Search

Charmonium production cross-section in proton–proton collisions is measured at the centre-of-mass energy s = 13 TeV using decays to p p ¯ final state. The study is performed using a data sample corresponding to an integrated luminosity of 2.2 fb - 1 collected in 2018 with the LHCb detector. The production cross-section of the η c meson is measured in a rapidity range of 2.0 < y < 4.0 and in a transverse momentum range of 5.0 < p T < 20.0 GeV / c , which is extended compared with previous LHCb analyses. The differential cross-section is measured in bins of p T and, for the first time, of y. Upper limits, at 90% and 95% confidence levels, on the η c (2 S) and h c (1 P) prompt production cross-sections are determined for the first time. [ABSTRACT FROM AUTHOR]

A search is reported for charge-parity CP violation in D 0 → K S 0 K S 0 decays, using data collected in proton–proton collisions at s = 13 Te V recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6 fb - 1 , which consists of about 10 billion events containing a pair of b hadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays D ∗ + → D 0 π + and D ∗ - → D ¯ 0 π - . The CP asymmetry in D 0 → K S 0 K S 0 is measured to be A CP (K S 0 K S 0) = (6.2 ± 3.0 ± 0.2 ± 0.8) % , where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the CP asymmetry in the D 0 → K S 0 π + π - decay. This is the first CP asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state. [ABSTRACT FROM AUTHOR]

The total charm-quark production cross section per unit of rapidity d σ (c c ¯) / d y , and the fragmentation fractions of charm quarks to different charm-hadron species f (c → h c) , are measured for the first time in p–Pb collisions at s NN = 5.02 Te V at midrapidity ( - 0.96 < y < 0.04 in the centre-of-mass frame) using data collected by ALICE at the CERN LHC. The results are obtained based on all the available measurements of prompt production of ground-state charm-hadron species: D 0 , D + , D s + , and J / ψ mesons, and Λ c + and Ξ c 0 baryons. The resulting cross section is d σ (c c ¯) / d y = 219.6 ± 6.3 (stat.) - 11.8 + 10.5 (syst.) - 2.9 + 8.3 (extr.) ± 5.4 (BR) ± 4.6 (lumi.) ± 19.5 (rapidity shape) + 15.0 (Ω c 0) mb , which is consistent with a binary scaling of pQCD calculations from pp collisions. The measured fragmentation fractions are compatible with those measured in pp collisions at s = 5.02 and 13 TeV, showing an increase in the relative production rates of charm baryons with respect to charm mesons in pp and p–Pb collisions compared with e + e - and e - p collisions. The p T -integrated nuclear modification factor of charm quarks, R pPb (c c ¯) = 0.91 ± 0.04 (stat.) - 0.09 + 0.08 (syst.) - 0.03 + 0.05 (extr.) ± 0.03 (lumi.) , is found to be consistent with unity and with theoretical predictions including nuclear modifications of the parton distribution functions. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated the two body decay of meson into and vector mesons which were collected with the LHCb detector for the first time, the branching fraction was measured to be . The fraction of longitudinal polarization in this decay was also measured to be . We have studied the decay within the framework of the factorization approach by using three different energy scales, the results obtained for branching fraction from helicity amplitude () and direct calculation (by omitting helicity ) at are and , respectively. By entering the nonfactorizable contributions the results for branching ratio become and , at the same scale. We have estimated the fraction of longitudinal polarization in decay mode, the result is obtained to be . The most precise determination for the branching fraction of decay has also been reported by the LHCb collaboration with the value of . Therefore, we have also calculated the branching ratio of this decay mode without and with entering the QCD corrections and obtained the numerical results as and . All numerical results are consistent with the experimental values. [ABSTRACT FROM AUTHOR]

This paper describes the method of neutrino tagging in neutrino experiments and the principles of its implementation. The neutrino tagging method consists in the kinematic reconstruction of the neutrino formation reaction—the decay —by measuring the parameters of the charged particles, parent meson and muon, using a tagging station. This allows recovering the energy, direction, and position of neutrino formation with a high accuracy. A description of the neutrino tagging method and the potential advantages of the resulting beam for short-base experiments are presented. The scheme of the neutrino tagging station is considered, and its operation is modeled. [ABSTRACT FROM AUTHOR]

Recently (2024), the NA61/SHINE collaboration has presented new experimental data on , , proton, and antiproton productions in central 40Ar + 45Sc collisions at the laboratory momenta Plab = 13–150 A GeV/c and has compared these data with predictions of popular theoretical models. It turned out that the models poorly describe the data in the entire energy range. In this work, it has been suggested for the first time that nucleons participating in non-diffractive collisions cannot diffractively dissociate in subsequent nucleon–nucleon collisions. This idea has been implemented in the Geant4 FTF model. Good description of the data, including the first NICA BM@N data on meson production in the collisions of 40Ar nuclei with various nuclei at an energy of 3.2 A GeV, has been achieved. [ABSTRACT FROM AUTHOR]

Charge density waves (CDWs) are pervasive orders in solids that usually enhance the effective mass (m*) and reduce the Fermi velocity ( v F ) of carriers. Here, we report on the inverse — a reduced m* and an enhanced v F correlated with the growth of the CDW order in CuTe with gapped, practically linearly dispersing bands — reminiscent of emergent CDW-gapped topological semimetals. Using momentum-dependent electron energy-loss spectroscopy (q-EELS), we simultaneously capture m* and v F of the CDW-related, practically linearly dispersing electrons by plasmon dispersions across the transition (335 K, TCDW), with m* of 0.28 m0 (m0, the electron rest mass) and v F of ~ 0.005c (c, the speed of light) at 300 K. With the growth of the CDW order-parameter strength toward 100 K, the electrons become lighter and move faster by ~ 20%. Thorough inspection below TCDW unveils the essential role of the increasing opening of the CDW gap. CuTe is a rich platform for the exploration of CDW/correlation physics with q-EELS established as a useful probe for this type of physics. Charge density waves usually cause electrons to become heavier and slow down. Here, the authors find the opposite is true in CuTe and study the phenomenon using advanced q-EELS. [ABSTRACT FROM AUTHOR]

Engineering Kondo lattice with tailored functionality is desirable for elucidating the heavy fermion physics. We realize the construction of an artificial Kondo lattice/superconductor heterojunction by growing monolayer VSe2 on bulk 2H-NbSe2 with molecular beam epitaxy. Spectroscopic imaging scanning tunneling microscopy measurements show the emergence of a new charge density wave (CDW) phase with 3 × 3 periodicity on the monolayer VSe2. Unexpectedly, a pronounced Kondo resonance appears around the Fermi level, and distributes uniformly over the entire film, evidencing the formation of Kondo lattice. Density functional theory calculations suggest the existence of magnetic interstitial V atoms in VSe2/NbSe2, which play a key role in forming the CDW phase along with the Kondo lattice observed in VSe2. The Kondo origin is verified from both the magnetic field and temperature dependences of the resonance peak, yielding a Kondo temperature of ~ 44 K. Moreover, a superconducting proximity gap opens on monolayer VSe2, whose shape deviates from the function of one-band BCS superconductor, but is reproduced by model calculations with heavy electrons participating the pairing condensate. Our work lays the experimental foundation for studying interactions between the heavy fermion liquids and the superconducting condensate. The authors observe a coherent Kondo lattice in a monolayer of VSe2 grown on a superconducting 2H-NbSe2 substrate. Superconductivity is established in the Kondo lattice through proximity effect from the substrate. [ABSTRACT FROM AUTHOR]

We study a long-overlooked CP violation observable, termed double-mixing CP violation, which arises from the interference between two neutral meson oscillating paths involved in a decay chain. The double-mixing CP violation is beneficial for the precise test of the Standard Model CKM mechanism, as it offers the potential to extract weak phases without pollution from strong dynamics. To provide a comprehensive understanding of the double-mixing CP violation, we perform phenomenological analyses on the cascade decays of the B d 0 and B s 0 mesons. Our results show that the double-mixing CP violation can be very significant in certain decay channels, such as B d 0 → J / ψ K → J / ψ (π + ℓ - ν ¯ ℓ) , where the total CP violation arises almost entirely from the double-mixing CP violation. In addition, we employ the decay process B d 0 → D 0 K → (K - π +) (π ℓ ν) to demonstrate that the involved strong and weak phases can be directly determined from the experimental data without any theoretical inputs. Specifically, the overall weak phase of this process is 2 β + γ , which is of significant importance for extracting the CKM phase angles. We also use B s 0 → ρ 0 K → ρ 0 (π - ℓ + ν ℓ) to illustrate and discuss the significant importance of K S 0 - K L 0 interference. [ABSTRACT FROM AUTHOR]

The study of neutrino oscillation at accelerators is limited by systematic uncertainties, in particular on the neutrino flux, cross section, and energy estimates. These systematic uncertainties could be eliminated by a novel experimental technique: neutrino tagging. This technique relies on a new type of neutrino beamline and its associated instrumentation which would enable the kinematic reconstruction of the neutrinos produced in and decays. This article presents a proof-of-concept study for such a tagged beamline, aiming to serve a long-baseline neutrino experiment exploiting a megaton scale natural water Cherenkov detector. After optimising the target and the beamline optics to first order, a complete Monte Carlo simulation of the beamline has been performed. The results show that the beamline provides a meson beam compatible with the operation of the spectrometer, and delivers a neutrino flux sufficient to collect neutrino samples with a size comparable with similar experiments and with other un-tagged long-baseline neutrino experimental proposals. [ABSTRACT FROM AUTHOR]

A new release of the Monte Carlo event generator Herwig (version 7.3) has been launched. This iteration encompasses several enhancements over its predecessor, version 7.2. Noteworthy upgrades include: the implementation of a process-independent electroweak angular-ordered parton shower integrated with QCD and QED radiation; a new recoil scheme for initial-state radiation improving the behaviour of the angular-ordered parton shower; the incorporation of the heavy quark effective theory to refine the hadronization and decay of excited heavy mesons and heavy baryons; a dynamic strategy to regulate the kinematic threshold of cluster splittings within the cluster hadronization model; several improvements to the structure of the cluster hadronization model allowing for refined models; the possibility to extract event-by-event hadronization corrections in a well-defined way; the possibility of using the string model, with a dedicated tune. Additionally, a new tuning of the parton shower and hadronization parameters has been executed. This article discusses the novel features introduced in version 7.3.0. [ABSTRACT FROM AUTHOR]

The optical scheme of the channel based on quadrupole lenses for neutrino beam formation at the accelerator complex U-70 is considered. A dual-magnet system with a field lens and full dispersion compensation is proposed to extract the required momentum interval of mesons. In this optical scheme, the decay part of the channel is rotated relative to the direction of the primary proton beam to the target. The main calculated characteristics of the neutrino beam at the far detector at a distance of 2595 km from the end of the decaying part of the channel as well as the parameters of the parent mesons at the beginning of the decaying part are discussed. [ABSTRACT FROM AUTHOR]

First results on the polarization of hyperons inclusively produced on 26.5-GeV/c and beams are presented. The measurements were carried out using the SPASCHARM setup at the U-70 accelerator facility (Protvino, Russia) on nuclear targets in 2021 and 2022. The polarization of an hyperon on the beam does not exceed several percent in most of the studied kinematic region. The data obtained on the -meson beam exhibit a significant positive polarization at large values of the Feynman variable xF and transverse momentum pT measured for the first time on nuclei. [ABSTRACT FROM AUTHOR]

We have developed the covariant approach for the partial wave analysis of the radiative decay of the vector meson into two pseudoscalar mesons based on the orbital momentum- intrinsic spin decomposition. This allowed us to include the data on the radiative decay into a large data base for analysis of the meson production reactions. The correspondence between partial wave amplitudes extracted in our approach and those extracted in the helicity basis is determined. [ABSTRACT FROM AUTHOR]

A partial-wave analysis (PWA) for the photoproduction of pseudoscalar mesons on a nucleon using truncation in total angular momentum j is discussed. A formalism is described that can be used for investigating discrete ambiguities. Considerable attention is devoted to the connection of this type of PWA with that based on the truncation in orbital angular momentum l. [ABSTRACT FROM AUTHOR]

The bioreduction characteristics and mechanisms of Cr(VI) onto Bacillus cereus RCr enhanced by ferric citrate were investigated. The optimum conditions were initial pH 9, temperature 40 °C, inoculation amount 4%, and glucose 3 g/L, respectively. The addition of 1.5 g/L ferric citrate increased the average reduction rate from 120.43 to 220.61 mg/(L∙h) compared with the control (without ferric citrate). The binding capacity of Cr(III) on the cell surface increased to 21%, in which the precipitates were mainly CrO(OH), Cr2O3, and FeCr2O4. Cell membrane was the main site of reduction, related important functional groups: − COOH, C-H, − NH2, C = C, and P-O. Fe(III) increased the yield of NADH and cytochrome c by approximately 48.51% and 68.63%, which significantly facilitated the electron generation and electron transfer, thus increasing the amount of electrons in the bioreduction of heavy metals by an average of 110%. Among the electrons obtained by Cr(VI), the proportion of indirect reduction mediated by Fe(III)/Fe(II) shuttle was 62% on average, whereas direct reduction mediated by reductase was 38%. These results may provide insights into the bioreduction process by bacteria enhanced by Fe(III) for detoxification of heavy metals with multiple valences, as an important step towards improving microbial remediation. [ABSTRACT FROM AUTHOR]

Nucleon–nucleon short range correlations (SRCs) in nuclei are important part of the nuclear structure and have been a subject of intensive studies in the last years. These objects represent temporary fluctuations in average nuclear matter density that occur when two or more nucleons separated by about 1 fm = 10–13 cm. Inspired by recent theoretical and experimental progress in understanding of SRC we reanalyzed our data on the production of high momentum and mesons emitted from nuclear targets irradiated by a proton beam. One of the basic properties of SRCs is the universality which means that they are equally involved in the creation of different hadrons on different nuclei, reflecting the properties of nuclear matter. So far, the property of universality has been observed in electron–nuclear collisions for the breakup of proton–neutron correlations, as well as in proton–nuclear collisions for the production of cumulative pions with high momenta. Both processes involve only light quarks. In this letter, we report the first observation of SRC universality in kaon production on nuclei in the kinematic region of high energy–momentum transfers thereby extending the investigation of the SRC universality to the sector of strange quarks. [ABSTRACT FROM AUTHOR]

The recently introduced topological heavy fermion model (THFM) provides a means for interpreting the low-energy electronic degrees of freedom of the magic angle twisted bilayer graphene as hybridization amidst highly dispersing topological conduction and weakly dispersing localized heavy fermions. In order to understand the Landau quantization of the ensuing electronic spectrum, a generalization of THFM to include the magnetic field B is desired, but currently missing. Here we provide a systematic derivation of the THFM in B and solve the resulting model to obtain the interacting Hofstadter spectra for single particle charged excitations. While naive minimal substitution within THFM fails to correctly account for the total number of magnetic subbands within the narrow band i.e., its total Chern number, our method—based on projecting the light and heavy fermions onto the irreducible representations of the magnetic translation group— reproduces the correct total Chern number. Analytical results presented here offer an intuitive understanding of the nature of the (strongly interacting) Hofstadter bands. The recently-developed topological heavy fermion model explains the low energy electrons of magic-angle twisted bilayer graphene as a hybridization between states localized at AA stacking sites and itinerant topological states, denoted by f and c electrons in analogy to heavy fermion systems. Here, the authors extend this model to a nonzero magnetic field, obtaining interacting Hofstadter spectra in the flatband limit by analytic methods. [ABSTRACT FROM AUTHOR]

Ratios ms/md and mu/md of the light quark masses have been determined from expressions for squared masses of pseudoscalar mesons and obtained with an accuracy of the second order in chiral symmetry breaking. The fit of the theoretical expressions for and to their phenomenological values leads to a functional relation between the ratios ms/md and mu/md, which is described by a third-order curve. The application of the lattice calculation result ms/mud = 27.23(10), where mud = (mu + md)/2, reported by the flavor lattice averaging group (FLAG) for the case of four quark flavors provides an additional constraint, which significantly reduces the error (~2%) for the ratio mu/md = 0.455(8). The absolute values of the quark masses have been then obtained. [ABSTRACT FROM AUTHOR]

The effects of external magnetic fields on monopoles, spectra of the overlap Dirac operator, instantons, and the mass of the eta-prime meson are examined by conducting lattice QCD simulations. The uniform external magnetic field is applied to gauge field configurations with flavor quarks. The bare quark masses are tuned in order to obtain the physical values of the pion mass and of the ratio. Standard configurations and configurations with an applied external magnetic field are generated in the color confinement and deconfinement phases. The intensity of the external magnetic field varies from to . To examine the influence of the external magnetic field on monopoles, we first calculate the monopole density, measure the lengths of the monopole loops, and compare them with the absolute value of the Polyakov loops. Next, using the generated configurations, we compute the eigenvalues and eigenvectors of the overlap Dirac operator, which preserves exact chiral symmetry. To investigate how external magnetic fields affect the spectra of the overlap Dirac operator, we compute spectral densities, compare fluctuations of the eigenvalues of the overlap Dirac operator with the predictions of random matrix theory, and estimate the number of instantons and anti-instantons from the topological charges. In addition, we analyze smearing effects on these observables and chiral symmetry breaking. Finally, we calculate the decay constant of the pseudoscalar meson, the chiral condensate, and the square mass of the eta-prime meson using the eigenvalues and eigenvectors. We then extrapolate the numerical results in the chiral limit and demonstrate the effects of external magnetic fields on the extrapolation results. This article presents preliminary results. [ABSTRACT FROM AUTHOR]

Partial widths and double- and single-differential distributions are calculated on the framework of the Standard Model for the four-lepton decays , where = and . The contribution of virtual-photon emission by a light quark and a heavy quark, the bremsstrahlung contribution from charged leptons in the final state, the weak-annihilation contribution, and the contribution of wide vector resonances are taken into account. The contribution of narrow and resonances is excluded. Virtual-photon emission by the light quark of a meson is described on the framework of the vector-meson-dominance model, within which only the contributions of the lightest vector mesons containing pairs are taken into account. For the meson, this is the resonance. For the meson, the contributions of the and resonances are taken into account. Two possibilities are considered in the present study. The first is that where the contributions of the narrow and mesons are excluded from the partial widths with respect to the corresponding decays. The second is that where the contributions of narrow resonances are taken into account in partial widths. The problem of the influence of the subtraction procedure on the partial widths with respect to the decays is studied individually. [ABSTRACT FROM AUTHOR]

The Spin Physics Detector (SPD) at the Nuclotron based Ion Collider fAcility (NICA) is designed to study nucleon spin structure in the three dimensions. At design energy, the leading mechanism of charm meson pair production in proton–proton collisions is the gluon fusion. At the SPD, charmed mesons can be detected via their hadronic decay channels. While these measurements are challenging due to orders of magnitude larger hadronic background, we demonstrate the capacity to obtain asymmetry measurements that can make an impact on the present understanding of gluon Transverse Momentum Dependent (TMD) distributions inside protons. [ABSTRACT FROM AUTHOR]

The recent results on charmonium production at BESIII are reviewed, including the observation of charmonium-like states in the processes of electron–positron annihilation into , , , and final states, as well as the study of the prompt inclusive production of the and mesons. [ABSTRACT FROM AUTHOR]

First results on -dependence measurements in inclusive meson production in interactions ( , Al, Cu, Sn, and W) are presented at GeV/c. The ratios of the differential cross sections of four of these nuclei to the differential cross section on aluminum were measured and the dependence of these cross sections on the atomic of the nucleus was studied. The measurements were carried out in the kinematic region of the Feynman variable and transverse momentum GeV/c. mesons were detected in the decay mode at the SPASCHARM experimental setup using negative charged beams at beamline 14 of the U-70 accelerator complex. [ABSTRACT FROM AUTHOR]

A novel observable, the double nuclear modification factor, is proposed to probe simultaneously the initial and final state effects in nucleus–nucleus collisions. An interesting competition between the combinatorial enhancement in the double parton scattering and the suppression due to parton energy loss can be observed in the production rate of two hard particles. In particular, the production of mesons in association with a W boson is not suppressed but is enhanced in the region of moderate transverse momenta, unlike the case of unassociated (inclusive) production. At the same time, in the region of high enough transverse momenta the nuclear modification factor for associated production converges to that of unassociated . [ABSTRACT FROM AUTHOR]

In heavy-ion collisions at intermediate energies, the production and propagation of Δ particles are crucial to understanding the nuclear equation of state and inferring the properties of nuclear matter at high densities. Based on the self-consistent relativistic Boltzmann-Uehling-Uhlenbeck (RBUU) transport theory, by introducing the isovector ρ meson exchange into the effective Lagrangian and adopting the density-dependent coupling constants, the detailed expressions for isospin-dependent in-medium N Δ → N Δ elastic cross sections σ N Δ ∗ have been calculated. The energy and density dependence of the isospin-related σ N Δ ∗ as well as the total contributions of σ , ω and ρ meson fields are analyzed. It is found that the total σ N Δ ∗ has a sensitive center-of-mass energy dependence at lower energies while exhibiting a slight increase as the center-of-mass energy increases. The isospin effect between different isospin-separated channels weakens as the energy and/or density increases. The isospin effect on the density- and energy-dependent in-medium N Δ elastic cross sections is dominantly caused by the delicate balance of the isovector ρ meson exchange. [ABSTRACT FROM AUTHOR]

The paper studies a strong coupling constant between π meson and octet baryon using the hard-wall AdS/QCD model, which considers SU(3)f symmetry-breaking effects. Briefly mentioned are profile functions for pseudoscalar meson and baryon fields. The obtained baryon coupling constants are in agreement with those obtained in theoretical calculations. [ABSTRACT FROM AUTHOR]

We present our first set of results for charm physics, using the mixed-action setup introduced in a companion paper [1]. Maximally twisted Wilson valence fermions are used on a sea of non-perturbatively O(a)-improved Wilson fermions, made up by CLS N f = 2 + 1 ensembles. Our charm-sector observables are free from O (a m c) discretisation effects, without need of tuning any improvement coefficient, and show continuum-limit scaling properties consistent with leading cutoff effects of O (a 2) . We consider a subset of CLS ensembles – including four values of the lattice spacing and pion masses down to 200 MeV – allowing to take the continuum limit and extrapolate to the physical pion mass. A number of techniques are incorporated in the analysis in order to estimate the systematic uncertainties of our results for the charm quark mass and the D (s) -meson decay constants. This first study of observables in the charm sector, where the emphasis has been on the control of the methodology, demonstrates the potential of our setup to achieve high-precision results. [ABSTRACT FROM AUTHOR]

The production of ψ(2S) mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of s NN = 8.16 TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb−1. The prompt and nonprompt ψ(2S) production cross-sections and the ratio of the ψ(2S) to J/ψ cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt ψ(2S) is observed to be more suppressed compared to pp collisions than the prompt J/ψ production, while the nonprompt productions have similar suppression factors. [ABSTRACT FROM AUTHOR]

In classical field theory, radiation does not reflect off of reflectionless kinks. In quantum field theory, radiation quanta, called mesons, can be reflected. We provide a general analytical formula for the leading order amplitude and probability for the elastic scattering of mesons off of reflectionless quantum kinks. In the case of the Sine-Gordon model we verify that, due to a cancellation of six contributing processes, our general formula yields an amplitude of zero, as is required by integrability. [ABSTRACT FROM AUTHOR]

The two-body leptonic decays of both light and heavy-charged mesons X l 2 ± are investigated in the first Born approximation in the presence of a monochromatic and circularly polarized laser field. As a result of using Volkov functions, the analytic study of these processes has brought a change in the parameters associated with each decay process. The decay width, lifetime, and branching ratio of each decay process are affected by increasing the classical parameter ξ of the meson. A comparison between the matter decay X l 2 + and that of the anti-matter X l 2 - in the presence of a circularly polarized laser wave, indicates that increasing laser field strength (increasing the classical parameter ξ ) can induce a slight dominance of matter over antimatter or vise versa. [ABSTRACT FROM AUTHOR]

This article elucidates the pivotal role of b-mesons and bottomonium states in exploring the existence and properties of hot QCD matter (commonly known as quark-gluon-plasma (QGP) produced within the crucible heavy-ion collision experiments). Owing to the complex and confounding nature of strong interaction force the direct detection of probing the hot QCD matter is not feasible. In light of this, investigating the dynamics of b-quarks and anti-quarks within the hot QCD medium emerges as an invaluable indirect probe. The impact of b-quarks and the mesons spans a spectrum of interesting domains regarding the physics of QCD at finite temperature, encompassing the QCD phase transition, color screening, quarkonia dissociation, heavy quark energy loss and collective flow, anisotropic aspects, and strongly coupled nature of hot QCD medium. These aspects underscore the indispensable nature of B-mesons in the quest to create and explore the complex nature of strong interaction force through the QGP/hot QCD matter. In this context, we mainly focus on works related to transport studies of b-mesons in hot QCD medium, lattice QCD, and effective field theory studies on bottomonium states, and finally, open quantum system frameworks to quarkonia to explore the properties of hot QCD medium in relativistic heavy-ion collision experiments. [ABSTRACT FROM AUTHOR]

We overview the current status and future perspectives of the QCD-based method of light-cone sum rules. The two main versions of these sum rules, using light-meson and B-meson distribution amplitudes are introduced and the most important applications of the method are discussed. We also outline open problems and future perspectives of this method. [ABSTRACT FROM AUTHOR]

Belle II collects data at the asymmetric electron-positron collider SuperKEKB, which operates with a centre-of-mass energy at, or close to, the mass of the Υ (4 S) resonance. The Υ (4 S) lies just above the kinematic threshold for B-meson-pair production, so Belle II collects a large sample of B + B - and B 0 B ¯ 0 pairs that are unaccompanied by other particles. The low-multiplicity final state and constrained kinematics allow many measurements with missing energy and neutral mesons in the final state that complement the B-physics measurements made by LHCb. In addition to B mesons, this center-of-mass energy has a similar cross section for electron-positron annihilation to c c ¯ and τ + τ - pairs, meaning Belle II also makes measurements of charm hadron and tau lepton properties. Finally, unique searches for hypothesized dark-sector particles with masses in the range 100 MeV–10 GeV are possible. This article reviews the current results from the Belle II experiment. [ABSTRACT FROM AUTHOR]

We discuss the main issues in dealing with heavy quarks on the lattice and shortly present the different approaches used. We discuss a selection of computations covering first the b-quark mass and the B (s) meson decay constants as the consolidated results (neglecting isospin breaking corrections). In the second part, we consider recent calculations of form factors for tree-level semileptonic decays with emphasis on the tensions between the results produced by different collaborations. We propose benchmark quantities and tests suited to investigate the origin of such tensions. Finally, we review computations of the bag parameters parameterising neutral meson mixing and provide an overview on a few recent developments in the field. [ABSTRACT FROM AUTHOR]

Two newly proposed Regge trajectory relations are employed to analyze the heavy-light systems. One of the relations is M = m 1 + m 2 + C ′ + β x x + c 0 x , (x = l , n r) . Another reads M = m 1 + C ′ + β x 2 (x + c 0 x) + 4 3 π β x m 2 3 / 2 (x + c 0 x) 1 / 4 . M is the bound state mass. m 1 and m 2 are the masses of the heavy constituent and the light constituent, respectively. l is the orbital angular momentum and n r is the radial quantum number. β x and c 0 x are fitted. m 1 , m 2 and C ′ are input parameters. These two formulas consider both of the masses of heavy constituent and light constituent. We find that the heavy-light diquarks, the heavy-light mesons, the heavy-light baryons and the heavy-light tetraquarks satisfy these two formulas. When applying the first formula, the heavy-light systems satisfy the universal description irrespective of both of the masses of the light constituents and the heavy constituent. When using the second relation, the heavy-light systems satisfy the universal description irrespective of the mass of the heavy constituent. The fitted slopes differ distinctively for the heavy-light mesons, baryons and tetraquarks, respectively. When employing the first relation, the average values of c f n r ( c fl ) are 1.026, 0.794 and 0.553 (1.026, 0.749 and 0.579) for the heavy-light mesons, the heavy-light baryons and the heavy-light tetraquarks, respectively. Upon application of the second relation, the mean values of c f n r ( c fl ) are 1.108, 0.896 and 0.647 (1.114, 0.855 and 0.676) for the heavy-light mesons, the heavy-light baryons and the heavy-light tetraquarks, respectively. Moreover, the fitted results show that the Regge trajectories for the heavy-light systems are concave downwards in the (M 2 , n r) and (M 2 , l) planes. [ABSTRACT FROM AUTHOR]

We study the inclusive production of hadrons with bottom flavor at the LHC and its luminosity upgrade. We describe the collinear fragmentation of singly b-flavored hadrons, B mesons and Λ b baryons, via the KKSS07 determination of fragmentation functions, while for charmed B mesons, B c (1 S 0) and B c (3 S 1) particles, we employ the novel ZCFW22 set, built on the basis of state-of-the-art nonrelativistic QCD inputs. We use the Jethad multimodular working environment to analyze rapidity and transverse-momentum distributions for observables sensitive to the associated emission of two hadrons or a hadron-plus-jet system. Our reference formalism is the NLL / NLO + hybrid collinear and high-energy factorization, where the standard collinear description is improved by the inclusions of energy logarithms resummed up to the next-to-leading approximation and beyond. We provide corroborating evidence that b-flavor emissions act as fair stabilizers of the high-energy resummation, thus serving as valuable tools for precision studies of high-energy QCD. As a bonus, we highlight that the predicted production-rate hierarchy between noncharmed b-hadrons and charmed B c (1 S 0) mesons is in line with recent LHCb estimates. This serves as simultaneous benchmark both for the hybrid factorization and for the single-parton fragmentation mechanism based on initial-scale inputs calculated via the nonrelativistic QCD effective theory. [ABSTRACT FROM AUTHOR]

The scalars f 0 closest to 1.5 GeV contain the mesons f 0 (1370) , f 0 (1500) and f 0 (1710) , and the latter two ones are usually viewed as the potential candidates for the scalar glueballs. In this work, by including the important contributions from the vertex corrections, we study the decays B 0 → J / ψ f 0 within the improved perturbative QCD approach and analyze the possible scalar glueball hunting. Together with the two mixing models, namely, f 0 (1500) (f 0 (1710)) being the primary scalar glueball in model I (II), and two classification scenarios, namely, f 0 being the q q ¯ excited (ground) states in scenario 1 (2), the branching fractions associated with their ratios for B 0 → J / ψ f 0 are evaluated comprehensively. The predictions with still large uncertainties in the considered two mixing models are roughly consistent with currently limited data, which indicates that both more rich data and more precise predictions are urgently demanded to figure out the scalar glueball clearly in the future. Moreover, several interesting ratios between the branching fractions of B 0 → J / ψ f 0 (→ π + π - / K + K -) and B 0 → J / ψ ρ 0 / ϕ (→ π + π - / K + K -) that could help us to understand the nature of scalar f 0 are defined and predicted theoretically. These ratios should be examined in future experiments. [ABSTRACT FROM AUTHOR]

Inclusive P-wave charmonia production in hadronic collisions at high energies is discussed in the framework of non-relativistic QCD and k T -factorization formalism. We present two consistent approaches to merge the usual leading order k T -factorization calculations with tree-level next-to-leading order off-shell amplitudes. Using these prescriptions, we extracted long-distance matrix elements for χ c mesons from a combined fit to available Tevatron and LHC data. In contrast to previous (leading order) calculations, our fits do not rule out the equalness of the color singlet wave functions of χ c 1 and χ c 2 states. The extracted values of long-distance matrix elements are employed to analyse the χ c polarization data reported recently by the CMS Collaboration. Our predictions are in a reasonably good agreement with the Tevatron and LHC measurements within the theoretical and experimental uncertainties. [ABSTRACT FROM AUTHOR]

This study focuses on the presence of (multi)fractal structures in hadronic matter through the momentum distributions of mesons produced in proton-proton collisions between 23 GeV and 63 GeV. The analysis demonstrates that the q-exponential behaviour of the particle momentum distributions is consistent with fractal characteristics, exhibiting fractal structures in confined hadronic matter with features similar to those observed in the deconfined quark-gluon plasma (QGP) regime. Furthermore, the systematic analysis of meson production in hadronic collisions at energies below 1 TeV suggests that specific fractal parameters are universal, independently of confinement or deconfinement, while others may be influenced by the quark content of the produced meson. These results pave the way for further research exploring the implications of fractal structures on various physical distributions. [ABSTRACT FROM AUTHOR]

The production cross-section of J/ψ pairs in proton-proton collisions at a centre-of-mass energy of s = 13 TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb−1 collected by the LHCb experiment. The measurement is performed with both J/ψ mesons in the transverse momentum range 0 < pT< 14 GeV/c and rapidity range 2.0 < y < 4.5. The cross-section of this process is measured to be 16.36 ± 0.28 (stat) ± 0.88 (syst) nb. The contributions from single-parton scattering and double-parton scattering are separated based on the dependence of the cross-section on the absolute rapidity difference ∆y between the two J/ψ mesons. The effective cross-section of double-parton scattering is measured to be σeff = 13.1 ± 1.8 (stat) ± 2.3 (syst) mb. The distribution of the azimuthal angle ϕCS of one of the J/ψ mesons in the Collins-Soper frame and the pT-spectrum of the J/ψ pairs are also measured for the study of the gluon transverse-momentum dependent distributions inside protons. The extracted values of ⟨cos 2ϕCS⟩ and ⟨cos 4ϕCS⟩ are consistent with zero, but the presence of azimuthal asymmetry at a few percent level is allowed. [ABSTRACT FROM AUTHOR]

Based on recent progress in the systematic analysis of C and CP violation in the light-meson sector, we calculate the C-odd transition amplitudes η → π0ℓ+ℓ− and η′ → ηℓ+ℓ−. Focusing on long-distance contributions driven by the lowest-lying hadronic intermediate states, we work out the correlations between these beyond-the-Standard-Model signals and the Dalitz-plot asymmetries in η → π0π+π− and η′ → ηπ+π−, using dispersion theory. [ABSTRACT FROM AUTHOR]

Recent developments in the Standard Model analysis of semileptonic charged-current processes involving light quarks have revealed ~ 3σ tensions in Cabibbo universality tests involving meson, neutron, and nuclear beta decays. In this paper, we explore beyond the Standard Model explanations of this so-called Cabibbo Angle Anomaly in the framework of the Standard Model Effective Field Theory (SMEFT), including not only low-energy charged current processes ('L'), but also electroweak precision observables ('EW') and Drell-Yan collider processes ('C') that probe the same underlying physics across a broad range of energy scales. The resulting 'CLEW' framework not only allows one to test explanations of the Cabibbo Angle Anomaly, but is set up to provide near model-independent analyses with minimal assumptions on the flavor structure of the SMEFT operators. Besides the global analysis, we consider a large number of simpler scenarios, each with a subset of SMEFT operators, and investigate how much they improve upon the Standard Model fit. We find that the most favored scenarios, as judged by the Akaike Information Criterion, are those that involve right-handed charged currents. Additional interactions, namely oblique operators, terms modifying the Fermi constant, and operators involving right-handed neutral currents, play a role if the CDF determination of the W mass is included in the analysis. [ABSTRACT FROM AUTHOR]

In this note we study the tensor and vector exchange contributions to the elastic reactions involving the pseudoscalars mesons π + π - , K + K - and D + D - . In the case of the tensor-exchange contributions we assume that an intermediate tensor f 2 (1270) is dynamically generated from the interaction of two virtual ρ mesons, with the use of a pole approximation. The calculation of the two-loop amplitude is facilitated since the triangle loops can be factorized and computed separately. The results show very small contributions coming from the tensor-exchange mechanisms when compared with those from the vector-exchange processes. We compare our results for π π and K K ¯ scattering with those obtained in other works where the f 2 (1270) is considered as an ordinary q q ¯ meson. Our picture provides a smaller contribution but of similar order of magnitude for pion scattering and stabilizes the results in the case of K K ¯ , allowing us to make estimates for D D ¯ scattering. [ABSTRACT FROM AUTHOR]

We calculate the spectrum and wave functions (WFs) of various states of bottomonium( b b ¯ ) mesons using a non-relativistic quark potential model (NRQPM). The calculated WFs are used to compute the radiative widths of various states of b b ¯ . The strong decays widths of bottomonium states are also calculated using 3 P 0 model by choosing simple harmonic oscillator wave functions (SHOWFs). The β of SHOWFs for various states of the mesons are measured by fitting the numerical wave functions. The radiative and strong decay widths are used to calculate the branching ratios of b b ¯ mesons. We also compare our calculated masses and widths with available experimental data. On basis of this comparison, it is suggested that Υ (10860) is the 5S state of b b ¯ mesons. [ABSTRACT FROM AUTHOR]

In this paper, we study the mass spectra of heavy quarkonia and heavy-light mesons in a curved space-time with conical geometry induced by a topological defect. The interactions between particles are modeled by an extended version of the Cornell potential, namely the singularized harmonic potential. To compute energy levels as well as the corresponding wave functions, the Hamiltonian operator is constructed within a torsion free space-time with a point-like global monopole. Then the full spectrum is obtained by solving the Schrödinger equation using the bi-confluent Heun equation. It is found that the energy spectra and wave functions of each meson differ from their flat Minkowski space-time counterparts. To check the efficiency of our model, we use the results of calculation to reproduce the mass spectra of heavy quarkonia such as b b ¯ , c c ¯ and some heavy-light mesons such as b ¯ c and c s ¯ . The mass spectra are calculated up to 4 S state at different values of the topological defect, then compared with experimental data and some relevant theoretical works. Decay constants are also computed for the selected mesons. The effect of the topological defect is also analyzed in details. It is observed that, for small values of the parameter α , our predictions approach the experimental data, especially when α = 0.39 . Whereas for α close to unity, the mass spectrum of the system gives values quite far from the experiment. [ABSTRACT FROM AUTHOR]

Based on recent progress in the systematic analysis of C and CP violation in the light-meson sector, we calculate the C-odd transition amplitudes η → π0ℓ+ℓ− and η′ → ηℓ+ℓ−. Focusing on long-distance contributions driven by the lowest-lying hadronic intermediate states, we work out the correlations between these beyond-the-Standard-Model signals and the Dalitz-plot asymmetries in η → π0π+π− and η′ → ηπ+π−, using dispersion theory. [ABSTRACT FROM AUTHOR]

A unified set of predictions for pion and kaon elastic electromagnetic and gravitational form factors is obtained using a symmetry-preserving truncation of each relevant quantum field equation. A key part of the study is a description of salient aspects of the dressed graviton + quark vertices. The calculations reveal that each meson's mass radius is smaller than its charge radius, matching available empirical inferences; and meson core pressures are commensurate with those in neutron stars. The analysis described herein paves the way for a direct calculation of nucleon gravitational form factors. [ABSTRACT FROM AUTHOR]

In this study, the form factors of B (s) to light D-wave tensor mesons with J PC = 2 - - ( ρ 2 , ω 2 , K 2 and ϕ 2 ) are calculated via the light cone sum rules (LCSR) in the framework of heavy quark effective eld theory (HQEFT). Firstly, the expressions of form factors in terms of the light cone distribution amplitudes (LCDAs) of tensor mesons are derived via the LCSR at the leading order of heavy quark expansion. Similar to the case of 2 + + tensor mesons, the penguin type form factors can be obtained directly from the corresponding semileptonic ones. Considering the light tensor meson LCDAs to twist-3 and quark mass corrections, we give the numerical results of form factors systematically. Based on the form factors given here, we investigate the branching ratios, longitudinal polarization fractions and forward-backward asymmetries of relevant charged current induced semileptonic decays. Our results may be tested by more precise experiments in the future. [ABSTRACT FROM AUTHOR]

A mechanism of the heavy quark dominance in the orbital excitation is proposed in this paper which is testified to be reasonable for singly and doubly heavy baryons. In the relativistic quark model, an analysis of the Hamiltonian figures out the mechanism that the excitation mode with lower energy levels is always associated with the heavy quark(s), and the splitting of the energy levels is suppressed by the heavy quark(s). So, the heavy quarks dominate the orbital excitation of singly and doubly heavy baryons. Furthermore, a physical understanding of this mechanism is given in a semi-classical way. Accordingly, the predicted mass spectra of singly and doubly heavy baryons confirm the rationality of this mechanism. In addition, an interesting consequence of this mechanism is that a heavy-light meson is more likely to be produced in the strong decay of the high-orbital excited states, which is supported by experiments. This mechanism is rooted in the breakdown of the mass symmetry. Therefore, it may be also valid for other multi-quark systems, such as the tetraquarks Qqqq and QQqq, or the pentaquarks Qqqqq and QQqqq. [ABSTRACT FROM AUTHOR]