Phys. Rev. Lett. 123, 081802 (2019) A time-dependent analysis of the $B_s^0 \to \phi\gamma$ decay rate is
performed to determine the $CP$-violating observables $S_{\phi\gamma}$ and
$C_{\phi\gamma}$, ...and the mixing-induced observable
$\mathcal{A}^{\Delta}_{\phi\gamma}$. The measurement is based on a sample of
$pp$ collision data recorded with the LHCb detector, corresponding to an
integrated luminosity of 3 fb$^{-1}$ at center-of-mass energies of 7 and 8 TeV.
The measured values are \begin{align*} S_{\phi\gamma} &= 0.43 \pm 0.30 \pm
0.11, \\ C_{\phi\gamma} &= 0.11 \pm 0.29 \pm 0.11, \\
\mathcal{A}^{\Delta}_{\phi\gamma} &= -0.67 \, ^{+0.37}_{-0.41} \pm 0.17,
\end{align*} where the first uncertainty is statistical and the second
systematic. This is the first measurement of the observables $S$ and $C$ in
radiative $B_s^0$ decays. The results are consistent with the Standard Model
predictions.
Phys. Rev. Lett. 122, 222001 (2019) A narrow pentaquark state, $P_c(4312)^+$, decaying to $J/\psi p$ is
discovered with a statistical significance of $7.3\sigma$ in a data sample of
${\Lambda_b^0\to ...J/\psi p K^-}$ decays which is an order of magnitude larger
than that previously analyzed by the LHCb collaboration. The $P_c(4450)^+$
pentaquark structure formerly reported by LHCb is confirmed and observed to
consist of two narrow overlapping peaks, $P_c(4440)^+$ and $P_c(4457)^+$, where
the statistical significance of this two-peak interpretation is $5.4\sigma$.
Proximity of the $\Sigma_c^+\bar{D}^{0}$ and $\Sigma_c^+\bar{D}^{*0}$
thresholds to the observed narrow peaks suggests that they play an important
role in the dynamics of these states.
ALP-mediated decays and other as-yet unobserved \(B\) decays to di-photon final states are a challenge to select in hadron collider environments due to the large backgrounds that come directly from ...the \(pp\) collision. We present the strategy implemented by the LHCb experiment in 2018 to efficiently select such photon pairs. A fast neural network topology, implemented in the LHCb real-time selection framework achieves high efficiency across a mass range of \(4-20\) GeV\(/c^{2}\). We discuss implications and future prospects for the LHCb experiment.
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.
Long-lived particles (LLPs) are highly motivated signals of physics Beyond the Standard Model (BSM) with great discovery potential and unique experimental challenges. The LLP search programme made ...great advances during Run 2 of the Large Hadron Collider (LHC), but many important regions of signal space remain unexplored. Dedicated triggers are crucial to improve the potential of LLP searches, and their development and expansion is necessary for the full exploitation of the new data. The public discussion of triggers has therefore been a relevant theme in the recent LLP literature, in the meetings of the LLP@LHC Community workshop and in the respective experiments. This paper documents the ideas collected during talks and discussions at these Workshops, benefiting as well from the ideas under development by the trigger community within the experimental collaborations. We summarise the theoretical motivations of various LLP scenarios leading to highly elusive signals, reviewing concrete ideas for triggers that could greatly extend the reach of the LHC experiments. We thus expect this document to encourage further thinking for both the phenomenological and experimental communities, as a stepping stone to further develop the LLP@LHC physics programme.
