We consider a dark sector containing a pair of almost degenerate states coupled to the Standard Model through a dark photon mediator. This set-up constitutes a simple realization of the inelastic dark matter scenario. The heaviest dark state is long-lived, in the limit of a small kinetic mixing among the dark photon and the Standard Model hypercharge gauge boson, and/or of a small mass splitting among the dark states. We study the prospects for detection of this scenario at proposed LHC experiments dedicated to search for long-lived particles, namely FASER, MATHUSLA, CODEX-b, AL3X, MAPP, ANUBIS and FACET. We consider both the cases of fermionic and scalar inelastic dark matter. We show that these experimental facilities can probe unexplored regions of the parameter space of this model, and we highlight their complementary roles.
In this paper we discuss exclusive reactions which analysis can be used to receive direct indication of diquark existence. We make estimations of diquark scattering process measurement in inelastic proton-proton collisions. It was shown that putting special restrictions over kinematics and particles in final state of process it will be possible to enhance potential diquark contribution to scattering up to $10^4$. We put qualitative characteristics of process with diquark and ways to distinguish it from quark scattering in model-independent way.
We study the impact of a hidden sector beyond the Standard Model, e.g. a Hidden Valley model, on factorial moments and cumulants of multiplicity distributions in multiparticle production with a special emphasis on the prospects for LHC results.
In this talk, I describe the general characteristics of radiative neutrino mass models that can be probed at the LHC. I then cover the constraints on a new, explicit model of this type.
We demonstrate that the detection of the SM and MSSM Higgs bosons will be possible at the LHC via $t\anti t b\anti b$ and $b\anti b b\anti b$ final state, provided $b$-tagging can be performed with good efficiency and purity.
Following a general introduction to open questions beyond the Standard Model, the prospects for addressing them in the new era opened up by the LHC are reviewed. Sample highlights are given of ways in which the LHC is already probing beyond previous experiments, including the searches for supersymmetry, quark and gluon substructure and microscopic black holes.
Most signatures of new physics in colliders have been studied so far on the transverse plane with respect to the beam direction. In this work however we study the impact of a hidden sector beyond the Standard Model (SM) on inclusive (pseudo)rapidity correlations and moments of the multiplicity distributions, with special emphasis in the LHC results.
We investigate the sensitivity of the heavy ion mode of the LHC to anomalous Higgs boson couplings to photons, H-photon-photon, through the analysis of the processes photon photon to b anti-b and photon photon to photon photon in peripheral heavy ion collisions. We suggest cuts to improve the signal over background ratio and determine the capability of LHC to impose bounds on anomalous couplings by searching for a Higgs boson signal in these modes.
We discuss expectations for the total and inelastic cross-sections at LHC CM energies $\sqrt{s}\ =\ 7\ TeV$ {and $ 14\ TeV$} obtained in an eikonal minijet model augmented by soft gluon $k_t$-resummation, which we describe in some detail. We present a band of predictions which encompass recent LHC data and suggest that the inelastic cross-section described by two channel eikonal models include only uncorrelated processes. We show that this interpretation of the model is supported by the LHC data.
These TASI lectures consider low mass hidden sectors from Hidden Valleys, Quirks and Unparticles. We show how each corresponds to a different limit of the same class of models: hidden sectors with non-abelian gauge groups with mass gaps well below a TeV that communicate to the Standard Model through weak scale suppressed higher dimension operators. We provide concrete examples of such models and discuss LHC signatures. Lastly we turn to discussing the application of Hidden Valleys to dark matter sectors.
Weak boson fusion is a copious source of intermediate mass Higgs bosons at the LHC, with a rate sigma*B(H -> gamma gamma) of up to 9 fb. The additional very energetic forward jets in these events provide for a unique signature. A parton level analysis of the dominant backgrounds demonstrates that this channel allows the observation of H -> gamma gamma in a low background environment, with modest luminosity.
In this paper we investigate the LHC potential for discovering doubly-charged vector bileptons considering the measurable process $p,p$ $\rightarrow$ $e^{\mp}e^{\mp}μ^{\pm}μ^{\pm} X$. We perform the study using four different bilepton masses and three different exotics quark masses. Minimal LHC integrated luminosities needed for discovering and for setting limits on bilepton masses are obtained for both 7 TeV and 14 TeV center-of-mass energies. We find that these spectacular signatures can be observed at the LHC in the next years up to a bilepton mass of order of 1 TeV.
Analyzing recent ALICE data on inelastic pp scattering at the LHC energies we show that charged particle distributions exhibit geometrical scaling (GS). We show also that the inelastic cross-section is scaling as well and that in this case the quality of GS is better than for multiplicities. Moreover, exponent $λ$ characterizing the saturation scale is for the cross-section scaling compatible with the one found in deep inelastic ep scattering at HERA. Next, by parametrizing charged particles distributions by the Tsallis-like formula, we find a somewhat unexpected solution that still exhibits G…
Present status of experimental studies of inelastic diffraction at the Large Hadron Collider is analysed. Impact of the current uncertainties concerning the diffraction rate on the predicted extensive air shower development is investigated. Relation to studies of the primary composition of ultrahigh energy cosmic rays is illustrated by comparing numerical simulation results to the data of the Telescope Array experiment on the distributions of the shower maximum position.
We analyze the decays to muons of a light dilaton produced via vector boson fusion at the LHC. We investigate models in which the electroweak symmetry breaking is triggered by a spontaneously broken, approximately conformal sector. Taking into account the possibility of shifts in the dilaton Yukawa couplings to muons, we find a rather promising scenario for the conformal model search in the channel, with the possibility for a dilaton discovery at a delivered luminosity of 100 fb-1 at the LHC or, alternatively, for an extension of the exclusion zone in the model parameter space, until now fixed…
Using a peculiar version of the SU(3)L x U(1)N electroweak model, we investigate the production of doubly charged Higgs boson at the Large Hadron Collider. Our results include branching ratio calculations for the doubly charged Higgs and for one of the neutral scalar bosons of the model.
The production of a neutral, CP even Higgs via weak boson fusion and decay H -> tau tau at the LHC is studied for the Standard Model and MSSM, utilizing a parton level Monte Carlo analysis. This channel allows a 5 sigma observation of a Standard Model Higgs with an integrated luminosity of about 30 fb^-1, and provides a direct measurement of the H-tau-tau coupling. For the MSSM case, a highly significant signal for at least one of the Higgs bosons with reasonable luminosity is possible over the entire physical parameter space which will be left unexplored by LEP2.
We discuss the prospects of searching for the neutral Higgs bosons of the triplet model in central exclusive production at the LHC. A detailed Monte Carlo analysis is presented for six benchmark scenarios for the Higgs boson, $H_1^{0}$, these cover $m_{H_1^0}=$~120, 150 GeV and doublet-triplet mixing of $c_H=$~0.2, 0.5 or 0.8. We find that, for appropriate values of $c_H$, an excellent Higgs mass measurement is possible for the neutral Higgs in the triplet model, and discuss how to distinguish the triplet model Higgs boson from the Higgs boson of the Standard Model.
We consider LHC searches for dark matter in the mono-Higgs channel using the tools of effective field theory. This channel takes unique advantage of the presence of $SU(2)_L$ breaking in those operators to avoid the need for any initial-state radiation, usually necessary to tag the production of invisible particles. We find that sensitivities to parameters describing dark matter interactions with standard model particles are comparable to those from monojet searches for a subset of the usually-considered operators, and we present for the first time bounds from collider searches on operators wh…
Heavy Neutral Leptons are naturally present in many well-motivated extensions of the Standard Model. If their mass is of few dozens of GeVs, they can be long-lived and lead to events with displaced vertices, giving rise to promising signatures due to the low background. We revisit the opportunities offered by the LHC to discover these long-lived states via searches with displaced vertices. We study in particular the implication on the parameter space sensitivity when all mixings to active flavors are taken into account.
Recent results for the total and inelastic hadronic cross-sections from LHC experiments are compared with predictions from a single channel PDF driven eikonal mini-jet model and from an empirical model. The role of soft gluon resummation in the infrared region in taming the rise of mini-jets and their contribution to the increase of the total cross-sections at high energies are discussed. Survival probabilities at LHC, whose theoretical estimates range from circa 10 percent to a few per mille, will be estimated in this model and compared with results from QCD inspired models and from multi cha…
The study of ep-scattering at LEP x LHC offers an interesting opportunity to search for additional heavy neutral gauge bosons. We study the influence of radiative corrections, especially of the potentially large QED contributions, to the expected cross sections. These corrections are typically of the same order as the effect searched for or even larger and have to be taken into account properly.
We discuss the feasibility of the observation of the signal from $B_c$ mesons in the ATLAS experiment of the LHC collider at a luminosity of ${\approx}\ 10^{33}$cm$^{-2}$s$^{-1}$. In particular we address the decay mode $B_c{\rightarrow}J/ψπ$ followed by the leptonic decay $J/ψ{\rightarrow}μ^+μ^-$, which should permit an accurate measurement of the $B_c$ mass. We performed a Monte Carlo study of the signal and background concluding that a precision of $40$ MeV for the $B_c$ mass could be achieved after one year of running.
Despite rather long-term theoretical and experimental studies, the hypothesis of the non-zero intrinsic (or valence-like) heavy quark component of the proton distribution functions has not yet been confirmed or rejected. The LHC with $pp$-collisions at $\sqrt{s}=$ 7--14 TeV will obviously supply extra unique information concerning the above-mentioned component of the proton. To use the LHC potential, first of all, one should select the parton-level (sub)processes (and final-state signatures) that are most sensitive to the intrinsic heavy quark contributions. To this end inclusive production of…
In the light of recent experimental results from IceCube, LHC searches for scalar leptoquark, and the flavor anomalies $R_K$ and $R_{K^*}$, we analyze two scalar leptoquark models with hypercharge $Y=1/6$ and $Y=7/6$. We consider the 53 high-energy starting events from IceCube and perform a statistical analysis, taking into account both the Standard Model and leptoquark contribution together. The lighter leptoquark states that are in agreement with IceCube are strongly constrained from LHC di-lepton+dijet search. Heavier leptoquarks in the TeV mass range are in agreement both with IceCube and …
We discuss the high-energy dependencies of diffractive and non-diffractive inelastic cross-sections in view of the recent LHC data which revealed a presence of the reflective scattering mode.
In this work, we analyse and demonstrate possible strategies to explore extended Higgs sector of the Minimal Supersymmetric Standard Model (MSSM). In particular we concentrate on heavy Higgs decays to electroweakinos. We analyse the Higgs to electroweakino decays in the allowed MSSM parameter space after taking into account 13 TeV LHC searches for supersymmetric particles and phenomenological constraints such as flavour physics, Higgs measurements and dark matter constraints. We explore some novel aspects of these Higgs decays. The final states resulting from Higgs to electroweakino decays wil…
We present a strategy for searching for heavy neutrinos at the Large Hadron Collider using the MoEDAL Experiment's MAPP detector. We hypothesize the heavy neutrino to be a member of a fourth generation lepton doublet, with the electric dipole moment (EDM) introduced within a dimension-five operator. In this model the heavy neutrino is produced in association with a heavy lepton. According to our current experimental and theoretical understanding, the electric dipole moment of this heavy neutrino may be as high as $10^{-15}$ $e$ cm. Taking advantage of the sensitivity of MoEDAL detector, we exa…
Composite Higgs models predict the existence of resonances. We study in detail the collider phenomenology of both the vector and fermionic resonances, including the possibility of both of them being light and within the reach of the LHC. We present current constraints from di-boson, di-lepton resonance searches and top partner pair searches on a set of simplified benchmark models based on the minimal coset $SO(5)/SO(4)$, and make projections for the reach of the HL-LHC. We find that the cascade decay channels for the vector resonances into top partners, or vice versa, can play an important rol…
We investigated the energy dependence of the parton-parton inelastic cross sections, parton- parton inelastic overlap functions and the Cq moments in proton interactions from 10 to 14000 GeV. The used approach is based on a phenomenological procedure where elastic and inelastic proton observables are described in a connected way by exploring the unitarity of S- Matrix. Applying a Quantum Chromodynamics inspired eikonal model, that contains contributions of the quark-quark, quark-gluon and gluon-gluon interactions, theoretical predictions on inelastic cross sections and Cq moments are compared …
We reexamine the prospects for searching for a neutral Higgs boson in the intermediate-mass range and physics beyond the standard model, using the proton- and ion-beam facilities of the LHC to study coherent two-photon processes. Considering realistic design luminosities for the different ion beams, we find that beams of light-to-medium size ions like calcium will give the highest production rates. With a suitable trigger and assuming a b-quark identification efficiency of $30\%$ and a $b{\bar b}$ mass resolution of 10 GeV one could expect to see a Higgs signal in the $b{\bar b}$ channel with …
The existence of an axion-like particle (ALP) would induce anomalous scattering of light by light. This process can be probed at the Large Hadron Collider in central exclusive production of photon pairs in proton-proton collisions by tagging the surviving protons using forward proton detectors. Using a detailed simulation, we estimate the expected bounds on the ALP--photon coupling for a wide range of masses. We show that the proposed search is competitive and complementary to other collider bounds for masses above 600 GeV, especially for resonant ALP production between 600 GeV and 2 TeV. Our …
We suggest that, if current measurements of inclusive jet production for central rapidities at the LHC are extended to lower transverse momenta, one could define a visible cross section sensitive to the unitarity bound set by the recent determination of the inelastic proton-proton cross section.
We show that the onset and rise of QCD mini-jets provide the dynamical mechanism behind the appearance of a soft edge in pp collisions around ISR energies and thus such a soft edge is built in our mini-jet model with soft gluon resummation. Here the model is optimized for LHC at $\sqrt{s} = 7, 8 TeV$ and predictions made for higher LHC and cosmic ray energies. Further, we provide a phenomenological picture to discuss the breakup of the total cross-section into its elastic, uncorrelated and correlated inelastic pieces in the framework of a one-channel eikonal function.
Over the last years, new physics in terms of a novel weakly-interacting massive particle (WIMP) has come more and more under pressure from experimental null results. While the remaining WIMP parameter space will be probed by next generation dark matter experiments, models of light new physics have become increasingly popular over the last decade. In an effort to explore the parameter space of such light physics, a myriad of custom designed high-precision/low-energy experiments has been proposed. In this note, however, I argue that existing LHC multipurpose experiments like ATALS and CMS have a…
Fermion masses may arise via mixing of elementary fermions with composite fermions of a strong sector in scenarios of strongly-coupled electroweak symmetry breaking. The strong sector may contain leptoquark states with masses as light as several hundred GeV. In the present study we focus on the scalar modes of such leptoquarks since their bosonic couplings are determined completely and hence their production cross sections only depend on their masses. We study all the possible gauge-invariant non-derivative and single-derivative couplings of the scalar leptoquarks to the quarks and leptons, wh…
There seem to be recently an evidence for $C = -1$ odderon exchange in proton-proton elastic scattering at high energies. Here we discuss three different central-exclusive-production processes $pp \to pp (ϕ\to K^{+}K^{-})$, $pp \to pp (ϕ\to μ^{+}μ^{-})$, and $pp \to pp ϕϕ\to pp K^{+}K^{-}K^{+}K^{-}$, as a possible source of information for soft odderon exchange. The theoretical results are calculated within the tensor-pomeron and vector-odderon model for soft reactions. We include absorptive corrections at the amplitude level. To describe the low-energy data measured in the past by the WA102 c…
The $J/ψ$ production originating from elastic and inelastic photoproduction processes in p-p collisions at LHC energies is investigated, where the fragmentation processes are involved. An exact treatment is performed, which adopts the Martin-Ryskin method to weight the contribution from different channels, and can return to Weizsäcker-Williams approximation (WWA) when $Q^{2}\rightarrow0$. The relevant kinematical relations are also achieved. We present a comprehensive analysis for the feature of WWA by comparing with the exact treatment. The results are expressed in $Q^{2}$, $y$, $z$, $p_{T}$,…
The CP-odd Higgs boson $A^0$ of the Minimal Supersymmetric Standard Model (MSSM) and Two Higgs Doublet Model (2HDM) will usually decay into the heaviest possible fermion -- antifermion pair available. The $A^0 \to VV$ decay where, $V =γ, Z, W^\pm$, and gluons are of particular interest as they are not allowed at tree level and hence they may offer information about the underlying new physics that enters at one loop level. In this paper all branching ratios of the CP-odd Higgs boson $A^0$ both in the MSSM and 2HDM are presented for this channel including all relevant Standard Model (SM) and MSS…
We discuss the double-parton scattering (DPS) effects in four-jet production at the LHC. A special attention is given to the optimization of kinematical conditions in order to enhance the relative contribution of DPS in four-jet sample. The calculations of single-parton and double-parton scattering components are done in the high-energy (or $k_{T}$)-factorization approach. Here we follow our recent developments of relevant methods and tools that are implemented in the AVHLIB Monte Carlo library. Several differential distributions are calculated and carefully discussed in the context of recent …
Weak boson fusion is a copious source of intermediate mass Higgs bosons at the LHC. The additional very energetic forward jets in these events provide for powerful background suppression tools. We analyze the $H \to ττ$ decay mode for the Standard Model Higgs boson. A parton level analysis of the dominant physics backgrounds (mainly $Z \to ττ$ and Drell-Yan production of $τ$'s) and of reducible backgrounds (from $W+$ jet and $b\bar{b}$ production in association with two jets and subsequent leptonic decays) demonstrates that this channel allows the observation of $H \to ττ$ in a low background …
A simple model for elastic diffractive hadron scattering, reproducing the dip-bump structure is used to analyze PP and $\bar PP$ scattering. The main emphasis is on the delicate and non-trivial dynamics in the dip-bump region, near t=-1 GeV$^2$. The simplicity of the model and the expected smallness of the absorption corrections enables one the control of various contributions to the scattering amplitude, in particular the interplay between the C-even and C-odd components of the amplitude, as well as their relative contribution, changing with s and t. The role of the non-linearity of the Regge…
We perform a model-independent study of inelastic dark matter at the LHC, concentrating on the parameter space with the mass splitting between the excited and ground states of dark matter above a few hundred MeV, where the direct detection experiments are unlikely to explore. The generic signatures of inelastic dark matter at the LHC are displaced pions together with a monojet plus missing energy, and can be tested at the 7 TeV LHC.
We discuss the feasibility of the observation of the signal from $B_c$ mesons in the ATLAS experiment at the LHC. In particular, we address the decay mode $B_c{\rightarrow}J/ψπ$ followed by the leptonic decay $J/ψ{\rightarrow}μ^+μ^-$, which should permit an accurate measurement of the $B_c$ mass. We performed a Monte Carlo study of the signal and background concluding that a precision of $\approx$ 1 MeV for the $B_c$ mass could be achieved after one year of running at $\lq\lq$low" luminosity. The semileptonic decay $B_c{\rightarrow}J/ψ μ^+ν_μ$ is also considered for a possible extraction of ${…
These lectures on Higgs boson collider searches were presented at TASI 2006. I first review the Standard Model searches: what LEP did, prospects for Tevatron searches, the program planned for LHC, and some of the possibilities at a future ILC. I then cover in-depth what comes after a candidate discovery at LHC: the various measurements one has to make to determine exactly what the Higgs sector is. Finally, I discuss the MSSM extension to the Higgs sector.
We discuss thw relations between the elastic and inelastic cross-sections valid for the shadow and reflective modes of the elastic scattering. Considerations are based on the unitarity arguments. It is shown that the redistribution of the total interaction probability between the elastic and inelastic interactions can lead to increasing ratio of $σ_{el}(s)/σ_{tot}(s)$ at the LHC energies in presence of the reflective scattering mode. The form of the inelastic overlap function becomes peripheral due to the negative feedback. In the absorptive scattering mode, the mechanism of this increase is a…
The possibility to simulate lepton number violating supersymmetric models has been introduced into the recently updated PYTHIA event generator, now containing 1278 decay channels of SUSY particles into SM particles via lepton number violating interactions. This generator has been used in combination with the ATLFAST detector simulation to study the impact of lepton number violation (LV) on event topologies in the ATLAS detector, and trigger menus designed for LV-SUSY are proposed based on very general considerations. In addition, a rather preliminary analysis is presented on the possibility fo…
Heavy long-lived multi-charged leptons (MCLs) are predicted by various new physics models. These hypothetical MCLs can form bound states, due to their high electric charges and long life times. In this work, we propose a novel strategy of searching for MCLs through their bound state productions and decays. By utilizing LHC-8 TeV data in searching for resonances in the diphoton channel, we exclude the masses of isospin singlet heavy leptons with electric charge $|q|\geq 6$ (in units of electron charge) lower than $\sim$1.2 TeV, which are much stronger than the corresponding 8 TeV LHC bounds fro…
We discuss the search for the heavy charged Higgs bosons H^\pm, implicitly of the Minimal Supersymmetric Standard Model, in the tau-nu decay mode at the LHC. Compared to the dominant decay mode H^\pm\to bt, the channel suffers from suppression due to the branching ratio and the lack of direct mass reconstruction, but the reduced QCD background makes it a feasible channel especially in the large tan(beta) region. We study the production in `bt fusion' via bg\to tH^-, and the leading irreducible background bg\to tW^-. Our results indicate that for the H^\pm mass of greater than 200 GeV and up to…
We consider LHC searches for dilepton resonances in an intermediate mass range, $\sim 10 -80$ GeV. We adopt a kinetically mixed $Z'$ as an example of weakly coupled new physics that might have evaded detection at previous experiments but which could still be probed by LHC dilepton spectrum measurements in this mass range. Based on Monte Carlo simulations, we estimate that existing data from the 7 and 8 TeV LHC could be used to test values of the kinetic mixing parameter $ε$ several times smaller than precision electroweak upper bounds, were an appropriate analysis to be carried out by one of t…
We investigate a mono-Z process as a potential dark matter search strategy at the LHC. In this channel a single Z boson recoils against missing transverse momentum, attributed to dark matter particles, $χ$, which escape the detector. This search strategy is related, and complementary to, monojet and monophoton searches. For illustrative purposes we consider the process $q\bar{q} -> χχZ$ in a toy dark matter model, where the Z boson is emitted from either the initial state quarks, or from the internal propagator. Among the signatures of this process will be a pair of muons with high pT that rec…
New phenomena involving pseudorapidity and azimuthal correlations among final state particles in $pp$ collisions at the LHC can hint at the existence of hidden sectors beyond the Standard Model. In this paper we rely on a correlated-cluster picture of multiparticle production, which was shown to account for the ridge effect, to assess the effect of a hidden sector on three-particle correlations concluding that there is a potential signature of new physics that can be directly tested by experiments using well-known techniques.
We discuss many new subleading processes for inclusive production of W+W- pairs generally not included in the literature so far. We focus mainly on photon-photon induced processes. We include elastic-elastic, elastic-inelastic, inelastic-elastic and inelastic-inelastic contributions. Predictions for the total cross section and differential distributions in W - boson rapidity and transverse momentum as well as WW invariant mass are presented. The gamma-gamma components only constitute about 1-2 percent of the inclusive W+W- cross section but increases up to about 10 percent at large W+W- transv…
We study the heavy charged Higgs boson (from 800 GeV to 1500 GeV in this study) in production associated with a top quark at the LHC with the collision energy $\sqrt{s}=14$ TeV. Such a heavy charged Higgs boson can dominantly decay into a top quark and a bottom quark due to its large Yukawa couplings, like in MSSM. To suppress background events and to confirm the signal, we reconstruct the mass bumps of the heavy charged Higgs boson and the associated top quark. For this purpose, we propose a hybrid-R reconstruction method which utilizes the top tagging technique, a jet substructure technique …
