Importance of confinement in instanton induced potential for bottomonium spectroscopy

Mass spectra of bottomonium states are computed using the Instanton Induced potential obtained from Instanton Liquid Model for QCD vacuum and incorporating a stronger confinement term. Spin dependent interactions through confined one gluon exchange potential are incorporated to remove the mass degeneracy. The mass spectra of the $$b\bar{b}$$ b b ¯ states up to 4S states are found to be in good agreement with the values reported by PDG(2020). Mixing of nearby isoparity states are also studied. We found the state $$\varUpsilon (10{,}860)$$ Υ ( 10 , 860 ) as an admixture of $$5^3S_1$$ 5 3 S 1 and $$6^3D_1$$ 6 3 D 1 Upsilon states with mixing angle $$\theta = 39.98^{\circ }$$ θ = 39 . 98 ∘ and the mixed state di-leptonic decay width is found to be 0.25 keV as against the width of $$0.31 \pm 0.07$$ 0.31 ± 0.07 keV reported by PDG. Further the state $$\varUpsilon (11{,}020)$$ Υ ( 11 , 020 ) is also found to be the admixture of $$6^3S_1$$ 6 3 S 1 and $$5^3D_1$$ 5 3 D 1 Upsilon states with the mixing angle $$\theta = 51.69^{\circ }$$ θ = 51 . 69 ∘ and the di-leptonic decay width of the mixed state is obtained as 0.14 keV which is very close to the width of $$0.13 \pm 0.03$$ 0.13 ± 0.03 keV reported by PDG. Present results indicates that addition of confinement to the instanton potential is crucial for the determination of the mass spectroscopy of heavy hadrons.

$$ \mathcal{N} $$ = 1 Super-Yang-Mills theory on the lattice with twisted mass fermions

Super-Yang-Mills theory (SYM) is a central building block for supersymmetric extensions of the Standard Model of particle physics. Whereas the weakly coupled subsector of the latter can be treated within a perturbative setting, the strongly coupled subsector must be dealt with a non-perturbative approach. Such an approach is provided by the lattice formulation. Unfortunately a lattice regularization breaks supersymmetry and consequently the mass degeneracy within a supermultiplet. In this article we investigate the properties of $$ \mathcal{N} $$ N = 1 supersymmetric SU(3) Yang-Mills theory with a lattice Wilson Dirac operator with an additional parity mass, similar as in twisted mass lattice QCD. We show that a special 45° twist effectively removes the mass splitting of the chiral partners. Thus, at finite lattice spacing both chiral and supersymmetry are enhanced resulting in an improved continuum extrapolation. Furthermore, we show that for the non-interacting theory at 45° twist discretization errors of order $$ \mathcal{O}(a) $$ O a are suppressed, suggesting that the same happens for the interacting theory as well. As an aside, we demonstrate that the DDαAMG multigrid algorithm accelerates the inversion of the Wilson Dirac operator considerably. On a 163× 32 lattice, speed-up factors of up to 20 are reached if commonly used algorithms are replaced by the DDαAMG.

Electroweak stability and discovery luminosities for new physics

What is the luminosity needed for discovering new physics if the electroweak scale is to remain stable? In this work we study this question, with the pertinent example of a real singlet scalar which couples to the Higgs field at the renormalizable level. Observing that the electroweak scale remains stable if the two scalars couple in a see-sawic fashion through a mass-degeneracy-driven unification linkup among quartic couplings at a given scale, we show by detailed simulation studies of the $$pp\rightarrow (\mathrm{singlet\ scalar}) \rightarrow Z Z \rightarrow 4\ell $$ p p → ( singlet scalar ) → Z Z → 4 ℓ channel that the HL-LHC, which is expected to deliver an integrated luminosity of $$3~\mathrm{ab^{-1}}$$ 3 ab - 1 , has no significant excess of signal over the background in the 800–2000 GeV mass range. The FCC-hh, on the other hand, can discover scalars up to a mass of 870 GeV with an integrated luminosity $$20~\mathrm{ab^{-1}}$$ 20 ab - 1 . Observation at $$3\sigma $$ 3 σ (discovery at $$5\sigma $$ 5 σ ) of a new scalar with a minimum mass 800 GeV requires at least $$2~\mathrm{ab^{-1}}$$ 2 ab - 1 ($$5.2~\mathrm{ab^{-1}}$$ 5.2 ab - 1 ) integrated luminosity, showing that the new physics that does not destabilize the electroweak scale is accessible only at very high luminosities, and can be tested already in the early stages of the FCC-hh operation period.

Lorentz invariant CPT breaking in the Dirac equation

If one modifies the Dirac equation in momentum space to [Formula: see text], the symmetry of positive and negative energy eigenvalues is lifted by [Formula: see text] for a small [Formula: see text]. The mass degeneracy of the particle and antiparticle is thus lifted in a Lorentz invariant manner since the combinations [Formula: see text] with step functions are manifestly Lorentz invariant. We explain an explicit construction of this CPT breaking term in coordinate space, which is Lorentz invariant but nonlocal at the distance scale of the Planck length. The application of this Lorentz invariant CPT breaking mechanism to the possible mass splitting of the neutrino and antineutrino in the Standard Model is briefly discussed.

Paraquantum strings in noncommutative space–time

A parabosonic string is assumed to propagate in a total noncommutative target phase space. Three models are investigated: open strings, open strings between two parallel [Formula: see text] branes and closed ones. This leads to a generalization of the oscillators algebra of the string and the corresponding Virasoro algebra. The mass operator is no more diagonal in the ordinary Fock space, a redefinition of this later will modify the mass spectrum, so that, neither massless vector state nor massless tensor state are present. The restoration of the photon and the graviton imposes specific forms of the noncommutativity parameter matrices, partially removes the mass degeneracy and gives new additional ones. In particular, for the [Formula: see text]-branes, one can have a tachyon free model with a photon state when more strict conditions on these parameters are imposed, while, the match level condition of the closed string model induces the reduction of the spectrum.

DSMesons in Asymmetric Hot and Dense Hadronic Matter

The in-medium properties ofDSmesons are investigated within the framework of an effective hadronic model, which is a generalization of a chiralSU(3)model, toSU(4), in order to study the interactions of the charmed hadrons. In the present work, theDSmesons are observed to experience net attractive interactions in a dense hadronic medium, hence reducing the masses of theDS+andDS-mesons from the vacuum values. While this conclusion holds in both nuclear and hyperonic media, the magnitude of the mass drop is observed to intensify with the inclusion of strangeness in the medium. Additionally, in hyperonic medium, the mass degeneracy of theDSmesons is observed to be broken, due to opposite signs of the Weinberg-Tomozawa interaction term in the Lagrangian density. Along with the magnitude of the mass drops, the mass splitting betweenDS+andDS-mesons is also observed to grow with an increase in baryonic density and strangeness content of the medium. However, all medium effects analyzed are found to be weakly dependent on isospin asymmetry and temperature. We discuss the possible implications emanating from this analysis, which are all expected to make a significant difference to observables in heavy ion collision experiments, especially the upcoming Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR), GSI, where matter at high baryonic densities is planned to be produced.

Bottom-strange mesons in hyperonic matter

The in-medium behavior of bottom-strange pseudoscalar mesons in hot, isospin asymmetric and dense hadronic environment is studied using a chiral effective model. The same was recently generalized to the heavy quark sector and employed to study the behavior of open-charm and open-bottom mesons. The heavy quark (anti-quark) is treated as frozen and all medium modifications of these bottom-strange mesons are due to their strange anti-quark (quark) content. We observe a pronounced dependence of their medium mass on baryonic density and strangeness content of the medium. Certain aspects of these in-medium interactions are similar to those observed for the strange-charmed mesons in a preceding investigation, such as the lifting of mass-degeneracy of [Formula: see text] and [Formula: see text] mesons in hyperonic matter, while the same is respected in vacuum as well as in nuclear matter. In general, however, there is a remarkable distinction between the two species, even though the formalism predicts a completely analogous in-medium interaction Lagrangian density. We discuss in detail the reason for different in-medium behavior of these bottom-strange mesons as compared to charmed-strange mesons, despite the dynamics of the heavy quark being treated as frozen in both cases.