scholarly journals Forward particle production in proton-nucleus collisions at next-to-leading order

2018 ◽  
Vol 192 ◽  
pp. 00014
Author(s):  
D.N. Triantafyllopoulos
Keyword(s):  
Cross Section ◽  
Particle Production ◽  
Eikonal Approximation ◽  
High Energy ◽  
Fine Tuning ◽  
Color Glass ◽  
Leading Order ◽  
Energy Evolution ◽  
The Impact ◽  
Correct Size

We consider the next-to-leading order (NLO) calculation of single inclusive particle production at forward rapidities in proton-nucleus collisions and in the framework of the Color Glass Condensate (CGC). We focus on the quark channel and the corrections associated with the impact factor. In the first step of the evolution the kinematics of the emitted gluon is kept exactly (and not in the eikonal approximation), but such a treatment which includes NLO corrections is not explicitly separated from the high energy evolution. Thus, in this newly established “factorization scheme”, there is no “rapidity subtraction”. The latter suffers from fine tuning issues and eventually leads to an unphysical (negative) cross section. On the contrary, our reorganization of the perturbation theory leads by definition to a well-defined cross section and the numerical evaluation of the NLO correction is shown to have the correct size.

scholarly journals On the W&Y interpretation of high-energy Drell-Yan measurements

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Riccardo Torre ◽  
Lorenzo Ricci ◽  
Andrea Wulzer
Keyword(s):  
Monte Carlo ◽  
Differential Cross Section ◽  
Monte Carlo Simulations ◽  
Cross Section ◽  
Differential Cross ◽  
High Energy ◽  
New Physics ◽  
Leading Order ◽  
Theoretical Predictions ◽  
The Impact

Abstract High-energy neutral and charged Drell-Yan differential cross-section measurements are powerful probes of quark-lepton contact interactions that produce growing-with-energy effects. This paper provides theoretical predictions of the new physics effects at the Next-to-Leading order in QCD and including one-loop EW corrections at the single-logarithm accuracy. The predictions are obtained from SM Monte Carlo simulations through analytic reweighting. This eliminates the need of performing a scan on the new physics parameter space, enabling the global exploration of all the relevant interactions. Furthermore, our strategy produces consistently showered events to be employed for a direct comparison of the new physics predictions with the data, or to validate the unfolding procedure than underlies the cross-section measurements. Two particularly relevant interactions, associated with the W and Y parameters of EW precision tests, are selected for illustration. Projections are presented for the sensitivity of the LHC and of the HL-LHC measurements. The impact on the sensitivity of several sources of uncertainties is quantified.

scholarly journals Charged current Drell-Yan production at N3LO

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Claude Duhr ◽  
Falko Dulat ◽  
Bernhard Mistlberger
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross Section ◽  
Production Cross ◽  
Hadron Collider ◽  
Charge Asymmetry ◽  
Charged Current ◽  
Leading Order ◽  
Neutrino Pair ◽  
The Impact

Abstract We present the production cross section for a lepton-neutrino pair at the Large Hadron Collider computed at next-to-next-to-next-to-leading order (N3LO) in QCD perturbation theory. We compute the partonic coefficient functions of a virtual W± boson at this order. We then use these analytic functions to study the progression of the perturbative series in different observables. In particular, we investigate the impact of the newly obtained corrections on the inclusive production cross section of W± bosons, as well as on the ratios of the production cross sections for W+, W− and/or a virtual photon. Finally, we present N3LO predictions for the charge asymmetry at the LHC.

scholarly journals TACHYON DYNAMICS OF THE BLACK DISC LIMIT IN THE HARD SMALL x PROCESSES IN QCD

2006 ◽  
Vol 21 (07) ◽  
pp. 549-558 ◽  
Author(s):  
B. BLOK ◽  
L. FRANKFURT
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
High Energy ◽  
Black Disk ◽  
Black Disc ◽  
Energy Behavior ◽  
Small X ◽  
The Cross ◽  
The Impact ◽  
Black Disc Limit

We investigate the effective field theory (EFT) which gives the approximate description of the scattering of two hard small dipoles in the small x processes in QCD near the black disc limit (BDL). We argue that the perturbative QCD approaches predict the existence of tachyon and visualize it in the approximation where α′P=0. We demonstrate that the high energy behavior of the cross-section depends strongly on the diffusion law in the impact parameter plane. On the other hand, almost threshold behavior of the cross section of the hard processes and multiplicities, i.e. fast increase of cross sections (color inflation), melting of ladders into color network and softening of the longitudinal distributions of hadrons are qualitatively insensitive to the value of diffusion in the impact parameter space. We evaluate α′P near the black disk limit and find significant α′P as the consequence of the probability conservation.

INSTANTON-INDUCED CROSS-SECTION AT HIGH ENERGIES: LEADING ORDER AND BEYOND

1990 ◽  
Vol 05 (24) ◽  
pp. 1983-1991 ◽  
Author(s):  
S. YU. KHLEBNIKOV ◽  
V. A. RUBAKOV ◽  
P. G. TINYAKOV
Keyword(s):  
Total Cross Section ◽  
Explicit Form ◽  
Cross Section ◽  
High Energy ◽  
Electroweak Theory ◽  
Leading Order ◽  
Instanton Action ◽  
High Energies ◽  
High Energy Collisions ◽  
The One

We study the total cross-section of high energy collisions in the one-instanton sector of purely bosonic theories with instantons. We find that in the limit g2 → 0, E/E sph = fixed , the leading behavior of the total cross-section is σ lot ~ exp [1/g2(−2S0 + F(E/E sph ))], where S0 is the instanton action. In the electroweak theory at E/E sph ≪ 1, the function F(E/E sph ) is determined by the gauge boson part of the instanton configuration and its explicit form is found.

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.

THE IMPACT OF LO, NLO AND NNLO FOR THE HIGGS SEARCHING AT $\sqrt{s} = 7$ TeV OF LHC

2010 ◽  
Vol 25 (36) ◽  
pp. 3027-3031
Author(s):  
JIAN WANG ◽  
GUOMING CHEN ◽  
WEIMIN WU
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Higgs Mass ◽  
Monte Carlo Generator ◽  
Final States ◽  
Leading Order ◽  
Analysis Process ◽  
Signal Rate ◽  
Monte Carlo Studies ◽  
The Impact

Most of current Monte Carlo studies on the Higgs searching are based on LO, or NLO calculation. However, in recent years, the next-to-next-to-leading order (NNLO) corrections have been computed for some physics process, and found that the cross section increases the kinematics changes. As the results, the analysis results could be impacted by these high order QCD corrections. We use standard Monte Carlo generator for LO, as well as MC@NLO for NLO and ResBos for NNLO at 7 TeV of LHC to evaluate this impact for physics channel of the Higgs, mass at 165 GeV, to WW, then W decay to lepton and neutrino as the final states. We found the signal rate could be effected by ratio of 1:2.6:3.4 for LO, NLO and NNLO using the same standard H→WW→lνlν searching analysis process.6

scholarly journals On the impact of non-factorisable corrections in VBF single and double Higgs production

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Frédéric A. Dreyer ◽  
Alexander Karlberg ◽  
Lorenzo Tancredi
Keyword(s):  
Vector Boson ◽  
Relative Size ◽  
Eikonal Approximation ◽  
Higgs Production ◽  
Leading Order ◽  
Scale Uncertainty ◽  
Before And After ◽  
Depth Study ◽  
Uncertainty Band ◽  
The Impact

Abstract We study the non-factorisable QCD corrections, computed in the eikonal approximation, to Vector-Boson Fusion single and double Higgs production and show the combined factorisable and non-factorisable corrections for both processes at $$ \mathcal{O}\left({\alpha}_s^2\right) $$ O α s 2 . We investigate the validity of the eikonal approximation with and without selection cuts, and carry out an in-depth study of the relative size of the non-factorisable next-to-next-to-leading order corrections compared to the factorisable ones. In the case of single Higgs production, after selection cuts are applied, the non-factorisable corrections are found to be mostly contained within the factorisable scale uncertainty bands. When no cuts are applied, instead, the non-factorisable corrections are slightly outside the scale uncertainty band. Interestingly, for double Higgs production, we find that both before and after applying cuts, non-factorisable corrections are enhanced compared to the single Higgs case. We trace this enhancement to the existence of delicate cancellations between the various leading-order Feynman diagrams, which are partly spoiled by radiative corrections. All contributions studied here have been implemented in proVBFH v1.2.0 and proVBFHH v1.1.0.

PROCESSES WITH LARGE IMPACT PARAMETERS AT COLLIDING BEAMS

1992 ◽  
Vol 07 (20) ◽  
pp. 4707-4745 ◽  
Author(s):  
G.L. KOTKIN ◽  
V.G. SERBO ◽  
A. SCHILLER
Keyword(s):  
Cross Section ◽  
Particle Production ◽  
Single Photon ◽  
High Energy ◽  
Distribution Functions ◽  
Large Impact ◽  
Beam Polarization ◽  
Quantum Distribution ◽  
Impact Parameters ◽  
The Cross

At the collider VEPP-4 a remarkable deviation of the measured bremsstrahlung photons from the standard calculation method has been measured in the reaction e+e−→e+e−γ. The decreasing number of photons is explained by the fact that large impact parameters give the essential contributions to the cross section. These parameters are by several orders of magnitude larger than the transverse beam sizes. In that case the standard definitions of “cross section” and “number of events” are invalid. Similar effects are expected for the single photon bremsstrahlung and the e+e− pair production at existing and planned high energy e±e−, ep and eγ colliders. A calculation scheme for particle production in the interaction of two bunches, which allows one to take into account these effects quantitatively, is presented. In this scheme the colliding bunches are represented as wave packets, and quantum distribution functions are used. The modified definitions of the cross section and the number of events contain the features of “nonlocality” and “interference”. Reasonable approximations which can be easily used are discussed. The results are applied to analyze the influence of the finite beam sizes on reactions which have been proposed for measuring the luminosity and the beam polarization at the colliders LEP and HERA.

scholarly journals Particle Production at High Energy: DGLAP, BFKL and Beyond

Universe ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 64 ◽  
Author(s):  
Jamal Jalilian-Marian
Keyword(s):  
Evolution Equation ◽  
Particle Production ◽  
Evolution Equations ◽  
High Energy ◽  
Color Glass ◽  
Collinear Factorization ◽  
Perturbative Quantum Chromodynamics ◽  
Nuclear Collisions ◽  
Perturbative Quantum ◽  
Regge Limit

Particle production in high energy hadronic/nuclear collisions in the Bjorken limit Q 2 , s → ∞ can be described in the collinear factorization framework of perturbative Quantum ChromoDynamics (QCD). On the other hand in the Regge limit, at fixed and not too high Q 2 with s → ∞ , a k ⊥ factorization approach (or a generalization of it) is the appropriate framework. A new effective action approach to QCD in the Regge limit, known as the Color Glass Condensate (CGC) formalism, has been developed which allows one to investigate particle production in high energy collisions in the kinematics where collinear factorization breaks down. Here we give a brief overview of particle production in CGC framework and the evolution equation which governs energy dependence of the observables in this formalism. We show that the new evolution equation reduces to previously known evolution equations in the appropriate limits.

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