scholarly journals Study of excited $$\varvec{\varXi }$$ baryons with the $$\overline{\text{ P }}$$ANDA detector

2021 ◽  
Vol 57 (4) ◽  
Author(s):  
G. Barucca ◽  
F. Davì ◽  
G. Lancioni ◽  
P. Mengucci ◽  
L. Montalto ◽  
...  

AbstractThe study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards $$N^*$$ N ∗ and $$\varDelta $$ Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the $$N^*$$ N ∗ and $$\varDelta $$ Δ spectra. The future antiproton experiment $$\overline{\text{ P }}$$ P ¯ ANDA will provide direct access to final states containing a $${\overline{\varXi }}\varXi $$ Ξ ¯ Ξ pair, for which production cross sections up to $$\mu \text{ b }$$ μ b are expected in $$\bar{\text{ p }}$$ p ¯ p reactions. With a luminosity of $$L=10^{31}$$ L = 10 31 cm$$^{-2}$$ - 2 s$$^{-1}$$ - 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of $$\sim 10^6\, \text{ events }/\text{day }$$ ∼ 10 6 events / day . With a nearly $$4\pi $$ 4 π detector acceptance, $$\overline{\text{ P }}$$ P ¯ ANDA will thus be a hyperon factory. In this study, reactions of the type $$\bar{\text{ p }}$$ p ¯ p $$\rightarrow $$ → $${\overline{\varXi }}^{+}$$ Ξ ¯ + $$\varXi ^{*-}$$ Ξ ∗ - as well as $$\bar{\text{ p }}$$ p ¯ p $$\rightarrow $$ → $${\overline{\varXi }}^{*+}$$ Ξ ¯ ∗ + $$\varXi ^{-}$$ Ξ - with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.

2021 ◽  
Vol 57 (4) ◽  
Author(s):  
J. Adamczewski-Musch ◽  
◽  
A. Belyaev ◽  
A. Blanco ◽  
C. Blume ◽  
...  

AbstractA feasibility study has been performed in order to investigate the performance of the HADES  detector to measure the electromagnetic decays of the hyperon resonances $$\Sigma (1385)^{0}$$ Σ ( 1385 ) 0 ,  $$\Lambda (1405)$$ Λ ( 1405 )   and $$\Lambda (1520)$$ Λ ( 1520 )   as well as the production of double strange baryon systems $$\Xi ^{-}$$ Ξ -  and $$\Lambda $$ Λ $$\Lambda $$ Λ  in p + p reactions at a beam kinetic energy of $$4.5\,{\mathrm{GeV}}$$ 4.5 GeV . The existing HADES  detector will be upgraded by a new Forward Detector, which extends the detector acceptance into a range of polar angles that plays a crucial role for these investigations. The analysis of each channel is preceded by a consideration of the production cross-sections. Afterwards the expected signal count rates using a target consisting of either liquid hydrogen or polyethylene are summarized.


2018 ◽  
Vol 33 (11) ◽  
pp. 1841003
Author(s):  
Jun Cao ◽  
Yu-Qi Li ◽  
Yao-Bei Liu

The Georgi–Machacek (GM) model predicts the existence of the doubly-charged scalars [Formula: see text], which can be seen the typical particles in this model and their diboson decay channels are one of the most promising ways to discover such new doubly-charged scalars. Based on the constraints of the latest combined ATLAS and CMS Higgs boson diphoton signal strength data at [Formula: see text] confidence level, we focus on the study of the triple scalar production in [Formula: see text] collisions at the future International Linear collider (ILC): [Formula: see text], where the production cross-sections are very sensitive to the triple scalar coupling parameter [Formula: see text]. Considering the typical same-sign diboson decay modes for the doubly-charged scalars, the possible final signals might be detected via this process at the future ILC experiments.


2019 ◽  
Vol 79 (11) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
O. Abdinov ◽  
...  

Abstract The production cross-sections for $$W^{\pm }$$W± and Z bosons are measured using ATLAS data corresponding to an integrated luminosity of 4.0 pb$$^{-1}$$-1 collected at a centre-of-mass energy $$\sqrt{s}=2.76$$s=2.76 TeV. The decay channels $$W \rightarrow \ell \nu $$W→ℓν and $$Z \rightarrow \ell \ell $$Z→ℓℓ are used, where $$\ell $$ℓ can be an electron or a muon. The cross-sections are presented for a fiducial region defined by the detector acceptance and are also extrapolated to the full phase space for the total inclusive production cross-section. The combined (average) total inclusive cross-sections for the electron and muon channels are: $$\begin{aligned} \sigma ^{\text {tot}}_{W^{+}\rightarrow \ell \nu }= & {} 2312 \pm 26\ (\text {stat.})\\&\pm 27\ (\text {syst.}) \pm 72\ (\text {lumi.}) \pm 30\ (\text {extr.})~\text {pb} , \\ \sigma ^{\text {tot}}_{W^{-}\rightarrow \ell \nu }= & {} 1399 \pm 21\ (\text {stat.})\ \pm 17\ (\text {syst.}) \\&\pm 43\ (\text {lumi.}) \pm 21\ (\text {extr.})~\text {pb} , \\ \sigma ^{\text {tot}}_{Z \rightarrow \ell \ell }= & {} 323.4 \pm 9.8\ (\text {stat.}) \pm 5.0\ (\text {syst.})\\&\pm 10.0\ (\text {lumi.}) \pm 5.5 (\text {extr.}) ~\text {pb} . \end{aligned}$$σW+→ℓνtot=2312±26(stat.)±27(syst.)±72(lumi.)±30(extr.)pb,σW-→ℓνtot=1399±21(stat.)±17(syst.)±43(lumi.)±21(extr.)pb,σZ→ℓℓtot=323.4±9.8(stat.)±5.0(syst.)±10.0(lumi.)±5.5(extr.)pb.Measured ratios and asymmetries constructed using these cross-sections are also presented. These observables benefit from full or partial cancellation of many systematic uncertainties that are correlated between the different measurements.


2016 ◽  
Vol 31 (28) ◽  
pp. 1630025
Author(s):  
Daniel Britzger

New and recent results on QCD measurements from the H1 and ZEUS experiments at the HERA ep collider are reviewed. The final results on the combined deep-inelastic neutral and charged current cross-sections are presented and their role in the extractions of parton distribution functions (PDFs) is studied. The PDF fits give insight into the compatibility of QCD evolution and heavy flavor schemes with the data as a function of kinematic variables such as the scale Q2. Measurements of jet production cross-sections in ep collisions provide direct proves of QCD and extractions of the strong coupling constants are performed. Charm and beauty cross-section measurements are used for the determination of the heavy quark masses. Their role in PDF fits is investigated. In the regime of diffractive DIS and photoproduction, dijet and prompt photon production cross-sections provide insights into the process of factorization and the nature of the diffractive exchange.


2004 ◽  
Vol 19 (06) ◽  
pp. 864-876
Author(s):  
R. HIROSKY

The success of the theory of Quantum Chromodynamics (QCD) in describing processes controlled by the strong interaction is generally seen as a triumph of modern particle physics. This paper reviews recent QCD measurements using hadronic jet final states from the Fermilab Tevatron, DESY's HERA, and CERN's LEP colliders. Recent advancements in the measurements of jet production cross sections, events shapes, and energy flow, along with improved theoretical calculations, allow for new levels of precision in the study of the physics of strong interactions and point to areas in need of further refinement.


Author(s):  
M. Aaboud ◽  
◽  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
...  

Abstract A search for excited electrons produced in pp collisions at $$\sqrt{s}$$s  = 13 $$\text {Te}\text {V}$$Te via a contact interaction $$q{\bar{q}}\rightarrow ee^*$$qq¯→ee∗ is presented. The search uses 36.1 fb$$^{-1}$$-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 ($$eq{\bar{q}}$$eqq¯) are targeted in final states with two electrons and two hadronic jets, and decays via a gauge interaction into a neutrino and a $$W$$W boson ($$\nu W$$νW) are probed in final states with an electron, missing transverse momentum, and a large-radius jet consistent with a hadronically decaying $$W$$W boson. No significant excess is observed over the expected backgrounds. Upper limits are calculated for the $$pp \rightarrow ee^*\rightarrow eeq{\bar{q}} $$pp→ee∗→eeqq¯ and $$pp \rightarrow ee^*\rightarrow e\nu W $$pp→ee∗→eνW production cross sections as a function of the excited electron mass $$m_{e^*}$$me∗ at 95% confidence level. The limits are translated into lower bounds on the compositeness scale parameter $$\Lambda $$Λ of the model as a function of $$m_{e^*}$$me∗. For $$m_{e^*} <0.5$$me∗<0.5 $$\text {Te}\text {V}$$Te, the lower bound for $$\Lambda $$Λ is 11 $$\text {Te}\text {V}$$Te. In the special case of $$m_{e^*} =\Lambda $$me∗=Λ, the values of $$m_{e^*} <4.8$$me∗<4.8 $$\text {Te}\text {V}$$Te are excluded. The presented limits on $$\Lambda $$Λ are more stringent than those obtained in previous searches.


2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Hluf Negash ◽  
Shashank Bhatnagar

We calculate the double charmonium production cross-section within the framework of 4×4 Bethe-Salpeter Equation in the electron-positron annihilation, at center of mass energy s=10.6GeV, that proceeds through the exchange of a single virtual photon. In this calculation, we make use of the full Dirac structure of 4D BS wave functions of these charmonia, with the incorporation of all the Dirac covariants (both leading and subleading). The calculated cross-sections for the double charmonium productions for final states, (J/Ψ,ηc), (Ψ′,ηc), (J/Ψ,ηc′), and (Ψ′,ηc′), are close to experimental data and in broad agreement with results of other theoretical models.


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