Passage of millicharged particles in the electron beam-dump: refining constraints from SLACmQ and estimating sensitivity of NA64e

Millicharged particles (MCPs) arise in many well-motivated extensions of the Standard Model and are a popular subject for experimental searches. We investigate attenuation of the MCP flux produced at accelerator experiments due to their interactions in the media. Considering, as an example, the dedicated MCP search at SLACmQ, we demonstrate that this effect can significantly affect the final sensitivity to the MCP parameter space leaving its essential part still unexplored. Applying our analysis to the SLACmQ experiment [53], we correct their exclusion bounds in close accordance with Ref. [54]. We also show that this newly reopened area with the MCP masses in the range $10^{-4}$ eV - $1$ GeV and charges $\gtrsim 10^{-5} e$ can be effectively probed by the NA64$e$ experiment at the CERN SPS. Light MCPs are mostly produced by virtual photon in electron scattering off nucleus. The main source of heavy MCP is decays of vector mesons, produced by the electrons on nuclei.Comment: 26 pages, 15 figures, typos in acknowledgements are corrected, clarification for the revised SLACmQ curve is adde

Light-shining-through-wall cavity setups for probing ALPs

We discuss the aspects of axion-like-particles (ALPs) searches with Light-Shining-through-Wall (LSW) experimental setups consisted of two radio-frequency cavities. We compare the efficiencies of three setups which involve the cavity pump modes and external magnetic fields. Additionally, we discuss the sensitivity dependence both on the relative position of two cylindrical cavities and on their radius-to-length ratio.Comment: 9 pages, 6 figures, 1 table. Revised version, accepted to JETP Letter

Implication of the dark axion portal for the EDM of fermions and dark matter probing with NA64ee, NA64μ\mu, LDMX, \mbox{M}^3, and BaBar

The link between ordinary Standard model (SM) photon and both dark photon and axion like particle (ALP) can be introduced through the dark axion portal coupling. Given the dark axion portal setup, in the present paper we refer the dark photon as the mediator between SM and dark matter (DM) particles, implying that it decays predominantly into pair of DM fermions. Furthermore, we discuss in detail the implication of the dark axion portal scenario for the lepton (electron and muon) fixed target experiments. In particular, for the specific fixed target facility we study the missing energy signatures of the dark photon production followed by its invisible decay into stable DM particles. We investigated the potential to probe dark axion portal vertices with regarding signatures and derive the expected sensitivities of NA64$e$, NA64$\mu$, LDMX and \mbox{M}^3. Moreover, we estimated the expected reach of NA64$e$ from the projected statistics of the $J/\psi$ vector meson invisible decays. We also recasted BaBar monophoton bounds for the specific dark axion portal scenario. In addition, we modified the dark axion portal setup by including in the model both the hadron and lepton specific ALP couplings. As the result, we obtain the bounds on the combination of fermion-specific couplings of ALP from the fixed target experiments. We discuss the implication of the modified dark axion portal scenario for the electric dipole moments (EDM) of SM fermions. In addition, we derived the novel constraints on the combination of the $CP$-violating neutron-specific ALP couplings from the existing bounds on neutron EDM by taking into account the neutron anomalous magnetic moment.Comment: 17 pages, 15 figure

Lepton flavor violating dark photon

We study possible impact of dark photons on lepton flavor phenomenology. We derive the constraints on non-diagonal dark photon couplings with leptons by analyzing corresponding contributions to lepton anomalous magnetic moments, rare lepton decays and the prospects of fixed-target experiments aiming for search for light dark matter based on missing energy/momentum techniques.Comment: 9 pages, 9 Fig

Probing invisible vector meson decay mode with hadronic beam in the NA64 experiment at SPS/CERN

We test a novel idea of using a $\pi^-$ beam in the fixed-target experiments to search for New Physics in the events with missing energy. Bounds for invisible vector $\rho$ meson decay were derived, analyzed, and compared with the current limits on searching Dark Matter in the accelerator based experiments. We demonstrate that the new approach can be effective tool to probe sub-GeV Dark Matter parameter space.Comment: 8 pages,, 5 figures and 1 Tabl

Cytotoxicity of albebetin oligomers depends on cross-β-sheet formation

AbstractPrefibrillar cytotoxicity was suggested as a common amyloid characteristic. We showed two types of albebetin prefibrillar oligomers are formed during incubation at pH 7.3. Initial round-shaped oligomers consist of 10–15 molecules determined by atomic force microscopy, do not bind thioflavin-T and do not affect viability of granular neurons and SH-SY5Y cells. They are converted into ca. 30–40-mers possessing cross-β-sheet and reducing viability of neuronal cells. Neither monomers nor fibrils possess cytotoxicity. We suggest that oligomeric size is important for stabilising cross-β-sheet core critical for cytotoxicity. As albebetin was used as a carrier-protein for drug delivery, examination of amyloidogenicity is required prior polypeptide biomedical applications

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe