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Minimal spin-one isotriplet dark matter
http://repo.scoap3.org/record/33164
In this work we present a simple extension of the Standard Model that contains, as the only new physics component, a massive spin-one matter field in the adjoint representation of SU(2)L. In order to be consistent with perturbative unitarity, the vector field must be odd under a Z2 symmetry. Radiative corrections make the neutral component of the triplet (V0) slightly lighter than the charged ones. We show that V0 can be the dark matter particle while satisfying all current bounds if it has a mass between 2.8 and 3.8 TeV. We present the current limit on the model parameter space from highly complementary experimental constraints, including dark matter relic density measurement, dark matter direct and indirect detection searches, LHC data on Higgs couplings to photons and LHC data on disappearing track searches. We also show that the two-dimensional parameter space can be fully covered by disappearing track searches at a future 100 TeV hadron collider, which will probe, in particular, the whole mass range relevant for dark matter, thus giving an opportunity to discover or exclude the model.Belyaev, AlexanderFri, 07 Jun 2019 00:16:23 GMThttp://repo.scoap3.org/record/33164APS2019-06-06Next-to-leading-order predictions for single vector-like quark production at the LHC
http://repo.scoap3.org/record/32558
We propose simulation strategies for single production of third generation vector-like quarks at the LHC, implementing next-to-leading-order corrections in QCD and studying in detail their effect on cross sections and differential distributions. We also investigate the differences and the relative incertitudes induced by the use of the Four-Flavour Number Scheme versus the Five-Flavour Number Scheme. As a phenomenological illustration, we concentrate on the production of vector-like quarks coupling to the third generation of the Standard Model in association with a jet and assuming standard couplings to gauge and Higgs bosons.Cacciapaglia, GiacomoThu, 02 May 2019 15:02:29 GMThttp://repo.scoap3.org/record/32558urn:ISSN:0370-2693Elsevier2019-05-20LHC constraints and potential on resonant monotop production
http://repo.scoap3.org/record/31254
We discuss the phenomenology associated with a resonant monotop collider signal, i.e. a signal in which a single top quark is resonantly produced in association with missing energy through an s -channel scalar exchange. We study both the bounds originating from dedicated monotop searches performed by the ATLAS and CMS experiments, and the constraints associated with other processes that could be induced by a new physics context favouring monotop production at colliders. The latter class of constraints includes, in particular, the recasting of analyses from the LHC and the TeVatron. All theoretical calculations are performed at the next-to-leading order accuracy in QCD, and we finally combine all results to establish the present limits on the parameter space and test the relevance of the monotop signal at the LHC Run 2.Cacciapaglia, GiacomoTue, 26 Feb 2019 01:49:58 GMThttp://repo.scoap3.org/record/31254urn:ISSN:1434-6052Springer/Società Italiana di Fisica2019-2-25Vacuum misalignment and pattern of scalar masses in the SU(5)/SO(5) composite Higgs model
http://repo.scoap3.org/record/31048
Composite Higgs models based on SU(5)/SO(5) are characterised by the presence of custodial triplets, like the Georgi-Machacek model. We classify all the operators giving rise to the top mass and Higgs potential in presence of fermion partial compositeness, with top partners in two-index representations of SU(5). A detailed study of each operator allows us to find correlations in the couplings of Higgs and non-Higgs pseudo-Nambu-Goldstone bosons, which depend only on one, two or three independent parameters. We also analyse the Higgs potential, finding that a misalignment along the custodial invariant triplet direction is forbidden by CP conservation. Avoiding custodial breaking allows us to select a handful of feasible models, which feature universal patterns in the scalar masses related to their transformation properties under the custodial symmetry. Finally, we briefly study the LHC phenomenology of the scalars, which are always below 1 TeV even for multi-TeV condensation scales, and find promising same-sign lepton final states enriched by hard photons.Agugliaro, AlessandroMon, 18 Feb 2019 20:22:09 GMThttp://repo.scoap3.org/record/31048urn:ISSN:1029-8479Springer/SISSA2019-02-14Vacuum alignment in a composite 2HDM
http://repo.scoap3.org/record/30750
We study in detail the vacuum structure of a composite two Higgs doublet model based on a minimal underlying theory with 3 Dirac fermions in pseudo-real representations of the condensing gauge interactions, leading to the SU(6)/Sp(6) symmetry breaking pattern. We find that, independently on the source of top mass, the most general CP-conserving vacuum is characterised by three non-vanishing angles. A special case occurs if the Yukawas are aligned, leading to a single angle. In the latter case, a Dark Matter candidate arises, protected by a global U(1) symmetry.Cai, ChengfengSat, 02 Feb 2019 07:57:27 GMThttp://repo.scoap3.org/record/30750urn:ISSN:1029-8479Springer/SISSA2019-01-15The LHC potential of vector-like quark doublets
http://repo.scoap3.org/record/29088
The existence of new vector-like quarks is often predicted by models of new physics beyond the Standard Model, and the development of discovery strategies at colliders is the object of an intense effort from the high-energy community. Our analysis aims at identifying the constraints on and peculiar signatures of simplified scenarios containing two vector-like quark doublets mixing with any of the SM quark generations. This scenario is a necessary ingredient of a broad class of theoretically motivated constructions. We focus on the two charge 2/3 states t 1,2 ′ that, due to their peculiar mixing patterns, feature new production and decay modes that are not searched for at the LHC: single production of the heavier state can dominate over the light one, while pair production via electroweak interactions overcomes the QCD one for masses at the TeV scale.Cacciapaglia, GiacomoFri, 09 Nov 2018 14:13:50 GMThttp://repo.scoap3.org/record/29088urn:ISSN:1029-8479Springer/SISSA2018-11-08Revealing timid pseudo-scalars with taus at the LHC
http://repo.scoap3.org/record/27884
A light pseudo-scalar that is copiously produced at the LHC may still be allowed by present searches. While masses above 65 GeV are effectively covered by di-photon searches, the lower mass window can be tested by a new search for boosted di-tau resonances. We test this strategy on a set of composite Higgs models with top partial compositeness, where most models can be probed with an integrated luminosity below 300 fb-1 .Cacciapaglia, GiacomoThu, 06 Sep 2018 21:31:33 GMThttp://repo.scoap3.org/record/27884urn:ISSN:1434-6052Springer/Società Italiana di Fisica2018-9-6Minimal fundamental partial compositeness
http://repo.scoap3.org/record/26564
Building upon the fundamental partial compositeness framework, we provide consistent and potentially complete composite extensions of the Standard Model. These are used to determine the effective operators emerging at the electroweak scale in terms of the standard model fields upon consistently integrating out the heavy composite dynamics. We exhibit the first effective field theories matching these composite theories of flavor and analyze their physical consequences for the third generation quarks. Relations with other approaches, ranging from effective analyses for partial compositeness to extra dimensions as well as purely fermionic extensions, are briefly discussed. Our methodology is applicable to any composite theory of dynamical electroweak symmetry breaking featuring a complete theory of flavor.Cacciapaglia, GiacomoThu, 05 Jul 2018 20:16:05 GMThttp://repo.scoap3.org/record/26564urn:ISSN:2470-0029APS2018-07-05Common exotic decays of top partners
http://repo.scoap3.org/record/26183
Many standard model extensions that address the hierarchy problem contain Dirac-fermion partners of the top quark, which are typically expected around the TeV scale. Searches for these vector-like quarks mostly focus on their decay into electroweak gauge bosons and Higgs plus a standard model quark. In this article, backed by models of composite Higgs, we propose a set of simplified scenarios, with effective Lagrangians and benchmarks, that include more exotic decay channels, which modify the search strategies and affect the bounds. Analysing several classes of underlying models, we show that exotic decays are the norm and commonly appear with significant rates. All these models contain light new scalars that couple to top partners with charge 5/3, 2/3, and −1/3.Bizot, NicolasWed, 13 Jun 2018 06:36:10 GMThttp://repo.scoap3.org/record/26183urn:ISSN:1029-8479Springer/SISSA2018-06-12Classification of NLO operators for composite Higgs models
http://repo.scoap3.org/record/25101
We provide a general classification of template operators, up to next-to-leading order, that appear in chiral perturbation theories based on the two flavor patterns of spontaneous symmetry breaking SU(NF)/Sp(NF) and SU(NF)/SO(NF). All possible explicit-breaking sources parametrized by spurions transforming in the fundamental and in the two-index representations of the flavor symmetry are included. While our general framework can be applied to any model of strong dynamics, we specialize to composite-Higgs models, where the main explicit breaking sources are a current mass, the gauging of flavor symmetries, and the Yukawa couplings (for the top). For the top, we consider both bilinear couplings and linear ones à la partial compositeness. Our templates provide a basis for lattice calculations in specific models. As a special example, we consider the SU(4)/Sp(4)≅SO(6)/SO(5) pattern which corresponds to the minimal fundamental composite-Higgs model. We further revisit issues related to the misalignment of the vacuum. In particular, we shed light on the physical properties of the singlet η, showing that it cannot develop a vacuum expectation value without explicit CP violation in the underlying theory.Alanne, TommiTue, 24 Apr 2018 06:46:43 GMThttp://repo.scoap3.org/record/25101urn:ISSN:2470-0029APS2018-04-23Anatomy of the inert two-Higgs-doublet model in the light of the LHC and non-LHC dark matter searches
http://repo.scoap3.org/record/23764
The inert two-Higgs-doublet model (i2HDM) is a theoretically well-motivated example of a minimal consistent dark matter (DM) model which provides monojet, mono-Z, mono-Higgs, and vector-boson-fusion+ETmiss signatures at the LHC, complemented by signals in direct and indirect DM search experiments. In this paper we have performed a detailed analysis of the constraints in the full five-dimensional parameter space of the i2HDM, coming from perturbativity, unitarity, electroweak precision data, Higgs data from the LHC, DM relic density, direct/indirect DM detection, and LHC monojet analysis, as well as implications of experimental LHC studies on disappearing charged tracks relevant to a high DM mass region. We demonstrate the complementarity of the above constraints and present projections for future LHC data and direct DM detection experiments to probe further i2HDM parameter space. The model is implemented into the CalcHEP and micrOMEGAs packages, which are publicly available at the HEPMDB database, and it is ready for a further exploration in the context of the LHC, relic density, and DM direct detection.Belyaev, AlexanderThu, 15 Feb 2018 15:31:26 GMThttp://repo.scoap3.org/record/23764urn:ISSN:2470-0029APS2018-02-15Erratum to: Di-boson signatures as standard candles for partial compositeness
http://repo.scoap3.org/record/23203
The sign of C t in appendix C, eqs. (C.1), (C.7), (C.8) needs to be reversed.Belyaev, AlexanderSat, 20 Jan 2018 12:27:06 GMThttp://repo.scoap3.org/record/23203urn:ISSN:1029-8479Springer/SISSA2017-12-15Unification of gauge and Yukawa couplings
http://repo.scoap3.org/record/22389
The unification of gauge and top Yukawa couplings is an attractive feature of gauge-Higgs unification models in extra-dimensions. This feature is usually considered difficult to obtain based on simple group theory analyses. We reconsider a minimal toy model including the renormalisation group running at one loop. Our results show that the gauge couplings unify asymptotically at high energies, and that this may result from the presence of an UV fixed point. The Yukawa coupling in our toy model is enhanced at low energies, showing that a genuine unification of gauge and Yukawa couplings may be achieved.Abdalgabar, AmmarTue, 21 Nov 2017 15:16:55 GMThttp://repo.scoap3.org/record/22389urn:ISSN:0370-2693Elsevier2017-12-09Composite dark matter and Higgs
http://repo.scoap3.org/record/22226
We investigate the possibility that Dark Matter arises as a composite state of a fundamental confining dynamics, together with the Higgs boson. We focus on the minimal SU(4)×SU(4)/SU(4) model which has both a Dark Matter and a Higgs candidates arising as pseudo-Nambu-Goldstone bosons. At the same time, a simple underlying gauge-fermion theory can be defined providing an existence proof of, and useful constraints on, the effective field theory description. We focus on the parameter space where the Dark Matter candidate is mostly a gauge singlet. We present a complete calculation of its relic abundance and find preferred masses between 500 GeV to a few TeV. Direct Dark Matter detection already probes part of the parameter space, ruling out masses above 1 TeV, while Indirect Detection is relevant only if non-thermal production is assumed. The prospects for detection of the odd composite scalars at the LHC are also established.Wu, YongchengTue, 14 Nov 2017 10:49:22 GMThttp://repo.scoap3.org/record/22226urn:ISSN:1029-8479Springer/SISSA2017-11-10Probing vector-like quark models with Higgs-boson pair production
http://repo.scoap3.org/record/20704
We investigate Higgs-boson pair production at the LHC when the final state system arises from decays of vector-like quarks coupling to the Higgs boson and the Standard Model quarks. Our phenomenological study includes next-to-leading-order QCD corrections, which are important to guarantee accurate predictions, and focuses on a detailed analysis of a di-Higgs signal in the four b -jet channel. Whereas existing Run II CMS and ATLAS analyses are not specifically designed for probing non-resonant, vector-like-quark induced, di-Higgs production, we show that they nevertheless offer some potential for these modes. We then investigate the possibility of distinguishing between the various di-Higgs production mechanisms by exploiting the kinematic properties of the signal.Cacciapaglia, GiacomoTue, 04 Jul 2017 10:23:27 GMThttp://repo.scoap3.org/record/20704urn:ISSN:1029-8479Springer/SISSA2017-07-03Di-boson signatures as standard candles for partial compositeness
http://repo.scoap3.org/record/18693
Composite Higgs Models are often constructed including fermionic top partners with a mass around the TeV scale, with the top partners playing the role of stabilizing the Higgs potential and enforcing partial compositeness for the top quark. A class of models of this kind can be formulated in terms of fermionic strongly coupled gauge theories. A common feature they all share is the presence of specific additional scalar resonances, namely two neutral singlets and a colored octet, described by a simple effective Lagrangian. We study the phenomenology of these scalars, both in a model independent and model dependent way, including the bounds from all the available searches in the relevant channels with di-boson and di-top final states. We develop a generic framework which can be used to constrain any model containing pseudo-scalar singlets or octets. Using it, we find that such signatures provide strong bounds on the compositeness scale complementary to the traditional EWPT and Higgs couplings deviations. In many cases a relatively light scalar can be on the verge of discovery as a first sign of new physics.Belyaev, AlexanderTue, 24 Jan 2017 07:08:11 GMThttp://repo.scoap3.org/record/18693urn:ISSN:1029-8479Springer/SISSA2017-01-23Search for a lighter Higgs boson in Two Higgs Doublet Models
http://repo.scoap3.org/record/18312
We consider present constraints on Two Higgs Doublet Models, both from the LHC at Run 1 and from other sources in order to explore the possibility of constraining a neutral scalar or pseudo-scalar particle lighter than the 125 GeV Higgs boson. Such a lighter particle is not yet completely excluded by present data. We show with a simplified analysis that some new constraints could be obtained at the LHC if such a search is performed by the experimental collaborations, which we therefore encourage to continue carrying out light diphoton resonance searches at s = 13 $$ \sqrt{s}=13 $$ TeV in the context of Two Higgs Doublet Models.Cacciapaglia, GiacomoFri, 16 Dec 2016 09:30:10 GMThttp://repo.scoap3.org/record/18312urn:ISSN:1029-8479Springer/SISSA2016-12-15Vector and axial-vector resonances in composite models of the Higgs boson
http://repo.scoap3.org/record/17872
We provide a non-linear realisation of composite Higgs models in the context of the SU(4)/Sp(4) symmetry breaking pattern, where the effective Lagrangian of the spin-0 and spin-1 resonances is constructed via the CCWZ prescription using the Hidden Symmetry formalism. We investigate the EWPT constraints by accounting the effects from reduced Higgs couplings and integrating out heavy spin-1 resonances. This theory emerges from an underlying theory of gauge interactions with fermions, thus first principle lattice results predict the massive spectrum in composite Higgs models. This model can be used as a template for the phenomenology of composite Higgs models at the LHC and at future 100 TeV colliders, as well as for other application. In this work, we focus on the formalism for spin-1 resonances and their bounds from di-lepton and di-boson searches at the LHC.Franzosi, DiogoSat, 12 Nov 2016 14:37:46 GMThttp://repo.scoap3.org/record/17872urn:ISSN:1029-8479Springer/SISSA2016-11-11Towards Kaluza-Klein Dark Matter on nilmanifolds
http://repo.scoap3.org/record/16210
We present a first study of the field spectrum on a class of negatively-curved compact spaces: nilmanifolds or twisted tori. This is a case where analytical results can be obtained, allowing to check numerical methods. We focus on the Kaluza-Klein expansion of a scalar field. The results are then applied to a toy model where a natural Dark Matter candidate arises as a stable massive state of the bulk scalar.Andriot, DavidWed, 29 Jun 2016 10:32:01 GMThttp://repo.scoap3.org/record/16210urn:ISSN:1029-8479Springer/SISSA2016-06-28Dark matter and localised fermions from spherical orbifolds?
http://repo.scoap3.org/record/15217
We study a class of six-dimensional models based on positive curvature surfaces (spherical 2-orbifolds) as extra-spaces. Using the Newman-Penrose formalism, we discuss the particle spectrum in this class of models. The fermion spectrum problem, which has been addressed with flux compactifications in the past, can be avoided using localised fermions. In this framework, we find that there are four types of geometry compatible with the existence of a stable dark matter candidate and we study the simplest case in detail. Using the complementarity between collider resonance searches and relic density constraints, we show that this class of models is under tension, unless the model lies in a funnel region characterised by a resonant Higgs s-channel in the dark matter annihilation.Cacciapaglia, GiacomoFri, 15 Apr 2016 13:20:42 GMThttp://repo.scoap3.org/record/15217urn:ISSN:1029-8479Springer/SISSA2016-04-14Fundamental composite 2HDM: SU(N) with 4 flavours
http://repo.scoap3.org/record/15029
We present a new model of composite Higgs based on a gauged SU(N) group with 4 Dirac fermions in the fundamental representation. At low energy, the model has a global symmetry SU(4)×SU(4) broken to the diagonal SU(4), containing 2 Higgs doublets in the coset. We study in detail the issue of the vacuum alignment. In particular, we prove that, without loss of generality, the vacuum can always be aligned with one doublet. Under certain conditions on the top pre-Yukawas, the second doublet, together with the additional triplets, is stable and can thus play the role of Dark Matter. This model can therefore be an example of composite inert-2HDM model.Ma, TengSun, 03 Apr 2016 08:09:47 GMThttp://repo.scoap3.org/record/15029urn:ISSN:1029-8479Springer/SISSA2016-03-31An ultraviolet chiral theory of the top for the fundamental composite (Goldstone) Higgs
http://repo.scoap3.org/record/14403
We introduce a scalar-less anomaly free chiral gauge theory that serves as natural ultraviolet completion of models of fundamental composite (Goldstone) Higgs dynamics. The new theory is able to generate the top mass and furthermore features a built-in protection mechanism that naturally suppresses the bottom mass. At low energies the theory predicts new fractionally charged fermions, and a number of four-fermion operators that, besides being relevant for the generation of the top mass, also lead to an intriguing phenomenology for the new states predicted by the theory.Cacciapaglia, GiacomoFri, 19 Feb 2016 17:16:40 GMThttp://repo.scoap3.org/record/14403urn:ISSN:0370-2693Elsevier2018-04-18Composite scalars at the LHC: the Higgs, the Sextet and the Octet
http://repo.scoap3.org/record/12927
We present a phenomenological theory of scalar particles that transform as a sextet and an octet of QCD interactions. These particles may arise as light bound states of a fundamental dynamics giving rise to a composite Higgs boson and partial compositeness for the top. As a concrete example, we discuss an explicit UV completion based on the SU(4)/Sp(4) coset, where QCD colour is carried by additional fundamental fermions charged under the confining gauge group. Top partners, as well as potentially even lighter coloured scalars, arise as bound states of the coloured fermions. We study production and detection at LHC Run I and II of the octet and sextet, setting lower limits on masses and couplings to Standard Model particles using existing 8 TeV analyses. We finally explore prospects for the ongoing 13 TeV Run II: we focus on final states with two same sign leptons, that have the potential to discriminate the sextet.Cacciapaglia, GiacomoFri, 04 Dec 2015 17:56:39 GMThttp://repo.scoap3.org/record/12927urn:ISSN:1029-8479Springer/SISSA2015-11-30Interplay of vector-like top partner multiplets in a realistic mixing set-up
http://repo.scoap3.org/record/11725
The ATLAS and CMS collaborations at the LHC have performed analyses on the existing data sets, studying the case of one vector-like fermion or multiplet coupling to the standard model Yukawa sector. In the near future, with more data available, these experimental collaborations will start to investigate more realistic cases. The presence of more than one extra vector-like multiplet is indeed a common situation in many extensions of the standard model. The interplay of these vector-like multiplet between precision electroweak bounds, flavour and collider phenomenology is a important question in view of establishing bounds or for the discovery of physics beyond the standard model. In this work we study the phenomenological consequences of the presence of two vector-like multiplets. We analyse the constraints on such scenarios from tree-level data and oblique corrections for the case of mixing to each of the SM generations. In the present work, we limit to scenarios with two top-like partners and no mixing in the down-sector.Cacciapaglia, GiacomoTue, 08 Sep 2015 23:52:07 GMThttp://repo.scoap3.org/record/11725urn:ISSN:1029-8479Springer/SISSA2015-09-02Anarchic Yukawas and top partial compositeness: the flavour of a successful marriage
http://repo.scoap3.org/record/10752
The top quark can be naturally singled out from other fermions in the Standard Model due to its large mass, of the order of the electroweak scale. We follow this reasoning in models of pseudo Nambu Goldstone Boson composite Higgs, which may derive from an underlying confining dynamics. We consider a new class of flavour models, where the top quark obtains its mass via partial compositeness, while the lighter fermions acquire their masses by a deformation of the dynamics generated at a high flavour scale. One interesting feature of such scenario is that it can avoid all the flavour constraints without the need of flavour symmetries, since the flavour scale can be pushed high enough. We show that both flavour conserving and violating constraints can be satisfied with top partial compositeness without invoking any flavour symmetry for the up-type sector, in the case of the minimal SO(5)/SO(4) coset with top partners in the four-plet and singlet of SO(4). In the down-type sector, some degree of alignment is required if all down-type quarks are elementary. We show that taking the bottom quark partially composite provides a dynamical explanation for the hierarchy causing this alignment. We present explicit realisations of this mechanism which do not require to include additional bottom partner fields. Finally, these conclusions are generalised to scenarios with non-minimal cosets and top partners in larger representations.Cacciapaglia, GiacomoMon, 22 Jun 2015 18:09:35 GMThttp://repo.scoap3.org/record/10752urn:ISSN:1029-8479Springer/SISSA2015-06-15