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.

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.

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.

CHARM MIXING AND CP VIOLATION AT B-FACTORIES

2014 ◽  
Vol 35 ◽  
pp. 1460413
Author(s):  
GIANLUIGI CIBINETTO ◽  
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
New Physics ◽  
Ratio Analysis ◽  
Charm Meson ◽  
Final State ◽  
Charm Decays ◽  
Decay Modes ◽  
The Standard Model ◽  
Model Predictions

CP violation in charm decays is expected to be very small in the Standard Model, at the level of 0.1% or less. A sizable excess of CP violation with respect to the Standard Model predictions could be a signature of new physics. We report on recent searches for CP violation in charm meson decays at BABAR and Belle experiments. In particular we report a lifetime ratio analysis of D0 → K+K−, π+π− with respect to D0 → K−π+ decays, which is sensitive to [Formula: see text] mixing and CP violation. We report also on searches for CPV in the 3-body D+ → K+K−π+ decay and for decay modes with a [Formula: see text] in the final state, such as [Formula: see text].

scholarly journals Angular and CP-Violation Analyses of B-→D⁎+l-ν-l Decays at Hadron Collider Experiments

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Daniele Marangotto
Keyword(s):  
Standard Model ◽  
Standard Model Prediction ◽  
Hadron Collider ◽  
Simulated Data ◽  
New Physics ◽  
Perfect Reconstruction ◽  
Reconstruction Algorithms ◽  
Final State ◽  
Forward Detector ◽  
The Standard Model

The B-→D⁎+l-ν-l branching fractions ratio between muon and tau lepton decay modes R(D⁎) has shown intriguing discrepancies between the Standard Model prediction and measurements performed at BaBar, Belle, and LHCb experiments, a possible sign of beyond the Standard Model physics. Theoretical studies show how observables related to the B-→D⁎+l-ν-l differential decay distribution can be used to further constrain New Physics contributions, but their experimental measurements are lacking to date. This article proposes the measurement of B-→D⁎+l-ν-l angular and CP-violating observables at hadron collider experiments, by exploiting approximate reconstruction algorithms using information from detectable final-state particles only. The resolution on the phase space variables is studied using B-→D⁎+l-ν-l decays simulated in a forward detector geometry like LHCb. A method to correct the observable values for the reconstruction inaccuracies based on detector simulation is successfully tested on simulated data and the decrease in precision with respect to a perfect reconstruction is evaluated. The D⁎+ longitudinal polarization fraction and the AT(2)CP-violating observable can be measured losing a factor of 2 and 5 in precision, respectively. The extraction of angular distributions from the template fit selecting B-→D⁎+l-ν-l decays and associated systematic uncertainties are also discussed.

scholarly journals Search for K+ → π+νν̅ at NA62

2018 ◽  
Vol 182 ◽  
pp. 02002
Author(s):  
Riccardo Aliberti
Keyword(s):  
Standard Model ◽  
Rare Decay ◽  
New Physics ◽  
Energy Scale ◽  
Beyond The Standard Model ◽  
Fixed Target ◽  
The Standard Model ◽  
Target Experiment ◽  
Flavour Physics ◽  
Fixed Target Experiment

Flavour physics is one of the most powerful fields for the search of new physics beyond the Standard Model. The kaon sector with the rare decay K+ → π+νν̅ provides one of the cleanest and most promising channels. NA62, a fixed target experiment at the CERN SPS, aims to measure BR (K+ → π+νν̅) with 10% precision to test the Standard Model validity up to an energy scale of hundreds of TeV. NA62 had dedicated data taking for the K+ → π+νν̅ measurement in 2016 and 2017 and will continue in 2018. Here preliminary results on a fraction of 2016 dataset are presented. The analysis of the complete 2016 data sample is expected to achieve the SM sensitivity.

scholarly journals Global constraints on neutral-current generalized neutrino interactions

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
F. J. Escrihuela ◽  
L. J. Flores ◽  
O. G. Miranda ◽  
Javier Rendón
Keyword(s):  
Global Analysis ◽  
Neutral Current ◽  
New Physics ◽  
Effective Field ◽  
Global Constraints ◽  
Neutrino Interactions ◽  
Electron Positron ◽  
The Standard Model ◽  
Low Energies ◽  
Positron Collisions

Abstract We study generalized neutrino interactions (GNI) for several neutrino processes, including neutrinos from electron-positron collisions, neutrino-electron scattering, and neutrino deep inelastic scattering. We constrain scalar, pseudoscalar, and tensor new physics effective couplings, based on the standard model effective field theory at low energies. We have performed a global analysis for the different effective couplings. We also present the different individual constraints for each effective parameter (scalar, pseudoscalar, and tensor). Being a global analysis, we show robust results for the restrictions on the different GNI parameters and improve some of these bounds.

MONOJET EVENTS: FROM DARK MATTER TO EXTRA DIMENSIONS, A SEARCH FOR THE EXOTICS USING THE STANDARD MODEL

2013 ◽  
Vol 28 (08) ◽  
pp. 1330012
Author(s):  
PIERRE-HUGUES BEAUCHEMIN ◽  
REYHANEH REZVANI
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Extra Dimensions ◽  
Transverse Energy ◽  
Large Extra Dimensions ◽  
High Energy ◽  
New Physics ◽  
High Transverse Momentum ◽  
Final State ◽  
The Standard Model

Monojet events consist in event topologies with a high transverse momentum jet and a large amount of missing transverse energy. They constitute a promising final state that could lead to phenomena beyond the Standard Model. The theoretical models giving rise to such a signature include the pair production of Weakly Interacting Massive Particles, as dark matter candidates, and models of large extra dimensions. Monojet events can even be used to measure the Standard Model properties of Z boson decays, provided that the precision of the analysis is high enough. Such precision can be achieved by using data-driven determinations of the Standard Model contributions to monojet events. Exotics searches for new physics in such a final state have been performed at all high energy hadronic collider experiments since SPS. The ATLAS and CMS analyses with 7 TeV LHC data provide the latest and most useful information obtained from monojet studies. Their results are presented and discussed in this review paper.

scholarly journals Invisible decays of axion-like particles: constraints and prospects

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Luc Darmé ◽  
Federica Giacchino ◽  
Enrico Nardi ◽  
Mauro Raggi
Keyword(s):  
Dark Sector ◽  
Fixed Target ◽  
Electron Positron ◽  
The Standard Model ◽  
New States ◽  
Target Experiment ◽  
Invisible Decays ◽  
Electron Magnetic Moment ◽  
Photon Coupling ◽  
Fixed Target Experiment

Abstract Axion-like particles (ALPs) can provide a portal to new states of a dark sector. We study the phenomenology of this portal when the ALP mainly decays invisibly, while its interaction with the standard model sector proceeds essentially via its coupling to electrons and/or photons. We reanalyse existing limits from various collider and beam dump experiments, including in particular ALP production via electron/positron interactions, in addition to the usual production through ALP-photon coupling. We further discuss the interplay between these limits and the intriguing possibility of explaining simultaneously the muon and electron magnetic moment anomalies. Finally, we illustrate the prospects of ALP searches at the LNF positron fixed-target experiment PADME, and the future reach of an upgraded experimental setup.

scholarly journals New Physics Beryond the SM at BESIII

2019 ◽  
Vol 212 ◽  
pp. 06004
Author(s):  
Minggang Zhao
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
New Physics ◽  
Dark Sector ◽  
Decay Modes ◽  
The Standard Model ◽  
The Masses

Numerous astrophysical observations strongly suggest the existence of Dark Matter, which provides a hint of dark sector physics. There could exist many dark candidates predicted by theories BSM, such as dark photons and invisible things, that communicate with the Standard Model sector. The masses and decay modes of these particles are expected to be accessible at the BESIII experiment which is the only currently running tau-charm factory with the largest threshold charm samples and some other unique datasets. We have recently performed searches of dark photons and invisible things in several decay modes. Besides, FCNC processes, BNV/LNV processes are also investigated. This talk will summarize the recent results at BESIII on these searches for new physics BSM.

scholarly journals Survival of new physics: Anomaly-free neutral gauge boson at the LHC

2014 ◽  
Vol 29 (08) ◽  
pp. 1450046
Author(s):  
Ying Zhang ◽  
Qing Wang
Keyword(s):  
Standard Model ◽  
Direct Detection ◽  
Decay Channel ◽  
Hadron Collider ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Effective Lagrangian ◽  
Charge Assignment ◽  
Electron Positron ◽  
The Standard Model

An anomaly-free U(1)′ effective Lagrangian as a benchmark of new physics beyond the standard model is proposed to survey the maximal parameter space constrained by the precise electroweak measurements at the Large Electron-Positron Collider (LEP) and direct detection of the dilepton decay channel at [Formula: see text] at the Large Hadron Collider (LHC). By the global fit of the effective couplings of the Z boson to the Standard Model fermions, parameters Δ11, Δ21 and g′′Δ31 related to mixings and r related to the U(1)′ charge assignment are bounded. The allowed areas are plotted not only in the r–g′′ plane, but also in the mZ′–g′′ plane. They show that a sub-TeV Z′ is still permissible as long as the coupling g′′ is of order ~0.01. The results hint at possible new physics beyond the standard model. A prediction of the possible signal for the dilepton decay channel at [Formula: see text] at LHC is also provided.

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