scholarly journals Way-out to the gravitino problem in intersecting D-brane Pati–Salam models

2016 ◽  
Vol 31 (19) ◽  
pp. 1650111 ◽  
Author(s):  
Andrea Addazi ◽  
Maxim Yu Khlopov
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
High Energy ◽  
Indirect Detection ◽  
Supersymmetric Particle ◽  
Cosmological Time ◽  
Neutrino Sector ◽  
Very High Energy ◽  
Very High ◽  
Parity Breaking

We discuss the gravitino problem in the context of the exotic see-saw mechanism for neutrinos and leptogenesis, UV completed by intersecting D-branes Pati–Salam models. In the exotic see-saw model, supersymmetry is broken at high scales M[Formula: see text] 109 GeV and this seems in contradiction with gravitino bounds from inflation and baryogenesis. However, if gravitino is the lightest stable supersymmetric particle, it will not decay into other SUSY particles, avoiding the gravitino problem and providing a good cold dark matter (CDM). Gravitini are super heavy dark particles and they can be produced by non-adiabatic expansion during inflation. Intriguingly, from bounds on the correct abundance of dark matter (DM), we also constrain the neutrino sector. We set a limit on the exotic instantonic coupling of [Formula: see text] 10[Formula: see text]–10[Formula: see text]. This also sets constrains on the Calabi–Yau compactifications and on the string scale. This model strongly motivates very high energy DM indirect detection of neutrini and photons of 10[Formula: see text]–10[Formula: see text] GeV: gravitini can decay on them in a cosmological time because of soft R-parity breaking effective operators.

SEARCHING FOR SUPERSYMMETRY AT e+e− SUPERCOLLIDERS

1989 ◽  
Vol 04 (16) ◽  
pp. 4111-4163 ◽  
Author(s):  
HOWARD BAER ◽  
A. BARTL ◽  
DEBRA KARATAS ◽  
W. MAJEROTTO ◽  
XERXES TATA
Keyword(s):  
Large Angle ◽  
High Energy ◽  
Supersymmetric Particle ◽  
Model Parameters ◽  
Ultrahigh Energy ◽  
Mixing Angles ◽  
Missing Transverse Momentum ◽  
Very High Energy ◽  
The Masses ◽  
Very High

We study the signals resulting from the production and subsequent decays of heavy sleptons, sneutrinos and all the charginos [Formula: see text] and neutralinos [Formula: see text] at ultrahigh energy e+e− colliders. In contrast to existing studies that assume that supersymmetric particles directly decay to the lightest supersymmetric particle (taken here to be the lightest neutralino, [Formula: see text]) which then escapes detection, we incorporate realistic decay patterns using the minimal supersymmetry model as a guide for the masses and mixing angles in the gaugino-Higgsino sector. We show that very heavy sleptons and sneutrinos often decay into heavier charginos and neutralinos which themselves often decay into real W and Z0 bosons and lighter [Formula: see text]'s and [Formula: see text]'s. This results in a considerably softer missing transverse momentum [Formula: see text] spectrum than would be expected if sparticles decayed directly to the [Formula: see text] so that [Formula: see text] is not necessarily a viable signature for very heavy sparticles. We show that the optimal signature for supersymmetry in very high energy e+e− collisions depends on the model parameters. Whereas [Formula: see text] is a viable signature for lighter sleptons and sneutrinos (m ~ 0.3 TeV ), the production of very heavy sparticles is signalled by events with two or more large angle W and Z0 bosons and often a very hard electron. We discuss strategies for extracting the SUSY signal and argue that it can be separated from standard model backgrounds over the whole of parameter space.

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 Shell-crossing in a ΛCDM Universe

2020 ◽  
Vol 501 (1) ◽  
pp. L71-L75
Author(s):  
Cornelius Rampf ◽  
Oliver Hahn
Keyword(s):  
Dark Matter ◽  
Perturbation Theory ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Three Dimensional ◽  
Random Initial Data ◽  
Recursion Relations ◽  
Indispensable Tool ◽  
First Time ◽  
Very High

ABSTRACT Perturbation theory is an indispensable tool for studying the cosmic large-scale structure, and establishing its limits is therefore of utmost importance. One crucial limitation of perturbation theory is shell-crossing, which is the instance when cold-dark-matter trajectories intersect for the first time. We investigate Lagrangian perturbation theory (LPT) at very high orders in the vicinity of the first shell-crossing for random initial data in a realistic three-dimensional Universe. For this, we have numerically implemented the all-order recursion relations for the matter trajectories, from which the convergence of the LPT series at shell-crossing is established. Convergence studies performed at large orders reveal the nature of the convergence-limiting singularities. These singularities are not the well-known density singularities at shell-crossing but occur at later times when LPT already ceased to provide physically meaningful results.

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
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