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T. Muller

Publications and source records attributed to T. Muller.

14 recordsLinked to original sources
arXiv2023

Duality of O(N) and Sp(N) random tensor models: tensors with symmetries

In a recent series of papers, a duality between orthogonal and symplectic random tensor models has been proven, first for quartic models and then for models with interactions of arbitrary order. However, the tensor models considered so far in the literature had no symmetry under permutation of the indices. In this paper, we generalize these results for tensors models with interactions of arbitrary order which further have non-trivial symmetry under the permutation of the indices. Totally symmetric and anti-symmetric tensors are thus treated as a particular case of our result.

math-ph↗
arXiv2023

Double scaling limit of the prismatic tensor model

In S. Giombi, I. Klebanov, F. Popov, S. Prakash and G. Tarnopolsky, {\it Phys. Rev.} {\bf D} 98 (2018) 10, 105005, a prismatic tensor model was introduced. We study here the diagrammatics and the double scaling limit of this model, using the intermediate field method. We explicitly exhibit the next-to-leading order Feynman graphs in the $1/N$ expansion. Using appropriate combinatorial tools, we further study the general term of the $1/N$ expansion and we compute the $2-$point function in the double scaling limit.

hep-th↗
arXiv2016

Supernova Progenitors, Their Variability, and the Type IIP Supernova ASASSN-16fq in M66

We identify a pre-explosion counterpart to the nearby Type IIP supernova ASASSN-16fq (SN 2016cok) in archival Hubble Space Telescope (HST) data. The source appears to be a blend of several stars that prevents obtaining accurate photometry. However, with reasonable assumptions about the stellar temperature and extinction, the progenitor almost certainly had an initial mass M<17Msun, and was most likely in the mass range 8-12Msun. Observations once ASASSN-16fq has faded will have no difficulty accurately determining the properties of the progenitor. In 8 years of Large Binocular Telescope (LBT) data, no significant progenitor variability is detected to RMS limits of roughly 0.03 mag. Of the six nearby SN with constraints on low level variability, SN 1987A, SN 1993J, SN 2008cn, SN 2011dh, SN 2013ej and ASASSN-16fq, only the slowly fading progenitor of SN 2011dh showed clear evidence of variability. Excluding SN 1987A, the 90% confidence limit implied by these sources on the number of outbursts over the last decade before the SN that last longer than 0.1 years (FWHM) and are brighter than M_R<-8 mag is approximately N<3. Our continuing LBT monitoring program will steadily improve constraints on pre-SN progenitor variability at amplitudes far lower than achievable by SN surveys.

astro-ph.SR↗
arXiv2012

The effect of the high-pass filter data reduction technique on the Herschel PACS Photometer PSF and noise

We investigate the effect of the "high-pass filter" data reduction technique on the Herschel PACS PSF and noise of the PACS maps at the 70, 100 and 160 um bands and in medium and fast scan speeds. This branch of the PACS Photometer pipeline is the most used for cosmological observations and for point-source observations.The calibration of the flux loss due to the median removal applied by the PACS pipeline (high-pass filter) is done via dedicated simulations obtained by "polluting" real PACS timelines with fake sources at different flux levels. The effect of the data reduction parameter settings on the final map noise is done by using selected observations of blank fields with high data redundancy. We show that the running median removal can cause significant flux losses at any flux level. We analyse the advantages and disadvantages of several masking strategies and suggest that a mask based on putting circular patches on prior positions is the best solution to reduce the amount of flux loss. We provide a calibration of the point-source flux loss for several masking strategies in a large range of data reduction parameters, and as a function of the source flux. We also show that, for stacking analysis, the impact of the high-pass filtering effect is to reduce significantly the clustering effect. The analysis of the global noise and noise components of the PACS maps shows that the dominant parameter in determining the final noise is the high-pass filter width. We also provide simple fitting functions to build the error map from the coverage map and to estimate the cross-correlation correction factor in a representative portion of the data reduction parameter space.

astro-ph.IM↗
arXiv2010

H-ATLAS: PACS imaging for the Science Demonstration Phase

We describe the reduction of data taken with the PACS instrument on board the Herschel Space Observatory in the Science Demonstration Phase of the Herschel-ATLAS (H-ATLAS) survey, specifically data obtained for a 4x4-deg^2 region using Herschel's fast-scan (60 arcsec/s) parallel mode. We describe in detail a pipeline for data reduction using customised procedures within HIPE from data retrieval to the production of science-quality images. We found that the standard procedure for removing Cosmic-Ray glitches also removed parts of bright sources and so implemented an effective two-stage process to minimise these problems. The pronounced 1/f noise is removed from the timelines using 3.4- and 2.5-arcmin boxcar high-pass filters at 100 and 160-um. Empirical measurements of the point-spread function (PSF) are used to determine the encircled energy fraction as a function of aperture size. For the 100- and 160-um bands, the effective PSFs are ~9 and ~13 arcsec (FWHM), and the 90-per-cent encircled energy radii are 13 and 18 arcsec. Astrometric accuracy is good to ~<2 arcsec. The noise in the final maps is correlated between neighbouring pixels and rather higher than advertised prior to launch. For a pair of cross-scans, the 5-sigma point-source sensitivities are 125-165 mJy for 9-13-arcsec radius apertures at 100-um and 150-240 mJy for 13-18-arcsec radius apertures at 160-um.

astro-ph.IM↗
arXiv2009

Low temperature optical characterization of near infrared single photon emitters in nanodiamonds

In this paper, we study the optical properties of single defects emitting in the near infrared in nanodiamonds at liquid helium temperature. The nanodiamonds are synthesized using a microwave chemical vapor deposition method followed by nickel implantation and annealing. We show that single defects exhibit several striking features at cryogenic temperature: the photoluminescence is strongly concentrated into a sharp zero-phonon line in the near infrared, the radiative lifetime is in the nanosecond range and the emission is perfectly linearly polarized. The spectral stability of the defects is then investigated. An optical resonance linewidth of 4 GHz is measured using resonant excitation on the zero-phonon line. Although Fourier-transform limited emission is not achieved, our results show that it might be possible to use consecutive photons emitted in the near infrared by single defects in diamond nanocrystals to perform two photon interference experiments, which are at the heart of linear quantum computing protocols.

quant-ph↗
arXiv2009

The Herschel ATLAS

The Herschel ATLAS is the largest open-time key project that will be carried out on the Herschel Space Observatory. It will survey 510 square degrees of the extragalactic sky, four times larger than all the other Herschel surveys combined, in five far-infrared and submillimetre bands. We describe the survey, the complementary multi-wavelength datasets that will be combined with the Herschel data, and the six major science programmes we are undertaking. Using new models based on a previous submillimetre survey of galaxies, we present predictions of the properties of the ATLAS sources in other wavebands.

astro-ph.CO↗
arXiv2006

I.C.E.: a Transportable Atomic Inertial Sensor for Test in Microgravity

We present our the construction of an atom interferometer for inertial sensing in microgravity, as part of the I.C.E. (\textit{Interférométrie Cohérente pour l'Espace}) collaboration. On-board laser systems have been developed based on fibre-optic components, which are insensitive to mechanical vibrations and acoustic noise, have sub-MHz linewidth, and remain frequency stabilised for weeks at a time. A compact, transportable vacuum system has been built, and used for laser cooling and magneto-optical trapping. We will use a mixture of quantum degenerate gases, bosonic $^{87}$Rb and fermionic $^{40}$K, in order to find the optimal conditions for precision and sensitivity of inertial measurements. Microgravity will be realised in parabolic flights lasting up to 20s in an Airbus. We show that the factors limiting the sensitivity of a long-interrogation-time atomic inertial sensor are the phase noise in reference frequency generation for Raman-pulse atomic beam-splitters and acceleration fluctuations during free fall.

cond-mat.other↗
arXiv2004

Experimental investigation of early-time diffusion in the quantum kicked rotor using a Bose-Einstein condensate

We report the experimental observation of resonances in the early-time momentum diffusion rates for the atom-optical delta-kicked rotor. In this work a Bose-Einstein condensate provides a source of ultra-cold atoms with an ultra-narow initial momentum distribution, which is then subjected to periodic pulses (or "kicks") using an intense far-detuned optical standing wave. A quantum resonance occurs when the momentum eigenstates accumulate the same phase between kicks leading to ballistic energy growth. Conversely, an anti-resonance is observed when the phase accumulated from successive kicks cancels and the system returns to its initial state. Our experimental results are compared with theoretical predictions.

cond-mat.soft↗
arXiv2002

Prospects for Higgs Boson Searches in the Channel WH -> lnbb

We present a method how to detect the WH -> lnbb in the high luminosity LHC environment with the CMS detector. This study is performed with fast detector response simulation including high luminosity event pile up. The main aspects of reconstruction are pile up jet rejection, identification of b-jets and improvement of Higgs mass resolution. The detection potential in the SM for m(H) < 130 GeV and in the MSSM is only encouraging for high integrated luminosity. Nevertheless it is possible to extract important Higgs parameters which are useful to elucidate the nature of the Higgs sector. In combination with other channels, this channel provides valuable information on Higgs boson couplings.

hep-ph↗
arXiv2001

Searching for Higgs Bosons in Association with Top Quark Pairs in the H -> bb Decay Mode

Search for the Higgs Boson is one of the prime goals of the LHC. Higgs bosons lighter than 130 GeV decay mainly to a b-quark pair. While the detection of a directly produced Higgs boson in the bb channel is impossible because of the huge QCD background, the channel ttH -> lnqqbbbb is very promising in the Standard Model and the MSSM. We discuss an event reconstruction and selection method based on likelihood functions. The CMS detector response is performed with parametrisations obtained from detailed simulations. Various physics and detector performance scenarios are investigated and the results are presented. It turns out that excellent b-tagging performance and good mass resolution are essential for this channel.

hep-ph↗
arXiv1999

Stability and diffusion of surface clusters

Using kinetic Monte Carlo simulations and a bond-counting ansatz, thermal stability and diffusion of an adatom island on a crystal surface are studied. At low temperatures, the diffusion constant $D$ is found to decrease for a wide range of island sizes like $D \propto N^{-α}$, where $α$ is close to one, $N$ being the number of adatoms in the cluster. By heating up the surface, the system undergoes a phase transition above which the island disappears. Characteristics of that transition are discussed.

cond-mat↗
arXiv1998

Search for muonic decays of the antiproton at the Fermilab Antiproton Accumulator

A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on six antiproton decay modes which contain a final-state muon. At the 90% C.L. we find that tau/B(mu gamma) > 5.0 x 10^4 yr, tau/B(mu pi0) > 4.8 x 10^4 yr, tau/B(mu eta) > 7.9 x 10^3 yr, tau/B(mu gamma gamma) > 2.3 x 10^4 yr, tau/B(mu K0S > 4.3 x 10^3 yr, and tau/B(mu K0L) > 6.5 x 10^3 yr.

hep-ex↗