scholarly journals Comprehensive studies of ϒ inclusive production in Z boson decay

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Zhan Sun ◽  
Hong Fei Zhang
Keyword(s):  
Z Boson ◽  
Inclusive Production ◽  
Color Singlet ◽  
Leading Order ◽  
Color Octet ◽  
Comprehensive Study ◽  
Comprehensive Studies

Abstract In this paper, we present a comprehensive study of ϒ inclusive production in Z boson decay, including the first complete next-to-leading-order calculations of the color-octet (CO) contributions. With the inclusion of the newly-calculated remarkable QCD corrections, the CO processes exhibit crucially phenomenological influence on the existing predictions built on the color-singlet mechanism. We also include the exhaustive evaluations of the feed-down contributions, which remained ignored in the literature, and find them to be considerable. Summing up all the contributions, the ℬZ → ϒ(nS) + X still notably undershoot the data released by the L3 Collaboration.

scholarly journals ηQ Meson Photoproduction in Ultrarelativistic Heavy Ion Collisions

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Gong-Ming Yu ◽  
Gao-Gao Zhao ◽  
Zhen Bai ◽  
Yan-Bing Cai ◽  
Hai-Tao Yang ◽  
...  
Keyword(s):  
Heavy Ion Collisions ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Heavy Quarkonium ◽  
Color Singlet ◽  
Initial State ◽  
Color Octet ◽  
Ion Collisions ◽  
The Matrix

The transverse momentum distributions for inclusive ηc,b meson described by gluon-gluon interactions from photoproduction processes in relativistic heavy ion collisions are calculated. We considered the color-singlet (CS) and color-octet (CO) components within the framework of Nonrelativistic Quantum Chromodynamics (NRQCD) in the production of heavy quarkonium. The phenomenological values of the matrix elements for the color-singlet and color-octet components give the main contribution to the production of heavy quarkonium from the gluon-gluon interaction caused by the emission of additional gluon in the initial state. The numerical results indicate that the contribution of photoproduction processes cannot be negligible for midrapidity in p-p and Pb-Pb collisions at the Large Hadron Collider (LHC) energies.

Charmonia production in W → (cc̄)Ds(∗) decays

2021 ◽  
Vol 36 (09) ◽  
pp. 2150058
Author(s):  
A. V. Luchinsky ◽  
A. K. Likhoded
Keyword(s):  
Quantum Chromodynamics ◽  
Light Cone ◽  
Relativistic Quantum ◽  
Branching Fractions ◽  
Color Singlet ◽  
Leading Order ◽  
Paper Production ◽  
Quantum Numbers ◽  
Numerical Predictions ◽  
State Formula

In this paper, production of charmonium state [Formula: see text] in exclusive [Formula: see text] decays is analyzed in the framework of both leading order Non-relativistic Quantum Chromodynamics (NRQCD) and light-cone (LC) expansion models. Analytical and numerical predictions for the branching fractions of these decays in both the approaches are given. The typical value of the branching fractions is [Formula: see text][Formula: see text][Formula: see text] and it turns out that the LC results are significantly larger than NRQCD ones (approximately two or four times increase depending on the quantum numbers of the final particles), so the effect of internal quark motion should be taken into account. Some rough estimates of color-octet contributions are presented and it is shown that these contributions could be comparable with color-singlet results.

scholarly journals Cross Section Prediction for Inclusive Production of Z Boson in pp Collisions at s=14 TeV: A Study of Systematic Uncertainty due to Scale Dependence

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Hasan Ogul ◽  
Kamuran Dilsiz
Keyword(s):  
Cross Section ◽  
Production Cross Section ◽  
Z Boson ◽  
Production Cross ◽  
Branching Ratio ◽  
Leading Order ◽  
Proton Proton ◽  
Proton Collisions ◽  
Central Values ◽  
Proton Proton Collisions

Prediction of Z→l+l- production cross section (where l±=e±,μ±) in proton-proton collisions at s=14 TeV is estimated up to next-to-next-to-leading order (NNLO) in perturbative QCD including next-to-leading order (NLO) electroweak (EW) corrections. The total inclusive Z boson production cross section times leptonic branching ratio, within the invariant mass window 66<mll<116 GeV, is predicted using NNLO HERAPDF2.0 at NNLO QCD and NLO EW as σZTot=2111.69-26.92+26.31 (PDF) ±11 (αs) ±17 (scale) -30.98+57.41 (parameterization and model). Theoretical prediction of the fiducial cross section is further computed with the latest modern PDF models (CT14, MMHT2014, NNPDF3.0, HERAPDF2.0, and ABM12) at NNLO for QCD and NLO for EW. The central values of the predictions are based on DYNNLO 1.5 program and the uncertainties are extracted using FEWZ 3.1 program. In addition, the cross section is also calculated as functions of μR and μF scales. The choice of μR and μF for scale variation uncertainty is further discussed in detail.

scholarly journals Quarkonium Production at Z0 and in ϒ(1S) Decay

1997 ◽  
Vol 12 (22) ◽  
pp. 3931-3940
Author(s):  
Kingman Cheung ◽  
Wai-Yee Keung ◽  
Tzu Chiang Yuan
Keyword(s):  
Color Singlet ◽  
Fixed Target ◽  
Production Rates ◽  
Fixed Target Experiments ◽  
Color Octet ◽  
Quarkonium Production ◽  
Color Octet Mechanism

The conventional color-singlet model was challenged by the recent data on quarkonium production. Discrepancies in production rates were observed at the Tevatron, at LEP, and in fixed-target experiments. The newly advocated color-octet mechanism provides a plausible solution to the anomalous quarkonium production observed at the Tevatron. The color-octet mechanism should also affect other quarkonium production channels. In this paper we will summarize the studies of quarkonium production in Z0 and ϒ decays.

scholarly journals Saturation in inclusive production beyond leading logarithm accuracy

2016 ◽  
Vol 31 (24) ◽  
pp. 1630039 ◽  
Author(s):  
Anna M. Staśto ◽  
David Zaslavsky
Keyword(s):  
Experimental Data ◽  
Cross Section ◽  
Recent Progress ◽  
Nonlinear Evolution ◽  
High Energy ◽  
Hadron Production ◽  
Suitable Choice ◽  
Inclusive Production ◽  
Leading Order ◽  
Leading Logarithm

We review the recent progress on the calculations on the inclusive forward hadron production within the saturation formalism. After introducing the concept of perturbative parton saturation and nonlinear evolution we discuss the formalism for the forward hadron production at high energy in the leading and next-to-leading order. Numerical results are presented and compared with the experimental data on forward hadron production in [Formula: see text] and [Formula: see text]. We discuss the problem of the negativity of the NLO cross-section at high transverse momenta, study its origin in detail and present possible improvements which include the corrected kinematics and the suitable choice of the rapidity cutoff.

scholarly journals Production of massive color-octet vector bosons at next-to-leading order

2012 ◽  
Vol 85 (5) ◽  
Author(s):  
R. Sekhar Chivukula ◽  
Arsham Farzinnia ◽  
Elizabeth H. Simmons ◽  
Roshan Foadi
Keyword(s):  
Leading Order ◽  
Color Octet ◽  
Vector Bosons

scholarly journals Drell-Yan angular lepton distributions at small x from TMD factorization.

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Ian Balitsky
Keyword(s):  
Transverse Momentum ◽  
Pair Production ◽  
Cross Section ◽  
Z Boson ◽  
Equation Of Motion ◽  
Leading Order ◽  
Small X ◽  
Mulders Function

Abstract The Drell-Yan process is studied in the framework of TMD factorization in the Sudakov region s » Q2 » $$ {q}_{\perp}^2 $$ q ⊥ 2 corresponding to recent LHC experiments with Q2 of order of mass of Z-boson and transverse momentum of DY pair ∼ few tens GeV. The DY hadronic tensors are expressed in terms of quark and quark-gluon TMDs with $$ \frac{1}{Q^2} $$ 1 Q 2 and $$ \frac{1}{N_c^2} $$ 1 N c 2 accuracy. It is demonstrated that in the leading order in Nc the higher-twist quark-quark-gluon TMDs reduce to leading-twist TMDs due to QCD equation of motion. The resulting hadronic tensors depend on two leading-twist TMDs: f1 responsible for total DY cross section, and Boer-Mulders function $$ {h}_1^{\perp } $$ h 1 ⊥ . The corresponding qualitative and semi-quantitative predictions seem to agree with LHC data on five angular coefficients A0− A4 of DY pair production. The remaining three coefficients A5− A7 are determined by quark-quark-gluon TMDs multiplied by extra $$ \frac{1}{N_c} $$ 1 N c so they appear to be relatively small in accordance with LHC results.

scholarly journals An optimal observable for color singlet identification

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Andy Buckley ◽  
Giuseppe Callea ◽  
Andrew Larkoski ◽  
Simone Marzani
Keyword(s):  
Hadronic Decays ◽  
Color Singlet ◽  
Matrix Elements ◽  
Leading Order ◽  
Novel Approach ◽  
Optimal Observable ◽  
Different Color ◽  
Electroweak Boson ◽  
Two Jets ◽  
Sensitive Observables

We present a novel approach to construct a color singlet tagger, i.e.~an observable that is able to discriminate the decay of a color-singlet into two jets from a two-jet background in a different color configuration. We do this by explicitly taking the ratio of the corresponding leading-order matrix elements in the soft limit, thus obtaining an observable that is provably optimal within our approximation. We call this observable the ``jet color ring" and we compare its performance to other color-sensitive observables such as jet pull and dipolarity. We also assess the performance of the jet color ring in simulations by applying it to the case of the hadronic decays of a boosted Higgs boson and of an electroweak boson.

scholarly journals SIMULATION OF Z BOSON pT SPECTRUM AT TEVATRON BY LEADING-ORDER EVENT GENERATORS

2010 ◽  
Vol 25 (36) ◽  
pp. 3047-3059 ◽  
Author(s):  
SHIGERU ODAKA
Keyword(s):  
Transverse Momentum ◽  
Z Boson ◽  
Parton Shower ◽  
Event Generator ◽  
Boson Production ◽  
Proper Solution ◽  
Leading Order

We show that the transverse momentum (pT) spectrum of Z boson production measured at Fermilab Tevatron can be well reproduced by leading-order event generators if Z + 1 jet processes are included with a proper solution for the double-count problem and if the parton shower (PS) branch kinematics are defined appropriately. The choice of the PS evolution variable does not definitely determine the low-pT behavior. Our new event generator employing the limited leading-log (LLL) subtraction and a built-in leading-log PS reproduces the spectrum very well, not only in large pT regions but also at low pT down to pT = 0.

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