More Like this

1. Unleashing the full power of LHCb to probe stealth new physics

   Borsato, M ; Cid Vidal, X ; Tsai, Y ; Vázquez Sierra, C ; Zurita, J ; Alonso-Álvarez, G ; Boyarsky, A ; Brea Rodríguez, A ; Buarque Franzosi, D ; Cacciapaglia, G ; et al ( February 2022 , Reports on Progress in Physics)

   Abstract In this paper, we describe the potential of the LHCb experiment to detect stealth physics. This refers to dynamics beyond the standard model that would elude searches that focus on energetic objects or precision measurements of known processes. Stealth signatures include long-lived particles and light resonances that are produced very rarely or together with overwhelming backgrounds. We will discuss why LHCb is equipped to discover this kind of physics at the Large Hadron Collider and provide examples of well-motivated theoretical models that can be probed with great detail at the experiment. 

   more » « less
2. Expression of interest for the CODEX-b detector

   https://doi.org/10.1140/epjc/s10052-020-08711-3  

   Aielli, Giulio ; Ben-Haim, Eli ; Cardarelli, Roberto ; Charles, Matthew John ; Cid Vidal, Xabier ; Coco, Victor ; Dey, Biplab ; Dumps, Raphael ; Evans, Jared A. ; Gibbons, George ; et al ( December 2020 , The European Physical Journal C)

   null (Ed.)

   Abstract This document presents the physics case and ancillary studies for the proposed CODEX-b long-lived particle (LLP) detector, as well as for a smaller proof-of-concept demonstrator detector, CODEX- $$\beta $$ β , to be operated during Run 3 of the LHC. Our development of the CODEX-b physics case synthesizes ‘top-down’ and ‘bottom-up’ theoretical approaches, providing a detailed survey of both minimal and complete models featuring LLPs. Several of these models have not been studied previously, and for some others we amend studies from previous literature: In particular, for gluon and fermion-coupled axion-like particles. We moreover present updated simulations of expected backgrounds in CODEX-b’s actively shielded environment, including the effects of shielding propagation uncertainties, high-energy tails and variation in the shielding design. Initial results are also included from a background measurement and calibration campaign. A design overview is presented for the CODEX- $$\beta $$ β demonstrator detector, which will enable background calibration and detector design studies. Finally, we lay out brief studies of various design drivers of the CODEX-b experiment and potential extensions of the baseline design, including the physics case for a calorimeter element, precision timing, event tagging within LHCb, and precision low-momentum tracking. 

   more » « less
3. FASER’s Electromagnetic Calorimeter Test Beam Studies

   https://doi.org/10.3390/instruments6030031  

   Cavanagh, Charlotte ( September 2022 , Instruments)

   FASER, or the Forward Search Experiment, is a new experiment at CERN designed to complement the LHC’s ongoing physics program, extending its discovery potential to light and weakly interacting particles that may be produced copiously at the LHC in the far-forward region. New particles targeted by FASER, such as long-lived dark photons or axion-like particles, are characterised by a signature with two oppositely charged tracks or two photons in the multi-TeV range that emanate from a common vertex inside the detector. The full detector was successfully installed in March 2021 in an LHC side tunnel 480 m downstream from the interaction point in the ATLAS detector. FASER is planned to be operational for LHC Run 3. The experiment is composed of a silicon-strip tracking-based spectrometer using three dipole magnets with a 20 cm aperture, supplemented by four scintillator stations and an electromagnetic calorimeter. The FASER electromagnetic calorimeter is constructed from four spare LHCb calorimeter modules. The modules are of the Shashlik type with interleaved scintillator and lead plates that result in 25 radiation lengths and 1% energy resolution for TeV electromagnetic showers. In 2021, a test beam campaign was carried out using one of the CERN SPS beam lines to set up the calibration of the FASER calorimeter system in preparation for physics data taking. The relative calorimeter response to electrons with energies between 10 and 300 GeV, as well as high energy muons and pions, has been measured under various high voltage settings and beam positions. The measured calorimeter resolution, energy calibration, and particle identification capabilities are presented. 

   more » « less
4. Maximizing learning without sacrificing the fun: Stealth assessment, adaptivity and learning supports in educational games

   https://doi.org/10.1111/jcal.12473  

   Shute, Valerie ; Rahimi, Seyedahmad ; Smith, Ginny ; Ke, Fengfeng ; Almond, Russell ; Dai, Chih‐Pu ; Kuba, Renata ; Liu, Zhichun ; Yang, Xiaotong ; Sun, Chen ( July 2020 , Journal of Computer Assisted Learning)

   In this study, we investigated the validity of a stealth assessment of physics understanding in an educational game, as well as the effectiveness of different game‐level delivery methods and various in‐game supports on learning. Using a game calledPhysics Playground, we randomly assigned 263 ninth‐ to eleventh‐grade students into four groups: adaptive, linear, free choice and no‐treatment control. Each condition had access to the same in‐game learning supports during gameplay. Results showed that: (a) the stealth assessment estimates of physics understanding were valid—significantly correlating with the external physics test scores; (b) there was no significant effect of game‐level delivery method on students' learning; and (c) physics animations were the most effective (among eight supports tested) in predicting both learning outcome and in‐game performance (e.g. number of game levels solved). We included student enjoyment, gender and ethnicity in our analyses as moderators to further investigate the research questions.

    

   more » « less
5. Predicting the Magnetic Fields of a Stealth CME Detected by Parker Solar Probe at 0.5 au

   https://doi.org/10.3847/1538-4357/ac25f4  

   Palmerio, Erika ; Kay, Christina ; Al-Haddad, Nada ; Lynch, Benjamin J. ; Yu, Wenyuan ; Stevens, Michael L. ; Pal, Sanchita ; Lee, Christina O. ( October 2021 , The Astrophysical Journal)

   Stealth coronal mass ejections (CMEs) are eruptions from the Sun that are not associated with appreciable low-coronal signatures. Because they often cannot be linked to a well-defined source region on the Sun, analysis of their initial magnetic configuration and eruption dynamics is particularly problematic. In this article, we address this issue by undertaking the first attempt at predicting the magnetic fields of a stealth CME that erupted in 2020 June from the Earth-facing Sun. We estimate its source region with the aid of off-limb observations from a secondary viewpoint and photospheric magnetic field extrapolations. We then employ the Open Solar Physics Rapid Ensemble Information modeling suite to evaluate its early evolution and forward model its magnetic fields up to Parker Solar Probe, which detected the CME in situ at a heliocentric distance of 0.5 au. We compare our hindcast prediction with in situ measurements and a set of flux-rope reconstructions, obtaining encouraging agreement on arrival time, spacecraft-crossing location, and magnetic field profiles. This work represents a first step toward reliable understanding and forecasting of the magnetic configuration of stealth CMEs and slow streamer-blowout events.

    

   more » « less