We consider a class of minimal extensions of the Standard Model with an extra massive neutral gauge boson Z'. They include both family-universal models, where the extra U(1) is associated with (B-L), and non-universal models where the Z' is coupled to a non-trivial linear combination of B and the lepton flavours. After giving an estimate of the range of parameters compatible with a Grand Unified Theory, we present the current experimental bounds, discussing the interplay between electroweak precision tests and direct searches at the Tevatron. Finally, we assess the discovery potential of the early LHC.
The CDF PYTHIA 6.2 Tune DW predictions of the LHC underlying event (UE) data at 900 GeV and 7 TeV are examined in detail. The behavior of the UE at the LHC is roughly what we expected. The new LHC PYTHIA 6.4 Tune Z1 does an even better job describing the UE data at 900 GeV and 7 TeV. However, the modeling of "min-bias" at the LHC (i.e. the overall inelastic cross section) is a very different story. No model describes all the features of "min-bias" collisions at 900 GeV and 7 TeV.
LHC already probed and excluded half of the parameter space of the Constrained Minimal Supersymmetric Standard Model allowed by previous experiments. Only about 0.3% of the CMSSM parameter space survives. This fraction rises to about 0.9% if the bound on the Higgs mass can be circumvented.
We discuss the implementation of the "minimal" type III seesaw model, i.e. with one fermionic triplet, in FeynRules/MadGraph. This is the first step in order to realize a real study of LHC data recorded in the LHC detectors. With this goal in mind, we comment on the possibility of discovering this kind of new physics at the LHC running at 7 TeV with a luminosity of few fb^-1.
We use the recent measurements of top quark decay asymmetries in ATLAS and the t-channel single top cross section in CMS to set the first combined LHC limits on the Wtb vertex. This combination allows to obtain much better limits than the separate measurements. The resulting constraints are comparable, although still weaker, than the ones obtained using Tevatron data with much more statistics.
In this review I sketch the basic criteria and boundary conditions which have guided the design of the LHC detectors. The discussion will concentrate on the so-called general-purpose experiments, ATLAS and CMS. After an overview of the detector's characteristics and performance, I will elaborate on the expected measurements of hard processes, with emphasis on jet and vector boson production, i.e., tests of Quantum Chromodynamics (QCD) and Electroweak Physics.
The non-minimal Higgs-gravity coupling, $ξH^\dagger H R$, can play an interesting role in particle physics. We utilize the available LHC Run-2 data to obtain the bound on the coupling $ξ$ and discuss the prospects of constraining it at CEPC, FCC-ee and ILC. Also, we investigate its implication on the naturalness.
We explore the potential for discovery of an exotic color sextet scalar in same-sign top quark pair production in early running at the LHC. We present the first phenomenological analysis at colliders of color sextet scalars with full top quark spin correlations included. We demonstrate that one can measure the scalar mass, the top quark polarization, and confirm the scalar resonance with 1 inverse fb of integrated luminosity. The top quark polarization can distinguish gauge triplet and singlet scalars.
We propose and investigate a novel, minimal, and experimentally testable framework for baryogenesis, dubbed dexiogenesis, using baryon number violating effective interactions of right-handed Majorana neutrinos responsible for the seesaw mechanism. The distinct LHC signature of our framework is same-sign top quark final states, possibly originating from displaced vertices. The region of parameters relevant for LHC phenomenology can also yield concomitant signals in nucleon decay experiments. We provide a simple ultraviolet origin for our effective operators, by adding a color-triplet scalar, wh…
We present a detailed study of the anomalous top quark production with subsequent decay at the LHC induced by model-independent flavor-changing neutral-current couplings, incorporating the complete next-to-leading order QCD effects. Our results show that, taking into account the current limits from the Tevatron, the LHC with $\sqrt{s}=7$ TeV may discover the anomalous coupling at 5$σ$ level for a very low integrated luminosity of 61 pb$^{-1}$. The discovery potentials for the anomalous couplings at the LHC are examined in detail. We also discuss the possibility of using the charge ratio to dis…
LHCb is a dedicated detector for b and c physics at the LHC. I will present a concise review of the detector design and expected performance together with some first results on the commissioning of the different sub-systems based on cosmic data and particle beams delivered by the LHC during the summer of 2008. The experiment is ready to exploit first data expected from the LHC. An integrated luminosity of ~0.3fb-1, which should be collected during the first year of physics running, will already allow LHCb to perform a number of very significant mesurements with the potential of revealing New P…
We investigate the potential of the early LHC to discover the signal of monotops, which can be decay products of some resonances in models such as R-parity violating SUSY or SU(5), etc. We show how to constrain the parameter space of the models by the present data of $Z$ boson hadronic decay branching ratio, $K^0-\bar{K^0}$ mixing and dijet productions at the LHC. Then, we study the various cuts imposed on the events, reconstructed from the hadronic final states, to suppress backgrounds and increase the significance in detail. And we find that in the hadronic mode the information from the miss…
Low-scale gauge-mediated supersymmetry(SUSY)-breaking (GMSB) models with gravitino mass m_{3/2}<16 eV are attractive, since there are no flavor and cosmological problems. In this paper, we thoroughly study the collider signal in the case that the next-to-lightest SUSY particle is the bino or slepton and investigate the discovery potential of the LHC. Our result is applicable to a wider class of GMSB models other than the minimal GMSB models and we pay particular attention to realistic experimental setups. We also apply our analysis to the minimal GMSB models with a metastable SUSY-breaking vac…
W' gauge bosons are good candidates for early LHC discovery. We define two reference models, one containing a W'_R and one containing a W'_L, which may serve as ``simplified models'' for presenting experimental results of W' searches at the LHC. We present the Tevatron bounds on each model and compute the constraints from precision electroweak observables. We find that indirect low-energy constraints on the W'_L are quite strong. However, for a W'_R coupling to right-handed fermions there exists a sizeable region in parameter space beyond the bounds from the Tevatron and low-energy precision m…
Among various supersymmetric (SUSY) standard models, the gravity mediation model with a neutralino LSP and the gauge mediation model with a very light gravitino are attractive from the cosmological view point. These models have different scales of SUSY breaking and their underlying physics in high energy is quite different. However, if the sparticles' decay into the gravitino is prompt in the latter case, their collider signatures can be similar: multiple jets and missing transverse momentum. In this paper, we study the discrimination between these models in minimal cases at the LHC based on t…
In the very early stages of LHC running, uncertainties in detector performance will lead to large ambiguities in jet, electron and photon energy measurements, along with inferred missing transverse energy. However, muon detection should be quite straightforward, with the added benefit that muons can be reliably detected down to transverse energies of order 5 GeV. Supersymmetry discovery through multimuon channels has been extensively explored in the literature, but always relying on hard ET^miss cuts. Here, we quantify signal and background rates for same-sign (SS) dimuon and multimuon product…
If the LHC experiments discover new particles that couple to the Standard Model fermions, then measurements by ATLAS and CMS can contribute to our understanding of the flavor puzzles. We demonstrate this statement by investigating a scenario where extra SU(2)-singlet down-type quarks are within the LHC reach. By measuring masses, production cross sections and relative decay rates, minimal flavor violation (MFV) can in principle be excluded. Conversely, these measurements can probe the way in which MFV applies to the new degrees of freedom. Many of our conclusions are valid in a much more gener…
We study, within an effective approach, the phenomenology of a charged W' vector which transforms as an isosinglet under the Standard Model gauge group. We discuss bounds from present data, finding that these are quite weak for suitable choices of the right-handed quark mixing matrix. Then we study the resonant production at the early LHC of such a weakly constrained W'. We start discussing the reach in the dijet final state, which is one of the channels where the first W' signal would most likely appear, and then we analyse prospects for the more challenging discovery of W' decays into Wγ and…
We carry out an analysis of the potential of the Large Hadron Collider (LHC) to discover supersymmetry in runs at $\sqrt s=7$ TeV with an accumulated luminosity of (0.1--2) fb$^{-1}$ of data. The analysis is done both with minimal supergravity (mSUGRA) and supergravity (SUGRA) models with non-universal soft breaking. Benchmarks for early discovery with (0.1--2) fb$^{-1}$ of data are given. We provide an update of b-tagging efficiencies in PGS 4 appropriate for LHC analyses. A large number of signature channels are analyzed and it is shown that each of the models exhibited are discoverable at t…
We propose simple freeze-in models where the observed dark matter abundance is explained via the decay of an electrically charged and/or coloured parent particle into Feebly Interacting Massive Particles (FIMP). The parent particle is long-lived and yields a wide variety of LHC signatures depending on its lifetime and quantum numbers. We assess the current constraints and future high luminosity reach of these scenarios at the LHC from searches for heavy stable charged particles, disappearing tracks, displaced vertices and displaced leptons. We show that the LHC constitutes a powerful probe of …
The LHC era just began. The first discovery at the LHC experiment would be arguably a new resonance pole at TeV scale, if it exists. While the discovery of the Z' would be exciting by itself, it may also suggest what other new physics signals should be looked for while the LHC experiment is still at its early stage. We argue that the four lepton resonance at the Z' pole is a well-motivated and promising signal especially in supersymmetry framework, which can serve as a supersymmetry search scheme even in the early stage of the LHC experiment.
We study the LHC signatures of new gauge bosons in the gauge-invariant minimal Higgsless model. It predicts an extra pair of W_1 and Z_1 bosons which can be as light as ~400GeV and play a key role in the delay of unitarity violation. We analyze the W_1 signals in pp --> W_0Z_0Z_0 --> jj4\ell and pp --> jj W_0Z_0 --> jj3\ellνprocesses at the LHC, including the complete electroweak and QCD backgrounds. We reveal the complementarity between these two channels for discovering the W_1 boson, and demonstrate the LHC discovery potential over the full range of allowed W_1 mass.
We show that the early LHC measurements can provide crucial checks of the different components of the formalism used to predict the cross sections of central exclusive processes.
We study the phenomenology of the heavy charged gauge boson and obtain the lower bounds on its mass with the early LHC data at 7 TeV center-of-mass energy in the nonuniversal gauge interaction model, in which the electroweak SU(2) gauge group depends upon the fermion family. We found that the direct bound on the mass of the $W'$ boson is compatible to the indirect bound with only the early data of the LHC.
Gauge mediated supersymmetry breaking (GMSB) is a theoretically well-motivated framework with rich and varied collider phenomenology. In this paper, we study the Tevatron limits and LHC discovery potential for a wide class of GMSB scenarios in which the next-to-lightest superpartner (NLSP) is a promptly-decaying neutralino. These scenarios give rise to signatures involving hard photons, $W$'s, $Z$'s, jets and/or higgses, plus missing energy. In order to characterize these signatures, we define a small number of minimal spectra, in the context of General Gauge Mediation, which are parameterized…
We demonstrate that there are regions of parameter space in the next-to-minimal (i.e. two-Higgs-doublet, one-Higgs-singlet superfield) supersymmetric extension of the SM for which none of the Higgs bosons are observable either at LEP2 with $\sqrt{s}=192 GeV$ and an integrated luminosity of $L=1000 inverse pb$ or at the LHC with $L=600 inverse fb$.
We reexamine the models with gauge mediation in view of the minimality. As a result, we arrive at a very simple model of direct gauge mediation which does not suffer from the flavor problems nor the CP problems. We show that the parameter space which is consistent with the Higgs boson mass at around 126 GeV can be tested through the stable stau searches at the 14TeV run of the LHC. The gravitino is a viable candidate for a dark matter. We also give a short discussion on a possible connection of our model to the recently discovered X-ray line signal at 3.5 keV in the XMM Newton X-ray observator…
We consider `minimal' Z' models, whose phenomenology is controlled by only three parameters beyond the Standard Model ones: the Z' mass and two effective coupling constants. They encompass many popular models motivated by grand unification, as well as many arising in other theoretical contexts. This parameterization takes also into account both mass and kinetic mixing effects, which we show to be sizable in some cases. After discussing the interplay between the bounds from electroweak precision tests and recent direct searches at the Tevatron, we extend our analysis to estimate the early LHC d…
We explore the opportunity to look for large extra dimensions in the early stages of the LHC running. The high-E$_T$ dijet production is analyzed via a novel kinematic variable when the machine center-of-mass energy varies from 7 TeV through 10 TeV to 14 TeV and the accumulated data range from 0.5 to 8 fb$^{-1}$. The estimations of the reach in the effective scale $M_S$ for different numbers of large extra dimensions are presented.
In our recent paper [1], we explored a prospect of discovering the heavy Majorana right-handed neutrinos (RHNs) at the future LHC in the context of the minimal non-exotic U(1) extended Standard Model (SM), where a pair of RHNs are created via decay of resonantly produced massive U(1) gauge boson ($Z^{\prime}$). We pointed out that this model can yield a significant enhancement of the branching ratio of the $Z^\prime$ boson to a pair of RHNs, which is crucial for discovering the RHNs under the very severe LHC Run-2 constraint from the search for the $Z^\prime$ boson with dilepton final states. …
We investigate signatures of the minimal supersymmetric inverse seesaw model at the large hadron collider (LHC) with three isolated leptons and large missing energy (3\ell + \mET or 2\ell + 1τ+ \mET, with \ell=e,μ) in the final state. This signal has its origin in the decay of chargino-neutralino (\chpm1\ntrl2) pair, produced in pp collisions. The two body decays of the lighter chargino into a charged lepton and a singlet sneutrino has a characteristic decay pattern which is correlated with the observed large atmospheric neutrino mixing angle. This correlation is potentially observable at the …
If the effective cosmological constant $Λ$ of the present universe is due to physical processes in the early universe operating at temperatures just above the electroweak energy scale, it is possible that new particles with multi-$\text{TeV}$ masses exist. These ultraheavy particles may (or may not) show up at the Large Hadron Collider (LHC) or a next-generation proton-proton collider. If they do, they may provide new insights into the early universe and fundamental physics.
I discuss simple extensions of the Standard Model scalar sector that can help solve the origin of matter problem and that can be probed in their cosmologically relevant parameter space at the LHC.
We update our analysis of the Higgs sector masses in Minimal Supersymmetry and in the Two-Higgs Doublet Model to the final ATLAS and CMS data from the 2011-2012 LHC run.
We investigate the simplest gauge theory for spontaneous R-parity breaking and its testability at the LHC. This theory based on a local B-L gauge symmetry can be considered as the simplest framework for understanding the origin of the R-parity violating interactions, giving rise to potential lepton number violating signals and suppressed baryon number violating operators. The full spectrum of the theory and the constraints coming from neutrino masses are analyzed in great detail. We discuss the proton decay issue and the possible dark matter candidates. In order to assess the testability of th…
We review possible properties of Higgs bosons in the NMSSM, which allow to discriminate this model from the MSSM: masses of mostly Standard-Model-like Higgs bosons at or above 140 GeV, or enhanced branching fractions into two photons, or Higgs-to-Higgs decays. In the case of a Standard-Model-like Higgs boson above 140 GeV, it is necessarily accompagnied by a lighter state with a large gauge singlet component. Examples for such scenarios are presented. Available studies on Higgs-to-Higgs decays are discussed according to the various Higgs production modes, light Higgs masses and decay channels.
In this paper, we constrain CP violation in the Higgs sector using the measured signal strengths in the various Higgs search channels. To this end, we introduce a general parameterization for a resonance which is an admixture of a CP-even Higgs-like state and a CP-odd scalar. By performing a fit to the available data from the Tevatron and LHC experiments one obtains constraints on the mixing angle and the couplings of the resonance to Standard Model fields. Depending on the couplings, sizable mixing angles are still compatible with the data, but small mixing is in general preferred by the fit.…
We consider non-universal 'minimal' Z' models, whose additional U(1) charge is a non-anomalous linear combination of the weak hypercharge Y, the baryon number B and the partial lepton numbers (L_e, L_mu, L_tau), with no exotic fermions beyond three standard families with right-handed neutrinos. We show that the observed pattern of neutrino masses and mixing can be fully reproduced by a gauge-invariant renormalizable Lagrangian, and flavor-changing neutral currents in the charged lepton sector are suppressed by a GIM mechanism. We then discuss the phenomenology of some benchmark models. The ele…
With the start-up of the LHC, we can hope to find evidences for new physics beyond the Standard Model, and particle candidates for dark matter. Determining the parameters of the full underlying theory will be a long process requiring the combination of LHC and ILC data, flavor physics constraints, and cosmological observations. However, the Very Early Universe properties, from which the relic particles originate, are poorly known, and the relic density calculation can be easily falsified by hidden processes. We consider supersymmetry and show that determining the underlying particle physics pa…
We examine the ability of LHC experiments to observe jets from squark pair production at the center-of-mass energy E$_{CM}$=10 TeV and 1 fb$^{-1}$ of integrated luminosity. We point out the crucial influence of initial- and final-state radiation on the signal/background discriminating ability of different kinematic variables. The reliable measurements of missing transverse energy and stransverse mass would play a key role in picking out the signal against the background.
Many techniques exist to reconstruct New Physics masses from LHC data, though these tend to either require high luminosity O(100) fb^-1, or an accurate measurement of missing transverse energy (MET) which may not be available in the early running of the LHC. Since in popular models such as SUSY a fairly sharp, triangular dilepton invariant mass spectrum can emerge already at low luminosity O(1) fb^-1, a Decay Kinematics (DK) technique can be used on events near the dilepton mass endpoint to estimate squark, slepton, and neutralino masses without relying on MET. With the first 2 fb^-1 of 7 TeV …
Resonance searches generally focus on narrow states that would produce a sharp peak rising over background. Early LHC running will, however, be sensitive primarily to broad resonances. In this paper we demonstrate that statistical methods should suffice to find broad resonances and distinguish them from both background and contact interactions over a large range of previously unexplored parameter space. We furthermore introduce an angular measure we call ellipticity, which measures how forward (or backward) the muon is in eta, and allows for discrimination between models with different parity …
We investigate what new physics signatures the LHC can discover in the 2009-2010 run, beyond the expected sensitivity of the Tevatron data by 2010. We construct "supermodels", for which the LHC sensitivity even with only 10 inverse picobarn is greater than that of the Tevatron with 10 inverse femtobarn. The simplest supermodels involve s-channel resonances in the quark-antiquark and especially in the quark-quark channels. We concentrate on easily visible final states with small standard model backgrounds, and find that there are simple searches, besides those for Z' states, which could discove…
We discuss the possibility to observe new resonances at the early LHC using a phenomenological approach. We show predictions for the production of a scalar in the gg-channel and an heavy quark in the qg-channel and we compare them with the recent results of the ATLAS and CMS experiments in the di-jet channel, setting upper limits on the relevant couplings. We finally discuss the importance of the final states containing at least one photon making sensitivity predictions for the corresponding couplings.
Models of minimal lepton flavor violation where the seesaw scale is higher than the relevant flavor scale predict that all lepton flavor violation is proportional to the charged lepton Yukawa matrix. If extra vector-like leptons are within the reach of the LHC, it will be possible to test the resulting predictions in ATLAS/CMS.
We investigate the discovery potential of the LHC experiments for R-parity violating supersymmetric models with a stau as the lightest supersymmetric particle (LSP) in the framework of minimal supergravity. We classify the final states according to their phenomenology for different R-parity violating decays of the LSP. We then develop event selection cuts for a specific benchmark scenario with promising signatures for the first beyond the Standard Model discoveries at the LHC. For the first time in this model, we perform a detailed signal over background analysis. We use fast detector simulati…
We investigate new physics that could be discovered with very little LHC data, beyond the expected sensitivity of the Tevatron. We construct "supermodels", for which the LHC sensitivity with 10 pb-1 luminosity is already greater than that of the Tevatron with 10 fb-1. The simplest supermodels involve s-channel resonances in the quark-antiquark and especially in the quark-quark channels. In the latter case, the LHC sensitivity with 0.1 pb-1 can already be greater than that of the Tevatron with 10 fb-1. We concentrate on easily visible final states with small standard model backgrounds, and find…
We study how the recent ATLAS and CMS Higgs mass bounds affect the renormalization group running of the physical parameters in universal extra dimensions. Using the running of the Higgs self-coupling constant, we derive bounds on the cutoff scale of the extra-dimensional theory itself. We show that the running of physical parameters, such as the fermion masses and the CKM mixing matrix, is significantly restricted by these bounds. In particular, we find that the running of the gauge couplings cannot be sufficient to allow gauge unification at the cutoff scale.
We have examined the dijet production at the LHC as a hint to discovery of string Regge excitations of Standard Model particles. If the fundamental string mass scale is in the TeV range, the influence of string effects on the $pp$ interaction can arise as new resonances in the dijet invariant mass distribution. Near the first resonant pole we investigate the impact of the subprocesses with quark-gluon and four-gluon separately. We show that the LHC is able to probe the string mass scale $\sim$5 TeV with only 2 pb$^{-1}$ of integrated luminosity at $E_{CM}=14$ TeV.
We investigate the collider phenomenology of gluino-bino co-annihilation scenario both at the Tevatron and 7 TeV LHC. This scenario can be realized, for example, in a class of realistic supersymmetric models with non-universal gaugino masses and t-b-τYukawa unification. The NLSP gluino and LSP bino should be nearly degenerate in mass, so that the typical gluino search channels involving leptons or hard jets are not available. Consequently, the gluino can be lighter than various bounds on its mass from direct searches. We propose a new search for NLSP gluino involving multi-b final states, aris…
We study the production of the heavy W' and Z' bosons in the three site higgsless model at the LHC. We focus on the s-channel production mode to estimate the prospects for measuring their suppressed couplings to standard model fermions.
Most SUSY searches at the LHC are optimised for the MSSM, where gauginos are Majorana particles. By introducing Dirac gauginos, we obtain an enriched phenomenology, from which considerable differences in the LHC signatures and limits are expected as compared to the MSSM. Concretely, in the minimal Dirac gaugino model (MDGSSM) we have six neutralino and three chargino states. Moreover, production cross sections are enhanced for gluinos, while for squarks they are suppressed. In this contribution, we explore the consequences of the current LHC limits on gluinos and squarks in this model.
We revisit discovery prospects for a long-lived sterile neutrino $N$ at the Large Hadron Collider (LHC) in the context of left-right symmetric theories. We focus on a displaced vertex search strategy sensitive to $\mathcal{O}$(GeV) neutrino masses produced via a right-handed $W_{R}$ boson. Both on-shell and off-shell Drell-Yan production of $W_{R}$ are considered. We estimate the reach as a function of $m_{N}$ and $m_{W_{R}}$. With $\sqrt{s}=13$ TeV and 300/fb of integrated luminosity, the LHC can probe neutrino masses as high as $\sim 30$ GeV and $m_{W_{R}}$ around 6 TeV. The reach goes up to…
The prospects for discovering neutral Higgs bosons in the minimal supersymmetric model (MSSM) and in the minimal supergravity model at the LHC are investigated. Two special discovery channels are discussed: (i) the decay mode of the MSSM CP-odd Higgs boson into photon pairs, and (ii) the decays of neutral Higgs bosons into muon pairs in the MSSM as well as in the minimal supergravity model.
We discuss the collider phenomenology of the model of Minimal Universal Extra Dimensions (MUED) at the Large hadron Collider (LHC). We derive analytical results for all relevant strong pair-production processes of two level 1 Kaluza-Klein partners and use them to validate and correct the existing MUED implementation in the fortran version of the PYTHIA event generator. We also develop a new implementation of the model in the C++ version of PYTHIA. We use our implementations in conjunction with the CHECKMATE package to derive the LHC bounds on MUED from a large number of published experimental …
In this paper we explore the possibility of a pseudoscalar resonance to account for the 750 GeV diphoton excess observed both at ATLAS and at CMS. We analyze the ingredients needed from the low energy perspective to obtain a sufficiently large diphoton rate to explain the signal while avoiding constraints from other channels. Additionally, we point out composite Higgs models in which one can naturally obtain a pseudoscalar at the 750 GeV mass scale and we estimate the pseudoscalar couplings to standard model particles that one would have in such models. A generic feature of models that can exp…
Adding a fermion to the standard model particle content which is a fiveplet under $SU(2)_L$ gives a dark matter candidate. The lightest state in the multiplet is neutral and automatically stable. The charged component of the multiplet is only slightly heavier and can travel a finite distance in the LHC detectors before decaying, leaving a charged track which disappears before the edge of the detector. We use the recent ATLAS and CMS searches to exclude a Majorana fiveplet with a mass up to 267 GeV. We estimate that with 3 ab$^{-1}$ of $\sqrt{s}=14$ TeV data this could be pushed to a mass 520 G…
We explore the opportunity to look for quark compositeness in the early stages of the LHC running by analyzing high-$E_T$ dijet production. The quark substructure that will manifest itself by affecting various kinematic distributions at the center-of-mass energy $E_{CM}$=10 TeV and in the integrated luminosity range from 0.5 to 10 fb$^{-1}$ is investigated. The estimation of the characteristic energy scale $Λ$, based on the novel, potentially powerful observable, is found to be sensitive to the sign of the interference between Standard Model and four-fermion contact interactions. We find the l…
We perform a study of the LHC discovery reach on a heavy gluon (G*) and heavy fermions (top and bottom excitations), coming from a new composite sector. We find that heavy fermion resonances have a great impact on the composite gluon phenomenology. If the composite gluon is heavier than composite fermions, as flavor observables seem to suggest, the search in the channel where G* decays into a heavy fermion plus its Standard Model partner is very promising, with the possibility for both the G* and heavy fermions to be discovered at the early stage of the LHC. The channel offers also the possibi…
Freeze-in mechanism provides robust dark matter production in the early universe. Due to its feeble interactions, freeze-in dark matter leaves signals at colliders which are often involved with long lived particle decays and consequent displaced vertices (DV). In this paper, we develop a method to read off mass spectrum of particles being involved in the DV events at the LHC. We demonstrate that our method neatly works under a limited statistics, detector resolution and smearing effects. The signature of DV at the LHC can come from either highly suppressed phase-space or a feeble coupling of p…
Dirac gauginos are a well-motivated extension of the MSSM, leading to interesting phenomenological consequences. At the LHC, gluino-pair production is enhanced while squark production is suppressed as compared to the MSSM, and the decay signatures are altered by a more complex chargino and neutralino spectrum. We investigate how this impacts current gluino and squark mass limits from Run~2 of the LHC. Concretely, we compare different assumptions about the electroweak-ino spectrum through four benchmark models paying particular attention to the effect of the trilinear $λ_S$ coupling, which indu…
