Inclusive Production Cross Section Research Articles

Phenomenology of single-inclusive jet production with jet radius and threshold resummation

We perform a detailed study of inclusive jet production cross sections at the LHC and compare the QCD theory predictions based on the recently developed formalism for threshold and jet radius joint resummation at next-to-leading logarithmic accuracy to inclusive jet data collected by the CMS collaboration at $\sqrt{S} = 7$ and $13$TeV. We compute the cross sections at next-to-leading order in QCD with and without the joint resummation for different choices of jet radii $R$ and observe that the joint resummation leads to crucial improvements in the description of the data. Comprehensive studies with different parton distribution functions demonstrate the necessity of considering the joint resummation in fits of those functions based on the LHC jet data.

Σ0 production in proton nucleus collisions near threshold

The production of Σ0 baryons in the nuclear reaction p (3.5 GeV) + Nb (corresponding to sNN=3.18 GeV) is studied with the detector set-up HADES at GSI, Darmstadt. Σ0s were identified via the decay Σ0→Λγ with subsequent decays Λ→pπ− in coincidence with a e+e− pair from either external (γ→e+e−) or internal (Dalitz decay γ⁎→e+e−) gamma conversions. The differential Σ0 cross section integrated over the detector acceptance, i.e. the rapidity interval 0.5<y<1.1, has been extracted as ΔσΣ0=2.3±(0.2)stat±(−0.6+0.6)sys±(0.2)norm mb, yielding the inclusive production cross section in full phase space σΣ0total=5.8±(0.5)stat±(−1.4+1.4)sys±(0.6)norm±(1.7)extrapol mb by averaging over different extrapolation methods. The Λall/Σ0 ratio within the HADES acceptance is equal to 2.3±(0.2)stat±(−0.6+0.6)sys. The obtained rapidity and momentum distributions are compared to transport model calculations. The Σ0 yield agrees with the statistical model of particle production in nuclear reactions.

Constraints on the double-parton scattering cross section from same-sign W boson pair production in proton-proton collisions at sqrt{s}=8 TeV

A first search for same-sign WW production via double-parton scattering is performed based on proton-proton collision data at a center-of-mass energy of 8 TeV using dimuon and electron-muon final states. The search is based on the analysis of data corresponding to an integrated luminosity of 19.7 fb−1. No significant excess of events is observed above the expected single-parton scattering yields. A 95% confidence level upper limit of 0.32 pb is set on the inclusive cross section for same-sign WW production via the double-parton scattering process. This upper limit is used to place a 95% confidence level lower limit of 12.2 mb on the effective double-parton cross section parameter, closely related to the transverse distribution of partons in the proton. This limit on the effective cross section is consistent with previous measurements as well as with Monte Carlo event generator predictions.

Highlights of top quark measurements in hadronic final states at ATLAS

Measurements of inclusive and differential top quark production cross sections in hadronic final states, including hadronic τ decays, in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented at center-of-mass energies of 7, 8 and 13 TeV. The inclusive cross section measurements reach high precision and are compared to other decay modes and the best available theoretical calculations. Differential measurements of the kinematic properties of top quark events are also discussed. These measurements use boosted top quarks, probing our understanding of top quark production in the TeV regime.

αs from top-quark pair production at hadron colliders

The strong coupling constant αs(MZ) is determined using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Individual values of αs(MZ) are extracted from measurements of different experiments at several centre-of-mass energies, using QCD predictions complete in NNLO perturbation theory, supplemented with NNLL approximations to all orders, and suitable sets of parton distribution functions. These values are then combined using a likelyhood-based approach, with special emphasis on a consistent treatment of systemtic uncertainties and their correlations. The final combined result is αs(MZ)=0.1177−0.0036+0.0034.

Measurement of the inclusive-isolated prompt-photon cross section in pp¯ collisions using the full CDF data set

A measurement of the inclusive production cross section of isolated prompt photons in proton-antiproton collisions at center-of-mass energy s=1.96 TeV is presented. The results are obtained using the full Run II data sample collected with the Collider Detector at the Fermilab Tevatron, which corresponds to an integrated luminosity of 9.5 fb−1. The cross section is measured as a function of photon transverse energy, ETγ, in the range 30<ETγ<500 GeV and in the pseudorapidity region |ηγ|<1.0. The results are compared with predictions from parton-shower Monte Carlo models at leading order in QCD and from next-to-leading-order perturbative QCD calculations. The latter show good agreement with the measured cross section.Received 1 March 2017DOI:https://doi.org/10.1103/PhysRevD.96.092003© 2017 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle phenomenaParticles & Fields

Inclusive production through AdS/CFT

It has been shown that AdS/CFT calculations can reproduce certain exclusive 2→2 cross sections in QCD at high energy, both for near-forward and for fixed-angle scattering. In this paper, we extend prior treatments by using AdS/CFT to calculate the inclusive single-particle production cross section in QCD at high center-of-mass energy. We find that conformal invariance in the UV restricts the cross section to have a characteristic power-law falloff in the transverse momentum of the produced particle, with the exponent given by twice the conformal dimension of the produced particle, independent of incoming particle types. We conclude by comparing our findings to recent LHC experimental data from ATLAS and ALICE, and find good agreement.

Determination of the strong coupling constant alpha _s left( m_Z right) from measurements of the total cross section for top\u2013antitop-quark production

We present a determination of the strong coupling constant alpha _s left( m_Z right) using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Following a procedure first applied by the CMS Collaboration, we extract individual values of alpha _s left( m_Z right) from measurements by different experiments at several centre-of-mass energies, using QCD predictions complete in NNLO perturbation theory, supplemented with NNLL approximations to all orders, and suitable sets of parton distribution functions. The determinations are then combined using a likelihood-based approach, where special emphasis is put on a consistent treatment of theoretical uncertainties and of correlations between various sources of systematic uncertainties. Our final combined result is alpha _s left( m_Z right) =0.1177^{+0.0034{}}_{-0.0036{}}.

Measurement of the inclusive jet cross-sections in proton-proton collisions at sqrt{s}=8 TeV with the ATLAS detector

Inclusive jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of sqrt{s}=8 TeV recorded by the ATLAS experiment at the Large Hadron Collider at CERN. The total integrated luminosity of the analysed data set amounts to 20.2 fb−1. Double-differential cross-sections are measured for jets defined by the anti-kt jet clustering algorithm with radius parameters of R = 0.4 and R = 0.6 and are presented as a function of the jet transverse momentum, in the range between 70 GeV and 2.5 TeV and in six bins of the absolute jet rapidity, between 0 and 3.0. The measured cross-sections are compared to predictions of quantum chromodynamics, calculated at next-to-leading order in perturbation theory, and corrected for non-perturbative and electroweak effects. The level of agreement with predictions, using a selection of different parton distribution functions for the proton, is quantified. Tensions between the data and the theory predictions are observed.

Measurement of the inclusive energy spectrum in the very forward direction in proton-proton collisions at sqrt{s}=13 TeV

The differential cross section for inclusive particle production as a function of energy in proton-proton collisions at a center-of-mass energy of 13 TeV is measured in the very forward region of the CMS detector. The measurement is based on data collected with the CMS apparatus at the LHC, and corresponds to an integrated luminosity of 0.34 μb−1. The energy is measured in the CASTOR calorimeter, which covers the pseudorapidity region −6.6 < η < −5.2. The results are given as a function of the total energy deposited in CASTOR, as well as of its electromagnetic and hadronic components. The spectra are sensitive to the modeling of multiparton interactions in pp collisions, and provide new constraints for hadronic interaction models used in collider and in high energy cosmic ray physics.

Measurement of Inclusive Charged Jet Production in pp and Pb–Pb collisions at [formula omitted] with ALICE

In these proceedings, we report the ALICE measurements of inclusive charged jet production in pp and Pb-Pb collisions at the currently highest available centre-of-mass energy at the LHC of 5.02 TeV. Charged jet spectra are extracted after jet-area based soft background subtraction and unfolding. Charged jet production cross sections as well as nuclear modification factors (RAA) are presented. Furthermore, the inclusive charged jet production cross section in pp collisions is compared to QCD calculations. Our RAA results show a significant jet suppression in the most central Pb-Pb collisions at 5.02 TeV. A comparison to RAA measurements obtained at lower centre-of-mass energy is also presented.

Implementation of NLO high energy factorization in single inclusive forward hadron production

Single inclusive particle production cross sections in high energy hadron collisions at forward rapidity are an important benchmark process for the CGC picture of small x QCD. Recent calculations of this process have not led to a stable perturbative expansion for this quantity at high transverse momenta. We consider the quark channel production cross section using the new rapidity factorization procedure proposed by Iancu et al. We show that for fixed coupling one does indeed obtain a physically meaningful cross section which is positive and reduces in a controlled way to previous leading order calculations. We also consider a running coupling that depends on the transverse momentum of the produced particle. This gives a stable result which, however, is not fully consistent with previous leading order calculations that use a coordinate space running coupling.

Measurement of the differential inclusive B+ hadron cross sections in pp collisions at [formula omitted

The differential cross sections for inclusive production of B+ hadrons are measured as a function of the B+ transverse momentum pTB and rapidity yB in pp collisions at a centre-of-mass energy of 13 TeV, using data collected by the CMS experiment that correspond to an integrated luminosity of 48.1 pb−1. The measurement uses the exclusive decay channel B+→J/ψK+, with J/ψ mesons that decay to a pair of muons. The results show a reasonable agreement with theoretical calculations within the uncertainties.

Measurement of the cross section for inclusive isolated-photon production in pp collisions at [formula omitted] using the ATLAS detector

Inclusive isolated-photon production in pp collisions at a centre-of-mass energy of 13 TeV is studied with the ATLAS detector at the LHC using a data set with an integrated luminosity of 3.2 fb−1. The cross section is measured as a function of the photon transverse energy above 125 GeV in different regions of photon pseudorapidity. Next-to-leading-order perturbative QCD and Monte Carlo event-generator predictions are compared to the cross-section measurements and provide an adequate description of the data.

Phenomenology of on-shell Higgs production in the MSSM with complex parameters

A computation of inclusive cross sections for neutral Higgs boson production through gluon fusion and bottom-quark annihilation is presented in the MSSM with complex parameters. The predictions for the gluon-fusion process are based on an explicit calculation of the leading-order cross section for arbitrary complex parameters which is supplemented by higher-order corrections: massive top- and bottom-quark contributions at NLO QCD, in the heavy top-quark effective theory the top-quark contribution up to N^{3}LO QCD including a soft expansion for the mathcal {CP}-even component of the light Higgs boson. For its mathcal {CP}-odd component and the heavy Higgs bosons the contributions are incorporated up to NNLO QCD. Two-loop electroweak effects are also incorporated, and SUSY QCD corrections at NLO are interpolated from the MSSM with real parameters. Finite wave function normalisation factors ensuring correct on-shell properties of the external Higgs bosons are incorporated from the code FeynHiggs. For the typical case of a strong admixture of the two heavy Higgs bosons it is demonstrated that squark effects are strongly dependent on the phases of the complex parameters. The remaining theoretical uncertainties for cross sections are discussed. The results have been implemented into an extension of the numerical code SusHi called SusHiMi.

Exploring minijets beyond the leading power

The crucial parameter of the current Monte Carlo models of high energy hadron-hadron interaction is the transverse momentum cutoff $p_{T0}$ for parton-parton interactions which slowly grows with energy and regularizes the cross section. This modification of the collinear factorization formula goes beyond the leading power and thus a natural question arises if such cutoff can be extracted from a formalism which takes into account power corrections. In this work, we consider the High Energy Factorization (HEF) valid at small $x$ and a new model, based on a similar principle to HEF, which in addition has a limit respecting the Dokshitzer-Dyakonov-Troyan formula for the dijet momentum disbalance spectrum. Minijet cross section and its suppression is then analyzed in two ways. First, we study minijets directly in the low-$p_T$ region, and demonstrate that higher twist corrections do generate suppression of the inclusive jet production cross section though these effects are not leading to the increase of the cutoff with incident energy. Second, we consider hard inclusive dijet production where Multi Parton Interactions (MPIs) with minijets produce power corrections. We introduce an observable constructed from differential cross section in the ratio $\tau$ of dijet disbalance to the average dijet $p_T$ and demonstrate that the $\tau>1$ region is sensitive to the cutoff $p_{T0}$ in the MPI minijet models. The energy dependence of the cutoff is reflected in the energy dependence of the bimodality coefficient $b$ of the $\tau$ distribution. We compare $b$ calculated from $\mathsf{pythia}$, where one can conveniently control MPIs by the program parameters, and HEF for a few unintegrated gluon distributions (UGDs). We find that the energy dependence of $b$ is very sensitive to the particular choice of UGD and in some models it resembles predictions of the Monte Carlo models.

Direct Photon Production in Pion-Proton Collisions

In this article we calculate the contribution of the higher-twist Feynman diagrams to the large-pT inclusive single direct photon production cross section in πp collisions in case of the running coupling and frozen coupling approaches within holographic QCD. We determined the structure of infrared renormalon singularities of the higher-twist subprocess cross section. Also compared and analyzed the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach.

Top Physics at CMS/LHC

Recent results on the inclusive and differential production cross sections of top-quark pair and single top-quark processes are presented, obtained using data from proton-proton collisions collected with the CMS detector at the LHC. The large centre-of-mass energies available at LHC allow for the copious production of top-quark pairs in association with other final state particles at high transverse momentum. Measurements of such processes as well as of the top-quark mass and other properties will be discussed. The results are compared with the most up-to-date standard model theory predictions.

Measurement of the inclusivett¯production cross section inpp¯collisions ats=1.96 TeVand determination of the top quark pole mass

The inclusive cross section of top quark-antiquark pairs produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is measured in the lepton$+$jets and dilepton decay channels. The data sample corresponds to 9.7 fb${}^{-1}$ of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Employing multivariate analysis techniques we measure the cross section in the two decay channels and we perform a combined cross section measurement. For a top quark mass of 172.5 GeV, we measure a combined inclusive top quark-antiquark pair production cross section of $\sigma_{t\bar{t}} = 7.26 \pm 0.13\,(\mathrm{stat.})\,^{+0.57}_{-0.50}\,(\mathrm{syst.})$ pb which is consistent with standard model predictions. We also perform a likelihood fit to the measured and predicted top quark mass dependence of the inclusive cross section, which yields a measurement of the pole mass of the top quark. The extracted value is $m_t = 172.8 \pm 1.1\,(\mathrm{theo.})\,^{+3.3}_{-3.1}\,(\mathrm{exp.})$ GeV.

SusHi Bento: Beyond NNLO and the heavy- top limit

Version 1.6.0 of the code SusHi is presented. Concerning inclusive CP-even Higgs production in gluon fusion, the following new features with respect to previous versions have been implemented: expansion of the partonic cross section in the soft limit, i.e. around x=MH2∕sˆ→1; N3LO QCD corrections in terms of the soft expansion; top-quark mass suppressed terms through NNLO; matching to the cross section at x→0 through N3LO. For CP-even and -odd scalars, an efficient evaluation of the renormalization-scale dependence is included, and effects of dimension-5 operators can be studied, which we demonstrate for the SM Higgs boson and for a CP-even scalar with a mass of 750GeV. In addition, as a generalization of the previously available bb̄→H cross section, SusHi_1.6.0 provides the cross section for charged and neutral Higgs production in the annihilation of arbitrary heavy quarks. At fixed order in perturbation theory, SusHi thus allows to obtain Higgs cross-section predictions in different models to the highest precision known today. For the SM Higgs boson of MH=125GeV, SusHi yields 48.28 pb for the gluon-fusion cross section at the LHC at 13TeV. Simultaneously, SusHi provides the renormalization-scale uncertainty of ±1.97pb. New version program summaryProgram title:SusHi.Program Files doi:http://dx.doi.org/10.17632/3bb3z4k9hp.1Licensing provisions: GNU General Public License 3 (GPL).Programming language: Fortran 77.Journal Reference of previous version: Comp. Phys. Comm. 184, Issue 6 (2013) 1605–1617Does the new version supersede the previous version?: Yes. The new version also includes all features of previous versions.Reasons for the new version:Compared to version 1.0.0 the newest SusHi version 1.6.0 now supports the 2-Higgs-Doublet-Model (2HDM) and the next-to-minimal supersymmetric standard model (NMSSM). The effects of dimension-5 operators in the calculation of the gluon-fusion cross section can be studied. It allows to calculate the Higgs production cross section from the annihilation of heavy quarks and includes various new features which improve the gluon-fusion cross-section prediction and the associated uncertainty estimate. Links to external codes 2HDMC, MoRe-SusHi and MadGraph5_aMC@NLO can be established.Summary of revisions:Inclusion of 2HDM, NMSSM; Improvements in the prediction of the gluon-fusion cross section: Top-quark mass terms up to next-to-next-to leading order, soft expansion and next-to-next-to-next-to leading order corrections in the heavy top-quark effective theory, top squark corrections up to next-to-next-to leading order; dimension-5 operators; analytic determination of the renormalization scale dependence. Inclusion of heavy-quark annihilation cross sections. Link to MoRe-SusHi for the calculation of resummed transverse-momentum distributions.Nature of problem:Calculation of inclusive and exclusive Higgs production cross sections in gluon fusion and heavy-quark annihilation in the SM and extended Higgs sectors through next-to-leading order QCD, including (next-to-)next-to-next-to-leading order top-(s)quark contributions and electroweak effects.Solution method: Numerical Monte Carlo integration.