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Valiente-Dobon, J. J. et al, Gadea, A., & Algora, A. (2021). Manifestation of the Berry phase in the atomic nucleus Pb-213. Phys. Lett. B, 816, 136183–5pp.
Abstract: The neutron-rich Pb-213 isotope was produced in the fragmentation of a primary 1 GeV A U-238 beam, separated in FRS in mass and atomic number, and then implanted for isomer decay gamma-ray spectroscopy with the RISING setup at GSI. A newly observed isomer and its measured decay properties indicate that states in Pb-213 are characterized by the seniority quantum number that counts the nucleons not in pairs coupled to angular momentum J = 0. The conservation of seniority is a consequence of a geometric phase associated with particle-hole conjugation, which becomes observable in semi-magic nuclei where nucleons half-fill the valence shell. The gamma-ray spectroscopic observables in Pb-213 are thus found to be driven by two mechanisms, particle-hole conjugation and seniority conservation, which are intertwined through a Berry phase.
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Bruschini, R., & Gonzalez, P. (2021). Diabatic description of charmoniumlike mesons. II. Mass corrections and strong decay widths. Phys. Rev. D, 103(7), 074009–13pp.
Abstract: From a diabatic bound state approach to J(PC) = 1(--) and (0,1,2)(++) charmoniumlike resonances below 4.1 GeV, formulated in terms of c (c) over bar and closed meson-meson channels, we calculate mass shifts and widths due to open meson-meson channels. This calculation does not involve any new free parameter, so comparison of our predictions with existing data provides a direct test of our approach. Further mass corrections are also estimated and good agreement with the measured masses comes out. As for the calculated widths, overall reasonable, they point out to the need of some refinement of our current bound state approximation for an accurate description of data. These results give additional support to the diabatic approach in QCD as an adequate framework for a complete unified description of conventional and unconventional charmoniumlike resonances. In this respect, the experimental discovery of a predicted 2(++) resonance with a mass around 4 GeV would be of special relevance.
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ATLAS Collaboration(Aad, G. et al), Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., Castillo Gimenez, V., et al. (2021). Longitudinal Flow Decorrelations in Xe plus Xe Collisions at root s(NN )=5.44 TeV with the ATLAS Detector. Phys. Rev. Lett., 126(12), 122301–20pp.
Abstract: The first measurement of longitudinal decorrelations of harmonic flow amplitudes v(n) for n = 2-4 in Xe + Xe collisions at root s(NN) = 5.44 TeV is obtained using 3 μb(-1) of data with the ATLAS detector at the LHC. The decorrelation signal for v(3) and v(4) is found to be nearly independent of collision centrality and transverse momentum (p(T)) requirements on fmal-state particles, but for v(2) a strong centrality and p(T) dependence is seen. When compared with the results from Pb + Pb collisions at. root s(NN) = 5.02 TcV, the longitudinal decorrelation signal in midcentral Xe + Xe collisions is found to be larger for v(2), but smaller for v(3). Current hydrodynamic models reproduce the ratios of the v(n) measured in Xe + Xe collisions to those in Pb + Pb collisions but fail to describe the magnitudes and trends of the ratios of longitudinal flow decorrelations between Xe + Xe and Pb + Pb. The results on the system-size dependence provide new insights and an important lever arm to separate effects of the longitudinal structure of the initial state from other early and late time effects in heavy-ion collisions.
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Gosta G. et al., & Gadea, A. (2021). Probing isospin mixing with the giant dipole resonance in the Zn-60 compound nucleus. Phys. Rev. C, 103(4), L041302–6pp.
Abstract: An experimental study of the isospin mixing in the mass region A = 60 was made by measuring the gamma decay from the giant dipole resonance in the compound nuclei Zn-60 and Zn-62. These compound nuclei were populated at two different excitation energies, E* = 47 MeV and E* = 58 MeV using the fusion evaporation reactions S-32 + Si-28 at the bombarding energy of 86 and 110 MeV and S-32 + Si-30 at 75 and 98 MeV. In the experiment, performed at the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare (INFN), the gamma rays were measured with the GALILEO detection system in which large-volume LaBr3(Ce) detectors were added to the HPGe detectors. The Coulomb spreading width was obtained from the comparison of the two reactions and then the isospin mixing parameter at zero temperature and the isospin-symmetry-breaking correction for beta decay were deduced. The present results were compared with data of the same type in other mass regions and with data from mass and beta-decay measurements and with theory. The present data allow us to deduce for the first time a consistent picture for mass dependence of isospin mixing and for the corresponding correction for the beta decay, supporting a reliable extension to the very interesting region of Sn-100.
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Dimitriou, P. et al, Tain, J. L., & Algora, A. (2021). Development of a Reference Database for Beta-Delayed Neutron Emission. Nucl. Data Sheets, 173, 144–238.
Abstract: Beta-delayed neutron emission is important for nuclear structure and astrophysics as well as for reactor applications. Significant advances in nuclear experimental techniques in the past two decades have led to a wealth of new measurements that remain to be incorporated in the databases. We report on a coordinated effort to compile and evaluate all the available beta-delayed neutron emission data. The different measurement techniques have been assessed and the data have been compared with semi-microscopic and microscopic-macroscopic models. The new microscopic database has been tested against aggregate total delayed neutron yields, time-dependent group parameters in 6-and 8-group re-presentation, and aggregate delayed neutron spectra. New recommendations of macroscopic delayed-neutron data for fissile materials of interest to applications are also presented.
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Das, A., & Mandal, S. (2021). Bounds on the triplet fermions in type-III seesaw and implications for collider searches. Nucl. Phys. B, 966, 115374–33pp.
Abstract: Type-III seesaw is a simple extension of the Standard Model (SM) with the SU(2)(L) triplet fermion with zero hypercharge. It can explain the origin of the tiny neutrino mass and flavor mixing. After the electroweak symmetry breaking the light neutrino mass is generated by the seesaw mechanism which further ensures the mixings between the light neutrino and heavy neutral lepton mass eigenstates. If the triplet fermions are around the electroweak scale having sizable mixings with the SM sector allowed by the correct gauge symmetry, they can be produced at the high energy colliders leaving a variety of characteristic signatures. Based on a simple and concrete realizations of the model we employ a general parametrization for the neutrino Dirac mass matrix and perform a parameter scan to identify the allowed regions satisfying the experimental constraints from the neutrino oscillation data, the electroweak precision measurements and the lepton-flavor violating processes, respectively considering the normal and inverted neutrino mass hierarchies. These parameter regions can be probed at the different collider experiments.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., et al. (2021). Measurement of the CP-violating phase phi(s) in B-s(0) -> J/psi phi decays in ATLAS at 13 TeV. Eur. Phys. J. C, 81(4), 342–36pp.
Abstract: A measurement of the B-0(s) -> J/psi phi decay parameters using 80.5 fb(-1) of integrated luminosity collected with the ATLAS detector from 13 TeV proton-proton collisions at the LHC is presented. The measured parameters include the CP-violating phase phi(s), the width difference Delta Gamma(s) between the B-s(0) meson mass eigenstates and the average decay width Gamma(s). The values measured for the physical parameters are combined with those from 19.2 fb(-1) of 7 and 8 TeV data, leading to the following: phi(s) = -0.087 +/- 0.036 (stat.) +/- 0.021 (syst.) rad Delta Gamma(s) = 0.0657 +/- 0.0043 (stat.) +/- 0.0037 (syst.) ps(-1) Gamma(s) = 0.6703 +/- 0.0014 (stat.) +/- 0.0018 (syst.) ps(-1) Results for phi(s) and Delta Gamma(s) are also presented as 68% confidence level contours in the phi(s)-Delta Gamma(s) plane. Furthermore the transversity amplitudes and corresponding strong phases are measured. phi(s) and Delta Gamma(s) measurements are in agreement with the Standard Model predictions.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2021). Study of the reactions e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0) and 2(pi(+)pi(-))pi(0)pi(0)eta at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation. Phys. Rev. D, 103(9), 092001–21pp.
Abstract: We study the processes e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0)gamma and 2(pi(+)pi(-))pi(0)pi(0)eta gamma in which an energetic photon is radiated from the initial state. The data were collected with the BABAR detector at SLAC. About 14 000 and 4700 events, respectively, are selected from a data sample corresponding to an integrated luminosity of 469 fb(-1). The invariant mass of the hadronic final state defines the effective e(+)e(-) center-of-mass energy. The center-of-mass energies range from threshold to 4.5 GeV. From the mass spectra, the first ever measurements of the e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0) and the e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)eta cross sections are performed. The contributions from omega pi(+)pi(-)pi(0)pi(0), eta 2(pi(+)pi(-)), and other intermediate states are presented. We observe the J/psi and psi(2S) in most of these final states and measure the corresponding branching fractions, many of them for the first time.
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Yang, Z., Cao, X., Guo, F. K., Nieves, J., & Pavon Valderrama, M. (2021). Strange molecular partners of the Z(c)(3900) and Z(c)(4020). Phys. Rev. D, 103(7), 074029–8pp.
Abstract: Quantum chromodynamics presents a series of exact and approximate symmetries which can be exploited to predict new hadrons from previously known ones. The Z(c)(3900) and Z(c)(4020), which have been theorized to be isovector D*(D) over bar and D*(D) over bar* molecules [I-G(J(PC)) = 1(-)(1)(+-))], are no exception. Here we argue that from SU(3)-flavor symmetry, we should expect the existence of strange partners of the Z(c)'s with hadronic molecular configurations D*(D) over bar (s) – D (D) over bar*(s) and D*(D) over bar*(s) (or, equivalently, quark content c (c) over bars (q) over bar, with q = u, d). The quantum numbers of these Z(cs) and Z(cs)* structures would be I(J(P)) = 1/2 (1(+)). The predicted masses of these partners depend on the details of the theoretical scheme used, but they should be around the D*(D) over bar (s) – D (D) over bar*(s) and D*(D) over bar*(s) thresholds, respectively. Moreover, any of these states could be either a virtual pole or a resonance. We show that, together with a possible triangle singularity contribution, such a picture nicely agrees with the very recent BESIII data of the e(+)e(-) -> K+((Ds-D*0) + D*D--(s)0).
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Boudet, S., Bombacigno, F., Montani, G., & Rinaldi, M. (2021). Superentropic black hole with Immirzi hair. Phys. Rev. D, 103(8), 084034–14pp.
Abstract: In the context of f(R) generalizations to the Hoist action, endowed with a dynamical Immirzi field, we derive an analytic solution describing asymptotically anti-de Sitter black holes with hyperbolic horizon. These exhibit a scalar hair of the second kind, which ultimately depends on the Immirzi field radial behavior. In particular, we show how the Immirzi field modifies the usual entropy law associated to the black hole. We also verify that the Immirzi field boils down to a constant value in the asymptotic region, thus restoring the standard loop quantum gravity picture. We finally prove the violation of the reverse isoperimetric inequality, resulting in the superentropic nature of the black hole, and we discuss in detail the thermodynamic stability of the solution.
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