scholarly journals The LPM effect in sequential bremsstrahlung: nearly complete results for QCD

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Peter Arnold ◽  
Tyler Gorda ◽  
Shahin Iqbal
Keyword(s):  
High Energy ◽  
Leading Order ◽  
Energy Limit ◽  
Analytic Investigation ◽  
Very High Energy ◽  
Double Splitting ◽  
Emission Limit ◽  
Coherence Lengths ◽  
Very High ◽  
Virtual Loop

Abstract The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. We continue study of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-emission approximations. Previous work has computed overlap effects for double splitting g → gg → ggg. To make use of those results, one also needs calculations of related virtual loop corrections to single splitting g → gg in order to cancel severe (power-law) infrared (IR) divergences. This paper provides calculations of nearly all such processes involving gluons and discusses how to organize the results to demonstrate the cancellation. In the soft emission limit, our results reproduce the known double-log behavior of earlier authors who worked in leading-log approximation. We also present a first (albeit numerical and not yet analytic) investigation of sub-leading, single IR logarithms. Ultraviolet divergences appearing in our calculations correctly renormalize the coupling αs in the usual LPM result for leading-order g → gg.

Very-High-Energy Limit of Proton-Proton Scattering

1970 ◽  
Vol 2 (3) ◽  
pp. 572-577 ◽  
Author(s):  
A. O. Barut ◽  
W. Plywaski
Keyword(s):  
High Energy ◽  
Proton Scattering ◽  
Energy Limit ◽  
Proton Proton ◽  
High Energy Limit ◽  
Very High Energy ◽  
Very High

scholarly journals QGSJET-III model: physics and preliminary results

2019 ◽  
Vol 208 ◽  
pp. 11001 ◽  
Author(s):  
Sergey Ostapchenko
Keyword(s):  
High Energy ◽  
Previous Model ◽  
Energy Limit ◽  
High Energy Limit ◽  
New Model ◽  
Preliminary Results ◽  
Model Version ◽  
Power Corrections ◽  
Very High Energy ◽  
Very High

We discuss in some detail the physics content of the new model, QGSJET-III-01, focusing on major problems related to the treatment of semihard processes in the very high energy limit. A special attention has been payed to the main improvement, compared to the QGSJET-II model, which is related to a phenomenological treatment of leading power corrections corresponding to final parton rescattering off soft gluons. In particular, this allowed us to use a twice smaller separation scale between the soft and hard parton physics, compared to the previous model version, QGSJET-II-04. Preliminary results obtained with the new model are also presented.

ON MULTIPLICITY DISTRIBUTIONS

1996 ◽  
Vol 11 (34) ◽  
pp. 2681-2692 ◽  
Author(s):  
DING-WEI HUANG
Keyword(s):  
Multiplicity Distribution ◽  
Negative Binomial ◽  
High Energy ◽  
Energy Limit ◽  
High Energy Limit ◽  
Multiple Production ◽  
Very High Energy ◽  
Multiplicity Distributions ◽  
Very High ◽  
New Distribution

We show that four different approaches in multiple production give exactly the same multiplicity distribution. Various experimental data can be well described by this new multiplicity distribution. We compare this new distribution to the negative binomial distribution. The restoration of KNO scaling at the very high energy limit is discussed. A nonvanishing value of the scaled multiplicity distribution Ψ(z) at z=0 is predicted.

Strong interactions at very high energy

1964 ◽  
Vol 82 (1) ◽  
pp. 3-81 ◽  
Author(s):  
Evgenii L. Feinberg ◽  
Dmitrii S. Chernavskii
Keyword(s):  
High Energy ◽  
Strong Interactions ◽  
Very High Energy ◽  
Very High

scholarly journals Focused VHEE (very high energy electron) beams and dose delivery for radiotherapy applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
L. Whitmore ◽  
R. I. Mackay ◽  
M. van Herk ◽  
J. K. Jones ◽  
R. M. Jones
Keyword(s):  
Electron Beams ◽  
Focal Point ◽  
External Beam Radiotherapy ◽  
High Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
Dose Delivery ◽  
Entrance Dose ◽  
Very High Energy ◽  
Very High

AbstractThis paper presents the first demonstration of deeply penetrating dose delivery using focused very high energy electron (VHEE) beams using quadrupole magnets in Monte Carlo simulations. We show that the focal point is readily modified by linearly changing the quadrupole magnet strength only. We also present a weighted sum of focused electron beams to form a spread-out electron peak (SOEP) over a target region. This has a significantly reduced entrance dose compared to a proton-based spread-out Bragg peak (SOBP). Very high energy electron (VHEE) beams are an exciting prospect in external beam radiotherapy. VHEEs are less sensitive to inhomogeneities than proton and photon beams, have a deep dose reach and could potentially be used to deliver FLASH radiotherapy. The dose distributions of unfocused VHEE produce high entrance and exit doses compared to other radiotherapy modalities unless focusing is employed, and in this case the entrance dose is considerably improved over existing radiations. We have investigated both symmetric and asymmetric focusing as well as focusing with a range of beam energies.

Very high energy nucleus-nucleus collisions and multi-chain model

1981 ◽  
Vol 8 (3) ◽  
pp. 205-213 ◽  
Author(s):  
Kisei Kinoshita ◽  
Akira Minaka ◽  
Hiroyuki Sumiyoshi
Keyword(s):  
High Energy ◽  
Chain Model ◽  
Very High Energy ◽  
Very High

scholarly journals Exact quark-mass dependence of the Higgs-photon form factor at three loops in QCD

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Marco Niggetiedt
Keyword(s):  
Form Factor ◽  
Higgs Boson ◽  
Quark Mass ◽  
Variable Mass ◽  
High Energy ◽  
Mass Dependence ◽  
Leading Order ◽  
Energy Limit ◽  
Quark Mass Dependence

Abstract We follow up on our discussion of the exact quark-mass dependence of the Higgs-gluon form factor at three loops in QCD [1] and turn our attention to the closely related Higgs-photon form factor. Similarly to our previous work, we intend to examine the form factor for the decay of a Higgs-boson with variable mass into two photons at the three-loop level in QCD. The set of master integrals is known numerically due to prior work on the Higgs-gluon form factor and is exploited to obtain expansions around the threshold as well as in the high-energy limit. Our results may be utilised to derive the photonic decay rate of the Higgs-boson through next-to-next-to-leading order.

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