Weak Decays Research Articles

The Λc → Λ ℓ+νℓ weak decay including new physics

We investigate the Λc → Λℓ+νℓ decay with a focus on potential new physics (NP) effects in the ℓ = μ channel. We employ an effective Hamiltonian within the framework of the Standard Model Effective Field Theory (SMEFT) to consider generalized dimension-6 semileptonic c → s operators of scalar, pseudoscalar, vector, axial-vector and tensor types. We rely on Lattice QCD (LQCD) for the hadronic transition form factors, using heavy quark spin symmetry (HQSS) to determine those that have not yet been obtained on the lattice. Uncertainties due to the truncation of the NP Hamiltonian and different implementations of HQSS are taken into account. As a result, we unravel the NP discovery potential of the Λc → Λ semileptonic decay in different observables. Our findings indicate high sensitivity to NP in lepton flavour universality ratios, probing multi-TeV scales in some cases. On the theoretical side, we identify LQCD uncertainties in axial and vector form factors as critical for improving NP sensitivity, alongside better SMEFT uncertainty estimations.

Strangeness production in sNN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s_{\ extrm{NN}}} $$\\end{document} = 3 GeV Au+Au collisions at RHIC

We report multi-differential measurements of strange hadron production ranging from mid- to target-rapidity in Au+Au collisions at a center-of-momentum energy per nucleon pair of sNN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s_{\ extrm{NN}}} $$\\end{document} = 3 GeV with the STAR experiment at RHIC. KS0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {K}_S^0 $$\\end{document} meson and Λ hyperon yields are measured via their weak decay channels. Collision centrality and rapidity dependences of the transverse momentum spectra and particle ratios are presented. Particle mass and centrality dependence of the average transverse momenta of Λ and KS0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {K}_S^0 $$\\end{document} are compared with other strange particles, providing evidence of the development of hadronic rescattering in such collisions. The 4π yields of each of these strange hadrons show a consistent centrality dependence. Discussions on radial flow, the strange hadron production mechanism, and properties of the medium created in such collisions are presented together with results from hadronic transport and thermal model calculations.

Isospin sum rules in charmed baryon weak decays

Isospin symmetry is the most precise flavor symmetry. The effective Hamiltonian of charm quark weak decay is zero under the isospin lowering operators I-n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$I_-^n$$\\end{document}, which permits us to generate isospin sum rules through several master formulas. In this work, we derive the master formulas of isospin sum rules for the two- and three-body non-leptonic decays of singly and doubly charmed baryons. Hundreds of isospin sum rules are derived to test of isospin symmetry and provide hints for the new decay modes. The isospin sum rules for multi-body decays are not broken by the intermediate resonances and hence can be used to study the isospin partners of exotic hadrons.

Isospin sum rules for the nonleptonic B decays

Isospin symmetry, as the most precise flavor symmetry, can be used to extract information about hadronic dynamics. The effective Hamiltonian for bottom quark weak decay is zero under the isospin lowering operators I-n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$I_-^n$$\\end{document}, which allows us to generate isospin sum rules through several master formulas. In this work, we derive the master formulas of isospin sum rules for the two- and three-body non-leptonic decays of B mesons. Numerous new isospin sum rules, especially those involving three or more decay channels, are proposed. The isospin sum rules can be used to test isospin symmetry and provide hints the isospin partners of exotic hadrons in B decays. It is found ten percent isospin breaking only in decay modes involving two vector mesons, indicating the complex dynamics of vector mesons. Besides, the isospin analysis suggests the charm tetraquark resonances might be observed in the B-→J/Ψπ-K¯0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ B^- \\rightarrow J/\\Psi \\pi ^-\\overline{K}^0$$\\end{document}, B¯0→J/ΨK¯0ϕ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\overline{B}^0 \\rightarrow J/\\Psi \\overline{K}^0\\phi $$\\end{document}, and B¯0→D0D¯0K¯0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\overline{B}^0\\rightarrow D^0\\overline{D}^0\\overline{K}^0$$\\end{document} modes.

Bc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varvec{B_c}$$\\end{document} to A transition form factors and semileptonic decays in self-consistent covariant light-front approach

We present a comprehensive analysis of the semileptonic weak decays of Bc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c$$\\end{document} meson decaying to axial-vector (A) mesons for bottom-conserving and bottom-changing decay modes. We employ self-consistent covariant light-front quark model (CLF QM) that uses type-II correspondence to eliminate inconsistencies in the traditional type-I CLF QM. As a fresh attempt, we test the self-consistency in CLF QM through type-II correspondence for Bc→A\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow A$$\\end{document} meson transition form factors. We establish that in type-II correspondence the form factors for longitudinal and transverse polarization states are numerically equal and are free from zero-mode contributions, which confirms the self-consistency of type-II correspondence for Bc→A\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow A$$\\end{document} transition form factors. Furthermore, we ascertain that the problems of inconsistency and violation of covariance of CLF QM within the type-I correspondence are resolved in type-II correspondence for Bc→A\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow A$$\\end{document} transitions. We thoroughly investigate the effects of self-consistency between type-I and type-II schemes using a comparative analysis. In this investigation, we employ a direct calculation approach to determine the form factors within the space-like region. Subsequently, we employ a vector meson dominance (VMD)-inspired three-parameter form to extrapolate these form factors into the physically accessible region. This enables us to study the q2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$q^2$$\\end{document} dependence of the form factors in weak hadronic currents for the whole accessible kinematic range for both bottom-conserving as well as bottom-changing transitions. In addition, we extend our analysis to predict the branching ratios of the semileptonic weak decays of Bc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c$$\\end{document} meson involving axial-vector meson in the final state to quantify the effects of self-consistency in these decays that were not studied before. We evaluate the lepton mass effect on these branching ratios and various other important physical observables, such as forward-backward asymmetries, lepton-side convexity parameter, asymmetry parameter, and longitudinal polarization asymmetries and fractions. Finally, we obtain the lepton flavor universality ratios for various decays.

Investigations of the weak decays of DB¯ molecules

The decays of exotic states discovered experimentally always proceed via the strong and electromagnetic interactions. Recently, a tetraquark state with the quark content bcq¯q¯ was predicted by lattice QCD simulations. It is below the mass threshold of DB¯, which can only decay via the weak interaction. In this work, based on the decay mechanism of Tcc as a DD* molecule, we propose that the decays of the bcq¯q¯ tertaquark state as a DB¯ molecule proceed via the Cabibbo-favored weak decays of the B¯ or D meson, accompanied by the tree-level decay modes and the triangle decay modes. Our results indicate that the branching fraction of the DB¯ molecule decaying into π+K−B¯0 is sizable, which is a good channel to observe the DB¯ molecule in future experiments. Published by the American Physical Society 2024

Hypernuclear constraints on the existence and lifetime of a deeply bound H dibaryon

We study to what extent the unique observation of ΛΛ hypernuclei by their weak decay into known Λ hypernuclei, with lifetimes of order 10−10 s, rules out the existence of a deeply bound doubly-strange (S = − 2) H dibaryon. Treating ΛΛ6He (the Nagara emulsion event) in a realistic Λ−Λ−4He three-body model, we find that the HeΛΛ6→H+4He strong-interaction lifetime increases beyond 10−10 s for mH<mΛ+mn, about 176 MeV below the ΛΛ threshold, so that such a deeply bound H is not in conflict with hypernuclear data. Constrained by Λ hypernuclear ΔS=1 nonmesonic weak-interaction decay rates, we follow EFT methods to evaluate the ΔS=2H→nn weak-decay lifetime of H in the mass range 2mn≲mH<mΛ+mn. The resulting H lifetime is of order 105 s, many orders of magnitude shorter than required to qualify for a dark-matter candidate.

Cascade Ξ0 baryon spectroscopy in the relativistic framework of an independent quark model

The spectroscopy of Ξ0 is performed within the relativistic framework of independent quark model. The equal mixture of scalar and vector components in the potential having Martin-like form is considered for the confinement. With the suitable potential parameters for Ξ0, mass spectra for high radial and orbital excitation is calculated. The experimentally observed values of the ground-state magnetic moment, branching ratios, and asymmetry parameters for radiative weak decays, Ξ0→Λ0+γ0 and Ξ0→Σ0+γ0 are obtained to validate the model. The spin parity of experimentally known resonances like Ξ(1530), Ξ(1820), and Ξ(2030) are confirmed through the Regge trajectories in (J,M2) plane. The spin parity of Ξ(1950), Ξ(2130), and Ξ(2250) are predicted using those Regge trajectories. The radiative decay width and magnetic moment of first resonance is also predicted. Published by the American Physical Society 2024

Production of pentaquarks with hidden charm and double strangeness in Ξb and Ωb decays

Recently, several pentaquark states Pcss, with global flavor c¯cssn, have been predicted within a theoretical framework based on unitary coupled channels. We study theoretically the feasibility to observe the Pcss with I(JP)=12(12−) in the decays Ξb0→ηηcΞ0 and Ωb−→K−ηcΞ0. Indeed, within the model, the ηcΞ0 channel is the lowest mass pseudoscalar-baryon channel to which this pentaquark state couples, thus we can expect to observe its signal in the ηcΞ0 invariant mass distribution of the mentioned decays. We identify the dominant weak decay processes and then implement the hadronization into the different meson-baryon channels in the final state, linked by flavor symmetry. The dominant meson-baryon final state interaction is then implemented to generate the full amplitude, implicitly accounting for the dynamical emergence of the pentaquark states. We obtain a clear Breit-Wigner-like resonant signal in the spectrum of the Ωb− decay, exceeding that in the Ξb0 decay by two to three orders of magnitude. In the case of the latter decay, the resonant state would manifest as a significant dip in the spectrum. We study the feasibility of searching for these b-hadron decay modes and analyzing their resonant components using the current and future data samples from the LHCb experiment. Published by the American Physical Society 2024

Study of the isoscalar scalar bcu¯d¯ tetraquark Tbc with lattice QCD

We present a lattice QCD study of the elastic S-wave DB¯ scattering in search of tetraquark candidates with explicitly exotic flavor content bcu¯d¯ in the isospin I=0 and JP=0+ channel. We use four lattice QCD ensembles with dynamical u/d, s, and c quark fields generated by the MILC collaboration. A nonrelativistic QCD Hamiltonian, including improvement coefficients up to O(αsv4), is utilized for the bottom quarks. For the rest of the valence quarks we employ a relativistic overlap action. Five different valence quark masses are utilized to study the light quark mass dependence of the DB¯ scattering amplitude. The finite volume energy spectra are extracted following a variational approach. The elastic DB¯ scattering amplitudes are extracted employing Lüscher’s prescription. The light quark mass dependence of the continuum extrapolated amplitudes suggests an attractive interaction between the B¯ and D mesons. At the physical pseudoscalar meson mass (Mps=Mπ) the DB¯ scattering amplitude has a subthreshold pole corresponding to a binding energy of −39(−6+4)(−18+8) MeV with respect to the DB¯ threshold. The critical Mps at which the DB¯ scattering length diverges and the system becomes unbound corresponds to Mps*=2.94(15)(5) GeV. This result can hold significant experimental relevance in the search for a bound scalar Tbc tetraquark, which could well be the next “doubly heavy” bound tetraquark to be discovered with only weak decay modes. Published by the American Physical Society 2024

Composite dark matter and neutrino masses from a light hidden sector

We study a class of models in which the particle that constitutes dark matter arises as a composite state of a strongly coupled hidden sector. The hidden sector interacts with the Standard Model through the neutrino portal, allowing the relic abundance of dark matter to be set by annihilation into final states containing neutrinos. The coupling to the hidden sector also leads to the generation of neutrino masses through the inverse seesaw mechanism, with composite hidden sector states playing the role of the singlet neutrinos. We focus on the scenario in which the hidden sector is conformal in the ultraviolet, and the compositeness scale lies at or below the weak scale. We construct a holographic realization of this framework based on the Randall-Sundrum setup and explore the implications for experiments. We determine the current constraints on this scenario from direct and indirect detection, lepton flavor violation and collider experiments and explore the reach of future searches. We show that in the near future, direct detection experiments and searches for μ → e conversion will be able to probe new parameter space. At colliders, dark matter can be produced in association with composite singlet neutrinos via Drell Yan processes or in weak decays of hadrons. We show that current searches at the Large Hadron Collider have only limited sensitivity to this new production channel and we comment on how the reconstruction of the singlet neutrinos can potentially expand the reach.

Semileptonic Ωb→Ωcℓν¯ℓ transition in full QCD

We investigate the semileptonic decay of Ωb→Ωcℓν¯ℓ in three lepton channels. To this end, we use the QCD sum rule method in three point framework to calculate the form factors defining the matrix elements of these transitions. Having calculated the form factors as building blocks, we calculate the decay widths and branching fractions of the exclusive decays in all lepton channels and compare the results with other theoretical predictions. The obtained results for branching ratios and ratio of branching fractions at different leptonic channels may help experimental groups in their search for these weak decays. Comparison of the obtained results with possible future experimental data can be useful to check the order of consistency between the standard model theory predictions and data on the heavy baryon decays. Published by the American Physical Society 2024

Stellar X-Ray Activity and Habitability Revealed by the ROSAT Sky Survey

Using the homogeneous X-ray catalog from ROSAT observations, we conducted a comprehensive investigation into stellar X-ray activity–rotation relations for both single and binary stars. Generally, the relation for single stars consists of two distinct regions: a weak decay region, indicating a continued dependence of the magnetic dynamo on stellar rotation rather than a saturation regime with constant activity, and a rapid decay region, where X-ray activity is strongly correlated with the Rossby number. Detailed analysis reveals more fine structures within the relation: in the extremely fast-rotating regime, a decrease in X-ray activity was observed with increasing rotation rate, referred to as supersaturation, while in the extremely slow-rotating region, the relation flattens, mainly due to the scattering of F stars. This scattering may result from intrinsic variability in stellar activities over one stellar cycle or the presence of different dynamo mechanisms. Binaries exhibit a similar relation to that of single stars while the limited sample size prevented the identification of fine structures in the relation for binaries. We calculated the mass-loss rates of planetary atmospheres triggered by X-ray emissions from host stars. Our findings indicate that for an Earthlike planet within the stellar habitable zone, it would easily lose its entire primordial H/He envelope (equating to about 1% of the planetary mass).

Analysis of hadronic weak decays of charmed baryons in the topological diagrammatic approach

We perform a global fit to the experimental data of two-body charmed baryon decays based on the topological diagrammatic approach (TDA) and take into account the phase shifts between S- and P-wave amplitudes as inspired by the recent BESIII measurement of the decay asymmetry in the decay Λc+→Ξ0K+. The TDA has the advantage that it is more intuitive, graphic, and easier to implement model calculations. The measured branching fractions and decay asymmetries are well accommodated in the TDA except for a few modes, in particular, the predicted B(Ξc0→Ξ−π+)=(2.83±0.10)% is larger than its current value. The equivalence of the TDA and the irreducible SU(3) approach (IRA) is established. We show that the number of the minimum set of tensor invariants in the IRA and the topological amplitudes in the TDA is the same and present their relations. The predicted magnitudes of S- and P-wave amplitudes and their phase shifts are presented for measured and yet-to-be-measured modes in both the TDA and IRA which can be tested in the near future. Besides the decay Λc+→Ξ0K+, there exist several modes which proceed only through W-exchange. In particular, the observed channel Ξc0→Σ+K− should have phase shifts similar to that in Λc+→Ξ0K+ and its decay asymmetry is predicted to be −0.21±0.17 which can be used to test our theoretical framework. In contrast, the TDA leads to a large α of order −0.93 for the decay Ξc+→Ξ0π+ even after the phase-shift effect is incorporated in the fit. Published by the American Physical Society 2024

Dynamics of heavy flavor in a weakly magnetized hot QCD medium

We obtain the spatial and momentum-diffusion coefficients (Ds and κ) and the collisional energy loss (dE/dx) of a heavy quark (HQ) traversing through a thermal medium of quarks and gluons in a weak magnetic field (B), for the two cases of the HQ moving either parallel or perpendicular to B. For that purpose, we consider Coulomb scatterings (t-channel) of the HQ with the light quarks, obtained from the imaginary part of the HQ self-energy via the cutting rules. Both the normalized (by T3) κ, and dE/dx, for charm quarks are larger than that for bottom quarks due to the larger mass of the latter. Also, the effect of B is more feeble on the bottom quark, compared to the charm quark. Comparatively, the magnitudes of both κ and dE/dx are significantly smaller for the case of v⊥B. For both the cases, our results show that the momentum transfer between the HQ and the medium takes place preferentially along the direction of HQ velocity, thus leading to a significant increase in the momentum-diffusion anisotropy, compared to B=0. We also calculate the (scaled) spatial diffusion coefficient, which we find to be independent of the heavy flavor mass and is almost unaffected by changes in B. Published by the American Physical Society 2024

Realtime dynamics of hyperon spin correlations from string fragmentation in a deformed four-flavor Schwinger model

Self-polarizing weak decays of Λ-hyperons provide unique insight into the role of entanglement in the fragmentation of QCD strings through measurements of the spin correlations of ΛΛ¯ pairs produced in collider experiments. The simplest quantum field theory representing the underlying parton dynamics is the four-flavor massive Schwinger model plus an effective spin-flip term, where the flavors are mapped to light (up or down) and heavy (strange) quarks and their spins. This construction provides a novel way to explore hyperon spin correlations in 1+1 dimensions. We investigate the evolution of these correlations for different string configurations that are sensitive to the rich structure of the model Hamiltonian. Published by the American Physical Society 2024

Signature decay modes of the compact doubly-heavy tetraquarks [formula omitted] and [formula omitted]

Based on the expectations that the lowest-lying doubly-bottom tetraquark Tbbu¯d¯ (JP=1+) and the bottom-charm tetraquark Tbcu¯d¯ (JP=0+) are stable against strong and electromagnetic decays, we work out a number of semileptonic and non-leptonic weak decays of these hadrons, making use of the heavy quark symmetry. In doing this, we concentrate on the exclusive decays involving also tetraquarks in the final states, i.e., transitions such as Tbbu¯d¯→Tbcu¯d¯(ℓ−νℓ,h−) and Tbcu¯d¯→Tccu¯d¯(ℓ−νℓ,h−), where h−=π−,ρ−,a1−,Ds−,Ds⁎−. So far, only the JP=1+ tetraquark Tccu¯d¯ has been discovered, which we identify with the I=0Tcc+ object, compatible with JP=1+ and having the pole mass relative to the D⁎+D0 mass threshold and decay widths δm=M(Tcc+)−(M(D⁎+)+M(D0))=−360±40−0+4 keV and Γ(Tcc+)=48−14+2 keV. Experimental discoveries of the transitions worked out here, and related ones involving doubly-heavy baryons, will quantify the diquark-antidiquark component of these tetraquarks.

K± → π±a at next-to-leading order in chiral perturbation theory and updated bounds on ALP couplings

The weak decays K± → π±a offer a powerful probe of axion-like particles (ALPs). In this work, we provide a comprehensive analysis of these processes within chiral perturbation theory, extending existing calculations by including complete next-to-leading order (NLO) contributions and isospin-breaking corrections at first order in (md – mu). We show that the consistent incorporation of ALPs in the QCD and weak chiral Lagrangians requires a non-trivial extension of the corresponding operator bases, which we describe in detail. Furthermore, we show that in the presence of an ALP the so-called “weak mass term”, which is unobservable in the Standard Model, is non-redundant already at leading order. We find that NLO corrections associated with flavor-violating ALP couplings modify the leading-order result by a few percent, with negligible uncertainties. NLO corrections proportional to flavor-conserving ALP couplings lead to potentially larger corrections, which, however, are accompanied by sizable uncertainties mainly due to the currently limited knowledge of various low-energy constants. We study how these corrections impact bounds on the ALP couplings, first model independently, and then specializing to the case of an ALP with flavor-universal couplings in the UV. Our findings confirm that the decays K± → π±a provide the strongest particle-physics constraints for ma ≲ 300 MeV. In addition, we point out that these bounds have interesting implications for the ALP couplings to nucleons, which were so far only constrained by astrophysical measurements and non-accelerator experiments.

Nonleptonic three-body charmed baryon weak decays with H(15)

We study the nonleptonic three-body charmed baryon weak decays of Bc→BnPP′ under the SU(3)F flavor symmetry, where Bc denotes the antitriplet charmed baryon, comprising (Ξc0,−Ξc+,Λc+), and Bn and P(P′) represent octet baryon and pseudoscalar meson states, respectively. In addition to 12 parameters from the contributions of the color-antisymmetric part of the effective Hamiltonian, denoted as H(6¯), there are 4 parameters from the color-symmetric one, H(15), which were not included in the previous study. With 16 parameters in total and 28 experimental data points, we obtain the minimal χ2 over degree of freedom of χ2/d.o.f=1.5, which is a great improvement comparing to that without H(15). With the better fitting values, we evaluate the branching ratios and up-down asymmetries of Bc→BnPP′, which present some interesting results such as B(Λc+→(Ξ(1690)0→Σ+K−)K+)≡(1.5±0.4)×10−3 and potential SU(3) breaking effects in Ξc+→pπ+K− and Λc+→Σ+π−K+ to be verified by the experiments at BESIII, Belle-II, and LHCb. Published by the American Physical Society 2024

Inhomogeneous long-range percolation in the weak decay regime

We study a general class of percolation models in Euclidean space including long-range percolation, scale-free percolation, the weight-dependent random connection model and several other previously investigated models. Our focus is on the weak decay regime, in which inter-cluster long-range connection probabilities fall off polynomially with small exponent, and for which we establish several structural properties. Chief among them are the continuity of the bond percolation function and the transience of infinite clusters.