Single Productions of Colored Particles at the LHC: An Example with Scalar Leptoquarks

Current LHC searches for new colored particles generally focus on their pair production channels and assume any single production to be negligible. We argue that such an assumption may be unnecessary in some cases. Inclusion of model dependent single productions in pair production searches (or vice versa) can give us new information about model parameters or better exclusion limits. Considering the example of the recent CMS search for first generation scalar leptoquarks in the pair production channel, we illustrate how single productions can be systematically included in the signal estimations and demonstrate how it can affect the mass exclusion limits and give new bounds on leptoquark-lepton-quark couplings. We also estimate the effect of the pair production in the more recent CMS search for scalar leptoquarks in single production channels.Comment: 11 pages, 6 figures, 2 tables. References added. Comments added on LQ single production search by CMS. Journal versio

Probing Compositeness with the CMS eejjeejj & eejeej Data

Quark-lepton compositeness is a well-known beyond the Standard Model (SM) scenario with heavy exotic particles like leptoquarks (LQs) and leptogluons (LGs) etc. These particles can couple to leptons and jets simultaneously. In this letter, we use the recent CMS scalar LQ search data in the $eejj$ and $eej$ channels to probe this scenario. We recast the data in terms of a color octet partner of the SM electron (or a first generation spin-1/2 LG) that couples to an electron and a gluon via a dimension five operator suppressed by the quark-lepton compositeness scale ($\Lambda$). By combining different production processes of the color octet electron ($e_8$) at the LHC, we use the CMS 8TeV data to obtain a simultaneous bound on $\Lambda$ and the mass of the $e_8$ ($M_{e_8}$). We also study the reach of the 13 TeV LHC to discover the $e_8$ and interpret the required luminosity in terms of $M_{e_8}$ and $\Lambda$.Comment: 7 pages, 6 figures, 3 tables. Minor changes, typos fixed. Matches with the published versio

RS resonance in di-final state production at the LHC to NLO+PS accuracy

We study the di-final state processes ($\ell^+ \ell^-$, $\gamma \gamma$, $ZZ$, $W^+ W^-$) to NLO+PS accuracy, as a result of both the SM and RS Kaluza-Klein graviton excitations. Decay of the electroweak gauge boson final states to different leptonic states are included at the showering stage. A selection of the results has been presented with PDF and scale uncertainties for various distributions. Using the di-lepton and di-photon final states, we present the search sensitivity, for the $14$ TeV LHC at $50$ fb$^{-1}$ luminosity.Comment: 20 pages, 14 figure

Precise probing of the inert Higgs-doublet model at the LHC

The inert Higgs-doublet model provides a simple framework to accommodate a viable Higgs portal scalar dark matter candidate, together with other heavier scalars of mass 100 GeV or more. We study the effect of next-to-leading order (NLO) QCD corrections in this scenario in the context of the Large Hadron Collider. ${\cal{O}}(\alpha_s)$ corrections to the gluon-gluon-Higgs effective coupling have been taken into account in this study wherever appropriate. We find such corrections have a significant impact on various kinematic distributions and reduce scale uncertainties substantially. Fixed order NLO results are matched to the {\sc Pythia8} parton shower (PS) and the di-fatjet signal associated with the missing transverse momentum is analyzed, as this channel has the ability to explore its entire parameter space during the next phase of the LHC run. A closer look at the NLO+PS computation indicates a sizable NLO effect together with a subdued contribution from associated production of the heavy scalar compared to the pair production, thereby leading to a refined analysis strategy during the multivariate analysis of this signal.Comment: 22 pages, 11 figures, and 6 tables. This version matches the published versio

Neutral triple electroweak gauge boson production in the large extra-dimension model at the LHC

We study the prospects of probing large extra dimension model at the LHC through neutral triple gauge boson production processes. In theories with extra dimensions these processes result from the exchange of a tower of massive graviton modes between the SM particles. We consider \gamma\gamma\gamma, \gamma \gamma Z, \gamma Z Z and ZZZ production processes, and present our results for various kinematic distributions at the LHC for \sqrt{S}=14 TeV.Comment: 13 pages, 9 figures, version to appear in PR

Jet-veto resummation at N3^3LLp_\text{p}+NNLO in boson production processes

Vetoing energetic jet activity is a crucial tool for suppressing backgrounds and enabling new physics searches at the LHC, but the introduction of a veto scale can introduce large logarithms that may need to be resummed. We present an implementation of jet-veto resummation for color-singlet processes at the level of N$^3$LL$_\text{p}$ matched to fixed-order NNLO predictions. Our public code MCFM allows for predictions of a single boson, such as $Z/\gamma^*$, $W^{\pm}$ or $H$, or with a pair of vector bosons, such as $W^+W^-$, $W^{\pm} Z$ or $ZZ$. The implementation relies on recent calculations of the soft and beam functions in the presence of a jet veto over all rapidities, with jets defined using a sequential recombination algorithm with jet radius $R$. However one of the ingredients that is required to reach full N$^3$LL accuracy is only known approximately, hence N$^3$LL$_\text{p}$. We describe in detail our formalism and compare with previous public codes that operate at the level of NNLL. Our higher-order predictions improve significantly upon NNLL calculations by reducing theoretical uncertainties. We demonstrate this by comparing our predictions with ATLAS and CMS results.Comment: 58 pages, 19 Figures, published version with additional figures (Fig.13 and Fig.18(b)) assessing uncertainty caused by the unknown d_3^veto. Improvement of language on logarithmic order of initial gluon contributions and comparison with JetVHeto. Recalculation of resummed uncertainties, giving minor updates to figures throughout. Qualitative conclusions are unchange