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Anomalous $WW\gamma$ couplings with beam polarization at the Compact Linear Collider
http://ilcdoc.linearcollider.org/record/61870
We study the anomalous $WW\gamma$ couplings at the Compact Linear Collider through the processes $e^{+}e^{-}\to W^+W^-$, $e^{-}e^{+} \to e^{-} \gamma^{*} e^{+} \to e^{+} \nu_{e} W^-$ and $e^{-}e^{+}\to e^{-} \gamma^{*} \gamma^{*} e^{+} \to e^{-} W^+ W^- e^{+} $ $ (\gamma^{*}$ is the Weizsacker-Williams photon). We give the 95\% confidence level limits for unpolarized and polarized electron (positron) beam on the anomalous couplings for various values of the integrated luminosities and center-of-mass energies. We show that the obtained limits on the anomalous couplings through these processes can highly improve the current experimental limits. In addition, our limits with beam polarization are approximately two times better than the unpolarized case.ArÄ±, VWed, 01 Jul 2015 22:36:46 GMThttp://ilcdoc.linearcollider.org/record/618702015Discriminating between SUSY and Non-SUSY Higgs Sectors through the Ratio $H \to b \bar b / H \to \tau \bar \tau$ with a Higgs boson of 125 GeV
http://ilcdoc.linearcollider.org/record/61868
It is still an open question whether the new scalar particle discovered at the LHC with a mass of 125 GeV is the SM Higgs boson or it belongs to models of new physics with an extended Higgs sector, as the MSSM or 2HDM. The ratio of branching fractions $R$ = BR($H \to b \bar b$)/BR($H \to \tau \bar \tau$) of Higgs boson decays is a powerful tool in order to distinguish the MSSM Higgs sector from the SM or non-supersymmetric 2HDM. This ratio receives large renormalization-scheme independent radiative corrections in supersymmetric models at large $\tan\beta$, which are insensitive to the SUSY mass scale ($M_\text{SUSY}$) and absent in the SM or 2HDM. Making use of the current LHC data and the upcoming new results on Higgs couplings to be reported by ATLAS and CMS collaborations and in a future linear collider, we develop a detailed and updated study of this ratio $R$ which improves previous analyses and sets the level of accuracy needed to discriminate between models.Arganda, ETue, 30 Jun 2015 22:35:04 GMThttp://ilcdoc.linearcollider.org/record/618682015Extending the Matrix Element Method beyond the Born approximation: Calculating event weights at next-to-leading order accuracy
http://ilcdoc.linearcollider.org/record/61867
In this article we illustrate how event weights for jet events can be calculated efficiently at next-to-leading order (NLO) accuracy in QCD. This is a crucial prerequisite for the application of the Matrix Element Method in NLO. We modify the recombination procedure used in jet algorithms, to allow a factorisation of the phase space for the real corrections into resolved and unresolved regions. Using an appropriate infrared regulator the latter can be integrated numerically. As illustration, we reproduce differential distributions at NLO for two sample processes. As further application and proof of concept, we apply the Matrix Element Method in NLO accuracy to the mass determination of top quarks produced in e+e- annihilation. This analysis is relevant for a future Linear Collider. We observe a significant shift in the extracted mass depending on whether the Matrix Element Method is used in leading or next-to-leading order.Martini, TillTue, 30 Jun 2015 22:35:03 GMThttp://ilcdoc.linearcollider.org/record/618672015LCFIPlus: A Framework for Jet Analysis in Linear Collider Studies
http://ilcdoc.linearcollider.org/record/61866
We report on the progress in flavor identification tools developed for a future $e^+e^-$ linear collider such as the International Linear Collider (ILC) and Compact Linear Collider (CLIC). Building on the work carried out by the LCFIVertex collaboration, we employ new strategies in vertex finding and jet finding, and introduce new discriminating variables for jet flavor identification. We present the performance of the new algorithms in the conditions simulated using a detector concept designed for the ILC. The algorithms have been successfully used in ILC physics simulation studies, such as those presented in the ILC Technical Design Report.Suehara, TaikanTue, 30 Jun 2015 22:35:03 GMThttp://ilcdoc.linearcollider.org/record/618662015Gravitational mass of relativistic matter and antimatter
http://ilcdoc.linearcollider.org/record/61856
The universality of free fall, the weak equivalence principle (WEP), is a cornerstone of the general theory of relativity, the most precise theory of gravity confirmed in all experiments up to date. The WEP states the equivalence of the inertial, $m$, and gravitational, $m_g$, masses and was tested in numerous occasions with normal matter at relatively low energies. However, there is no proof for the matter and antimatter at high energies. For the antimatter the situation is even less clear -- current direct observations of trapped antihydrogen suggest the limits $-65 < m_g / m < 110$ not excluding the so-called antigravity phenomenon, i.e. repulsion of the antimatter by Earth. Here we demonstrate an indirect bound $0.96 < m_g/m < 1.04$ on the gravitational mass of relativistic electrons and positrons coming from the absence of the vacuum Cherenkov radiation at the Large Electron-Positron Collider (LEP) and stability of photons at the Tevatron collider in presence of the annual variations of the solar gravitational potential. Our result clearly rules out the speculated antigravity. By considering the absolute potential of the Local Supercluster (LS), we also predict the bounds $1 - 4\times 10^{-7} < m_g/m < 1 + 2\times 10^{-7}$ for an electron and positron. Finally, we comment on a possibility of performing complementary tests at the future International Linear Collider (ILC) and Compact Linear Collider (CLIC).Kalaydzhyan, TigranMon, 29 Jun 2015 22:33:20 GMThttp://ilcdoc.linearcollider.org/record/618562015$Z'$ resonance and associated $Zh$ production at future Higgs boson factory: ILC and CLIC
http://ilcdoc.linearcollider.org/record/61853
We study the prospects of the B-L model with an additional $Z'$ boson to be a Higgs boson factory at high-energy and high-luminosity linear electron positron colliders, such as the ILC and CLIC, through the Higgs-strahlung process $e^{+}e^{-}\rightarrow (Z, Z') \to Zh$, including both the resonant and non-resonant effects. We evaluate the total cross section of $Zh$ and we calculate the total number of events for integrated luminosities of 500-2000\hspace{0.8mm}$fb^{-1}$ and center of mass energies between 500 and 3000\hspace{0.8mm}$GeV$. We find that the total number of expected $Zh$ events can reach $10^6$, which is a very optimistic scenario and it would be possible to perform precision measurements for both the $Z'$ and Higgs boson in future high-energy $e^+e^-$ colliders experiments.Gutierrez-Rodriguez, AFri, 26 Jun 2015 22:28:20 GMThttp://ilcdoc.linearcollider.org/record/618532015Freeze-In Dark Matter with Displaced Signatures at Colliders
http://ilcdoc.linearcollider.org/record/61852
Dark matter, $X$, may be generated by new physics at the TeV scale during an early matter-dominated (MD) era that ends at temperature $T_R \ll {\rm TeV}$. Compared to the conventional radiation-dominated (RD) results, yields from both Freeze-Out and Freeze-In processes are greatly suppressed by dilution from entropy production, making Freeze-Out less plausible while allowing successful Freeze-In with a much larger coupling strength. Freeze-In is typically dominated by the decay of a particle $B$ of the thermal bath, $B \rightarrow X$. For a large fraction of the relevant cosmological parameter space, the decay rate required to produce the observed dark matter abundance leads to displaced signals at LHC and future colliders, for any $m_X$ in the range ${\rm keV} < m_X < m_B$ and for values of $m_B$ accessible to these colliders. This result applies whether the early MD era arises after conventional inflation, when $T_R$ is the usual reheat temperature, or is a generic MD era with an alternative origin. In the former case, if $m_X$ is sufficiently large to be measured from kinematics, the reheat temperature $T_R$ can be extracted. Our result is independent of the particular particle physics implementation of $B \rightarrow X$, and can occur via any operator of dimension less than 8 (4) for a post-inflation (general MD) cosmology. An interesting example is provided by DFS axion theories with TeV-scale supersymmetry and axino dark matter of mass GeV to TeV, which is typically overproduced in a conventional RD cosmology. If $B$ is the higgsino, $\tilde h$, Higgs, W and Z particles appear at the displaced decays, $\tilde h \rightarrow h \tilde a, Z \tilde a$ and $\tilde h^\pm \rightarrow W^\pm \tilde a$. The scale of axion physics, $f$, is predicted to be in the range $(3\times10^8 - 10^{12})$ GeV and, over much of this range, can be extracted from the decay length.Co, Raymond TFri, 26 Jun 2015 22:28:20 GMThttp://ilcdoc.linearcollider.org/record/618522015ILC Operating Scenarios
http://ilcdoc.linearcollider.org/record/61851
The ILC Technical Design Report documents the design for the construction of a linear collider which can be operated at energies up to 500 GeV. This report summarizes the outcome of a study of possible running scenarios, including a realistic estimate of the real time accumulation of integrated luminosity based on ramp-up and upgrade processes. The evolution of the physics outcomes is emphasized, including running initially at 500 GeV, then at 350 GeV and 250 GeV. The running scenarios have been chosen to optimize the Higgs precision measurements and top physics while searching for evidence for signals beyond the standard model, including dark matter. In addition to the certain precision physics on the Higgs and top that is the main focus of this study, there are scientific motivations that indicate the possibility for discoveries of new particles in the upcoming operations of the LHC or the early operation of the ILC. Follow-up studies of such discoveries could alter the plan for the centre-of-mass collision energy of the ILC and expand the scientific impact of the ILC physics program. It is envisioned that a decision on a possible energy upgrade would be taken near the end of the twenty year period considered in this report.Barklow, TFri, 26 Jun 2015 22:28:19 GMThttp://ilcdoc.linearcollider.org/record/618512015Closure testing NNPDF3.0 with LHC observables
http://ilcdoc.linearcollider.org/record/61849
A thorough understanding of PDFs and their uncertainties is important for the LHC and for future collider experiments. The recently released NNPDF3.0 set was presented alongside results from closure tests, where PDF fits were performed on pseudo-data generated from a chosen input PDF set. The results there demonstrate the validity of the NNPDF methodology and also provide some information about different contributions to the PDF uncertainties. Here I present a number of additional closure test results, specifically an investigation into the effect of using cross-validation in the fits, and an assessment of the successful reproduction of LHC cross-sections in closure tests. The results are consistent with those previously shown in the NNPDF3.0 paper.Deans, Christopher SThu, 25 Jun 2015 22:26:38 GMThttp://ilcdoc.linearcollider.org/record/618492015Supersymmetry: Aspirations and Prospects
http://ilcdoc.linearcollider.org/record/61833
The realization in the early 1980s that weak scale supersymmetry stabilizes the Higgs sector of the spectacularly successful Standard Model led several authors to explore whether low energy supersymmetry could play a role in particle physics. Among these were Richard Arnowitt, Ali Chamseddine and Pran Nath who constructed a viable {\em locally} supersymmetric Grand Unified Theory (GUT), laying down the foundation for supergravity GUT models of particle physics. Supergravity models continue to be explored as one of the most promising extensions of the Standard Model. After a quick overview of some of the issues and aspirations of early researchers working to bring supersymmetry into the mainstream of particle physics, we re-examine early arguments that seemed to imply that superpartners would be revealed in experiments at LEP2 or at the Tevatron. Our purpose is to assess whether the absence of any superpartners in searches at LHC8 presents a crisis for supersymmetry. Toward this end, we re-evaluate fine-tuning arguments that lead to upper bounds on (some) superpartner masses. We conclude that phenomenologically viable superpartner spectra that could arise within a high scale model tuned no worse than a few percent are perfectly possible. While no viable underlying model of particle physics that leads to such spectra has yet emerged, we show that the (supergravity-based) Radiatively-driven Natural Supersymmetry (RNS) framework serves as a surrogate for a phenomenological analysis of an underlying theory with modest fine-tuning. We outline the phenomenological implications of this framework, with emphasis on those LHC and electron-positron collider signatures that might point to the underlying natural origin of gauge and Higgs boson masses. We conclude that the supergravity GUT paradigm laid down in 1982 by Arnowitt, Chamseddine and Nath, and others, remains a vibrant possibility.Tata, XerxesWed, 24 Jun 2015 22:24:59 GMThttp://ilcdoc.linearcollider.org/record/618332015Exploring extended Higgs sectors by radiative corrections with future precision coupling measurements
http://ilcdoc.linearcollider.org/record/61818
In non-minimal Higgs sectors, coupling constants of the discovered Higgs boson can deviate from the predictions in the Standard Model by effects of additional scalar bosons. The pattern of the deviations in various Higgs boson couplings largely depends on the structure of extended Higgs sectors. Therefore, we may be able to determine the true Higgs sector by fingerprinting the predictions on the Higgs boson couplings in each model with the future precision data. As the expected precision is extremely high, it is essentially important to evaluate the theory predictions as accurately as possible with radiative corrections in each model. We calculate a full set of one-loop corrections to the Higgs boson couplings in the two Higgs doublet models with a softly-broken $Z_2$ symmetry, where there are four types of Yukawa interactions. We discuss how to distinguish four types of the model by evaluating the pattern of the deviations in the Yukawa coupling constants and also the couplings with gauge bosons. In addition, we demonstrate how inner parameters in each type of the model can be extracted by the future precision measurements of these couplings at the high luminosity LHC and the International Linear Collider.Kikuchi, MarikoTue, 23 Jun 2015 22:23:13 GMThttp://ilcdoc.linearcollider.org/record/618182015Strong IR Cancellation in Heavy Quarkonium and Precise Top Mass Determination
http://ilcdoc.linearcollider.org/record/61817
Combining recent perturbative analyses on the static QCD potential and the quark pole mass, we find that, for the heavy quarkonium states $c\bar{c}$, $b\bar{b}$ and $t\bar{t}$, (1) ultra-soft (US) corrections in the binding energies are small, and (2) there is a stronger cancellation of IR contributions than what has been predicted by renormalon dominance hypothesis. By contrast, for a hypothetical heavy quarkonium system with a small number of active quark flavors ($n_l\approx 0$), we observe evidence that renormalon dominance holds accurately and that non-negligible contributions from US corrections exist. As an important consequence, we improve on a previous prediction for possible achievable accuracy of top quark $\overline{\rm MS}$--mass measurement at a future linear collider and estimate that in principle about 20 MeV accuracy is reachable.Kiyo, YTue, 23 Jun 2015 22:23:13 GMThttp://ilcdoc.linearcollider.org/record/618172015Physics Case for the International Linear Collider
http://ilcdoc.linearcollider.org/record/61802
We summarize the physics case for the International Linear Collider (ILC). We review the key motivations for the ILC presented in the literature, updating the projected measurement uncertainties for the ILC experiments in accord with the expected schedule of operation of the accelerator and the results of the most recent simulation studies.Fujii, KeisukeMon, 22 Jun 2015 22:21:27 GMThttp://ilcdoc.linearcollider.org/record/618022015Probing the fermionic Higgs portal at lepton colliders
http://ilcdoc.linearcollider.org/record/61790
We study the sensitivity of future electron-positron colliders to UV completions of the fermionic Higgs portal operator $H^\dagger H \bar \chi \chi$. Measurements of precision electroweak $S$ and $T$ parameters and the $e^+e^- \to Zh$ cross section at the CEPC, FCC-ee, and ILC are considered. The scalar completion of the fermionic Higgs portal is closely related to the scalar Higgs portal, and we summarize existing results. We devote the bulk of our analysis to a singlet-doublet fermion completion. Assuming the doublet is sufficiently heavy, we construct the effective field theory (EFT) at dimension-6 in order to compute contributions to the observables. We also provide full one-loop results for $S$ and $T$ in the general mass parameter space. In both completions, future precision measurements can probe the new states at the (multi-)TeV scale, beyond the direct reach of the LHC.Fedderke, Michael AFri, 19 Jun 2015 22:16:38 GMThttp://ilcdoc.linearcollider.org/record/617902015The Pandora Software Development Kit for Pattern Recognition
http://ilcdoc.linearcollider.org/record/61788
The development of automated solutions to pattern recognition problems is important in many areas of scientific research and human endeavour. This paper describes the implementation of the Pandora Software Development Kit, which aids the process of designing, implementing and running pattern recognition algorithms. The Pandora Application Programming Interfaces ensure simple specification of the building-blocks defining a pattern recognition problem. The logic required to solve the problem is implemented in algorithms, with all operations to create or modify event data structures requested by algorithms and performed by the Pandora framework. This design promotes an approach using many decoupled algorithms, each addressing specific topologies. Details of algorithms addressing two pattern recognition problems in High Energy Physics are presented: reconstruction of events at a high-energy e+e- linear collider and reconstruction of cosmic ray or neutrino events in a liquid argon time projection chamber.Marshall, J SThu, 18 Jun 2015 22:14:55 GMThttp://ilcdoc.linearcollider.org/record/617882015Construction and commissioning of a technological prototype of a high-granularity semi-digital hadronic calorimeter
http://ilcdoc.linearcollider.org/record/61787
A large prototype of 1.3m3 was designed and built as a demonstrator of the semi-digital hadronic calorimeter (SDHCAL) concept proposed for the future ILC experiments. The prototype is a sampling hadronic calorimeter of 48 units. Each unit is built of an active layer made of 1m2 Glass Resistive Plate Chamber(GRPC) detector placed inside a cassette whose walls are made of stainless steel. The cassette contains also the electronics used to read out the GRPC detector. The lateral granularity of the active layer is provided by the electronics pick-up pads of 1cm2 each. The cassettes are inserted into a self-supporting mechanical structure built also of stainless steel plates which, with the cassettes walls, play the role of the absorber. The prototype was designed to be very compact and important efforts were made to minimize the number of services cables to optimize the efficiency of the Particle Flow Algorithm techniques to be used in the future ILC experiments. The different components of the SDHCAL prototype were studied individually and strict criteria were applied for the final selection of these components. Basic calibration procedures were performed after the prototype assembling. The prototype is the first of a series of new-generation detectors equipped with a power-pulsing mode intended to reduce the power consumption of this highly granular detector. A dedicated acquisition system was developed to deal with the output of more than 440000 electronics channels in both trigger and triggerless modes. After its completion in 2011, the prototype was commissioned using cosmic rays and particles beams at CERN.Baulieu, GThu, 18 Jun 2015 22:14:55 GMThttp://ilcdoc.linearcollider.org/record/617872015Integrating in the Higgs Portal to Fermion Dark Matter
http://ilcdoc.linearcollider.org/record/61770
Fermion dark matter (DM) interacting with the standard model through a Higgs portal requires non-renormalizable operators, signaling the presence of new mediator states at the electroweak scale. Collider signatures that involve the mediators are a powerful tool to experimentally probe the Higgs portal interactions, providing complementary information to strong constraints set by direct DM detection searches. Indirect detection experiments are less sensitive to this scenario. We investigate the collider reach for the mediators using three minimal renormalizable models as examples, and requiring the fermion DM to be a thermal relic. The Large Hadron Collider in its high-energy, high-luminosity phase can probe most scenarios if DM is lighter than about 200 GeV. Beyond this scale, future high-energy experiments such as an electron-positron collider or a 100-TeV proton-proton collider, combined with future direct detection experiments, are indispensable to conclusively test these models.Freitas, AyresTue, 16 Jun 2015 22:11:31 GMThttp://ilcdoc.linearcollider.org/record/617702015Higgs self-coupling in the MSSM and NMSSM after the LHC Run 1
http://ilcdoc.linearcollider.org/record/61752
Measuring the Higgs self-coupling is one of the crucial physics goals at the LHC Run-2 and other future colliders. In this work, we attempt to figure out the size of SUSY effects on the trilinear self-coupling of the 125 GeV Higgs boson in the MSSM and NMSSM after the LHC Run-1. Taking account of current experimental constraints, such as the Higgs data, flavor constraints, electroweak precision observables and dark matter detections, we obtain the observations: (1) In the MSSM, the ratio of $\lambda^{MSSM}_{3h}/\lambda^{SM}_{3h}$ has been tightly constrained by the LHC data, which can be only slightly smaller than 1 and minimally reach 97\%; (2) In the NMSSM with $\lambda<0.7$, a sizable reduction of $\lambda^{NMSSM}_{3h_2}/\lambda^{SM}_{3h_2}$ can occur and minimally reach 10\% when the lightest CP-even Higgs boson mass $m_{h_1}$ is close to the SM-like Higgs boson $m_{h_2}$ due to the large mixing angle between the singlet and doublet Higgs bosons; (3) In the NMSSM with $\lambda>0.7$, a large enhancement or reduction $-1.1<\lambda^{NMSSM}_{3h_1}/\lambda^{SM}_{3h_1}<2$ can occur, which is accompanied by a sizable change of $h_1\tau^+\tau^-$ coupling. The future colliders, such as the HL-LHC and ILC, will have the capacity to test these large deviations in the NMSSM.Wu, LeiFri, 12 Jun 2015 22:04:55 GMThttp://ilcdoc.linearcollider.org/record/617522015Electron spectra and coherence of radiation in undulators
http://ilcdoc.linearcollider.org/record/61750
Most bright sources of the radiation in hard x-ray and gamma--ray regions are undulator sources and Compton based ones. These sources are ultimate for production of polarized positrons necessary for future linear colliders ILC, CLIC. We developed a novel method for evaluating the energy spectrum of electrons emitting the undulator- and the inverse Compton radiation. The method based on Poisson weighted superposition of electron states is applicable for whole range of the emission intensity per electron pass through the driving force, from much less than unity emitted photons (Compton sources) to many photons emitted (undulators), and for any energy of the photons. The method allows for account contributions in the energy spread both from the Poisson statistics and diffusion due to recoils. The theoretical results were confirmed by simulations. The electron energy spectrum was used for evaluation of the on-axis density of photons and their coherency making use of the `carrier--envelope' presentation for the emitting photons. The evaluated maximum coherency degree of single--electron radiation is evaluated to be proportional to the undulator spatial period and inversely to the energy of electrons, the number of coherently emitted undulator periods almost independent of the undulator deflection parameter. The results of our study are applicable both for the classical limit of classical undulator and for the quantum limit of Compton gamma--ray sources.Bulyak, EugeneThu, 11 Jun 2015 22:03:14 GMThttp://ilcdoc.linearcollider.org/record/617502015Testing general relativity on accelerators
http://ilcdoc.linearcollider.org/record/61707
Within the general theory of relativity, the curvature of space-time is related to the energy and momentum of the present matter and radiation. One of the more specific predictions of general relativity is the deflection of light and particle trajectories in the gravitational field of massive objects. Bending angles for electromagnetic waves and light in particular were measured with a high precision. However, the effect of gravity on relativistic massive particles was never studied experimentally. Here we propose and analyze experiments devoted to that purpose. We demonstrate a high sensitivity of the laser Compton scattering at high energy accelerators to the effects of gravity. The main observable -- maximal energy of the scattered photons -- would experience a significant shift in the ambient gravitational field even for otherwise negligible violation of the equivalence principle. We confirm predictions of general relativity for ultrarelativistic electrons of energy of tens of GeV at a current level of resolution and expect our work to be a starting point of further high-precision studies on current and future accelerators, such as PETRA, European XFEL and ILC.Kalaydzhyan, TigranMon, 08 Jun 2015 21:57:58 GMThttp://ilcdoc.linearcollider.org/record/617072015$\alpha $-Attractors: Planck, LHC and Dark Energy
http://ilcdoc.linearcollider.org/record/61694
We develop four-parameter supergravity models of inflation and dark energy, constrained so that ${\delta\rho\over \rho}$, $n_s$ and the cosmological constant $\Lambda $ take their known observable values, but where the mass of gravitino $m_{3/2}$ and the tensor-to-scalar ratio $r$ are free parameters. We focus on generalized cosmological $\alpha$-attractor models, with logarithmic Kahler potentials, a nilpotent goldstino and spontaneously broken supersymmetry at the de Sitter minimum. The future data on B-modes will specify the parameter $\alpha$, measuring the geometry of the Kahler, manifold. The string landscape idea for dark energy is supported in these models via an incomplete cancellation of the universal positive goldstino and negative gravitino contribution. The scale of SUSY breaking M related to the mass of gravitino in our models is a controllable parameter, independent on the scale of inflation, it will be constrained by LHC data and future collider Energy-frontier experiments.Carrasco, John Joseph MFri, 05 Jun 2015 21:51:53 GMThttp://ilcdoc.linearcollider.org/record/616942015Singlet-like Higgs bosons at present and future colliders
http://ilcdoc.linearcollider.org/record/61592
The presence of extra scalar singlets is a feature of several motivated extensions of the Standard Model, and the mixing of such a singlet with the Higgs boson is allowed to be quite large by current experiments. In this paper we perform a thorough phenomenological study of this possibility. We consider both direct and indirect searches, and we quantify the current constraints as well as the prospects for future hadron and lepton machines - from the forthcoming LHC run up to a futuristic 100 TeV proton-proton collider. The direct reaches are obtained extrapolating the current limits with a technique that we discuss and check with various tests. We find a strong complementarity between direct and indirect searches, with the former dominating for lower values of the singlet mass. We also find that the trilinear Higgs coupling can have sizeable deviations from its Standard Model value, a fact for which we provide an analytical understanding. The results are first presented in a general scalar singlet extension of the Standard Model, taking advantage of the very small number of parameters relevant for the phenomenology. Finally, we specify the same analysis to a few most natural models, i.e. the Next-to-Minimal Supersymmetric Standard Model, Twin Higgs and Composite Higgs.Buttazzo, DarioThu, 21 May 2015 21:21:49 GMThttp://ilcdoc.linearcollider.org/record/615922015Direct searches of extra Higgs boson at future colliders
http://ilcdoc.linearcollider.org/record/61571
We study direct searches of additional Higgs bosons in multi-top-quarks events at the LHC with the collision energy of 14 TeV as well as the International Linear Collider (ILC) with the collision energy of 1 TeV. As a benchmark model, we consider two Higgs doublet models with a softly-broken discrete $Z_2$ symmetry, where the $t\bar t$ decay mode of additional neutral Higgs bosons can be dominant if their masses are heavy enough. Thus, the multi-top-quarks events become an important probe of the extended Higgs sector at future colliders. We estimate the discovery reach at the LHC and the ILC, and find that the search at the ILC can survey the parameter regions where the LHC cannot cover.Yokoya, HiroshiWed, 20 May 2015 21:19:39 GMThttp://ilcdoc.linearcollider.org/record/615712015Phenomenological constraints on light mixed sneutrino WIMP scenarios
http://ilcdoc.linearcollider.org/record/61570
Scenarios where left- and right-handed sneutrinos mix and the lightest mixed one act as a thermal dark matter candidate can solve the dark matter, neutrino mass, and hierarchy problems simultaneously. We focus on the dark matter mass region of the order of 1 GeV, where dark matter direct detections are insensitive. We calculate the decay rate of a false vacuum induced by a large sneutrino trilinear coupling as well as other observables constrained by experiments. As a result, we show that there is an allowed region where the mass of the lightest neutralino is around 1 GeV. The allowed region can be tested by the search for the Higgs boson invisible decay at future colliders.Santa, AkiteruWed, 20 May 2015 21:19:39 GMThttp://ilcdoc.linearcollider.org/record/615702015Collider Interplay for Supersymmetry, Higgs and Dark Matter
http://ilcdoc.linearcollider.org/record/61566
We discuss the potential impacts on the CMSSM of future LHC runs and possible electron-positron and higher-energy proton-proton colliders, considering searches for supersymmetry via MET events, precision electroweak physics, Higgs measurements and dark matter searches. We validate and present estimates of the physics reach for exclusion or discovery of supersymmetry via MET searches at the LHC, which should cover the low-mass regions of the CMSSM parameter space favoured in a recent global analysis. As we illustrate with a low-mass benchmark point, a discovery would make possible accurate LHC measurements of sparticle masses using the MT2 variable, which could be combined with cross-section and other measurements to constrain the gluino, squark and stop masses and hence the soft supersymmetry-breaking parameters m_0, m_{1/2} and A_0 of the CMSSM. Slepton measurements at CLIC would enable m_0 and m_{1/2} to be determined with high precision. If supersymmetry is indeed discovered in the low-mass region, precision electroweak and Higgs measurements with a future circular electron-positron collider (FCC-ee, also known as TLEP) combined with LHC measurements would provide tests of the CMSSM at the loop level. If supersymmetry is not discovered at the LHC, is likely to lie somewhere along a focus-point, stop coannihilation strip or direct-channel A/H resonance funnel. We discuss the prospects for discovering supersymmetry along these strips at a future circular proton-proton collider such as FCC-hh. Illustrative benchmark points on these strips indicate that also in this case FCC-ee could provide tests of the CMSSM at the loop level.Buchmueller, OTue, 19 May 2015 21:17:17 GMThttp://ilcdoc.linearcollider.org/record/615662015