Top Quarks and Electroweak Symmetry Breaking in Little Higgs Models

Aaron Pierce; Maxim Perelstein; Michael E. Peskin

REVIEW

Top Quarks and Electroweak Symmetry Breaking in Little Higgs Models

Maxim Perelstein, Michael E. Peskin, Aaron Pierce

High Energy Physics - Phenomenology · Submitted 3 Oct 2003 · 47 references

Pith's verdict: A careful, honest 2003 phenomenology paper: the load-bearing relation is borrowed and correctly credited, and the genuinely new part is the LHC strategy, whose weak link is b-quark pdf control that the paper names but does not solve.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on November 11, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

T0 AI review An AI read the paper and answered a fixed list of questions.
T1 Audit Automatic checks that the references and files the paper relies on exist and match.
T2 Compute The paper's code or calculations re-run with the same results.
T3 Formal statement The claims written out in a formal math language a computer can read.
T4 Proof Those claims proved, and the proof checked by computer.

How Pith checks papers →

· 3 major objections · 8 minor · Ask about this paper · The compiled record · Read the full review →

Challenge this review Comment (0) Read on arXiv ↗

Cite ▾

arXiv IDhep-ph/0310039 (version 3)

Pith IDGG3ZCZJF, Pith's permanent record of this paper and its review

CitationAaron Pierce, Maxim Perelstein, Michael E. Peskin. "Top Quarks and Electroweak Symmetry Breaking in Little Higgs Models." arXiv:hep-ph/0310039 (2003). https://pith.science/paper/GG3ZCZJF

Cite this reviewBibTeX for Pith's review of this paper

Claim paper

Why Pith says this

Highlight any text to comment on it.

Editor's note

read the letter

Worth your time if you care about the top-partner sector, but read it as a strategy paper, not a discovery paper. The relation everyone quotes from it, m_T/f = (lambda_t^2 + lambda_T^2)/lambda_T (Eq. 10), comes straight out of the one-loop cancellation in Arkani-Hamed et al. [3,4], and the authors say so plainly. What is theirs is the downstream work: the exact tree-level T decay widths and the gaugeless-limit relation Gamma(T->th) ~ Gamma(T->tZ) ~ (1/2)Gamma(T->bW) in Eq. (53), the demonstration that gauging only SU(2)xSU(2)xU(1) rather than the full group relaxes the precision electroweak bound on f enough to keep m_T in LHC range, and the production/decay analysis in Section 4. The vector mass matrices and the S,T shifts in Eq. (43) are worked out explicitly and I could follow them without guessing. That is real, checkable work, and the paper is candid about its own weak points rather than burying them. Section 4.2.1 calls the width measurement 'not very promising' because of jet energy resolution, and Section 4.2.2 states outright that f_b is uncertain at ~20% at x_b = 0.1 and worse above that. The soft spots are exactly where the reader says. The lambda_T extraction needs the b pdf at x_b ~ 0.1-0.2 to roughly 10%, and the Tevatron single-top calibration offered as the fix is described only as 'plausible' -- no demonstration that 2 fb^-1 gets there. Second, the claim that f ~ 1 TeV survives precision electroweak depends on small s_psi and a small triplet vev; Section 3.3 concedes the triplet vev 'can play an important role' and defers to [24] without quantifying how much the allowed f range shrinks. If the triplet vev is generically of order v, m_T drifts above LHC reach and the whole test goes quiet. Both are disclosed, neither is an error. One small thing: the classifier record says no results, methods, or limitations were found -- that is wrong on all three counts, the paper is full of equations and states its limitations explicitly. (The Ubu Roi citation [29] is a pun on the 'royal' triplet, not a real reference; harmless.) Send it to referees. It is a sound, useful paper whose central experimental test depends on pdf control it does not itself supply, and that is a normal thing for a referee to press on.

Referee report

Significance

If the relation of Eq. (10) holds and the T is light enough to be produced at the LHC, the paper turns a model-building statement about electroweak symmetry breaking into a falsifiable prediction with a concrete experimental program. The strengths are explicit and worth naming: the one-loop cancellation is worked through diagram by diagram; the vector boson mass matrices and the resulting precision electroweak shifts are given in closed form rather than quoted; the T branching ratios and the single-T cross section are given as explicit functions of lambda_T and m_T; and the paper is candid about which steps are model-dependent and which measurements are hard. The paper also correctly identifies that the width measurement is limited by jet-mass resolution and that the cross section measurement is limited by the b-quark pdf, which is the right level of honesty for a feasibility study.

Major objections (3)

[Section 4.2.2, Fig. 6, and abstract:s3] The abstract's claim that the Little Higgs mechanism can be tested at the LHC rests on extracting lambda_T from the single-T cross section, and that extraction is proportional to f_b(x_b, Q^2) at x_b ~ 0.1-0.2. The manuscript states the b pdf uncertainty is about 20% at x_b = 0.1 and larger at higher x, and then asserts that a Tevatron single-top calibration 'could result in a measurement of lambda_T^2 at the level of 10% or better.' That number is the load-bearing quantity for the entire testability claim, but no error budget is given: the 5% Tevatron statistical error on sigma(pp -> t + X) is quoted, yet the propagation through the pdf evolution from Q^2 ~ m_t^2 to Q^2 ~ m_T^2, the theory error on the W-boson pdf entering Eq. (67), and the acceptance and background uncertainties in the T -> th -> tbb and T -> bW -> bl nu channels are not estimated. Please either provide a quantitative error budget for lambda_T^2 or soften the '10% or better' statement and the corresponding claim in the Conclusions to a clearly labelled plausibility argument.
[Section 3.3 and the benchmark of Section 4] The conclusion that f can be about 1 TeV, and hence that m_T is in the 2 TeV range accessible at the LHC, depends on the precision electroweak fit of Fig. 3 and Fig. 4, which the manuscript explicitly says omits the vacuum expectation value of the SU(2) triplet pseudo-Goldstone boson and defers to Ref. [24]. The text states that these corrections 'can play an important role in constraining the model for small values of s_psi,' which is precisely the region where the bound on f is weakest and where the benchmark f = 1.2 TeV, m_T = 2.5 TeV sits. Since the naturalness window and the LHC reach are the motivation for the whole feasibility study, please quantify or at least bound how much the allowed f range shrinks for a triplet vev of order v, or state explicitly in Section 4 that the benchmark point presumes a small triplet vev and may not be realized.
[Section 4.2.1, Eq. (54)] The collider analysis is performed in the SU(5)/SO(5) model with the top Lagrangian of Eq. (54), while the relation being tested, Eq. (10), is derived in Section 2 from the simpler SU(3) construction of Eq. (3). The manuscript asserts that the SU(5)/SO(5) model 'belongs to the general class of models for which the formulae of Section 2 are precisely valid' and that 'the relevant Feynman rules for the top quarks are just those shown in Fig. 1,' but does not show the reduction. Because the epsilon-tensor structure of Eq. (54) differs from the linear V_{3i} coupling of Eq. (3), the reader cannot verify from the text that the same lambda_t, lambda_T, and m_T/f relation emerges. Please add the leading-order expansion of Eq. (54) in the Higgs field demonstrating that it reproduces Eq. (3) and hence Eq. (10); this is a short addition but it is what makes the proposed test a test of the model actually used for the LHC study.

Minor objections (8)

[Eq. (12)] The numerical coefficient appears inconsistent: with g' about 0.36, the printed expression 2 sqrt(5) g' f evaluates to roughly 1.6 f, not the quoted 0.3 f. Please check the normalization of the heavy U(1) boson mass.
[Section 3, final paragraph, and Section 4 benchmark] The text argues that naturalness plus precision electroweak data point to m_T of about 2 TeV, and then adopts m_T = 2.5 TeV and f = 1.2 TeV for the analysis. This is a reasonable conservative choice, but a sentence explaining why the benchmark sits above the quoted naturalness value would help the reader.
[Section 4.2.1, Eq. (65)] The total width Gamma_T = m_T lambda_T^2/(16 pi) follows from the three partial widths of Eq. (62) only if the bW mode is twice the other two, as stated in Eq. (53). It would be useful to say explicitly that the factor of four in the denominator relative to a single channel is the sum 1 + 1 + 2 over the three modes.
[Section 4.2.1, width measurement] The estimate that a 5% two-jet mass resolution at 2.5 TeV corresponds to a 125 GeV minimal error is quoted for two-jet final states. The T -> th -> tbb channel has more than two jets in the final state; please state whether the same resolution estimate applies or whether the width measurement is even less favourable there.
[Fig. 3 and Fig. 4] The captions note that the sin psi = 0.1 and 0.2 curves are obscured in Fig. 3, and the figures are dense. A short table of the (S, T) excursion for representative (f, sin psi) points, or an enlargement isolating the small-s_psi curves, would make the electroweak constraint much easier to check.
[Reference [29]] The citation attached to the 'royal' SU(3) triplet is a literary work (Jarry, Ubu Roi). The pun is clear, but the editorial convention of the journal should be checked before publication.
[Section 2, Eq. (2)] The fields Phi and phi appearing in the Goldstone matrix are introduced without definition beyond the remark that they are other members of the multiplet. A one-line statement of their quantum numbers under SU(2) x U(1) would make the embedding of the Higgs doublet unambiguous.
[Section 4.2.2, final paragraph] The proposal to calibrate f_b(x_b, Q^2) using Tevatron single-top data is interesting but is presented without an estimate of the kinematic reach of the 2 fb^-1 sample in x_b. A sentence on the expected statistical reach in x_b, and on how the Q^2 evolution is controlled, would strengthen the argument.

How Pith checks papers → · Full audit of this paper →

The paper

The paper claims

The heavy top partner T of Little Higgs models, expected near 2 TeV, can be found at the LHC and its Higgs coupling measured, giving a direct test of the top-driven origin of electroweak symmetry breaking.

The reading

In the Standard Model the Higgs field gets a negative mass squared, which is what breaks electroweak symmetry, but the model does not explain why. Little Higgs models explain it by making the Higgs a pseudo-Goldstone boson and letting the large top quark Yukawa coupling, together with a new heavy partner of the top called T, generate that negative mass squared through loop corrections. The cancellation of the one-loop quadratic divergence in the Higgs mass forces a relation among four quantities: the T mass, the symmetry-breaking scale f, the top Yukawa coupling, and the T-Higgs coupling lambda_T. That relation, equation (10) of the paper, is the load-bearing prediction: m_T / f = (lambda_t^2 + lambda_T^2) / lambda_T.

Extended reading notes

Core claim

The Little Higgs top sector enforces the relation m_T/f = (lambda_t^2 + lambda_T^2)/lambda_T (equation 10), obtained from the cancellation of the one-loop quadratic divergence in the Higgs mass squared (equation 8). Because lambda_t is known and f, m_T, and lambda_T are in principle measurable at the LHC, observing this relation would be strong evidence for the Little Higgs mechanism of electroweak symmetry breaking.

Load-bearing premise

The proposed test of equation (10) rests on extracting lambda_T from the single-T production cross section, qb -> q'T via longitudinal W exchange (Section 4.2.2, Figure 5). That cross section is proportional to the b-quark pdf at x_b ~ 0.1 to 0.2, which the paper itself states is uncertain at about 20% at x_b = 0.1 and worse at higher x. Without the Tevatron single-top calibration the paper proposes, the lambda_T extraction cannot reach the 10% level the test needs.

Original abstract

`Little Higgs' models, in which the Higgs particle arises as a pseudo-Goldstone boson, have a natural mechanism of electroweak symmetry breaking associated with the large value of the top quark Yukawa coupling. The mechanism typically involves a new heavy SU(2)_{L} singlet top quark, T. We discuss the relationship of the Higgs boson and the two top quarks. We suggest experimental tests of the Little Higgs mechanism of electroweak symmetry breaking using the production and decay of the T at the Large Hadron Collider.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,596 input tokens, $0.0002 reported.

What the abstract itself states, as probabilities: claims first 0.02 · states limitation 0.05 · human participants 0.01 · controlled comparison 0.02 · randomized assignment 0.01 · states quantitative result 0.03 · compares with prior results 0.06 · mentions code or data availability 0.01.

The abstract, sentence by sentence

arXiv listing abstract v3. Results and the main claim are underlined; show every role.

`Little Higgs' models, in which the Higgs particle arises as a pseudo-Goldstone boson, have a natural mechanism of electroweak symmetry breaking associated with the large value of the top quark Yukawa coupling. The mechanism typically involves a new heavy SU(2)_{L} singlet top quark, T. We discuss the relationship of the Higgs boson and the two top quarks. We suggest experimental tests of the Little Higgs mechanism of electroweak symmetry breaking using the production and decay of the T at the Large Hadron Collider.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	`Little Higgs' models, in which the Higgs particle arises as a pseudo-Goldstone boson, have a natural mechanism of electroweak symmetry breaking associated with the large value of the top quark Yukawa coupling.	background 1.00	0.06	0.12	asserted 1.00
s1	The mechanism typically involves a new heavy SU(2)_{L} singlet top quark, T.	background 0.98	0.06	0.06	asserted 0.74
s2	We discuss the relationship of the Higgs boson and the two top quarks.	contribution 0.99	0.77	0.08	unclear 0.67
s3	We suggest experimental tests of the Little Higgs mechanism of electroweak symmetry breaking using the production and decay of the T at the Large Hadron Collider.	future work 0.59	0.68	0.30	hedged possibility 0.90

What kind of paper the classifier reports this is: position or commentary 0.52 · evidence from argument 0.96.

What was examined, and what was not

sources read

arXiv listing abstract v3

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

S sections
T body sentences
C citations
R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures

**Figure 1.** Feynman rules for couplings between the Higgs boso

**Figure 2.** One-loop contributions to the Higgs boson (mass)

**Figure 3.** Excursions in the S −T plane resulting from the SU(5)/SO(5) Little Higgs model with a single gauged U(1). The different lines represent different values of sin ψ={0.1, 0.2, 0.3, . . . 0.7 }, while the points on the lines represent different values of f. The rightmost point (not visible for sin ψ = {0.5, 0.6, 0.7}) is for 1 TeV, and additional points are separated by 500 GeV, increasing in f. The ellipse represents the experimentally allowed region at the 68% confidence level for two degrees of freedom. Also shown is the dark black curve showing the S and T contributions of a…

**Figure 4.** This figure is an enlargement of the central portion

**Figure 5.** The dominant process for T production at the LHC. How well can this cross section be measured at the LHC? The answer obviously depends on the mass of the T quark, as well as on the size of the coupling λT . In

**Figure 6.** Parton level production cross section for the heav

Figures reproduced from arXiv:hep-ph/0310039 by the authors.

References

Works cited (47)

[24]

C. Csaki, J. Hubisz, G. D. Kribs, P. Meade and J. Terning, Phys. Rev. D 68, 035009 (2003) [arXiv:hep-ph/0303236]

View on Pith Pith review arXiv 2003
[29]

A. Jarry, Ubu Roi, Paris: Mercure de France, 1896

View on Pith
[1]

N. Arkani-Hamed, A. G. Cohen and H. Georgi, Phys. Lett. B 513, 232 (2001) [arXiv:hep-ph/0105239]

View on Pith Pith review arXiv 2001
[2]

N. Arkani-Hamed, A. G. Cohen, T. Gregoire and J. G. Wacker, JH EP 0208, 020 (2002) [arXiv:hep-ph/0202089]

View on Pith Pith review arXiv 2002
[3]

N. Arkani-Hamed, A. G. Cohen, E. Katz, A. E. Nelson, T. Gregoir e and J. G. Wacker, JHEP 0208, 021 (2002) [arXiv:hep-ph/0206020]

View on Pith Pith review arXiv 2002
[4]

N. Arkani-Hamed, A. G. Cohen, E. Katz and A. E. Nelson, JHEP 0207, 034 (2002) [arXiv:hep-ph/0206021]

View on Pith Pith review arXiv 2002
[5]

M. Schmaltz, Nucl. Phys. Proc. Suppl. 117, 40 (2003) [arXiv:hep-ph/0210415]

View on Pith Pith review arXiv 2003
[6]

J. G. Wacker, arXiv:hep-ph/0208235

View on Pith Pith review arXiv
[7]

H. Georgi and A. Pais, Phys. Rev. D 12, 508 (1975)

View on Pith 1975
[8]

D. B. Kaplan and H. Georgi, Phys. Lett. B 136, 183 (1984)

View on Pith 1984
[9]

D. B. Kaplan, H. Georgi and S. Dimopoulos, Phys. Lett. B 136, 187 (1984). 24

View on Pith 1984
[10]

K. Inoue, A. Kakuto, H. Komatsu and S. Takeshita, Prog. The or. Phys. 68, 927 (1982) [Erratum-ibid. 70, 330 (1983)]

View on Pith 1982
[11]

L. E. Ibanez, Nucl. Phys. B 218, 514 (1983); L. E. Ibanez and C. Lopez, Phys. Lett. B 126, 54 (1983)

View on Pith 1983
[12]

J. R. Ellis, J. S. Hagelin, D. V. Nanopoulos and K. Tamvakis, Phys. Lett. B 125, 275 (1983)

View on Pith 1983
[13]

L. Alvarez-Gaume, J. Polchinski and M. B. Wise, Nucl. Phys. B 221, 495 (1983)

View on Pith 1983
[14]

C. T. Hill, Phys. Lett. B 266, 419 (1991), Phys. Lett. B 345, 483 (1995) [arXiv:hep-ph/9411426]

View on Pith Pith review arXiv 1991
[15]

A. E. Nelson, arXiv:hep-ph/0304036

View on Pith Pith review arXiv
[16]

I. Low, W. Skiba and D. Smith, Phys. Rev. D 66, 072001 (2002) [arXiv:hep-ph/0207243]

View on Pith Pith review arXiv 2002
[17]

D. E. Kaplan and M. Schmaltz, arXiv:hep-ph/0302049

View on Pith Pith review arXiv
[18]

S. Chang and J. G. Wacker, arXiv:hep-ph/0303001

View on Pith Pith review arXiv
[19]

T. Gregoire, D. R. Smith and J. G. Wacker, arXiv:hep-ph/03052 75

View on Pith
[20]

W. Skiba and J. Terning, arXiv:hep-ph/0305302

View on Pith Pith review arXiv
[21]

S. Chang, arXiv:hep-ph/0306034

View on Pith Pith review arXiv
[22]

C. Csaki, J. Hubisz, G. D. Kribs, P. Meade and J. Terning, Phys. Rev. D 67, 115002 (2003) [arXiv:hep-ph/0211124]

View on Pith Pith review arXiv 2003
[23]

J. L. Hewett, F. J. Petriello and T. G. Rizzo, arXiv:hep-ph/0211 218

View on Pith
[25]

G. Burdman, M. Perelstein and A. Pierce, Phys. Rev. Lett. 90, 241802 (2003) [arXiv:hep-ph/0212228]

View on Pith Pith review arXiv 2003
[26]

T. Han, H. E. Logan, B. McElrath and L. T. Wang, Phys. Rev. D 67, 095004 (2003) [arXiv:hep-ph/0301040]

View on Pith Pith review arXiv 2003
[27]

T. Han, H. E. Logan, B. McElrath and L. T. Wang, Phys. Lett. B 563, 191 (2003) [arXiv:hep-ph/0302188]. 25

View on Pith Pith review arXiv 2003
[28]

B. A. Dobrescu and C. T. Hill, Phys. Rev. Lett. 81, 2634 (1998) [arXiv:hep-ph/9712319]; R. S. Chivukula, B. A. Dobrescu, H. Georg i and C. T. Hill, Phys. Rev. D 59, 075003 (1999) [arXiv:hep-ph/9809470]

View on Pith Pith review arXiv 1998
[30]

http://lepewwg.web.cern.ch/LEPEWWG/

View on Pith
[31]

N. Arkani-Hamed and J. Wacker, personal communication

View on Pith
[32]

H. Georgi and D. B. Kaplan, Phys. Lett. B 145, 216 (1984)

View on Pith 1984
[33]

M. E. Peskin and T. Takeuchi, Phys. Rev. Lett. 65, 964 (1990), Phys. Rev. D 46, 381 (1992)

View on Pith 1990
[34]

M. E. Peskin and J. D. Wells, Phys. Rev. D 64, 093003 (2001) [arXiv:hep-ph/0101342]

View on Pith Pith review arXiv 2001
[35]

The LEP Collaborations, the LEP Electroweak Working Group, an d the SLD Heavy Flavor Group, LEPEWWG/2003-01. http://lepewwg.web.cern.ch/LEPEWWG/stanmod/

View on Pith 2003
[36]

S. C. Bennett and C. E. Wieman, Phys. Rev. Lett. 82, 2484 (1999) [arXiv:hep-ex/9903022]

View on Pith Pith review arXiv 1999
[37]

G. P. Zeller et al. [NuTeV Collaboration], Phys. Rev. Lett. 88, 091802 (2002) [arXiv:hep-ex/0110059]

View on Pith Pith review arXiv 2002
[38]

The existence of the ZH →W +W − decay mode was ﬁrst noted by H. E. Logan, arXiv:hep-ph/0307340

View on Pith Pith review arXiv
[39]

J. D. Bjorken, in New and Exotic Phenomena, Proceedings of the Seventh Moriond Workshop, O. Fackler and J. Tran Thanh Van, eds. ( ´Editions Fronti` eres, 1987)

View on Pith 1987
[40]

See, e.g. J. L. Hewett and T. G. Rizzo, Phys. Rept. 183, 193 (1989). We thank JoAnne Hewett and Tom Rizzo for bringing this point to our attention

View on Pith 1989
[41]

Ian Hinchliﬀe, private communication

View on Pith
[42]

J. C. Collins and W. K. Tung, Nucl. Phys. B 278, 934 (1986)

View on Pith 1986
[43]

F. I. Olness and W. K. Tung, Nucl. Phys. B 308, 813 (1988)

View on Pith 1988
[44]

M. A. Aivazis, F. I. Olness and W. K. Tung, Phys. Rev. Lett. 65, 2339 (1990). 26

View on Pith 1990
[45]

P. M. Nadolsky and Z. Sullivan, in Proc. of the APS/DPF/DPB Summer Study on the Future of Particle Physics (Snowmass 2001) ed. N. Graf, eConf C010630, P510 (2001) [arXiv:hep-ph/0110378]

View on Pith Pith review arXiv 2001
[46]

D. O. Carlson, Ph.D. Thesis, Michigan State U., 1995; arXiv:hep-p h/9508278

View on Pith 1995
[47]

T. Tait and C. P. Yuan, arXiv:hep-ph/9710372. 27

View on Pith Pith review arXiv

Forward citations

Cited by 39 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

The Minimal Composite Higgs Model
hep-ph 2004-12 conditional novelty 8.0 of 10

A five-dimensional AdS model with SO(5) to SO(4) breaking makes the Higgs a composite pseudo-Goldstone boson whose potential is computable, is triggered by top loops, and yields a Higgs lighter than 140 GeV.
Vector-like quark doublets, weak-basis invariants and CP violation
hep-ph 2024-12 conditional novelty 7.0 of 10

Vector-like quark doublets allow CP violation in weak-basis invariants of mass dimension six; the resulting framework organizes the model's parameters, gives the complete CP-odd invariant set for one doublet, and link...
Little Hierarchy, Little Higgses, and a Little Symmetry
hep-ph 2004-05 accept novelty 7.0 of 10

A new discrete symmetry, T-parity, removes all tree-level contributions of TeV-scale little Higgs states to electroweak precision observables, restoring naturalness and predicting a stable dark-matter candidate.
The Impact of Dimension-8 SMEFT Contributions: A Case Study
hep-ph 2021-10 conditional novelty 6.0 of 10

Dimension-8 SMEFT operators from a charge-2/3 vector-like quark change tth production at the LHC by only about 0.5 to 2 percent for allowed parameters, so dimension-6 truncation is adequate here.
Search for vector-like T and B quark pairs in final states with leptons at $\sqrt{s} =$ 13 TeV
hep-ex 2018-05 accept novelty 6.0 of 10

CMS excludes vector-like T quarks below 1140 to 1300 GeV and B quarks below 910 to 1240 GeV at 95% confidence for a range of branching fractions, using 35.9 fb^-1 of 13 TeV data.

Show 34 more citing papers

Trigonometric Parity for the Composite Higgs
hep-ph 2017-09 conditional novelty 6.0 of 10

A new symmetry principle, trigonometric parity, explains why twin-Higgs models cancel quadratic divergences and yields the minimal SO(6)/SO(5) composite Higgs model of neutral naturalness.
A handbook of vector-like quarks: mixing and single production
hep-ph 2013-06 conditional novelty 6.0 of 10

Precision electroweak data bound the mixing of all seven vector-like quark multiplets with the third generation, and a hypercharge -5/6 doublet can fit the LEP Z -> b bbar forward-backward asymmetry with a single mixi...
A First Top Partner Hunter's Guide
hep-ph 2012-11 conditional novelty 6.0 of 10

Four symmetry-constrained simplified models for the lightest top partner in SO(5)/SO(4) composite Higgs are constructed, and existing LHC fourth-generation searches are recast into mass bounds that already reach the n...
Theoretical Constraints on the Higgs Effective Couplings
hep-ph 2009-07 conditional novelty 6.0 of 10

Naturalness, unitarity, and global-symmetry arguments imply that in composite-Higgs and natural models the Higgs coupling to fermions and its gluon-fusion production rate are reduced below Standard Model expectations.
LHC Signals for Warped Electroweak Neutral Gauge Bosons
hep-ph 2007-08 conditional novelty 6.0 of 10

In the warped-extra-dimension framework with bulk gauge fields, the three neutral electroweak Kaluza-Klein states decay sizably to longitudinal W, Z and Higgs, so the LHC can reach 2 TeV with 100 inverse femtobarns an...
Warped/Composite Phenomenology Simplified
hep-ph 2006-12 accept novelty 6.0 of 10

A two-sector effective field theory reproduces the collider phenomenology of warped/composite models using only the Standard Model and its first heavy excitations, with UV-finite Higgs fine-tuning and explicit precisi...
LHC Signals from Warped Extra Dimensions
hep-ph 2006-12 conditional novelty 6.0 of 10

For a warped extra dimension with bulk fermions, 100 inverse femtobarns at the LHC can reveal a Kaluza-Klein gluon up to roughly 4 TeV, using a left-right top polarization asymmetry and boosted top-jet tagging to sepa...
The Intermediate Higgs
hep-ph 2005-04 conditional novelty 6.0 of 10

A pseudo-Nambu-Goldstone Higgs stays natural up to a cutoff near 6 TeV if only the top quark's quadratic divergence is canceled, by new vector-like charge-2/3 quarks, while the gauge divergence is left alone.
Phenomenology of the Littlest Higgs with T-Parity
hep-ph 2004-11 conditional novelty 6.0 of 10

The heavy photon of the littlest Higgs model with T-parity can saturate the observed dark matter relic density, which bounds the symmetry breaking scale f as a function of the Higgs mass and predicts a missing-energy ...
Search for pair production of vector-like quarks in leptonic final states in proton-proton collisions at $\sqrt{s}$ = 13 TeV
hep-ex 2022-09 accept novelty 5.0 of 10

Vector-like T and B quark pair production is excluded at 95% CL for masses up to 1.54 TeV (T) and 1.56 TeV (B), with no excess over standard model backgrounds in 138 fb^-1 of CMS data.
Search for pair production of vector-like quarks in the fully hadronic final state
hep-ex 2019-06 accept novelty 5.0 of 10

No excess appears in fully hadronic 13 TeV CMS data, and vector-like T quarks are excluded below 1370 GeV (tH) and 1040 GeV (bW), with B quarks excluded below 1230 GeV (tW).
Searching for Dark Photons with Maverick Top Partners
hep-ph 2019-04 accept novelty 5.0 of 10

A vector-like top partner charged under a kinetically mixed dark U(1) decays more than 95% of the time into a dark photon or dark Higgs, so QCD pair production at the LHC yields dark photons at rates independent of th...
Search for $\mathrm{t\overline{t}}$H production in the H $\rightarrow$ $\mathrm{b\overline{b}}$ decay channel with leptonic $\mathrm{t\overline{t}}$ decays in proton-proton collisions at $\sqrt{s} =$ 13 TeV
hep-ex 2018-04 accept novelty 5.0 of 10

CMS finds no significant ttH(H→bb) excess in 35.9 fb^-1 at 13 TeV, measuring a signal strength of 0.72 ± 0.45 (1.6σ observed, 2.2σ expected) and setting a 95% CL upper limit of 1.5 times the standard model rate.
Search for pair production of vector-like T and B quarks in single-lepton final states using boosted jet substructure in proton-proton collisions at sqrt(s) = 13 TeV
hep-ex 2017-06 accept novelty 5.0 of 10

No excess of vector-like T or B quark pairs is found in 2.3-2.6 fb^-1 of 13 TeV CMS data, excluding T quark masses below 860 GeV (singlet) and 830 GeV (doublet), and B quark masses below 730 GeV (singlet).
Search for single production of vector-like quarks decaying into a b quark and a W boson in proton-proton collisions at sqrt(s) = 13 TeV
hep-ex 2017-01 accept novelty 5.0 of 10

No excess of vector-like quarks decaying to bW is observed in 2.3 inverse femtobarns of 13 TeV CMS data, excluding Y quarks with coupling 0.5 below 1.40 TeV.
Search for single production of vector-like quarks decaying into $Wb$ in $pp$ collisions at $\sqrt{s} =$ 8 TeV with the ATLAS detector
hep-ex 2016-02 accept novelty 5.0 of 10

No excess of single-produced vector-like T or Y quarks decaying to Wb appears in 8 TeV ATLAS data, giving a 95% CL lower limit of 0.95 TeV (expected 1.10 TeV) on the T quark mass.
Search for pair-produced vectorlike B quarks in proton-proton collisions at sqrt(s) = 8 TeV
hep-ex 2015-07 accept novelty 5.0 of 10

No evidence for pair-produced vectorlike B quarks in 8 TeV CMS data; masses below 740 to 900 GeV are excluded at 95% confidence level, depending on the branching fractions to tW, bZ, and bH.
Odd Top Partners at the LHC
hep-ph 2015-06 conditional novelty 5.0 of 10

A conserved parity that forbids the standard top partner decays can lower the LHC mass bound to roughly 500 GeV, about 300 GeV below the conventional limit, provided the lightest parity-odd scalar lies within about 17...
Light vector-like fermions in a minimal SU(5) setup
hep-ph 2014-01 conditional novelty 5.0 of 10

Light vector-like fermions in a minimal SU(5) setup generate correlated proton decay signatures that could distinguish quark and lepton scenarios, provided the model is extended to achieve gauge coupling unification.
Exotic Decays of the 125 GeV Higgs Boson
hep-ph 2013-12 accept novelty 5.0 of 10

The paper maps about twenty exotic Higgs decay topologies onto the models that produce them and derives new Run 1 limits on several by reinterpreting existing ATLAS and CMS analyses.
Unravelling an extended quark sector through multiple Higgs production?
hep-ph 2012-10 accept novelty 5.0 of 10

In a vector singlet top partner and in a mirror fermion model, precision electroweak data plus the observed single-Higgs rate force gluon-fusion double-Higgs production and H to gamma gamma to stay within roughly 10 t...
Inclusive top-pair production phenomenology with TOPIXS
hep-ph 2012-06 accept novelty 5.0 of 10

Adding the exact NNLO quark-antiquark channel to NNLL soft and Coulomb resummation gives a Tevatron top-pair cross section of 7.15 pb with about 3 percent theory error, and an 8 TeV LHC prediction of 231.8 pb.
A Fermionic Top Partner: Naturalness and the LHC
hep-ph 2012-04 conditional novelty 5.0 of 10

Combining precision electroweak, flavor, and LHC constraints, a fermionic top partner below roughly 500 GeV is excluded, yet a 125 GeV Higgs in this model requires only about 20% fine-tuning.
Updated Status of the Global Electroweak Fit and Constraints on New Physics
hep-ph 2011-07 conditional novelty 5.0 of 10

A global electroweak fit including the first LHC Higgs search data prefers a Higgs mass of 120 GeV and predicts the W mass to 14 MeV, then converts the same data into bounds on new-physics models.
Extra vector-like matter and the lightest Higgs scalar boson mass in low-energy supersymmetry
hep-ph 2009-10 accept novelty 5.0 of 10

Vector-like quark and lepton supermultiplets with fixed-point Yukawa couplings can raise the lightest SUSY Higgs mass by roughly 15 GeV without spoiling gauge coupling unification or precision electroweak fits.
LHC Signals for Warped Electroweak Charged Gauge Bosons
hep-ph 2008-10 conditional novelty 5.0 of 10

Charged KK W bosons in a warped extra dimension can be discovered at the LHC up to about 2 TeV with 100 inverse fb and 3 TeV with 300 inverse fb, mainly via top-bottom and WZ/Wh final states.
Single production of singlet vector-like leptons at the ILC
hep-ph 2024-12 conditional novelty 4.0 of 10

Projected 5-sigma discovery regions for singlet vector-like leptons at the 1 TeV ILC are derived, covering masses 300-700 GeV and coupling kappa down to about 0.026.
Higgs singlet boson as a diphoton resonance in a vector-like quark model
hep-ph 2015-12 conditional novelty 4.0 of 10

A Higgs singlet coupled to vector-like triplet quarks reproduces the 750 GeV diphoton excess with a roughly 1 pb production cross section and a 1.7 percent diphoton branching ratio.
Analysis of events with $b$-jets and a pair of leptons of the same charge in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector
hep-ex 2015-04 accept novelty 4.0 of 10

Same-charge dilepton events with b-jets in 8 TeV ATLAS data show a 2.5 sigma excess over background in the four-top signal regions, too small for a discovery, and yield 95% CL limits on vector-like and chiral heavy quarks.
Jet Substructure at the Tevatron and LHC: New results, new tools, new benchmarks
hep-ph 2011-12 accept novelty 4.0 of 10

A community review and benchmark comparison finds that groomed, hybrid, and jet-shape top taggers outperform subjet-only taggers, while differences among the best methods are comparable to Monte Carlo and detector unc...
Simplified Models for LHC New Physics Searches
hep-ph 2011-05 accept novelty 4.0 of 10

A community workshop produced a standardized catalog of simplified models for LHC new-physics searches, intended to make experimental limits reusable across many theories.
Search for pair-produced vector-like $T$-quarks decaying into $Ht$ final states in the lepton-plus-jets channel in $pp$ collisions at $\sqrt{s}$=13 TeV with the ATLAS detector
hep-ex 2026-05 unverdicted novelty 3.0 of 10

No excess observed in search for vector-like T-quarks in Ht channel; 95% CL mass limits set at 1.40 TeV (SU(2) singlet), 1.56 TeV (doublet), and 1.66 TeV (100% BR to Ht).
LHC signatures of vector-like quarks
hep-ph 2012-07 conditional novelty 3.0 of 10

The paper reviews experimental bounds on vector-like quarks and provides a channel-by-channel map of their LHC production and decay signatures.
Little Higgs Review
hep-ph 2005-02 accept novelty 2.0 of 10

Little Higgs theories keep the Higgs light by making it a pseudo-Nambu-Goldstone boson whose protecting symmetry is broken only collectively, and this review lays out the three canonical constructions and their phenomenology.

How the literature uses it

54 arXiv papers cite this in 57 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 31 sentences without a confident label

Compares with it 2 papers

Previous studies of $∼2$ TeV top partners in traditional little Higgs theories have emphasized the important role of single production of top partners through $Wb$ fusion [ref] , and, while this process still has a large cross section for the $T_a^(u)$, $T_5$, and $T_6$ states [ref] , it no longer overwhelms QCD pair production.[In addition, the state $T_a^(d)$ mixes with the SM left-handed bottom so it can be produced in association with a top quark through an off-shell $W$ boson, but this mode also does not dominate over QCD pair production.] We will focus on strong QCD pair production since it gives more striking collider signatures compared to weak single production.

The Bestest Little Higgs · Collider Phenomenology · 0.81
Also, the parameter space of little Higgs models which satisfies EWPT corresponds to the $W^ '$, $Z^ '$ being weakly coupled to light fermions and strongly coupled to Higgs (including longitudinal $W/Z$) [ref] , just like in the $5D$ models we studied here.

LHC Signals for Warped Electroweak Charged Gauge Bosons · Discussion and Conclusions · 0.82

Cites it as background 23 papers

In the version of the LHM [ref] we will consider in this report, $SU_1(2)×SU_2(2)×U_Y(1) ⊂ SU(5)$ is gauged, which is broken down to the SM gauge group $SU(2)_L×U(1)_Y$.

W physics at the ILC with polarized beams as a probe of the Littlest Higgs Model · The Littlest Higgs Model and $W$ Pair Production at ILC · 0.86
Up-type VLQs, so-called top partners $T$, are ubiquitous in composite [ref] and Little Higgs [ref] models where new fermionic top partners help solve the hierarchy problem.

Searching for Dark Photons with Maverick Top Partners · Introduction · 0.92
In the run-up to the LHC, sum rules in the Little Higgs [ref] and supersymmetric (SUSY) models [ref] have been proposed.

Naturalness Sum Rules and Their Collider Tests · Introduction · 0.99

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.

[1] [24]

C. Csaki, J. Hubisz, G. D. Kribs, P. Meade and J. Terning, Phys. Rev. D 68, 035009 (2003) [arXiv:hep-ph/0303236]

View on Pith Pith review arXiv 2003

[2] [29]

A. Jarry, Ubu Roi, Paris: Mercure de France, 1896

View on Pith

[3] [1]

N. Arkani-Hamed, A. G. Cohen and H. Georgi, Phys. Lett. B 513, 232 (2001) [arXiv:hep-ph/0105239]

View on Pith Pith review arXiv 2001

[4] [2]

N. Arkani-Hamed, A. G. Cohen, T. Gregoire and J. G. Wacker, JH EP 0208, 020 (2002) [arXiv:hep-ph/0202089]

View on Pith Pith review arXiv 2002

[5] [3]

N. Arkani-Hamed, A. G. Cohen, E. Katz, A. E. Nelson, T. Gregoir e and J. G. Wacker, JHEP 0208, 021 (2002) [arXiv:hep-ph/0206020]

View on Pith Pith review arXiv 2002

[6] [4]

N. Arkani-Hamed, A. G. Cohen, E. Katz and A. E. Nelson, JHEP 0207, 034 (2002) [arXiv:hep-ph/0206021]

View on Pith Pith review arXiv 2002

[7] [5]

M. Schmaltz, Nucl. Phys. Proc. Suppl. 117, 40 (2003) [arXiv:hep-ph/0210415]

View on Pith Pith review arXiv 2003

[8] [6]

J. G. Wacker, arXiv:hep-ph/0208235

View on Pith Pith review arXiv

[9] [7]

H. Georgi and A. Pais, Phys. Rev. D 12, 508 (1975)

View on Pith 1975

[10] [8]

D. B. Kaplan and H. Georgi, Phys. Lett. B 136, 183 (1984)

View on Pith 1984

[11] [9]

D. B. Kaplan, H. Georgi and S. Dimopoulos, Phys. Lett. B 136, 187 (1984). 24

View on Pith 1984

[12] [10]

K. Inoue, A. Kakuto, H. Komatsu and S. Takeshita, Prog. The or. Phys. 68, 927 (1982) [Erratum-ibid. 70, 330 (1983)]

View on Pith 1982

[13] [11]

L. E. Ibanez, Nucl. Phys. B 218, 514 (1983); L. E. Ibanez and C. Lopez, Phys. Lett. B 126, 54 (1983)

View on Pith 1983

[14] [12]

J. R. Ellis, J. S. Hagelin, D. V. Nanopoulos and K. Tamvakis, Phys. Lett. B 125, 275 (1983)

View on Pith 1983

[15] [13]

L. Alvarez-Gaume, J. Polchinski and M. B. Wise, Nucl. Phys. B 221, 495 (1983)

View on Pith 1983

[16] [14]

C. T. Hill, Phys. Lett. B 266, 419 (1991), Phys. Lett. B 345, 483 (1995) [arXiv:hep-ph/9411426]

View on Pith Pith review arXiv 1991

[17] [15]

A. E. Nelson, arXiv:hep-ph/0304036

View on Pith Pith review arXiv

[18] [16]

I. Low, W. Skiba and D. Smith, Phys. Rev. D 66, 072001 (2002) [arXiv:hep-ph/0207243]

View on Pith Pith review arXiv 2002

[19] [17]

D. E. Kaplan and M. Schmaltz, arXiv:hep-ph/0302049

View on Pith Pith review arXiv

[20] [18]

S. Chang and J. G. Wacker, arXiv:hep-ph/0303001

View on Pith Pith review arXiv

[21] [19]

T. Gregoire, D. R. Smith and J. G. Wacker, arXiv:hep-ph/03052 75

View on Pith

[22] [20]

W. Skiba and J. Terning, arXiv:hep-ph/0305302

View on Pith Pith review arXiv

[23] [21]

S. Chang, arXiv:hep-ph/0306034

View on Pith Pith review arXiv

[24] [22]

C. Csaki, J. Hubisz, G. D. Kribs, P. Meade and J. Terning, Phys. Rev. D 67, 115002 (2003) [arXiv:hep-ph/0211124]

View on Pith Pith review arXiv 2003

[25] [23]

J. L. Hewett, F. J. Petriello and T. G. Rizzo, arXiv:hep-ph/0211 218

View on Pith

[26] [25]

G. Burdman, M. Perelstein and A. Pierce, Phys. Rev. Lett. 90, 241802 (2003) [arXiv:hep-ph/0212228]

View on Pith Pith review arXiv 2003

[27] [26]

T. Han, H. E. Logan, B. McElrath and L. T. Wang, Phys. Rev. D 67, 095004 (2003) [arXiv:hep-ph/0301040]

View on Pith Pith review arXiv 2003

[28] [27]

T. Han, H. E. Logan, B. McElrath and L. T. Wang, Phys. Lett. B 563, 191 (2003) [arXiv:hep-ph/0302188]. 25

View on Pith Pith review arXiv 2003

[29] [28]

B. A. Dobrescu and C. T. Hill, Phys. Rev. Lett. 81, 2634 (1998) [arXiv:hep-ph/9712319]; R. S. Chivukula, B. A. Dobrescu, H. Georg i and C. T. Hill, Phys. Rev. D 59, 075003 (1999) [arXiv:hep-ph/9809470]

View on Pith Pith review arXiv 1998

[30] [30]

http://lepewwg.web.cern.ch/LEPEWWG/

View on Pith

[31] [31]

N. Arkani-Hamed and J. Wacker, personal communication

View on Pith

[32] [32]

H. Georgi and D. B. Kaplan, Phys. Lett. B 145, 216 (1984)

View on Pith 1984

[33] [33]

M. E. Peskin and T. Takeuchi, Phys. Rev. Lett. 65, 964 (1990), Phys. Rev. D 46, 381 (1992)

View on Pith 1990

[34] [34]

M. E. Peskin and J. D. Wells, Phys. Rev. D 64, 093003 (2001) [arXiv:hep-ph/0101342]

View on Pith Pith review arXiv 2001

[35] [35]

The LEP Collaborations, the LEP Electroweak Working Group, an d the SLD Heavy Flavor Group, LEPEWWG/2003-01. http://lepewwg.web.cern.ch/LEPEWWG/stanmod/

View on Pith 2003

[36] [36]

S. C. Bennett and C. E. Wieman, Phys. Rev. Lett. 82, 2484 (1999) [arXiv:hep-ex/9903022]

View on Pith Pith review arXiv 1999

[37] [37]

G. P. Zeller et al. [NuTeV Collaboration], Phys. Rev. Lett. 88, 091802 (2002) [arXiv:hep-ex/0110059]

View on Pith Pith review arXiv 2002

[38] [38]

The existence of the ZH →W +W − decay mode was ﬁrst noted by H. E. Logan, arXiv:hep-ph/0307340

View on Pith Pith review arXiv

[39] [39]

J. D. Bjorken, in New and Exotic Phenomena, Proceedings of the Seventh Moriond Workshop, O. Fackler and J. Tran Thanh Van, eds. ( ´Editions Fronti` eres, 1987)

View on Pith 1987

[40] [40]

See, e.g. J. L. Hewett and T. G. Rizzo, Phys. Rept. 183, 193 (1989). We thank JoAnne Hewett and Tom Rizzo for bringing this point to our attention

View on Pith 1989

[41] [41]

Ian Hinchliﬀe, private communication

View on Pith

[42] [42]

J. C. Collins and W. K. Tung, Nucl. Phys. B 278, 934 (1986)

View on Pith 1986

[43] [43]

F. I. Olness and W. K. Tung, Nucl. Phys. B 308, 813 (1988)

View on Pith 1988

[44] [44]

M. A. Aivazis, F. I. Olness and W. K. Tung, Phys. Rev. Lett. 65, 2339 (1990). 26

View on Pith 1990

[45] [45]

P. M. Nadolsky and Z. Sullivan, in Proc. of the APS/DPF/DPB Summer Study on the Future of Particle Physics (Snowmass 2001) ed. N. Graf, eConf C010630, P510 (2001) [arXiv:hep-ph/0110378]

View on Pith Pith review arXiv 2001

[46] [46]

D. O. Carlson, Ph.D. Thesis, Michigan State U., 1995; arXiv:hep-p h/9508278

View on Pith 1995

[47] [47]

T. Tait and C. P. Yuan, arXiv:hep-ph/9710372. 27

View on Pith Pith review arXiv