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The spectra of Formula omitted and Formula omitted hexaquark states
Motivated by the recent observation of the [Formula omitted] resonance X(2085) in the [Formula omitted] system by the BESIII collaboration, we study the molecular states of [Formula omitted] and [Formula omitted] with baryon-antibaryon structures within the framework of the QCD sum rules. Non-perturbative contributions up to dimension 13 in quark operator expansion (OPE) are considered. Our calculation results indicate the possible existence of six [Formula omitted] and [Formula omitted] molecular states with quantum numbers [Formula omitted], which do not support X(2085), or at least not its main component, being a [Formula omitted] or [Formula omitted] molecular state. Additionally, the previously observed state X(2075) also lies in the vicinity of [Formula omitted] and [Formula omitted] molecular states, and its inner structure might not be entirely transparent, rather possibly a mixture of tetraquark and hexaquark states. The possible decay modes of the concerned states are analyzed.
Journal Article
Neutrino model in left-right symmetric linear seesaw augmented with Formula omitted modular group
In this work, we have invoked [Formula omitted] modular symmetry in the left-right symmetric linear seesaw model. Interestingly, such modular symmetry restricts the proliferation of flavon fields, and as a result, the predictability of the model is enhanced. The fermion sector of the model comprises quarks, leptons, and a sterile fermion in each generation, while the scalar sector consists of Higgs doublets and bidoublets. We investigate numerically various Yukawa coupling coefficients, the neutrino masses and mixing parameters in our intended model and predictions become consistent with the [Formula omitted] range of current neutrino oscillation data. We also studied the non-unitarity, effects on lepton flavor violation in our model and evolution of lepton asymmetry to explain the current baryon asymmetry of the universe.
Journal Article
Lattice artifacts of local fermion bilinears up to Formula omitted
Recently the asymptotic lattice spacing dependence of spectral quantities in lattice QCD has been computed to [Formula omitted] using Symanzik Effective theory (Husung et al. in Phys Lett B 829:137069, 2022; Husung in Eur Phys J C 83:142, 2023). Here, we extend these results to matrix elements and correlators of local fermion bilinears, namely the scalar, pseudo-scalar, vector, axial-vector, and tensor. This resembles the typical current insertions for the effective Hamiltonian of electro-weak or BSM contributions, but is only a small fraction of the local fields typically considered. We again restrict considerations to lattice QCD actions with Wilson or Ginsparg-Wilson quarks and thus lattice formulations of QCD without flavour-changing interactions realising at least [Formula omitted] flavour symmetries for [Formula omitted] sea-quarks and [Formula omitted] quenched valence-quarks respectively in the massless limit. Overall we find only few cases [Formula omitted], which worsen the asymptotic lattice spacing dependence [Formula omitted] compared to the classically expected [Formula omitted]-scaling. Other than for trivial flavour quantum numbers, only the axial-vector and much milder the tensor may cause some problems at [Formula omitted], strongly suggesting to use at least tree-level Symanzik improvement of those local fields.
Journal Article
Lattice calculation of the Formula omitted and Formula omitted s-wave scattering length
We calculate the s-wave scattering length in the [Formula omitted] sector of [Formula omitted] and the [Formula omitted] sector of [Formula omitted] using three [Formula omitted] twisted mass gauge ensembles with the pion mass [Formula omitted] MeV and lattice spacing [Formula omitted] fm, respectively. The scattering lengths are extracted using the conventional Lüscher finite size method. We observe sizable discretization effects and the results after a continuum extrapolation are [Formula omitted] fm and [Formula omitted] fm. The slight difference of light quark mass is ignored in this study. Our results indicate that the interaction between the two respective charmonia are repulsive in nature in both cases.
Journal Article
Constraints on the malaphoric Formula omitted model from di-lepton resonance searches at the LHC
We confront the malaphoric [Formula omitted] model with bounds coming from a search for resonances in the di-lepton channels at the 13 TeV LHC. In contrast to the original [Formula omitted] model, the [Formula omitted] of the malaphoric [Formula omitted] model has sizeable couplings to the lighter two families; these originate from order unity kinetic mixing with the hypercharge gauge boson and ameliorate the fit to lepton flavour universality measurements in B-meson decays. The [Formula omitted] coupling to the first two families of quark means that the resulting constraints from resonant di-lepton searches are stronger. Nevertheless, we find that for [Formula omitted] TeV there remains a non-negligible region of allowed parameter space where the model significantly improves upon several Standard Model predictions for observables involving the [Formula omitted] transition. We estimate that the 3000 fb [Formula omitted] HL-LHC will extend this sensitivity to [Formula omitted] TeV.
Journal Article
Four loop Green's functions involving the Formula omitted moment of the Wilson operator
We evaluate the Green's function for the insertion of the second moment of the twist-2 flavour nonsinglet Wilson operator in a quark 2-point function in all three different single scale external momentum configurations at four loops in the [Formula omitted] scheme and the chiral limit. One configuration is where the operator is inserted at zero momentum while the other two are where a non-zero momentum flows out through the operator itself with one external quark momentum nullified. In the latter two configurations mixing of the operator with a total derivative twist-2 operator is included for renormalization group consistency. In addition we compute the correlation functions of both gauge invariant operators to four loops in the same scheme.
Journal Article
Heavy Formula omitted mesons with open charm from Formula omitted interactions
In view of the recent discovery of [Formula omitted], which can be described as a [Formula omitted] molecular state, we perform a study of the [Formula omitted] system, and its extension to studying [Formula omitted], where [Formula omitted] is bound as a spin 1 [Formula omitted]-like state, to search for the possible existence of exotic mesons with the open flavors ccs being part of their quark configuration. Considering the additional attractive interactions present in the KD and [Formula omitted] subsystems, where the states [Formula omitted] and [Formula omitted] are generated, we solve the Faddeev equations considering the fixed-center approximation for the mentioned three-body systems and find the existence of two doubly charmed [Formula omitted]-like mesons, [Formula omitted] and [Formula omitted], with quantum numbers [Formula omitted]. Considering the respective three-body thresholds of the two systems, both [Formula omitted]-states are bound by around 60 MeV. An experimental confirmation will bring evidence for the existence of a degree of exoticity beyond charm +2.
Journal Article