Distinguishing spins in decay chains at the large hadron collider

Athanasiou, Christiana; Lester, C. G.; Smillie, Jennifer M.; Webber, B.R.

doi:10.1088/1126-6708/2006/08/055

Cited by 85 publications

(148 citation statements)

References 14 publications

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“…Conservation of KK-parity is very central to the phenomenology of MUED and is similar in its ramifications to R-parity of SUSY scenarios. Vigorous efforts are on [8,11,14,41,42,43,44,45,47,46,48,49,50,51,52,53,54,55,56,57] in chalking out strategies and their respective efficiencies to distinguish between these two contending scenarios under different situations. These efforts broadly exploits two salient differences between the two scenarios.…”

Section: Introductionmentioning

confidence: 99%

Search for Higgs bosons of the universal extra dimensions at the large Hadron collider

Bandyopadhyay

Bhattacherjee

Datta

2010

J. High Energ. Phys.

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The Higgs sector of the Universal Extra Dimensions (UED) has a rather involved setup. With one extra space dimension, the main ingredients to the construct are the higher Kaluza-Klein (KK) excitations of the Standard Model Higgs boson and the fifth components of the gauge fields which on compactification appear as scalar degrees of freedom and can mix with the former thus leading to physical KK-Higgs states of the scenario. In this work, we explore in detail the phenomenology of such a Higgs sector of the UED with the Large Hadron Collider (LHC) in focus. We work out relevant decay branching fractions involving the KK-Higgs excitations. Possible production modes of the KK-Higgs bosons are then discussed with an emphasis on their associated production with the third generation KK-quarks and that under the cascade decays of strongly interacting UED excitations which turn out to be the only phenomenologically significant modes. It is pointed out that the collider searches of such Higgs bosons face generic hardship due to soft end-products which result from severe degeneracies in the masses of the involved excitations in the minimal version of the UED (MUED). Generic implications of either observing some or all of the KK-Higgs bosons at the LHC are discussed.

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Section: Introductionmentioning

confidence: 99%

Search for Higgs bosons of the universal extra dimensions at the large Hadron collider

Bandyopadhyay

Bhattacherjee

Datta

2010

J. High Energ. Phys.

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“…FIGURE 6. Shapes of dilepton spectra in the cascade decays of new heavy particles at the LHC, for different sequences of spins (left) [34], and the sensitivity of a lepton asymmetry to a CP-violating phase in a supersymmetric model (right) [35].…”

Section: Hadron-hadron Collisionsmentioning

confidence: 99%

“…There are many observables capable of distinguishing these spin signatures, such as the shape of the ℓℓ spectrum shown in the left panel of Fig. 6, the shape of the qℓ spectrum and its angular asymmetry as a function of its invariant mass [34].…”

Section: Hadron-hadron Collisionsmentioning

confidence: 99%

Polarization puts a New Spin on Physics

Ellis¹

2007

AIP Conference Proceedings

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Abstract. Polarization and spin effects are useful for probing the Standard Model, in both the electroweak sector and the strong sector, where the spin decomposition of the nucleon is still a hot topic, with important new data on the net polarizations of the gluon and the strange quarks. Spin phenomena are also useful in searches for new physics, for example via measurements of the anomalous magnetic moment of the muon and searches for electric dipole moments. The cross sections for the direct detection of dark matter may also have an important spin-dependent component, related to the spin decomposition of the nucleon, that could be an important diagnostic tool. Polarization effects are also important diagnostic aids for high-energy experiments at electronproton, proton-proton and electron-positron colliders.

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“…[21,22], here we shall limit our discussion 2 only to particles of spin 1 or less, namely we shall consider spin 0 scalars (S), spin 1/2 fermions (F) and spin 1 vector particles (V). table 1 lists the 6 spin configurations for the decay chain of figure 1, which were also considered in [21,22]. Five of these six possibilities can be readily accommodated in either supersymmetric or UED models.…”

Section: Introductionmentioning

confidence: 99%

A general method for model-independent measurements of particle spins, couplings and mixing angles in cascade decays with missing energy at hadron colliders

Burns¹,

Kong²,

Matchev³

et al. 2008

J. High Energy Phys.

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We outline a general strategy for measuring spins, couplings and mixing angles in the case of a heavy partner decay chain terminating in an invisible particle. We consider the common example of a heavy scalar or fermion D decaying sequentially to other heavy particles C, B and A by emitting a quark jet j and two leptons ℓ ± n and ℓ ∓ f . We derive analytic formulas for the dilepton ({ℓ + ℓ − }) and the two jet-lepton ({jℓ n } and {jℓ f }) invariant mass distributions for the case of most general couplings and mixing angles of the heavy partners. We then consider various spin assignments for the heavy particles A, B, C and D, and for each case, derive the relevant functional basis for the invariant mass distributions which contains the intrinsic spin information and does not depend on the couplings and mixing angles. We propose a new method for determining the spins of the heavy partners, using the three experimentally observable distributions {ℓ + ℓ − }, {jℓ + } + {jℓ − } and {jℓ + } − {jℓ − }. We show that the former two only depend on a single model-dependent parameter α, while the latter may depend on two other parameters β and γ. By fitting these distributions to our set of basis functions, we are able to do a pure measurement of the spins per se. Our method is also applicable at a pp collider such as the Tevatron, for which the previously proposed lepton charge asymmetry is identically zero and does not contain any spin information. In the process of determining the spins, we also end up with an independent measurement of the parameters α, β and γ, which represent certain combinations of the couplings and the mixing angles of the heavy partners A, B, C and D.

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Distinguishing spins in decay chains at the large hadron collider

Cited by 85 publications

References 14 publications

Search for Higgs bosons of the universal extra dimensions at the large Hadron collider

Search for Higgs bosons of the universal extra dimensions at the large Hadron collider

Polarization puts a New Spin on Physics

A general method for model-independent measurements of particle spins, couplings and mixing angles in cascade decays with missing energy at hadron colliders

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