Search

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]

The associated production of prompt J/ψ and Υ mesons in pp collisions at a centre-of-mass energy of s = 13 TeV is studied using LHCb data, corresponding to an integrated luminosity of 4 fb−1. The measurement is performed for J/ψ (Υ) mesons with a transverse momentum pT< 10 (30) GeV/c in the rapidity range 2.0 < y < 4.5. In this kinematic range, the cross-section of the associated production of prompt J/ψ and Υ(1S) mesons is measured to be 133 ± 22 ± 7 ± 3 pb, with a significance of 7.9 σ, and that of prompt J/ψ and Υ(2S) mesons to be 76 ± 21 ± 4 ± 7 pb, with a significance of 4.9 σ. The first uncertainty is statistical, the second systematic, and the third due to uncertainties on the used branching fractions. This is the first observation of the associated production of J/ψ and Υ(1S) in proton-proton collisions. Differential cross-sections are measured as functions of variables that are sensitive to kinematic correlations between the J/ψ and Υ(1S) mesons. The effective cross-sections of the associated production of prompt J/ψ and Υ mesons are obtained and found to be compatible with measurements using other particle productions. [ABSTRACT FROM AUTHOR]

We investigate the differences between the light-cone distribution amplitudes (LCDAs) of Bs mesons and Bq mesons (with q = u, d) induced by a non-vanishing strange-quark mass ms ≠ 0 (compared to mq ≃ 0). To this end, we consider the so-called "radiative tail" which is related to the short-distance expansion of the relevant light-ray operators in heavy-quark effective theory. We extend the calculation of the according matching coefficients, including operators linear in ms for both the leading and sub-leading 2-particle LCDAs. Based on a generic parameterization for the leading LCDA, we discuss the effect on its shape on a quantitative level, and compare our findings with recent results on the inverse moments of the Bq and Bs LCDAs from QCD sum rules. [ABSTRACT FROM AUTHOR]

The branching fractions of τ → π + π − π − ν τ and τ → π − 2 π 0 ν τ are calculated within the chiral NJL model. Features of the axial-vector a 1 meson which play an important role in describing the τ decays are discussed. Permissible values for the mass and width of the a 1 meson are considered in accordance with the latest experiments. [ABSTRACT FROM AUTHOR]

The mass and decay of the ss̅ member of the 1³F4 meson nonet are investigated in the framework of the Regge phenomenology and the 3P0 model. We propose, based on the results, that the assignment of the ss̅ member of the 1³F4 meson nonet will require additional testing in the future. Our results also provide information for future studies of the 1³F4 meson nonet. [ABSTRACT FROM AUTHOR]

We investigate the unpolarized transverse momentum dependent (TMD) structure of light mesons at low Q 2 scales in nonperturbative region of quantum chromodynamics (QCD). To this end, we calculate the unpolarized TMD valence quark distribution functions of pion and kaon based on the covariant parton model in which the flavour dependent covariant momentum distribution of quarks is needed. We apply the statistical model for this momentum distribution, for the first time, and also consider the quarks to be massive. The results of TMD valence distributions of light mesons show convenient general properties. We also obtain the integrated valence quark distributions of pion and kaon and compare our results with those of other models. [ABSTRACT FROM AUTHOR]

The very rare D ∗ (2007) 0 → μ + μ - decay is searched for by analysing B - → π - μ + μ - decays. The analysis uses a sample of beauty mesons produced in proton–proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 \,fb - 1 . The signal signature corresponds to simultaneous peaks in the μ + μ - and π - μ + μ - invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at B (D ∗ (2007) 0 → μ + μ -) < 2.6 × 10 - 8 at 90 % confidence level. This is the first limit on the branching fraction of D ∗ (2007) 0 → μ + μ - decays and the most stringent limit on D ∗ (2007) 0 decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays. [ABSTRACT FROM AUTHOR]

We study the pion electromagnetic form factor in the modulus squared dispersion relation, and do the model independent extraction of the chiral mass embedded in the sub-leading twist light-cone distribution amplitude. The motivation of this work is the recent measurement of timelike form factor in the resonant regions, which makes up the piece lacking solid QCD-based calculation. With the perturbative QCD calculation up to next-to-leading-order of strong coupling and twist four level of meson distribution amplitudes, we obtain the chiral mass of pion meson as m 0 π (1 GeV) = 1. 31 - 0.30 + 0.27 GeV . Due to the chiral enhancement contribution from the sub-leading twist distribution amplitudes in the perturbative QCD calculation, we can not extract the lowest Gegenbauer moments of pion from the study of electromagnetic form factor. This problem could be settled down with the foresee Belle-II and BESIII measurement of the transition form factor especially in the large momentum transfers regions. [ABSTRACT FROM AUTHOR]

The measurement of charmonium states produced in proton-neon ( p Ne ) collisions by the LHCb experiment in its fixed-target configuration is presented. The production of J / ψ and ψ (2 S) mesons is studied with a beam of 2.5 Te V protons colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy s NN = 68.5 Ge V . The data sample corresponds to an integrated luminosity of 21.7 ± 1.4 nb - 1 . The J / ψ and ψ (2 S) hadrons are reconstructed in μ + μ - final states. The J / ψ production cross-section per target nucleon in the centre-of-mass rapidity range y ⋆ ∈ [ - 2.29 , 0 ] is found to be 506 ± 8 ± 46 nb/nucleon . The ratio of J / ψ and D 0 cross-sections is evaluated to (1.06 ± 0.02 ± 0.09) % . The ψ (2 S) to J / ψ relative production rate is found to be (1.67 ± 0.27 ± 0.10) % in good agreement with other measurements involving beam and target nuclei of similar sizes. [ABSTRACT FROM AUTHOR]

Using a non-relativistic potential model, we obtain the mass spectra, leptonic decay constants, and parameters of the Isgur-Wise function for the beauty and charm mesons. With the calculated quantities, we investigate purely leptonic decays of B + , B ∗ , B c + , semileptonic decay modes B (s) → D (s) l ν and B c → η c ℓ ν ¯ for three lepton channels e , μ , τ , and obtain the corresponding branching fractions. B ¯ (s) → D (s) ∗ l ν ¯ transitions are also studied. Next, we apply the form factors for spin zero and spin one transitions of B c to calculate the nonleptonic branching ratios of B c → J / ψ (η c) + P (V) , where P and V stand for the D q ∗ - vector meson and the D q pseudoscalar meson, respectively. Our results are found to be in agreement with those obtained in the experimental and theoretical results. [ABSTRACT FROM AUTHOR]

We reconsider the semileptonic decays of B → D 1 (′) l ν ¯ l . The previous theoretical calculations predict a significantly smaller rate for the semileptonic decay of B to D 1 ′ (J l = 1 2) compared with that to the D 1 (J l = 3 2) , which is not consistent with the current experimental data. This conflict is known as the so-called ' 1 2 vs. 3 2 puzzle'. In this work, we propose a simple scheme to fix this problem, where we suppose the strong eigenstates D 1 (′) that do not coincide with the eigenstate of the weak interaction, since no experimental results show that the weak and the strong interactions have to share the same eigenstates. Within the framework of this tentative scheme, meson B first weakly decays to the weak eigenstates D α (β) and then the latter are detected as the D 1 (′) by the strong decay products D * π . We predict that there exist two new particles D α (β) with J P = 1 + , which were not previously identified. The good performance of the new scheme in describing the experimental data may hint at new symmetry in the weak decays of B q to 1 + heavy–light mesons. To test the scheme proposed here, we suggest an experiment to detect the difference in the invariant mass spectra of D 1 that is reconstructed from the B weak decay and from the strong decay products. [ABSTRACT FROM AUTHOR]

First physics results of the BM@N experiment at the Nuclotron/NICA complex are presented on π+ and K+ meson production in interactions of an argon beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 A GeV. Transverse momentum distributions, rapidity spectra and multiplicities of π+ and K+ mesons are measured. The results are compared with predictions of theoretical models and with other measurements at lower energies. [ABSTRACT FROM AUTHOR]

We present a method to compute the responses of meson screening masses to the chemical potential by Taylor expanding the correlator using lattice QCD simulation. We start by comparing the free theory lattice results with the analytical expression. Then, using symmetry arguments, we obtain an expression for the correlator in a series of the chemical potential at finite temperature. Using this, we obtain the lowest order correction to the screening mass at a finite chemical potential for temperatures around 2.5 GeV. Our lattice analysis is limited to isoscalar chemical potential for the pseudoscalar channel. The calculations were performed using (2+1)-flavors of the Highly Improved Staggered Quark (HISQ/tree) action, with the ratio of the strange quark mass to the light quark mass ms/mℓ = 20 corresponding to pion masses of 160 MeV. [ABSTRACT FROM AUTHOR]

We address the nonperturbative calculation of the inclusive decay rate of semileptonic B(s)-meson decays from lattice QCD. Precise Standard-Model predictions are key ingredients in searches for new physics, and this type of computation may eventually provide new insight into the long-standing tension between the inclusive and exclusive determinations of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements |Vcb| and |Vub|. We present results from a pilot lattice computation for Bs → Xclνl, where the initial b quark described by the relativistic-heavy-quark (RHQ) formalism on the lattice and the other valence quarks discretised with domain-wall fermions are simulated approximately at their physical quark masses. We compare two different methods for computing the decay rate from lattice data of Euclidean n-point functions, namely Chebyshev and Backus-Gilbert approaches. We further study how much the ground-state meson dominates the inclusive decay rate and indicate our strategy towards a computation with a more comprehensive systematic error budget. [ABSTRACT FROM AUTHOR]

The production of inclusive, prompt and non-prompt J/ψ was studied for the first time at midrapidity (−1.37 < ycms< 0.43) in p-Pb collisions at s NN = 8.16 TeV with the ALICE detector at the LHC. The inclusive J/ψ mesons were reconstructed in the dielectron decay channel in the transverse momentum (pT) interval 0 < pT< 14 GeV/c and the prompt and non-prompt contributions were separated on a statistical basis for pT> 2 GeV/c. The study of the J/ψ mesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of 689 ± 13 μb−1. The proton-proton reference cross section for inclusive J/ψ was obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing the pT-differential J/ψ production cross sections. The pT-differential nuclear modification factors RpPb of inclusive, prompt, and non-prompt J/ψ are consistent with unity and described by theoretical models implementing only nuclear shadowing. [ABSTRACT FROM AUTHOR]

The CKM angle γ is determined from CP-violating observables measured in B± → D[K∓π±π±π∓]h±, (h = K, π) decays, where the measurements are performed in bins of the decay phase-space of the D meson. Using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to a total integrated luminosity of 9 fb−1, γ is determined to be γ = 54.8 + 6.0 − 5.8 + 0.6 − 0.6 + 6.7 − 4.3 ∘ , where the first uncertainty is statistical, the second systematic and the third from the external inputs on the coherence factors and strong phases of the D-meson decays. [ABSTRACT FROM AUTHOR]

The first observation of the B s 0 → D∗+D∗− decay and the measurement of its branching ratio relative to the B0→ D∗+D∗− decay are presented. The data sample used corresponds to an integrated luminosity of 9 fb−1 of proton-proton collisions recorded by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018. The decay is observed with more than 10 standard deviations and the time-integrated ratio of branching fractions is determined to be B B s 0 → D ∗ + D ∗ − B B 0 → D ∗ + D ∗ − = 0.269 ± 0.032 ± 0.011 ± 0.008 , where the first uncertainty is statistical, the second systematic and the third due to the uncertainty of the fragmentation fraction ratio fs/fd. The B s 0 → D*+D*− branching fraction is calculated to be B B s 0 → D ∗ + D ∗ − = 2.15 ± 0.26 ± 0.09 ± 0.06 ± 0.16 × 10 − 4 , where the fourth uncertainty is due to the B0→ D*+D*− branching fraction. These results are calculated using the average B s 0 meson lifetime in simulation. Correction factors are reported for scenarios where either a purely heavy or a purely light B s 0 eigenstate is considered. [ABSTRACT FROM AUTHOR]

We use a recent lattice determination of the vector and axial Ds → γ form factors at high squared momentum transfer q2 to infer their Bs → γ counterparts. To this end, we introduce a phenomenological approach summarized as follows. First, we describe the lattice data with different fit templates motivated by vector-meson dominance, that is expected to hold in the high-q2 region considered. We identify reference fit ansaetze with one or two physical poles, that we validate against alternative templates. Then, the pole residues can be unambiguously related to the appropriate couplings involving the pseudoscalar, the vector mesons concerned, and the photon — or tri-couplings — and the latter can be expressed as sums over quark magnetic moments, weighed by their e.m. charges. This description obeys a well-defined heavy-quark scaling, that allows to parametrically scale up the form factors to the Bs → γ case. We discuss a number of cross-checks of the whole approach, whose validation rests ultimately in a first-principle determination, e.g. in lattice QCD. Finally, we use our obtained form factors to reassess the SM prediction of ℬ(Bs → μ+μ−γ) in the range q 2 ∈ [4.2, 5.0] GeV, where an experimental measurement is awaited. [ABSTRACT FROM AUTHOR]

The ratio of branching fractions of B c + → B s 0 π + and B c + → J / ψ π + decays is measured with proton-proton collision data of a centre-of-mass energy of 13 TeV. The data were collected with the LHCb experiment during 2016–2018, corresponding to an integrated luminosity of 5.4 fb−1. The B s 0 mesons are reconstructed via the decays B s 0 → J / ψϕ and B s 0 → D s − π + . The ratio of branching fractions is measured to be B B c + → B s 0 π + / B B c + → J / ψ π + = 91 ± 10 ± 8 ± 3 where the first uncertainty is statistical, the second is systematic and the third is due to the knowledge of the branching fractions of the intermediate state decays. [ABSTRACT FROM AUTHOR]

The production cross-sections of Υ mesons, namely Υ(1S), Υ(2S) and Υ(3S), in pp collisions at s = 5 TeV are measured with a data sample corresponding to an integrated luminosity of 9.13 ± 0.18 pb−1 collected by the LHCb detector. The Υ mesons are reconstructed in the decay mode Υ → μ+μ−. Double differential cross-sections times branching fractions, as functions of the transverse momentum pT and the rapidity y of the Υ mesons, are measured in the range pT< 20 GeV/c and 2.0 < y < 4.5. The results integrated over these pT and y ranges are σ Υ 1 S × B Υ 1 S → μ + μ − = 2101 ± 33 ± 83 pb , σ Υ 2 S × B Υ 2 S → μ + μ − = 526 ± 20 ± 21 pb , σ Υ 3 S × B Υ 3 S → μ + μ − = 242 ± 16 ± 10 pb , where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different Υ states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of Υ(1S) at s = 5 TeV is updated as well using the directly measured cross-section results from this analysis. [ABSTRACT FROM AUTHOR]

In this paper, we study the processes of e+e− annihilation into two body final states, either two pseudoscalar mesons or one meson with a photon. The hadronic vacuum polarization form factors are calculated within the framework of resonance chiral theory in the energy region of E ≲ 2 GeV, with final state interactions taken into account. A joint analysis on the processes of e+e−→ π+π−, K+K−, K L 0 K S 0 , π0γ, and ηγ has been performed, and the latest experimental data are included. Based on the vacuum polarization form factors of these processes, we estimate their contributions to the lowest order of anomalous magnetic moment of the muon, (g – 2)μ. Combined with other contributions from hadronic vacuum polarization and other interactions from the standard model, the discrepancy between theoretical prediction and experimental measurement is ∆aμ = (24.1 ± 5.4) × 10−10, i.e., 4.5σ. [ABSTRACT FROM AUTHOR]

I describe the history of the calculations of NLO and NNLO QCD corrections to weak decays of mesons, particle–antiparticle mixing and electric dipole moments (EDMs) in the period 1988–2023. Also existing calculations of electroweak and QED corrections to these processes are included in this presentation. These efforts bear some analogies to the climbing of Himalayas and various expeditions by several teams of strongly motivated "climbers" allowed to move this field from the LO through the NLO to the NNLO level. We also summarize the most recent calculations within the Standard Model Effective Field Theory. The material is meant to be an up to date review of this very advanced field in non-technical terms as much as possible and a guide to the rich literature on NLO and NNLO corrections in question. In particular we stress for which processes these calculations are crucial for the tests of the Standard Model and to be able to differentiate between numerous New Physics models. It includes also several anecdotes related to the climbs that I was involved in. I hope that some of the comments made in the course of the presentation could turn out to be not only amusing but also instructive. [ABSTRACT FROM AUTHOR]

In this paper, we review our findings concerning fractal entropy of microscopic configurations corresponding to the production of K S 0 mesons in AuAu collisions in the z-scaling approach. The entropy is expressed via structural and fragmentation fractal dimensions, and model parameter c AuAu is interpreted as a specific heat of produced medium. These parameters are related to the respective momentum fractions of the colliding nuclei, the momentum fractions of the scattered constituents that fragment into the produced hadrons, and the multiplicity density of negative particles in the central interaction region. The dependence of the entropy on the collision energy over the range of 7.7–200 GeV for most central and most peripheral events is studied as a function of the transverse momentum of the produced K S 0 mesons. A non-trivial dependence of the entropy on the collision energy with decreasing transverse momentum is found. This reflects the irregularity of the behavior of the specific heat, c AuAu , and can point to a manifestation of phase transition in nuclear matter. [ABSTRACT FROM AUTHOR]

In this paper, we study total and differential observables of electro- and photoproduction of light ρ , ω and ϕ mesons as functions of the center-of-mass energy of the γ p collision and momentum transfer squared |t|. The corresponding vector mesons wave functions have been computed in the framework of relativistic AdS/QCD holographic approach. A satisfactory description of all available data on ground-state ρ (1 S) , ω (1 S) and ϕ (1 S) mesons production cross sections has been achieved in the color dipole picture. Finally, the key observables of excited ρ (2 S) , ω (2 S) and ϕ (2 S) states production in γ (∗) p collisions have been presented here using a common wave function formalism. This study reveals a large theoretical uncertainty coming from the modeling of the partial dipole amplitude in the nonperturbative kinematical domain. Hence, the latter could benefit from future measurements of photoproduction of the excited states. [ABSTRACT FROM AUTHOR]

We investigate the mass spectrum and the decay properties of the B s mesons within the screened nonrelativistic quark model and the 3 P 0 model. Our results suggest that the B sJ (6064) and B sJ (6114) states, as the first solution of the recently LHCb measurements, could be explained as the B s (1 3 D 3) and B s (1 3 D 1) , respectively. In addition, the B sJ (6109) and B sJ (6158) states, as the second solution of the LHCb measurements, could be explained as the B s 2 ′ (1 D) and B s 1 (2 P) , respectively. Meanwhile, the B s 1 (5830) could be interpreted as the candidate of the B s 1 (1 P) . We also calculated the decay properties of the other excited B s mesons with the predicted masses, which should be helpful for the experimental searching in future. [ABSTRACT FROM AUTHOR]

A measurement of D 0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of D 0 mesons is studied with a beam of 2.5 Te V protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of s NN = 68.5 Ge V . The sum of the D 0 and D ¯ 0 production cross-section in p Ne collisions in the centre-of-mass rapidity range y ⋆ ∈ [ - 2.29 , 0 ] is found to be σ D 0 y ⋆ ∈ [ - 2.29 , 0 ] = 48.2 ± 0.3 ± 4.5 μ b / nucleon where the first uncertainty is statistical and the second is systematic. The D 0 - D ¯ 0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative y ⋆ . The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1 % intrinsic charm and 10 % recombination contributions better describe the data than the other models considered. [ABSTRACT FROM AUTHOR]

In this paper we analyze the photoproduction of heavy quarkonia pairs which include b-quarks, such as B c + B c - -mesons or charmonium-bottomonium pairs. Compared to charmonia pair production, these channels get contributions only from some subsets of diagrams, and thus allow for a better theoretical understanding of different production mechanisms. In contrast to the production of hidden-flavor quarkonia, for the production of B c -meson pairs there are no restrictions on internal quantum numbers in the suggested mechanisms. Using the Color Glass Condensate approach, we estimated numerically the production cross-sections in the kinematics of the future electron–hadron colliders and the ultraperipheral collisions at LHC. We found that the production of J / ψ η c and B c + B c - meson pairs are the most promising channels for studies of quarkonia pair production. [ABSTRACT FROM AUTHOR]

In this work, we investigate the form factors of B c decays into J / Ψ , ψ (2 S , 3 S) , η c , η c (2 S , 3 S) , χ c 0 , χ c 1 , h c , and X(3872) mesons in the covariant light-front quark model (CLFQM). For the purpose of the branching ratio calculation, the form factors of B c → D (∗) , D s (∗) transitions are also included. In order to obtain the form factors for the physical transition processes, we need to extend these form factors from the space-like region to the time-like region. The q 2 dependence for each transition form factor is also plotted. Then, using the factorization method, we calculate the branching ratios of 80 B c decay channels with a charmonium involved in each mode. Most of our predictions are comparable to the results given by other approaches. As to the decays with the radially excited-state S-wave charmonia involved, such as ψ (2 S , 3 S) and η c (2 S , 3 S) , two sets of parameters for their light-front wave functions, corresponding to scenario I (SI) and scenario II (SII), are adopted to calculate the branching ratios. By comparing with the future experimental data, one can discriminate which parameters are more favored. [ABSTRACT FROM AUTHOR]

In the QCD-like effective model, the Polyakov linear-sigma model, the isospin sigma field ( σ ¯ 3 = f K ± − f K 0 ) and the third generator of the matrix of the explicit symmetry breaking [ h 3 = m a 0 2 f K ± − f K 0 ] are estimated in terms of the decay constants of the neutral ( f K 0 ) and charged Kaon ( f K ± ) and the mass of a 0 meson. Both quantities σ ¯ 3 and h 3 are then evaluated, at finite baryon ( μ B ), isospin chemical potential ( μ I ), and temperature (T). Thereby, the dependence of the critical temperature on isospin chemical potential could be mapped out in the ( T − μ I ) phase diagram In the QCD-like effective model, the Polyakov linear-sigma model, the isospin sigma field ( σ ¯ 3 = f K ± − f K 0 ) and the third generator of the matrix of the explicit symmetry breaking [ h 3 = m a 0 2 f K ± − f K 0 ] are estimated in terms of the decay constants of the neutral ( f K 0 ) and charged Kaon ( f K ± ) and the mass of a 0 meson. Both quantities σ ¯ 3 and h 3 are then evaluated, at finite baryon ( μ B ), isospin chemical potential ( μ I ), and temperature (T). Thereby, the dependence of the critical temperature on isospin chemical potential could be mapped out in the ( T − μ I ) phase diagram. The in-medium modifications of pseudoscalars ( J p c = 0 − + ), scalars ( J p c = 0 + + ), vectors ( J p c = 1 − − ), and axial-vectors ( J p c = 1 + + ) meson states are then analyzed in thermal and dense medium. We conclude that the QCD phase diagram ( T − μ I ) is qualitatively similar to the ( T − μ B ) phase diagram. We also conclude that both temperature and isospin chemical potential enhance the in-medium modifications of the meson states a 0 , σ , η ′ , π , f 0 , κ , η , K, ρ , ω , κ * , ϕ , a 1 , f 1 , K * , and f 1 * . Regarding their chemical potential, at high temperatures the various meson states likely dissolve into colored partonic phase. In this limit, the meson masses form a universal bundle. Thus, we conclude that the increase in the chemical potential similar to temperature derives the colorless confined meson states into the colored deconfined parton phase. [ABSTRACT FROM AUTHOR]

As known, the realistic, exponential, fall-off of the rate of production of light mesons in the chromo-electric field of a quark–antiquark string, as a function of the meson mass, can be obtained from the Schwinger-formula Gaussian fall-off within a phenomenological approach which assumes a certain distribution of the string tension. This approach gets a clear meaning in the London limit of the dual superconductor, where the logarithmic increase of the chromo-electric field towards the core of the string leads precisely to the change of the Gaussian fall-off to the exponential one, thus allowing for an identification of the phenomenological distribution of the string tension. In this paper, we demonstrate that, for this distribution of the string tension, the distribution of large-size Yang–Mills instantons, which are interacting with the confining monopole background, becomes O (1 / ρ 3) , where ρ is the size of an instanton. Since such a distribution of large-size instantons is known to yield confinement, we conclude that, in the London limit of the dual-superconductor vacuum, instantons can form a confining medium, and we evaluate their contribution to the total string tension. [ABSTRACT FROM AUTHOR]

Based on the effective Lagrangian in the heavy quark limit, we calculate the one-boson-exchange interaction kernel of P ψ N 4312 + as the D ¯ Σ c molecular state in isospin- 1 2 . We present the Bethe-Salpeter equation and wave function for the constituent particles to be a (pseudo)scalar meson and a 1 2 baryon. By solving the Bethe-Salpeter equation, we obtain P ψ N 4312 + as the D ¯ Σ c molecular state with JP = 1 2 − . Combining the effective Lagrangian and the obtained BS wave function, the partial decay widths of P ψ N 4312 + to J/ψp, ηcp, D ¯ ∗ 0 Λ c + and D ¯ 0 Λ c + are calculated to be 0.17, 0.085, 8.8, and 0.026 MeV, respectively, which are roughly consistent with the LHCb experimental measurements and some other theoretical researches. The obtain results indicate the fraction of D ¯ ∗ 0 Λ c + channel amounts to ~ 90% of P ψ N 4312 + , and is a highly promising channel to be discovered in the near future experiments. Our results favor the interpretation of P ψ N 4312 + as the D ¯ Σ c molecular state with JP = 1 2 − and isospin I = 1 2 . [ABSTRACT FROM AUTHOR]

The cross-sections of exclusive (coherent) photoproduction J/ψ and ψ(2S) mesons in ultra-peripheral PbPb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV are measured using a data sample corresponding to an integrated luminosity of 228 ± 10 μb−1, collected by the LHCb experiment in 2018. The differential cross-sections are measured separately as a function of transverse momentum and rapidity in the nucleus-nucleus centre-of-mass frame for J/ψ and ψ(2S) mesons. The integrated cross-sections are measured to be σ J / ψ coh = 5.965 ± 0.059 ± 0.232 ± 0.262 mb and σ ψ 2 S coh = 0.923 ± 0.086 ± 0.028 ± 0.040 mb, where the first listed uncertainty is statistical, the second systematic and the third due to the luminosity determination. The cross-section ratio is measured to be σ ψ 2 S coh / σ J / ψ coh = 0.155 ± 0.014 ± 0.003, where the first uncertainty is statistical and the second is systematic. These results are compatible with theoretical predictions. [ABSTRACT FROM AUTHOR]

The simple analytic structure of meson scattering amplitudes in the large-Nc limit, combined with positivity of the spectral density, provides precise predictions on low-energy observables. Building upon previous studies, we explore the allowed regions of chiral Lagrangian parameters and meson couplings to pions. We reveal a structure of kinks at all orders in the chiral expansion and develop analytical tools to show that kinks always correspond to amplitudes with a single light pole. We build (scalar- and vector-less) deformations of the Lovelace-Shapiro and Coon UV-complete amplitudes, and show that they lie close to the boundaries. Moreover, constraints from crossing-symmetry imply that meson couplings to pions become smaller as their spin increases, providing an explanation for the success of Vector Meson Dominance and holographic QCD. We study how these conclusions depend on assumptions about the high-energy behavior of amplitudes. Finally, we emphasize the complementarity between our results and Lattice computations in the exploration of large-Nc QCD. [ABSTRACT FROM AUTHOR]

We compute the electromagnetic mass difference for the B-, D- and K-mesons using QCD sum rules with double dispersion relations. For the B- and D-mesons we also compute the linear quark mass correction, whereas for the K the standard soft theorems prove more powerful. The mass differences, which have not previously been computed via a double dispersion, are fully consistent with experiment, albeit with large uncertainties. [ABSTRACT FROM AUTHOR]

New results have been presented for the T20 component of the tensor analyzing power of the γd → ppπ– reaction measured in the photon energy range from 300 to 600 MeV. The data have been obtained from the statistical sample collected at the VEPP-3 accelerator in 2021. The T20 component has been separated using the asymmetry of the reaction yield, which is due to change in the sign of the tensor polarization of the deuterium target. The experimental data have been compared to the simulation within the spectator model including the interaction between particles in the final state. [ABSTRACT FROM AUTHOR]

Motivated by the recent developments in stability of hydrogen atom in a space with one finite extra-dimension,we consider that physical mesons are also stable in such a space and estimate their masses in a QCD inspired potential model. Our analysis suggests that a model of mesons with linear plus inverse distance potential in a space with one finite extra-dimension of size L ≪ 10 - 18 m is compatible with the present experimental data of heavy flavour mesons. [ABSTRACT FROM AUTHOR]