We explore possible signatures for right-handed neutrinos in TeV scale B-L extension of the Standard Model (SM) at the Large Hadron Collider (LHC). The studied four lepton signal has a tiny SM background. We find the signal experimentally accessible at LHC for the considered parameter regions.
We discuss the phenomenology of right-handed charged currents in the framework of the Standard Model Effective Field Theory, in which they arise due to a single gauge-invariant dimension-six operator. We study the manifestations of the nine complex couplings of the $W$ to right-handed quarks in collider physics, flavor physics, and low-energy precision measurements. We first obtain constraints on the couplings under the assumption that the right-handed operator is the dominant correction to the Standard Model at observable energies. We subsequently study the impact of degeneracies with other B…
Right-handed neutrinos offer us the possibility of accommodating neutrino masses. In a supersymmetric model, this implies the existence of right-handed sneutrinos. Right-handed sneutrinos are expected to be as light as other supersymmetric particles if the neutrinos are Dirac fermions, or if the lepton-number breaking scale is at (or below) the supersymmetry (SUSY) breaking scale, assumed to be around the electroweak scale. Depending on the mechanism of SUSY breaking, the lightest right-handed sneutrino may be the lightest supersymmetric particle (LSP). We consider the unique hadron collider s…
We examine lepton flavor violating (LFV) interactions for heavy right-handed neutrinos that exist in most of the standard model extensions that address dark matter (DM) and neutrino mass at the loop level. In order to probe the collider effect of these LFV interactions, we impose the assumption that the model parameters give the right values of the DM relic density and fulfill the constraints from the LFV processes $\ell_α\rightarrow\ell_βγ$ and $\ell_α\rightarrow3\ell_β$. We also investigate the possibility of probing these interactions, and hence the right-handed neutrino, at leptonic collid…
We propose a model with the left-handed and right-handed continuous Abelian gauge symmetry; $U(1)_L\times U(1)_R$. Then three right-handed neutrinos are naturally required to achieve $U(1)_R$ anomaly cancellations, while several mirror fermions are also needed to do $U(1)_L$ anomaly cancellations. Then we formulate the model, and discuss its testability of the new gauge interactions at collider physics such as the large hadron collider (LHC) and the international linear collider (ILC). In particular, we can investigate chiral structure of the interactions by the analysis of forward-backward as…
The breaking of parity, a fundamental symmetry between left and right is best understood in the framework of left-right symmetric extension of the standard model. We show that the production of a heavy right-handed neutrino at the proposed Large Hadron-Electron Collider (LHeC) could give us the most simple and direct hint of the scale of this breaking in left-right symmetric theories. This production mode gives a lepton number violating signal with $ΔL=2$ which is very clean and has practically no standard model background. We highlight that the right-handed nature of $W_R$ exchange which defi…
We propose a low energy extension of the Standard Model consisting of an additional gauged $U(1)_{B-L}$ plus three right-handed neutrinos. The lightest right-handed neutrinos have TeV scale masses and may be produced at colliders via their couplings to the $Z_{B-L}$ gauge boson whose mass and gauge coupling is constrained by the out-of-equilibrium condition leading to upper bounds on the right-handed neutrino and $Z_{B-L}$ production cross-sections at colliders. We propose a brane-world scenario which motivates such TeV mass right-handed neutrinos. Our analysis opens up the possibility that th…
We show that the associated production $pp\to W^{\prime}W$, and the rare decay $pp\to W'\to \bar\ell\ell W$ are useful tests of $W'$ couplings to fermions at future hadron colliders. For $M_{W'}\sim (1 - 3)$ TeV they would allow a clean determination on whether the $W'$ couples to $V-A$ or $V+A$ currents. As an illustration a model in which the $W^{\prime\pm}$ couples only to $V-A$ currents is contrasted to the left-right symmetric models which involve $V+A$ currents.
We discuss hadronic EDM constraints on the neutrino sector in the SUSY SU(5) GUT with the right-handed neutrinos. The hadronic EDMs are sensitive to the right-handed down-type squark mixings, especially between the second and third generations and between the first and third ones, compared with the other low-energy observables, and the flavor mixings are induced by the neutrino Yukawa interaction. The current experimental bound of the neutron EDM may imply that the right-handed tau neutrino mass is smaller than about 10^{14} GeV in the minimal supergravity scenario, and it may be improved furt…
It has been argued in the literature that the search for the slepton oscillation phenomenon can be a powerful probe of intergenerational mixing between sleptons, once sleptons are found at future colliders. In this article we estimate possible reach of future lepton colliders in probing left-handed slepton flavor mixing, especially mixing between the first and third generations, on which constraints imposed by other processes like $τ\to e γ$ are very weak. $e^+e^-$ collider is suitable for this purpose, since it can produce, if kinematically allowed, sleptons of the first generation via t-chan…
In the context of general $SU(2)_L\otimes SU(2)_R\otimes U(1)$ models a relatively light W' is still allowed in some scenarios with a heavy right-handed neutrino and a quark mixing matrix $U^R$ close to unity. We explore the consequences of the presence of this new charged current on the parity violating spin asymmetries which could be induced in one-jet inclusive production in polarized proton-proton or proton-neutron collisions. Such measurements could be performed within a few years at the Brookhaven Relativistic Heavy Ion Collider (RHIC) running part of the time as a polarized hadronic col…
In this article I review some connections between flavor physics and collider physics. The first part discusses the effect of right-handed charged currents on the determination of the CKM elements V_ub. It is shown that such an effective right-handed W-coupling can be generated in the MSSM which would lead to a sizable enhancement of single-top production at the LHC. The second part of this article focuses on the constraints on the mass splitting between left-handed squarks from Kaon and D mixing. Such a mass splitting has interesting consequences for squark decay chains at colliders.
Combining the cosmological requirement on dark matter with the recent BNL g-2 measurement it is argued that, within the mSUGRA framework, the preferred region for SUSY mass parameters falls well inside the area covered by the future linear colliders under consideration for right handed sleptons and of the 2 lightest neutralinos. The coverage for the lightest chargino and left handed sleptons is also favoured but with smaller confidence.
The Standard Model of particle interactions is extended to include fermion doublets (n,e)_R transforming under the gauge group SU(2)_R such that n is a scotino (dark-matter fermion), with odd R parity. This dark left-right model (DLRM) treats neutrinos and scotinos in parallel, and has interesting phenomenology at the Large Hadron Collider (LHC).
The inclusion of heavy neutral leptons (right-handed neutrinos) to the Standard Model (SM) particle content is one of the best motivated ways to account for the observed neutrino masses and flavor mixing. The modification of the charged and neutral currents from active-sterile mixing of the neutral leptons can provide novel signatures which can be tested at the future collider experiments. In this article, we explore the discovery prospect of a very heavy right handed neutrino to probe such extensions at the future collider experiments like Large Hadron electron Collider (LHeC) and liner colli…
In this paper we discuss the consequences of including a new heavy right-handed neutrino singlet $N_R$ in the littlest Higgs model. This new state is not connected with the light neutrinos {\it via} the seesaw mechanism. A very interesting property of this extended model is the full coupling of the new neutral gauge boson $A_H$ to $N_R$, giving large total cross sections and suggesting a wide range of experimental search for the $N_R$ at the p p collider CERN-LHC and future electron-positron collider ILC.
Recent lattice determinations of direct CP violation in kaon decays, parametrized by $ε'$, suggest a discrepancy of several sigma between experiment and the standard model. Assuming that this situation is due to new physics, we investigate a solution in terms of right-handed charged currents. Chiral perturbation theory, in combination with lattice QCD results, allows one to accurately determine the effect of right-handed interactions on $ε'$. In addition, similar techniques provide a direct link between the right-handed contributions to $ε'$ and hadronic electric dipole moments. We demonstrate…
We study the possible signature for lepton-flavor violation processes in the scalar-lepton sector of the minimal supersymmetric model at future electron-photon colliders. We find that an $\egm$ collider can provide a good opportunity to probe the mass differences and flavor mixing angles between the sleptons of the first generation and the other two generations for the right-handed as well as the left-handed sector. The sensitivity reach for lepton-flavor violation is comparable to that obtained at an $e^+e^-$ and $e^-e^-$ collider, and is significantly better than the current bound from low-e…
While it is natural for supersymmetric particles to be well within the mass range of the large hadron collider, it is possible that the sparticle masses could be very heavy. Signatures are examined at a very high energy hadron collider and an very high luminosity option for the Large Hadron Collider in such scenarios.
The Super-Kamiokande atmospheric neutrino data suggest existence of the large lepton-flavor violating (LFV) interaction in the higher energy scale. If the minimal supersymmetric standard model is extended to have right-handed neutrinos, the left-handed sleptons in the second and third generations are expected to have the LFV masses in the minimal supergravity scenario. In this article we study the LFV signals in the left-handed slepton production at $μ^+μ^-$ colliders and $\e^+\e^-$ linear colliders (LC's), $μ^+μ^-(\e^+\e^-)\toτμ+4jets + \E$ and $μ^+μ^-(\e^+\e^-)\toτμl+ 2jets+ \E$. The main ba…
We explore scenarios where the $R(D^{(*)})$ anomalies arise from semitauonic decays to a right-handed sterile neutrino. We perform an EFT study of all five simplified models capable of generating at tree-level the lowest dimension electroweak operators that give rise to this decay. We analyze their compatibility with current $R(D^{(*)})$ data and other relevant hadronic branching ratios, and show that one simplified model is excluded by this analysis. The remainder are compatible with collider constraints on the mediator semileptonic branching ratios, provided the mediator mass is of order TeV…
This talk gives a brief introduction to open questions in jet physics and QCD which come to the fore in the high-luminosity regime characterizing the upcoming phase of the Large Hadron Collider and future hadron colliders.
Supersymmetry relates neutrinos with their superpartners, sneutrinos. Unlike neutrinos, sneutrinos may decay visibly in colliders. We discuss how we could get information from neutrino Yukawa couplings in the NMSSM extended with right-handed neutrinos, if the right-handed sneutrinos are within the reach of the colliders.
Strong mixing between right-handed strange and beauty squarks is a possible solution to the CP violation discrepancy in $B\to ϕK_S$ decay as recently suggested by the Belle data. In this scenario, thanks to the strong mixing one of the strange-beauty squarks can be as light as 200 GeV, even though the generic supersymmetry scale is at TeV. In this work, we study the production of this light right-handed strange-beauty squark at hadronic colliders and discuss the detection in various decay scenarios. Detection prospect at the Tevatron Run II is good for the strange-beauty squark mass up to abou…
We point out that a study of event shapes at hadron colliders allows to explore novel aspects of QCD. These studies are today made easier by the development of a program which automates the resummation.
A compilation is given of the pair production cross sections for scalar and vector leptoquarks in the kinematic range of the hadron colliders Tevatron and LHC.
We discuss phenomenology of the radiative seesaw model in which spontaneous breaking of the U(1)$_{B-L}$ gauge symmetry at the TeV scale gives the common origin for masses of neutrinos and dark matter (Kanemura et al., 2012). In this model, the stability of dark matter is realized by the global U(1)$_{DM}$ symmetry which arises by the B$-$L charge assignment. Right-handed neutrinos obtain TeV scale Majorana masses at the tree level. Dirac masses of neutrinos are generated via one-loop diagrams. Consequently, tiny neutrino masses are generated at the two-loop level by the seesaw mechanism. This…
I discuss the impact of the the coherent parton radiation on semi-inclusive production of hadrons in deep inelastic scattering at lepton-proton colliders. Such radiation can be consistently described in the $b$-space resummation formalism, which was originally developed to improve theoretical description of production of hadrons at $e^+e^-$ colliders and electroweak vector bosons at hadron-hadron colliders. I present the detailed derivation of the resummed cross section and the energy flow at the next-to-leading order of perturbative QCD. The theoretical results are compared to the experimenta…
The theoretical status of Higgs boson and supersymmetric particle production at hadron colliders is reviewed with particular emphasis on recent results and open problems.
To provide context for discussions of experiments at future muon colliders, I survey what is known and what will be known about the top quark and the Higgs boson from experiments at hadron colliders.
We study the Standard Model effective field theory ($ν$SMEFT) extended with operators involving right-handed neutrinos, focussing on the regime where the right-handed neutrinos decay promptly on collider scales to a photon and a Standard Model neutrino. This scenario arises naturally for right-handed neutrinos with masses of the order $m_N \sim 0.1 \dots 10\, \text{GeV}$. We limit the relevant dimension-six operator coefficients using LEP and LHC searches with photons and missing energy in the final state as well as pion and tau decays. While bounds on new physics contributions are generally i…
Recently it has been shown that measurement of charge asymmetry of top pair production at LHC excludes any flavor violating $Z'$ vector gauge boson that could explain Tevatron forward-backward asymmetry (FBA). We consider the general form of a $Z'$ gauge boson including left-handed, right-handed vector and tensor couplings to examine FBA and charge asymmetry. To evaluate top pair asymmetries at Tevatron and LHC, we consider $B^0_q$ mixing constraints on flavor changing $Z'$ couplings and show that this model still explain forward-backward asymmetry at Tevatron and charge asymmetry can not excl…
The invisible signals of right-handed sneutrino decays originating from a Z' are analysed at the Large Hadron Collider. The possibility of accessing these events helps disentangling the B-L extension of Minimal Supersymmetric Standard Model from more popular scenarios of Supersymmetry. We assess the scope of the CERN machine in establishing the aforementioned signatures when accompanied by mono-jet, single-photon or Z-radiation probes through sophisticated signal-to-background simulations carried out in presence of parton shower, hadronisation as well as detector effects. We find substantial s…
We examine the effects of magnetic moments of right-handed neutrinos, whose masses are set at around TeV scale, then it is plausible to have a large enhancement for the production cross section of TeV scale right-handed neutrinos though the Drell-Yan process, e^+ e^- to gamma, Z* to N_i N_j, which is within the reach of the future linear collider (ILC).
The extension of Majorana neutrino mass mechanism of the neutrinoless double-beta decay ($0νββ$) with the inclusion of right-handed leptonic and hadronic currents is revisited. While only the exchange of light neutrinos is assumed, the $s_{1/2}$ and $p_{1/2}$-states of emitted electrons as well as recoil corrections to the nucleon currents are taken into account. Within the standard approximations the decay rate is factorized into a sum of products of kinematical phase-space factors, nuclear matrix elements and the fundamental parameters that characterize the lepton number violation. Unlike in…
This writeup gives an introduction to the theoretical understanding that lies behind automated resummation. It then discusses its applications to hadron-collider event shapes.
I survey the characteristics of hadron colliders as tools to investigate top-quark physics and to explore the 1-TeV scale of electroweak symmetry breaking.
It can be expected from the result for the atmospheric neutrino by the SUPERKAMIOKANDE and the CHOOZ result that the the lepton-flavor violating (LFV) interaction between the second and third generations exits at the high energy scale. This leads to a non-vanishing LFV left-handed slepton mass between the second and third generations, induced by the radiative correction, in the minimal supergravity scenario. In this article, assuming that the supersymmetric standard model with the right-handed neutrinos explains the atmospheric neutrino result, we show that the reach of the LFV slepton product…
We report the calculation of next-to-next-to-leading order (NNLO) QCD corrections in the purely gluonic channel to dijet production and related observables at hadron colliders. Our result represents the first NNLO calculation of a massless jet observable at hadron colliders, and opens the path towards precision QCD phenomenology with the LHC.
We study the flavor-changing decay $h\to τμ$ with $τ=τ^-+τ^+$ and $μ=μ^-+μ^+$ of a Higgs boson at future hadron colliders, namely: a) High Luminosity Large Hadron Collider, b) High Energy Large Hadron Collider and c) Future hadron-hadron Circular Collider. The theoretical framework adopted is the Two-Higgs-Doublet Model type III. The free model parameters involved in the calculation are constrained through Higgs boson data, Lepton Flavor Violating processes and the muon anomalous magnetic dipole moment; later they are used to analyze the branching ratio of the decay $h\toτμ$ and to evaluate th…
We discuss theoretical aspects of parton distribution functions for very high energy scattering in relation with upcoming measurements in DIS and hadron-hadron collisions.
We study some New Physics effects on the hadronic decays of the Top quark, like t-> b bbar c, and on a forward-backward-like CP even asymmetry A_t constructed in such a way that it is zero in the SM. We find that an anomalous right-handed contribution of the effective tbW vertex may induce an asymmetry A_t of the order of 20 %. A light W' boson with pure right handed couplings tdW' may induce an asymmetry A_t of the same order of magnitude.
The current theoretical understanding of anomalous gauge boson couplings is reviewed, and the direct measurement of these couplings in present and future hadron collider experiments is briefly discussed.
Extending the standard model with three right-handed neutrinos ($N_k$) and a second Higgs doublet ($η$), odd under the discrete parity symmetry $Z_2$, Majorana neutrino masses can be generated at 1-loop order. In the resulting model, the lightest stable particle, either a boson or a fermion, might be a dark matter candidate. Here we assume a specific mass spectrum ($M_1\ll M_2 < M_3 < m_η$) and derive its consequences for dark matter and collider phenomenology. We show that (i) the lightest right-handed neutrino is a warm dark matter particle that can give a $\sim$10% contribution to the dark …
In many models incorporating the type-I seesaw mechanism, the right-handed neutrino ($N$) couples to heavy vector/scalar bosons and thereby has resonant pair production. It barely receives attention thus far, however, it may provide the best avenue to probe TeV scale $N$ without requiring anomalously large mixing between $N$ and the active neutrino $ν_L$. In this paper we explore the discovery prospects of (mainly heavy) $N$ pair production at the 14 TeV LHC and future 100 TeV $pp$ collider, based on the three signatures: 1) trilepton from $ N(\rightarrow \ell W_\ell)N(\rightarrow \ell W_h)$ w…
In a class of neutrino mass models with a lepton flavor violation (LFV) Yukawa interaction term that involves a heavy right handed neutrino, a charged scalar and a charged lepton, we investigate at the ILC@500 GeV the possibility of observing news physics. These models can address neutrino mass and dark matter without being in conflict with different LFV constraints. By imposing DM relic density and LFV constraints, we recast the analysis done by L3 collaboration at LEP-II of monophoton searches on our space parameter and look for new physics in such channels like monophoton and $S S(γ)$, wher…
We review the recent theoretical progress in single-top physics at hadron colliders. Apart from single-top production within the Standard Model we treat certain aspects of single-top production in beyond Standard Model scenarios.
We present compact analytic expressions for all one-loop helicity amplitudes contributing to ttbar production at hadron colliders. Using recently developed generalised unitarity methods and a traditional Feynman based approach we produce a fast and flexible implementation.
The effects of possible right-handed weak hadronic currents in rare exclusive semileptonic decays B -> (K, K*) nu bar{nu} are investigated using a lattice-constrained dispersion quark model for the calculation of the relevant mesonic form factors. The results obtained for the branching ratios and the missing energy spectra are presented and the sensitivity of various observables to long-distance physics is investigated. It is shown that the asymmetry of transversely polarized K*(T) mesons as well as the K / K*(T) production ratio are only slightly sensitive to long-distance contributions and m…
We investigate the discovery potential of Kaluza-Klein gluons as a dijet resonance at hadron colliders with different center-of-mass energies, from 14 TeV to 33 TeV to 100 TeV. We also present the current bounds from dijet searches at UA2, Tevatron, and LHC.
We present here the results for Higgs and Supersymmetry prospective searches at the Large Hadron Collider. We show that for one year at high luminosity, Standard Model and MSSM Higgs should be observed within the theoretically expected mass range. MSUGRA and restricted phenomenological MSSM searches lead to discovery of up to 2.5 TeV squarks and gluinos.