Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEvent generation for beam dump experiments
307
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
A wealth of new physics models which are motivated by questions such as the nature of dark matter, the origin of the neutrino masses and the baryon asymmetry in the universe, predict the existence of hidden sectors featuring new particles. Among the possibilities are heavy neutral leptons, vectors and scalars, that feebly interact with the Standard Model (SM) sector and are typically light and long lived. Such new states could be produced in high-intensity facilities, the so-called beam dump experiments, either directly in the hard interaction or as a decay product of heavier mesons. They could then decay back to the SM or to hidden sector particles, giving rise to peculiar decay or interaction signatures in a far-placed detector. Simulating such kind of events presents a challenge, as not only short-distance new physics (hard production, hadron decays, and interaction with the detector) and usual SM phenomena need to be described but also the travel has to be accounted for as determined by the geometry of the detector. In this work, we describe a new plugin to the {sc MadGraph5_aMC@NLO} platform, which allows the complete simulation of new physics processes relevant for beam dump experiments, including the various mechanisms for the production of hidden particles, namely their decays or scattering off SM particles, as well as their far detection, keeping into account spatial correlations and the geometry of the experiment.
rate research
Read More
Positrons beam dump experiments have unique features to search for very narrow resonances coupled superweakly to $e^+ e^-$ pairs. Due to the continue loss of energy from soft photon bremsstrahlung, in the first few radiation lengths of the dump a positron beam can continuously scan for resonant production of new resonances via $e^+$ annihilation off an atomic $e^-$ in the target. In the case of a dark photon $A$ kinetically mixed with the photon, this production mode is of first order in the electromagnetic coupling $alpha$, and thus parametrically enhanced with respect to the $O(alpha^2)$ $e^+e^- to gamma A$ production mode and to the $O(alpha^3)$ $A$ bremsstrahlung in $e^--$nucleon scattering so far considered. If the lifetime is sufficiently long to allow the $A$ to exit the dump, $A to e^+e^-$ decays could be easily detected and distinguished from backgrounds. We explore the foreseeable sensitivity of the Frascati PADME experiment in searching with this technique for the $17,$MeV dark photon invoked to explain the $^8$Be anomaly in nuclear transitions.
We consider the light $Z$ explanation of the muon $g-2$ anomaly. Even if such a $Z$ has no tree-level coupling to electrons, in general one will be induced at loop-level. We show that future beam dump experiments are powerful enough to place stringent constraints on$-$or discover$-$a $Z$ with loop-suppressed couplings to electrons. Such bounds are avoided only if the $Z$ has a large interaction with neutrinos, in which case the scenario will be bounded by ongoing neutrino scattering experiments. The complementarity between beam dump and neutrino scattering experiments therefore indicates that there are good prospects of probing a large part of the $Z$ parameter space in the near future.
There are broadly three channels to probe axion-like particles (ALPs) produced in the laboratory: through their subsequent decay to Standard Model (SM) particles, their scattering with SM particles, or their subsequent conversion to photons. Decay and scattering are the most commonly explored channels in beam-dump type experiments, while conversion has typically been utilized by light-shining-through-wall (LSW) experiments. A new class of experiments, dubbed PASSAT (Particle Accelerator helioScopes for Slim Axion-like-particle deTection), has been proposed to make use of the ALP-to-photon conversion in a novel way: ALPs, after being produced in a beam-dump setup, turn into photons in a magnetic field placed near the source. It has been shown that such hybrid beam-dump-helioscope experiments can probe regions of parameter space that have not been investigated by other laboratory-based experiments, hence providing complementary information; in particular, they probe a fundamentally different region than decay or LSW experiments. We propose the implementation of PASSAT in future neutrino experiments, taking a DUNE-like experiment as an example. We demonstrate that the magnetic field in the planned DUNE multi-purpose detector is already capable of probing the ALP-photon coupling down to $g_{agammagamma} sim {rm few}times 10^{-5}$ GeV$^{-1}$ for ALP masses $m_a lesssim 10$ eV. The implementation of a CAST or BabyIAXO-like magnet would improve the sensitivity down to $g_{agammagamma} sim 10^{-6}$ GeV$^{-1}$.
We perform a feasibility study of a beam dump experiment at the International Linear Collider (ILC). To investigate the sensitivity to new light particles at the experiment, we consider models for axion-like particles (ALPs) and a light scalar particle coupled to charged leptons. For both models, we show that the detection sensitivity is almost an order of magnitude higher than other beam dump experiments in the small coupling region. For ALPs, it is shown that the ILC beam dump experiment is highly complementary to bounds from astrophysics. In addition, for the model of the scalar particle, the region favored by the muon $g-2$ experiment can be explored.
High energy positron annihilation is a viable mechanism to produce dark photons ($A^prime$). This reaction plays a significant role in beam-dump experiments using experiments using multi-GeV electron-beams on thick targets by enhancing the sensitivity to $A^prime$ production. The positrons produced by the electromagnetic shower can produce an $A^prime$ via non-resonant ($e^+ + e^- to gamma + A^prime$) and resonant ($e^+ + e^- to A^prime$) annihilation on atomic electrons. For visible decays, the contribution of resonant annihilation results in a larger sensitivity with respect to limits derived by the commonly used $A^prime$-strahlung in certain kinematic regions. When included in the evaluation of the E137 beam-dump experiment reach, positron annihilation pushes the current limit on $varepsilon$ downwards by a factor of two in the range 33 MeV/c$^2<m_{A^prime}<120$ MeV/c$^2$.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
