scholarly journals Forward dijets in proton-nucleus collisions at next-to-leading order: the real corrections

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Edmond Iancu ◽  
Yair Mulian
Keyword(s):  
Cross Section ◽  
Soft Gluon ◽  
Effective Theory ◽  
Dglap Evolution ◽  
Leading Order ◽  
Final State ◽  
Dijet Production ◽  
The Real ◽  
First Case ◽  
Subsequent Publication

Abstract Using the CGC effective theory together with the hybrid factorisation, we study forward dijet production in proton-nucleus collisions beyond leading order. In this paper, we compute the “real” next-to-leading order (NLO) corrections, i.e. the radiative corrections associated with a three-parton final state, out of which only two are being measured. To that aim, we start by revisiting our previous results for the three-parton cross-section presented in [1]. After some reshuffling of terms, we deduce new expressions for these results, which not only look considerably simpler, but are also physically more transparent. We also correct several errors in this process. The real NLO corrections to inclusive dijet production are then obtained by integrating out the kinematics of any of the three final partons. We explicitly work out the interesting limits where the unmeasured parton is either a soft gluon, or the product of a collinear splitting. We find the expected results in both limits: the B-JIMWLK evolution of the leading-order dijet cross-section in the first case (soft gluon) and, respectively, the DGLAP evolution of the initial and final states in the second case (collinear splitting). The “virtual” NLO corrections to dijet production will be presented in a subsequent publication.

scholarly journals TMD fragmentation functions at N3LO

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Markus A. Ebert ◽  
Bernhard Mistlberger ◽  
Gherardo Vita
Keyword(s):  
Cross Section ◽  
Production Cross ◽  
Leading Order ◽  
Final State ◽  
Transverse Momentum Dependent ◽  
Final State Radiation ◽  
State Radiation ◽  
Fragmentation Functions ◽  
Initial States ◽  
Independent Calculation

Abstract We compute the unpolarized quark and gluon transverse-momentum dependent fragmentation functions (TMDFFs) at next-to-next-to-next-to-leading order (N3LO) in perturbative QCD. The calculation is based on a relation between the TMDFF and the limit of the semi-inclusive deep inelastic scattering cross section where all final-state radiation becomes collinear to the detected hadron. The required cross section is obtained by analytically continuing our recent computation of the Drell-Yan and Higgs boson production cross section at N3LO expanded around the limit of all final-state radiation becoming collinear to one of the initial states. Our results agree with a recent independent calculation by Luo et al.

scholarly journals Vector meson fragmentation using a model with broken SU(3) at the next-to-leading order

2014 ◽  
Vol 29 (07) ◽  
pp. 1450049 ◽  
Author(s):  
H. Saveetha ◽  
D. Indumathi ◽  
Subhadip Mitra
Keyword(s):  
Vector Meson ◽  
Cross Section ◽  
Evolution Equations ◽  
Light Quark ◽  
Energy Scale ◽  
Dglap Evolution ◽  
Leading Order ◽  
Quark Fragmentation ◽  
Fragmentation Functions ◽  
The Cross

A detailed study of fragmentation of vector mesons at the next-to-leading order (NLO) in QCD is given for e+e- scattering. A model with broken SU(3) symmetry using three input fragmentation functions α(x, Q2), β(x, Q2) and γ(x, Q2) and a strangeness suppression parameter λ describes all the light quark fragmentation functions for the entire vector meson octet. At a starting low energy scale of [Formula: see text] for three light quarks (u, d, s) along with initial parametrization, the fragmentation functions are evolved through DGLAP evolution equations at NLO and the cross-section is calculated. The heavy quarks contribution are added in appropriate thresholds during evolution. The results obtained are fitted at the momentum scale of [Formula: see text] for LEP and SLD data. Good-quality fits are obtained for ρ, K*, ω and ϕ mesons, implying the consistency and efficiency of this model. Strangeness suppression in this model is understood both in terms of ratios of quark fragmentation functions alone as well as in terms of observables; the latter yield a suppression through the K*/ρ multiplicity ratio of about 0.23 while the x dependence of this suppression is also parametrized through the cross-section ratios.

scholarly journals From LO to NLO in the parton Reggeization approach

2018 ◽  
Vol 191 ◽  
pp. 04007 ◽  
Author(s):  
Maxim Nefedov ◽  
Vladimir Saleev
Keyword(s):  
Pair Production ◽  
Cross Section ◽  
Parton Model ◽  
High Energy ◽  
Effective Theory ◽  
Leading Order ◽  
Multi Scale ◽  
Recent Developments

We present recent developments of the parton Reggeization approach (PRA), which is based on high-energy factorization of hard processes in the multi-Regge kinematics and Lipatov’s effective theory of Reggeized gluons and Reggeized quarks. The scheme of calculations in the leading order (LO) of the PRA is discussed. We present important examples of LO PRA applications for cross section calculations of multi-scale hard processes, such as pair production of BB¯-mesons, pair production of photons, and pair production of jets. Also the problem of matching of NLO calculations in PRA with NLO results in the Collinear Parton Model is discussed.

ANALYSIS OF D→ππ BEYOND NAIVE FACTORIZATION

2004 ◽  
Vol 19 (21) ◽  
pp. 1623-1631 ◽  
Author(s):  
XIANG-YAO WU ◽  
XIN-GUO YIN ◽  
DE-BAO CHEN ◽  
YI-QING GUO ◽  
YU ZENG
Keyword(s):  
Calculation Result ◽  
Final State Interaction ◽  
Decay Channel ◽  
Soft Gluon ◽  
Experimental Result ◽  
Leading Order ◽  
Final State ◽  
Sum Rule ◽  
Decay Channels ◽  
Qcd Factorization

We analyze the D→ππ decay channels at the leading order, αs corrections with the QCD factorization and the soft-gluon corrections with the light cone QCD sum rule. Comparing with the experimental result, the calculations of the D0→π+π- and D+→π+π0 decay are much better under the consideration of the contributions of factorization parts, αs corrections and soft-gluon effects. However, the calculation result is one order less than the experimental result in D0→π0π0 decay. It may have large effects of final state interaction in the decay channel.

Central exclusive dijet production at the Tevatron

2014 ◽  
Vol 29 (28) ◽  
pp. 1446002 ◽  
Author(s):  
Konstantin Goulianos
Keyword(s):  
Higgs Boson ◽  
Cross Section ◽  
Transverse Energy ◽  
Boson Production ◽  
Final State ◽  
Dijet Production ◽  
Higgs Boson Production ◽  
The Cross ◽  
Two Jets

We present a review of central exclusive dijet production in [Formula: see text] collisions, where the proton and antiproton emerge intact, and only two jets of transverse energy above a certain threshold are present in the final state. The results are published in two papers by the Collider Detector at Fermilab (CDF) Collaboration, a PRL (2000) and a PRD (2008), based on data collected at [Formula: see text] and 1.96 TeV, respectively, and a D0 Collaboration paper from studies at 1.96 TeV. In all three cases predictions for the cross-section of Higgs boson production are discussed, a process that proceeds via a similar mechanism as dijet production. Roman Pot Spectrometers equipped with tracking detectors are used to measure the outgoing antiproton (CDF and D0) and proton (D0), and special forward detectors are employed to help reduce backgrounds and enrich the data in diffractive and exclusive dijet events.

scholarly journals The role of the threshold variable in soft-gluon resummation of the $$ t\overline{t}h $$ production process

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Melissa van Beekveld ◽  
Wim Beenakker
Keyword(s):  
Cross Section ◽  
Top Quark ◽  
Mellin Transform ◽  
Invariant Mass Distribution ◽  
Hadron Collider ◽  
Soft Gluon ◽  
Deformation Method ◽  
Final State ◽  
Scale Uncertainty

Abstract We study the role of the scale of the threshold variable in soft-gluon threshold resummation. We focus on the computation of the resummed total cross section, the final-state invariant-mass distribution, and transverse-momentum distribution of the Higgs boson when produced in association with a top-anti-top quark pair for the Large Hadron Collider operating at 13 TeV. We show that different choices for the scale of the threshold variable result in differences at next-to-leading power, i.e. contributions that are down by one power of the threshold variable. These contributions are noticeable numerically, although their effect on the resummed observables lies within the scale uncertainty of those observables. The average central results, obtained after combining several central- scale choices, agree remarkably well for different choices of the threshold variable. However, different threshold choices do affect the resulting scale uncertainty. To compute our results, we introduce a novel numerical method that we call the deformation method, which aids the stabilization of the inverse Mellin transform in cases where the analytical Mellin transform of the partonic cross section is unknown. We show that this method leads to a factor of 10 less function evaluations, while gaining a factor of 4 − 5 in numerical precision when compared to the standard method.

scholarly journals Measurement of the inclusive cross-section for the production of jets in association with a Z boson in proton–proton collisions at 8 TeV using the ATLAS detector

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
O. Abdinov ◽  
...  
Keyword(s):  
Cross Section ◽  
Radiation Effects ◽  
Hadron Collider ◽  
Inclusive Cross Section ◽  
Atlas Detector ◽  
Proton Collision ◽  
Leading Order ◽  
Final State ◽  
Proton Proton ◽  
Model Calculations

Abstract The inclusive cross-section for jet production in association with a Z boson decaying into an electron–positron pair is measured as a function of the transverse momentum and the absolute rapidity of jets using 19.9 fb$$^{-1}$$-1 of $$\sqrt{s}=8$$s=8 TeV proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider. The measured $$Z\text { + jets}$$Z+ jets cross-section is unfolded to the particle level. The cross-section is compared with state-of-the-art Standard Model calculations, including the next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations, corrected for non-perturbative and QED radiation effects. The results of the measurements cover final-state jets with transverse momenta up to 1 TeV, and show good agreement with fixed-order calculations.

scholarly journals THEORETICAL STATUS OF THE TOP QUARK CROSS SECTION

2005 ◽  
Vol 20 (14) ◽  
pp. 3171-3173 ◽  
Author(s):  
NIKOLAOS KIDONAKIS ◽  
RAMONA VOGT
Keyword(s):  
Transverse Momentum ◽  
Total Cross Section ◽  
Cross Section ◽  
Top Quark ◽  
Scale Dependence ◽  
Soft Gluon ◽  
Leading Order ◽  
Theoretical Status ◽  
Momentum Distributions ◽  
The Cross

We discuss the most recent calculations of the top quark total cross section and transverse momentum distributions at the Tevatron and the LHC. These calculations include the soft-gluon corrections at next-to-next-to-leading order (NNLO). The soft NNLO corrections stabilize the scale dependence of the cross section.

Who Was the ‘Heroine’ of Freud's First Case History? Problems and Issues in the Identification of Freud's patients

2017 ◽  
Vol 19 (1) ◽  
pp. 7-54 ◽  
Author(s):  
Richard Skues
Keyword(s):  
Case History ◽  
The Real ◽  
Hypnotic Suggestion ◽  
Social Circle ◽  
First Case ◽  
The Face ◽  
Historical Investigation

In 1892–3 Freud published his first substantial case history, which concerned a patient treated by means of hypnotic suggestion. For some years this has been one of the few remaining of Freud's dedicated cases histories where the patient has not been identified. More recently, however, two publications independently arrived at the conclusion that the patient was none other than Freud's wife, Martha. This paper sets out the reasons why this identification should always have been treated with suspicion, even if the real identity was not known. Nevertheless, the paper goes on to offer a more plausible identification from among Freud's known social circle. The second part of the paper questions the circumstances under which the original misidentification could plausibly have been sustained in the face of such glaring evidence to the contrary. It concludes that, among other reasons, recent tendencies in controversies about Freud's trustworthiness have the hazard of leading to unreliable assumptions about Freud's honesty being taken as a basis for sound historical investigation.

Physical Failure Analysis Techniques for Front-End-of-Line Defect Analysis

2016 ◽  
Author(s):  
Dirk Doyle ◽  
Lawrence Benedict ◽  
Fritz Christian Awitan
Keyword(s):  
Cross Section ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Gate Oxide ◽  
Top Down ◽  
New Techniques ◽  
First Case ◽  
Transmission Electron ◽  
Scanning Transmission

Abstract Novel techniques to expose substrate-level defects are presented in this paper. New techniques such as inter-layer dielectric (ILD) thinning, high keV imaging, and XeF2 poly etch overflow are introduced. We describe these techniques as applied to two different defects types at FEOL. In the first case, by using ILD thinning and high keV imaging, coupled with focused ion beam (FIB) cross section and scanning transmission electron microscopy (STEM,) we were able to judge where to sample for TEM from a top down perspective while simultaneously providing the top down images giving both perspectives on the same sample. In the second case we show retention of the poly Si short after removal of CoSi2 formation on poly. Removal of the CoSi2 exposes the poly Si such that we can utilize XeF2 to remove poly without damaging gate oxide to reveal pinhole defects in the gate oxide. Overall, using these techniques have led to 1) increased chances of successfully finding the defects, 2) better characterization of the defects by having a planar view perspective and 3) reduced time in localizing defects compared to performing cross section alone.

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