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Jochen Bartels

Publications and source records attributed to Jochen Bartels.

At least 19 recordsLinked to original sources
arXiv2024

Emergent symmetries at criticality in multi field RFT/DP

We study multifield extensions of Reggeon Field Theory (also equivalent to Directed Percolation model) at criticality in the perturbative epsilon-expansion below the upper critical dimension Dc=4 at one loop, for the special case when all fields have the same scale (anomalous) dimensions. Analyzing all the fixed points of the renormalization group flow for N=2 flavors and some for N=3, we find scale invariant solutions which are characterized by specific emergent global symmetries of the interacting potential. We also study two infinite families as a function of N having Z_N and S_{N+1} symmetries.

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arXiv2020

Analytic structure of the 8-point scattering amplitude in multi-Regge kinematics in N=4 SYM: conformal Regge pole and Regge cut contributions

Continuing our investigations of the analytic structure of the 2->n scattering amplitudes in the planar limit of N=4 SYM in multi-Regge kinematics we compute, in all kinematic regions, the Regge cut contributions of the 2->6 process in leading order. Compared to previous studies of the 2->4 and the 2->5 processes we encounter two new features: the 3-reggon cut and the product of two 2-reggeon cut contributions.

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arXiv2019

The Odderon in QCD with running coupling

Starting from the leading Odderon solution of the three gluon system in perturbative QCD we introduce, as a first step towards the transition to the nonperturbative region, an infrared cutoff and use the running QCD coupling constant. In our numerical analysis we find that the fixed cut solution with intercept one persists, hinting at a physical Odderon with intercept one and a small t-slope.

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arXiv2016

On the energy spectrum of the electroweak Pomeron

In this paper we study the high energy behaviour of Electroweak Standard Model for a nonzero Weinberg angle $θ_{W}$. We evaluate the spectrum of the electroweak pomeron and demonstrate that the leading intercept is given by $α_{\rm e.w.}4 \ln 2$ and does not depend on the mixing angle $θ_{W}$. Due to its very small numerical value, we conclude that the high energy behaviour of electroweak theory cannot be discussed without including the QCD Pomeron which, at sufficiently large energies, will dominate.

hep-ph↗
arXiv2016

Could reggeon field theory be an effective theory for QCD in the Regge limit?

In this paper we investigate the possibility whether, in the extreme limit of high energies and large transverse distances, reggeon field theory might serve as an effective theory of high energy scattering for strong interactions. We analyse the functional renormalization group equations (flow equations) of reggeon field theory and search for fixed points in the space of (local) reggeon field theories. We study in complementary ways the candidate for the scaling solution, investigate its main properties and briefly discuss possible physical interpretations.

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arXiv2014

Analytic structure of the $n=7$ scattering amplitude in $\mathcal{N}=4$ SYM theory at multi-Regge kinematics: Conformal Regge pole contribution

We investigate the analytic structure of the $2\to5$ scattering amplitude in the planar limit of $\mathcal{N}=4$ SYM in multi-Regge kinematics in all physical regions. We demonstrate the close connection between Regge pole and Regge cut contributions: in a selected class of kinematic regions (Mandelstam regions) the usual factorizing Regge pole formula develops unphysical singularities which have to be absorbed and compensated by Regge cut contributions. This leads, in the corrections to the BDS formula, to conformal invariant 'renormalized' Regge pole expressions in the remainder function. We compute these renormalized Regge poles for the $2\to5$ scattering amplitude.

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arXiv2012

Double-logarithms in Einstein-Hilbert gravity and supergravity

We study the interplay between graviton reggeization and double-logarithmic in energy contributions to four-graviton scattering in theories with and without supersymmetry. Predictions to all orders in the gravitational coupling are given for these double-logarithms. As the number of supersymmetries grows these terms generate a convergent behaviour for the amplitudes at very high energies. At two-loop level, we find agreement with previous exact results for N=8 supergravity and with those of Boucher-Veronneau and Dixon, who studied the N=4,5,6 supergravities using a conjectured double-copy structure of gravity.

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arXiv2009

High Energy Behavior of a Six-Point R-Current Correlator in N=4 Supersymmetric Yang-Mills Theory

We study the high energy limit of a six-point R-current correlator in N=4 supersymmetric Yang-Mills theory for finite N_c. We make use of the framework of perturbative resummation of large logarithms of the energy. More specifically, we apply the (extended) generalized leading logarithmic approximation. We find that the same conformally invariant two-to-four gluon vertex occurs as in non-supersymmetric Yang-Mills theory. As a new feature we find a direct coupling of the four-gluon t-channel state to the R-current impact factor.

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arXiv2009

Twist expansion of the nucleon structure functions, F2 and FL, in the DGLAP improved saturation model

Higher twist effects in the deeply inelastic scattering are studied. We start with a short review of the theoretical results on higher twists in QCD. Within the saturation model we perform a twist analysis of the nucleon structure functions FT and FL at small value of the Bjorken variable x. The parameters of the model are fitted to the HERA F2 data, and we derive a prediction for the longitudinal structure function FL. We conclude that for FL the higher twist corrections are sizable whereas for F2 = FT + FL there is a nearly complete cancellation of twist-4 corrections in FT and FL. We discuss a few consequences for future LHC measurements.

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arXiv2009

The topology of the triple Pomeron vertex in N=4 SYM

We investigate, within N=4 SYM, the high energy behavior in the triple Regge limit of a six point correlator of R-currents. Using the leading logarithmic approximation, we sum all diagrams whose color lines fit onto the surface of a sphere. We find three distinct classes of graphs, and one of them contains the triple Pomeron vertex known from QCD. We present results which, within the AdS/CFT correspondence, can be compared with scattering amplitudes in the dual string theory.

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arXiv2008

What HERA may provide ?

More than 100 people participated in a discussion session at the DIS08 workshop on the topic What HERA may provide. A summary of the discussion with a structured outlook and list of desirable measurements and theory calculations is given.

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arXiv2007

A momentum Space Analysis of the Triple Pomeron Vertex in pQCD

We study properties of the momentum space Triple Pomeron Vertex in perturbative QCD. Particular attention is given to the collinear limit where transverse momenta on one side of the vertex are much larger than on the other side. We also comment on the kernels in nonlinear evolution equations.

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arXiv2006

The Pomeranchuk Singularity and Vector Boson Reggeization in Electroweak Theory

We investigate the high energy behaviour of vector boson scattering in the electroweak sector of the standard model. In analogy with the BFKL analysis in QCD we compute production amplitudes in the multi-Regge limit and derive, for the vacuum exchange channel, the integral equation for vector particle scattering. We also derive and solve the bootstrap equations for the isospin-1 exchange channel, both for the reggeizing charged and non-reggeizing neutral vector bosons.

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arXiv2004

$γ^* γ^*$ Scattering via Secondary Reggeon Exchange in QCD

We summarize the results on the high energy behavior of quark-antiquark exchange in $γ^* γ^*$ elastic scattering. The ladder diagrams, summed in the double logarithmic approximation, provide a perturbative QCD model for secondary reggeon exchange.

hep-ph↗
arXiv2000

Effect of the Charm Quark Mass on the BFKL gamma^* gamma^* Total Cross Section at LEP

We perform a numerical study of various improvements of the LO BFKL prediction for the gamma^* gamma^* total cross section in the kinematical region of the L3 detector at LEP. In particular, we study the effects of a massive charm quark and of different photon polarizations. The variation of the BFKL prediction under changes of alpha_s is investigated.

hep-ph↗
arXiv1999

Unitarity Corrections in High Energy QCD

The high energy limit of QCD is investigated in the generalized leading logarithmic approximation. We study unitarity corrections to the BFKL Pomeron containing t-channel states with up to six gluons. Special attention is given to the field theory structure of the corresponding multi-gluon amplitudes. We discuss the transition from two to six gluons in the t-channel.

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