(++) bound state very close below the D-0(D) over bar*(0) threshold, in perfect correspondence with chi(c1)(3872), is predicted.
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Maji, R., & Park, W. I. (2024). Supersymmetric U(1)B-L flat direction and NANOGrav 15 year data. J. Cosmol. Astropart. Phys., 01(1), 015–19pp.
Abstract: We show that, when connected with monopoles, the flat D-flat direction breaking the local U(1)B-L symmetry as an extension of the minimal supersymmetric standard model can be responsible for the signal of a stochastic gravitational wave background recently reported by NANOGrav collaborations, while naturally satisfying constraints at high frequency band. Thanks to the flatness of the direction, a phase of thermal inflation arises naturally. The reheating temperature is quite low, and suppresses signals at frequencies higher than the characteristic frequency set by the reheating temperature. Notably, forthcoming spaced based experiments such as LISA can probe the cutoff frequency, providing an indirect clue of the scale of soft SUSY-breaking mass parameter.
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Bordes, J., Hong-Mo, C., & Tsun, T. S. (2022). Resolving an ambiguity of Higgs couplings in the FSM, greatly improving thereby the model's predictive range and prospects. Int. J. Mod. Phys. A, 37(27), 2250167–10pp.
Abstract: We show that, after resolving what was thought to be an ambiguity in the Higgs coupling, the FSM gives, apart from two extra terms (i) and (ii) to be specified below, an effective action in the standard sector which has the same form as the SM action, the two differing only in the values of the mass and mixing parameters of quarks and leptons which the SM takes as Finputs from experiment while the FSM obtains as a result of a fit with a few parameters. Hence, to the accuracy that these two sets of parameters agree in value, and they do to a good extent as shown in earlier work,' the FSM should give the same result as the SM in all the circumstances where the latter has been successfully applied, except for the noted modifications due to (i) and (ii). If so, it would be a big step forward for the FSM. The correction terms are: (i) a mixing between the SM's gamma – Z with a new vector boson in the hidden sector, (ii) a mixing between the standard Higgs with a new scalar boson also in the hidden sector. And these have been shown a few years back to lead to (i') an enhancement of the W mass over the SM value,(2) – and (ii') effects consistent with the g – 2 and some other anomalies,(3) precisely the two deviations from the SM reported by experiments(4,5) recently much in the news.
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Oset, E., & Roca, L. (2018). Triangle mechanism in tau -> f(1)(1285)pi nu(tau) decay. Phys. Lett. B, 782, 332–338.
Abstract: We show that the tau(-) decay into f(1)(1285) pi(-)nu(tau) is dominated by a triangle loop mechanism with K*, (K) over bar* and K( or (K) over bar) as internal lines, which manifests a strong enhancement reminiscent of a nearby singularity present in the narrow K* limit and the near (K) over bar* K* threshold of the internal K* propagators. The f1(1285) is then produced by its coupling to the K* (K) over bar and (K) over bar* K which is obtained from a previous model where this resonance was dynamically generated as a molecular K* (K) over bar (or (K) over bar* K) state using the techniques of the chiral unitary approach. We make predictions for the f(1)pi mass distribution which significantly deviates from the phase-space shape, due to the distortion caused by the triangle mechanism and the K* (K) over bar threshold. We find a good agreement with the experimental value within uncertainties for the integrated partial decay width, which is a clear indication of the importance of the triangle mechanism in this decay and supports the dynamical origin of the f(1)(1285) as a K* (K) over bar and (K) over bar* K molecular state.
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Delhom, A., Lobo, I. P., Olmo, G. J., & Romero, C. (2020). Conformally invariant proper time with general non-metricity. Eur. Phys. J. C, 80(5), 415–11pp.
Abstract: We show that the definition of proper time for Weyl-invariant space-times given by Perlick naturally extends to spaces with arbitrary non-metricity. We then discuss the relation between this generalized proper time and the Ehlers-Pirani-Schild definition of time when there is arbitrary non-metricity. Then we show how this generalized proper time suffers from a second clock effect. Assuming that muons are a device to measure this proper time, we constrain the non-metricity tensor on Earth's surface and then elaborate on the feasibility of such assumption.
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Lazarides, G., Reig, M., Shafi, Q., Srivastava, R., & Valle, J. W. F. (2019). Spontaneous Breaking of Lepton Number and the Cosmological Domain Wall Problem. Phys. Rev. Lett., 122(15), 151301–5pp.
Abstract: We show that if global lepton number symmetry is spontaneously broken in a postinflation epoch, then it can lead to the formation of cosmological domain walls. This happens in the well-known “Majoron paradigm” for neutrino mass generation. We propose some realistic examples that allow spontaneous lepton number breaking to be safe from such domain walls.
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Reig, M., Valle, J. W. F., & Yamada, M. (2019). Light majoron cold dark matter from topological defects and the formation of boson stars. J. Cosmol. Astropart. Phys., 09(9), 029–25pp.
Abstract: We show that for a relatively light majoron (<< 100 eV) non-thermal production from topological defects is an efficient production mechanism. Taking the type I seesaw as benchmark scheme, we estimate the primordial majoron abundance and determine the required parameter choices where it can account for the observed cosmological dark matter. The latter is consistent with the scale of unification. Possible direct detection of light majorons with future experiments such as PTOLEMY and the formation of boson stars from the majoron dark matter are also discussed.
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Afonso, V. I., Olmo, G. J., Orazi, E., & Rubiera-Garcia, D. (2018). Mapping nonlinear gravity into General Relativity with nonlinear electrodynamics. Eur. Phys. J. C, 78(10), 866–11pp.
Abstract: We show that families of nonlinear gravity theories formulated in a metric-affine approach and coupled to a nonlinear theory of electrodynamics can be mapped into general relativity (GR) coupled to another nonlinear theory of electrodynamics. This allows to generate solutions of the former from those of the latter using purely algebraic transformations. This correspondence is explicitly illustrated with the Eddington-inspired Born-Infeld theory of gravity, for which we consider a family of nonlinear electrodynamics and show that, under the map, preserve their algebraic structure. For the particular case of Maxwell electrodynamics coupled to Born-Infeld gravity we find, via this correspondence, a Born-Infeld-type nonlinear electrodynamics on the GR side. Solving the spherically symmetric electrovacuum case for the latter, we show how the map provides directly the right solutions for the former. This procedure opens a new door to explore astrophysical and cosmological scenarios in nonlinear gravity theories by exploiting the full power of the analytical and numerical methods developed within the framework of GR.
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