321034 research outputs found
Sort by
Sparsity in the numerical six-point bootstrap - Novel extremal correlators in one dimension
No full textRecently, a qualitatively new class of rigorous bounds on CFT data was shown to be numerically computable from the crossing equations of six-point functions. However, this six-point bootstrap requires solving non-standard optimization problems involving infinite-dimensional matrices, which has limited its applicability and scalability in early implementations. In this talk, these challenges are overcome by exploiting the sparsity structure of the problem. The result is a reformulation into standard optimization problems already familiar in the conformal bootstrap and efficiently solvable with existing numerical tools. This insight makes the new bounds practically accessible. As an illustration, novel non-perturbative bounds whose extremal correlators interpolate between the six-point functions of the generalized free fermion and boson are discussed. These are compared with perturbative deformations of the massive free boson in AdS
How quantum computing can enhance biomarker discovery
No full textBiomarkers play a central role in medicine’s gradual progress toward proactive, personalized precision diagnostics and interventions. However, finding biomarkers that provide very early indicators of a change in health status, for example, for multifactorial diseases, has been challenging. The discovery of such biomarkers stands to benefit significantly from advanced information processing and means to detect complex correlations, which quantum computing offers. In this perspective, quantum algorithms, particularly in machine learning, are mapped to key applications in biomarker discovery. The opportunities and challenges associated with the algorithms and applications are discussed. The analysis is structured according to different data types—multidimensional, time series, and erroneous data—and covers key data modalities in healthcare—electronic health records, omics, and medical images. An outlook is provided concerning open research challenges. Precision medicine is a lofty goal, and challenges abound. A key ingredient to facilitate proactive interventions that keep an individual healthy is the detection of the earliest signals that the individual's health status is changing. Identification of such biomarkers requires advanced algorithms and analytics. Enter quantum computing. While still an emerging technology, quantum algorithms, particularly quantum machine learning, can uncover patterns that classical techniques cannot. This could enable the discovery of novel biomarkers and thus accelerate progress toward precision medicine. The authors discuss how quantum computing can improve biomarker discovery. This perspective highlights the application of quantum algorithms in analyzing complex healthcare data, including electronic health records, omics, and medical images, addresses the challenges of this technology, and provides an outlook on open research challenges in this field
Future Circular Collider Feasibility Study Report
No full textVolume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools/reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. The content and structure of this report are guided by the scope and priorities defined in the mandate of the FCC Feasibility Study. It is therefore not intended to serve as an exhaustive review of the full physics potential of FCC. Several topics, already covered in earlier reports such as the FCC CDR, are not reiterated here or are addressed only briefly, in alignment with the study’s focus. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the FCC programme
New Source for QCD Axion Dark Matter Production: Curvature Induced
No full textWe discuss a novel mechanism for generating dark matter from a fast-rolling scalar field, relevant for both inflation and rotating axion models, and apply it specifically to the (QCD) axion. Dark matter comes from scalar field fluctuations generated by the product of the curvature perturbation and the fast-rolling background field. These fluctuations can explain the totality of dark matter in a vast axion parameter space, particularly for the QCD axion, which will be targeted by upcoming experiments. We review the constraints on this mechanism and potential gravitational-wave signatures
Very high-energy gamma-ray detection and long-term multiwavelength view of the flaring blazar B2 1811+31
No full textContext. Among the blazars whose emission has been detected up to very high-energy (VHE; 100 GeV E<100 TeV) γ rays, intermediate synchrotron-peaked BL Lacs (IBLs) are quite rare. The IBL B2 1811+31 (z = 0.117) exhibited intense flaring activity in 2020. Detailed characterization of the source emission from radio to γ-ray energies was achieved with quasi-simultaneous observations, which led to the first-time detection of VHE γ-ray emission from the source with the MAGIC telescopes.Aims. In this work, we present a comprehensive multiwavelength (MWL) view of B2 1811+31, with a specific focus on the 2020 VHE flare, employing data from MAGIC, Fermi-LAT, Swift-XRT, Swift-UVOT, and several optical and radio ground-based telescopes.Methods. Long-term MWL data were employed to contextualize the high-state episode within the source emissions over 18 years. We investigated the variability, cross-correlations, and classification of the source emissions during low and high states. We propose an interpretative leptonic model for the observed radiative high state.Results. During the 2020 flaring state, the synchrotron peak frequency shifted to higher values and reached the limit of the IBL classification. Variability in timescales of a few hours in the high-energy (HE; 100 MeV<E<100 GeV) γ-ray band poses an upper limit of 6×1014 δD cm on the size of the emission region responsible for the γ-ray flare, with δD being the relativistic Doppler factor of the region. During the 2020 high state, the average spectrum became harder in the HE γ-ray band compared to the low states. A similar behavior has been observed in X-rays. Conversely, during different activity periods, we find harder-when-brighter trends in X-rays and a hint of softer-when-brighter trends at HE γ rays. A long-term HE γ-ray and optical correlation indicates that the same emission regions dominate the radiative output in both ranges, whereas the evolution at 15 GHz shows no correlation with the fluxes at higher frequencies. We test one-zone and two-zone synchrotron-self-Compton models for describing the broadband spectral energy distribution during the 2020 flaring state and investigate the self-consistency of the proposed scenario.Key words: radiation mechanisms: non-thermal / galaxies: active / BL Lacertae objects: individual: B2 1811+31 / gamma rays: general / X-rays: galaxie
Multiphysics Analysis of Cryogenically Cooled Photocathode in a CW SRF Injector cavity
No full textThe paper evaluates the thermal regime of a cryogenically cooled copper photocathode integrated into a continuous-wave superconducting radio-frequency injector cavity with direct thermal contact. Such a photoinjector layout is being developed at DESY and has recently demonstrated a record-high 50 MV/m axial electric field in radio-frequency tests, marking an important milestone. To address the thermal effect of the picosecond excitation laser, we first develop a two-temperature model to describe the temperature of the emitting surface at cryogenic temperatures and solve it numerically. Subsequently, we present a one-temperature model of the bulk photocathode coupled with an electromagnetic model of the injector cavity. For the current injector design, we predict a negligible impact of the laser on the intrinsic quality factor of the cavity, identifying instead the cryogenic stability of the copper cathode as the primary operational limit. To overcome cooling challenges, we propose an improved configuration of the cathode plug. For the proposed geometry, the multiphysics analysis confirms stable performance at a nominal 2 W laser power, sufficient for 100 pC beams at 1 MHz under optimistic quantum efficiency assumptions. Operation at higher laser loads will benefit from further dedicated cryogenic analysis
Generic Rolling Access at PETRA III
No full textPETRA III is a high-brilliance synchrotron radiation source operated by DESY in Hamburg, Germany, hosting 27 beamlines (two under construction) and nearly 60 experimental stations, which collectively provide research opportunities for academic users and commercial customers. The beamlines consistently experience overbooking, with only a limited number of requests for access being met based on scientific merit. Access to the facility is among the most important features. Beamtime allocation at PETRA III follows a biannual call-based model, similar to most synchrotron radiation facilities globally. Nonetheless, some challenges have been identified in the conventional call-based access model. Consequently, a new access model may be adapted to address the users’ demands
Proof-of-principle experiment for the dark-field detection concept for measuring vacuum birefringence
No full textVacuum fluctuations give rise to effective nonlinear interactions between electromagnetic fields. These generically modify the characteristics of light traversing a strong-field region. X-ray free-electron lasers (XFELs) constitute a particularly promising probe, due to their brilliance, the possibility of precise control and favorable frequency scaling. However, the nonlinear vacuum response is very small even when probing a tightly focused high-intensity laser field with XFEL radiation and direct measurement of light-by-light scattering of real photons and the associated fundamental physics constants of the quantum vacuum has not been possible to date. Achieving a sufficiently good signal-to-background separation is key to a successful quantum vacuum experiment. To master this challenge, a dark-field detection concept has recently been proposed. Here we present the results of a proof-of-principle experiment validating this approach by demonstrating that using real-world x-ray optics the background signal can be suppressed sufficiently to measure the weak nonlinear response of the vacuum
High Power Single Pass THz FEL in Operation at PITZ
No full textDevelopments on high power tunable THz source forpump-probe experiments at the European XFEL are ongoing atthe Photo Injector Test facility at DESY in Zeuthen (PITZ). ALCLS-I undulator is used for proof-of-principle experiments atPITZ. Narrow-band 3 THz pulses with pulse energy of~100 microjoules were generated in a single pass using 2-3 nC17 MeV electron bunches from the high brightness photo injector.First characterization results of the THz FEL at PITZ arereported
High Power Single Pass THz FEL in Operation at PITZ
No full textDevelopments on high power tunable THz source forpump-probe experiments at the European XFEL are ongoing atthe Photo Injector Test facility at DESY in Zeuthen (PITZ). ALCLS-I undulator is used for proof-of-principle experiments atPITZ. Narrow-band 3 THz pulses with pulse energy of~100 microjoules were generated in a single pass using 2-3 nC17 MeV electron bunches from the high brightness photo injector.First characterization results of the THz FEL at PITZ arereported