F2 Structure Research Articles

Superfast quarks in deuterium

An extension to our previous study on nuclear parton distribution functions (nPDFs) [Kim and Miller, ] using light-front holographic quantum chromodynamics (LFHQCD) [Brodsky, de Teramond, Dosch, and Erlich, ] is presented. We apply the effects of nucleon motion inside the nucleus (Fermi motion/smearing) to deuterium, extending our deuterium nPDFs to the , x>1, region [Frankfurt and Strikman, ] where we estimate our results to be reasonable up to x≈1.7. We utilize four different deuteron wave functions (AV18, NijmI, NijmII, Nijm93). We find that our model, with no additional new parameters, shows very good agreement with deuterium EMC ratio data obtained from the BONuS experiment [Fenker , ; Baillie (CLAS Collaboration), ; ; Tkachenko (CLAS Collaboration), ; ; Griffioen , ]. Looking beyond conventional nuclear physics, and in anticipation of 12 GeV experiments at Jefferson Lab, we use a LFHQCD ansatz to predict the contributions of an exotic six-quark state to the deuteron F2 structure function, F2D, in the superfast region. We find that the effects of using other potentials are about the same magnitude as six-quark effects—both have small effects in x<1, but have significant contributions at x>1. Published by the American Physical Society 2024

Inferring the initial condition for the Balitsky-Kovchegov equation

We apply Bayesian inference to determine the posterior likelihood distribution for the parameters describing the initial condition of the small-x Balitsky-Kovchegov evolution equation at leading logarithmic accuracy. The HERA structure function data is found to constrain most of the model parameters well. In particular, we find that the HERA data prefers an anomalous dimension γ≈1 unlike in previous fits where γ>1 which led to, e.g., the unintegrated gluon distribution and the quark-target cross sections not being positive definite. The determined posterior distribution can be used to propagate the uncertainties in the nonperturbative initial condition when calculating any other observable in the color glass condensate framework. We demonstrate this explicitly for the inclusive quark production cross section in proton-proton collisions and by calculating predictions for the nuclear modification factor for the F2 structure function in the EIC and LHeC/FCC-he kinematics. Published by the American Physical Society 2024

Solutions to the Balitsky-Kovchegov equation including the dipole orientation

Solutions of the target-rapidity Balitsky-Kovchegov (BK) equation are studied considering, for the first time, the complete impact-parameter dependence, including the orientation of the dipole with respect to the impact-parameter vector. In our previous work [1] it has been demonstrated that the spurious Coulomb tails could be tamed using the collinearly-improved kernel and an appropriate initial condition in the projectile-rapidity BK equation. Introducing a different interpretation of the evolution variable, the target-rapidity formulation of the BK equation brings non-locality in rapidity and a kernel modification, removing the term that previously helped to suppress the Coulomb tails. To address this newly emerged non-locality, three different prescriptions are explored here to take into account the rapidities preceding the initial condition. Two of these approaches induce mild Coulomb tails, while the other is free from this effect within the studied rapidity range. The range is chosen to correspond to that of interest for existing and future experiments. To demonstrate that this set up can be used for phenomenological studies, the obtained solutions are used to compute the F2 structure function of the proton and the diffractive photo- and electro-production of J/ψ off protons. The predictions agree well with HERA data, confirming that the target-rapidity Balitsky-Kovchegov equation with the full impact-parameter dependence is a viable tool to study the small Bjorken-x limit of perturbative QCD at current facilities like RHIC and LHC as well as in future colliders like the EIC.

Photophysical properties of several multi-branched oligomers: An ultrafast excited state dynamics and quantum chemical calculation study

Multi-branched oligomers F1, F2 and F3 were investigated by spectroscopic experiments as well as quantum chemical calculations to elucidate the structure–property relationships and intramolecular charge transfer (ICT) characteristics of typical nonlinear optical materials. A better ICT property of F2 is obtained by replacing terminal electron donors with stronger electron-donating ability. The degree of ICT is effectively increased, which can be clearly seen from the frontier molecular orbitals contribution of central anthracene between HOMO and LUMO. The central group plays a major role in the direction as well as effective path of ICT process. In the X-shaped oligomers with anthracene as central group, ICT process takes place from terminal groups of [Formula: see text] position branches, to the central anthracene group. However, the electron distribution as well as the ICT of tri-branched oligomer F3 with triazine as central group is not symmetric. ICT process of F3 takes place from terminal triphenylamine groups to the central triazine and two fluorene groups at [Formula: see text] position branches. Y-shaped oligomer F3 has a longer lifetime of ICT state as well as a higher fluorescence quantum yield, which is consistent with the results of time-resolved fluorescence spectroscopy. Z-scan results show that the TPA cross-section value of F3 is 10.6 and 2.9 times higher than that of X-shaped F1 and F2. The dynamics curves of transient absorption spectroscopy also indicate that oligomer F3 structure has relatively stronger ICT properties. To verify the substituent effect, two linear molecules F4 and F5 were also calculated. The quantum chemical calculations result shows that the branches at positions 4 and 11 of the central anthracene group have little effect on the electron cloud distribution, and there are indeed significant differences in the contributions of branches at different positions. Our results may provide some reference for molecular design.

Effect of fluorine substitution on the photobiological and electronic properties of resveratrol crystal structure: A first- principles study

The electrical and optical properties of pure resveratrol (RS) and RS derivatives from substituted fluorine atom at hydrogen sites (fluorine is bonded to an oxygen or a carbon atom) are investigated by first-principles calculations. It is shown that RS is a semiconductor with an indirect bandgap of 2.47 eV. The substitution of hydrogen atoms by fluorine atoms that is bonded to oxygen atom changes the bandgap value and affect significantly on optical properties of RS. For other derivatives, the hydrogen substitution by fluorine does not change the bandgap value sensibility. The nature of band gap change from indirect to direct at F3 structure. Optical spectra of F3 to F8 derivatives are very similar to RS. Birefringenceis observed in all RS derivatives. The results show that fluorine atoms play key role in photo biological applications of RS derivatives.

Hierarchical Modulation of Optical Anisotropy Driven by Metal Cation Polyhedra in Fluorooxoborates MII B4 O6 F2 (MII =Be, Mg, Pb, Zn, Cd).

The enhancement mechanism of birefringence is very important to modulate optical anisotropy and materials design. Herein, the different cations extending from alkaline-earth to alkaline-earth, d10 electron configuration, and 6s2 lone pair cations are highlighted to explore the influence on the birefringence. A flexible fluorooxoborate framework from AEB4 O6 F2 (AE=Ca, Sr) is adopted for UV/deep-UV birefringent structures, namely, MII B4 O6 F2 (MII =Be, Mg, Pb, Zn, Cd). The maximal enhancement on birefringence can reach 46.6 % with the cation substitution from Ca, Sr to Be, Mg (route-I), Pb (route-II), and Zn, Cd (route-III). The influence of the cation size, the stereochemically active lone pair, and the binding capability of metal cation polyhedra is investigated for the hierarchical improvement on birefringence. Significantly, the BeB4 O6 F2 structure features the shortest UV cutoff edge 146 nm among the available anhydrous beryllium borates with birefringence over 0.1 at 1064 nm, and the PbB4 O6 F2 structure has the shortest UV cutoff edge 194 nm within the reported anhydrous lead borates that hold birefringence larger than 0.1 at 1064 nm. This work sheds light on how metal cation polyhedra modulate birefringence, which suggests a credible design strategy to obtain desirable birefringent structures by cation control.

Polymorphism, Isomorphism, and Morphotropy in Trifluorides of Rare-Earth Elements (R) and RF3–R'F3 Systems

The relationship between the polymorphism, isomorphism, and morphotropy has been traced for the homologous series of 16 trifluorides of rare-earth elements (REEs) (without ScF3) and R1 – xR $$_{x}^{'}$$ F3 phases (R is an REE) based on the T–x diagrams of RF3–R'F3 systems. The polymorphism is determined by the REE atomic numbers Z and Т values, which change the cation/anion radius ratio r+/r–. Four structural RF3 subgroups are selected according to the polymorphism and types of LaF3, β-YF3, and α-YF3 (α-UO3) structures: A (R = La–Nd), B (R = Pm–Gd), C (R = Tb–Ho), and D (R = Er–Lu, Y). Combinations of RF3 form 10 types of RF3–R’F3 systems. Isomorphism (both perfect and limited) manifests itself in the homogeneity range of R1 – xR $$_{x}^{'}$$ F3 phases. It affects the R1 – xR $$_{x}^{'}$$ F3 structure via the r+/r– ratio by preparing (jointly with Т) their morphotropic transformations (MTs). The morphotropy of R1 – xR $$_{x}^{'}$$ F3 is regulated by the parameters Т and х via the ratio r+/r– and is implemented by means of phase reactions of melt with R1 – xR $$_{x}^{'}$$ F3 and R1 – yR $$_{y}^{'}$$ F3 of different structures at peritectic (MT-I) and (or) eutectic (MT-II) temperatures. Morphotropic transformations of R1 – xR $$_{x}^{'}$$ F3 structures occur at the boundary of GdF3–TbF3 (Z = 64.43–64.51; МT-I; 1186 ± 10°С) and HoF3–ErF3 (Z = 67.67–67.36; МT-II; 1120 ± 10°С). A definition of true morphotropy for systems in T–x coordinates is given.

Novel polysaccharide from Chaenomeles speciosa seeds: Structural characterization, α-amylase and α-glucosidase inhibitory activity evaluation

Purification and structural characterization of a novel polysaccharide fraction from Chaenomeles speciosa seeds were investigated. After hot water extraction and ethanol precipitation, the crude polysaccharide was sequentially purified with Cellulose DEAE-52 and gel-filtration chromatography, and a highly purified polysaccharide fraction (F3) was obtained. The structure of F3 was characterized by high-performance gel permeation chromatography (HPGPC), high performance liquid chromatography (HPLC), ultraviolet-visible (UV), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectrum, together with methylation, scanning electron microscopy (SEM), atomic force microscope (AFM), and Congo-red test analysis. The results indicated that F3 was a homogeneous polysaccharide fraction with a molecular weight of 8.65 × 106 Da, and it was composed of Rha, GlcA, Gal, and Ara in a molar ratio of 6.34:5.73:47.14:40.13. The backbone of F3 was consisted of →3,6)-Galp-(1→, and the side chains of F3 were composed of Araf-(1→, →4)-GlcpA-(1→, →4)-Galp-(1→ and →3)-Rhap-(1→. The hypoglycemic assays demonstrated F3 had good α-amylase and α-glucosidase inhibition activities, and their IC50 values were 6.24 mg/mL and 4.59 mg/mL respectively. Thus, the polysaccharide from Chaenomeles speciose could be applied as a potential natural source in retarding postprandial hyperglycemia effects.

Small-x analysis on the effect of gluon recombinations inside hadrons in light of the GLR-MQ-ZRS equation

We present a study of the contribution of antishadowing effects on the gluon distribution functions G(x,Q2) in light of the Gribov-Levin-Ryskin-Mueller-Qiu, Zhu-Ruan-Shen (GLR-MQ-ZRS) nonlinear equation at small-x, where x is the momentum fraction or Bjorken variable and Q2 is the four momentum transfer squared or photon virtuality. In this work, we have solved the GLR-MQ-ZRS nonlinear equation using Regge like behaviour of gluons in the kinematic range of 10−2≤x≤10−6 and 5GeV2≤Q2≤100GeV2 respectively. We have obtained the solution of G(x,Q2) by considering two particular cases: (a) αs fixed; and (b) the leading order QCD dependency of αs on Q2. A comparative analysis is also performed where we compare the gluon distribution function due to inclusion of the antishadowing effect with that of the gluon distribution without including the antishadowing effect. Our obtained results of G(x,Q2) are compared with NNPDF3.0, CT14 and PDF4LHC. We also compare our results with the result obtained from the IMParton C++ package. Using the solutions of G(x,Q2), we have also predicted x and Q2 evolution of the logarithmic derivative of proton's F2 structure function i.e. dF2(x,Q2)/dln⁡Q2. We incorporated both the leading order(LO) and next-to-leading order (NLO) QCD contributions of the gluon-quark splitting kernels, in dF2(x,Q2)/dln⁡Q2. Our result of dF2(x,Q2)/dln⁡Q2 agrees reasonably well with the experimental data recorded by HERA's H1 detector.

Structural bases for F plasmid conjugation and F pilus biogenesis in Escherichia coli

Bacterial conjugation systems are members of the large type IV secretion system (T4SS) superfamily. Conjugative transfer of F plasmids residing in the Enterobacteriaceae was first reported in the 1940s, yet the architecture of F plasmid-encoded transfer channel and its physical relationship with the F pilus remain unknown. We visualized F-encoded structures in the native bacterial cell envelope by in situ cryoelectron tomography (CryoET). Remarkably, F plasmids encode four distinct structures, not just the translocation channel or channel-pilus complex predicted by prevailing models. The F1 structure is composed of distinct outer and inner membrane complexes and a connecting cylinder that together house the envelope-spanning translocation channel. The F2 structure is essentially the F1 complex with the F pilus attached at the outer membrane (OM). Remarkably, the F3 structure consists of the F pilus attached to a thin, cell envelope-spanning stalk, whereas the F4 structure consists of the pilus docked to the OM without an associated periplasmic density. The traffic ATPase TraC is configured as a hexamer of dimers at the cytoplasmic faces of the F1 and F2 structures, where it respectively regulates substrate transfer and F pilus biogenesis. Together, our findings present architectural renderings of the DNA conjugation or "mating" channel, the channel-pilus connection, and unprecedented pilus basal structures. These structural snapshots support a model for biogenesis of the F transfer system and allow for detailed comparisons with other structurally characterized T4SSs.

High-precision numerical estimates of the Mellin-Barnes integrals for the structure functions based on the stationary phase contour

We present a recipe for constructing the effcient contour which allows one to calculate with high accuracy the Mellin-Barnes integrals, in particular, for the F3 structure function written in terms of its Mellin moments. We have demonstrated that the contour of the stationary phase arising for the F3 structure function tends to the finite limit as Re(z) → –∞. We show that the Q2 evolution of the structure function can be represented as an integral over the contour of the stationary phase within the framework of the Picard-Lefschetz theory. The universality of the asymptotic contour of the stationary phase defined at some fixed value of the momentum transfer square $Q_{0}^{2}$ for calculations with any Q2 is shown.

A sulfated galactofucan from the brown alga Hormophysa cuneiformis (Fucales, Sargassaceae)

The brown alga Hormophysa cuneiformis collected from the coastal waters of Vietnam was used to isolate a mixture of sulfated polysaccharides FHC, which was fractionated further by anion-exchange chromatography on DEAE-Sephacel. The main fraction F3 eluted with 1.5 M NaCl contained essentially l-fucose, d-galactose and sulfate and has very complex NMR spectra. Desulfation to obtain F3deS followed by Smith degradation to obtain F3deS-Sm was used to simplify the structure of F3, and all these preparations were characterized by methylation analysis and NMR spectra. A linear (1 → 3)-linked backbone built up of α-l-fucopyranose residues was identified as the main structural motif of molecules. Some fucose residues attached to position 4 of its 3-linked neighbor were found as branches. Galactose residues having both α- and β-configurations were found mostly at the periphery of molecules. They are present as (1 → 6)-linked disaccharide of two β-d-Galp attached to position 4 of the backbone or as single α-d-Galp attached to the same position. Sulfate groups in F3 may probably occupy any positions of the molecule. F3 acts as anticoagulant and is about half as active as the standard low-molecular mass heparin (enoxaparin). FHC was practically inactive in cytotoxicity test against six human cancer cell lines.

Self-dual 6d 2-form fields coupled to non-abelian gauge field: quantum corrections

We study a 6d model of a set of self-dual 2-form B-fields interacting with a non-abelian vector A-field which is restricted to a 5d subspace. One motivation is that if the gauge vector could be expressed in terms of the B-field or integrated out, this model could lead to an interacting theory of B-fields only. Treating the 5d gauge vector as a background field, we compute the divergent part of the corresponding one-loop effective action which has the (DF)2 + F3 structure and compare it with similar contributions from other 6d fields. We also discuss a 4d analog of the non-abelian self-dual model, which turns out to be UV finite.

Genetic Diversity and Population Structure of F3:6 Nebraska Winter Wheat Genotypes Using Genotyping-By-Sequencing.

The availability of information on the genetic diversity and population structure in wheat (Triticum aestivum L.) breeding lines will help wheat breeders to better use their genetic resources and manage genetic variation in their breeding program. The recent advances in sequencing technology provide the opportunity to identify tens or hundreds of thousands of single nucleotide polymorphism (SNPs) in large genome species (e.g., wheat). These SNPs can be utilized for understanding genetic diversity and performing genome wide association studies (GWAS) for complex traits. In this study, the genetic diversity and population structure were investigated in a set of 230 genotypes (F3:6) derived from various crosses as a prerequisite for GWAS and genomic selection. Genotyping-by-sequencing provided 25,566 high-quality SNPs. The polymorphism information content (PIC) across chromosomes ranged from 0.09 to 0.37 with an average of 0.23. The distribution of SNPs markers on the 21 chromosomes ranged from 319 on chromosome 3D to 2,370 on chromosome 3B. The analysis of population structure revealed three subpopulations (G1, G2, and G3). Analysis of molecular variance identified 8% variance among and 92% within subpopulations. Of the three subpopulations, G2 had the highest level of genetic diversity based on three genetic diversity indices: Shannon’s information index (I) = 0.494, diversity index (h) = 0.328 and unbiased diversity index (uh) = 0.331, while G3 had lowest level of genetic diversity (I = 0.348, h = 0.226 and uh = 0.236). This high genetic diversity identified among the subpopulations can be used to develop new wheat cultivars.

Tectonic Imprints of the Hazara Kashmir Syntaxis on the Mesozoic Rocks Exposed in Munda, Mohmand Agency, Northwest Pakistan

AbstractTwo well‐developed mesoscopic folds, D2 and D3, which postdate the middle amphibolite metamorphism, were recognized in the western hinterland zone of Pakistan. NW–SE trending D2 folds developed during NE–SW horizontal bulk shortening followed by NE–SW trending D3 folds, which developed during SE–NW shortening. Micro‐ to mesoscopically the NW–SE trending S2 crenulation cleavage, boudins and mineral stretching lineations are overprinted by D3. The newly established NW–SE trending micro‐ to mesoscopic structures in Munda termed D2, which postdated F1/F2, is synchronously developed with F3 structures in the western hinterland zone of Pakistan. We interpret that D2 and D3 folds are counterclockwise rotated in the tectonic event that has evolved the Hazara Kashmir Syntaxis after the main phase Indian plate and Kohistan Island Arc collision. Chlorite replacement by biotite in the main matrix crenulation cleavages indicates prograde metamorphism related with D2. The inclusion of muscovite and biotite in garnet porphyroblasts and the presence of staurolite in these rocks indicate that the Barrovian metamorphic conditions predate D2 and D3. We interpret that garnet, staurolite and calcite porphyroblasts grew before D2 because the well developed S2 crenulation cleavage wraps around these porphyroblasts.

Geometric Scaling Analysis of Deep Inelastic Scattering Data Including Heavy Quarks**Supported by the National Natural Science Foundation of China under Grant Nos 11305040, 11375071 and 11447203, the Education Department of Guizhou Province Innovation Talent Fund under Grant No [2015]5508, the Education Department of Guizhou Province Innovation Team Fund under Grant No [2014]35, the Guizhou Province Science Technology Foundation under Grant

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.

Improved nonsinglet QCD analysis of fixed-target DIS data

Deep inelastic scattering data on F2 structure function obtained by BCDMS, SLAC and NMC collaborations in fixed-target experiments are analyzed in the non-singlet approximation with next-to-next-to-leading-order accuracy. The strong coupling constant is found to be , which is seen to be well compatible with the average world value. The results, obtained in the present paper by carrying out fits similar to what were performed in (B G Shaikhatdenov et al 2010 Phys. Rev. D 81 034008), with the exception for systematic errors in BCDMS data taken into account in a different way, confirm our previous ones derived in that same paper. This study is also meant to at least partially explain differences in the latest predictions for LHC observables, caused by usage of different sets of parton distribution functions obtained by different groups.

Strong coupling constant from QCD analysis of the fixed-target DIS data

Deep inelastic scattering data on F2 structure function obtained in fixed-target experiments were analyzed in the valence quark approximation with a next-to-next-to-leading-order accuracy. The strong coupling constant is found to be αs (MZ2) = 0.1157 ± 0.0022 (total experimental error), which is seen to be well compatible with the average world value. This study is meant to at least partially explain differences in the predictions for observables at the LHC found recently, caused by usage of various sets of parton distribution functions obtained by different groups.

Zero thermal expansion and ferromagnetism in cubic Sc(1-x)M(x)F3 (M = Ga, Fe) over a wide temperature range.

The rare physical property of zero thermal expansion (ZTE) is intriguing because neither expansion nor contraction occurs with temperature fluctuations. Most ZTE, however, occurs below room temperature. It is a great challenge to achieve isotropic ZTE at high temperatures. Here we report the unconventional isotropic ZTE in the cubic (Sc1-xMx)F3 (M = Ga, Fe) over a wide temperature range (linear coefficient of thermal expansion (CTE), αl = 2.34 × 10(-7) K(-1), 300-900 K). Such a broad temperature range with a considerably negligible CTE has rarely been documented. The present ZTE property has been designed using the introduction of local distortions in the macroscopic cubic lattice by heterogeneous cation substitution for the Sc site. Even though the macroscopic crystallographic structure of (Sc0.85Ga0.05Fe0.1)F3 adheres to the cubic system (Pm3̅m) according to the results of X-ray diffraction, the local structure exhibits a slight rhombohedral distortion. This is confirmed by pair distribution function analysis of synchrotron radiation X-ray total scattering. This local distortion may weaken the contribution from the transverse thermal vibration of fluorine atoms to negative thermal expansion, and thus may presumably be responsible for the ZTE. In addition, the present ZTE compounds of (Sc1-xMx)F3 can be functionalized to exhibit high-Tc ferromagnetism and a narrow-gap semiconductor feature. The present study shows the possibility of obtaining ZTE materials with multifunctionality in future work.

Analytical solution of Dokshitzer–Gribov–Lipatov–Altarelli–Parisi evolution equation for xF 3(x, Q 2) structure functions at low x and low Q 2 using a Q 2 dependent Regge ansatz

Using a Q 2 dependent Regge ansatz for xF 3(x, Q 2) structure function, developed on the basis of observed similarity between the Q 2 behavior of F 2(x, Q 2) and xF 3(x, Q 2) structure functions at low x and low Q 2, Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution equation is solved analytically. The solutions are analyzed phenomenologically in comparison with experimental data taken from CCFR and NuTeV collaborations and it is observed that application of the Regge ansatz in DGLAP evolution equation leads to a very good agreement with experimental data.