Searches for light new physics at BABAR

B-factories are ideal machines to probe for light New Physics, thanks to their high luminosities and low background environments. In the following, we report recent searches for a light Higgs boson, lepton universality violation and dark matter candidates performed with the BABAR detector. No evidence for physics beyond the Standard Model is observed and constraints on the existence of these new particles are derived

Reach and complementarity of μ→e\mu\to e searches

In Effective Field Theory, we describe $\mu\leftrightarrow e$ flavour changing transitions using an operator basis motivated by experimental observables. In a six-dimensional subspace probed by $\mu \to e \gamma$, $\mu \to 3e$ and $\mu\to e$ conversion on nuclei, we derive constraints on the New Physics scale from past and future experiments, illustrating the complementarity of the processes in an intuitive way. We also recall that a precise determination of the scalar quark currents in the nucleon will be required to distinguish scalar $\mu\to e$ interactions on u-quarks from those on d-quarks.Comment: 10 pages, 7 figures, + 5 pages appendice

Stable Colored Particles R-SUSY Relics or Not?

R-hadrons are only one of many possible stable colored states that the LHC might produce. All such particles would provide a spectacular, if somewhat unusual, signal at ATLAS and CMS. Produced in large numbers and leaving a characteristic signature throughout all layers of the detector, including the muon chamber, they could be straightforward to discover even with low luminosity. Though such long lived colored particles (LLCPs) can be realized in many extensions of the Standard Model, most analyses of their phenomenology have focused only on R-hadrons. In order to distinguish among the possibilities, fundamental quantum numbers of the new states must be measured. In this paper, we demonstrate how to identify the $SU(3)_C$ charge and spin of such new particles at the LHC.Comment: 11 pages, 7 figure

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017

Search for dark photon production at BaBar

We present a search for a dark photon, a new massive vector boson interacting weakly with Standard Model particles, using data collected with the BaBar detector. No statistically significant deviations from the Standard Model predictions are seen, and 90% confidence level upper limits on the mixing strength between the photon and dark photon are set at the level of 10^(-4)–10^(-3) for dark photon masses in the range 0.02 – 10.2 GeV

Projections for Dark Photon Searches at Mu3e

We show that dark photons (A') with masses ~10-80 MeV can be probed in the decay $\mu^+ \to e^+ \nu_e \bar{\nu}_\mu A', A' \to e^+ e^-$, with the upcoming Mu3e experiment at the Paul Scherrer Institute (PSI) in Switzerland. With an expected 10^{15} (5.5 x 10^{16}) muon decays in 2015-2016 (2018 and beyond), Mu3e has the exciting opportunity to probe a substantial fraction of currently unexplored dark photon parameter space, probing kinetic-mixing parameter, epsilon, as low as epsilon^2 ~ 10^{-7} (10^{-8}). No modifications of the existing Mu3e setup are required.Comment: 9 pages, 7 figures; typos corrected, references adde

Probing the Dark Sector with Dark Matter Bound States

A model of dark sector where O(few GeV) mass dark matter particles χ are supplied by a lighter dark force mediator V, m_V ≪ m_χ, is motivated by the recently discovered mismatch between simulated and observed shapes of galactic haloes. Such models, in general, provide a challenge for direct detection efforts and collider searches. We show that for a large range of coupling constants and masses, the production and decay of the bound states of χ, such as 0^(−+) and 1^(−−) states, η_D and Υ_D, is an important search channel. We show that e+e− → η_D + V or Υ_D + γ production at B-factories for α_D > 0.1 is sufficiently strong to result in multiple pairs of charged leptons and pions via η_D → 2V → 2(l^+l^−) and Υ_D → 3V → 3(l+l−) (l = e, µ, π). The absence of such final states in the existing searches performed at BABAR and Belle sets new constraints on the parameter space of the model. We also show that a search for multiple bremsstrahlung of dark force mediators, e^+e^− → χχ¯ + nV , resulting in missing energy and multiple leptons, will further improve the sensitivity to self-interacting dark matter

Dark Sectors 2016 Workshop: Community Report

This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years