119180531
New results on the spectroscopy of XYZ states from LHC experiments
The main results from LHC experiments on XYZ charmonium-like candidates are summarized. 1 ar X iv :1 20 9. 01 18 v1 [ he pex ] 1 S ep 2 01 2
118556144
Jets Plus Same-Sign Dileptons Signatures from Fermionic Leptoquarks at the LHC
Within the 3-3-1 model framework, we consider the production and decay of fermionic leptoquarks into a striking experimental signature at the LHC: a narrow resonance at the b jet plus same-sign dileptons channel. The data already accumulated by the LHC collaborations may hide a large number of events associated to the production and decay of such exotic quarks, allowing one to investigate large portions of the parameters space of the model. The observation or not of such events would shed light on the construction of models presenting heavy exotic quarks. The hypothesis of the existence of new particles carrying two units of lepton number allows us to consider new physical phenomena which can be quite notable, if their masses are within the actual testable TeV energy scale. The decay of such exotic particles would lead to signatures that can not arise from any novel heavy states whose quantum numbers are the same as the ones in the standard model (SM). As a result, the signals would be almost free from SM backgrounds.
199685274
Observation of overlapping spin-1 and spin-3 $\overline{D}^0 K^-$ resonances at mass $2.86 {\rm GeV}/c^2$
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
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.
56111830
Is There a Hidden Principle in the Higgs Boson Decay to Photons
It is remarkable that the measured Higgs boson mass is so close to the value which maximizes the Higgs decay rate to photons as predicted by the Standard Model. In this letter we explore the consequences to assume that an ∼ 126 GeV Higgs boson mass is not accidental, but fixed by some fundamental principle that enforces it to maximize its decay rate into photons. We provide evidence that only a very narrow slice of the parameters space of the Standard Model, which contains their measured values, could lead to a maximal Higgs boson with that mass. If the principle actually holds, several Standard Model features get fixed, as the number of fermion families, quark colors, and the CP nature of the new boson, for example. We also ilustrate how such principle can place strong bounds on new physics scenarios as a Higgs dark portal model, for example.
118570640
Is the new resonance spin 0 or 2? Taking a step forward in the Higgs boson discovery
The observation of a new boson of mass $\sim 125\gev$ at the CERN LHC may finally have revealed the existence of a Higgs boson. Now we have the opportunity to scrutinize its properties, determining its quantum numbers and couplings to the standard model particles, in order to confirm or not its discovery. We show that by the end of the 8 TeV run, combining the entire data sets of ATLAS and CMS, it will be possible to discriminate between the following discovery alternatives: a scalar $J^P=0^+$ or a tensor $J^P=2^+$ particle with minimal couplings to photons, at a $5\sigma$ statistical confidence level at least, using only diphotons events. Our results are based on the calculation of a center-edge asymmetry measure of the reconstructed {\it sPlot} scattering polar angle of the diphotons. The results based on asymmetries are shown to be rather robust against systematic uncertainties with comparable discrimination power to a log likelihood ratio statistic.
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.
119279733
Production of Charged Higgs Bosons in a 3-3-1 Model at the CERN LHC
We perform a study of the charged Higgs production from an $SU(3{)}_{C}\ensuremath{\bigotimes}SU(3{)}_{L}\ensuremath{\bigotimes}U(1{)}_{X}$ model with right-handed neutrinos, postulating a custodial symmetry which reduces the number of free parameters in the scalar potential. We compute the cross sections for charged scalars for typical and new production modes. One of the new $SU(3{)}_{L}$ neutral gauge bosons, ${Z}^{\ensuremath{'}}$, affects some production cross sections distinguishing the model from other standard model extensions like, for example, the minimal supersymmetric standard model and general two-Higgs doublets models. The interplay between the Higgs sector of the model and that ${Z}^{\ensuremath{'}}$ gauge boson enhances substantially all the production rates of the lightest charged Higgs boson, ${H}_{1}^{\ifmmode\pm\else\textpm\fi{}}$, at hadron colliders compared to the MSSM. We found that a large portion of the parameters space can be probed at the LHC running at 14 TeV center-of-mass energy in the associated $pp\ensuremath{\rightarrow}{W}^{\ifmmode\pm\else\textpm\fi{}}{H}_{1}^{\ensuremath{\mp}}+X$ production channel in the low luminosity run stage of the experiment.