We assess the performance of different jet-clustering algorithms, in the presence of different resolution parameters and reconstruction procedures, in resolving fully hadronic final states emerging from the chain decay of the discovered Higgs boson into pairs of new identical Higgs states, the latter in turn decaying into bottom-antibottom quark pairs. We show that, at the Large Hadron Collider (LHC), both the efficiency of selecting the multi-jet final state and the ability to reconstruct from it the masses of the Higgs bosons (potentially) present in an event sample depend strongly on the choice of acceptance cuts, jet-clustering algorithm as well as its settings. Hence, we indicate the optimal choice of the latter for the purpose of establishing such a benchmark Beyond the SM (BSM) signal.
The Gell-Mann$-$Okubo (GMO) mass relations following from $\text{SU}(3)$-flavor symmetry breaking in the strong sector have been proven to be of great success for describing hadron masses and classifying them into multiplets. Nowadays, it is widely believed that baryons being fermions have to obey GMO relations which are linear in the baryon masses, whilst mesons as bosons follow quadratic GMO relations. In this work, I challenge the distinction of GMO relations for baryons and mesons and conclude that both linear and quadratic GMO relations apply to both baryons and mesons in most instances (…
The production of heavy-flavored hadron at the hadronic colliders provides a challenging opportunity to test the validity of pQCD predictions. There are two mechanisms for the $B^{(*)}_s$ hadroproduction, i.e. the gluon-gluon fusion mechanism via the subprocess $g+g\rightarrow B^{(*)}_s+b+\bar{s}$ and the extrinsic heavy quark mechanism via the subprocesses $g+\bar{b}\to B^{(*)}_s +\bar{s}$ and $g+s\to B^{(*)}_s +b$, both of which shall have sizable contributions in proper kinematic region. Different from the fixed-flavor-number scheme (FFNS) previously adopted in the literature, we study the …
We revisit the case of a light neutralino LSP in the framework of the MSSM. We consider a model with eleven free parameters. We show that all scenarios where the annihilation of light neutralinos rely mainly on the exchange of a light pseudoscalar are excluded by direct detection searches and by Fermi measurements of the gamma-flux from dwarf spheroidal galaxies. On the other hand, we find scenarios with light sleptons that satisfy all collider and astroparticle physics constraints. In this case, the lower limit on the LSP mass is 12.6 GeV. We discuss how the parameter space of the model will …
Within the framework of QCD factorization (QCDF), we consider two different types of power correction effects in order to resolve the CP puzzles and rate deficit problems with penguin-dominated two-body decays of B mesons and color-suppressed tree-dominated $π^0π^0$ and $ρ^0π^0$ modes: penguin annihilation and soft corrections to the color-suppressed tree amplitude. We emphasize that the electroweak penguin solution to the $B\to Kπ$ CP puzzle via New Physics is irrelevant for solving the CP and rate puzzles related to tree-dominated decays. While some channels e.g. $K^-π^+,K^-ρ^0,π^+π^-,ρ^\pmπ…
Recently, the Belle collaboration measured the ratios of the branching fractions of the newly observed $Ω(2012)$ excited state. They did not observe significant signals for the $Ω(2012) \to \bar{K} Ξ^*(1530) \to \bar{K} πΞ$ decay, and reported an upper limit for the ratio of the three body decay to the two body decay mode of $Ω(2012) \to \bar{K} Ξ$. In this work, we revisit the newly observed $Ω(2012)$ from the molecular perspective where this resonance appears to be a dynamically generated state with spin-parity $3/2^-$ from the coupled channels interactions of the $\bar{K} Ξ^*(1530)$ and $ηΩ…
Single production of vector-like top partners is becoming a major focus of new searches, as the increasing mass limits on vector-like quarks obtained by the ATLAS and CMS collaborations are such that single production is becoming competitive with respect to pair production. Typically searches focus on decays containing leptons in the final state in order to have less background from the Standard Model processes. However the current centre of mass energies available in the latest LHC runs limit the searches to low masses. Fully hadronic final states may be an alternative option for discovery, a…
We point out that the null results of the hadronic electric dipole moment (EDM) searches constrain orbifold grand unified theories (GUTs), where the GUT symmetry and supersymmetry (SUSY) are both broken by boundary conditions in extra dimensions and it leads to rich fermion and sfermion flavor structures. A marginal chromoelectric dipole moment (CEDM) of the up quark is induced by the misalignment between the CP violating left- and right-handed up-type squark mixings, in contrast to the conventional four-dimensional SUSY GUTs. The up quark CEDM constraint is found to be as strong as those from…
We introduce a novel grooming procedure, which is an extension of the modified MassDrop tagging algorithm, tailored to the needs of deep inelastic scattering (DIS). The new algorithm, which grooms the event as a whole, takes advantage of the natural separation of current and target fragmentation in the Breit frame, in order to eliminate radiation in the beam and central rapidity regions. We study the groomed invariant mass in DIS and within soft-collinear effective theory we construct a factorization theorem for the cross-section in the back-to-back limit. In this limit we show that, up to a n…
Hadronic charmless B decays to scalar mesons are studied within the framework of QCD factorization (QCDF). Considering two different scenarios for scalar mesons above 1 GeV, we find that the data favor the scenario in which the scalars $a_0(1450)$ and $K_0^*(1430)$ are the lowest lying $q\bar q$ bound states. This in turn implies a preferred four-quark nature for light scalars below 1 GeV. Assuming $K_0^*(1430)$ being a lowest lying $q\bar s$ state, we show that the data of $B\to K_0^*(1430)η^{(')}$ and $B\to K_0^*(1430)(ρ,ω,ϕ)$ can be accommodated in QCDF without introducing power corrections…
Supersymmetry searches at the LHC are both highly varied and highly constraining, but the vast majority are focused on cases where the final-stage visible decays are prompt. Scenarios featuring superparticles with detector-scale lifetimes have therefore remained a tantalizing possibility for sub-TeV SUSY, since explicit limits are relatively sparse. Nonetheless, the extremely low backgrounds of the few existing searches for collider-stable and displaced new particles facilitates recastings into powerful long-lived superparticle searches, even for models for which those searches are highly non-…
The future Large Hadron Electron Collider (LHeC) would enable collisions of an intense electron beam with either protons or heavy ions at the High Luminosity-Large Hadron Collider (HL- LHC). With a center of mass energy greater than a TeV and a high luminosity, the LHeC would be a new-generation collider for deep-inelastic scattering (DIS) and a significant facility for precise Higgs physics, complementing pp and electron-positron colliders. Anomalous hadronic decay signatures of the Higgs Boson, such as those into three or more partons, are challenging to detect at the LHC due to high backgro…
Based on recent LHC Higgs analyses and in anticipation of future results we revisit theories where Higgs bosons can couple to weak gauge bosons with enhanced strength relative to the Standard Model value. Specifically, we look at the Georgi-Machacek model and its generalizations where higher "spin" representations of SU(2)_L break electroweak symmetry while maintaining custodial SU(2). In these theories, there is not only a Higgs-like boson but partner Higgs scalars transforming under representations of custodial SU(2), leading to a rich phenomenology. These theories serve as a consistent theo…
For this year's 8TeV run of the LHC we lay out different strategies to search for scalar top pairs. We show results for the hadronic and for the semi-leptonic channels based on hadronic top tagging. For the di-lepton channel we illustrate the impact of transverse mass variables. Each of our signal-to-background ratios ranges around unity for a stop mass around 400GeV. The combined signal significances show that dedicated stop searches are becoming sensitive over a non-negligible part of parameter space.
The global fit of the Standard Model to electroweak precision data, routinely performed by the LEP electroweak working group and others, demonstrated impressively the predictive power of electroweak unification and quantum loop corrections. We have revisited this fit in view of (i) the development of the new generic fitting package Gfitter, (ii) the insertion of constraints from direct Higgs searches at LEP and the Tevatron, and (iii) a more thorough statistical interpretation of the results. Gfitter is a modular fitting toolkit, which features predictive theoretical models as independent plug…
An important tool for interpreting LHC searches for new physics are simplified models. They are characterized by a small number of parameters and thus often rely on a simplified description of particle production and decay dynamics. We compare the interpretation of current LHC searches for hadronic jets plus missing energy signatures within simplified models with the interpretation within complete supersymmetric and same-spin models of quark partners. We found that the differences between the mass limits derived from a simplified model and from the complete models are moderate given the curren…
The addition of the QCD axion to the Minimal Supersymmetric Standard Model (MSSM) not only solves the strong CP problem but also modifies the dark sector with new dark matter candidates. While SUSY axion phenomenology is usually restricted to searches for the axion itself or searches for the ordinary SUSY particles, this work focuses on scenarios where the axion's superpartner, the axino, may be detectable at the Large Hadron Collider (LHC) in the decays of neutralinos displaced from the primary vertex. In particular, we focus on the KSVZ axino within the hadronic axion window. The decay lengt…
We consider a new technique for neutrino energy and topology reconstruction at DUNE. In particular, we show that when the direction of the incoming neutrino is known, one can use the measured directions of the outgoing leptonic and hadronic particles to reconstruct poorly-measured quantities, such as the hadronic cascade energy. We show that this alternative technique yields an energy resolution which is comparable to current reconstruction methods which sum measured energies. As a proof of concept we apply this new reconstruction method to a search for dark matter annihilation in the Sun. We …
Searches for new hadronic resonances typically focus on high-mass spectra, due to overwhelming QCD backgrounds and detector trigger rates. We present a study of searches for relatively low-mass hadronic resonances at the LHC in the case that the resonance is boosted by recoiling against a well-measured high-$p_{\textrm{T}}$ probe such as a muon, photon or jet. The hadronic decay of the resonance is then reconstructed either as a single large-radius jet or as a resolved pair of standard narrow-radius jets, balanced in transverse momentum to the probe. We show that the existing 2015 LHC dataset …
In this poster, we present a model of large extra dimensions where the internal space has the geometry of a hyperbolic disc. Compared with the ADD model, this model provides a more satisfactory solution to the hierarchy problem between the electroweak scale and the Planck scale, and it also avoids constraints from astrophysics. Since there is no known analytic form of the Kaluza-Klein spectrum for our choice of geometry, we obtain a spectrum based on a combination of approximations and numerical computations. We study the possible signatures of our model for hadron colliders, especially the LH…
We consider the hadronic radiation patterns for the generic process of bb + 2 forward jet production at the LHC, where the (centrally produced) bb originate either from a Higgs, a Z or from standard QCD production processes. A numerical technique for evaluating the radiation patterns for non-trivial final states is introduced and shown to agree with the standard analytic results for more simple processes. Significant differences between the radiation patterns for the Higgs signal and the background processes are observed and quantified. This suggests that hadronic radiation patterns could be u…
We discuss how molecule-based searches offer complementary probes to study the violation of fundamental symmetries. These experiments have the potential to probe not only the electron EDM, but also hadronic CPV phenomena. Future experimental developments will offer generic sensitivity to probe flavor neutral sources of both leptonic and hadronic CPV at scales of $\geq$ 100 TeV, and flavor changing CPV at scales of $\geq$ 1000 TeV.
Three-body semileptonic $τ$-decays offer a path to understand the properties of light hadronic systems and CP symmetry violations through searches for electric dipole moments. In studies of electro-weak physics, the hadronic part of the final states has traditionally been described using the language of form factors. Spectroscopic information, resolved in terms of orbital angular momentum quantum-numbers, is best being derived from an explicit decomposition of the hadronic current in the orbital angular momentum basis. Motivated by the upcoming large data samples from B factories, we present t…
We introduce three alternative angular variables-denoted by $\tildeω_\text{min}$, $\hatω_\text{min}$, and $χ_\text{min}$-for QCD multijet event suppression in supersymmetry searches in events with large missing transverse momentum in proton-proton collisions at the LHC at CERN. In searches in all-hadronic final states in the CMS and ATLAS experiments, the angle $Δφ_i$, the azimuthal angle between a jet and the missing transverse momentum, is widely used to reduce QCD multijet background events with large missing transverse momentum, which is primarily caused by a jet momentum mismeasurement or…
New particles at the TeV scale can decay hadronically with strongly collimated jets, thus the standard reconstruction methods based on invariant-masses of well-separated jets can fail. We discuss how to identify such particles in pp collisions at the LHC using jet shapes which help to reduce the contribution of QCD-induced events. We focus on a rather generic example X to ttbar to hadrons, with X being a heavy particle, but the approach is well suited for reconstruction of other decay channels characterized by a cascade decay of known states.
We present a generic method for improving the effectiveness of heavy particle searches in hadronic channels at the Large Hadron Collider. By selectively removing, or pruning, protojets from the substructure provided by a k_T-style jet algorithm, we improve the mass resolution for heavy decays and decrease the QCD background. We show that the protojets removed are typical of soft radiation and underlying event contributions, and atypical of accurately reconstructed heavy particles.
We consider experimental limits on colour triplet fermions that decay dominantly to three jets via a scalar mediator that can be on- or off-shell. These fermions arise in top-partner models that can solve the hierarchy problem, and limits on this scenario are weaker than those on traditional top-partner models because of the messy all-hadronic final state with significant backgrounds. We do find, however, that while there are no dedicated searches for this scenario, especially in case of an on-shell mediator, the suite of LHC all-hadronic searches still constrains a significant portion of the …
We explore the mono-$Z$ signature for dark matter searches at future high energy $e^+e^-$ colliders. In the context of effective field theory, we consider two kinds of contact operators describing dark matter interactions with electroweak gauge bosons and with electron/positron, respectively. For five benchmark models, we propose kinematic cuts to distinguish signals from backgrounds for both charged leptonic and hadronic decay modes of the $Z$ boson. We also present the experimental sensitivity to cutoff scales of effective operators and compare it with that of the Fermi-LAT indirect search a…
The search for an intermediate mass Higgs boson at the LHC needs the quantitative understanding of the two-photon background. A calculation of two-photon production in hadronic collisions at full next-to-leading order is described. It includes photons originating from the hadronization of QCD partons which play an important role at the LHC. A prediction for the invariant mass distribution for photon pairs at the LHC is presented and finally the residual scale dependencies are discussed.
The latest results from CMS on searches for supersymmetry are presented. Searches involving all-hadronic final states with jets and missing transverse energy, and in final states including one or more isolated leptons are discussed. The results are based on 19.5/fb of LHC proton-proton collisions at sqrt = 8 TeV taken with the CMS detector.
Motivated by the shift in experimental attention towards electroweak supersymmetric particle production at the CERN LHC, we update in this paper our precision predictions at next-to-leading order of perturbative QCD matched to resummation at the next-to-leading logarithmic accuracy for direct slepton pair production in proton-proton collisions. Simplified models, now commonly adopted by the experimental collaborations for selectrons and smuons as well as mixing staus, are used as benchmarks for total cross sections at achieved and future center-of-mass energies. They are presented together wit…
The sensitivity of Standard Model Higgs boson searches at the Tevatron experiments with a mass 135<MH<190 GeV using the channel H->WW->ll+MET (l=e,mu) is discussed. Three new event selections involving Higgs in association with one or two high PT hadronic jets are discussed. Using Leading Order Matrix Elements and a conservative cut-based analysis a 95% confidence level exclusion on sigmaxBR(H->WW), 1.6 times larger than that predicted by the Standard Model for MH=165 GeV, may be achieved with 5fb-1 of integrated luminosity. By combining these three event selections with the existing analysis,…
A method is proposed for distinguishing highly boosted hadronically decaying W's (W-jets) from QCD-jets using jet substructure. Previous methods, such as the filtering/mass-drop method, can give a factor of ~2 improvement in S/sqrt(B) for jet pT > 200 GeV. In contrast, a multivariate approach including new discriminants such as R-cores, which characterize the shape of the W-jet, subjet planar flow, and grooming-sensitivities is shown to provide a much larger factor of ~5 improvement in S/sqrt(B). For longitudinally polarized W's, such as those coming from many new physics models, the discrimin…
A method is introduced for distinguishing top jets (boosted, hadronically decaying top quarks) from light quark and gluon jets using jet substructure. The procedure involves parsing the jet cluster to resolve its subjets, and then imposing kinematic constraints. With this method, light quark or gluon jets with pT ~ 1 TeV can be rejected with an efficiency of around 99% while retaining up to 40% of top jets. This reduces the dijet background to heavy t-tbar resonances by a factor of ~10,000, thereby allowing resonance searches in t-tbar to be extended into the all-hadronic channel. In addition,…
Results of searches for SUSY production at CMS in events with third-generation signatures are presented. Along with missing energy, the final states may include hadronic jets with or without b-quark tag, light leptons, and tau leptons. These features serve both to distinguish standard-model components, and sensitivity to those SUSY models that lead to final states rich of heavy-flavored particles.
Abelian U(1) gauge group extensions of the Standard Model represent one of the most minimal approaches to solve some of the most urgent particle physics questions and provide a rich phenomenology in various experimental searches. In this work, we focus on baryophilic vector mediator models in the MeV-to-GeV mass range and, in particular, present, for the first time, gauge vector field decays into almost arbitrary hadronic final states. Using only very little theoretical approximations, we rigorously follow the vector meson dominance theory in our calculations. We study the effect on the total …
We introduce the `stealth bosons' $S$, light boosted particles with a decay $S \to AA \to q \bar q q \bar q$ into two daughter bosons $A$, which subsequently decay into four quarks that are reconstructed as a single fat jet. Variables that measure the two-pronged structure of fat jets, which are used for diboson resonance searches in hadronic or semi-leptonic final states, classify the jets produced in stealth boson decays as QCD-like - actually, for these variables they may seem more background-like than the QCD background itself. The number of tracks in those jets can also be, on average, mu…
We describe an effective theory of interaction between pairs of dark matter particles (denoted $χ$) and pairs of $W$ bosons. Such an interaction could accommodate $χ\barχ\rightarrow WW$ processes, which are a major focus of indirect dark matter experiments, as well as $pp \rightarrow W\rightarrow Wχ\barχ$ processes, which would predict excesses at the LHC in the $W$+MET final-state. We reinterpret an ATLAS $W$+MET analysis in the hadronic mode and translate the bounds to the space of indirect detection signals. We also reinterpret the $W$+MET analysis in terms of graviton theory through the pr…
A summary of the different searches for weakly produced SUSY by both CMS and ATLAS is presented here. A review on the methodology of these searches, including event selection, background suppression and estimation methods, etc is covered. Other searches at the LHC already probe squarks and gluino masses up to 1.4 TeV, such scenario, may favour electroweak production of charginos and neutralinos, that will produce many-lepton final states accompanied by E$_{\rm T}^{\rm miss}\,$ and very little hadronic activity. Latest searches include Higgs boson in the decay and exploits VBF associated produc…
This Letter presents a study of the reconstruction and identification of $H\to WW^*$ with high transverse momentum, where both $W^{(*)}$ bosons decay hadronically. We show that the boosted $H\to WW^*$ can be effectively reconstructed as a single jet and identified using jet substructures in the center-of-mass frame of the jet. Such a reconstruction and identification approach can discriminate the boosted $H\to WW^*$ in the full hadronic final state from QCD jets. This result will significantly improve experimental sensitivities of searches for potential new physics phenomena beyond the standar…
We show that the relatively small but coincident excesses observed around 2 TeV in the ATLAS Run 1 and Run 2 hadronic diboson searches --- when a cut on the number of tracks in the fat jets is not applied --- and the null results of all remaining high-mass diboson searches are compatible with the decay of a triboson resonance $R$ into $WZ$ plus an extra particle $X$. These decays can take place via new neutral ($Y^0$) or charged ($Y^\pm$) particles, namely $R \to Y^0 \, W$, with $Y^0 \to Z X$, or $R \to Y^\pm Z$, with $Y^\pm \to W X$. An obvious candidate for such intermediate particle is a ne…
Searches for dark photons provide serendipitous discovery potential for other types of vector particles. We develop a framework for recasting dark photon searches to obtain constraints on more general theories, which includes a data-driven method for determining hadronic decay rates. We demonstrate our approach by deriving constraints on a vector that couples to the $B\!-\!L$ current, a leptophobic $B$ boson that couples directly to baryon number and to leptons via $B$-$γ$ kinetic mixing, and on a vector that mediates a protophobic force. Our approach can easily be generalized to any massive g…
Charged Higgs boson may be produced at hadron colliders via the decay of top quarks. At the LHC, The large production cross section of top quarks pairs will make it one of the earliest channels allowing to search for physics beyond the standard model. Assuming the decay $H^+ \to τ^+ν$, previous searches have so far considered only hadronic tau decays. Here we show that by using appropriate kinematical variables (transverse mass observables), leptonic tau decays can be used as well, for both observing and possibly measuring the mass of the charged Higgs boson. This can increase the overall expe…
It is very easy to write down models in which long-lived particles decaying to standard model states are pair-produced via Higgs decays, resulting in the signature of approximately back-to-back pairs of displaced narrow hadronic jets and/or lepton jets at the LHC. The LHC collaborations have already searched for such signatures with no observed excess. This paper describes a Monte Carlo method to reinterpret the searches. The method relies on (ideally multidimensional) efficiency tables, thus we implore collaborations to include them in any future work. Exclusion regions in mixing-mass paramet…
Precision experimental tests of the Standard Model of particle physics (SM) are one of our best hopes for discovering what new physics lies beyond the SM (BSM). Key in the search for new physics is the connection between theory and experiment. Forging this connection for searches involving low-energy hadronic or nuclear environments requires the use of a non-perturbative theoretical tool, lattice QCD. We present two recent lattice QCD calculations by the CalLat collaboration relevant for new physics searches: the nucleon axial coupling, $g_A$, whose precise value as predicted by the SM could h…
The ATLAS collaboration has recently reported a 2.6 sigma excess in the search for a heavy resonance decaying into a pair of weak gauge bosons. Only fully hadronic final states are being looked for in the analysis. If the observed excess really originates from the gauge bosons' decays, other decay modes of the gauge bosons would inevitably leave a trace on other exotic searches. In this paper, we propose the use of the Z boson decay into a pair of neutrinos to test the excess. This decay leads to a very large missing energy and can be probed with conventional dark matter searches at the LHC. W…
