Antusch, S., Figueroa, D. G., Marschall, K., & Torrenti, F. (2020). Energy distribution and equation of state of the early Universe: Matching the end of inflation and the onset of radiation domination. Phys. Lett. B, 811, 135888–7pp.
Abstract: We study the energy distribution and equation of state of the universe between the end of inflation and the onset of radiation domination (RD), considering observationally consistent single-field inflationary scenarios, with a potential 'flattening' at large field values, and a monomial shape V(phi) proportional to vertical bar phi vertical bar(p) around the origin. As a proxy for (p)reheating, we include a quadratic interaction g(2)phi X-2(2) between the inflaton phi and a light scalar 'daughter' field X, with g(2) > 0. We capture the non-perturbative and non-linear nature of the system dynamics with lattice simulations, obtaining that: i) the final energy transferred to X depends only on p, not on g(2); ii) the final transfer of energy is always negligible for 2 <= p < 4, and of order similar to 50% for p >= 4; iii) the system goes at late times to matter-domination for p = 2, and always to RD for p > 2. In the latter case we calculate the number of e-folds until RD, significantly reducing the uncertainty in the inflationary observables Tl-s and r.
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Godbole, R. M., Maharathy, S. P., Mandal, S., Mitra, M., & Sinha, N. (2021). Interference effect in lepton number violating and conserving meson decays for a left-right symmetric model. Phys. Rev. D, 104(9), 095009–22pp.
Abstract: We study the effect of interference on the lepton number violating (LNV) and lepton number conserving (LNC) three-bodymeson decaysM(1)(+)-> l(i) (+) l(j)(+)pi(+/-) that arise in a TeV-scale left-right symmetric model (LRSM) with degenerate or nearly degenerate right-handed (RH) neutrinos. The LRSM contains three RH neutrinos and a RH gauge boson. The RH neutrinos with masses in the range of M-N similar to (MeV-few GeV) can give resonant enhancement in the semileptonic LNV and LNC meson decays. In the case where only one RH neutrino contributes to these decays, the predicted new physics branching ratios of semileptonic LNV and LNC meson decaysM(1)(+)-> l(i)(+) l(j)(+) pi(-) andM(+) 1 -> l(i)(+)l(j)(-) pi(+) are equal. We find that with at least two RH neutrinos contributing to the process, the LNV and LNC decay rates can differ. Depending on the neutrino mixing angles and CP-violating phases, the branching ratios of LNVand LNC decay channelsmediated by the heavy neutrinos can be either enhanced or suppressed, and the ratio of these two rates can differ from unity.
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Coppola, M., Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2020). Magnetic field driven enhancement of the weak decay width of charged pions. J. High Energy Phys., 09(9), 058–19pp.
Abstract: We study the effect of a uniform magnetic field B on the decays pi- > l- nu_l bar, where l(-)=e(-), μ(-), carrying out a general analysis that includes four pi (-) decay constants. Taking the values of these constants from a chiral effective Nambu-Jona-Lasinio (NJL) model, it is seen that the total decay rate gets strongly increased with respect to the B = 0 case, with an enhancement factor ranging from similar to 10 for eB = 0.1 GeV2 up to similar to 10(3) for eB = 1 GeV2. The ratio between electronic and muonic decays gets also enhanced, reaching a value of about 1 : 2 for eB = 1 GeV2. In addition, we find that for large B the angular distribution of outgoing antineutrinos shows a significant suppression in the direction of the magnetic field.
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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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Liang, W. H., Ban, T., & Oset, E. (2024). B0 → K(*)0X, B- K(*) -X, Bs-η(η1;φ)X from the X(3872) molecular perspective. Phys. Rev. D, 109(5), 054030–9pp.
Abstract: We study the decays B over bar 0 – over bar K0X, B- – K-X, B over bar 0s – eta(eta 1)X, B over bar 0 – over bar K*0X, B- – K*-X, B over bar 0s – phi X, with X equivalent to X(3872), from the perspective of the X(3872) being a molecular state made from the interaction of the D*+D-; D*0 over bar D0, and c:c: components. We consider both the external and internal emission decay mechanisms and find an explanation for the over bar K0X and K-X production rates, based on the mass difference of the charged and neutral D*D over bar components. We also find that the internal and external emission mechanisms add constructively in the B over bar 0 – over bar K0X, B- – K-X reactions, while they add destructively in the case of widths of the present measurements and allows us to make predictions for the unmeasured modes of B over bar 0s – eta(eta 1)X(3872) and B- – K*-X(3872). The future measurement of these decay modes will help us get a better perspective on the nature of the X(3872) and the mechanisms present in production reactions of that state. B over bar 0 – over bar K*0X, B- – K*-X reactions. This feature explains the decay
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