scispace - formally typeset
Search or ask a question

Showing papers in "Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields in 2018"



Journal ArticleDOI
TL;DR: In this article, the authors discuss a scenario where the dark matter abundance is controlled by a "vev flipflop", which sets the relic abundance via a period of dark matter decay just before electroweak symmetry breaking.
Abstract: — Thermal freeze-out of a weakly interacting massive particle is the dominant paradigm for dark matter production. This scenario is now being probed by direct and indirect detection experiments, as well as at colliders. The lack of convincing signals motivates us to consider alternative scenarios. In this contribution we discuss a scenario where the dark matter abundance is controlled by a “vev flipflop”, which sets the relic abundance via a period of dark matter decay just before electroweak symmetry breaking. We describe the mechanism and show that it is successful in a wide range of parameter space before discussing detection possibilities.

4 citations


Journal ArticleDOI
TL;DR: The PADME experiment as mentioned in this paper is designed to search for the e+e− → γA process in a positron-on-target experiment, assuming a decay of the A into invisible particles of the hidden sector.
Abstract: — Massive photon-like particles are predicted in many extensions of the Standard Model with a hidden sector accounting for dark matter candidates. They have interactions similar to the photon, are vector bosons, and can be produced together with photons. Most of the present experimental constraints on the dark photon (A) rely on the hypothesis of dominant decays to lepton pairs. The PADME experiment aims at searching for the e+e− → γA process in a positron-on-target experiment, assuming a decay of the A into invisible particles of the hidden sector. The positron beam of the DAΦNE Beam-Test Facility (BTF), produced by the LINAC at the Laboratori Nazionali di Frascati of INFN, will be used. The core of the experimental apparatus is a fine-grained, high-resolution calorimeter. It will measure with high precision the momentum of the photon in events with no other activity in the detector, thus allowing to measure the A mass as the missing mass in the final state. In about one year data taking, a sensitivity on the interaction strength ( 2 parameter) down to 10−6 is achievable, in the mass region from 1 MeV < MA < 23.7 MeV, running with 6000 positrons in 40 ns long bunches at 550 MeV beam energy. The experiment, now in the construction phase, is planned to run in 2018. The status of the PADME detector and the physics potential of PADME is reviewed.

2 citations




Journal ArticleDOI
TL;DR: In this article, the authors have proposed the use of Thick-GEM (THGEM) technology in the field of cryogenic detectors, in particular for double-phase large volume Ar ones are proposed.
Abstract: Thick-GEMs (THGEMs) are simple and robust gaseous multipliers, derived from the GEM design and proposed for large-scale applications. Classical THGEMs consist of Printed Circuit Boards (PCBs) with a regular pattern of holes obtained by drilling; they are manufactured by industry in large series and large size; their response for different geometrical parameters and operational conditions has been extensively studied. Different substrates (ceramic, glass, PTFE, etc.) and various production procedures have also been investigated with promising results. Different design options, like highly segmented electrodes, and different architectures, in particular those based on the Thick-WELL design are being actively studied. THGEMs are used as gaseous multipliers and as reflective photocathodes for VUV photons when coated with a CsI layer. THGEM-based Photon Detectors have been successfully implemented in 2016 on COMPASS RICH-1 for a total active area of 1.4 m2. Applications of THGEM (also called LEM) technology in the field of cryogenic detectors, in particular for double-phase large volume Ar ones are proposed. The recently discovered phenomenon of bubble assisted electro-luminescence in liquid Xe opens the way to local dual phase cryogenic detector configurations when using THGEMs. The detection of X-rays and neutrons using THGEM-based devices is a very active field. Promising results have been obtained using THGEMs for imaging applications.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the sensitivity of the lightest supersymmetric particle (LSP) for the dark matter (DM) in the universe and compared it with the expected sensitivity of future direct direct DM experiments.
Abstract: — In the next to minimal supersymmetric standard model (NMSSM) the lightest supersymmetric particle (LSP) is a candidate for the dark matter (DM) in the universe. It is a mixture from the various gauginos and Higgsinos and can be bino-, Higgsinoor singlino-dominated. These different scenarios are investigated in detail and compared with the sensitivity of future direct DM experiments, where we use an efficient sampling technique of the parameter space. We find that LSPs with a significant amount of Higgsino and bino admixture will have cross sections in reach of future direct DM experiments, so the background from coherent neutrino scattering is not yet limiting the sensitivity. Both the spin-dependent (SD) and spinindependent (SI) searches are important, depending on the dominant admixture. If the predicted relic density is too low, additional DM candidates are needed, in which case the LSP direct DM searches loose sensitivity of the reduced LSP density. This is taken into account for expected sensitivity. The singlino-like LSP has regions of parameter space with cross sections below the “neutrino floor”. In this region the background from coherent neutrino scattering is expected to be too high, in which case the NMSSM DM will evade discovery via direct detection experiments.

Journal ArticleDOI
TL;DR: In this paper, the authors review physics and technology drivers that could suggest how to proceed in the choice of the next big accelerator and make important decisions soon to secure the continuation of this line of research after the HL-LHC program has been completed.
Abstract: — The Higgs boson discovery has been a major success of high energy physics, yet it gives us little guidance on how to best invest for future research facilities. It is however urgent to make important decisions soon to secure the continuation of this line of research after the HL-LHC program has been completed. We review physics and technology drivers that could suggest how to proceed in the choice of the next big accelerator.