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.

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.

INELASTIC PHOTOPRODUCTION OF W-BOSON

1998 ◽  
Vol 13 (25) ◽  
pp. 2013-2020
Author(s):  
S. M. KHAIRUL ALAM ◽  
A. M. HARUN AR RASHID
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
W Boson ◽  
Electric Quadrupole ◽  
Parton Model ◽  
High Energy ◽  
Electric Quadrupole Moment ◽  
Photoproduction Process ◽  
Quark Parton Model ◽  
High Energy Collider

We study the WWγ vertex through the process γq→Wq′ where q denotes the quark at a future high energy collider. The differential cross-section for the photoproduction process γq→Wq′ is computed with both anomalous magnetic moment κ and electric quadrupole moment λ for the W-boson. The deep inelastic photoproduction of W± is also calculated in a quark-parton model.

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.

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.

The absorption of high-energy photons in matter

1958 ◽  
Vol 244 (1237) ◽  
pp. 245-258 ◽  
Keyword(s):  
Pair Production ◽  
Cross Section ◽  
Cross Sections ◽  
Born Approximation ◽  
Liquid Scintillation ◽  
Scintillation Counter ◽  
High Energy ◽  
A Value ◽  
Peak Energy ◽  
Better Than

Total absorption cross-sections of hydrogen, carbon, copper, silver, lead and uranium have been measured for photons of mean energy 94 MeV. The method was to measure the transmission through an absorber of photons from the Oxford synchrotron, using a biased liquid scintillation counter to select photons of energy near the peak energy of the machine. The experimental data for hydrogen have been used to deduce a value for the cross-section for pair production in the field of the electron of 4.7 ± 0.4 millibarn. The relative cross-sections for the heavier elements have been determined to better than ± 0.2 %, and confirm the most recent calculations of the correction to the Born approximation in the theory of pair production.

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 Virtual corrections to gg → ZH in the high-energy and large-mt limits

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Joshua Davies ◽  
Go Mishima ◽  
Matthias Steinhauser
Keyword(s):  
Cross Section ◽  
Top Quark ◽  
Form Factors ◽  
Padé Approximants ◽  
High Energy ◽  
Radius Of Convergence ◽  
Leading Order ◽  
Partonic Cross Section ◽  
Pade Approximants ◽  
Energy Expansion

AbstractWe compute the next-to-leading order virtual corrections to the partonic cross-section of the processgg → ZH, in the high-energy and large-mtlimits. We use Padé approximants to increase the radius of convergence of the high-energy expansion in$$ {m}_t^2/s $$mt2/s,$$ {m}_t^2/t $$mt2/tand$$ {m}_t^2/u $$mt2/uand show that precise results can be obtained down to energies which are fairly close to the top quark pair threshold. We present results both for the form factors and the next-to-leading order virtual cross-section.

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