119499528
Charged Higgs boson pairs at the CERN LHC
We compute the cross section for pair production of charged Higgs bosons at the LHC and compare the three production mechanisms. The bottom-parton scattering process is computed to next-to-leading order (NLO), and the validity of the bottom-parton approach is established in detail. The light-flavor Drell-Yan cross section is evaluated at NLO as well. The gluon-fusion process through a one-loop amplitude is then compared with these two results. We show how a complete sample of events could look, in terms of total cross sections and distributions of the heavy final states.
15784150
Multi-photon signatures at the Fermilab Tevatron
Fermiophobic Higgs bosons (hf) exhibiting large branching ratios for decay to two photons can arise in models with two or more scalar doublets and/or triplets. In such models the conventional production mechanisms at hadron colliders, which rely on the hfVV coupling (V=W,Z), may be rendered ineffective due to severe mixing angle suppression. In this scenario, double hf production may proceed via the complementary mechanism qq’→H±hf with subsequent decay H±→hfW*, leading to events with up to four photons. We perform a simulation of the detection prospects of hf in the multi-photon (>3) channel at the Fermilab Tevatron and show that a sizeable region of the (mH±,mhf) parameter space can be probed during Run II.
119632193
Unravelling the sbottom spin at the CERN LHC
Establishing that a signal of new physics is undoubtedly supersymmetric requires not only the discovery of the supersymmetric partners but also probing their spins and couplings. We show that the sbottom spin can be probed at the CERN Large Hadron Collider using only angular correlations in the reaction pp{yields}b-tildeb-tilde*{yields}bbpe{sub T}, which allow us to distinguish a universal extra dimensional interpretation with a fermionic heavy bottom quark from supersymmetry with a bosonic bottom squark. We demonstrate that this channel provides a clear indication of the sbottom spin provided the sbottom production rate and branching ratio into b{chi}-tilde{sub 1}{sup 0} are sufficiently large to have a clear signal above standard model backgrounds.
117282788
Effective field theory approach to the Galactic Center gamma-ray excess
We explore the possibility of explaining a gamma-ray excess in the Galactic center, originally pointed out by Hooper, collaborators, and other groups, in an effective field theory framework. We assume that dark matter annihilation is mediated by particles heavy enough to be integrated out and that such particles couple to all quark families. We calculate the effective coupling required to explain the annihilation signal in the Galactic center and compare with bounds from direct detection, collider searches, and the requirement that the dark matter particles make up the appropriate fraction of the universal energy budget. We find that only a very small set of operators can explain the gamma-ray excess while being consistent with other constraints. Specifically, for scalar dark matter, the viable options are one scalar-type coupling to quarks and one interaction with gluons, while for fermionic (Dirac) dark matter, the viable options are two scalar-type dimension-7 operators or a dimension-6 vector-type operator. In all cases, future searches with the Large Hadron Collider should probe the relevant operators' effective energy scale, while all viable interactions should escape direct detection experiments.
118401678
Searching for Elko dark matter spinors at the CERN LHC
The aim of this paper is to explore the possibility of discovering a fermionic field with mass dimension one, the Elko field, in the Large Hadron Collider. Due to its mass dimension, an Elko can only interact either with Standard Model spinors and gauge fields at one-loop order or at tree level through a quartic interaction with the Higgs field. In this Higgs portal scenario, the Elko is a viable candidate to a dark matter constituent which has been shown to be compatible with relic abundance measurements from WMAP and direct dark matter searches. We propose a search strategy for this dark matter candidate in the channel at the LHC. We show the LHC potential to discover the Elko considering a triple Higgs–Elkos coupling as small as ~0.5 after 1 ab-1 of integrated luminosity. Some phenomenological consequences of this new particle and its collider signatures are also discussed.
118412313
A model with chiral quarks of electric charges −4/3 and 5/3
A bstractWe present a new model based on the SU(3)⨂SU(2)⨂U(1) symmetry, in which there is a new consistent set of chiral fermion fields that renders the model free from anomalies. The new fermions do not share the usual family structure of the Standard Model and some of them have exotic electric charges, as the quarks X and Y with electric charge 5/3 and −4/3, respectively. Interestingly, the model contains a new heavy neutral lepton which may be a dark matter candidate. Two Higgs doublets are present in our construction, so that two CP even scalars are present in the model particle spectrum. One of them is similar to the Standard Model Higgs boson, while the other one couples mainly with the new exotic fermions. We performed a discovery analysis showing that the 8 TeV LHC can find the Y quark from single and pair production with masses from 300 GeV up to ~ 750 GeV. We also show that the new spectrum does not contribute significantly to the oblique EW parameters, and that dangerous flavor changing neutral currents are suppressed. Characteristic signatures from the other new fermions in the model are also commented.
118422811
Measuring asymmetries in flavor asymmetric machines
The LHC offers a unique opportunity to investigate an ample spectra of phenomenous ranging from the Electro-Weak (EW) to the QCD sector of the Standard Model (SM). Among the quantities which can be measured in the LHC experiments are the CP and production asymmetries for several particles in a wide variety of decay modes. In this work we discuss about the interplay between production and CP asymmetries for particles produced in proton-proton interactions and the effects of one on the measurement of the other. This kind of effects are not present in flavor symmetric machines like the Tevatron or $e^+-e^-$ colliders.
197503274
First observations of the rare decays $B^+\!\rightarrow K^+\pi^+\pi^-\mu^+\mu^-$ and $B^+\!\rightarrow\phi K^+\mu^+\mu^-$
First observations of the rare decays $B^+\rightarrow K^+\pi^+\pi^-\mu^+\mu^-$ and $B^+\rightarrow \phi K^+\mu^+\mu^-$ are presented using data corresponding to an integrated luminosity of $3.0\,\mbox{fb}^{-1}$, collected by the LHCb experiment at centre-of-mass energies of $7$ and $8\mathrm{\,TeV}$. The branching fractions of the decays are \begin{eqnarray*} \mathcal{B}(B^+\rightarrow K^+\pi^+\pi^-\mu^+\mu^-) &=& (4.36\,^{+0.29}_{-0.27}\,\mathrm{(stat)}\pm 0.21\,\mathrm{(syst)}\pm0.18\,\mathrm{(norm)})\times10^{-7},\\ \mathcal{B}(B^+\rightarrow\phi K^+\mu^+\mu^-) &=& (0.82 \,^{+0.19}_{-0.17}\,\mathrm{(stat)}\,^{+0.10}_{-0.04}\,\mathrm{(syst)}\pm0.27\,\mathrm{(norm)}) \times10^{-7},\end{eqnarray*} where the uncertainties are statistical, systematic, and due to the uncertainty on the branching fractions of the normalisation modes. A measurement of the differential branching fraction in bins of the invariant mass squared of the dimuon system is also presented for the decay $B^+\rightarrow K^+\pi^+\pi^-\mu^{+}\mu^{-}$.
126244363
Heavy flavor physics in LHCb
199685274
Observation of overlapping spin-1 and spin-3 $\overline{D}^0 K^-$ resonances at mass $2.86 {\rm GeV}/c^2$