It was recently proposed to extend the Standard Model by means of new spin-1 chiral \(Z^*\) and \(W^{*\pm}\) bosons with the internal quantum numbers of the electroweak Higgs doublets. These bosons ...have unique signatures in transverse momentum, angular and pseudorapidity distributions of the final leptons, which allow one to distinguish them from other heavy resonances. With 40 pb\(^{-1}\) of the LHC proton-proton data at the energy 7 TeV, the ATLAS detector was used to search for narrow resonances in the invariant mass spectrum of \(e^+e^-\) and \(\mu^+\mu^-\) final states and high-mass charged states decaying to a charged lepton and a neutrino. From the search exclusion mass limits of 1.15 TeV\(/c^2\) and 1.35 TeV\(/c^2\) were obtained for the chiral neutral \(Z^*\) and charged \(W^*\) bosons, respectively. These are the first direct limits on the \(W^*\) and \(Z^*\) boson production.
In this review phenomenological consequences of the Standard Model extension by means of new spin-1 chiral fields with the internal quantum numbers of the electroweak Higgs doublets are summarized. ...The prospects for resonance production and detection of the chiral vector
Z
* and
W
*
±
bosons at the LHC energies are considered on the basis of quantitative simulations within the CompHEP/CalcHEP package. The
Z
* boson can be observed as a Breit-Wigner resonance peak in the invariant dilepton mass distributions in the same way as the well-known extra gauge
Z
′ bosons. However, the
Z
* bosons have unique signatures in transverse momentum, angular and pseudorapidity distributions of the final leptons, which allow one to distinguish them from other heavy neutral resonances.
In 2010, with 40 pb
−1
of the LHC proton-proton data at the energy 7 TeV, the ATLAS detector was used to search for narrow resonances in the invariant mass spectrum of
e
+
e
−
and μ
+
μ
−
final states and high-mass charged states decaying to a charged lepton and a neutrino. No statistically significant excess above the Standard Model expectation was observed. The exclusion mass limits of 1.15 and 1.35 TeV/
c
2
were obtained for the chiral neutral
Z
* and charged
W
* bosons, respectively. These are the first direct limits on the
W
* and
Z
* boson production.
Based on the above, a novel strategy for the chiral boson search in the LHC dijet data is discussed. For almost all currently considered exotic models the relevant signal is expected in the central dijet rapidity region
y
1,2
≃ 0 and |
y
1
−
y
2
| ≃ 0. On the contrary, the chiral bosons do not contribute to this region but produce an excess of dijet events far away from it. In particular, for these bosons the appropriate kinematical restrictions lead to a dip in the centrality ratio distribution over the dijet invariant mass instead of a bump expected in the most exotic models.
The facile method of generating internal chirality into the calixarene with two hydroxy groups at the lower rim via an attached chiral substituent has been proposed. The reaction with ...acylisocyanates, catalyzed by a small amount of triethylamine, proceeds forming predominantly one of the two possible calixarene carbamates. The best diastereomeric excess (60 %) has been achieved in the reaction of trichloroacyl isocyanates with 1,3-hydroxycalixarene substituted with the chiral phenylethyl amide moiety. The individual diastereomers of trichloroacetyl-carbamoylcalix4arenas were isolated by crystallization, and their absolute configuration was determined by X-ray diffraction study. The most favored conformations predicted for 1,3-dihydroxy calixarene structures by quantum chemical calculations possess very similar stability. However, the triethylamine molecule preferably connects to the one hydroxyl group of the two available ones, providing the most favorable adduct, which predominantly participates in the reaction with acylisocyanates. This gives rise to the observed diastereomeric excess. The subsequent treatment of the formed carbamoyl with
n
-propyl bromide in presence of NaH and hydrolysis of the product of alkylation easily provide a persistent internally chiral calixarene.
A search for a narrow scalar resonance decaying into an opposite-sign muon pair produced in events with and without b-tagged jets is presented in this paper. The search uses 36.1 fb-1 of $ ...\sqrt{s}=13 $ TeV proton-proton collision data recorded by the ATLAS experiment at the LHC. No significant excess of events above the expected Standard Model background is observed in the investigated mass range of 0.2 to 1.0 TeV. The observed upper limits at 95% confidence level on the cross section times branching ratio for b-quark associated production and gluon-gluon fusion are between 1.9 and 41 fb and 1.6 and 44 fb respectively, which is consistent with expectations. Figure not available: see fulltext..
In this review phenomenological consequences of the Standard Model extension by means of new spin-1 chiral fields with the internal quantum numbers of the electroweak Higgs doublets are summarized. ...The prospects for resonance production and detection of the chiral vector \(Z^*\) and \(W^{*\pm}\) bosons at the LHC energies are considered. The \(Z^*\) boson can be observed as a Breit-Wigner resonance peak in the invariant dilepton mass distributions in the same way as the well-known extra gauge \(Z'\) bosons. However, the \(Z^*\) bosons have unique signatures in transverse momentum, angular and pseudorapidity distributions of the final leptons, which allow one to distinguish them from other heavy neutral resonances. In 2010, with 40 pb\(^{-1}\) of the LHC proton-proton data at the energy 7 TeV, the ATLAS detector was used to search for narrow resonances in the invariant mass spectrum of \(e^+e^-\) and \(\mu^+\mu^-\) final states and high-mass charged states decaying to a charged lepton and a neutrino. No statistically significant excess above the Standard Model expectation was observed. The exclusion mass limits of 1.15 TeV\(/c^2\) and 1.35 TeV\(/c^2\) were obtained for the chiral neutral \(Z^*\) and charged \(W^*\) bosons, respectively. These are the first direct limits on the \(W^*\) and \(Z^*\) boson production. For almost all currently considered exotic models the relevant signal is expected in the central dijet rapidity region. On the contrary, the chiral bosons do not contribute to this region but produce an excess of dijet events far away from it. For these bosons the appropriate kinematic restrictions lead to a dip in the centrality ratio distribution over the dijet invariant mass instead of a bump expected in the most exotic models.
Results of a simulation of Bhabha small-angle scattering process at center-of-mass energy of 240~GeV and at the \(Z\)-boson resonance using the Monte Carlo generator {\tt{ReneSANCe}} are presented. ...For the given accuracy about \(10^{-4}\) in estimating luminosity of future electron-positron accelerators, the minimum cutoff angle for simulated events is established.
A search for excited electrons produced in pp collisions at $\sqrt{s}$ = 13 TeV via a contact interaction $q\overline{q}$ → ee* is presented. The search uses 36.1 fb-1 of data collected in 2015 and ...2016 by the ATLAS experiment at the Large Hadron Collider. Decays of the excited electron into an electron and a pair of quarks ($eq\overline{q}$) are targeted in final states with two electrons and two hadronic jets, and decays via a gauge interaction into a neutrino and a W boson (νW) are probed in final states with an electron, missing transverse momentum, and a large-radius jet consistent with a hadronically decaying W boson. No significant excess is observed over the expected backgrounds. Upper limits are calculated for the pp→ ee*→$eeq\overline{q}$ and pp→ ee*→ eνW production cross sections as a function of the excited electron mass $m_{e*}$ at 95% confidence level. The limits are translated into lower bounds on the compositeness scale parameter Λ of the model as a function of $m_{e*}$. For $m_{e*}$ <0.5 TeV, the lower bound for Λ is 11 TeV. In the special case of $m_{e*}$=Λ, the values of $m_{e*}$< 4.8 TeV are excluded. The presented limits on Λ are more stringent than those obtained in previous searches.
From 2011 to 2014, the BESIII experiment collected about 5 fb−1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing ...the di-muon process e+e− → γISR/FSRμ+μ−, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking.
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