Early LHC phenomenology of Yukawa-bound heavy<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Q</mml:mi><mml:mover accent="true"><mml:mi>Q</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math>mesons

Enkhbat, Tsedenbaljir; Hou, W.-S.; Yokoya, Hiroshi

doi:10.1103/physrevd.84.094013

Cited by 24 publications

(47 citation statements)

References 38 publications

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“…As one can see, putting the Higgs mass m h = 125 GeV the 4G mass difference △m = m t ′ − m b ′ becomes less then the mass of W boson, therefore the semi-leptonic decay channel should be suppressed as was noted in [7].…”

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confidence: 79%

“…But since octet state itself has larger energy compared to singlet one it should decay over time. Besides such a heavy 4G quarks itself should experience weak decay to lighter quarks as well as other decay channels [7]. Since in this paper we are mainly interested on octet channel contribution to production of colour singlet quarkonium below we will calculate its decay width and briefly discuss other decay channels afterwards.…”

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confidence: 99%

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Color-Octet Bound States, Induced by Higgs Mechanism

Bladwell

Дмитриев

Flambaum

et al. 2013

Int. J. Mod. Phys. A

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The current limits for fourth generation quarks allows to expect their mass of the order of 500 GeV. In this mass region for quark-anti-quark pair the additional Yukawa-type attraction due to Higgs mechanism is expected to emerge. This Higgs induced attraction greatly exceeds strong interaction between quarks and leads to the formation of bound states in both colour octet S (8) and singlet Sstates. In the key of recent works on significance of colour octet channel for production of colour singlet state of fourth generation QQ we calculated the binding energies for both octet and singlet states. Such attraction localizes quarks in extremely small area. Hence colour octet pair of fourth generation quarks can form the "nucleus" and together with colour neutralizing light particle that is captured by strong interaction in orbit around the nucleus, create particle, similar by its structure to Deuterium.PACS numbers: 14.80.Bn, 14.65.HaProduction of quarkonium includes both colour-singlet and colour-octet contributions [1]. The octet state can decay into singlet via soft (low energy) gluon emission [2]. As was shown in [3][4][5][6] in certain cases colour-octet mechanism can make dominant contribution to quarkonia production crossection. Since Higgs coupling strength is proportional to the fermion masses the influence of Higgs field on colour-octet state of heavy 4G (4th generation) QQ can be significant.As was discussed in [7] Yukawa-type attraction can lead to the appearance of colour octet 4G QQ ground state. Authors considered pseudo-scalar Nambu-Goldstone mechanism as the main source of coupling. But the latter mechanism requires relativistic effects to be significant while scalar Higgs exchange leads to significant effects already in non-relativistic region. Another model with two Higgs doublets was discussed in [8]. In the light of recent CERN report on discovery of new particle with some properties expected for Higgs boson it appears reasonable to consider it as a main mechanism for 4G quarkonium coupling source. In [9] there was shown that such mechanism significantly increases binding energy of colour-singlet state of 4G quarkonium. In colour-octet state Higgs induced attraction can be the only source of formation of bound state since gluon exchange creates effective repulsion in this case. To show this it is convenient to use variational approach, suggested in [9]. The Hamiltonian of the system is given by the following equation:where T is relativistic kinetic energy, V Y is Yukava-type interaction induced by Higgs exchange:Here m h is Higgs mass, α h = m 2 /(4πv 2 ) is the Higgs field coupling constant. According to standard model Higgs vacuum expectation value v = 246 GeV. Coulomb-like strong interaction V Strong is given by the following expression:where constant a = −α s /6 for octet state and a = 4α s /3 for singlet (α s is strong coupling constant). As one can see, for octet state strong interaction creates effective repulsion. The total energy of the system can be written aswhere V rel and V rad repre...

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confidence: 79%

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confidence: 99%

Color-Octet Bound States, Induced by Higgs Mechanism

Bladwell

Дмитриев

Flambaum

et al. 2013

Int. J. Mod. Phys. A

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“…Unfortunately, their nonperturbative boundstate nature makes the discussion rather speculative, as we have not solved the boundstate problem. We note that the η 1 , η 8 (as well as ρ and σ) states seem, at best, loosely bound [64] at 2m Q ; hence, it would not have been easy to account for a 750 GeV γγ bump anyway. However, if low-lying boundstates exist around TeV, rather than 4-5 TeV, the vector boson multiplicity of the fireball may be reduced, and production may be aided by mixing of ω 8 with the gluon.…”

Section: Discussionmentioning

confidence: 99%

“…If the V L or NG boson G is a massless QQ boundstate (Fermi-Yang redux! ), the leading excitations [64] should be π 8 , ω 1 and ω 8 [65], where G would be π 1 in this notation. Although the hint for a 750 GeV γγ bump in 2015 data at 13 TeV has disappeared with more data [23], it motivates one to consider how low in mass these first excitations could be.…”

Section: Discussionmentioning

confidence: 99%

Connecting Electroweak Symmetry Breaking and Flavor: A Light Dilaton D and a Sequential Heavy Quark Doublet Q

Hou

2018

Symmetry

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Abstract:The 125 GeV boson is quite consistent with the Higgs boson of the Standard Model (SM), but there is a challenge from Anderson as to whether this particle is in the Lagrangian. As Large Hadron Collider (LHC) Run 2 enters its final year of running, we ought to reflect and make sure we have gotten everything right. The ATLAS and CMS combined Run 1 analysis claimed a measurement of 5.4σ vector boson fusion (VBF) production which is consistent with SM, which seemingly refutes Anderson. However, to verify the source of electroweak symmetry breaking (EWSB), we caution that VBF measurement is too important for us to be imprudent in any way, and gluon-gluon fusion (ggF) with similar tag jets must be simultaneous measured, which should be achievable in LHC Run 2. The point is to truly test the dilaton possibility-the pseudo-Goldstone boson of scale invariance violation. We illustrate EWSB by dynamical mass generation of a sequential quark doublet (Q) via its ultrastrong Yukawa coupling and argue how this might be consistent with a 125 GeV dilaton, D. The ultraheavy 2m Q Á 4-5 TeV scale explains the absence of New Physics so far, while the mass generation mechanism shields us from the UV theory for the strong Yukawa coupling. Collider and flavor physics implications are briefly touched upon. Current Run 2 analyses show correlations between the ggF and VBF measurements, but the newly observed ttH production at LHC poses a challenge.Keywords: electroweak symmetry breaking; dilaton; sequential heavy quark doublet PACS: 11.15.Ex; 12.15.Ff; 14.65.Jk; 14.80.´j Higgs, Anderson, and All ThatSpontaneous symmetry breaking (SSB) was introduced into particle physics by Nambu as cross-fertilization from superconductivity (SC). In an explicit model with Jona-Lasinio (NJL), Nambu illustrated [1] how the nucleon mass m N could arise from dynamical chiral symmetry breaking (DχSB), with the pion emerging as a pseudo-Nambu-Goldstone (NG) boson. Subsequent work lead to the Brout-Englert-Higgs (BEH) mechanism [2,3] of electroweak symmetry breaking (EWSB), which became [4,5] part of the Standard Model (SM). The recently discovered 125 GeV boson [6,7] seems consistent with the Higgs boson of SM on every count. This has, in turn, stimulated condensed matter physicists to pursue their own "Higgs" mode.A "Higgs" mode was recently observed [8] in disordered SC films near the SC-insulator quantum critical point, far below the 2∆ double-gap threshold. Here, ∆ is the "energy gap" of the SC phase which is maintained throughout the experiment. This "light Higgs" mode contrasts with "amplitude modes" around 2∆ that were claimed long ago [9]. Anderson, who originated the nonrelativistic version of the BEH mechanism, praised [10] Nambu for elucidating [1] the dynamical generation of m N , a "mass gap", by drawing analogy with SC: a scalar boson in NJL-type of models with mass " 2m N is an

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“…As a mater of fact there are many models with various motivations including models of GUT remnants [32][33][34][35][36][37][38][39], composite models [40][41][42][43][44][45][46][47][48] or a radiative neutrino mass models [49][50][51] which may give such contributions. Among these the scalars are interesting as they may play crucial role in the spontaneous symmetry breaking through additional terms with large portal couplings in the scalar potential.…”

Section: Introductionmentioning

confidence: 99%

Light Leptoquarks and Higgs Pair Production

2016

Proc. Mong. Acad. Sci.

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The data collected by the LHC experiments at 7 and 8 TeV with ~5 and 20fb-1 respectively is refining the details of the Higgs like resonances found last year [1,2]. Many decay channels have been searched for and the individual channels so far have given us a consistent picture with what one expects from the SM Higgs. On the other hand, the self interaction of the Higgs, which is probed by the Higgs pair production [3-7], is too feeble in the SM to be detected with these early data set. Even at 14 TeV run, the luminosity required for probing this process is very high [7-17]. This fact, namely the smallness of the corresponding Higgs pair production cross-section, makes it sensitive to a presence of a new physics [18-31]. In particular, relatively light colored particles are known to affect the cross-section substantially [18-22]. As a mater of fact there are many models with various motivations including models of GUT remnants [32-39], composite models [40-48] or a radiative neutrino mass models [49-51] which may give such contributions. Among these the scalars are interesting as they may play crucial role in the spontaneous symmetry breaking through additional terms with large portal couplings in the scalar potential. In the present work we study the phenomenological consequences of the Standard Model extension by two or more colored scalar particles. As a case study we take several leptoquarks (LQ) since there is an active experimental program by both ATLAS and CMS [52-57] and the lower bounds on their masses have now reached impressive levels some as high as a TeV value. On the other hand simultaneous presence of several LQs, may open up additional channels and therefore weakens these bounds. Specific models where the LQs are introduced to explain a certain phenomenon usually requires more than one LQs as in the model we study here. I examine a possibility of the existence of LQs with masses as light as ~180 GeV and study their effect for the single and di Higgs productions. As we will see the Higgs pair production is substantially altered in the low mass range below 300 GeV without too much change in the Higss diphoton decay channel if portal couplings are large. These couplings are required to have opposite signs by the latest Higgs data or small in magnitude. The model I consider has two LQs, an SU(2) doublet ω and a singlet χ. As we will see their simultaneous presence still allows them to have relatively light masses and escape the current bounds. In particular, the current bounds do not include LQs decaying to τt the masses below 200 GeV. Such a scenario, for example, has appeared in a model considered by Babu and Julio [49], where the light neutrino masses are induced by two-loop effects from LQs. If their masses are only of order few hundred GeV, as it is required in this case, the scenario can be probed or even excluded with the data from the LHC. Therefore this is one of the easiest model which can be tested and is the subject of the current study. Although I consider a particular model, it should be stressed that other models with colored particles can affect the pair productions in a similar manner.In Section II, I briefly list the current experimental status on the Higgs production and decay rates. Then I introduce the model I examined in the paper. Section III contains main part of this work where the numerical results for the single and pair Higgs productions are presented. The conclusion is given in Section IV.

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Early LHC phenomenology of Yukawa-bound heavyQQ¯mesons

Cited by 24 publications

References 38 publications

Color-Octet Bound States, Induced by Higgs Mechanism

Color-Octet Bound States, Induced by Higgs Mechanism

Connecting Electroweak Symmetry Breaking and Flavor: A Light Dilaton D and a Sequential Heavy Quark Doublet Q

Light Leptoquarks and Higgs Pair Production

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