Phys. Rev. D 99, 035021 (2019) The $t\bar t$ plus missing energy channel is one of the most efficient to
detect third-generation leptoquarks (LQs). It offers an important test to
models which explain ...flavor anomalies in $B$ meson decays. We outline a search
strategy in the channel, relying on tagging the tops and on observables
constructed out of the tops, and we assess the reach on LQs of the future
high-luminosity LHC program. We find that with 3 ab$^{-1}$ a vector (scalar) LQ
decaying 50% (100%) to top and neutrino can be excluded up to masses of 1.96
TeV (1.54 TeV). We also indicate several observables that, in case of a future
discovery in the channel, can be used to distinguish a scalar LQ from a vector
LQ. The implications of our findings to models addressing the recent flavor
anomalies are finally discussed.
We discuss the interaction cross section $\bar\nu_e-p$ due to charged
currents, of major importance for neutrino detection. We present the history of
its understanding and highlight the aspects ...necessary for its precise
evaluation. We examine the three most recent determinations and, on the basis
of the most recent one, tabulate its updated values and assess its uncertainty.
Many compelling theories to address the Higgs hierarchy problem predict strong interactions between the top and a sector of New Physics. In minimal composite Higgs models (CHM), the top interactions ...with a BSM strongly-interacting sector give the leading contribution to trigger the EWSB and generate a light mass for the pseudo-NG Higgs. This implies that new composite states (vector-like top-partners, composite vector resonances, new composite scalars) dominantly interact with third-generation quarks and, when produced at colliders, generate top quarks in the final state. I will indicate interesting signatures involving top quarks for CHM discovery/test at the LHC and future colliders.
We discuss as accurately as possible the cross section of quasi-elastic scattering of electron (anti-)neutrinos on nucleons, also known as inverse beta decay in the case of antineutrinos. We focus on ...the moderate energy range from a few MeV up to hundreds of MeV, which includes neutrinos from reactors and supernovae. We assess the uncertainty on the cross section, which is relevant to experimental advances and increasingly large statistical samples. We estimate the effects of second-class currents, showing that they are small and negligible for current applications.
The $\tau$ lepton anomalous magnetic moment: $a_\tau = \frac{g_{\tau}-2}{2}$
was measured, so far, with a precision of only several percents despite its
highly sensitivity to physics beyond the ...Standard Model such as compositeness
or Supersymmetry. A new study is presented to improve the sensitivity of the
$a_\tau $ measurement with photon-photon interactions from ultra-peripheral
lead-lead collisions at LHC. The theoretical approach used in this work is
based on an effective Lagrangian and on a photon flux implemented in the
MadGraph5 Monte Carlo simulation. Using a multivariate analysis to discriminate
the signal from the background processes, a sensitivity to the anomalous
magnetic moment $\rm{a_{\tau}}$ = 0 $_{+0.011} ^{-0.019}$ is obtained at 95\%
CL with a dataset corresponding to an integrated luminosity of 2 nb$^{-1}$ of
lead-lead collisions and assuming a conservative 10\% systematic uncertainty.
The present results are compared with previous calculations and available
measurements.
A 3 sigma excess has been recently announced by ATLAS in events with Z-peaked dilepton pairs, jets, and large transverse missing energy. We interpret this finding in the context of composite Higgs / ...RS theories. We find that composite Higgs theories with custodial symmetry protection to the \(Zb\bar{b}\) coupling predict a significant contribution to \(ZZbb\) (and to \(hhbb\)) final states coming from heavy gluon decays to pairs of bottom-partner vector-like quarks. The heavy gluon to vector-like quarks signal is largely accepted by the ATLAS selection if one of the \(Z\) boson in the \(ZZbb\) final state decays leptonically and the other to neutrinos. For a bottom partner of \(\sim\)900 GeV, we find that the ATLAS excess can be reproduced by composite Higgs models, in an experimentally allowed parameter space, for heavy gluon masses roughly in a range 1.87 - 2.15 TeV and for heavy gluon couplings to light quarks within \(\sim(0.3-0.65) g_S\). We briefly discuss the implication of this result for future experimental tests.
The hypothesis that Dark Matter is one electroweak multiplet leads to predictive candidates with multi-TeV masses that can form electroweak bound states. Bound states with the same quantum numbers as ...electroweak vectors are found to be especially interesting, as they can be produced resonantly with large cross sections at lepton colliders. Such bound states exist e.g. if DM is an automatically stable fermionic weak 5-plet with mass \(M \approx\) 14 TeV such that the DM abundance is reproduced thermally. In this model, a muon collider could resolve three such bound states. Production rates are so large that details of DM spectroscopy can be probed with larger statistics: we compute the characteristic pattern of single and multiple \(\gamma\) lines.
The \(t\bar t\) plus missing energy channel is one of the most efficient to detect third-generation leptoquarks (LQs). It offers an important test to models which explain flavor anomalies in \(B\) ...meson decays. We outline a search strategy in the channel, relying on tagging the tops and on observables constructed out of the tops, and we assess the reach on LQs of the future high-luminosity LHC program. We find that with 3 ab\(^{-1}\) a vector (scalar) LQ decaying 50% (100%) to top and neutrino can be excluded up to masses of 1.96 TeV (1.54 TeV). We also indicate several observables that, in case of a future discovery in the channel, can be used to distinguish a scalar LQ from a vector LQ. The implications of our findings to models addressing the recent flavor anomalies are finally discussed.
A possible composite nature of the Higgs could be revealed at the early stage of the LHC, by analyzing the channels where the Higgs is produced from the decay of a heavy fermion. The Higgs production ...from a singly-produced heavy bottom, in particular, proves to be a promising channel. For a value \lambda=3 of the Higgs coupling to a heavy bottom, for example, we find that, considering a 125 GeV Higgs which decays into a pair of b-quarks, a discovery is possible at the 8 TeV LHC with 30 fb^{-1} if the heavy bottom is lighter than roughly 530 GeV (while an observation is possible for heavy bottom masses up to 650 GeV). Such a relatively light heavy bottom is realistic in composite Higgs models of the type considered and, up to now, experimentally allowed. At \sqrt{s}=14 TeV the LHC sensitivity on the channel increases significantly. With \lambda=3 a discovery can occur, with 100 fb^{-1}, for heavy bottom masses up to 1040 GeV. In the case the heavy bottom was as light as 500 GeV, the 14 TeV LHC would be sensitive to the measure of the \lambda\ coupling in basically the full range \lambda>1 predicted by the theory.
We re-consider recent measures of \(R_{K}\) and \(R_{K^*}\), now compatible with the Standard Model expectations, as well as the results for the process \(\text{BR}(B_s \rightarrow \mu^+ \mu^-)\) ...alongside earlier determinations of \(R_{D^{(\ast)}}\) and \(\text{BR}(B_c \rightarrow \tau \nu)\). We provide analytic constraints on the associated Wilson coefficients in both the \(b \to s\) and the \(b \to c\) sectors. These allow us to estimate the scale of potential New Physics for generic extensions of the Standard Model. We then use the results to constrain the leptoquark landscape.
