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Rare exclusive hadronic W decays in a [Formula: see text] environment.

Mangano M, Melia T - Eur Phys J C Part Fields (2015)

Bottom Line: The large cross section for [Formula: see text] production at the large hadron collider (LHC) and at any future hadron collider provides a high-statistics and relatively clean environment for a study of W boson properties: after tagging on a leptonic decay of one of the Ws and the two b jets, an additional W still remains in the event.By using strong isolation criteria, which we impose by searching for jets with a single particle constituent, we show that the three-particle hadronic W decays have potential to be measured at the LHC.The possibility of measuring an involved spectrum of decay products could considerably expand our knowledge of how the W decays, and experimental techniques acquired in making these measurements would be useful for application to future measurements of exclusive hadronic Higgs boson decays.

View Article: PubMed Central - PubMed

Affiliation: TH Group, PH Department, CERN, 1211 Geneva 23, Switzerland.

ABSTRACT

The large cross section for [Formula: see text] production at the large hadron collider (LHC) and at any future hadron collider provides a high-statistics and relatively clean environment for a study of W boson properties: after tagging on a leptonic decay of one of the Ws and the two b jets, an additional W still remains in the event. We study the prospect of making the first exclusive hadronic decay of a fundamental boson of the standard model, using the decay modes [Formula: see text] and [Formula: see text], and other related decays. By using strong isolation criteria, which we impose by searching for jets with a single particle constituent, we show that the three-particle hadronic W decays have potential to be measured at the LHC. The possibility of measuring an involved spectrum of decay products could considerably expand our knowledge of how the W decays, and experimental techniques acquired in making these measurements would be useful for application to future measurements of exclusive hadronic Higgs boson decays.

No MeSH data available.


Related in: MedlinePlus

Fraction of signal and backgrounds passing the single particle jet isolation cuts as a function of the parameter
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Fig4: Fraction of signal and backgrounds passing the single particle jet isolation cuts as a function of the parameter

Mentions: The fraction of signal, W-had background, and W-tau background passing these isolation cuts as a function of the parameter are shown in Fig. 4. For both analyses, the W-had background falls off considerably faster than the signal as is increased. Both backgrounds fall so quickly in the case that there is essentially no background in this MC study for . The W-tau background does not fall off for large values of in the analysis. This is caused by events where the tau decays ( of the time) to create the single isolated pion, and where there is a hard, well-separated photon radiated from elsewhere in the event (top, b-quark, initial state, electron). Since the event is relatively empty (with three neutrinos), the cost of this is , and so this background tracks the signal, being below it by a factor of . It is reducible to the extent to which the pion can be identified as coming from a tau decay, using displaced vertex tagging, although given that the tau will be well boosted in the laboratory frame we do not expect this to provide any significant experimental improvement.6 The signal is seen to be less efficient than the , simply because in this case three particles have to pass both transverse momentum and isolation cuts. We plot the shape of the background distributions in the analysis in Fig. 5. The peak of the distributions is driven by the cut on the jets, and lowering this cut moves the peak away from the signal region, which would make a polynomial fit of the background shape more reliable. However, the gain in the number of background events passing the cuts acts in the opposite direction, and after studying a cut of 20 GeV, it appears marginal as to whether one would want to lower the cuts to try and gain sensitivity. The reconstructed W mass from the signal samples is plotted in Fig. 6, for values of used in the below analysis.Fig. 4


Rare exclusive hadronic W decays in a [Formula: see text] environment.

Mangano M, Melia T - Eur Phys J C Part Fields (2015)

Fraction of signal and backgrounds passing the single particle jet isolation cuts as a function of the parameter
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4464735&req=5

Fig4: Fraction of signal and backgrounds passing the single particle jet isolation cuts as a function of the parameter
Mentions: The fraction of signal, W-had background, and W-tau background passing these isolation cuts as a function of the parameter are shown in Fig. 4. For both analyses, the W-had background falls off considerably faster than the signal as is increased. Both backgrounds fall so quickly in the case that there is essentially no background in this MC study for . The W-tau background does not fall off for large values of in the analysis. This is caused by events where the tau decays ( of the time) to create the single isolated pion, and where there is a hard, well-separated photon radiated from elsewhere in the event (top, b-quark, initial state, electron). Since the event is relatively empty (with three neutrinos), the cost of this is , and so this background tracks the signal, being below it by a factor of . It is reducible to the extent to which the pion can be identified as coming from a tau decay, using displaced vertex tagging, although given that the tau will be well boosted in the laboratory frame we do not expect this to provide any significant experimental improvement.6 The signal is seen to be less efficient than the , simply because in this case three particles have to pass both transverse momentum and isolation cuts. We plot the shape of the background distributions in the analysis in Fig. 5. The peak of the distributions is driven by the cut on the jets, and lowering this cut moves the peak away from the signal region, which would make a polynomial fit of the background shape more reliable. However, the gain in the number of background events passing the cuts acts in the opposite direction, and after studying a cut of 20 GeV, it appears marginal as to whether one would want to lower the cuts to try and gain sensitivity. The reconstructed W mass from the signal samples is plotted in Fig. 6, for values of used in the below analysis.Fig. 4

Bottom Line: The large cross section for [Formula: see text] production at the large hadron collider (LHC) and at any future hadron collider provides a high-statistics and relatively clean environment for a study of W boson properties: after tagging on a leptonic decay of one of the Ws and the two b jets, an additional W still remains in the event.By using strong isolation criteria, which we impose by searching for jets with a single particle constituent, we show that the three-particle hadronic W decays have potential to be measured at the LHC.The possibility of measuring an involved spectrum of decay products could considerably expand our knowledge of how the W decays, and experimental techniques acquired in making these measurements would be useful for application to future measurements of exclusive hadronic Higgs boson decays.

View Article: PubMed Central - PubMed

Affiliation: TH Group, PH Department, CERN, 1211 Geneva 23, Switzerland.

ABSTRACT

The large cross section for [Formula: see text] production at the large hadron collider (LHC) and at any future hadron collider provides a high-statistics and relatively clean environment for a study of W boson properties: after tagging on a leptonic decay of one of the Ws and the two b jets, an additional W still remains in the event. We study the prospect of making the first exclusive hadronic decay of a fundamental boson of the standard model, using the decay modes [Formula: see text] and [Formula: see text], and other related decays. By using strong isolation criteria, which we impose by searching for jets with a single particle constituent, we show that the three-particle hadronic W decays have potential to be measured at the LHC. The possibility of measuring an involved spectrum of decay products could considerably expand our knowledge of how the W decays, and experimental techniques acquired in making these measurements would be useful for application to future measurements of exclusive hadronic Higgs boson decays.

No MeSH data available.


Related in: MedlinePlus