Measurement of the Nucleon F 2 n / F 2 p Structure Function Ratio by the Jefferson Lab MARATHON Tritium/Helium-3 Deep Inelastic Scattering Experiment
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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Results for “Quark model”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Observation of Two New Excited Ξ b 0 States Decaying to Λ b 0 K − π +
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Observation of a State X ( 2600 ) in the π + π − η ′ System in the Process J / ψ → γ π + π − η ′
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Evidence for a Neutral Near-Threshold Structure in the K S 0 Recoil-Mass Spectra in e + e − → K S 0 D s + D * − and e + e − → K S 0 D s * + D −
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Observation of Three Charmoniumlike States with J P C = 1 − − in e + e − → D * 0 D * − π +
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
First Observation of a Doubly Charged Tetraquark and Its Neutral Partner
A combined amplitude analysis is performed for the decays $B^0$ → $\overline{D}$ 0 $D_s^+$$π^–$ and $B^+$ → $D^–$$D_s^+$$π^+$, which are related by isospin symmetry. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb –1 . Two new resonant states with masses of 2.908 ± 0.011 ± 0.020 GeV and widths of 0.136 ± 0.023 ± 0.013 GeV are observed, which decay to $D_s^+$$π^+$ and $D_s^+$$π^–$ respectively. The former state indicates the first observation of a doubly charged open-charm tetraquark state with minimal quark content [c$\overline{s}$u$\overline{d}$], and the latter state is a neutral tetraquark composed of [c$\overline{s}$$\overline{u}$d] quarks. Both states are found to have spin-parity of 0 + , and their resonant parameters are consistent with each other, which suggests that they belong to an isospin triplet.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Evidence of a $J/$$\psi$$K_S^0$ Structure in $B^0$ → $J/$$\psi$$\phi$$K_S^0$
An amplitude analysis of $B^0$ → $J/$$\psi$$\phi$$K_S^0$ decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 9 fb –1 , collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. Evidence with a significance of 4.0 standard deviations of a structure in the $J/$$\psi$$K_S^0$ system, named $T_{ψs1}^{θ}$(4000) 0 , is seen, with its mass and width measured to be 3991$_{–10 –17}^{+12 +9}$ MeV/c 2 and 105$_{–25 –23}^{+29 +17}$ MeV, respectively, where the first uncertainty is statistical and the second systematic. The $T_{ψs1}^{θ}$(4000) 0 state is likely to be the isospin partner of the $T_{ψs1}^{θ}$(4000) + state, previously observed in the $J/ψK^+$ system of the $B^+$→$J/ψ$$\phi$$K^+$ decay. When isospin symmetry for the charged and neutral $T_{ψs1}^{θ}$(4000) states is assumed, the signal significance increases to 5.4 standard deviations.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Observation of an Excess of Dicharmonium Events in the Four-Muon Final State with the ATLAS Detector
A search is made for potential $cc\bar{c}\bar{c}$ tetraquarks decaying into a pair of charmonium states in the four muon final state using proton-proton collision data at $\sqrt{s}$=13 TeV, corresponding to an integrated luminosity of 140 fb -1 recorded by the ATLAS experiment at LHC. Two decay channels, $J/ψ+J/ψ→4μ$ and $J/ψ+ψ(2S)→4μ$, are studied. Backgrounds are estimated based on a hybrid approach involving Monte Carlo simulations and data-driven methods. Statistically significant excesses with respect to backgrounds dominated by the single parton scattering are seen in the di-J/ψ channel consistent with a narrow resonance at 6.9 GeV and a broader structure at lower mass. A statistically significant excess is also seen in the $J/ψ+ψ$(2S) channel. The fitted masses and decay widths of the structures are reported.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Observation of New Charmonium or Charmoniumlike States in B + → D * ± D ∓ K + Decays
A study of resonant structures in B + → D * + D − K + and B + → D * − D + K + decays is performed, using proton-proton collision data at center-of-mass energies of s = 7 , 8, and 13 TeV recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb − 1 . A simultaneous amplitude fit is performed to the two channels with contributions from resonances decaying to D * − D + and D * + D − states linked by C parity. This procedure allows the C parities of resonances in the D * ± D ∓ mass spectra to be determined. Four charmonium or charmoniumlike states are observed decaying into D * ± D ∓ : η c ( 3945 ) , h c ( 4000 ) , χ c 1 ( 4010 ) , and h c ( 4300 ) , with quantum numbers J P C equal to 0 − + , 1 + − , 1 + + , and 1 + − , respectively. At least three of these states have not been observed previously. In addition, the existence of the T c ¯ s ¯ 0 * ( 2870 ) 0 and T c ¯ s ¯ 1 * ( 2900 ) 0 resonances in the D − K + mass spectrum, already observed in the B + → D + D − K + decay, is confirmed in a different production channel. © 2024 CERN, for the LHCb Collaboration 2024 CERN
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Quadrupole forces between quark and gluon subsystems inside higher-spin particles
We generalize the mechanical interpretation of the forces between quark and gluon subsystems, previously studied for the nucleon, to arbitrary higher-spin particles. For spin-0 and spin-1/2 particles, this force is characterized by the nonconserved $\overline{𝑐}$(𝑡) form factor. However, such an interpretation has not yet been established for higher-spin particles due to the intricate structure of the nonconserved energy-momentum tensor (EMT) form factors. By performing a multipole expansion, we identify the physically meaningful combinations of the nonconserved covariant EMT form factors and provide them with a clear mechanical interpretation.
Baryons↗
Phenomenology of soft hadron interactions and the relevant EAS data
The interpretation of the experimental data in superhigh energy cosmic rays requires the calculations using various models of elementary hadron interaction. One should prefer the models justified by accelerator data and giving definite predictions for superhigh energies. The model of quark-gluon pomeron strings (the QGPS models) satisfies this requirement.
Kalmykov, N. N.↗
Anomalies in cosmic rays: New particles versus charm?
For a long time two anomalies are observed in cosmic rays at energies E approx. = 100 TeV: (1) the generation of long-flying cascades in the hadron calorimeter (the so-called Tien-Shan effect) and; (2) the enhancement of direct muon yield as compared with the accelerator energy region. The aim is to discuss the possibility that both anomalies have common origins arising from production and decays of the same particles. the main conclusions are the following: (1) direct muons cannot be generated by any new particles with mass exceeding 10+20 GeV; and (2) if both effects are originated from the charmed hadrons, then the needed charm hadroproduction cross section is unexpectedly large as compared with the quark-gluon model predictions.
Balayan, G. L.↗
Gamma rays and energetic particles from primordial black holes
The standard model of quarks and leptons is used to discuss the signatures of black-hole evaporations. A firm bound on the primordial black hole abundance is obtained from MeV data. It is argued that the MeV bound can be improved by exploiting the new generation of TeV and PeV telescopes.
Halzen, F.↗
Partial Wave Analysis of the omega pi^- Final State Photoproduced at GlueX
The meson has traditionally been understood as the bound state of a quark and an anti-quark, but there is experimental evidence for exotic meson states, which have properties that cannot be produced by this quark-antiquark model. One candidate for such exotic systems is hybrid meson, predicted by lattice QCD, which includes gluonicexcitation in its wavefunction. One of the prominent decay modes of the lightest predicted exotic hybrid is expected to be b1pi. THis dissertation presernts an analysis of the gamma rho -> omega pi- Delta ++ channel produced at the GlueX experiment, in the mass range where the b1(1235) meson is prominent. An amplitude analysis is performed on the decay of the omega pi- system, in order to extract the resonance parameters of the b-1, as well as analyze the resonant and non-resonant background.
Schertz, Amy↗
High-Energy Collision of Quarks and Mesons in the Schwinger Model: From Tensor Networks to Circuit QED
With the aim of studying nonperturbative out-of-equilibrium dynamics of high-energy particle collisions on quantum simulators, we investigate the scattering dynamics of lattice quantum electrodynamics in 1 + 1 dimensions. Working in the bosonized formulation of the model and in the thermodynamic limit, we use uniform-matrix-product-state tensor networks to construct multiparticle wave-packet states, evolve them in time, and detect outgoing particles post collision. This facilitates the numerical simulation of scattering experiments in both confined and deconfined regimes of the model at different energies, giving rise to rich phenomenology, including inelastic production of quark and meson states, meson disintegration, and dynamical string formation and breaking. We obtain elastic and inelastic scattering cross sections, together with time-resolved momentum and position distributions of the outgoing particles. Furthermore, we propose an analog circuit-QED implementation of the scattering process that is native to the platform, requires minimal ingredients and approximations, and enables practical schemes for particle wave-packet preparation and evolution. Furthermore, this study highlights the role of classical and quantum simulation in enhancing our understanding of scattering processes in quantum field theories in real time.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Search for dark matter produced in association with a Standard Model Higgs boson decaying into b -quarks using the full Run 2 dataset from the ATLAS detector
The production of dark matter in association with Higgs bosons is predicted in several extensions of the Standard Model. An exploration of such scenarios is presented, considering final states with missing transverse momentum and b-tagged jets consistent with a Higgs boson. The analysis uses proton-proton collision data at a centre-of-mass energy of 13 TeV recorded by the ATLAS experiment at the LHC during Run 2, amounting to an integrated luminosity of 139 fb -1 . The analysis, when compared with previous searches, benefits from a larger dataset, but also has further improvements providing sensitivity to a wider spectrum of signal scenarios. These improvements include both an optimised event selection and advances in the object identification, such as the use of the likelihood-based significance of the missing transverse momentum and variable-radius track-jets. No significant deviation from Standard Model expectations is observed. Limits are set, at 95% confidence level, in two benchmark models with two Higgs doublets extended by either a heavy vector boson Z' or a pseudoscalar singlet a and which both provide a dark matter candidate χ. In the case of the two-Higgs-doublet model with an additional vector boson Z', the observed limits extend up to a Z' mass of 3 TeV for a mass of 100 GeV for the dark matter candidate. The two-Higgs-doublet model with a dark matter particle mass of 10 GeV and an additional pseudoscalar a is excluded for masses of the a up to 520 GeV and 240 GeV for tan β = 1 and tan β = 10 respectively. Limits on the visible cross-sections are set and range from to 0.05 fb to 3.26 fb, depending on the missing transverse momentum and b-quark jet multiplicity requirements.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the Neutron Electromagnetic Form Factor Ratio at High Momentum Transfer
The inner structure of the nucleon (proton and neutron) remains a topic of great interest in nuclear and particle physics, after many decades of study. For example, understanding the quark-gluon dynamics inside the nucleon would shed light on how 99% of the nucleon mass is created. The neutron electromagnetic form factors, Gn E and Gn M , give important insights into the neutron structure. The Super BigBite Spectrometer (SBS) program at Jefferson Lab (JLab) seeks to extend the form factor measurements for both the proton and the neutron. The neutron electric form actor, Gn E , has been historically difficult to measure due to the short lifetime of the free neutron and the small value of Gn E . The GEn-II experiment is part of the SBS program and seeks to measure Gn E , significantly increasing the high momentum transfer coverage. A newly designed polarized 3He target increased the figure of merit by three times compared to previous measurements. The analysis of this data is especially challenging due to the unprecedented high-rate environment caused by the open nature of the spectrometer with a direct line of sight to the target. This required developing new Gas Electron Multiplier (GEM) particle trackers which can cover large areas demanded by this setup and handle particle rates up to 500 kHz/cm2. Rates this high over a large area is unprecedented in particle tracking systems and came with a number of challenges. Data taken in the SBS program was critical to understanding hardware and software solutions that improved the track reconstruction efficiency to be >97% with a position resolution of 70 ?m. In previous experiments the proton electromagnetic form factors, Gp E and Gp M were measured up to Q2 = 8.5 GeV2 and Q2 = 30 GeV2, respectively, while Gn E has only been measured up to Q2 = 3.4 GeV2. The GEn-II experiment has measured the neutron form factor ratio, Gn E/Gn M, at Q2 values of 2.90, 6.50, and 9.47 GeV2 by scattering a polarized electron beam with a polarized 3He target, used here as an effective polarized neutron target, and measuring the double spin asymmetry of the cross section. Previous Gn E measurements do not extend above Q2 = 3.4 GeV2, and therefore this analysis has extended the world data by almost three times. The background correction is especially difficult at the higher Q2 settings leading to large systematic errors. As very exploratory results from this early analysis of the data, we find for Q2 = 2.90 GeV2, Gn E = 0.0157 ±stat 0.0016 ±sys 0.0011, for Q2 = 6.50 GeV2, Gn E = 0.0067 ±stat 0.0019 ±sys 0.0005, and for Q2 = 9.46 GeV2, Gn E = 0.0046 ±stat 0.0023 ±sys 0.0005. These results are compared to predictions from the Dyson-Schwinger Equations (DSE) model and a Relativistic Constituent Quark Model (RCQM).
Jeffas, Sean↗
Hidden-strangeness tetraquarks in the dynamical diquark model
The dynamical diquark model describes multiquark exotic hadrons in terms of diquark components nucleated by heavy quarks and successfully explains multiple features of hidden-charm and hidden-bottom exotics. Here, we apply the model to the marginally heavy case of hidden-strange states to probe whether mesons near 2 GeV with peculiar properties, such as 𝜙(2170), 𝑓 2 (2340), and 𝑋(2370), are possible tetraquark candidates. We calculate spin-multiplet average masses using potentials obtained through lattice simulations and quark models, and we also describe the detailed spectra of the expected multiplets as a diagnostic to discern the nature of future hadrons likely to be discovered in this mass region by experiments at facilities such as BESIII, JLab, and the EIC.
Bound states↗