Tag Archives: Evento scientifico

Compressed dark sectors, with invisible decay products, are notoriously hard to probe at hadron colliders, particularly in the region of masses that are most relevant for thermal relics. Current search strategies rely mainly on hard radiation off the initial state. If the compressed sector contains an electrically-charged state, it is also possible to search for charged tracks that ‘disappear’ within the collider volume. A well-motivated example of a framework that contains such particles is the Minimal Supersymmetric Standard Model in the pure higgsino or wino limits. The current hadron-collider search strategy has no sensitivity to the upper range of pure higgsino masses that are consistent with the thermal relic density, even at a future circular collider (FCC) at 100~TeV centre-of-mass – the proper lifetime of its charged component, at around 10 picoseconds, is too short to be detected. In this seminar I will discuss what changes to analysis strategy and detector setup will be necessary to definitively discover or exclude the experimentally-elusive pure-higgsino thermal relic at the FCC, thus closing the window on neutralino dark matter.

Characterisation and exploiting properties of complex materials with high spatial resolution requires the deployment of multidisciplinary techniques and expertise. Soft X-ray microscopy, combining imaging and spectroscopy at sub-micron scales, has already been recognised as a powerful technique proving both morphological and chemical information. The TwinMic microscopy station [1] operated in the 400-2200 eV energy range at the Elettra synchrotron has been attracting different scientific community, from Life Sciences to Cultural Heritage and Material Science, thanks to its complementary imaging capabilities (brightfield and phase contrast) with spatial resolution down to sub 20nm with special CDI methods, combined with low energy X-ray Fluorescence (XRF) [2, 3] and X-ray absorption microspectroscopy. Unique feature is that the developed low energy XRF system enables monitoring light elements down to B. The presentation will use selected representative results to illustrate the recent achievements in the fields of neuroscience [4], nanotoxicology [5], clinical medicine [6,7], environmental science [8] and electrochemistry [9]. The progress in implementation of novel TwinMic imaging modalities for pushing the lateral resolution has recently been demonstrated by ptychography experiments with biological samples [10, 11]. Finally the first results of an on-going low energy XRF system development will be presented and discussed [12].

SISSI (Synchrotron Infrared Source for Spectroscopy and Imaging) is the infrared beamline at Elettra Sincrotrone Trieste. It extracts the IR and visible components of synchrotron emission for performing spectroscopy, microspectroscopy and imaging at the two SISSI branches: SISSI-Mat (IOM-CNR, Sapienza) and SISSI-Bio (Elettra). The applications cover a wide range of research fields, including surface and material science, high-pressure experiments, geology, cultural heritage, biochemistry, cellular biology, etc. The present talk aims to provide an overview of the actual beamline status, focusing on the equipment and potentialities of SISSI-Bio branchline. Selected examples of both user and in-house research activities at SISSI-Bio will be presented, covering fields of science such as in-situ cell sorting according to cell-cycle phases by FTIR microscopy and X-ray radiation damage probed by non-damaging IR beams. An overview of the planned upgrades of SISSI will be also provided, in order to explore potential synergisms with LNF, encompassing both technical developments and scientific topics. LISA VACCARI1 AND GIOVANNI BIRARDA1 1) Elettra Sincrotrone Trieste, SS 14 Km 143.5 34149 Trieste, ITALY

Imaging techniques based on the use of hard X-rays play an important role in several research fields and industrial applications. Many topics in medicine, biology, material science, geosciences and cultural heritage studies can be afforded thanks to the high potential and large applicability of X-ray imaging. In the last twenty years a great interest has been devoted to the development of X-ray computed microtomography (micro-CT) techniques, both employing microfocus and synchrotron radiation sources. These techniques allows to produce 3D or 4D (dynamic micro-CT) images of the internal structure of objects at the micron- and submicron- scale. Investigations performed directly in the 3D domain overcome the limitations of stereological methods usually applied to microscopy-based analyses and a non-destructive method is more suitable for further complementary analyses and for precious or unique samples (fossils and archeological finds, in-vivo imaging, etc …). An intriguing challenge is to extract directly from 3D and 4D images quantitative parameters related to the physical properties of the studied materials. However, accurate image processing, analysis and visualization methods for an effective assessment of these parameters are still an open issue especially in the case of 4D micro-CT experiments. In this talk, several scientific applications of advanced hard X-ray imaging techniques will be presented trying to critically expose advantages, limitations and open problems in the different fields.

The workshop OPTICS – Outlook and Proposal for Technological & Innovative Cooperation Strategies has been planned within the international seminar "Advanced Accelerator & Radiation Physics" (LNF-MEPhI), which represents a series of the meetings dedicated to frontier topics in basic and applied research associated to new techniques of beam acceleration, novel powerful radiation sources and applications based on radiation physics. The AARP: OPTICS workshop will be focused on the presentation of main activities and research projects of three beamlines of Elettra-Sincrotrone Trieste (SYRMEP, SISSI,  TwinMic) as well as two INFN LNF laboratories (Dafne-Light Lab, XLab_Frascati). The workshop is the opportunity for pointing out common interests in the field of novel x-ray sources, optics, detectors and various x-ray applications that aims in identifying new possible collaborations.  

The RVP method in principle allows to obtain the analytic continuation of a function that is only given in numerical form. It only requires real input in order to reconstruct the underlying function not only along the real axis but also in the complex plane. It is applied to experimental data in order to locate complex resonance poles as well as decay thresholds. Moreover, it is applied to numerical data on Euclidean (imaginary-time) data in order to obtain the real-time propagator and the corresponding spectral function. This procedure in principle represents an alternative to techniques like the Maximum Entropy Method (MEM) and to inverting the associated Laplace transform. (https://arxiv.org/abs/1610.03252)

We present our recent study of gluon spectra in lattice QCD at finite temperature [1]. In it we combine recent full QCD simulations with Nf=2+1+1 twisted mass flavors carried out by the tmft collaboration [2] with a novel Bayesian approach [3] to the reconstruction of general spectral functions. This method is directly applicable to gluon correlation functions fixed to Landau gauge, whose spectra exhibit positivity violation. In these spectra we observe the presence of a well defined quasi-particle peak at all investigated temperatures, which provides the means to extract a gluon dispersion relation. The corresponding in-medium gluon masses defined from its zero momentum limit are shown to exhibit a behavior qualitatively consistent with weak coupling expectations. [1] E.-M. Ilgenfritz, Jan M. Pawlowski, A.R., A. Trunin arXiv:1701.08610 [2] F. Burger et. al. (tmft Collaboration) arXiv:1510.02262 [3] A.R. arXiv:1611.00482

In this talk I will introduce a rather recent scaling method allowing to perform the usual equilibrium finite-size scaling analysis for continuous phase transitions in the out-of-equilibrium relaxation regime. Such an approach is most valuable for all those system which show a very slow critical dynamics – i.e. a high value of the dynamic exponent z – and systems which are computationally expensive to simulate. I will show results obtained for the three-dimensional IsingSpin Glass (z ~ 6.8) relaxed via the Metropolis dissipative dynamics. The values of the critical exponents and critical temperature are the first out-of-equilibrium estimates to be compatible and comparable in precision with those obtained from the "Janus" dedicated supercomputer. Since the method is based on Renormalization Group arguments it turns out to be completely general and, potentially, of wide interest in different domains. Furthermore, I will summarize some results obtained in the development of the numerical implementation of such simulations optimized for GPU architectures. [1] M. Lulli, G. Parisi and A. Pelissetto, PRE 93, 032126 [1](2016), http://dx.doi.org/10.1103/PhysRevE.93.032126 [2] [2] M. Lulli, M. Bernaschi and G. Parisi, CPC 196 (2015) 290–303, http://dx.doi.org/10.1016/j.cpc.2015.06.019 [3]

We derive mass formulae for broken(and unbroken) supersymmetry in curved space-time. These formulae are applicable to De-Sitter configurations as in the case of inflation. For unbroken supersymmetry in Anti-de-Sitter they describe the deviation from flat space formulae due to the space-time curvature.

The investigation of Higgs boson properties is one of the most important activities in particle physics nowadays. Such studies can provide invaluable insights on the nature of beyond the Standard Model physics, complementing the ongoing direct searches. The increasing precision of the experimental measurements at the LHC calls for correspondingly good theoretical predictions for Higgs production processes. In this context, calculations of QCD corrections to the production rates for these processes are of central relevance to the LHC physics programme. A major contribution to higher order QCD corrections originates from multiple soft gluon emission and can be treated systematically to all orders by means of resummation techniques. In this talk I will review the application of resummation techniques to Higgs boson physics at the LHC, concentrating on the processes of the associated Higgs production.