Events
Particles and Fields Seminar
High-energy resummation effects in Heavy Quarkonium production physics
Maxim Nefedov
BGU
Mon, 02 Dec 2024, 14:00
Sacta-Rashi Building for Physics (54), room 207
Abstract: In the talk, an overview of inclusive heavy quarkonium production theory -- the Non-Relativistic QCD (NRQCD) factorisation, and corresponding phenomenology in proton-proton and electron-proton collisions will be given (see also the recent review [1] and the paper [2]). Then the resolution of perturbative instability of some observables in inclusive hadroproduction of eta-c mesons [3], inclusive photoproduction of J/psi [4] and exclusive photoproduction of J/psi [5] at NLO with the help of the resummation of high-energy logarithms in the hard process will be discussed. The continuation of this program beyond the Doubly-Logarithmic Approximation of Refs. [3,4,5] will be also mentioned if time permits (see [6,7]).
[1] D. Boer, C. A. Flett, C. Flore, D. Kikola, J. P. Lansberg, M. Nefedov, C. Van Hulse, S. Bhattacharya, J. Bor and M. Butenschoen, et al., ``Physics case for quarkonium studies at the Electron Ion Collider,'' arXiv:2409.03691 [hep-ph].
[2] N. Brambilla, M. Butenschoen and X. P. Wang, ``How well does nonrelativistic QCD factorization work at next-to-leading order?,'' arXiv:2411.16384 [hep-ph].
[3] J. P. Lansberg, M. Nefedov and M. A. Ozcelik, ``Matching next-to-leading-order and high-energy-resummed calculations of heavy-quarkonium-hadroproduction cross sections,'' JHEP 05, 083 (2022) [arXiv:2112.06789 [hep-ph]].
[4] J. P. Lansberg, M. Nefedov and M. A. Ozcelik, ``Curing the high-energy perturbative instability of vector-quarkonium-photoproduction cross sections at order $\alpha \alpha _s^3$ with high-energy factorisation,'' Eur. Phys. J. C 84, no.4, 351 (2024) [arXiv:2306.02425 [hep-ph]].
[5] C. A. Flett, J. P. Lansberg, S. Nabeebaccus, M. Nefedov, P. Sznajder and J. Wagner, ``Exclusive vector-quarkonium photoproduction at NLO in \alpha_s in collinear factorisation with evolution of the generalised parton distributions and high-energy resummation,'' Phys. Lett. B 859, 139117 (2024) [arXiv:2409.05738 [hep-ph]].
[6] M. Nefedov, ``One-loop impact factors for heavy quarkonium production: S-wave case,'' arXiv:2408.06234 [hep-ph].
[7] M. Nefedov, ``Forward eta_Q production impact factor at NLO,'' arXiv:2408.09440 [hep-ph].
Physics Colloquium
Travelling waves in our immune system
Prof. Ariel Amir
Weizmann Institute of Science
Tue, 03 Dec 2024, 12:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: In various biological scenarios, cells rely on the diffusion of signaling molecules to communicate, yet information needs to be communicated quickly and over large distances. How can the limitations of diffusion be surpassed? One solution Nature utilizes relies on "diffusive relays": upon sensing the signal, cells release more of it, thus creating an outgoing information wave. Mathematically, this mechanism manifests itself as an additional, non-linear, term in the diffusion equation, allowing for propagating wave solutions. The properties of these waves strongly depend on system dimensionality, and manifest intriguing phenomena, including regimes where wave velocity is independent of the diffusion constant. We recently proposed that such waves arise in the immune system, where upon sensing a signal, white blood cells known as neutrophils release a signaling molecule. However, in this case the waves must be self-extinguishing, since the range of cell recruitment must be limited. After introducing diffusive relays, I will discuss new mathematical models of self-extinguishing relays, and compare them to recent experiments on neutrophils.
Astrophysics and Cosmology Seminar
Applications of Fermilike energy gain mechanism for Photons in shearing plasma, (i) Limb brightening in AGN jets and (ii) Spectral lag transitions in GRBs
Dr. Mukesh Vyas
BIU
Wed, 04 Dec 2024, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: I will discuss new applications of the Fermilike energy gain mechanism for photons where a photon scatters with shearing layers of relativistic plasma and subsequently gains energy. The population of photons finally escapes from the photosphere of the system. Using structured jets that harbour velocity shear within them in extragalactic sources, I will describe two applications of this mechanism in this talk, (I) We present a unified theory of positive and negative spectral lags observed in the Gamma-Ray Bursts (GRBs) prompt phase. In positive lags, low-energy photons lag behind high-energy photons while the trend is the opposite in negative lags where high-energy photons arrive later. The model predicts a transition from positive to negative spectral lag which is commonly observed and remains unexplained in GRBs. (II) We demonstrate that the Compton scattering of photons with shearing plasma leads to a natural explanation for well-observed phenomena of Limb brightening in the Active Galactic Nuclei (AGNs) jet bases. In this phenomenon, the limb of the jet base appears brighter compared to its central axis. Our explanation lies in the relativistic nature of the optical depth in the shearing plasma. The investigation puts forward an unconventional picture of the existance of a Compton photosphere very close to jet base in AGNs.
Quantum optics seminar
Quantum technology with NV centers in diamonds
Dr. Amir Waxman
ELTA
Wed, 04 Dec 2024, 16:00
Zoom Only
Abstract: Zoom link: https://us02web.zoom.us/j/89482805771?pwd=kIs0oACgDkxfkzL7FVTFn6BapGbmOG.1
Abstract:
The coupling between nitrogen dopants and vacancies in the diamond lattice, generate a two level quantum system named NV centers (NVC), which is appealing to quantum technology applications due to its small size and the relative simplicity of the experimental setup. As a result, an intensive research has been conducted over the world for the last decades, suggesting its usage in the fields of quantum sensing, quantum information and quantum computing.
In this talk we focus on the work done by Elta, aiming to develop, based on NVC technology, both RF detectors and RF coherent sources.
Particles and Fields Seminar
Exposing hidden sectors
Yotam Soreq
Technion
Mon, 09 Dec 2024, 14:00
Sacta-Rashi Building for Physics (54), room 207
Abstract: Despite the huge success of the Standard Model of particle physics, it is not a complete description of Nature. It cannot account for several experimental results and observations and there are strong theoretical arguments that call for new physics. In this talk, we will discuss novel methods to hunt for new physics beyond the standard model at different energy and length scales, from atomic physics to future colliders.
Physics Colloquium
Hunting for Sub-GeV Dark Matter: From the SENSEI experiment to Oscura and Beyond
Prof. Erez Etzion
Tel-Aviv University
Tue, 10 Dec 2024, 12:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: This presentation will focus on the SENSEI experiments, the first to use Skipper-CCD technology to search for sub-GeV Dark Matter (DM). I will discuss recent results from SENSEI, showcasing our progress from initial prototypes to current findings at the underground SNOLAB facility. Additionally, I will introduce Oscura, a follow-up experiment that promises to expand our DM search capabilities significantly. Finally, I will touch on the DarkNESS mission, the first space initiative to utilize Skipper-CCD technology, which offers a unique perspective for DM exploration.
Biological and soft-matter physics
The sub-THz frequency behavior of human sweat ducts
Prof. Yuri Feldman
Applied Physics Department and Center of Electromagnetic Research and Characterization, The Hebrew University of Jerusalem
Thu, 12 Dec 2024, 12:00
Sacta-Rashi Building for Physics (54), room 207
Abstract: In the interaction of microwave radiation and human beings, the skin is traditionally considered as just an absorbing sponge stratum filled with water. This approach is justified when the impinging wavelength is greater than the dimensions of the skin layer. However, in the sub-THz band this condition is violated. In 2008, we demonstrated that the coiled portion of the sweat duct in upper skin layer could be regarded as an electromagnetic entity in the sub-THz band. The experiments linking the morphology of the eccrine sweat ducts to stress based variations in the reflection coefficient of the human palm, conducted in the frequency range of 75 GHz to 430 GHz. An intriguing finding in this experimental series was the demonstration of circular dichroism in the reflectance of the skin, significant because the helical structure of the sweat duct. We designed a simulation model that can provide us with both possibilities to study absorbance and emission of sub-THz radiation by Human Skin. Considering the helical duct as an electromagnetic entity, it dimensions dictate a characteristic frequency of absorption. The simulated frequency spectra qualitatively match the measured emission and reflected spectra.
All events
Google calendar
