Geometric Scaling Analysis of Deep Inelastic Scattering Data Including Heavy Quarks

An analytic massive total cross section of photon proton scattering is derived, which has geometric scaling. A geometric scaling is used to perform a global analysis of the deep inelastic scattering data on inclusive structure function F2 measured in lepton-hadron scattering experiments at small values of Bjorken x. It is shown that the descriptions of the inclusive structure function F2 and longitudinal structure function FL are improved with the massive analytic structure function, which may imply the gluon saturation effect dominating the parton evolution process at HERA. The inclusion of the heavy quarks prevent the divergence of the lepton-hadron cross section, which plays a significant role in the description of the photoproduction region.

Analysis of the Diffractive Deep Inelastic Scattering Data with Running Coupling and Gluon Number Fluctuations

We study the effects of running coupling and gluon number fluctuations in the latest diffractive deep inelastic scattering data. It is found that the description of the data is improved once the running coupling and gluon number fluctuations are included with x2/d.o.f. = 0.867, x2/d.o.f. = 0.923 and x2/d.o.f. = 0.878 for three different groups of experimental data. The values of diffusive coefficient subtracted from the fit are smaller than the ones obtained by considering only the gluon number fluctuations in our previous studies. The smaller values of the diffusive coefficient are in agreement with the theoretical predictions, where the gluon number fluctuations are suppressed by the running coupling which leads to smaller values of the diffusive coefficient.

Analytic expression for the proton structure function in deep inelastic scattering

The analytic expression of proton in deep inelastic scattering is studied by using the color glass condensate model and the dipole picture. We get a better description of the HERA DIS data than the GBW model which was inspired by the Glauber model. We find that our model satisfies the unitarity limit and Froissart Bound which refers to an energy dependence of the total cross-section rising no more rapidly than ln^2 s.

Simulation of neutron-tagged deep inelastic scattering at EicC

Measuring the pionic structure function is of high interest, as it provides a new area for understanding the strong interaction among quarks and testing QCD predictions. To this end, we investigate the feasibility and expected impact of a possible experiment at EicC(Electron-ion collider in China). We show the simulation results on the statistical precision of an EicC measurement, based on the model of leading neutron tagged DIS process and the parton distribution functions of the pion from JAM18 global analysis. The simulation shows that at EicC, the kinematics cover the x π range from 0.01 to 1, and the Q2 range from 1 to 50 GeV2, within the acceptable statistical uncertainty. Assuming an integrated luminosity of 50 fb-1, in the low-Q2 region(< 10 GeV2), the Monte Carlo data show that the suggested measurement in the whole x π range reaches very high precision(< 3%). To perform such an experiment, only the addition of a far-forward neutron calorimeter is needed.

Hadron formation in semi-inclusive deep inelastic lepton-nucleus scattering

Hadron production in lepton-nucleus deep inelastic scattering is studied in a model including quark energy loss and nuclear absorption. The leading-order computations for hadron multiplicity ratios are presented and compared with the selected HERMES experimental data with the quark hadronization occurring inside the nucleus by means of the hadron formation time. It is shown that with increase of the energy fraction carried by the hadron, the nuclear suppression on hadron multiplicity ratio from nuclear absorption gets bigger. It is found that when hadronization occurs inside the nucleus, the nuclear absorption is the dominant mechanism causing a reduction of the hadron yield. The atomic mass dependence of hadron attenuation for quark hadronization starting inside the nucleus is confirmed theoretically and experimentally to be proportional to A1/3.

Atomic mass dependence of hadron production in semi-inclusive deep inelastic lepton-nucleus scattering

Hadron production in lepton-nucleus deep inelastic scattering is studied in a quark energy loss model. The leading-order computations for hadron multiplicity ratios are presented and compared with the selected HERMES pions production data with the quark hadronization occurring outside the nucleus by means of the hadron formation time. It is found that the obtained energy loss per unit length is 0.440±0.013 GeV/fm for an outgoing quark by the global fit. It is confirmed that the atomic mass number dependence of hadron attenuation is theoretically and experimentally in good agreement with the A2/3 power law for quark hadronization occurring outside the nucleus,

Many-Body Correlation Effects on the <i>x</i>_Bjorken-Dependence of Cross Section Ratios off Nuclei for 1 <<i>x</i>_Bjorken<2

Many-body correlations in nuclei determine the behavior of Deep-Inelastic-Scattering (DIS) and Quasi-Elastic Scattering (QES) cross section ratios off heavy over light nuclei especially for xBjorken > 1, obtained at Jefferson Lab. They can be described in terms of quark-cluster formation in nuclei due to wave-function overlapping, manifesting itself when the momentum transfer is high so that the partonic degrees of freedom are resolved. In clusters (correlated nucleons) the quark and gluon momentum distributions are softer than in single nucleons and extend to xBjorken > 1. The cluster formation probabilities are computed using a network-defining algorithm in which the initial nucleon density is either standard Woods-Saxon or is input from lower energy data while the critical radius for nucleon merging is an adjustable parameter. The exact choice of critical radius depends on the specific nucleus and it is anti-correlated to the rescaling of the xBjorken needed for bound nucleons. The calculations show that there is a strong dependence of the cross section ratios on the xBjorken in agreement with the data and that four-body correlations are needed to explain the experimental results even in the range 1 < xBjorken < 2. The dependence on the specific exponents of parton distributions in high-order clusters is weak.

Azimuthal Dependence of Intrinsic Top in Photon-Quark Scattering and Higgs Production in Boson-Gluon Fusion DIS

In this paper, we study the top content of nucleon by analyzing azimuthal asymmetries in lepton-nucleon deep inelastic scattering(DIS), also we search for the Higgs boson associated production channel, tˉt H, at the large hadron-electron collider(LHe C) caused by boson-gluon fusion(BGF) contribution. We use azimuthal asymmetries inγ*Q cross sections in terms of helicity contributions to semi-inclusive deep inelastic scattering to investigate numerical properties of the cos 2? distribution. We conclude that measuring azimuthal distributions caused by intrinsic heavy quark production can directly probe heavy quarks inside nucleon. Moreover, in order to estimate the probability of producing the Higgs boson, we suggest another approach in the framework of calculating tˉt cross section in boson-gluon fusion mechanism. Finally, we can confirm that this observed massive particle is referred to Higgs boson produced by fermion loop.

Highlights from the COMPASS experiment

The Compass experiment at CERN is studying the nucleon spin structure with a 160 GeV polarized muon beam and polarized targets as well as hadron structure with 190 GeV pion,kaon and proton beams.The paper gives an overview of the results for the helicity and transverse spin structure of the nucleon.A first result from the spectroscopy experiments,the observation of a resonance with exotic J P C = 1-＋ quantum numbers at 1660 MeV is also presented.The paper ends with an outlook to future measurements.

Tackling the kaon structure function at EicC

Measuring the kaon structure beyond proton and pion structures is a prominent topic in hadron physics,as it is one way to understand the nature of the Nambu-Goldstone boson of QCD and observe the interplay between the EHM and HB mechanisms for hadron mass generation.In this study,we present a simulation of the leading A baryon tagged deep inelastic scattering experiment at EicC(Electron-ion collider in China),which is engaged to unveil the internal structure of kaon via the Sullivan process.According to our simulation results,the suggested experiment will cover the kinematical domain of 0.05≤xK≤0.85 and Q^(2)up to 50 GeV^(2),with the acceptable statistical uncertainties.In the relatively low-Q^(2) region(<10 GeV^(2)),the Monte-Carlo simulation shows a good statistical precision(<5%)for the measurement of the kaon structure function F2K.In the high-Q^(2) region(up to 50 GeV^(2)),the statistical uncertainty of F_(2)^(K) is also acceptable(<10%)for the data at xK<0.8.To perform such an experiment at an electron-ion collider,a high-performance zero-degree calorimeter is suggested.The magnitude of the background process and the assumed detector capabilities are also discussed and illustrated in the paper.

Left-right asymmetry for meson production in SIDIS process

We analyze the left-right asymmetry in the semi-inclusive deep inelastic scattering （SIDIS） process using a method where no weighting function are used. Considering all flavor of quarks, we reanalyze the π±production and extend our calculation on the K± production. The predictions on HERMES, COMPASS and JLab kinematics with transversely polarized nucleon target are shown in this paper.

Gluon number fluctuations with heavy quarks at HERA

We study the effect of gluon number fluctuations （Pomeron loops） on the proton structure function at HERA. It is shown that the description of charm and bottom quarks and longitudinal structure functions are improved, with x^2/d.o.f=0.803 （fluctuations） as compared with x^2/d.o.f=0.908 （without fluctuations）, once the gluon number fluctuations are included. We find that in the gluon number fluctuation case the heavy quarks do not play an important role in the proton structure function as the saturation model. The successful description of the HERA data indicates that the gluon number fluctuation could be one of the key mechanisms to describe the proton structure function at HERA energies.

Search for charm-quark production via dimuons in neutrino telescopes

Dimuon events induced by charm-quark productions from neutrino deep inelastic scattering(DIS) processes have been studied in traditional DIS experiments for decades.The recent progress in neutrino telescopes makes it possible to search for such dimuon events at energies far beyond the laboratory scale.In this study,we construct a simulation framework to calculate yields and distributions of dimuon signals in an IceCube-like km3scale neutrino telescope.Owing to the experimental limitation in the resolution of double-track lateral distance,only dimuons produced outside the detector volume are considered.Detailed information about simulation results for a10-year exposure is presented.As an earlier paper [Physical Review D 105,093005(2022)] and ours report on a similar situation,we use that paper as a baseline to conduct comparisons.We then estimate the impacts of different calculation methods of muon energy losses.Finally,we study the experimental potential of dimuon searches under the hypothesis of single-muon background only.Our results based on a simplified double-track reconstruction indicate a moderate sensitivity,especially with the ORCA configuration.Further developments on both the reconstruction algorithm and possible detector designs are thus required and are under investigation.