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Feng, Y. C., Gil, F., Döring, M., Molina, R., Mai, M., Shastry, V., et al. (2024). Unitary coupled-channel three-body amplitude with pions and kaons. Phys. Rev. D, 110(9), 094002–21pp.
Abstract: Three-body dynamics above threshold is required for the reliable extraction of many amplitudes and resonances from experiment and lattice QCD. The S-matrix principle of unitarity can be used to construct dynamical coupled-channel approaches in which three particles scatter off each other, rearranging two-body subsystems by particle exchange. This paper reports the development of a three-body coupled-channel, amplitude including pions and kaons. The unequal-mass amplitude contains two-body S- and P-wave subsystems (“isobars”) of all isospins, I = 0, 1/2, 1,3/2, 2, and it also allows for transitions within a given isobar. The f 0 ( 500 )( 6 ) ,f 0 ( 980 ) , p ( 700 ) ,K * 0 ( 700 )( K ) , and K * ( 892 ) resonances are included, apart from repulsive isobars. Different methods to evaluate the amplitude for physical momenta are discussed. Production amplitudes for a 1 quantum numbers are shown as a proof of principle for the numerical implementation.
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Ardu, M., Hossain Rahat, M., Valori, N., & Vives, O. (2024). Electric Dipole Moments as indirect probes of dark sectors. J. High Energy Phys., 11(11), 049–25pp.
Abstract: Dark sectors provide beyond Standard Model scenarios which can address unresolved puzzles, such as the observed dark matter abundance or the baryon asymmetry of the Universe. A naturally small portal to the dark sector is obtained if dark-sector interactions stem from a non-Abelian hidden gauge group that couples through kinetic mixing with the hypercharge boson. In this work, we investigate the phenomenology of such a portal of dimension five in the presence of CP violation, focusing on its signatures in fermion electric dipole moments. We show that, currently unbounded regions of the parameter space from dark photon searches can be indirectly probed with upcoming electron dipole moment experiments for dark boson masses in the range 1 – 100 GeV. We also discuss two particular scenarios where a SU(2)D dark gauge group spontaneously breaks into either an Abelian U(1)D or nothing. In both cases, we show that potentially observable electron dipole moments can be produced in vast regions of the parameter space compatible with current experimental constraints and observed dark matter abundance.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2024). ATLAS Run 2 searches for electroweak production of supersymmetric particles interpreted within the pMSSM. J. High Energy Phys., 05(5), 106–57pp.
Abstract: A summary of the constraints from searches performed by the ATLAS collaboration for the electroweak production of charginos and neutralinos is presented. Results from eight separate ATLAS searches are considered, each using 140 fb(-1) of proton-proton data at a centre-of-mass energy of root s = 13TeV collected at the Large Hadron Collider during its second data-taking run. The results are interpreted in the context of the 19-parameter phenomenological minimal supersymmetric standard model, where R-parity conservation is assumed and the lightest supersymmetric particle is assumed to be the lightest neutralino. Constraints from previous electroweak, flavour and dark matter related measurements are also considered. The results are presented in terms of constraints on supersymmetric particle masses and are compared with limits from simplified models. Also shown is the impact of ATLAS searches on parameters such as the dark matter relic density and the spin-dependent and spin-independent scattering cross-sections targeted by direct dark matter detection experiments. The Higgs boson and Z boson 'funnel regions', where a low-mass neutralino would not oversaturate the dark matter relic abundance, are almost completely excluded by the considered constraints. Example spectra for non-excluded supersymmetric models with light charginos and neutralinos are also presented.
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Ge, Z. et al, & Ayet, S. (2024). High-precision measurements of the atomic mass and electron-capture decay Q value of 95 Tc. Phys. Lett. B, 859, 139094–9pp.
Abstract: A direct measurement of the ground-state-to-ground-state electron-capture decay Q value of 95 Tc has been performed utilizing the double Penning trap mass spectrometer JYFLTRAP. The Q value was determined to be 1695.92(13) keV by taking advantage of the high resolving power of the phase-imaging ion-cyclotron-resonance technique to resolve the low-lying isomeric state of 95 Tc (excitation energy of 38.910(40) keV) from the ground state. The mass excess of 95 Tc was measured to be -86015.95(18) keV/c2, exhibiting a precision of about 28 times higher and in agreement with the value from the newest Atomic Mass Evaluation (AME2020). Combined with the nuclear energy-level data for the decay-daughter 95 Mo, two potential ultra-low Q-value transitions are identified for future long-term neutrino-mass determination experiments. The atomic self-consistent many-electron Dirac- Hartree-Fock-Slater method and the nuclear shell model have been used to predict the partial half-lives and energy-release distributions for the two transitions. The dominant correction terms related to those processes are considered, including the exchange and overlap corrections, and the shake-up and shake-off effects. The normalized distribution of the released energy in the electron-capture decay of 95 Tc to excited states of 95 Mo is compared to that of 163 Ho currently being used for electron-neutrino-mass determination.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2024). Observation of Λb0 → Λc+ (D)over-bar(*)0 K- and Λb0 → Λc+ Ds*- decays. Eur. Phys. J. C, 84(6), 575–18pp.
Abstract: The decays Lambda(0)(b) -> Lambda(+)(c) (D) over bar (()*()0) K- and Lambda(0)(b) -> Lambda(+)(c) D-s*(-) are observed for the first time, in proton-proton collision data at root s = 13TeV, corresponding to an integrated luminosity of 5.4fb(-1) collected with the LHCb detector. Their ratios of branching fractions with respect to the Lambda(0)(b) -> Lambda(+)(c) D-s(-) mode are measured to be B(Lambda(0)(b) -> Lambda(+)(c) (D) over bar (0) K-)/B(Lambda(0)(b) -> Lambda(+)(c) D-s(-)) = 0.1908(-0.0034-0.0018)(+0.0036+0.0016) +/- 0.0038, B(Lambda(0)(b) -> Lambda(+)(c) (D) over bar*(0) K-)/B(Lambda(0)(b) -> Lambda(+)(c) D-s(-)) = 0.589(-0.017-0.018)(+0.018+0.017) +/- 0.012, B(Lambda(0)(b) -> Lambda(+)(c) D-s*(-))/B(Lambda(0)(b) -> Lambda(+)(c) D-s(-)) = 1.668 +/- 0.022(-0.055)(+0.061), where the first uncertainties are statistical, the second systematic, and the third, for the Lambda(0)(b) -> Lambda(+)(c) (D) over bar (()*()0) K- decays, are due to the uncertainties on the branching fractions of the D-s(-) -> K- K+ pi(-) and (D) over bar0 -> K+ pi(-) decay modes. The measured branching fractions probe factorization assumptions in effective theories and provide the normalization for future pentaquark searches in Lambda(0)(b) -> Lambda(+)(c) (D) over bar (()*()0) K- decay channels.
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