scholarly journals RECENT τ LEPTON RESULTS FROM BABAR

2014 ◽  
Vol 35 ◽  
pp. 1460440
Author(s):  
ALBERTO LUSIANI
Keyword(s):  
Standard Model ◽  
Branching Fractions ◽  
Charged Particles ◽  
Babar Collaboration ◽  
Final States ◽  
Final State ◽  
Experimental Knowledge ◽  
Electron Positron ◽  
The Standard Model ◽  
Positron Collisions

We report recent measurements on τ leptons obtained by the BABAR collaboration using the entire recorded sample of electron-positron collisions at and around the Υ(4S) (about 470fb-1). The events were recorded at the PEP-II asymmetric collider at the SLAC National Accelerator Laboratory. The measurements include high multiplicity τ decay branching fractions with 3 or 5 charged particles in the final state, a search for the second class current the τ decay τ → πη′ν, τ branching fractions into final states containing two KS mesons, [Formula: see text], with h = π, K, and preliminary measurements of hadronic spectra of τ decays with three hadrons (τ- → h-h+h-ντ decays, where h = π, K). The results improve the experimental knowledge of the τ lepton properties and can be used to improve the precision tests of the Standard Model.

scholarly journals Searching for dark sectors in multi lepton final state in e+e− collisions

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Paolo Ciafaloni ◽  
Gabriele Martelli ◽  
Mauro Raggi
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Dark Sector ◽  
Fixed Target ◽  
Final State ◽  
Relative Contribution ◽  
Electron Positron ◽  
The Standard Model ◽  
Experimental Problem ◽  
Positron Collisions

Abstract Electron positron collisions are a very promising environment to search for new physics, and in particular for dark sector related observables. The most challenging experimental problem in detecting dark sector candidates is the very high associated Standard Model background. For this reason it is important to identify observables that are, at the same time, minimally suppressed in the dark sector and highly suppressed in the Standard Model. One example is the e+e− → 3(e+e−) process that can be mediated either by the production and subsequent decay of dark Higgs (h′), e+e− → A′h′ → 6e [1] or produced by the Standards Model process e+e− → 3(e+e−). In the following letter we study the relative contribution to observed e+e− → 3(e+e−) total cross section, coming from the h′ mediated and from the Standard Model processes in the contest of fixed target and low energy collider experiments, with particular attention to the PADME experiment at the INFN Laboratori Nazionali di Frascati.

SEARCH FOR NEW PHYSICS IN eμX DATA AT THE TEVATRON USING SLEUTH: A QUASI-MODEL-INDEPENDENT SEARCH STRATEGY FOR NEW PHYSICS

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 888-890
Author(s):  
◽  
BRUCE KNUTESON
Keyword(s):  
Standard Model ◽  
Search Strategy ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Final States ◽  
Final State ◽  
The Standard Model ◽  
Model Independent

We present a quasi-model-independent search for physics beyond the standard model. We define final states to be studied, and construct a rule that identifies a set of variables appropriate for any particular final state. A new algorithm ("Sleuth") searches for regions of excess in the space of those variables and quantifies the significance of any detected excess. After demonstrating the sensititvity of the method, we apply it to the semi-inclusive channel eμX collected in ≈108 pb -1 of [Formula: see text] collisions at [Formula: see text] at the DØ experiment at the Fermilab Tevatron. We find no evidence of new high pT physics in this sample.

scholarly journals DALITZ ANALYSES: A TOOL FOR PHYSICS WITHIN AND BEYOND THE STANDARD MODEL

2006 ◽  
Vol 21 (27) ◽  
pp. 5503-5512 ◽  
Author(s):  
M. R. PENNINGTON
Keyword(s):  
Standard Model ◽  
Strong Coupling Regime ◽  
Hadronic Decays ◽  
Beyond The Standard Model ◽  
Final States ◽  
Matrix Elements ◽  
Final State ◽  
Ckm Matrix ◽  
The Standard Model ◽  
Final State Interactions

Dalitz analyses are introduced as the method for studying hadronic decays. An accurate description of hadron final states is critical not only to an understanding of the strong coupling regime of QCD, but also to the precision extraction of CKM matrix elements. The relation of such final state interactions to scattering processes is discussed.

scholarly journals MUSiC: a model-unspecific search for new physics in proton–proton collisions at $$\sqrt{s} = 13\,\text {TeV} $$

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Standard Model ◽  
Model Simulation ◽  
Standard Model Prediction ◽  
Proton Collision ◽  
Final States ◽  
Final State ◽  
Data Set ◽  
Proton Proton ◽  
Wide Range ◽  
The Standard Model

AbstractResults of the Model Unspecific Search in CMS (MUSiC), using proton–proton collision data recorded at the LHC at a centre-of-mass energy of 13$$\,\text {TeV}$$ TeV , corresponding to an integrated luminosity of 35.9$$\,\text {fb}^{-1}$$ fb - 1 , are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.

The importance of high-precision hadronic calorimetry to physics

2016 ◽  
Vol 31 (33) ◽  
pp. 1644023 ◽  
Author(s):  
John Hauptman
Keyword(s):  
Standard Model ◽  
High Precision ◽  
Precision Measurement ◽  
High Efficiency ◽  
Branching Fractions ◽  
High Precision Measurement ◽  
High Quality ◽  
Electron Positron ◽  
The Standard Model ◽  
Momentum Resolution

The reconstruction and high-precision measurement of the four-vectors of [Formula: see text] and [Formula: see text] decays to quarks, which constitute nearly 70% of their decay branching fractions, are critical to a high efficiency and high quality experiment. Furthermore, it is crucial that the energy resolution, and consequently the resolution on the invariant mass of the two fragmenting quarks, is comparable to the energy–momentum resolution on the other particles of the standard model, in particular, electrons, photons, and muons, at energies around 100 GeV. I show that this “unification of resolutions” on all particles of the standard model is now in sight, and will lead to excellent physics at an electron–positron collider.

scholarly journals K → μ+μ− as a clean probe of short-distance physics

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Avital Dery ◽  
Mitrajyoti Ghosh ◽  
Yuval Grossman ◽  
Stefan Schacht
Keyword(s):  
Matrix Element ◽  
Standard Model ◽  
Short Distance ◽  
Time Dependent ◽  
Final States ◽  
Interference Effects ◽  
Fundamental Theory ◽  
Long Distance ◽  
Ckm Matrix ◽  
The Standard Model

Abstract The K → μ+μ− decay is often considered to be uninformative of fundamental theory parameters since the decay is polluted by long-distance hadronic effects. We demonstrate that, using very mild assumptions and utilizing time-dependent interference effects, ℬ(KS → μ+μ−)ℓ=0 can be experimentally determined without the need to separate the ℓ = 0 and ℓ = 1 final states. This quantity is very clean theoretically and can be used to test the Standard Model. In particular, it can be used to extract the CKM matrix element combination $$ \mid {V}_{ts}{V}_{td}\sin \left(\beta +{\beta}_s\right)\mid \approx \mid {A}^2{\lambda}^5\overline{\eta}\mid $$ ∣ V ts V td sin β + β s ∣ ≈ ∣ A 2 λ 5 η ¯ ∣ with hadronic uncertainties below 1%.

scholarly journals Search for Heavy Higgs Bosons in Fermionic Decay Channels with CMS

2018 ◽  
Vol 46 ◽  
pp. 1860058
Author(s):  
Ye Chen
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Higgs Bosons ◽  
Final States ◽  
Centre Of Mass ◽  
Decay Channels ◽  
Upper Limits ◽  
The Standard Model ◽  
Cms Detector

Latest results of searches for heavy Higgs bosons in fermionic final states are presented using the CMS detector at the LHC. Results are based on pp collision data collected at centre-of-mass energies of 8 and 13 TeV which have been interpreted according to different extensions of the Standard Model such as MSSM, 2HDM, and NMSSM. These searches look for evidence of other scalar or pseudoscalar bosons, in addition to the observed SM-like 125 GeV Higgs boson, and set 95% confidence level upper limits in fermionic final states and benchmark models explored. The talk reviews briefly the major results obtained by the CMS Collaboration during Run I, and presents the most recent searches performed during Run II.

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