cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Three dimensional imaging of the nucleon --- TMD (theory and phenomenology)
Creators: name: Liang, Zuo-tang
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: This is intend to provide an overview of the theoretical and phenomenological parts of the TMD (Transverse Momentum Dependent parton distribution and fragmentation functions) studies. By comparing with the theoretical framework that we have for the inclusive deep inelastic lepton-nucleon scattering and the one-dimensional imaging of the nucleon, I try to outline what we need to do in order to construct a comprehensive theoretical framework for semi-inclusive reactions and the three dimensional imaging of the nucleon. After that, I try to give an overview of what we have already achieved and make an outlook for the future.
description: plenary talk at the 21st International Symposium on Spin Physics, Oct 20-24, 2014, Peking University, Beijing, China
On Presolar Stardust Grains from CO Classical Novae
Creators: name: Downen, L.N.
name: Starrfield, S.
name: Nittler, L.R.
name: José, J.
name: Iliadis, C.
Publisher: name: Institute of Physics Publishing
Year: 2018

description: About 30%-40% of classical novae produce dust 20-100 days after the outburst, but no presolar stardust grains from classical novae have been unambiguously identified yet. Although several studies claimed a nova paternity for certain grains, the measured and simulated isotopic ratios could only be reconciled, assuming that the grains condensed after the nova ejecta mixed with a much larger amount of close-to-solar matter. However, the source and mechanism of this potential post-explosion dilution of the ejecta remains a mystery. A major problem with previous studies is the small number of simulations performed and the implied poor exploration of the large nova parameter space. We report the results of a different strategy, based on a Monte Carlo technique, that involves the random sampling over the most important nova model parameters: the white dwarf composition; the mixing of the outer white dwarf layers with the accreted material before the explosion; the peak temperature and density; the explosion timescales; and the possible dilution of the ejecta after the outburst. We discuss and take into account the systematic uncertainties for both the presolar grain measurements and the simulation results. Only those simulations that are consistent with all measured isotopic ratios of a given grain are accepted for further analysis. We also present the numerical results of the model parameters. We identify 18 presolar grains with measured isotopic signatures consistent with a CO nova origin, without assuming any dilution of the ejecta. Among these, the grains G270-2, M11-334-2, G278, M11-347-4, M11-151-4, and Ag2-6 have the highest probability of a CO nova paternity.
Cosmic ray propagation in the interstellar magnetic fields
Creators: name: Giacinti, G.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The propagation of TeV-PeV cosmic rays (CR) in our Galaxy can be described as a diffusive process. We discuss here two effects, with important observational consequences, that cannot be predicted by the diffusion approximation in its usual form. First, we present an explanation for the CR anisotropies observed at small angular scales on the sky. We show that the local magnetic field configuration within a CR mean free path from Earth naturally results in CR flux anisotropies at small and medium scales. Second, we point out that TeV-PeV CRs should be expected to diffuse strongly anisotropically in the interstellar medium on scales smaller than the maximum scale of spatial fluctuations of the field, $\sim 100$ pc. This notably questions the usual assumptions on CR diffusion around sources.
description: 9 pages, 4 figures. Published in Plasma Physics and Controlled Fusion. Invited paper for the 40th EPS conference on plasma physics (2013)
SPWarn
Creators: name: Pasuksmit, Jirat
Publisher: name: figshare
Year: 2023
Subjects: Empirical software engineering

description: sp-change-replication A replication package for a journal paper entitled "Understanding and Predicting the change of Story Points". This package contains two main parts: 'data' issueLists: List of work items used in this study. reverted: Information extracted from JIRA for each projects. The information of each work items is reverted to the time when they are assigned to a sprint (+1 hour). rq2_inprogresstime: the duration that a work item's status was set to 'in progress' rq3_coding_result: Outcome of our open coding and manual classifications in RQ3-Qualitative rq4_feature: Feature extracted from work items to be used to train the classifiers in RQ4 rq4_metrics_influence: A list of metrics ranked by how much each of them influencing the model's prediction. rq4_model: Trained models in RQ4. rq4_performance: Performance of the model (for each model and mean value). The performance is calculated for each of the 100 models (built based on each bootstrap dataset). 'rscript' RQ2_relationship_sp_devtime.R: Statistics summary of our models in RQ2. RQ3_infochange.R: The contingency table of the work items with changed story points and the work items with changed information (with Fisher's exact test). RQ4.R: Builds OneR (baseline), Logistic Regression, Support Vector Machine, and Random Forest classifiers RQ4_performance_measure.R: Measures the model's performance of our classifiers. RQ4_performance_comparison.R: Evaluate the model's performance of our classifiers with baseline approach. RQ4_influence_metric_odds.R: Observe the effect of the change of reporter-stable-sp-rate to the odds (likelihood) that the SP will be changed. RQ4_influence_metric_varrank.R: Examining the influence of metrics in the models REQUIREMENTS We recommend to run the code on Anaconda. Requires R version 3.6.1 (2019-07-05) On Conda command line, run: conda install -c r rstudio Main package required: dplyr 0.8.0.1 plyr 1.8.4 car 3.0-10 multilevel 2.6 lmtest 0.9-38 nlme 3.1-139 scales 1.0.0 effsize 0.8.1 tidyr 0.8.3 fps 2.2-9 rms 6.2-0 randomForest 4.6-14 e1071 1.7-7 ROCR 1.0-11 caret 6.0-88 OneR 2.2 coin 1.4-1 rlang 0.4.11 ScottKnottESD 2.0.3 After that, install Rnalytica 0.1.1 using these following instructions: Install R package "devtools" 2.4.1 Install DMwR from the file by ... RUN R command: install.packages('[PATH_TO_THIS_PACKPAGE]/DMwR_0.4.1.tar.gz', repos = NULL, type="source") Install Rnalytica using devtools by .. RUN R command: devtools::install_github('software-analytics/Rnalytica') Full list of installed packages can be found in R-requirements.csv
Gravitational wave echoes from strange stars for various equations of state
Creators: name: Bora, Jyatsnasree
name: Goswami, Umananda Dev
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The tentative Gravitational Wave Echo (GWE) at a frequency of about $72\,Hz$ has been recently claimed at $4.2σ$ significance level in the GW170817 event. GWEs can be used as a tool to study the characteristics of ultra-compact stellar objects. Considering the final ultra-compact, post-merger object as a strange star, the GWE frequency can be calculated. However, GWEs are observed for only those compact stellar structures whose compactness lies in between 0.33 and 0.44. Alternatively, GWE can be obtained for those compact stars which feature a photon sphere and compactness not crossing the Buchdahl's limit radius $R_{B}=9/4M$. A photon sphere is a surface located at $R=3M$, $R$ being the radius and $M$ is the total mass of the ultra-compact object. Recently using the simplest MIT Bag model Equation of State (EoS) it has been reported that strange stars can produce GWEs with frequencies of tens of kilohertz. In view of this, for a comparative study, we have calculated the respective echo frequencies associated with strange stars by considering three models of strange star EoSs, viz., MIT bag model, linear and polytropic EoSs \cite{JB}. We found that, not being too stiff the polytropic EoS can not emit GWE, whereas the MIT Bag model and the linear EoSs can emit GWEs at a frequency range of about tens of kilohertz. Also, GWE frequency increases with the increase in values of bag constant $B$ and decreases with the increasing values of linear constant $b$. So a model-dependent nature of GWE frequencies is observed.
description: 3 pages, 1 figure
Empirical Study of Traffic Velocity Distribution and its Effect on VANETs Connectivity
Creators: name: Abuelenin, Sherif M.
name: Abul-Magd, Adel Y.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: In this article we use real traffic data to confirm that vehicle velocities follow Gaussian distribution in steady state traffic regimes (free-flow, and congestion). We also show that in the transition between free-flow and congestion, the velocity distribution is better modeled by generalized extreme value distribution (GEV). We study the effect of the different models on estimating the probability distribution of connectivity duration between vehicles in vehicular ad-hoc networks.
description: 5 pages, 5 figures, presented at the ICCVE 2014 (International conference on connected vehicles & expo); http://www.iccve.org/
Transport Coefficients in Yang--Mills Theory and QCD
Creators: name: Christiansen, Nicolai
name: Haas, Michael
name: Pawlowski, Jan M.
name: Strodthoff, Nils
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We calculate the shear viscosity over entropy density ratio $η/s$ in Yang--Mills theory from the Kubo formula using an exact diagrammatic representation in terms of full propagators and vertices using gluon spectral functions as external input. We provide an analytic fit formula for the temperature dependence of $η/s$ over the whole temperature range from a glueball resonance gas at low temperatures, to a high-temperature regime consistent with perturbative results. Subsequently we provide a first estimate for $η/s$ in QCD.
description: 5 pages, 4 figures
Hydrodynamic simulations of classical novae: Accretion onto CO white dwarfs as Sn Ia progenitors
Creators: name: Woodward, C.E.
name: Hernanz, M.
name: Starrfield, S.
name: Wagner, R.M.
name: Bose, M.
name: Jóse, J.
name: Hix, W.R.
name: Iliadis, C.
Publisher: name: Sissa Medialab Srl
Year: 2017

description: We report on our continuing studies of Classical Nova explosions by following the evolution of thermonuclear runaways (TNRs) on carbon-oxygen (CO) white dwarfs (WDs). We have varied both the mass of the WD and the composition of the accreted material. Rather than assuming that the material has mixed from the beginning, we now rely on the results of the multidimensional (multi-D) studies of mixing as a consequence of the TNRs in WDs that accreted only Solar matter. The multi-D studies find that mixing with the core occurs after the TNR is well underway and reach enrichment levels in agreement with observations of the ejecta abundances. We report on 3 studies in this paper. First, simulations in which we accrete only Solar matter with NOVA (our 1-D, fully implicit, hydro code). Second, we use MESA for similar studies in which we accrete only Solar material and compare the results. Third, we accrete Solar matter until the TNR is initiated and then switch the composition in the accreted layers to a mixed composition: either 25% core and 75% Solar or 50% core and 50% Solar. The amount of accreted material is inversely proportional to the initial 12 C abundance. Thus, accreting Solar material results in more material to fuel the outburst - much larger than in the earlier studies where mixed materials were used from the beginning. We tabulate the amount of ejected gases, their velocities, and abundances. We predict the amount of 7 Li and 7 Be produced and ejected by the explosion and compare our predictions to our Large Binocular Telescope (LBT) high dispersion spectra which determined the abundance of 7 Li in nova V5668 Sgr. Finally, many of these simulations eject significantly less mass than accreted and, therefore, the WD is growing in mass toward the Chandrasekhar Limit.
K-invariants in the algebra U(g) $\otimes$ C(p) for the group SU(2,1)
Creators: name: Prlić, Ana
Publisher: name: arXiv
Year: 2014
Subjects: subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: Let $\mathfrak{g} = \mathfrak{k} \oplus \mathfrak{p}$ be the Cartan decomposition of the complexified Lie algebra $\mathfrak{g}=\mathfrak{sl}(3,\mathbb{C})$ of the group $G=SU(2,1)$. Let $K=S(U(2) \times U(1))$; so $K$ is a maximal compact subgroup of $G$. Let $U(\mathfrak{g})$ be the universal enveloping algebra of $\mathfrak{g}$, and let $C(\mathfrak{p})$ be the Clifford algebra with respect to the trace form $B(X,Y)=\text{tr}(XY)$ on $\mathfrak{p}$. We are going to prove that the algebra of K-invariants in $U(\mathfrak{g}) \otimes C(\mathfrak{p})$ is generated by five explicitly given elements. This is useful for studying algebraic Dirac induction for $(\mathfrak{g},K)$-modules. Along the way we will also recover the (well known) structure of the algebra $U(\mathfrak{g})^K$.
description: 18 pages
Prequantum Classical Statistical Field Theory: Simulation of Probabilities of Photon Detection with the Aid of Classical Brownian Motion
Creators: name: Khrennikov, Andrei
Publisher: name: arXiv
Year: 2014
Subjects: subject: Quantum Physics (quant-ph)
subject: Probability (math.PR)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: In this paper we present results of numerical simulation based on Prequantum Classical Statistical Field Theory (PCSFT), a model with hidden variables of the field-type reproducing probabilistic predictions of quantum mechanics (QM). PCSFT is combined with measurement theory based on detectors of the threshold type. The latter describes discrete events corresponding to the continuous fields model, PCSFT. Numerical modeling demonstrated that the classical Brownian motion (the Wiener process valued in complex Hilbert space) producing clicks when approaching the detection threshold gives probabilities of detection predcited by the formalism QM (as well as PCSFT). This numerical result is important, since the transition from PCSFT to the threshold detection has a complex mathematical structure (in the framework of classical random processes) and it was modeled only approximately. We also perform numerical simulation for the PCSFT-value of the coefficient of second order coherence. Our result matches well with the prediction of quantum theory. Thus, opposite to semiclassical theory, PCSFT cannot be rejected as a consequence of measurements of $g^{(2)}(0).$ Finally, we analyze the output of the recent experiment performed in NIST questioning the validity of some predictions of PCSFT.
A low-background γγ-coincidence spectrometer for radioisotope studies
Creators: name: Tonin, Y.
name: Darken, M.
name: Dearing, C.
name: Emamian, M.
name: Iliadis, C.
name: Tillett, A.
name: Dermigny, J.
name: Bucay, I.
name: Smith, R.L.
name: Orbon, M.
Publisher: name: Elsevier B.V.
Year: 2017

description: The performance of a new, low-background NaI(Tl) spectrometer, based on γγ-coincidence counting, is discussed. We present experimental coincidence efficiencies, timing resolutions, background count rates, and minimum detectable activities. The spectrometer has been simulated using Geant4, and the results are used for estimating coincidence efficiencies for volume sources. To test the device, we measured the cosmogenic 26Al activity in a small (17.7 g) meteorite fragment. We find a value of 52.9±7.8dpm∕kg, in agreement with the activity measured previously in a much larger fragment of the same meteorite using a HPGe detector.
New symmetries for the Gravitational S-matrix
Creators: name: Campiglia, Miguel
name: Laddha, Alok
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In [15] we proposed a generalization of the BMS group G which is a semidirect product of supertranslations and smooth diffeomorphisms of the conformal sphere. Although an extension of BMS, G is a symmetry group of asymptotically flat space times. By taking G as a candidate symmetry group of the quantum gravity S-matrix, we argued that the Ward identities associated to the generators of Diff(S^2) were equivalent to the Cachazo-Strominger subleading soft graviton theorem. Our argument however was based on a proposed definition of the Diff(S^2) charges which we could not derive from first principles as G does not have a well defined action on the radiative phase space of gravity. Here we fill this gap and provide a first principles derivation of the Diff(S^2) charges. The result of this paper, in conjunction with the results of [4, 15] prove that the leading and subleading soft theorems are equivalent to the Ward identities associated to G.
description: 19 pages
Current hot questions on the s process in AGB stars
Creators: name: Tagliente, G.
name: Karakas, A.I.
name: Rauscher, T.
name: D'Orazi, V.
name: Garcia-Hernandez, D.A.
name: Lugaro, M.
name: Iliadis, C.
name: Campbell, S.W.
name: Stancliffe, R.J.
Publisher: name: Institute of Physics Publishing
Year: 2016

description: Asymptotic giant branch (AGB) stars are a main site of production of nuclei heavier than iron via the s process. In massive (>4 M⊙) AGB stars the operation of the 22Ne neutron source appears to be confirmed by observations of high Rb enhancements, while the lack of Tc in these stars rules out 13C as a main source of neutrons. The problem is that the Rb enhancements are not accompanied by Zr enhancements, as expected by s-process models. This discrepancy may be solved via a better understanding of the complex atmospheres of AGB stars. Second- generation stars in globular clusters (GCs), on the other hand, do not show enhancements in any s-process elements, not even Rb. If massive AGB stars are responsible for the composition of these GC stars, they may have evolved differently in GCs than in the field. In AGB stars of lower masses, 13C is the main source of neutrons and we can potentially constrain the effects of rotation and proton-ingestion episodes using the observed composition of post-AGB stars and of stardust SiC grains. Furthermore, independent asteroseismology observations of the rotational velocities of the cores of red giants and of white dwarves will play a fundamental role in helping us to better constrain the effect of rotation. Observations of carbon-enhanced metal-poor stars enriched in both Ba and Eu may require a neutron flux in-between the s and the r process, while the puzzling increase of Ba as function of the age in open clusters, not accompanied by increase in any other element heavier than iron, require further observational efforts. Finally, stardust SiC provides us high-precision constraints to test nuclear inputs such as neutron-capture cross sections of stable and unstable isotopes and the impact of excited nuclear states in stellar environments.
Multiplet classification for SU(n,n)
Creators: name: Dobrev, V. K.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: In the present paper we review our project of systematic construction of invariant differential operators on the example of the non-compact algebras su(n,n) for n=2,3,4. We give explicitly the main multiplets of indecomposable elementary representations and some reduced multiplets. We give explicitly the minimal representations. Due to the recently established parabolic relations the multiplet classification results are valid also for the algebras sl(2n,R) and when n=2k for the algebras su*(4k) with suitably chosen maximal parabolic subalgebras.
description: 21 pages, 16 figures, Review paper based on Plenary talk at the International Conference on Integrable Systems and Quantum Symmetries, Prague, June 2014
InAs/MoRe hybrid semiconductor/superconductor nanowire devices
Creators: name: Kousar, Bilal
name: Carrad, Damon J.
name: Stampfer, Lukas
name: Krogstrup, Peter
name: Nygård, Jesper
name: Jespersen, Thomas S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Implementing superconductors capable of proximity-inducing a large energy-gap in semiconductors in the presence of strong magnetic fields is a major goal towards applications of semiconductor/superconductor hybrid materials in future quantum information technologies. Here, we study the performance of devices consisting of InAs nanowires in electrical contact to molybdenum-rhenium (MoRe) superconducting alloys. The MoRe thin films exhibit transition temperatures ~10 K and critical fields exceeding 6 T. Normal/superconductor devices enabled tunnel spectroscopy of the corresponding induced superconductivity, which was maintained up to ~10 K, and MoRe based Josephson devices exhibit supercurrents and multiple Andreev reflections. We determine an induced superconducting gap lower than expected from the transition temperature, and observe gap softening at finite magnetic field. These may be common features for hybrids based on large gap, type-II superconductors. The results encourage further development of MoRe-based hybrids.
Structural, electronic and topological properties of 3D TmBi compound
Creators: name: Ragragui, M.
name: Drissi, L. B.
name: Lounis, S.
name: Saidi, E. H.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Using density functional theory based methods we report the structural, electronic and topological properties of the FCC crystal compound TmBi. This material is found to be dynamically stable and shows a non magnetic semimetalic character. By tuning the spin-orbit coupling, we observe a significant change in the band structure, and the occurrence of band inversion along $Γ-X$ direction. The parity product at time-reversal invariant momentum points and the Wannier charge center calculations provide a topological index $Z_{2}=1$ on the $k_{j}=0$ plane (with $j=1,2$ and $3$) revealing the non trivial topological character of TmBi. The existence of topologically protected surface states of TmBi through the observation of a Dirac cones at $\bar{X}$ point confirm our finding. The present work could inspire platforms for exploring novel topological states within the family of rare-earth monobismuthides.
description: 14 pages, 8 figures
On the Distribution of the Greatest Common Divisor of Gaussian Integers
Creators: name: Bradley, Tai-Danae
name: Cheng, Yin Choi
name: Luo, Yan Fei
Publisher: name: arXiv
Year: 2015
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11N37, 11A05, 11K65, 60E05

description: For a pair of random Gaussian integers chosen uniformly and independently from the set of Gaussian integers of norm $x$ or less as $x$ goes to infinity, we find asymptotics for the average norm of their greatest common divisor, with explicit error terms. We also present results for higher moments along with computational data which support the results for the second, third, fourth, and fifth moments. The analogous question for integers is studied by Diaconis and Erdös.
description: 13 pages, 4 figures
Measuring charge distribution of molecular cations by atomic Coulomb probe microscope
Creators: name: Yu, Xitao
name: Hu, Xiaoqing
name: Zhou, Jiaqi
name: Zhang, Xinyu
name: Zhao, Xinning
name: Jia, Shaokui
name: Xue, Xiaorui
name: Ren, Dianxiang
name: Li, Xiaokai
name: Wu, Yong
name: Ren, Xueguang
name: Luo, Sizuo
name: Ding, Dajun
Publisher: name: arXiv
Year: 2022
Subjects: subject: Atomic and Molecular Clusters (physics.atm-clus)
subject: FOS: Physical sciences

description: Imaging the charge distributions and structures of molecules and clusters will promote the understanding of the dynamics of the quantum system. Here, we report a method by using an Ar atom as a tip to probe the charge distributions of benzene (Bz) cations in gas phase. Remarkably, the measured charge distributions of Bz cation (QH =0.204,QC=-0.037)and dication (QH =0.248,QC=0.0853)agree well with the calculated Mulliken distributions,and the structures of Bz dimer is reconstructed by using the measured charge distributions. The structures of two Bz dimer isomers (T-shaped and PD isomers) can be resolved from the measured inter-molecular potential V(R) between two Bz ions, and the structures of Bz dimer agree well with the theoretical predictions.
description: 7 pages, 3 Figures
Performance of the gas gain monitoring system of the CMS RPC muon detector
Creators: name: Benussi, L.
name: Bianco, S.
name: Passamonti, L.
name: Piccolo, D.
name: Pierluigi, D.
name: Raffone, G.
name: Russo, A.
name: Saviano, G.
name: Ban, Y.
name: Cai, J.
name: Li, Q.
name: Liu, S.
name: Qian, S.
name: Wang, D.
name: Xu, Z.
name: Zhang, F.
name: Choi, Y.
name: Kim, D.
name: Choi, S.
name: Hong, B.
name: Kang, J. W.
name: Kang, M.
name: Kwon, J. H.
name: Lee, K. S.
name: Park, S. K.
name: Pant, L.
name: Singh, V. B. J.
name: Kumar, A. M. R.
name: Kumar, S.
name: Chand, S.
name: Singh, A.
name: Bhandari, V. K.
name: Mohanty, A. K.
name: Thomas, R. G.
name: Sehgal, R.
name: Chudasama, R.
name: Sehgal, S. T.
name: Cimmino, A.
name: Ocampo, A.
name: Thyssen, F.
name: Tytgat, M.
name: Van Doninck, W.
name: Ahmad, A.
name: Muhammad, S.
name: Shoaib, M.
name: Hoorani, H.
name: Awan, I.
name: Ali, I.
name: Ahmed, W.
name: Asqhar, M. I.
name: Shahzad, H.
name: Sayed, A.
name: Ibrahim, A.
name: Assran, Y.
name: Aly, R.
name: Radi, A.
name: Elkafrawi, T.
name: Sharma, A.
name: Colafranceschi, S.
name: Abbrescia, M.
name: Verwilligen, P.
name: Meola, S.
name: Cavallo, N.
name: Braghieri, A.
name: Montagna, P.
name: Riccardi, C.
name: Salvini, P.
name: Vitulo, P.
name: Dimitrov, A.
name: Hadjiiska, R.
name: Litov, L.
name: Pavlov, B.
name: Petkov, P.
name: Aleksandrov, A.
name: Genchev, V.
name: Iaydjiev, P.
name: Rodozov, M.
name: Sultanov, G.
name: Vutova, M.
name: Stoykova, S.
name: Ibargüen, H. S.
name: Morales, M. I. Pedraza
name: Bernardino, S. Carpinteyro
name: Bagaturia, I.
name: Tsamalaidze, Z.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: The RPC muon detector of the CMS experiment at the LHC (CERN, Geneva, Switzerland) is equipped with a Gas Gain Monitoring (GGM) system. A report on the stability of the system during the 2011-2012 data taking run is given, as well as the observation of an effect which suggests a novel method for the monitoring of gas mixture composition.
description: Presented at RPC2014, Beijing, China. Accepted for publication on JINST
Sparse Gaussian Process Hyperparameters: Optimize or Integrate?
Creators: name: Lalchand, Vidhi
name: Bruinsma, Wessel P.
name: Burt, David R.
name: Rasmussen, Carl E.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: Methodology (stat.ME)
subject: FOS: Computer and information sciences
subject: G.3
subject: 60G15 (Primary)

description: The kernel function and its hyperparameters are the central model selection choice in a Gaussian proces (Rasmussen and Williams, 2006). Typically, the hyperparameters of the kernel are chosen by maximising the marginal likelihood, an approach known as Type-II maximum likelihood (ML-II). However, ML-II does not account for hyperparameter uncertainty, and it is well-known that this can lead to severely biased estimates and an underestimation of predictive uncertainty. While there are several works which employ a fully Bayesian characterisation of GPs, relatively few propose such approaches for the sparse GPs paradigm. In this work we propose an algorithm for sparse Gaussian process regression which leverages MCMC to sample from the hyperparameter posterior within the variational inducing point framework of Titsias (2009). This work is closely related to Hensman et al. (2015b) but side-steps the need to sample the inducing points, thereby significantly improving sampling efficiency in the Gaussian likelihood case. We compare this scheme against natural baselines in literature along with stochastic variational GPs (SVGPs) along with an extensive computational analysis.
description: NeurIPS 2022
Elastic properties of moiré lattices in epitaxial two-dimensional materials
Creators: name: Artaud, Alexandre
name: Rougemaille, Nicolas
name: Vlaic, Sergio
name: Renard, Vincent T.
name: Atodiresei, Nicolae
name: Coraux, Johann
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Unlike conventional two-dimensional (2D) semiconductor superlattices, moiré patterns in 2D materials are flexible and their electronic, magnetic, optical, and mechanical properties depend on their topography. Within a continuous+atomistic theory treating 2D materials as crystalline elastic membranes, we abandon the flat-membrane scenario usually assumed for these materials and address out-of-plane deformations. We confront our predictions to experimental analyses on model systems, epitaxial graphene, and MoS$_2$ on metals and reveal that compression/expansion and bending energies stored in the membrane can compete with adhesion energy, leading to a subtle moiré wavelength selection and the formation of wrinkles.
description: 7 pages, 3 figures
γ-Ray spectroscopy using a binned likelihood approach
Creators: name: Dermigny, J.R.
name: Kelly, K.J.
name: Buckner, M.Q.
name: Iliadis, C.
Publisher: name: Elsevier B.V.
Year: 2016

description: The measurement of a reaction cross section from a pulse height spectrum is a ubiquitous problem in experimental nuclear physics. In γ-ray spectroscopy, this is accomplished frequently by measuring the intensity of full-energy primary transition peaks and correcting the intensities for experimental artifacts, such as detection efficiencies and angular correlations. Implicit in this procedure is the assumption that full-energy peaks do not overlap with any secondary peaks, escape peaks, or environmental backgrounds. However, for complex γ-ray cascades, this is often not the case. Furthermore, this technique is difficult to adapt for coincidence spectroscopy, where intensities depend not only on the detection efficiency, but also the detailed decay scheme. We present a method that incorporates the intensities of the entire spectrum (e.g., primary and secondary transition peaks, escape peaks, Compton continua, etc.) into a statistical model, where the transition intensities and branching ratios can be determined using Bayesian statistical inference. This new method provides an elegant solution to the difficulties associated with analyzing coincidence spectra. We describe it in detail and examine its efficacy in the analysis of 18O(p,γ)19F and 25Mg(p,γ)26Al resonance data. For the 18O(p,γ)19F reaction, the measured branching ratios improve upon the literature values, with a factor of 3 reduction in the uncertainties.
Experimental Estimation of Average Fidelity of a Clifford Gate on a 7-qubit Quantum Processor
Creators: name: Lu, Dawei
name: Li, Hang
name: Trottier, Denis-Alexandre
name: Li, Jun
name: Brodutch, Aharon
name: Krismanich, Anthony P.
name: Ghavami, Ahmad
name: Dmitrienko, Gary I.
name: Long, Guilu
name: Baugh, Jonathan
name: Laflamme, Raymond
Publisher: name: arXiv
Year: 2014
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum gates in experiment are inherently prone to errors that need to be characterized before they can be corrected. Full characterization via quantum process tomography is impractical and often unnecessary. For most practical purposes, it is enough to estimate more general quantities such as the average fidelity. Here we use a unitary 2-design and twirling protocol for efficiently estimating the average fidelity of Clifford gates, to certify a 7-qubit entangling gate in a nuclear magnetic resonance quantum processor. Compared with more than $10^8$ experiments required by full process tomography, we conducted 1656 experiments to satisfy a statistical confidence level of 99%. The average fidelity of this Clifford gate in experiment is 55.1%, and rises to 87.5% if the infidelity due to decoherence is removed. The entire protocol of certifying Clifford gates is efficient and scalable, and can easily be extended to any general quantum information processor with minor modifications.
description: 5 pages, 2 figures
Using MPI For Distributed Hyper-Parameter Optimization and Uncertainty Evaluation
Creators: name: Pautsch, Erik
name: Li, John
name: Rizzi, Silvio
name: Thiruvathukal, George K.
name: Pantoja, Maria
Publisher: name: figshare
Year: 2023
Subjects: classificationCode: 401002
subject: Engineering education
classificationCode: 460804
subject: Computing education
classificationCode: 460607
subject: High performance computing

description: Deep Learning (DL) methods have recently dominated the fields of Machine Learning (ML). Most DL models assume that the input data distribution is identical between testing and validation, though they often are not. For example, if we train a traffic sign classifier, the model might confidently but incorrectly classify a graffitied stop sign as a speed limit sign. Often ML provides high-confidence (softmax) output for out-of-distribution input that should have been classified as "I don't know". By adding the capability of propagating uncertainty to our results, the model can provide not just a single prediction, but a distribution over predictions that will allow the user to determine the model's reliability and whether it needs to be deferred to a human expert. Uncertainty estimation is computationally expensive; in this assignment, we will learn to accelerate the calculations using common distributed systems divide and conquer techniques. This assignment is part of a Distributed Computing (DC) class (undergraduate), where most students have no experience in ML. We explain the ML concepts necessary to understand the problem and then explain where in the code the independent tasks are generated and how they can be distributed among rank nodes using MPI4Py as the programming language. Set of files given to students:
Characterization of a 10B-doped liquid scintillator as a capture-gated neutron spectrometer
Creators: name: Longland, R.
name: Hunt, S.
name: Iliadis, C.
Publisher: name: Elsevier
Year: 2016

description: We use a 250 MHz digitizer to characterize the pulse shape discrimination of a BC-523A 10B-doped liquid scintillator with capture-gating capabilities. Our results are compared to recent work claiming pulse shape discrimination between fast and thermal neutron signals. The capture event is identified, and we explain the origin of signals that are often misinterpreted. We use the time-of-flight method to measure the detector energy resolution for fast incident monoenergetic neutrons and the intrinsic neutron detection efficiency. Monte Carlo simulations are performed and we find agreement between measured and simulated results. These steps are important for understanding 10B-doped capture-gated spectroscopy in mixed radiation environments, as efficiencies using capture-gating are rarely reported in the literature.
Physical Measures for Infinitely Renormalizable Lorenz Maps
Creators: name: Martens, Marco
name: Winckler, Björn
Publisher: name: arXiv
Year: 2014
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: 37E20

description: A physical measure on the attractor of a system describes the statistical behavior of typical orbits. An example occurs in unimodal dynamics. Namely, all infinitely renormalizable unimodal maps have a physical measure. For Lorenz dynamics, even in the simple case of infinitely renormalizable systems, the existence of physical measures is more delicate. In this article we construct examples of infinitely renormalizable Lorenz maps which do not have a physical measure. A priori bounds on the geometry play a crucial role in (unimodal) dynamics. There are infinitely renormalizable Lorenz maps which do not have a priori bounds. This phenomenon is related to the position of the critical point of the consecutive renormalizations. The crucial technical ingredient used to obtain these examples without a physical measure, is the control of the position of these critical points.
description: 26 pages, 1 figure
Using MPI For Distributed Hyper-Parameter Optimization and Uncertainty Evaluation
Creators: name: Pautsch, Erik
name: LI, John
name: Rizzi, Silvio
name: Thiruvathukal, George K.
name: Pantoja, Maria
Publisher: name: figshare
Year: 2023
Subjects: classificationCode: 401002
subject: Engineering education
classificationCode: 460804
subject: Computing education
classificationCode: 460607
subject: High performance computing

description: Deep Learning (DL) methods have recently dominated the fields of Machine Learning (ML). Most DL models assume that the input data distribution is identical between testing and validation, though they often are not. For example, if we train a traffic sign classifier, the model might confidently but incorrectly classify a graffitied stop sign as a speed limit sign. Often ML provides high-confidence (softmax) output for out-of-distribution input that should have been classified as "I don't know". By adding the capability of propagating uncertainty to our results, the model can provide not just a single prediction, but a distribution over predictions that will allow the user to determine the model's reliability and whether it needs to be deferred to a human expert. Uncertainty estimation is computationally expensive; in this assignment, we will learn to accelerate the calculations using common distributed systems divide and conquer techniques. This assignment is part of a Distributed Computing (DC) class (undergraduate), where most students have no experience in ML. We explain the ML concepts necessary to understand the problem and then explain where in the code the independent tasks are generated and how they can be distributed among rank nodes using MPI4Py as the programming language. Set of files given to students:
Rate and uncertainty of the 18Ne(α,p)21Na reaction from Monte-Carlo simulations
Creators: name: Longland, R.
name: Mohr, P.
name: Iliadis, C.
Publisher: name: Proceedings of Science (PoS)
Year: 2014

description: The reaction rate NA«σν» of the 18Ne(α,p)21Na reaction has been calculated from resonance energies and resonance strengths using the Monte-Carlo technique. This results in a recommended reaction rate with a well-constrained uncertainty which is below a factor of 2 in the most relevant temperature range of 0.5 ≤ T9 ≤ 2. The overall uncertainty includes contributions from the resonance energies, resonance strengths, and for the first time from uncertain Jπ assignments. The new rate is based on experimental resonance energies and calculated resonance strengths which have been completely re-analyzed, leading to slightly lower strengths than in previous studies. The new recommended reaction rate is close to previous results which had to be taken as a compromise from discrepant results of different indirect approaches.
Physics in Very Strong Magnetic Fields: Introduction and Overview
Creators: name: Lai, Dong
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: This paper provides an introduction to a number of astrophysics problems related to strong magnetic fields. The first part deals with issues related to atoms, condensed matter and high-energy processes in very strong magnetic fields, and how these issues influence various aspects of neutron star astrophysics. The second part deals with classical astrophysical effects of magnetic fields: Even relatively "weak" fields can play a strong role in various astrophysical problems, ranging from stars, accretion disks and outflows, to the formation and merger of compact objects.
description: 16 pages. To be published in The Strongest Magnetic Fields in the Universe (Space Sciences Series of ISSI, Springer), Space Science Reviews
Reconstruction of Zigzag Graphene Edges: Energetics, Kinetics and Residual Defects
Creators: name: Polynskaya, Yulia G.
name: Lebedeva, Irina V.
name: Knizhnik, Andrey A.
name: Popov, Andrey M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Ab initio calculations are performed to study consecutive reconstruction of a zigzag graphene edge. According to the obtained energy profile along the reaction pathway, the first reconstruction step, formation of the first pentagon-heptagon pair, is the slowest one, while the growth of an already nucleated reconstructed edge domain should occur steadily at a much higher rate. Domains merge into one only in 1/4 of cases when they get in contact, while in the rest of the cases, residual defects are left. Structure, energy and magnetic properties of these defects are studied. It is found that spontaneous formation of pairs of residual defects (i.e. spontaneous domain nucleation) in the fully reconstructed edge is unlikely at temperatures below 1000 K. Using a kinetic model, we show that the average domain length is of several $\mathrmμ$m at room temperature and it decreases exponentially upon increasing the temperature at which the reconstruction takes place.
description: 5 pages, 4 figures
Cross-section measurements of the Kr86(γ,n) reaction to probe the s-process branching at Kr85
Creators: name: Lugaro, M.
name: Tornow, W.
name: Schwengner, R.
name: Raut, R.
name: Goriely, S.
name: Rusev, G.
name: Banu, A.
name: Kelley, J.H.
name: Tonchev, A.P.
name: Iliadis, C.
name: Tsoneva, N.
name: Buntain, J.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2013

description: We have carried out photodisintegration cross-section measurements on Kr86 using monoenergetic photon beams ranging from the neutron separation energy, Sn=9.86 MeV, to 13 MeV. We combine our experimental Kr86(γ,n)Kr85 cross section with results from our recent Kr86(γ,γ′) measurement below the neutron separation energy to obtain the complete nuclear dipole response of Kr86. The new experimental information is used to predict the neutron capture cross section of Kr85, an important branching point nucleus on the abundance flow path during s-process nucleosynthesis. Our new and more precise Kr85(n,γ)Kr86 cross section allows us to produce more precise predictions of the Kr86 abundance from s-process models. In particular, we find that the models of the s process in asymptotic giant branch stars of mass <1.5MâŠ™, where the C13 neutron source burns convectively rather than radiatively, represent a possible solution for the highest Kr86â̂Kr82 ratios observed in meteoritic stardust SiC grains.
Uniform Approach to Double Shuffle and Duality Relations of Various q-Analogs of Multiple Zeta Values via Rota-Baxter Algebras
Creators: name: Zhao, Jianqiang
Publisher: name: arXiv
Year: 2014
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11M32, 16W50, 68R15

description: The multiple zeta values (MZVs) have been studied extensively in recent years. Currently there exist a few different types of $q$-analogs of the MZVs ($q$-MZVs) defined and studied by mathematicians and physicists. In this paper, we give a uniform treatment of these $q$-MZVs by considering their double shuffle relations (DBSFs) and duality relations. The main idea is a modification and generalization of the one used by Castillo Medina et al. who have considered the DBSFs of a special type of $q$-MZVs. We generalize their method to a few other types of $q$-MZVs including the one defined by the author in 2003. With different approach, Takeyama has already studied this type by "regularization" and observed that there exist $\mathbb Q$-linear relations which are not consequences of the DBSFs. He also discovered a new family of relations which we call the duality relations in this paper. This deficiency of DBSFs occurs among other types, too, so we generalize the duality relations to all of these values and find that there are still some missing relations. This leads to the most general type of $q$-MZVs together with a new kind of relations called $\bf P$-$\bf Q$ relations which are used to lower the deficiencies further. As an application, we will confirm a conjecture of Okounkov on the dimensions of certain $q$-MZV spaces, either theoretically or numerically, for the weight up to 12. Some relevant numerical data are provided at the end.
description: 32 pages, 9 tables
Optimal control for state preparation in two-qubit open quantum systems driven by coherent and incoherent controls via GRAPE approach
Creators: name: Petruhanov, Vadim
name: Pechen, Alexander
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences
subject: 81Q93

description: In this work, we consider a model of two qubits driven by coherent and incoherent time-dependent controls. The dynamics of the system is governed by a Gorini-Kossakowski-Sudarshan-Lindblad master equation, where coherent control enters into the Hamiltonian and incoherent control enters into both the Hamiltonian (via Lamb shift) and the dissipative superoperator. We consider two physically different classes of interaction with coherent control and study the optimal control problem of state preparation formulated as minimization of the Hilbert-Schmidt distance's square between the final density matrix and a given target density matrix at some fixed target time. Taking into account that incoherent control by its physical meaning is a non-negative function of time, we derive an analytical expression for the gradient of the objective and develop optimization approaches based on adaptation for this problem of GRadient Ascent Pulse Engineering (GRAPE). We study evolution of the von Neumann entropy, purity, and one-qubit reduced density matrices under optimized controls and observe a significantly different behavior of GRAPE optimization for the two classes of interaction with coherent control in the Hamiltonian.
Sea ice floes dissipate the energy of steep ocean waves
Creators: name: Toffoli, Alessandro
name: Bennetts, Luke G.
name: Meylan, Michael H.
name: Cavaliere, Claudio
name: Alberello, Alberto
name: Elsnab, John
name: Monty, Jason P.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: FOS: Physical sciences

description: Wave attenuation by ice floes is an important parameter for modelling the Arctic Oceans. At present, attenuation coefficients are extracted from linear models as a function of the incident wave period and floe thickness. Recent explorations in the Antarctic Mixed Ice Zone (MIZ) revealed a further dependence on wave amplitude, suggesting that nonlinear contributions are non-negligible. An experimental model for wave attenuation by a single ice floe in a wave flume is here presented. Observations are compared with linear predictions based on wave scattering. Results indicate that linear models perform well under the effect of gently sloping waves. For more energetic wave fields, however, transmitted wave height is normally over predicted. Deviations from linearity appear to be related to an enhancement of wave dissipation induced by unaccounted wave-ice interaction processes, including the floe over wash.