Institut f¨ur Astrophysik und GeophysikGeorg-August-Universit¨at G¨ottingen
We present a calculation of the thrust distribution in Higgs decays to quarks and gluons, HbbˉH\to b\bar{b}, HccˉH\to c\bar{c}, and HggH\to gg, including the resummation of large logarithmic corrections that arise in the two-particle limit at next-to-next-to-leading logarithmic (NNLL) accuracy, and match it to fixed-order results for three-particle decays at next-to-next-to-leading order (NNLO) in the strong coupling. The resummation is performed analytically within the ARES framework and combined with the fixed-order results using the logR matching technique. The fixed-order calculation is carried out numerically with the NNLOJET parton-level event generator, using the antenna subtraction method. We perform detailed cross-validation in the two-particle region, demonstrating that the expansion of the NNLL resummed result correctly reproduces the logarithmic structure of the fixed-order calculation to O(αs3)\mathcal{O}(\alpha_\mathrm{s}^3), up to a predictable N3^{3}LL term at O(αs3L)\mathcal{O}(\alpha_\mathrm{s}^3L). In addition to providing the first NNLO+NNLL accurate predictions for the thrust distribution in Higgs decays to quarks and gluons, we analytically extract the O(αs2)\mathcal{O}(\alpha_\mathrm{s}^2) hard-virtual correction c2c_2 and the αs3L\alpha_\mathrm{s}^3L term G31G_{31} in both the HqqˉH\to q\bar{q} (q=b,cq=b,c) and HggH\to gg decay channels.
We report on the first Belle search for a light CP-odd Higgs boson, A0A^{0}, that decays into low mass dark matter, χ\chi, in final states with a single photon and missing energy. We search for events produced via the dipion transition Υ(2S)Υ(1S)π+π\Upsilon(\textrm{2S})\rightarrow\Upsilon(\textrm{1S})\pi^{+}\pi^{-}, followed by the on-shell process Υ(1S)γA0\Upsilon(\textrm{1S})\rightarrow\gamma A^{0} with A0χχA^{0} \rightarrow\chi\chi, or by the off-shell process Υ(1S)γχχ\Upsilon(\textrm{1S})\rightarrow\gamma\chi\chi. Utilizing a data sample of 157.3 ×\times 106^{6} Υ(2S)\Upsilon(\textrm{2S}) decays, we find no evidence for a signal. We set limits on the branching fractions of such processes in the mass ranges M_{A^{0}} < 8.97 GeV/c2\textrm{GeV/}\textit{c}^{2} and M_{\chi} < 4.44 GeV/c2\textrm{GeV/}\textit{c}^{2}. We then use the limits on the off-shell process to set competitive limits on WIMP-nucleon scattering in the WIMP mass range below 5 GeV/c2\textrm{GeV/}\textit{c}^{2}.
An originally chaotic system can be controlled into various periodic dynamics. When it is implemented into a legged robot's locomotion control as a central pattern generator (CPG), sophisticated gait patterns arise so that the robot can perform various walking behaviors. However, such a single chaotic CPG controller has difficulties dealing with leg malfunction. Specifically, in the scenarios presented here, its movement permanently deviates from the desired trajectory. To address this problem, we extend the single chaotic CPG to multiple CPGs with learning. The learning mechanism is based on a simulated annealing algorithm. In a normal situation, the CPGs synchronize and their dynamics are identical. With leg malfunction or disability, the CPGs lose synchronization leading to independent dynamics. In this case, the learning mechanism is applied to automatically adjust the remaining legs' oscillation frequencies so that the robot adapts its locomotion to deal with the malfunction. As a consequence, the trajectory produced by the multiple chaotic CPGs resembles the original trajectory far better than the one produced by only a single CPG. The performance of the system is evaluated first in a physical simulation of a quadruped as well as a hexapod robot and finally in a real six-legged walking machine called AMOSII. The experimental results presented here reveal that using multiple CPGs with learning is an effective approach for adaptive locomotion generation where, for instance, different body parts have to perform independent movements for malfunction compensation.
We investigate the foreground interstellar medium along the line of sight and intracluster medium of ω\omega Centauri (ω\omega Cen) by measuring the equivalent width of Na I D absorptions from MUSE observations. The large line-of-sight velocity difference between ω\omega Cen and the foreground enables us to separate Na I D absorption contributed from atomic gas in the interstellar and intracluster medium. We find that small-scale substructures in the foreground Na I D distribution correlate with differential reddening derived from photometric methods. Using an empirical Na I D equivalent width-reddening relation, we determine an average reddening of E(BV)=0.153±0.003E(B-V)=0.153\pm0.003 mag within the half-light radius of ω\omega Cen. However, the Na I D-inferred differential reddening is significantly larger than photometric estimates. This is likely due to scatter in the Na I D-reddening relation. We find no evidence for intracluster atomic gas from spectra of horizontal branch stars, as there is no significant Na I D absorption at ω\omega Cen's systemic velocity. Given this non-detection, we place the strongest upper limit to date on the intracluster atomic gas column density in ω\omega Cen of 2.17×1018 cm2\lesssim2.17 \times 10^{18}~\rm{cm^{-2}}. We also estimate the ionized gas density from pulsar dispersion measure variations, which exceed the atomic gas limit by \sim50 times. Nevertheless, the strong correlation between dispersion measure and foreground Na I D suggests that much or all of this ionized gas resides in the foreground. Given ongoing mass loss from bright giant stars, our findings imply that the intracluster gas accumulation timescale is short, and gas removal in the cluster is likely not tied to stripping as ω\omega Cen passes through the Galactic disk.
Although all-sky surveys have led to the discovery of dozens of young planets, little is known about their atmospheres. Here, we present multi-wavelength transit data for the super Neptune-sized exoplanet, K2-33b -- the youngest (~10 Myr) transiting exoplanet to-date. We combined photometric observations of K2-33 covering a total of 33 transits spanning >2 years, taken from K2, MEarth, Hubble, and Spitzer. The transit photometry spanned from the optical to the near-infrared (0.6-4.5μ\mum), enabling us to construct a transmission spectrum of the planet. We find that the optical transit depths are nearly a factor of two deeper than those from the near-infrared. This difference holds across multiple datasets taken over years, ruling out issues of data analysis and unconstrained systematics. Surface inhomogeneities on the young star can reproduce some of the difference, but required spot coverage fractions (>60%) are ruled out by the observed stellar spectrum(<20%). We find a better fit to the transmission spectrum using photochemical hazes, which were predicted to be strong in young, moderate-temperature, and large-radius planets like K2-33b. A tholin haze with CO as the dominant gaseous carbon carrier in the atmosphere can reasonably reproduce the data with small or no stellar surface inhomogeneities, consistent with the stellar spectrum. The HST data quality is insufficient for the detection of any molecular features. More observations would be required to fully characterize the hazes and spot properties and confirm the presence of CO suggested by current data.
The Cox ring of a del Pezzo surface of degree 3 has a distinguished set of 27 minimal generators. We investigate conditions under which the initial forms of these generators generate the initial algebra of this Cox ring. Sturmfels and Xu provide a classification in the case of degree 4 del Pezzo surfaces by subdividing the tropical Grassmannian TGr(2,Q5)\operatorname{TGr}(2,\mathbb{Q}^5). After providing the necessary background on Cox-Nagata rings and Khovanskii bases, we review the classification obtained by Sturmfels and Xu. Then we describe our classification problem in the degree 3 case and its connections to tropical geometry. In particular, we show that two natural candidates, TGr(3,Q6)\operatorname{TGr}(3,\mathbb{Q}^6) and the Naruki fan, are insufficient to carry out the classification.
University of MississippiUniversity of CincinnatiTechnische Universitat DortmundUniversity of Pittsburgh logoUniversity of PittsburghUniversity of VictoriaINFN Sezione di NapoliUniversity of California, Santa Barbara logoUniversity of California, Santa BarbaraSLAC National Accelerator LaboratoryImperial College London logoImperial College LondonBudker Institute of Nuclear Physics SB RASUniversity of OklahomaUniversity of Manchester logoUniversity of ManchesterUniversity of Notre Dame logoUniversity of Notre DameTel Aviv University logoTel Aviv UniversityIndiana UniversityTechnische Universitat MunchenUniversity of California, Irvine logoUniversity of California, IrvineStanford University logoStanford UniversityOhio State UniversityMcGill University logoMcGill UniversityUniversity of Texas at Austin logoUniversity of Texas at AustinSouthern Methodist UniversityINFN Sezione di PisaRutherford Appleton LaboratoryUniversity of Maryland logoUniversity of MarylandColorado State UniversityUniversity of ColoradoLawrence Berkeley National Laboratory logoLawrence Berkeley National LaboratoryPurdue University logoPurdue UniversityUniversity of LiverpoolVirginia Tech logoVirginia TechPrinceton University logoPrinceton UniversityQueen Mary University of London logoQueen Mary University of LondonUniversity of Warwick logoUniversity of WarwickIowa State UniversityUniversity of LouisvilleUniversity of South CarolinaBrandeis UniversityUniversity of BergenBrunel UniversityINFN, Sezione di TorinoIndian Institute of Technology GuwahatiINFN, Laboratori Nazionali di FrascatiUniversity of California, Santa Cruz logoUniversity of California, Santa CruzUniversity of Hawai’iINFN, Sezione di MilanoUniversity of California RiversideINFN Sezione di PerugiaINFN - Sezione di PadovaINFN-Sezione di GenovaNikhef, National Institute for Subatomic PhysicsHumboldt-Universitat zu BerlinUniversite de MontrealJohannes Gutenberg Universit\"at MainzIFIC, Universitat de Valencia-CSICLAPP, Universit´e de Savoie, CNRS/IN2P3Institut f¨ur Experimentelle Kernphysik, Karlsruher Institut f¨ur Technologie (KIT)CEA, Irfu, SPP, Centre de SaclayLaboratoire de l’Acc´el´erateur Lin´eaire, IN2P3/CNRSLaboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole PolytechniqueGeorg-August-Universit¨at G¨ottingenAcademia Sinica, TaipeiCNRS-IN2P3, CPPMLudwig-Maximilians-Universität MünchenINFN-Sezione di FerraraInstituto de Física Corpuscular (IFIC), CSIC-Universitat de ValènciaINFN Sezione di Trieste
Dark sectors charged under a new Abelian force have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A'), connecting the dark sector to the Standard Model. We present a search for a dark photon in the reaction e+e- -> gamma A', A'-> e+e-, mu+mu- using 514 fb-1 of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the mixing strength between the photon and dark photon at the level of 10^-4 - 10^-3 for dark photon masses in the range 0.02 - 10.2 GeV. We further constrain the range of the parameter space favored by interpretations of the discrepancy between the calculated and measured anomalous magnetic moment of the muon.
Magnetoconvection at the solar surface governs the dynamics in the upper solar atmosphere and sustains the heliosphere. Properties of this fundamental process are poorly described near the solar poles. Here we report the first out-of-ecliptic remote-sensing observations of the south pole of the Sun from a high-latitude campaign of the Solar Orbiter spacecraft which reveal spatial and temporal evolution of supergranular convective cells. The supergranular cells have spatial scales of 20--40\,Mm. From eight days of observations starting on 2025 March 16, our analysis shows that the magnetic network migrates poleward, on average, at high latitudes (above 60\textdegree), with speeds in the range of 10--20\,m\,s1^{-1}, depending on the structures being tracked. These results shed light on the buildup of the polar magnetic field that is central to our understanding of the solar cycle and the heliospheric magnetic field.
It is established that for every pair of additive forms f=i=1saixik,g=i=1sbixikf=\sum_{i=1}^s a_i x_i^k, g=\sum_{i=1}^s b_i x_i^k of degree kk in s>2k2s>2k^2 variables the equations f=g=0f=g=0 have a non-trivial pp-adic solution for all odd primes pp.
We study tidal stripping of fuzzy dark matter (FDM) subhalo cores using simulations of the Schrödinger-Poisson equations and analyze the dynamics of tidal disruption, highlighting the differences with standard cold dark matter. Mass loss outside of the tidal radius forces the core to relax into a less compact configuration, lowering the tidal radius. As the characteristic radius of a solitonic core scales inversely with its mass, tidal stripping results in a runaway effect and rapid tidal disruption of the core once its central density drops below 4.54.5 times the average density of the host within the orbital radius. Additionally, we find that the core is deformed into a tidally locked ellipsoid with increasing eccentricities until it is completely disrupted. Using the core mass loss rate, we compute the minimum mass of cores that can survive several orbits for different FDM particle masses and compare it with observed masses of satellite galaxies in the Milky Way.
We show that in a system of one dimensional spinless fermions a topological phase and phase transition can emerge only through interaction. By allowing a dimerized or bond-alternating nearest neighbour interaction we show that the system exhibits a symmetry protected topological phase while its non-interacting limit is a gapless state. The non-trivial topological character appears due to the onset of two degenerate bond-order phases as a function of dimerized interaction which are found to be topologically distinct from each other. As a result a topological phase transition occurs between these bond order phases through a gap closing point. However, in the limit of strong interaction, the bond order phases are connected through a gapped charge density wave phase possessing local antiferromagnetic order. The topological nature is characterized by the edge states, Berry phase and non-local string order parameter. At the end we provide possible experimental signatures of the emergent symmetry protected topological phase transition in terms of Thouless charge pumping and density-density correlation.
We report results on studies of the e+e- annihilation into three-body Y(nS)pi+pi- (n=1,2,3) final states including measurements of cross sections and the full amplitude analysis. The cross sections measured at sqrt(s)=10.865 GeV and corrected for the initial state radiation are sigma(e+e-=>Y(1S)pi+pi-)=(2.27+-0.12+-0.14) pb, sigma(e+e-=>Y(2S)pi+pi-)=(4.07+-0.16+-0.45) pb, and sigma(e+e-=>Y(3S)pi+pi-)=(1.46+-0.09+-0.16) pb. Amplitude analysis of the three-body Y(nS)pi+pi- final states strongly favors I^G(J^P)=1^+(1^+) quantum-number assignments for the two bottomonium-like Zb+- states, recently observed in the Y(nS)pi+- and hb(mP)pi+- (m=1,2) decay channels. The results are obtained with a $121.4 1/fb data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider.
MICADO will enable the ELT to perform diffraction limited near-infrared observations at first light. The instrument's capabilities focus on imaging (including astrometric and high contrast) as well as single object spectroscopy. This contribution looks at how requirements from the observing modes have driven the instrument design and functionality. Using examples from specific science cases, and making use of the data simulation tool, an outline is presented of what we can expect the instrument to achieve.
We report the first observation of Y(5S) -> Y(nS) pi0 pi0 decays. The neutral partner of the Zb+-(10610), the Zb0(10610) decaying to Y(2,3S) pi0, is observed for the first time with a 6.5 sigma significance using a Dalitz analysis of Y(5S) -> Y(2,3S) pi0 pi0 decays. The results are obtained with a 121.4 fb^-1 data sample collected with the Belle detector at the Y(5S) resonance at the KEKB asymmetric-energy e+e- collider.
Generalization in robotics is one of the most important problems. New generalization approaches use internet databases in order to solve new tasks. Modern search engines can return a large amount of information according to a query within milliseconds. However, not all of the returned information is task relevant, partly due to the problem of polysemes. Here we specifically address the problem of object generalization by using image search. We suggest a bi-modal solution, combining visual and textual information, based on the observation that humans use additional linguistic cues to demarcate intended word meaning. We evaluate the quality of our approach by comparing it to human labelled data and find that, on average, our approach leads to improved results in comparison to Google searches, and that it can treat the problem of polysemes.
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We present a new library of synthetic spectra based on the stellar atmosphere code PHOENIX. It covers the wavelength range from 500Å to 55000Å with a resolution of R=500000 in the optical and near IR, R=100000 in the IR and {\Delta}{\lambda}=0.1Å in the UV. The parameter space covers 2300K<=Teff<=8000K, 0.0<=log(g)<=6.0, -4.0<=[Fe/H]<=+1.0 and -0.3<=[{\alpha}/Fe]<=+0.8. The library is work-in-progress and going to be extended to at least Teff=25000K. We use a new self-consistent way of describing the microturbulence for our model atmospheres. The entire library of synthetic spectra will be available for download. Futhermore we present a method for fitting spectra, especially designed to work with the new 2nd generation VLT instrument MUSE. We show that we can determine stellar parameters (Teff, log(g), [Fe/H] and [{\alpha}/Fe]) and even single element abundances.
We present NNLO QCD predictions for a wide range of event-shape observables in hadronic Higgs decays, taking into account the two dominant decay modes HggH\to gg and HbbˉH\to b\bar{b}. Specifically, we consider the six classical event shapes thrust, heavy jet mass, CC-parameter, total and wide jet broadening, and the three-jet resolution y23y_{23} in the Durham algorithm. We also present results for the soft-drop variant of thrust. Decays of the Higgs boson to two gluons are treated in the heavy-top limit, whereas decays to a bottom-quark pair are mediated by a non-vanishing Yukawa coupling, despite considering kinematically massless quarks. Our results highlight the importance of NNLO QCD corrections in the calculation of event-shape observables and provide means to quantify the intrinsic difference between the two Higgs decay modes.
Current theories of planetary evolution predict that infant giant planets have large radii and very low densities before they slowly contract to reach their final size after about several hundred million years. These theoretical expectations remain untested to date, despite the increasing number of exoplanetary discoveries, as the detection and characterisation of very young planets is extremely challenging due to the intense stellar activity of their host stars. However, the recent discoveries of young planetary transiting systems allow to place initial constraints on evolutionary models. With an estimated age of 20 million years, V1298\,Tau is one of the youngest solar-type stars known to host transiting planets: it harbours a multiple system composed of two Neptune-sized, one Saturn-sized, and one Jupiter-sized planets. Here we report the analysis of an intense radial velocity campaign, revealing the presence of two periodic signals compatible with the orbits of two of its planets. We find that planet b, with an orbital period of 24 days, has a mass of 0.64 Jupiter masses and a density similar to the giant planets of the Solar System and other known giant exoplanets with significantly older ages. Planet e, with an orbital period of 40 days, has a mass of 1.16 Jupiter masses and a density larger than most giant exoplanets. This is unexpected for planets at such a young age and suggests that some giant planets might evolve and contract faster than anticipated, thus challenging current models of planetary evolution.
Regression models describing the joint distribution of multivariate response variables conditional on covariate information have become an important aspect of contemporary regression analysis. However, a limitation of such models is that they often rely on rather simplistic assumptions, e.g. a constant dependency structure that is not allowed to vary with the covariates or the restriction to linear dependence between the responses only. We propose a general framework for multivariate conditional transformation models that overcomes these limitations and describes the entire distribution in a tractable and interpretable yet flexible way conditional on nonlinear effects of covariates. The framework can be embedded into likelihood-based inference, including results on asymptotic normality, and allows the dependence structure to vary with covariates. In addition, the framework scales well beyond bivariate response situations, which were the main focus of most earlier investigations. We illustrate the application of multivariate conditional transformation models in a trivariate analysis of childhood undernutrition and demonstrate empirically that our approach can be beneficial compared to existing benchmarks such that complex truly multivariate data-generating processes can be inferred from observations.
Hidden Markov models (HMMs) are characterized by an unobservable (hidden) Markov chain and an observable process, which is a noisy version of the hidden chain. Decoding the original signal (i.e., hidden chain) from the noisy observations is one of the main goals in nearly all HMM based data analyses. Existing decoding algorithms such as the Viterbi algorithm have computational complexity at best linear in the length of the observed sequence, and sub-quadratic in the size of the state space of the Markov chain. We present Quick Adaptive Ternary Segmentation (QATS), a divide-and-conquer procedure which decodes the hidden sequence in polylogarithmic computational complexity in the length of the sequence, and cubic in the size of the state space, hence particularly suited for large scale HMMs with relatively few states. The procedure also suggests an effective way of data storage as specific cumulative sums. In essence, the estimated sequence of states sequentially maximizes local likelihood scores among all local paths with at most three segments. The maximization is performed only approximately using an adaptive search procedure. The resulting sequence is admissible in the sense that all transitions occur with positive probability. To complement formal results justifying our approach, we present Monte-Carlo simulations which demonstrate the speedups provided by QATS in comparison to Viterbi, along with a precision analysis of the returned sequences. An implementation of QATS in C++ is provided in the R-package QATS and is available from GitHub.
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