434 research outputs found

    Investigating the nature of the K0(700)^*_0(700) state with π±\pi^\pmKS0^0_{\rm S} correlations at the LHC

    No full text
    International audienceThe first measurements of femtoscopic correlations with the particle pair combinations π±\pi^\pmKS0^0_{\rm S} in pp collisions at s=13\sqrt{s}=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0(700)^*_0(700) particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a π±\pi^\pmKS0^0_{\rm S} pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0(700)^*_0(700). The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K0(700)^*_0(700) is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0(700)^*_0(700) resonance

    Investigating the nature of the K0(700)^*_0(700) state with π±\pi^\pmKS0^0_{\rm S} correlations at the LHC

    No full text
    International audienceThe first measurements of femtoscopic correlations with the particle pair combinations π±\pi^\pmKS0^0_{\rm S} in pp collisions at s=13\sqrt{s}=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0(700)^*_0(700) particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a π±\pi^\pmKS0^0_{\rm S} pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0(700)^*_0(700). The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K0(700)^*_0(700) is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0(700)^*_0(700) resonance

    Investigating the nature of the K0^*_0(700) state with π±\pi^\pmKS0^0_{\rm S} correlations at the LHC

    No full text
    The first measurements of femtoscopic correlations with the particle pair combinations π±\pi^\pmKS0^0_{\rm S} in pp collisions at s=13\sqrt{s}=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0(700)^*_0(700) particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a π±\pi^\pmKS0^0_{\rm S} pair. The extracted mass and Breit--Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0(700)^*_0(700). The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K0(700)^*_0(700) is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0(700)^*_0(700) resonance.The first measurements of femtoscopic correlations with the particle pair combinations π±\pi^\pmKS0^0_{\rm S} in pp collisions at s=13\sqrt{s}=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0(700)^*_0(700) particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a π±\pi^\pmKS0^0_{\rm S} pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0(700)^*_0(700). The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K0(700)^*_0(700) is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0(700)^*_0(700) resonance

    Investigating the nature of the K0(700)^*_0(700) state with π±\pi^\pmKS0^0_{\rm S} correlations at the LHC

    No full text
    International audienceThe first measurements of femtoscopic correlations with the particle pair combinations π±\pi^\pmKS0^0_{\rm S} in pp collisions at s=13\sqrt{s}=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0(700)^*_0(700) particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a π±\pi^\pmKS0^0_{\rm S} pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0(700)^*_0(700). The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K0(700)^*_0(700) is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0(700)^*_0(700) resonance

    Investigating the nature of the K0(700)^*_0(700) state with π±\pi^\pmKS0^0_{\rm S} correlations at the LHC

    No full text
    International audienceThe first measurements of femtoscopic correlations with the particle pair combinations π±\pi^\pmKS0^0_{\rm S} in pp collisions at s=13\sqrt{s}=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0(700)^*_0(700) particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a π±\pi^\pmKS0^0_{\rm S} pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0(700)^*_0(700). The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K0(700)^*_0(700) is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0(700)^*_0(700) resonance

    Investigating the nature of the K0(700)^*_0(700) state with π±\pi^\pmKS0^0_{\rm S} correlations at the LHC

    No full text
    International audienceThe first measurements of femtoscopic correlations with the particle pair combinations π±\pi^\pmKS0^0_{\rm S} in pp collisions at s=13\sqrt{s}=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0(700)^*_0(700) particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a π±\pi^\pmKS0^0_{\rm S} pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0(700)^*_0(700). The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K0(700)^*_0(700) is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0(700)^*_0(700) resonance

    Measurement of (anti)alpha production in central Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 5.02 TeV

    No full text
    International audienceIn this letter, measurements of (anti)alpha production in central (0-10%) Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon pair of sNN\sqrt{s_{\rm NN}} = 5.02 TeV are presented, including the first measurement of an antialpha transverse-momentum spectrum. Owing to its large mass, (anti)alpha production yields and transverse-momentum spectra are of particular interest because they provide a stringent test of particle production models. The averaged antialpha and alpha spectrum is included into a common blast-wave fit with lighter particles, indicating that the (anti)alpha also participates in the collective expansion of the medium created in the collision. A blast-wave fit including only protons, (anti)alpha, and other light nuclei results in a similar flow velocity as the fit that includes all particles. A similar flow velocity, but a significantly larger kinetic freeze-out temperature is obtained when only protons and light nuclei are included in the fit. The coalescence parameter B4B_4 is well described by calculations from a statistical hadronization model but significantly underestimated by calculations assuming nucleus formation via coalescence of nucleons. Similarly, the (anti)alpha-to-proton ratio is well described by the statistical hadronization model. On the other hand, coalescence calculations including approaches with different implementations of the (anti)alpha substructure tend to underestimate the data

    Studying the interaction between charm and light-flavor mesons

    No full text
    International audienceThe two-particle momentum correlation functions between charm mesons (D±\mathrm{D^{*\pm}} and D±\mathrm{D}^\pm) and charged light-flavor mesons (π±\pi^{\pm} and K±^{\pm}) in all charge-combinations are measured for the first time by the ALICE Collaboration in high-multiplicity proton-proton collisions at a center-of-mass energy of s=13\sqrt{s} =13 TeV. For DK\mathrm{DK} and DK\mathrm{D^*K} pairs, the experimental results are in agreement with theoretical predictions of the residual strong interaction based on quantum chromodynamics calculations on the lattice and chiral effective field theory. In the case of Dπ\mathrm{D}\pi and Dπ\mathrm{D^*}\pi pairs, tension between the calculations including strong interactions and the measurement is observed. For all particle pairs, the data can be adequately described by Coulomb interaction only, indicating a shallow interaction between charm and light-flavor mesons. Finally, the scattering lengths governing the residual strong interaction of the Dπ\mathrm{D}\pi and Dπ\mathrm{D^*}\pi systems are determined by fitting the experimental correlation functions with a model that employs a Gaussian potential. The extracted values are small and compatible with zero

    Common femtoscopic hadron-emission source in pp collisions at the LHC

    No full text
    International audienceThe femtoscopic study of pairs of identical pions is particularly suited to investigate the effective source function of particle emission, due to the resulting Bose-Einstein correlation signal. In small collision systems at the LHC, pp in particular, the majority of the pions are produced in resonance decays, which significantly affect the profile and size of the source. In this work, we explicitly model this effect in order to extract the primordial source in pp collisions at s=13\sqrt{s} = 13 TeV from charged π\pi-π\pi correlations measured by ALICE. We demonstrate that the assumption of a Gaussian primordial source is compatible with the data and that the effective source, resulting from modifications due to resonances, is approximately exponential, as found in previous measurements at the LHC. The universality of hadron emission in pp collisions is further investigated by applying the same methodology to characterize the primordial source of K-p pairs. The size of the primordial source is evaluated as a function of the transverse mass (mTm_{\rm T}) of the pairs, leading to the observation of a common scaling for both π\pi-π\pi and K-p, suggesting a collective effect. Further, the present results are compatible with the mTm_{\rm T} scaling of the p-p and pΛ-\Lambda primordial source measured by ALICE in high multiplicity pp collisions, providing compelling evidence for the presence of a common emission source for all hadrons in small collision systems at the LHC. This will allow the determination of the source function for any hadron--hadron pairs with high precision, granting access to the properties of the possible final-state interaction among pairs of less abundantly produced hadrons, such as strange or charmed particles

    Multiplicity dependence of charged-particle intra-jet properties in pp collisions at s\sqrt{s} = 13 TeV

    No full text
    International audienceThe first measurement of the multiplicity dependence of intra-jet properties of leading charged-particle jets in proton-proton (pp) collisions is reported. The mean charged-particle multiplicity and jet fragmentation distributions are measured in minimum-bias and high-multiplicity pp collisions at s\sqrt{s} = 13 TeV using the ALICE detector. Jets are reconstructed from charged particles produced in the midrapidity region (η<0.9|\eta| < 0.9) using the sequential recombination anti-kTk_{\rm T} algorithm with jet resolution parameters RR = 0.2, 0.3, and 0.4 for the transverse momentum (pTp_{\rm T}) interval 5-110 GeV/cc. High-multiplicity events are selected by the forward V0 scintillator detectors. The mean charged-particle multiplicity inside the leading jet cone rises monotonically with increasing jet pTp_{\rm T} in qualitative agreement with previous measurements at lower energies. The distributions of jet fragmentation functions zchz^{\rm ch} and ξch\xi^{\rm ch} are measured for different jet-pTp_{\rm T} intervals. Jet-pTp_{\rm T} independent fragmentation of leading jets is observed for wider jets except at high- and low-zchz^{\rm ch}. The observed "hump-backed plateau" structure in the ξch\xi^{\rm ch} distribution indicates suppression of low-pTp_{\rm T} particles. In high-multiplicity events, an enhancement of the fragmentation probability of low-zchz^{\rm ch} particles accompanied by a suppression of high-zchz^{\rm ch} particles is observed compared to minimum-bias events. This behavior becomes more prominent for low-pTp_{\rm T} jets with larger jet radius. The results are compared with predictions of QCD-inspired event generators, PYTHIA 8 with Monash 2013 tune and EPOS LHC. It is found that PYTHIA 8 qualitatively reproduces the jet modification in high-multiplicity events except at high jet pTp_{\rm T}. These measurements provide important constraints to models of jet fragmentation
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