Cross Section For Pp Research Articles

QCD corrections to Higgs boson production and H→bb¯ decay in weak boson fusion

We study QCD corrections to the process where a Higgs boson is produced in weak boson fusion and then decays into a pair of massive b quarks. We find that typical experimental criteria used to identify b jets in this process affect QCD corrections to the decay, making it necessary to account for them in the proper description of this process. Indeed, if corrections to the production and decay are combined, the fiducial cross section of the weak boson fusion process pp→H(→bb¯)jj is reduced by about 40% relative to leading-order predictions, compared to just about 8% if only corrections to the production process are considered. We investigate the origin of these large corrections through next-to-next-to-leading order and conclude that they appear because a number of independent moderately large effects conspire to significantly reduce the fiducial cross section for this process. Published by the American Physical Society 2024

Interpretation of excess in H→Zγ using a light axionlike particle

We interpret the recent excess in a rare decay of the Higgs boson, H→Zγ, using a light axionlike particle (ALP) in the mass range 0.05–0.1 GeV. The dominant decay of such a light ALP is into a pair of collimated photons, whose decay is required to happen before reaching the ECAL detector, such that it mimics a single photon in the detector. It can explain the excess with a coupling CaZHeff/Λ∼4×10−5 GeV−1, while the decay of the ALP before reaching the ECAL requires the diphoton coupling Cγγeff/Λ≥0.35 TeV−1(0.1 GeV/ma)2. A potential test would be the rare decay of the Z boson Z→aH*→a(bb¯) at the Tera-Z option of the future FCC and CEPC. However, it has a branching ratio of only O(10−12), and thus barely testable. The production cross section for pp→Z*→aH via the same coupling CaZHeff/Λ at the LHC is too small for detection. Published by the American Physical Society 2024

Axion-pion scattering at finite temperature in chiral perturbation theory and its influence in axion thermalization

Axion-pion scattering amplitudes at finite temperatures are calculated within chiral perturbation theory up to the one loop level. Unitarization procedure is implemented to these amplitudes in order to extend the applicable range of energy and temperature. The influence of the thermal axion-pion scattering amplitudes on the aπ→ππ cross sections and the axion thermalization rate is investigated, with the emphasis on the comparison with the zero-temperature-amplitude case. A brief discussion on the cosmological implication of the axion thermalization rate, which is calculated by using the aπ→ππ amplitudes at finite temperatures, is also given. The thermal corrections to the axion-pion scattering amplitudes can cause around a 10% shift of the determination of the axion decay constant fa and its mass ma, comparing with the results by using the aπ→ππ amplitudes at zero temperature. Published by the American Physical Society 2024

Meson production in J/ψ decays and [formula omitted] process

It is shown that an account for the final-state interaction of real or virtual nucleon and antinucleon produced in the processes J/ψ→pp¯γ, ψ(2S)→pp¯γ, J/ψ→pp¯ω, and J/ψ→3(π+π−)γ near the threshold of NN¯ pair production allows one to obtain self-consistent description of these processes. Predictions of our model are in good agreement with experimental data available. The proposed potential model also reproduces the corresponding partial cross sections of pp¯ scattering.

Search for Higgs boson pair production in the two bottom quarks plus two photons final state in pp collisions at [formula omitted] TeV with the ATLAS detector

Searches for nonresonant and resonant di-Higgs boson production are performed in the bb¯γγ final state. The data set used corresponds to an integrated luminosity of 139 fb−1 of proton–proton collisions at 13 TeV center-of-mass energy recorded by the ATLAS detector at the CERN Large Hadron Collider. No excess above the expected background is found and upper limits on the di-Higgs boson production cross sections are set.For pp→HH nonresonant production, a 95% confidence-level upper limit of 4.2 times the cross section predicted by the Standard Model is set, where the expected limit is 5.7 times the Standard Model predicted value. The expected constraints are obtained for a background hypothesis excluding pp→HH production. The observed (expected) constraints on the Higgs boson trilinear coupling modifier κλ are determined to be [−1.5,6.7]([−2.4,7.7]) at 95% confidence level, where the expected constraints on κλ are obtained excluding pp→HH production from the background hypothesis.For resonant production of a new hypothetical scalar particle X (X→HH→bb¯γγ), limits on the cross section for pp→X→HH are presented in the narrow-width approximation as a function of mX in the range 251≤mX≤1000 GeV. The observed (expected) limits on the cross section for pp→X→HH range from 640 fb to 44 fb (391 fb to 46 fb) over the considered mass range.

Exclusive diffractive bremsstrahlung of one and two photons at forward rapidities: Possibilities for experimental studies in pp collisions at the LHC

We evaluate the cross section for diffractive bremsstrahlung of a single photon in the pp→ppγ reaction at high energies and at forward photon rapidities. Several differential distributions, for instance, in y, k⊥ and ω, the rapidity, the absolute value of the transverse momentum, and the energy of the photon, respectively, are presented. We compare the results for our standard approach, based on QFT and the tensor-pomeron model, with two versions of soft-photon-approximations, SPA1 and SPA2, where the radiative amplitudes contain only the leading terms proportional to ω−1. The SPA1, which does not have the correct energy-momentum relations, performs surprisingly well in the kinematic range considered. We discuss also azimuthal correlations between outgoing particles. The azimuthal distributions are not isotropic and are different for our standard model and SPAs. We discuss also the possibility of a measurement of two-photon-bremsstrahlung in the pp→ppγγ reaction. In our calculations we impose a cut on the relative energy loss (0.02<ξi<0.1, i=1,2) of the protons where measurements by the ATLAS Forward Proton (AFP) detectors are possible. The AFP requirement for both diffractively scattered protons and one forward photon (measured at LHCf) reduces the cross section for pp→ppγ almost to zero. On the other hand, much less cross-section reduction occurs for pp→ppγγ when photons are emitted in opposite sides of the ATLAS interaction point and can be measured by two different arms of LHCf. For the SPA1 ansatz we find σ(pp→ppγγ)≃0.03 nb at s=13 TeV and with the cuts 0.02<ξi<0.1, 8.5<y3<9, −9<y4<−8.5. Our predictions can be verified by ATLAS and LHCf combined experiments. We discuss also the role of the pp→ppπ0 background for single photon production.

Toward a better understanding of microalgal photosynthesis in medium polluted with microplastics: a study of the radiative properties of microplastic particles.

Due to the wide presence of microplastics in water, the interaction between microplastic particles and microalgae cells in medium merits the attention of researchers. Microplastic particles can impact the original transmission of light radiation in water bodies since the refractive index of microplastics is different from that of water bodies. Accordingly, the accumulation of microplastics in water bodies will certainly impact microalgal photosynthesis. Therefore, experimental measurements and theoretical studies characterizing the radiative properties of the interaction between light and microplastic particles are highly significant. The extinction and absorption coefficient/cross-section of polyethylene terephthalate and polypropylene were experimentally measured using transmission and integrating methods in the spectral range of 200-1,100nm. The absorption cross-section of PET shows remarkable absorption peaks in the vicinity of 326nm, 700nm, 711nm, 767nm, 823nm, 913nm, and 1,046nm. The absorption cross-section of PP has distinctive absorption peaks near 334nm, 703nm, and 1,016nm. The measured scattering albedo of the microplastic particles is above 0.7, indicating that both microplastics are scattering dominant media. Based on the results of this work, an in-depth understanding of the interaction between microalgal photosynthesis and microplastic particles in the medium will be obtained.

Fresh look at experimental evidence for odderon exchange

Theory suggests that in high-energy elastic hadron+hadron scattering, t-channel exchange of a family of colourless crossing-odd states – the odderon – may generate differences between pp¯ and pp cross-sections in the neighbourhood of the diffractive minimum. Using a mathematical approach based on interpolation via continued fractions enhanced by statistical sampling, we develop robust comparisons between pp¯ elastic differential cross-sections measured at √s=1.96 TeV by the D0 Collaboration at the Tevatron and function-form-unbiased extrapolations to this energy of kindred pp measurements at √s/TeV=2.76,7,8,13 by the TOTEM Collaboration at the LHC and a combination of these data with earlier cross-section measurements at √s/GeV=23.5,30.7,44.7,52.8,62.5 made at the intersecting storage rings. Focusing on a domain that straddles the diffractive minimum in the pp¯ and pp cross-sections, we find that these two cross-sections differ at the (2.2−2.6)σ level; hence, supply evidence with this level of significance for the existence of the odderon. If combined with evidence obtained through different experiment-theory comparisons, whose significance is reported to lie in the range (3.4−4.6)σ, one arrives at a (4.0−5.2)σ signal for the odderon.

Analysis procedures in deriving of the differential cross section of the reaction pp ! {pp}sp0 at energies 1.6–2.4 GeV

The reaction pp → {pp} s p 0 , where {pp}s denotes a diproton, i.e. an unbound interacting proton pair in the 1 S 0 , state, was investigated in order to obtain a differential cross section ds/dW at small angles in the energy range 1.6–2.4 GeV. This work is intended for the presentation of the main procedures in the processing of experimental data.

Elucidating the jet cross-section in pp and pPb collisions at sNN = 5.02TeV

In this paper, we present the charged particles jet cross-section study in [Formula: see text] and [Formula: see text] collisions at [Formula: see text],TeV using PYTHIA8 (PYTHIA8.186 and PYTHIA8.306) and HIJING 2.0 models, in kinematic range of [Formula: see text],GeV/c for [Formula: see text] collisions and [Formula: see text],GeV/c for [Formula: see text] collisions. The jets are reconstructed for [Formula: see text], 0.3, 0.4 and 0.6 for the pseudorapidity interval of [Formula: see text] 0.9-R. The jets algorithms: cell jet and slow jet inside PYTHIA8.186 and anti-[Formula: see text] algorithm using HIJING 2.0 have been used for Monte Carlo simulations. The simulation results are then compared with measurements of the ALICE experiment. It is observed that all models’ predictions are lower than experimental data up to [Formula: see text],GeV/c; after that, the Monte Carlo study of Cell and slow jet satisfies the experimental data. The CR tunes could not explain the ALICE data at high [Formula: see text] values due to nonperturbative QCD effects. We have also calculated the nuclear modification factor [Formula: see text], and no clear suppression has been seen in the case of [Formula: see text] collisions. The results from the models indicate that the QGP is not formed and that the cold nuclear matter effect exists in pPb collisions.

Search for Higgs boson pair production in the two bottom quarks plus two photons final state in pp collisions at s=13 TeV with the ATLAS detector

Searches are performed for nonresonant and resonant di-Higgs boson production in the bb¯γγ final state. The dataset used corresponds to an integrated luminosity of 139 fb−1 of proton–proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No excess above the expected background is found and upper limits on the di-Higgs boson production cross sections are set. A 95% confidence-level upper limit of 4.2 times the cross section predicted by the Standard Model is set on pp→HH nonresonant production, where the expected limit is 5.7 times the Standard Model predicted value. The expected constraints are obtained for a background hypothesis excluding pp→HH production. The observed (expected) constraints on the Higgs boson trilinear coupling modifier κλ are determined to be [−1.5,6.7] ([−2.4,7.7]) at 95% confidence level, where the expected constraints on κλ are obtained excluding pp→HH production from the background hypothesis. For resonant production of a new hypothetical scalar particle X (X→HH→bb¯γγ), limits on the cross section for pp→X→HH are presented in the narrow-width approximation as a function of mX in the range 251 GeV≤mX≤1000 GeV. The observed (expected) limits on the cross section for pp→X→HH range from 640 fb to 44 fb (391 fb to 46 fb) over the considered mass range.8 MoreReceived 23 December 2021Accepted 1 August 2022DOI:https://doi.org/10.1103/PhysRevD.106.052001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.© 2022 CERN, for the ATLAS CollaborationPhysics Subject Headings (PhySH)Research AreasExtensions of Higgs sectorHadron-hadron interactionsPhysical SystemsHiggs bosonsParticles & Fields

結晶相の形状不均一性を考慮した結晶性ポリマの寸法依存性に関する分子鎖塑性FEM解析

Crystalline polymers may show different deformation responses depending on size of crystalline phase with respect to that of specimen. In the previous report, experimental stress-strain curves are numerically reproduced by the molecular chain plasticity FE analysis using a unit cell with hexagonal crystalline phases. However, there are some problems that the shape of crystalline phase in the unit cell is not always 6-fold symmetrical in the actual two-dimensional cross section of PP and the effect of the shape heterogeneity of crystalline phases on deformation responses has not been clarified. In the present report, the authors change the shape of some crystalline phase in the unit cell from hexagon to square and attempt to conduct the molecular chain plasticity FE analysis for amorphous phase and crystal plasticity FE analysis for crystalline one. Furthermore, the effect of shape heterogeneity of crystalline phases on deformation responses is investigated by comparing the results for unit cells with different heterogeneity.

Λc+ production in pp and in p -Pb collisions at sNN=5.02 TeV

The production cross section of prompt $\mathrm{\Lambda_{c}^{+}}$ charm baryons was measured with the ALICE detector at the LHC at midrapidity in proton-proton (pp) and proton-lead (p-Pb) collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_\mathrm{NN}} = 5.02$ TeV. The $\mathrm{\Lambda_{c}^{+}}$ and $\rm {\overline{\Lambda}{}_c^-}$ baryons were reconstructed in the hadronic decay channels $\rm \Lambda_{c}^{+} \rightarrow p K^{-}\pi^{+}$ and $\rm \Lambda_{c}^{+}\to p K^{0}_{S}$ and respective charge conjugates. The measured differential cross sections as a function of transverse momentum ($p_{\rm T}$) and the $p_{\rm T}$-integrated $\mathrm{\Lambda_{c}^{+}}$ production cross section in pp and in p-Pb collisions are presented. The $\mathrm{\Lambda_{c}^{+}}$ nuclear modification factor ($R_\mathrm{pPb}$), calculated from the cross sections in pp and in p-Pb collisions, is presented and compared with the $R_\mathrm{pPb}$ of D mesons. The $\mathrm {\Lambda_{c}^{+}}/\mathrm {D^0}$ ratio is also presented and compared with the light-flavour baryon-to-meson ratios p$/\pi$ and $\Lambda /\mathrm {K^0_S}$, and measurements from other LHC experiments. The results are compared to predictions from model calculations and Monte Carlo event generators.

Unitarisation dependence of diffractive scattering in light of high-energy collider data

We study the consequences of high-energy collider data on the best fits to total, elastic, inelastic, and single-diffractive cross sections for pp and poverline{p} scattering using different unitarisation schemes. We find that the data are well fitted both by eikonal and U-matrix schemes, but that diffractive data prefer the U-matrix. Both schemes may be generalised by means of an additional parameter; however, this yields only marginal improvements to the fits. We provide estimates for ρ, the ratio of the real part to the imaginary part of the elastic amplitude, for the different fits. We comment on the effect of the different schemes on present and future cosmic ray data.

Evidence of Odderon-exchange from scaling properties of elastic scattering at TeV energies

We study the scaling properties of the differential cross section of elastic proton–proton (pp) and proton–antiproton (pbar{p}) collisions at high energies. We introduce a new scaling function, that scales – within the experimental errors – all the ISR data on elastic pp scattering from sqrt{s} = 23.5–62.5 GeV to the same universal curve. We explore the scaling properties of the differential cross-sections of the elastic pp and pbar{p} collisions in a limited TeV energy range. Rescaling the TOTEM pp data from sqrt{s} = 7 TeV to 2.76 and 1.96 TeV, and comparing it to D0 pbar{p} data at 1.96 TeV, our results provide an evidence for a t-channel Odderon exchange at TeV energies, with a significance of at least 6.26sigma . We complete this work with a model-dependent evaluation of the domain of validity of the new scaling and its violations. We find that the H(x) scaling is valid, model dependently, within 200~hbox {GeV}le sqrt{s} le 8 TeV, with a -t range gradually narrowing with decreasing colliding energies.

NLO QCD and EW corrections to vector-boson scattering into ZZ at the LHC

We present the first calculation of the full next-to-leading-order electroweak and QCD corrections for vector-boson scattering (VBS) into a pair of Z bosons at the LHC. We consider specifically the process pp → e+e−μ+μ−jj + X at orders mathcal{O} (α7) and mathcal{O} (αsα6) and take all off-shell and interference contributions into account. Owing to the presence of enhanced Sudakov logarithms, the electroweak corrections amount to −16% of the leading-order electroweak fiducial cross section and induce significant shape distortions of differential distributions. The QCD corrections on the other hand are larger (+24%) than typical QCD corrections in VBS. This originates from considering the full computation including tri-boson contributions in a rather inclusive phase space. We also provide a leading-order analysis of all contributions to the cross section for pp → e+e−μ+μ−jj + X in a realistic setup.

Measurement of the Z(\u2192 \u2113+\u2113\u2212)\u03b3 production cross-section in pp collisions at sqrt{s} = 13 TeV with the ATLAS detector

The production of a prompt photon in association with a Z boson is studied in proton-proton collisions at a centre-of-mass energy sqrt{s} = 13 TeV. The analysis uses a data sample with an integrated luminosity of 139 fb−1 collected by the ATLAS detector at the LHC from 2015 to 2018. The production cross-section for the process pp → ℓ+ℓ−γ + X (ℓ = e, μ) is measured within a fiducial phase-space region defined by kinematic requirements on the photon and the leptons, and by isolation requirements on the photon. An experimental precision of 2.9% is achieved for the fiducial cross-section. Differential cross-sections are measured as a function of each of six kinematic variables characterising the ℓ+ℓ−γ system. The data are compared with theoretical predictions based on next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations. The impact of next-to-leading-order electroweak corrections is also considered.

Interpretation of Yb(10750) as a tetraquark and its production mechanism

Recently, the Belle Collaboration has updated the analysis of the cross sections for the processes e+e−→ϒ(nS)π+π− (n=1,2,3) in the e+e− center-of-mass energy range from 10.52 to 11.02 GeV. A new structure, called here Yb(10750), with the mass M(Yb)=(10752.7±5.9−1.1+0.7) MeV and the Breit-Wigner width Γ(Yb)=(35.5−11.3−3.3+17.6+3.9) MeV was observed [1]. We interpret Yb(10750) as a compact JPC=1−− state with a dominant tetraquark component. The mass eigenstate Yb(10750) is treated as a linear combination of the diquark-antidiquark and bb¯ components due to the mixing via gluonic exchanges shown recently to arise in the limit of large number of quark colors. The mixing angle between Yb and ϒ(5S) can be estimated from the electronic width, recently determined to be Γee(Yb)=(13.7±1.8) eV. The mixing provides a plausible mechanism for Yb(10750) production in high energy collisions from its bb¯ component and we work out the Drell-Yan and prompt production cross sections for pp→Yb(10750)→ϒ(nS)π+π− at the LHC. The resonant part of the dipion invariant mass spectrum in Yb(10750)→ϒ(1S)π+π− and the corresponding angular distribution of π+-meson in the dipion rest frame are presented as an example.

The Tsallis entropy and the BKT-like phase transition in the impact parameter space for pp and collisions

In this paper, one uses the Tsallis entropy (TE) in the impact parameter space to study pp and inelastic overlap function and the energy density filling up mechanism responsible by the so-called black disk limit as the energy increases. The TE is non-additive and non-extensive and these features are of fundamental importance since the internal constituents of pp and are strongly correlated and also the existence of the multifractal character of the total cross-section. The entropy approach presented here takes into account a phase transition occurring inside the hadrons as the energy increases. This phase transition in the impact parameter space is quite similar to the Berezinskii–Kosterlitz–Thouless phase transition, possessing also a topological feature due to the multifractal dimension of the total cross-sections in pp and scattering.

Study of pp → 𝚵+ ΛK- with the PANDA Detector

For a deeper insight into the mechanisms of non-perturbative QCD it is essential to understand the excitation pattern of baryons. Up to now only the nucleon excitation spectrum has been subject to systematic experimental studies, while very little is known on excited states of double or triple strange baryons. In studies of antiproton-proton collisions the PANDA experiment is well-suited for a comprehensive baryon spectroscopy program in the multi-strange sector. A large fraction of the inelastic pp cross section is associated to final states with a baryon-antibaryon pair together with additional mesons, giving access to excited states both in the baryon and the antibaryon channel. For final states containing a 𝚵+ 𝚵- pair, cross sections up to µb are expected, corresponding to production rates of ~ 106/d at a luminosity L = 1031 cm-2 s-1. This study focuses on excited 𝚵- states decaying into ΛK-. A strategy to reconstruct the reaction pp → 𝚵+ 𝚵* and its charge conjugate channel with the PANDA detector will be presented.