Search

In this work, we investigate the complete spectroscopy of the B c mesons, with a special focus on the consideration of the unquenched effects. To account for such effects, we employ the modified Godfrey–Isgur model and introduce a screening potential. The resulting mass spectrum of the concerned higher B c states is then presented, showing significant deviations after considering the unquenched effects. This emphasizes the importance of considering the unquenched effects when studying of the higher B c mesons. Furthermore, we determine the corresponding spatial wave functions of these B c mesons, which have practical applications in subsequent studies of their decays. These decays include two-body Okuba–Zweig–Iizuka allowed strong decays, dipion transitions between B c mesons, radiative decays, and some typical weak decays. With the ongoing high-luminosity upgrade of the Large Hadron Collider, we expect the discovery of additional B c states in the near future. The knowledge gained from the mass spectrum and the different decay modes will undoubtedly provide valuable insights for future experimental explorations of these higher B c mesons. [ABSTRACT FROM AUTHOR]

We study the masses and production modes of pentaquark with the quark constituent c q ¯ q q q , by the tridiquark-diquark model and systematical light flavor quark symmetry SU(3) analysis. The mass spectrums show that the S-wave singly charm pentaquark c n ¯ n n n , c s ¯ s s n , c n ¯ s s n and c n ¯ s n n (n = u , d) are above their strong decay thresholds, while c s ¯ n n n and c s ¯ s n n with parity 1 2 - are below their strong decay thresholds, which imply the possibility of stable states. Furthermore, we discuss the production of the concerned 15 states from B meson, the analysis within SU(3) symmetry yields the golden channels of production process, B ¯ s 0 → F s ¯ u d d + p ¯ , B - → F u ¯ d d s - Λ ¯ 0 , which expected to be work worthily in b-factory. [ABSTRACT FROM AUTHOR]

We explore the first radial excitation X 4c ∗ of the fully charmed diquark-antidiquark state X 4c = c c c ¯ c ¯ built of axial-vector components, and the hadronic molecule M = χ c 1 χ c 1 . The masses and current couplings of these scalar states are calculated in the context of the QCD two-point sum rule approach. The full widths of X 4c ∗ and M are evaluated by taking into account their kinematically allowed decay channels. We find partial widths of these processes using the strong couplings g i ∗ and G i (∗) at the X 4c ∗ (M )-conventional mesons vertices computed by means of the QCD three-point sum rule method. The predictions obtained for the parameters m = (7235 ± 75) MeV , Γ = (144 ± 18) MeV and m ~ = (7180 ± 120) MeV , Γ ~ = (169 ± 21) MeV of these structures, are compared with the experimental data of the CMS and ATLAS Collaborations. In accordance to these results, within existing errors of measurements and uncertainties of the theoretical calculations, both the excited tetraquark and hadronic molecule may be considered as candidates to the resonance X(7300). Detailed analysis, however, demonstrates that the preferable model for X(7300) is an admixture of the molecule M and sizeable part of X 4c ∗ . [ABSTRACT FROM AUTHOR]

A formalism for the experimental analysis of mesons produced by a beam of linearly polarized photons is presented. This formalism introduces a more general use of the reflectivity operator. The goal is to recognize resonances in cross-sections, their associated quantum numbers, and production mechanisms by performing partial wave analysis of multiple-meson final states. [ABSTRACT FROM AUTHOR]

The flavor-changing neutral current (FCNC) decays of charmed hadrons with missing energy (Ɇ) can serve as potentially promising hunting grounds for hints of new physics, as the standard-model backgrounds are very suppressed. A few of such processes have been searched for in recent experiments, specifically D0→ Ɇ by Belle and D0→ π0Ɇ and Λ c + → pɆ by BESIII, resulting in upper bounds on their branching fractions. We consider them to illuminate the possible contributions of the quark transition c → uɆ with a couple of invisible spinless bosons carrying away the missing energy, assuming that they are not charge conjugates of each other and hence can have unequal masses. We find that these data are complementary in that they constrain different sets of the underlying operators and do not cover the same ranges of the bosons' masses, but there are regions not yet accessible. From the allowed parameter space, we show that other D-meson decays, such as D → ρɆ, and the charmed-baryon ones Ξc → (Σ, Λ)Ɇ can have sizable branching fractions and therefore may offer further probes of the new-physics interactions. We point out the importance of D0 → γɆ which are not yet searched for but could access parts of the parameter space beyond the reach of the other modes. In addition, we look at a scenario where the invisibles are instead fermionic, namely sterile neutrinos, and a scalar leptoquark mediates c → uɆ. We discuss the implications of the aforesaid bounds for this model. The predictions we make for the various charmed-hadron decays in the different scenarios may be testable in the near future by BESIII and Belle II. [ABSTRACT FROM AUTHOR]

We consider SU(2) quantum chromodynamics in 1 + 1 dimensions with a single quark in the spin J representation of the gauge group and study the theory in the large J limit where the gauge coupling g2 → 0 and J → ∞ with λ = g2J2 fixed. We work with a Dirac spinor field for arbitrary J, and with a Majorana spinor for integer J since the integer spin representations of SU(2) are real, and analyze the two cases separately. The theory is reformulated in terms of global colour non-singlet fermion bilocal operators which satisfy a W∞ × U(2J + 1) algebra. In the large J limit, the dynamics of the bilocal fields is captured by fluctuations along a particular coadjoint orbit of the W∞ algebra. We show that the global colour-singlet sector of the bilocal field fluctuations satisfy the same integral equation for meson wavefunctions that appears in the 't Hooft model. For Majorana spinors in the integer spin J representation, the Majorana condition projects out half of the meson spectrum, as a result of which the linear spacing of the asymptotic meson spectrum for Majorana fermions is double that of Dirac fermions. The Majorana condition also projects out the zero mass bound state that is present for the Dirac quark at zero quark mass. We also consider the formulation of the model in terms of local charge densities and compute the quark spectral function in the large J limit: we see evidence for the absence of a pole in the quark propagator. [ABSTRACT FROM AUTHOR]

We study the meson spectrum of the N = 4 supersymmetric Yang-Mills theory with N = 2 fundamental hypermultiplets for a finite electric field by using the D3/D7 model. The spectrum for scalar and vector mesons is computed by analyzing the (quasi-)normal modes for the fluctuations of the D7-brane embedding and gauge fields. In the presence of an electric field, two different phases in the background are realized: the meson and dissociation phases. In this paper, we analyze the meson spectrum of scalar and vector mesons for all ranges of the electric field and explore the effect of the electric field on the meson spectrum, that is, the Stark effect. In the meson spectrum, we observe the avoided crossing between different levels due to the coupling of fluctuations via the electric field. [ABSTRACT FROM AUTHOR]

We calculate the next-to-leading order QCD corrections to B to scalar meson form factors from QCD light-cone sum rules with B meson light-cone distribution amplitudes. We demonstrate that the B meson-to-vacuum correlation functions can be factorized into the convolution of short-distance coefficients and light-cone distribution amplitudes at the one-loop level and find that only ϕ B + (ω, μ) contributes to the form factors. We then employ the z-parameterization combined with constraints from strong coupling constants to reconstruct the q2 dependence of the form factors in the whole kinematic allowed regions. Due to the large cancellations between the hard functions and the jet functions, the next-to-leading order results show a modest increase of approximately 5% compared to the leading order results. Based on the results of form factors, we predict the branching ratios of semi-leptonic B → S ℓ ν ¯ ℓ and B → S ν ℓ ν ¯ ℓ processes, as well as several angular observables, such as forward-backward asymmetries, "flat terms" and lepton polarization asymmetries. We compare these results with calculations from other methods. Experimental verification of these results is required in future experiments. [ABSTRACT FROM AUTHOR]

Exclusive semileptonic b hadron decays (b → uℓν) serve as a sandbox for probing strong and electroweak interactions and for extracting the CKM element Vub. Instead, this work investigates their underexplored potential to reveal new short-distance physics. Utilizing SMEFT as a conduit to chart territory beyond the SM, we demonstrate that substantive new physics contributions in b → uℓν are necessarily linked to correlated effects in rare neutral-current b decays, neutral B meson mixing or high-mass Drell-Yan tails. We find that measurements of the latter processes strongly restrict the allowed deviations in the former. A complete set of tree-level mediators, originating from a perturbative ultraviolet model and matching at dimension 6, is thoroughly explored to support this assertion. As a showcase application, we examine the feasibility of a new physics interpretation of the recent tension in exclusive |Vub| extraction from B → Vℓν where V = (ρ, ω). [ABSTRACT FROM AUTHOR]

The availability of simultaneous X-ray and very high energy (VHE) observations of blazars helps to identify the plausible radiative contributors to the VHE emission. Under leptonic scenario, the VHE emission from BL Lacs are attributed to the synchrotron self Compton (SSC) emission. However, many BL Lacerate (BL Lacs) have shown significant hardening at VHE after correction for the extragalactic background light (EBL) attenuation. We study the spectral hardening of two nearby BL Lac objects, Mkn 421 and Mkn 501 having most number of simultaneous X-ray and VHE observations available among all the blazars. These BL Lacs are relatively close and the effect of EBL attenuation is relatively minimal/negligible. We study the scatter plot between the X-ray spectral indices and intrinsic VHE indices to identify the plausible origin of the VHE emission. For Mkn 501, the VHE spectral indices are steeper than X-ray spectra, suggesting the scattering process happening at extreme Klein–Nishina regime. On the other hand, for Mkn 421, the VHE spectra is remarkably harder than the X-ray spectra, which suggests an additional emission mechanism other than the SSC process. We show this hard VHE spectrum of Mkn 421 can be explained by considering the inverse Compton (IC) emission from a broken power-law electron distribution with Maxwellian pileup. The possibility of the hadronic contribution at VHE γ-rays is also explored by modelling the hard spectrum under the photomeson process. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the mass spectra and decay properties of B , B s and B c mesons using the relativistic potential model with confining potential V q (r) = 1 2 (1 + γ 0) (a 2 r + V 0). The calculated mass spectra of B , B s and B c accord to the findings of the experiments and other theoretical forecasts. Using the same parameters, we calculate possible radiative decay widths of V (n s) → P (n s) γ and P (n s) → V (n s) γ , n = 1 , 2 , 3 and weak leptonic decay constants of B , B s and B c mesons. Our results, in most cases, generally agree with experimental and other theoretical predictions. Finally, we also investigate mixing parameters x q , y q and χ q for B q 0 − B ¯ q 0 (q ϵ d , s) mesons, where our calculated values reasonably agree with the experiment. [ABSTRACT FROM AUTHOR]

In recent times, there have been several observations suggesting deviations from lepton universality in semileptonic decays of B mesons. These deviations have been noticed both in the neutral-current transitions (b → s l l) and charged-current transitions (b → c l ν ̄ l ). Motivated by these intriguing findings, we investigate the semileptonic decays involving the quark-level transitions of b → c l ν ̄ l . To explore the presence of new physics, we adopt a model-independent approach and analyze the processes Λ b → Λ c τ ν ̄ τ , B c + → η c τ + ν τ and B → D ∗ ∗ τ ν ̄ τ , where D ∗ ∗ = D 0 ∗ , D 1 ∗ , D 1 , D 2 ∗ represent the four lightest excited charm mesons. Considering a comprehensive effective Hamiltonian, we perform a global fit using various sets of new coefficients and incorporate measurements of R D , R D ∗ , R J ∕ ψ , P τ D ∗ , as well as the upper limit on the branching ratio of B c + → τ + ν τ . Subsequently, we examine the impact of constrained new couplings on the branching ratios, forward–backward asymmetry parameters, lepton nonuniversality (LNU) ratios, as well as lepton and hadron polarization asymmetries in these decay modes. [ABSTRACT FROM AUTHOR]

Relativistic corrections to the pair production of mesons and baryons consisting of heavy quarks and in the Higgs boson decay are calculated. Relativistic amplitudes and decay rates are constructed within perturbative Standart Model and relativistic quark model. The numerical values of the relativistic effects turn out to be significant and must be taken into account in order to achieve good calculation accuracy. [ABSTRACT FROM AUTHOR]

In heavy-ion reactions, statistical models predict a rapid change in the baryon-to-meson ratio as a function of the collision energy. This change occurs when the hadronic medium transits from a baryon- to a meson-dominated gas. The transition is expected to take place at a temperature around 140 MeV and a baryon chemical potential around 420 MeV, corresponding to a center-of-mass collision energy of GeV. The energy range of the MPD experiment will be suitable for the exploration of this transition region. We present preliminary results of feasibility studies for the measurement of the transverse momentum spectra for mesons and baryons, using Monte Carlo data samples, in order to study the crossing point between these transverse momenta, as a function of the centrality and collision energy. [ABSTRACT FROM AUTHOR]

At present, production, properties, and decays of heavy baryons are vigorously studied both experimentally and theoretically. The flavor symmetry allows an existence of a large number of hidden charm pentaquark states which differ by their light quark content. Here, ratios of weak decay widths of bottom baryons into a pentaquark and light meson are presented. The most interesting for experimental observation decays of bottom baryons are specified. [ABSTRACT FROM AUTHOR]

New NICA accelerator complex at JINR (Dubna), based on the existing upgraded Nuclotron accelerator, will allow conducting all types of research in the field of high-energy physics. The main tasks of this project are study of the properties of the deconfinement phase transition, experimental investigation on medium modification of vector mesons, and search for the QCD critical end point. Thus, two interaction points are foreseen in the NICA collider: one for studying the collision of heavy ions on the Multipurpose detector MPD, the other for polarized beams for the experiment on the SPD installation. The ambitious physical goals of MPD require excellent particle identification at the maximum possible range of phase space. Identification of charged hadrons is achieved by combining time-of-flight measurements and energy loss measurements from the time-projection camera TPC. The Time-of-Flight system is based on multigap resistive plate chambers (MRPC), which are successfully used to identify particles in similar experiments around the world. A production site has been organized at the Laboratory of High Energy Physics of JINR for serial production of TOF MPD modules including 10 MRPCs. This site includes the entire cycle of work from preparing materials for the assembly of detectors to testing the assembled modules on cosmic radiation. This report presents the structure of the TOF system, its main parameters, the current state and the results of decoding and processing data obtained at the module testing facility. [ABSTRACT FROM AUTHOR]

The deconfined state of strongly interacting quarks and gluons, quark–gluon plasma, may be formed in relativistic ion collisions at sufficient temperature and energy density. The signatures of quark–gluon plasma formation were observed in heavy-ion collisions by studying meson production. In small-collision systems, such as , , , and , the volume and lifetime of the produced medium might be insufficient for observation of quark–gluon plasma effects. However various physics mechanisms reflecting initial state of the collision, cold nuclear matter effects, may lead to a collective-like behavior in small-collision systems without quark–gluon plasma formation. The nuclear modified parton distribution functions are considered to be an underlying physics mechanism of cold nuclear matter effects. This paper presents the comparison of meson production in , , , and collisions at GeV at midrapidity ( , measured by PHENIX, to PYTHIA calculations with nuclear modified parton distribution functions EPPS16 and CTEQ15. The meson production in collisions at GeV might be driven by mechanisms additional to nuclear modification of parton distribution functions. [ABSTRACT FROM AUTHOR]

The invariant differential cross sections of inclusive and mesons were measured at midrapidity in pp collisions at TeV and in p–Pb collisions at TeV in a wide transverse momentum () range with the ALICE experiment. The unprecedented large range up to 200 GeV/ for mesons was achieved by combining various analysis techniques as well as triggers involving the Electromagnetic Calorimeter (EMCal) and the Photon Spectrometer (PHOS). A method to reconstruct properly merged clusters of high neutral pions, originally developed for EMCal, was implemented in PHOS and its results are discussed for the first time in this paper. The obtained cross sections provide strong constraints on parton distributions and fragmentation functions for light mesons, and can be used to further improve the theoretical descriptions of hadron production. The first multiplicity study of light-neutral meson production in pp collisions at TeV shows modification of light-neutral meson yields. The nuclear modification factors, recently measured in p–Pb collisions at TeV for high , are consistent with unity, providing no evidences of parton energy loss in small colliding systems. [ABSTRACT FROM AUTHOR]

The radiative B to tensor K 2 * (1430) , f 2 (1270) , a 2 (1320) meson decays are studied at next-to-leading order in soft-collinear effective theory (SCET). The SCET allows the systematic treatment of factorizable and non-factorizable contributions along with the resummation of large perturbative logarithms. We performed a two-step matching and determined the soft-overlap function ζ T ⊥ and branching ratios for these B to tensor meson decays. In the case of B → K 2 * (1430) γ , the numerical value of the branching ratio lies close to its experimental measurements. The estimated values of the branching ratios of Cabibbo–Kobayashi–Maskawa suppressed decays B → a 2 (1320) , f 2 (1270) γ are significantly small compared to that of B → K 2 * (1430) γ , but still could be measured in some ongoing and future B physics experiments. [ABSTRACT FROM AUTHOR]

When water vapor reacts with metals at temperatures of a few hundred kelvin, free hydrogen and metal oxides are formed. Iron is a common metal giving such reactions. Iron oxide together with a small amount of alkali metal as promoter is a good catalyst for forming ultradense hydrogen H(0) from the released hydrogen. Ultradense hydrogen is the densest form of condensed matter hydrogen. It can be formed easily at low pressure and is the densest material in the Solar System. Spontaneous and induced nuclear processes in H(0) create mesons (kaons, pions) in proton annihilation reactions. It is here agreed on that the great difference in the present conditions on Venus and Earth are caused by the initial difference in the temperatures of the planets due to their different distances from the Sun. This temperature difference means that, in warmer planetary environments such as on Venus, the iron + water steam → iron oxide + hydrogen reaction proceeded easily, meaning a consumption of water to give H(0) formation and release of nuclear energy by subsequent nuclear reactions in H(0). On the slightly cooler Earth, the iron + liquid water reaction was slower, and less water formed H(0). Thus, the water consumption and the heating due to nuclear reactions was smaller on Earth. The experiments proving that the mechanisms of forming H(0) and the details of the nuclear processes have been published. The more intense particle radiation from the nuclear processes in H(0) and the lack of water probably impeded formation of complex molecules and, thus, of life on planets like Venus. These processes in H(0) may, therefore, also imply a narrower zone of life in a planetary system than believed previously. [ABSTRACT FROM AUTHOR]

Lepton flavor universality exists in the Standard Model, and hence any observation of the violation of this universality will be a hint for new physics. Recent experimental searches for processes violating this symmetry have attracted much attention among theorists and experimentalists alike. In recent years, such hints have been observed in flavor changing neutral current weak processes such as b → s l l and charged current weak processes such as b → c l ν processes by collider experiments like Belle, Belle II, BaBar, LHCb, ATLAS, and CMS collaborations, where b , s , c are the bottom, strange, and charm quarks, respectively, and l , ν stand for lepton and the corresponding lepton neutrino, respectively. This article is a review of some of the interesting anomalies observed in the B-sector and includes decays of B s mesons. [ABSTRACT FROM AUTHOR]

In this paper, we present two machine learning algorithms to identify D mesons produced in a colour singlet state from radiative W boson decays at the LHC. The combined network algorithm is able to identify D mesons via its hadronic decays with an efficiency of 47% while suppressing a background of quark and gluon jets by a factor of 100. Using the developed algorithm, we perform a prospective study for the measurement of B (W → D s γ) . [ABSTRACT FROM AUTHOR]

The forward η mesons production has been observed by the Large Hadron Collider forward (LHCf) experiment in proton-proton collision at s = 13 TeV. This paper presents the measurement of the inclusive production rate of η in pT< 1.1 GeV/c, expressed as a function of the Feynman-x variable. These results are compared with the predictions of several hadronic interaction models commonly used for the modelling of the air showers produced by ultra-high energy cosmic rays. This is both the first measurement of η mesons from LHCf and the first time a particle containing strange quarks has been observed in the forward region for high-energy collisions. These results will provide a powerful constraint on hadronic interaction models for the purpose of improving the understanding of the processes underlying the air showers produced in the Earth's atmosphere by ultra-energetic cosmic rays. [ABSTRACT FROM AUTHOR]

The second-order (v2) and third-order (v3) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J/ψ, as well as prompt ψ(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of s NN = 5.02 TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb−1 recorded with the CMS detector. The J/ψ and ψ(2S) mesons are reconstructed using their dimuon decay channel. The v2 and v3 coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measured v2 values for prompt J/ψ mesons are found to be larger than those for nonprompt J/ψ mesons. The prompt J/ψ v2 values at high pT are found to be underpredicted by a model incorporating only parton energy loss effects in a quark-gluon plasma medium. Prompt and nonprompt J/ψ meson v3 and prompt ψ(2S) v2 and v3 values are also reported for the first time, providing new information about heavy quark interactions in the hot and dense medium created in heavy ion collisions. [ABSTRACT FROM AUTHOR]

The cross section for coherent photonuclear production of J/ψ is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of s NN = 5.02 TeV. Cross sections are presented in five different J/ψ rapidity ranges within |y| < 4, with the J/ψ reconstructed via its dilepton decay channels. In some events the J/ψ is not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range 17 < Wγ Pb,n < 920 GeV, where Wγ Pb,n is the centre-of-mass energy per nucleon of the γPb system. This range corresponds to a Bjorken-x interval spanning about three orders of magnitude: 1.1 × 10−5 < x < 3.3 × 10−2. In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies. [ABSTRACT FROM AUTHOR]

This paper reports the observation of the decays B s 0 → Ds1(2536)∓K± using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The branching fractions of these decays are measured relative to the normalisation channel B0→ D ¯ 0K+K−. The Ds1(2536)− meson is reconstructed in the D ¯ *(2007)0K− decay channel and the products of branching fractions are measured to be B B s 0 → D s 1 2536 ∓ K ± × B D s 1 2536 − → D ¯ ∗ 2007 0 K − = 2.49 ± 0.11 ± 0.12 ± 0.25 ± 0.06 × 10 − 5 , B B 0 → D s 1 2536 ∓ K ± × B D s 1 2536 − → D ¯ ∗ 2007 0 K − = 0.510 ± 0.021 ± 0.036 ± 0.050 × 10 − 5. The first uncertainty is statistical, the second systematic, and the third arises from the uncertainty of the branching fraction of the B0→ D ¯ 0K+K− normalisation channel. The last uncertainty in the B s 0 result is due to the limited knowledge of the fragmentation fraction ratio, fs/fd. The significance for the B s 0 and B0 signals is larger than 10 σ. The ratio of the helicity amplitudes which governs the angular distribution of the Ds1(2536)−→ D ¯ *(2007)0K− decay is determined from the data. The ratio of the S- and D-wave amplitudes is found to be 1.11 ± 0.15 ± 0.06 and the phase difference between them 0.70 ± 0.09 ± 0.04 rad, where the first uncertainty is statistical and the second systematic. [ABSTRACT FROM AUTHOR]

We attempt to apply the Regge trajectory approach to the heavy-light diquarks composed of one heavy quark and one light quark. However, we find that the direct application of the usual Regge trajectory formula for the heavy-light mesons and baryons fails. In order to correctly estimate the masses of the heavy-light diquarks, it is needed to consider the light quark mass correction and the parameter C in the Cornell potential within the Regge trajectory formula. By using the modified Regge trajectory formulas, we are able to estimate the masses of the heavy-light diquarks (cu), (cs), (bu) and (bs), which agree with other theoretical results. It is illustrated that the heavy-light diquarks satisfy the universal descriptions irrespective of heavy quark flavors, similar to other heavy-light systems such as the heavy-light mesons, the heavy-light baryons composed of one heavy quark (diquark) and one light diquark (quark), and the heavy-light tetraquarks composed of one heavy diquark (antidiquark) and one light antidiquark (diquark). The diquark Regge trajectory provides a new and very simple approach for estimating the spectra of the heavy-light diquarks. [ABSTRACT FROM AUTHOR]

A study of double charmed meson production in proton–proton and proton–nucleus collisions at the LHC energies is performed. Based on the color dipole formalism developed in the transverse momentum representation and the double parton scattering mechanism, predictions are made for the transverse momentum differential cross section for different pairs of D-mesons. The theoretical results consider the center-of-mass energy and forward rapidities associated to the measurements by the LHCb Collaboration. The results considering different unintegrated gluon distributions are presented and compared to data and predictions for proton–nucleus collisions are provided. [ABSTRACT FROM AUTHOR]

We calculated transitions of the higher radial excited charmonia ψ (n S) (n = 3 , 4 , 5) to the orbital excited charmonium h c (1 P) with emission of one pion or eta meson. In calculations, the intermediate S- and P-wave charmed meson loops were considered in terms of the nonrelativistic effective field theory. The results indicate that the transitions of interest are dominated by the loops involving the s l P = (1 / 2) + charmed mesons, whereas the s l P = (1 / 2) - charmed meson loops are of minor contributions. The partial decay widths of ψ (n S) → h c π 0 are of the order of 0.01–1 keV. For the case of ψ (n S) → h c η , the partial decay widths are from 0.1 to 100 keV, implying the branching ratios from 10 - 5 to 10 - 3 . Moreover, the partial decay widths for ψ (n S) → h c η are found to decrease as the η - η ′ mixing angle increases. It is hoped that the present calculated results would be observed in the future experiments. [ABSTRACT FROM AUTHOR]

It was demonstrated in a series of papers employing unitarized chiral perturbation theory that the phenomenology of the scalar open-charm state, the D 0 ∗ (2300) , can be understood as the interplay of two poles, corresponding to two scalar-isospin doublet states with different SU(3) flavor content. Within this formalism the lightest open charm positive parity states emerge as being dynamically generated from the scattering of the Goldstone-boson octet off D mesons, a picture that at the same time solves various problems that the experimental observations posed. However, in recent lattice studies of D π scattering at different pion masses only one pole was reported in the D 0 ∗ channel, while it was not possible to extract reliable parameters of a second pole from the lattice data. In this paper we demonstrate how this seeming contradiction can be understood and that imposing SU(3) constraints on the fitting amplitudes allows one to extract information on the second pole from the lattice data with minimal bias. The results may also be regarded as a showcase how approximate symmetries can be imposed in the K-matrix formalism to reduce the number of parameters. [ABSTRACT FROM AUTHOR]

Atmospheric muon neutrinos are produced by meson decays in cosmic-ray-induced air showers. The flux depends on meteorological quantities such as the air temperature, which affects the density of air. Competition between decay and re-interaction of those mesons in the first particle production generations gives rise to a higher neutrino flux when the air density in the stratosphere is lower, corresponding to a higher temperature. A measurement of a temperature dependence of the atmospheric ν μ flux provides a novel method for constraining hadronic interaction models of air showers. It is particularly sensitive to the production of kaons. Studying this temperature dependence for the first time requires a large sample of high-energy neutrinos as well as a detailed understanding of atmospheric properties. We report the significant ( > 10 σ ) observation of a correlation between the rate of more than 260,000 neutrinos, detected by IceCube between 2012 and 2018, and atmospheric temperatures of the stratosphere, measured by the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA's AQUA satellite. For the observed 10 % seasonal change of effective atmospheric temperature we measure a 3.5(3) % change in the muon neutrino flux. This observed correlation deviates by about 2-3 standard deviations from the expected correlation of 4.3 % as obtained from theoretical predictions under the assumption of various hadronic interaction models. [ABSTRACT FROM AUTHOR]

The quark-antiquark components of the U(3) lightest scalar meson nonet are investigated by considering the Nambu-Jona-Lasinio model with flavor-dependent coupling constants that were derived by considering (non-perturbative) gluon exchange. The strange quark effective mass ( M s * ) is varied such that the strangeness content of these scalar mesons can be analyzed further. The neutral states S 0, S 8, and S 3 are adopted as the most relevant quark-antiquark components, respectively, of the σ (500), f 0(980) and A 0 0 (980) mesons. As a result, the mass hierarchy between states S 0 and S 8, and K 0 * (700) − A 0 (980) mesons, can be, respectively, inverted and corrected for quite low values of the strange quark constituent mass. In addition, for some particular values of M s * , the masses of σ (500) and f 0(980) can also be obtained by considering the mixing coupling constant G 08. However, the masses of all the nine mesons are not described simultaneously in a self-consistent procedure and this goes along with the need of non-quark-antiquark states to completely describe their masses. A neutral-meson mixing matrix is defined and the leading mixing angle is found by fitting a correct value of the σ (500) − f 0(980) mass difference. Two different estimates for the strengths of the mixings A 0 0 → f 0 and f 0 → A 0 0 are proposed, leading to somewhat different behaviors. First by assuming leading transitions to intermediary flavor eigenstates and second by considering a dynamical evolution. The results may be in good agreement with experimental values from BESS-III depending on the value of the strange quark effective mass. [ABSTRACT FROM AUTHOR]

Heavy and light quarks produced in high- p T partonic collisions radiate differently. Heavy quarks regenerate their color field, stripped-off in the hard reaction, much faster than the light ones and radiate a significantly smaller fraction of the initial quark energy. This peculiar feature of heavy-quark jets leads to a specific shape of the fragmentation functions observed in e + e − annihilation. Differently from light flavors, the heavy quark fragmentation function strongly peaks at large fractional momentum z, i.e., the produced heavy–light mesons, B or D, carry the main fraction of the jet momentum. This is a clear evidence of the dead-cone effect, and of a short production time of a heavy–light mesons. Contrary to propagation of a small q q ¯ dipole, which survives in the medium due to color transparency, a heavy–light Q q ¯ dipole promptly expands to a large size. Such a big dipole has no chance to remain intact in a dense medium produced in relativistic heavy ion collisions. On the other hand, a breakup of such a dipole does not affect much the production rate of Q q ¯ mesons, differently from the case of light q q ¯ meson production. [ABSTRACT FROM AUTHOR]

This paper was written in memory of Joao da Providência who passed away in November 2021. It is a pursuit of works developed recently by Joao, Steven and inspired by our many years of discussions. Neutron stars are described within the quark–meson coupling Bogoliubov (QMC Bogoliubov) nuclear model which includes u, d and s quarks. The model is improved by including the ω - b 3 mixing term so that constraints imposed by ab-initio chiral effective field theory pure neutron matter calculations are satisfied. The effects of the symmetry energy slope on the structure and properties of neutron stars are investigated. In particular, the effect on the radius, on the particle fractions, and on the onset of the nuclear direct Urca processes is discussed. It is shown that the improved model is in accordance with GW170817 observations, and that the constrained symmetry energy does not allow for nucleonic direct Urca processes inside neutron stars. Within the present model, no hyperons nucleate inside neutron stars. [ABSTRACT FROM AUTHOR]

Heavy-quark spin symmetry is explicitly broken by the mass splitting between a heavy-light pseudoscalar meson and its vector partner. This fact plays a pivotal role in the physics of states whose mass lies close to the threshold of an open-flavor meson pair, like X(3872). We show that this source of heavy-quark spin symmetry breaking can be systematically included within the diabatic representation of the Born-Oppenheimer approximation. We verify that including all the appropriate coupled channels guarantees conservation of total angular momentum, parity, and charge-conjugation parity. This marks a fundamental step towards a unified, first-principles study of quarkonia and meson molecules with hidden flavor. [ABSTRACT FROM AUTHOR]

Arc plasma is the heat source in electrical discharge machining (EDM), it affects the material removal and discharge crater formation directly, so it is necessary to clarify its characteristics. However, it is challenging to understand the physical mechanisms behind each pulse discharge through experimental methods, as it is a transient, multi-physical process that occurs in a very short time and small gap. In this paper, a two-temperature model was proposed to investigate the characteristics of the arc plasma and the energy distribution considering the multi-physics fields in the steady state. In this model, the electrons and the heavy species of the arc plasma were considered separately in the energy conservation equations, so that the temperature of the electrons and heavy species can be calculated separately. Besides, the velocity distribution, pressure distribution, electrical potential distribution, and diameter of the arc plasma, as well as the heat flux distribution and the energy distribution into the anode and cathode were analyzed. Then the variations in arc plasma properties and energy distribution with different discharge conditions were studied. The results showed that, at a lower discharge current, the electron temperature was higher than the heavy species temperature, which means that the arc plasma did not reach a local thermodynamic equilibrium (LTE) state under these discharge conditions. To validate the simulation results, the arc plasma was observed with a high-speed camera, and the diameter of craters on the surface of both the cathode and anode was measured with single-pulse discharge experiments. The experiment results were consistent with the simulation results. • A two-temperature model was established to study the arc plasma in EDM. • The temperature of electrons and heavy species of arc plasma was obtained. • The arc plasma did not reach the local thermodynamic equilibrium state under the given simulation conditions. • The energy distribution ratio into the anode, cathode, and dielectric were calculated, respectively. • The arc plasma characteristics and the energy distribution under different discharge conditions were studied. [ABSTRACT FROM AUTHOR]

In this paper, we have obtained the analytical and numerical mass spectra of the charmonium and bottomonium mesons using the non-relativistic Schrödinger equation under a spin–spin, spin–orbit and tensor coupled Cornell potential energy. We adopted the Wentzel–Kramers–Brilluoin approximation method to obtain the energy bound equation in closed form. We obtained the potential free parameters by fitting the mass spectra equation to the experimental data of the Particle Data Group. The hyperfine mass splitting of the mesons are obtained for different singlet ( s = 0) and triplet ( s = 1) quantum states ( n 2 s + 1 l j) . Also, the hyperfine multiplet splitting for l > 0 and total angular momentum quantum number j = l , j = l ± 1 were obtained. The results revealed that the charmonium masses ψ (n 3 S 1) and η c (n 1 S 0) ( n = 2 , 3 , 4 , 5 , 6) and bottomonium masses ( η b (n 1 S 0)) and Υ (n 3 S 1) ( n = 2 , 3 , 4 , 6) for the s-wave quantum states are in good agreement with the results obtained by other methods in the existing literature and available experimental data. For l > 0 , the charmonia masses χ c j (n 3 P j) ψ 1 1 3 D 1 and ψ 2 2 3 D 1 agreed with the works obtained using other potential models and observed data. In comparison to experimental data, the total absolute deviation error of 3.21% and 1.06% was obtained for the respective charmonium and bottomonium masses. The proposed potential model provides a satisfying account for the mass spectra of the heavy mesons and may be extended to study other spectroscopic parameters. [ABSTRACT FROM AUTHOR]

We present differential cross sections and photon beam asymmetries of photoproduction reactions of η mesons in the center-of-mass energy of 1.82 < W < 2.32 measured in LEPS2/BGOegg experiment. The differential cross section at cos θ c. m. η < - 0.6 shows a bump structure at W ∼ 2.2 GeV, suggesting the appearance of the baryon resonances with hidden s s ¯ . The photon beam asymmetries at W > 2.1 GeV were measured for the first time. [ABSTRACT FROM AUTHOR]

We study the properties of pseudoscalar mesons, pion, kaon, η and η ′ , and compute the γ ∗ γ → π 0 , η , η ′ transition form factor in the framework of the Schwinger–Dyson equations and Bethe–Salpeter equations, using a momentum independent contact interaction. The contact interaction is capable to describe the observable properties, but produces a transition form factor whose evolution for large Q 2 disagrees with experiment and perturbative QCD. Invited contribution to a Special Issue of Few Body Systems: "Emergence and Structure of Baryons—Selected Contributions from the International Conference Baryons 2022" [ABSTRACT FROM AUTHOR]

Pseudoscalar meson dominance has implications for nucleon structure which follow from an Extended Partial Conservation of the Axial Current (EPCAC). The minimal resonance saturation of the nucleon pseudoscalar form factor of the lowest pseudoscalar and isovector mesons compatible with pQCD short distance constraints and chiral symmetry. Using PDG masses and widths we obtain g π N N = 13.21 (- 0.06 + 0.11) , to be compared with the most precise determinations from np, pp scattering, g π + n p = 13.25 (5) from the Granada-2013 database. Equivalently a Goldberger–Treiman discrepancy Δ GT = 1. 8 - 0.4 + 0.9 % is found. Our results are consistent with almost flat strong pion-nucleon-nucleon vertices. [ABSTRACT FROM AUTHOR]

Hadronization, which is the process by which an energetic colored quark evolves into a color-singlet hadron in Quantum Chromodynamics, can be studied both in small nuclei and large nuclei, and the comparison of the differences between those two systems provides information about the hadronization mechanisms on femtometer distance scales. It can be argued that this process is well understood for light meson production on nuclei, but data from HERMES and CLAS for baryon production present puzzling patterns that are not well described by models. Herein we suggest that this might be due to the presence of diquarks in the protons and neutrons making up these nuclei. [ABSTRACT FROM AUTHOR]

The Dirac equation (DE) plays an essential role in the relativistic quantum systems, which is reduced to a form similar to Schrödinger equation when a certain potential's type is selected as the Cornell potential. By choosing the generalized fractional derivative, the fractional Nikiforov–Uvarov method is applied as a good efficient tool. The energy eigenvalues and corresponding wave functions are obtained in the sense of fractional forms by solving DE analytically. The special case is obtained, which is compatible with the classical model. In addition, we applied the present results on the light mesons such as D , D s and B s. Solving the fractional DE will open a new path to solve and improve results in the classical relativistic quantum systems. [ABSTRACT FROM AUTHOR]

Recently, the BESIII Collaboration reported that there exist two explicit enhancement structures near 2.25 GeV, one has the mass of M = 2 2 3 2 ± 1 9 ± 2 7 MeV and the width of Γ = 9 3 ± 5 3 ± 2 0 MeV and another structure has the mass of M = 2 2 0 0 ± 1 1 ± 1 7 MeV and the width of Γ = 7 4 ± 2 0 ± 2 4 MeV when analyzing the cross section of subprocesses. Earlier, the BESIII Collaboration reported the existence of the X (2 2 2 0) , with a mass of 2 2 2 2 ± 7 ± 2 MeV and width of 5 9 ± 3 0 ± 6 MeV. Based on these experimental results, we carried out a study. We present the comparison of the mass spectrum between theoretical and experimental masses and examine the two-body strong decays of these states within two different approaches to the 3 P 0 model. We find that the newly discovered states are most likely to be an ω (3 D) state. This discovery could be useful in establishing entire ω mesons. [ABSTRACT FROM AUTHOR]

In this paper, we consider the soft-wall holographic model with the linear dilaton background. The model leads to a Hydrogen-like meson spectrum which can be interpreted as the static limit with very large quark masses when the Coulomb interaction dominates. The mass scale introduced by the linear dilaton is matched to the quark mass. The resulting model is analyzed for the scalar, vector and tensor cases. The electromagnetic coupling constants predicted by the model are decreasing with the radial number in contrast to the soft-wall model with quadratic dilaton where these couplings represent a universal constant. The given prediction is qualitatively consistent with the corresponding experimental data in vector quarkonia. The proposed model can thus be used as a constituent part of more elaborated holographic models for heavy quarkonia. A particular example of such a model is put forward. [ABSTRACT FROM AUTHOR]

We investigate the weak leptonic and semileptonic decay widths of pseudoscalar light and heavy mesons in a Dirac formalism. We take relativistic-independent quark model of the form V q (r) = 1 2 (1 + γ 0) (a 2 r + V 0) , where a > 0. This is computed using the binding quark eigenfunction and taking the assumptions of a significant relationship between the quark and antiquark momenta inside the decaying meson in the rest frame. To calculate the decay constant (f M) , decay width and branching fractions of pseudoscalar mesons, we employ the model parameters that we used earlier. The experimental findings and various similar models are in good agreement with our predictions such as " f B C > f B S > f B , f D S > f D , f D > f B and f B > f π ". Finally, we calculate the form factors and branching fractions for the semileptonic D (D 0) decays " D + → K S 0 e + ν e ,  D + → K L 0 e + ν e ,  D + → π 0 e + ν e ,  D 0 → K − e + ν e and D 0 → π − e + ν e " and find reasonable agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Corrections to the Wess–Zumino–Witten anomaly caused by the explicit breaking of the chiral symmetry are studied using the effective meson Lagrangian based on the Nambu–Jona-Lasinio model with the simultaneous expansion in derivatives, current quark masses, and 1/Nc powers. The leading contribution and the first correction for the amplitudes of the π0, η, η' → γγ decays and the contact term in the amplitudes have been calculated. The results are compared with similar 1/Nc chiral perturbation calculations and existing experimental data. [ABSTRACT FROM AUTHOR]

The new relativistic semiclassical leptonic decay widths of vector mesons as the relativistic systems of two quarks with arbitrary masses interacting by means of the funnel-type potentials with Coulomb interaction are obtained. The behavior of the relativistic leptonic decay widths of vector mesons is investigated. Comparison of the behavior for new expression with its relativistic spinless analog is given. Consideration is conducted within the framework of completely covariant quasipotential approach in the Hamiltonian formulation of quantum field theory via a transition to the relativistic configurational representation in the case of two relativistic spin particles of arbitrary masses. [ABSTRACT FROM AUTHOR]

In this work, we evaluated the widths of the pionic and radiative transitions from the T c s ¯ 0 + (2900) to the D s 1 + (2460) in the D s 1 + (2460) molecular frame and the D s 1 + (2460) charmed-strange meson frame. Our estimations demonstrate that the transition widths in the D s 1 + (2460) molecular frame are much larger than those in the the D s 1 + (2460) charmed-strange meson frame. Specifically, the ratio of the widths of Γ (T c s ¯ 0 + (2900) → D s 1 + π 0) and Γ (T c s ¯ 0 + (2900) → D + (0) K 0 (+)) is estimated to be around 0.1 in the D s 1 + (2460) charmed-strange meson frame, whereas the lower limit of this ratio is 0.67 in the D s 1 + (2460) molecular frame. Thus, the aforementioned ratio could be employed as a tool for testing the nature of the D s 1 + (2460) . [ABSTRACT FROM AUTHOR]

The decay B 0 → D ∗ + D - is favorable mode for studying CP violation in the interference between mixing and decay for B 0 and B ¯ 0 mesons. The latest analysis of the CP parameters has been performed by the LHCb Collaboration values of S D ∗ D = - 0.861 ± 0.077 ± 0.019 , C D ∗ D = - 0.059 ± 0.092 ± 0.020 , ▵ S D ∗ D = 0.019 ± 0.075 ± 0.012 , ▵ C D ∗ D = - 0.031 ± 0.092 ± 0.016 , and A D ∗ D CP = 0.008 ± 0.014 ± 0.006 ± 0.003 . We have been estimated the parameters S D ∗ D and C D ∗ D of the B 0 → D ∗ + D - decay as - 0.709 ± 0.024 and - 0.051 ± 0.004 . In the following, we have obtained the values of ▵ S D ∗ D = 0.054 ± 0.003 and ▵ C D ∗ D = 0.020 ± 0.001 and direct CP violation of 0.008 ± 0.001 . Also, we have calculated the branching ratio of B 0 → D ∗ + D - decay. The values obtained in this work are comparable with the corresponding experimental values. [ABSTRACT FROM AUTHOR]

Multi-particle states with additional pions are expected to result in a difficult-to-control excited-state contamination in lattice simulations. We show that heavy meson chiral perturbation theory can be employed to estimate the contamination due to two-particle B π states in various B-meson observables, like the B-meson decay constant and the B ∗ B π coupling. We work in the static limit and to next-to-leading order in the chiral expansion, i.e. including O (p). The B π states are found to typically lead to an overestimation of the observables at the few percent level. We determine two of the LECs from B → π form factor computations of the KEK group (Colquhoun et al. in Phys. Rev. D 106:054502, 2022) and discuss ways to determine the others. In particular, one LEC which is associated with smeared interpolating fields seems to be easily accessible and thus opens up a way to systematically study the effect of smearing on excited-state effects. [ABSTRACT FROM AUTHOR]