A
bstract
We discuss some implications of recent progress in understanding the black hole information paradox for complementarity in de Sitter space. Extending recent work by two of the authors, we ...describe a bulk procedure that allows information expelled through the cosmological horizon to be received by an antipodal observer. Generically, this information transfer takes a scrambling time
t
=
H
−
1
log(
S
dS
). We emphasize that this procedure relies crucially on selection of the Bunch-Davies vacuum state, interpreted as the thermofield double state that maximally entangles two antipodal static patches. The procedure also requires the presence of an (entangled) energy reservoir, created by the collection of Hawking modes from the cosmological horizon. We show how this procedure avoids a cloning paradox and comment on its implications.
A
bstract
We construct novel classes of compact G2 spaces from lifting type IIA flux backgrounds with O6 planes. There exists an extension of IIA Calabi-Yau orientifolds for which some of the D6 ...branes (required to solve the RR tadpole) are dissolved in
F
2
fluxes. The backreaction of these fluxes deforms the Calabi-Yau manifold into a specific class of SU(3)-structure manifolds. The lift to M-theory again defines compact G2 manifolds, which in case of toroidal orbifolds are a twisted generalisation of the Joyce construction. This observation also allows a clear identification of the moduli space of a warped compactification with fluxes. We provide a few explicit examples, of which some can be constructed from T-dualising known IIB orientifolds with fluxes. Finally we discuss supersymmetry breaking in this context and suggest that the purely geometric picture in M-theory could provide a simpler setting to address some of the consistency issues of moduli stabilisation and de Sitter uplifting.
A
bstract
The stabilisation of the dilaton and volume in tree-level flux compactifications leads to model independent and thus very powerful existence and stability criteria for dS solutions. In this ...paper we show that the sizes of cycles wrapped by orientifold planes are scalars whose scalings in the potential are not entirely model independent, but enough to entail strong stability constraints. For all known dS solutions arising from massive IIA supergravity flux compactifications on SU(3)-structure manifolds the tachyons are exactly within the subspace spanned by the dilaton, the total volume and the volumes of the orientifold cycles. We illustrate this in detail for the well-studied case of the
O
6 plane compactification on
. For that example we uncover another novel structure in the tachyon spectrum: the dS solutions have a singular, but supersymmetric, Minkowski limit, in which the tachyon exactly aligns with the sgoldstino.
De Sitter hunting in a classical landscape Danielsson, U.H.; Haque, S.S.; Koerber, P. ...
Fortschritte der Physik,
September 2011, Letnik:
59, Številka:
9
Journal Article
Recenzirano
We elaborate on the construction of de Sitter solutions from IIA orientifolds of SU(3)‐structure manifolds that solve the 10‐dimensional equations of motion at tree‐level in the approximation of ...smeared sources. First we classify geometries that are orbifolds of a group manifold covering space which, upon the proper inclusion of O6 planes, can be described within the framework of 𝒩 = 1 supergravity in 4D. Then we scan systematically for de Sitter solutions, obtained as critical points of an effective 4D potential. Apart from finding many new solutions we emphasize the challenges in constructing explicit classical de Sitter vacua, which have sofar not been met. These challenges are interesting avenues for further research and include finding solutions that are perturbatively stable, satisfy charge and flux quantization, and have genuine localized (versus smeared) orientifold sources. This paper intends to be self‐contained and pedagogical, and thus can serve as a guide to the necessary technical tools required for this line of research. In an appendix we explain how to study flux and charge quantization in the presence of a non‐trivial H‐field using twisted homology.
First measurements of beam backgrounds at SuperKEKB Lewis, P.M.; Jaegle, I.; Nakayama, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2019, Letnik:
914
Journal Article
Recenzirano
Odprti dostop
The high design luminosity of the SuperKEKB electron–positron collider is expected to result in challenging levels of beam-induced backgrounds in the interaction region. Properly simulating and ...mitigating these backgrounds is critical to the success of the Belle II experiment. We report on measurements performed with a suite of dedicated beam background detectors, collectively known as BEAST II, during the so-called Phase 1 commissioning run of SuperKEKB in 2016, which involved operation of both the high energy ring (HER) of 7 GeV electrons as well as the low energy ring (LER) of 4 GeV positrons. We describe the BEAST II detector systems, the simulation of beam backgrounds, and the measurements performed. The measurements include standard ones of dose rates versus accelerator conditions, and more novel investigations, such as bunch-by-bunch measurements of injection backgrounds and measurements sensitive to the energy spectrum and angular distribution of fast neutrons. We observe beam–gas, Touschek, beam–dust, and injection backgrounds. As there is no final focus of the beams in Phase 1, we do not observe significant synchrotron radiation, as expected. Measured LER beam–gas backgrounds and Touschek backgrounds in both rings are slightly elevated, on average three times larger than the levels predicted by simulation. HER beam–gas backgrounds are on average two orders of magnitude larger than predicted. Systematic uncertainties and channel-to-channel variations are large, so that these excesses constitute only 1–2 sigma level effects. Neutron background rates are higher than predicted and should be studied further. We will measure the remaining beam background processes, due to colliding beams, in the imminent commissioning Phase 2. These backgrounds are expected to be the most critical for Belle II, to the point of necessitating replacement of detector components during the Phase 3 (full-luminosity) operation of SuperKEB.
An HPLC/MS/MS method has been developed for the characterization and quantification of ginsenosides contained in extracts of the root of Panax ginseng (Korean ginsengs) and Panax quinquefolius L. ...(American ginsengs). The M + H+ and M + Na+ ions were observed for ginsenoside standards (Rb1, Rb2, Rc, Rd, Re, Rf, Rg1) and four different ginseng extracts. The glycosidic linkages, the core, and the attached sugar(s) of the ginsenosides can be determined from the collision-induced dissociation spectra from the protonated molecules. The relative distribution of these ginsenosides in each extract of American or Korean ginseng was established.
We report new measurements of the production cross sections of pairs of charged pions and kaons as a function of their fractional energies using various fractional-energy definitions. Two different ...fractional-energy definitions were used and compared to the conventional fractional-energy definition reported previously. The new variables aim at either identifying dihadron cross sections in terms of single-hadron fragmentation functions, or to provide a means of characterizing the transverse momentum created in the fragmentation process. The results were obtained applying the updated initial-state radiation correction used in other recent Belle publications on light-hadron production cross sections. In addition, production cross sections of single charged pions, kaons, and protons were also updated using this initial-state radiation correction. The cross sections are obtained from a 558 fb-1 data sample collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
The highly reactive and unstable exothermal features of methyl ethyl ketone peroxide (MEKPO) have led to a large number of thermal explosions and runaway reaction accidents in the manufacturing ...process. To evaluate the self-accelerating decomposition temperature (SADT) of MEKPO in various storage vessels, we used differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2). The thermokinetic parameters were, in turn, used to calculate the SADT from theoretical equations based on the Semenov model.
This study aimed at the SADT prediction value of various storage vessels in Taiwan compared with the UN 25 kg package and UN 0.51 L Dewar vessel. An important index, such as SADT, temperature of no return (
T
NR
) and adiabatic time maximum rate (TMR
ad
), was necessary and useful to ensure safe storage or transportation for self-reactive substances in the process industries.
TOWARD REALISTIC INTERSECTING D-BRANE MODELS Blumenhagen, Ralph; Cvetič, Mirjam; Langacker, Paul ...
Annual review of nuclear and particle science,
12/2005, Letnik:
55, Številka:
1
Journal Article
Recenzirano
Odprti dostop
▪ Abstract We provide a pedagogical introduction to a recently studied class of phenomenologically interesting string models known as Intersecting D-Brane Models. The gauge fields of the Standard ...Model are localized on D-branes wrapping certain compact cycles on an underlying geometry, whose intersections can give rise to chiral fermions. We address the basic issues and also provide an overview of the recent activity in this field. This article is intended to serve non-experts with explanations of the fundamental aspects of string phenomenology and also to provide some orientation for both experts and non-experts in this active field.
We present the study of a fuzzy clustering algorithm for the Belle II electromagnetic calorimeter using Graph Neural Networks. We use a realistic detector simulation including simulated beam ...backgrounds and focus on the reconstruction of both isolated and overlapping photons. We find significant improvements of the energy resolution compared to the currently used reconstruction algorithm for both isolated and overlapping photons of more than 30% for photons with energies
E
γ
<
0.5
Ge
V
and high levels of beam backgrounds. Overall, the GNN reconstruction improves the resolution and reduces the tails of the reconstructed energy distribution and therefore is a promising option for the upcoming high luminosity running of Belle II.
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