In this talk I summarize the physics case of the International Linear Collider (ILC) focusing on its potential towards discovery, discrimation or disentanglement of new physics beyond the Standard Model (BSM).
The LHC experiments have searched for and excluded many proposed Beyond the Standard Model (BSM) theories. However, there are many scenarios where LHC has little or no sensitivity. Electron-positron colliders offers a different avenue for searches for such phenomena.In this talk, we will review the expectations for searches for number of BSM models at the International Linear Collider (ILC). We will discuss new Higgs-like scalars, indirect BSM via Standard Model Effective Field Theory (SMEFT) fits, mono-photons, and SUSY in strongly or moderately compressed models.
The particle discovered in the Higgs boson searches at the LHC with a mass of about 125 GeV is compatible within the present uncertainties with the Higgs boson predicted in the Standard Model (SM), but it could also be identified with one of the neutral Higgs bosons in a variety of Beyond the SM (BSM) theories with an extended Higgs sector. The possibility that an additional Higgs boson (or even more than one) could be lighter than the state that has been detected at 125 GeV occurs generically in many BSM models and has some support from slight excesses that were observed above the background …
Although the LHC experiments have searched for and excluded many proposed new particles up to masses close to 1 TeV, there are many scenarios that are difficult to address at a hadron collider. This talk will review a number of these scenarios and present the expectations for searches at an electron-positron collider such as the International Linear Collider. The cases discussed include the light Higgsino, the \stau~ slepton in the coannihilation region relevant to dark matter, as well as other BSM signatures. The studies are based on the ILD concept at the ILC.
In this paper I review the calculations (and partially simulations and theoretical studies) that have been made and published during the last two to three years focusing on the electroweak symmetry breaking sector and the Higgs boson(s) within the Standard Model and models beyond the Standard Model (BSM) at or relevant for either the International Linear Collider (ILC) or the Compact Linear Collider (CLIC), commonly abbreviated as Linear Collider (LC).
We review the ILC capabilities to explore the electroweak (EW) sector of the SM at high precision and the prospects of unveiling signals of BSM physics, either through the presence of new particles in higher-order corrections or via direct production of extra EW gauge bosons. This includes electroweak precision observables, global fits to the SM Higgs boson mass as well as triple and quartic gauge boson couplings.
The public collider phenomenology computing tool CheckMATE (Check Models at Terascale Energies) was originally designed to allow theorists to quickly test their favourite BSM models against various existing LHC analyses performed by ATLAS and CMS. It offers an automatised chain of Monte Carlo event generation, detector simulation, event analysis and statistical evaluation so that it can automatically determine whether a given parameter point of a BSM model is excluded or not. Currently, it contains more than 50 individual ATLAS or CMS analyses whose several hundred signal regions target variou…
One of the most-studied signals for physics beyond the standard model in the production of gauge bosons in electron-positron collisions is that due to the anomalous triple gauge boson couplings in the $Z γ$ final state. In this work, we study the implications of this at the ILC with polarized beams for signals that go beyond traditional anomalous triple neutral gauge boson couplings. Here we report a dimension-8 CP-conserving $Z γZ$ vertex that has not found mention in the literature. We carry out a systematic study of the anomalous couplings in general terms and arrive at a classification. We…
The origin of neutrino mass is a big unsolved problem of the Standard Model (SM) that motivate us to consider beyond the SM (BSM) scenarios where SM-singlet right-handed neutrinos (RHNs) are introduced to explain the origin of the light neutrino masses through the seesaw mechanism. There is a variety of ways which could lead us to this goal and one of them is a general U$(1)$ extension of the SM. In this scenario, three SM-singlet RHNs are introduced to cancel the gauge and mixed gauge gravity anomalies. After anomaly cancellation, we notice that the left- and right-handed charged fermions are…
We present a physical parameterization of the leading effects beyond the SM (BSM), that give us, at present, the best way to constrain heavy new-physics at low-energies. We call these effects that constrain all possible interactions at the dimension 6 level, BSM Primary effects; there are 8 primaries related to Higgs physics, 3 related to Triple Gauge Couplings and 7 related to Z- pole measurements at LEP. Starting from these experimentally measurable deformations (and not operators), we construct the dimension 6 Lagrangian in a bottom up way. We, thus, show that other BSM effects are not inde…
Physics at the ILC is reviewed focusing mostly on Higgs physics. It is emphasized that at the ILC it is possible to measure the $hZZ$ coupling totally model independently, which in turn allows model-independent normalization of various branching ratio measurements and consequently the absolute measurements of corresponding couplings. Combining them with the measurements of the top Yukawa coupling and the Higgs self-coupling at higher energies, the full ILC program is shown to allow a precision test of the mass-coupling relation.
In the Standard Model (SM) of particle physics, the branching ratio for Higgs boson decays to a final state which is invisible to collider detectors, $H \rightarrow ZZ^{\star} \rightarrow ν\barν ν\barν$, is order 0.10%. In theories beyond the SM (BSM), this branching ratio can be enhanced by decays to undiscovered particles like dark matter (DM). At the Large Hadron Collider (LHC), the current best upper limit on the branching ratio of invisible Higgs boson decays is 11% at 95% confidence level. We investigate the expected sensitivity to invisible Higgs decays with the Silicon Detector (SiD) a…
We describe recent work on the physics of the Higgs boson at future muon colliders. Starting from the low energy muon collider at the Higgs boson pole we extend our discussion to the multi-TeV muon collider and outline the physics case for such machines about the properties of the Higgs boson and physics beyond the Standard Model that can be possibly discovered.
This topical group focuses on searches for signals from physics Beyond the Standard Model (BSM), both from a theoretical and experimental perspective, including neutrino-related BSM and searches for BSM in other sectors using neutrino facilities.
The International Linear Collider (ILC) and the Compact Linear Collider (CLIC) are the two options for a future high-energy, high-luminosity linear electron-positron collider. Both are expected to be built in stages, optimised for their physics potential. The main goals are the precision measurements of Higgs-boson and top-quark properties as well as direct and indirect searches for new physics Beyond Standard Model. In my talk I will review some of the latest results from both ILC and CLIC demonstrating their physics potential, pointing to similarities and complementarity of both projects.
With the advent of a new generation of neutrino experiments which leverage high-intensity neutrino beams for precision measurements, it is timely to explore physics topics beyond the standard neutrino-related physics. Given that the realm of beyond the standard model (BSM) physics has been mostly sought at high-energy regimes at colliders, such as the LHC at CERN, the exploration of BSM physics in neutrino experiments will enable complementary measurements at the energy regimes that balance that of the LHC. This is in concert with new ideas for high-intensity beams for fixed target and beam-du…
We reiterate that there is significant complementarity between low-energy experiments and high-energy colliders in exploring new physics associated with neutrino properties and their mass generation mechanisms. Signals of the new physics in the two energy regimes may be correlated with each other from the same underlying dynamics. We demonstrate the complementary nature by presenting the physics reaches for the Seesaw models of Type I, II and III, and for general neutrino interactions in an effective field theory framework, and in a $Z'$ model.
Semileptonic Flavor Changing Neutral Current decays of charmed hadrons uniquely probe the up-sector of the Standard Model. Clean null test observables, such as CP-asymmetries, lepton-universality ratios, missing energy modes, lepton flavor violating modes and angular observables can be studied in a variety of charmed meson and baryon modes. An overview of null test opportunities with rare charm decays is presented and similarities and complementarities of different modes are worked out.
We describe DSiD, a fast simulation Delphes detector for the International Linear Collider (ILC) based on the full simulation performance of the SiD detector. SiD is one of two detectors described in the ILC Technical Design Report (TDR). The tracking efficiency, tracking momentum resolution, electromagnetic and hadronic calorimeter energy resolution, particle identification and flavor tagging efficiencies are taken from the Detailed Baseline Design (DBD) study as described in ILC TDR Volume 4: Detectors. In a cross-check study with $4 \times 10^6$ $e^+ e^- \rightarrow b \bar{b}$ events genera…
Although the LHC experiments have searched for and excluded many proposed new particles up to masses close to 1 TeV, there are many scenarios that are difficult to address at a hadron collider. This talk will review a number of these scenarios and present the expectations for searches at an electron-positron collider such as the International Linear Collider. The cases discussed include the light Higgsino, the \stau~ slepton in the coannihilation region relevant to dark matter, as well as other SUSY signatures. he studies are based on the ILD concept at the ILC.
The ILC Technical Design Report documents the design of a 500 GeV linear collider, but does not specify the center-of-mass energy steps of operation for the collider. The ILC Parameters Joint Working Group has studied possible running scenarios, including a realistic estimate of the real time accumulation of integrated luminosity based on ramp-up and upgrade processes, and considered the evolution of the physics outcomes. These physics goals include Higgs precision measurements, top quark measurements and searches for new physics. We present an "optimized" operating scenario and the anticipate…
The International Linear Collider (ILC) has recently proven its technical maturity with the publication of a Technical Design Report, and there is a strong interest in Japan to host such a machine. We summarize key aspects of the Beyond the Standard Model physics case for the ILC in this contribution to the US High Energy Physics strategy process. On top of the strong guaranteed physics case in the detailed exploration of the recently discovered Higgs boson, the top quark and electroweak precision measurements, the ILC will offer unique opportunities which are complementary to the LHC program …
I provide an overview of the connections between flavor violating observables in the K and B meson systems beyond the Standard Model (BSM). Model independent correlations, both in and beyond the MFV framework, as well as results obtained in specific models are discussed.
We present a study of the sensitivity of an International Linear Collider (ILC) to electroweak parameters in the absence of a light Higgs boson. In particular, we consider those parameters that have been inaccessible at previous colliders, quartic gauge couplings. Within a generic effective-field theory context we analyze all processes that contain quasi-elastic weak-boson scattering, using complete six-fermion matrix elements in unweighted event samples, fast simulation of the ILC detector, and a multidimensional parameter fit of the set of anomalous couplings. The analysis does not rely on s…
Although the LHC experiments have searched for and excluded many proposed new particles up to masses close to 1 TeV, there are many scenarios that are difficult to address at a hadron collider. This talk will review a number of these scenarios and present the expectations for searches at an electron-positron collider such as the International Linear Collider. The cases discussed include the light Higgsino, the stau lepton in the coannihilation region relevant to dark matter, and heavy vector bosons coupling to the s-channel in e$^+$e$^-$ annihilation. The studies are based on the ILD concept a…
In this work we study the production of two Higgs bosons at the two planned electron positron colliders with energies at the TeV domain, CLIC and ILC, within the context of Effective Field Theories (EFTs) to describe beyond the Standard Model Higgs Physics. We focus first on the case of the Higgs Effective Field Theory (HEFT) and next we compare with the case of the Standard Model Effective Field Theory (SMEFT). The predictions for double Higgs production in both EFTs are first presented for the most relevant subprocess participating in the total process of our interest, $e^+e^- \to HH ν\bar ν…
Discoveries come through exclusions, confirmations or revolutionary findings with respect to a theory canon populated by the Standard Model (SM) and beyond the SM (BSM) theories. Guaranteed discoveries are accomplished only through pursuit of BSM exclusion/confirmation, and thus require investment in the continual formation and analysis of a vibrant theory canon combined with investment in experiment with demonstrated capacity to make BSM exclusions/confirmations. Risks develop when steering away from BSM-oriented work toward its methodological rival, "signalism," which seeks to realize SM fal…
The plan for the International Linear Collider (ILC) is now being prepared as a staged design, with the first stage of 2 ${\rm ab^{-1}}$ at 250GeV and later stages achieving the full project specifications with 4 ${\rm ab^{-1}}$ at 500 GeV. The talk presents the capabilities for precision Higgs boson measurements at 250 GeV. It is shown that the 250 GeV stage of the ILC will already provide many compelling results in Higgs physics, with new measurements unavailable at the Large Hadron Collider, model-independent determinations of key parameters, and possible discrimination of a variety of scen…
Rare $\vert Δc \vert=\vert Δu \vert=1$ processes uniquely probe flavor in the Standard Model and beyond from the up-type quark sector. Opportunities to search for BSM physics in charm arise from the severe GIM suppression which kills SM contributions to leptonic axial-vector contributions and suppresses CP violation. Semileptonic decays of charmed hadrons offer a variety of clean null test observables, featuring new physics effects which are even enhanced by resonance contributions. In particular, angular observables in three- and self-analyzing four-body baryon decays, such as $Λ_c\to p \ell^…
In a class of new physics models, new physics sector is completely or partly hidden, namely, singlet under the Standard Model (SM) gauge group. Hidden fields included in such new physics models communicate with the Standard Model sector through higher dimensional operators. If a cutoff lies in the TeV range, such hidden fields can be produced at future colliders. We consider a scalar filed as an example of the hidden fields. Collider phenomenology on this hidden scalar is similar to that of the SM Higgs boson, but there are several features quite different from those of the Higgs boson. We inv…
The plan for the International Linear Collider is now being prepared as a staged design, with the first stage at 250 GeV and later stages achieving the full project specifications with 4 ab-1 at 500 GeV. This talk will present the capabilities for precision Higgs boson measurements at 250 GeV and their relation to the full ILC program. It will show that the 250 GeV stage of ILC will already provide many compelling results in Higgs physics, with new measurements not available at LHC, model-independent determinations of key parameters, and tests for and possible discrimination of a variety of sc…
We investigate the possibility of the identification of TeV physics models including WIMP dark matter at the International Linear Collider. Many TeV physics models contain a WIMP dark matter (chi^0) and charged new particle (chi^{pm}) which interacts with the WIMP dark matter via the vertex chi^{pm} chi^0 W^{mp}. Through Monte Carlo simulations, we study the process, e^+e^- to chi^+ chi^- to chi^0 chi^0 W^+ W^-, because the signal contains the fruitful information of the model. We show that, in particular, the distribution of the chi^{pm} production angle is the powerful probe in the TeV physi…
Precise measurements of electroweak processes at the International Linear Collider (ILC) will provide unique opportunities to explore new physics beyond the Standard Model. Fermion pair productions are sensitive to a new contact interaction or a new heavy gauge boson by comparing cross section and angular distribution with expectations of the new physics models. In this proceedings we report a simulation study of fermion pair productions at a center-of-mass energy of 250 GeV, with a focus on lepton pairs, to demonstrate the potential of the first phase of the ILC.
We study capability of the ILC beam dump experiment to search for new physics, comparing the performance of the electron and positron beam dumps. The dark photon, axion-like particles, and light scalar bosons are considered as new physics scenarios, where all the important production mechanisms are included: electron-positron pair-annihilation, Primakoff process, and bremsstrahlung productions. We find that the ILC beam dump experiment has higher sensitivity than past beam dump experiments, with the positron beam dump having slightly better performance for new physics particles which are produ…
Proposals of measuring the off-shell Higgs contributions and first measurements at the LHC have electrified the Higgs phenomenology community for two reasons: Firstly, probing interactions at high invariant masses and momentum transfers is intrinsically sensitive to new physics beyond the Standard Model, irrespective of a resonant or non-resonant character of a particular BSM scenario. Secondly, under specific assumptions a class of models exists for which the off-shell coupling measurement together with a measurement of the on-shell signal strength can be re-interpreted in terms of a bound on…
Supersymmetry (SUSY) with bilinearly broken R parity (bRPV) offers an attractive possibility to explain the origin of neutrino masses and mixings. In such scenarios, the study of neutralino decays at colliders gives access to neutrino sector parameters. The ILC offers a very clean environment to study the neutralino properties as well as its subsequent decays, which typically involve a $W$ or $Z$ boson and a lepton. This study is based on ILC beam parameters according to the Technical Design Report for a center of mass energy of $500\,\mathrm{GeV}$. A full detector simulation of the Internatio…
Using the predictive power of the effective field theory approach, we present a physical parametrization of the leading effects beyond the SM (BSM), that give us at present the best way to constrain heavy new-physics at low-energies. We show that other BSM effects are not independent from these ones, and we provide the explicit correlations. This information is useful to know where to primarily look for new physics in future experiments, and to know how this new physics is related to previous measurements, most importantly in electroweak-symmetry breaking processes or Higgs physics.
Many theories, from Supersymmetry to models of Strong Electroweak Symmetry Breaking, look at the production of four top quarks as an interesting channel to evidentiate signals of new physics beyond the Standard Model. The production of four-top final states requires large partonic energies, above the 4mt threshold, that are available at the CERN Large Hadron Collider and will become more and more accessible with increasing energy and luminosity of the proton beams. A good theoretical control on the Standard Model background is a fundamental prerequisite for a correct interpretation of the poss…
A modified narrow-width approximation that allows for O(Gamma/M)-accurate predictions for resonant particle decay with similar intermediate masses is proposed and applied to MSSM processes to demonstrate its importance for searches for particle physics beyond the Standard Model.
In this talk, I shall first discuss the standard model Higgs mechanism and then highlight some of its deficiencies making a case for the need to go beyond the standard model (BSM). The BSM tour will be guided by symmetry arguments. I shall pick up four specific BSM scenarios, namely, supersymmetry, Little Higgs, Gauge-Higgs unification, and the Higgsless approach. The discussion will be confined mainly on their electroweak symmetry breaking aspects.
This paper intends to collect available data on searches for scalar resonances at LHC. It is suggested that, in the absence of SUSY, the most compelling picture is the composite framework, with the idea that the lightest particles are composite scalars of the pseudo-Nambu-Goldstone type, emerging from a broken symmetry at a higher scale, the h(125) boson being one of them. Searches in two-photons, Z-photon, ZZ into 4 leptons, top, h and W pairs are reviewed. A recent search based on lepton tagging from a spectator W/Z is also discussed. Aside from the already well-known scalar observed by CMS …
We first outline the Standard Model (SM) of particle physics, particle production and decay, and the expected signal and background at a Higgs factory like the International Linear Collider (ILC). We then introduce high energy colliders and collider detectors, and briefly detail the ILC and the Silicon Detector (SiD), one of the two detectors proposed for the ILC. Next we review the available software tools for ILC event generation, SiD detector simulation, and event reconstruction. Finally we suggest open avenues in research for detector optimization and physics analysis. The pedagogical leve…
Electron-proton ($e^-p$) colliders are an ideal laboratory to study common features of electron and quarks with production via electroweak bosons, leptoquarks, multi-jet final states and very forward physics, due to their impressive pseudorapidity coverage. In addition to these physics cases, there exist a broad Beyond the Standard Model (BSM) program aimed at exploring the capabilities of the LHeC [1] and FCC-he [2] for several New Physics scenarios. Although their centre-of-mass energy is down with respect to a $pp$ collider by a factor of $\sqrt{E_p/E_e} \sim 10~(30)$ for the LHeC (FCC-he),…
Some aspects of electroweak physics at the International Linear Collider (ILC) are reviewed. The importance of precision measurements in the Higgs sector and in top-quark physics is emphasized, and the physics potential of the GigaZ option of the ILC is discussed. It is shown in particular that even in a scenario where the states of new physics are so heavy that they would be outside of the reach of the LHC and the first phase of the ILC, the GigaZ precision on the effective weak mixing angle may nevertheless allow the detection of quantum effects of new physics.
Effective Field Theories (EFTs) capture effects from heavy dynamics at low energy and represent an essential ingredient in the context of Standard Model (SM) precision tests. This document gathers a number of relevant scenarios for heavy physics beyond the SM and presents explicit expressions for the Wilson coefficients in their low-energy EFT. It includes i) weakly coupled scenarios in which one or a few particles of different spins and quantum numbers interact linearly with the SM and generate EFT effects at tree-level, ii) scenarios where heavy particles interact quadratically whereupon the…
Many Beyond-Standard Model physics signatures are enhanced in high-energy neutrino interactions. To explore these signatures, ultra-large Cherenkov detectors such as IceCube exploit event samples with charged current muon neutrino interactions > 1 TeV. Most of these interactions occur below the detector volume, and produce muons that enter the detector. However, the large spacing between detectors leads to inefficiency for measuring muons with energies below or near the critical energy of 400 GeV. In response, IceCube has built a densely instrumented region within the larger detector. This pro…
This article reviews the physics case for the ILC. Baseline running at 500 GeV as well as possible upgrades and options are discussed. The opportunities on Standard Model physics, Higgs physics, Supersymmetry and alternative theories beyond the Standard Model are described.
Charged Higgs boson can exist in many physics beyond the standard models (BSM) and it is the obvious BSM signal. We briefly describe why the 125GeV scalar discovered at the LHC must have (heavy) companion: the charged Higgs boson, in a new paradigm. We then focus on the charged Higgs phenomenology, especially on how to measure $\tanβ$ precisely utilizing the top quark polarization information.
Run 2 of the LHC offers some beautiful prospects for new physics, including flavour physics as well as more detailed studies of the Higgs boson and searches for new physics beyond the Standard Model (BSM). One of the possibilities for BSM physics is supersymmetry, and flavour physics plays various important rôles in constraining supersymmetric models.
Now Standard $Λ$CDM cosmology is based on physics Beyond the Standard Model (BSM), which in turn needs cosmological probes for its study. This vicious circle of problems can be resolved by methods of cosmoparticle physics, in which cosmological messengers of new physics provide sensitive model dependent probes for BSM physics. Such messengers, which are inevitably present in any BSM basis for now Standard cosmology, lead to deviations from the Standard cosmological paradigm. We give brief review of some possible cosmological features and messengers of BSM physics, which include balancing of ba…
In contrast with $B^0-\bar B^0$, $B_s-\bar B_s$ mixing where the standard model (SM) contributions overwhelm that of new physics beyond standard model (BSM), a measured relatively large $D^0-\bar D^0$ mixing where the SM contribution is negligible, definitely implies the existence of new physics BSM. It is natural to consider that the rare decays of D meson might be more sensitive to new physics, and the rare decay $D^0\to μ^+μ^-$ could be an ideal area to search for new physics because it is a flavor changing process. In this work we look for a trace of new physics BSM in the leptonic decays …
A high-energy $e^+e^-$ Linear Collider has been considered since a long time as an important complement to the LHC. Unprecedented precision measurements as well as the exploration of so far untouched phase space for direct production of new particles will provide unique information to advance the limits of our understanding of our universe. Within this project, the physics prospects of such a collider as well as their interplay with design of the accelerator and the detectors have been investigated in a quantitative way. This kind of study required a close collaboration between theory and expe…
The LHC has collided protons on protons at center-of-mass energies of 7 and 8 TeV between 2010-2012, referred to as the Run I period. We review the current status of searches for new physics beyond the Standard Model at the end of Run I by the ATLAS and CMS experiments, limited to the 8 TeV search results published or submitted for publication as of the end of February 2014. We discuss some of the implications of these searches on the existence of TeV scale new physics, with a special focus on two open questions: the hierarchy problem, and the nature of dark matter. Finally, we give an outlook…
We describe ColliderBit, a new code for the calculation of high energy collider observables in theories of physics beyond the Standard Model (BSM). ColliderBit features a generic interface to BSM models, a unique parallelised Monte Carlo event generation scheme suitable for large-scale supercomputer applications, and a number of LHC analyses, covering a reasonable range of the BSM signatures currently sought by ATLAS and CMS. ColliderBit also calculates likelihoods for Higgs sector observables, and LEP searches for BSM particles. These features are provided by a combination of new code unique …
The prospects for electroweak precision physics at the LHC and the ILC are reviewed. This includes projections for measurements of the effective Z pole weak mixing angle, sin^2 theta_W (eff.), as well as top quark, W boson, and Higgs scalar properties. The upcoming years may also see very precise determinations of sin^2 theta_W (eff.) from lower energies.
We explore beyond Standard Model (bSM) physics signatures in the $l+jets$ channel of $t\overline{t}$ pair production process at the Tevatron and the LHC. We study the effects of bSM physics scenarios on the top quark polarization and on the kinematics of the decay leptons. To this end, we construct asymmetries using the lepton energy and angular distributions. Further, we find their correlations with the top polarization, net charge asymmetry and top forward backward asymmetry. We show that used together, these observables can help discriminate effectively between SM and different bSM scenario…