Thermal properties of π and ρ meson Gao, Fei; Ding, Minghui
The European physical journal. C, Particles and fields,
12/2020, Letnik:
80, Številka:
12
Journal Article
Recenzirano
Odprti dostop
We computed the pole masses and decay constants of
π
and
ρ
meson at finite temperature in the framework of Dyson–Schwinger equations and Bethe–Salpeter equations approach. Below transition ...temperature, pion pole mass increases monotonously, while
ρ
meson seems to be temperature independent. Above transition temperature, pion mass approaches the free field limit of screening mass
∼
2
π
T
, whereas
ρ
meson is about twice as large as that limit. Pion and the longitudinal projection of
ρ
meson decay constants have similar behaviour as the order parameter of chiral symmetry, whereas the transverse projection of
ρ
meson decay constant rises monotonously as temperature increases. The inflection point of decay constant and the chiral susceptibility get the same phase transition temperature. Though there is no access to the thermal width of mesons within this scheme, it is discussed by analyzing the Gell-Mann-Oakes-Renner (GMOR) relation in medium. These thermal properties of hadron observables will help us understand the QCD phases at finite temperature and can be employed to improve the experimental data analysis and heavy ion collision simulations.
We apply a classical mathematical problem, the moment problem, with its related mathematical achievements, to the study of the parton distribution function (PDF) in hadron physics, and propose a ...strategy to sieve the moments of the PDF by exploiting its properties such as continuity, unimodality, and symmetry. Through an error-inclusive sifting process, we refine three sets of PDF moments from Lattice QCD. This refinement significantly reduces the errors, particularly for higher order moments, and locates the peak of PDF simultaneously. As our strategy is universally applicable to PDF moments from any method, we strongly advocate its integration into all PDF moment calculations.
A symmetry-preserving approach to the continuum bound-state problem in quantum field theory is used to calculate the masses, leptonic decay constants and light-front distribution amplitudes of ...empirically accessible heavy-light mesons. The inverse moment of the B-meson distribution is particularly important in treatments of exclusive B-decays using effective field theory and the factorisation formalism; and its value is therefore computed: λB(ζ=2GeV)=0.54(3)GeV. As an example and in anticipation of precision measurements at new-generation B-factories, the branching fraction for the rare B→γ(Eγ)ℓνℓ radiative decay is also calculated, retaining 1/mB2 and 1/Eγ2 corrections to the differential decay width, with the result ΓB→γℓνℓ/ΓB=0.47(15) on Eγ>1.5GeV.
The leading-twist parton distribution amplitudes (PDAs) of ground-state S01 and S13cc¯- and bb¯-quarkonia are calculated using a symmetry-preserving continuum treatment of the meson bound-state ...problem which unifies the properties of these heavy-quark systems with those of light-quark bound-states, including QCD's Goldstone modes. Analysing the evolution of S01 and S13 PDAs with current-quark mass, mˆq, increasing away from the chiral limit, it is found that in all cases there is a value of mˆq for which the PDA matches the asymptotic form appropriate to QCD's conformal limit and hence is insensitive to changes in renormalisation scale, ζ. This mass lies just above that associated with the s-quark. At current-quark masses associated with heavy-quarkonia, on the other hand, the PDAs are piecewise convex–concave–convex. They are much narrower than the asymptotic distribution on a large domain of ζ; but nonetheless deviate noticeably from φQQ¯(x)=δ(x−1/2), which is the result in the static-quark limit. There are also material differences between S01 and S13 PDAs, and between the PDAs for different vector-meson polarisations, which vanish slowly with increasing ζ. An analysis of moments of the root-mean-square relative-velocity, 〈v2m〉, in S01 and S13 systems reveals that 〈v4〉-contributions may be needed in order to obtain a reliable estimate of matrix elements using such an expansion, especially for processes involving heavy pseudoscalar quarkonia.
Electron-ion collider in China Anderle, Daniele P.; Bertone, Valerio; Cao, Xu ...
Frontiers of physics,
12/2021, Letnik:
16, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion ...collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a po- larization of 80%) and protons (with a polarization of 70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2-3)×10 33 cm −2*s −1. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.
The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.
This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.
Visible matter is characterised by a single mass scale; namely, the proton mass. The proton’s existence and structure are supposed to be described by quantum chromodynamics (QCD); yet, absent Higgs ...boson couplings, chromodynamics is scale-invariant. Thus, if the Standard Model is truly a part of the theory of Nature, then the proton mass is an emergent feature of QCD; and emergent hadron mass (EHM) must provide the basic link between theory and observation. Nonperturbative tools are necessary if such connections are to be made; and in this context, we sketch recent progress in the application of continuum Schwinger function methods to an array of related problems in hadron and particle physics. Special emphasis is given to the three pillars of EHM—namely, the running gluon mass, process-independent effective charge, and running quark mass; their role in stabilising QCD; and their measurable expressions in a diverse array of observables.
Pion and kaon structure at the electron-ion collider Aguilar, Arlene C.; Ahmed, Zafir; Aidala, Christine ...
The European physical journal. A, Hadrons and nuclei,
10/2019, Letnik:
55, Številka:
10
Journal Article
Recenzirano
Odprti dostop
.
Understanding the origin and dynamics of hadron structure and in turn that of atomic nuclei is a central goal of nuclear physics. This challenge entails the questions of how does the roughly 1GeV ...mass-scale that characterizes atomic nuclei appear; why does it have the observed value; and, enigmatically, why are the composite Nambu-Goldstone (NG) bosons in quantum chromodynamics (QCD) abnormally light in comparison? In this perspective, we provide an analysis of the mass budget of the pion and proton in QCD; discuss the special role of the kaon, which lies near the boundary between dominance of strong and Higgs mass-generation mechanisms; and explain the need for a coherent effort in QCD phenomenology and continuum calculations, in exa-scale computing as provided by lattice QCD, and in experiments to make progress in understanding the origins of hadron masses and the distribution of that mass within them. We compare the unique capabilities foreseen at the electron-ion collider (EIC) with those at the hadron-electron ring accelerator (HERA), the only previous electron-proton collider; and describe five key experimental measurements, enabled by the EIC and aimed at delivering fundamental insights that will generate concrete answers to the questions of how mass and structure arise in the pion and kaon, the Standard Model's NG modes, whose surprisingly low mass is critical to the evolution of our Universe.
We discover a correspondence between the free field and the interacting states. This correspondence is firstly given from the fact that the free propagator can be converted into a tower of ...propagators for massive states, when expanded with the Hermite function basis. The equivalence of propagators reveals that in this particular case the duality can naturally be regarded as the equivalence of one theory on the plane wave basis to the other on the Hermite function basis. More generally, the Hermite function basis provides an alternative quantization process with the creation/annihilation operators that correspond directly to the interacting fields. As an illustration, we apply this basis to the
3
+
1
dimensional Yang–Mills theory, where the three-dimensional space being reduced through the Hermite function basis, and an auxiliary parameter
ω
denotes for string tension. At large
ω
limit, with then considering only the lowest order Hermite function (Lowest Landau Level), the equivalent action becomes the Banks–Fischler–Shenker–Susskind (BFSS) matrix model. At small
ω
limit, the perturbative series summed over all orders of Hermite function gives a massive gluon propagator.
Stretchable hydrogel‐based strain sensors suffer from limited sensitivity, which urgently requires further breakthroughs for precise and stable human‐computer interaction. Here, an efficient ...microstructural engineering strategy is proposed to significantly enhance the sensitivity of hydrogel‐based strain sensors by sandwiching an emulsion‐polymerized polyacrylamide organohydrogel microsphere membrane between two Ecoflex films, which are accompanied by crack generation and propagation effects upon stretching. Consequently, the as‐developed strain sensor exhibits ultrahigh sensitivity (gauge factor (GF) of 1275), wide detection range (100% strain), low hysteresis, ultralow detection limit (0.05% strain), good fatigue resistance, and low fabrication cost. In addition, the sensor features good water, dehydration, and frost resistance, enabling real‐time strain monitoring in various complex conditions due to the encapsulation of Ecoflex film and the addition of glycerol and KCl. Through further structural manipulation, the device achieves superior response to tiny strains, with a GF value of 98.3 in the strain range of less than 1.5%. Owing to the high strain sensing performance, the sensor is able to detect various human activities from swallowing to finger bending even under water. On this basis, a wireless sensing system with apnea warning and single‐channel gesture recognition capabilities is successfully demonstrated, demonstrating its great promise as wearable electronics.
An ultrasensitive, stretchable, and environmental‐tolerant strain sensor based on crack mechanism with an Ecoflex‐microspheres‐Ecoflex sandwich structure is created successfully. It features ultra‐high sensitivity (gauge factor: 1275), wide detection range (0–100%), ultralow detection limit, wide operating temperature range, and good waterproofness. A wireless monitoring system is also developed, providing a more effective strategy to realize human–computer interfacing.
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