scholarly journals Jet substructure from dark sector showers

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Timothy Cohen ◽  
Joel Doss ◽  
Marat Freytsis
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Jet Substructure ◽  
Dark Sector ◽  
Collider Phenomenology ◽  
Point Energy ◽  
Strongly Coupled ◽  
Quark Masses ◽  
Physics Model ◽  
Gauge Structure

Abstract We examine the robustness of collider phenomenology predictions for a dark sector scenario with QCD-like properties. Pair production of dark quarks at the LHC can result in a wide variety of signatures, depending on the details of the new physics model. A particularly challenging signal results when prompt production induces a parton shower that yields a high multiplicity of collimated dark hadrons with subsequent decays to Standard Model hadrons. The final states contain jets whose substructure encodes their non-QCD origin. This is a relatively subtle signature of strongly coupled beyond the Standard Model dynamics, and thus it is crucial that analyses incorporate systematic errors to account for the approximations that are being made when modeling the signal. We estimate theoretical uncertainties for a canonical substructure observable designed to be sensitive to the gauge structure of the underlying object, the two-point energy correlator $$ {e}_2^{\left(\beta \right)} $$ e 2 β , by computing envelopes between resummed analytic distributions and numerical results from Pythia. We explore the separability against the QCD background as the confinement scale, number of colors, number of flavors, and dark quark masses are varied. Additionally, we investigate the uncertainties inherent to modeling dark sector hadronization. Simple estimates are provided that quantify one’s ability to distinguish these dark sector jets from the overwhelming QCD background. Such a search would benefit from theory advances to improve the predictions, and the increase in statistics using the data to be collected at the high luminosity LHC.

scholarly journals D → Klv semileptonic decay using lattice QCD with HISQ at physical pion masses

2018 ◽  
Vol 175 ◽  
pp. 13027 ◽  
Author(s):  
Bipasha Chakraborty ◽  
Christine Davies ◽  
Jonna Koponen ◽  
G Peter Lepage
Keyword(s):  
Standard Model ◽  
Lattice Qcd ◽  
Semileptonic Decay ◽  
Light Quark ◽  
Form Factors ◽  
New Physics ◽  
Ckm Matrix ◽  
Quark Masses ◽  
The Standard Model ◽  
Fertile Ground

he quark flavor sector of the Standard Model is a fertile ground to look for new physics effects through a unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix. We present a lattice QCD calculation of the scalar and the vector form factors (over a large q2 region including q2 = 0) associated with the D→ Klv semi-leptonic decay. This calculation will then allow us to determine the central CKM matrix element, Vcs in the Standard Model, by comparing the lattice QCD results for the form factors and the experimental decay rate. This form factor calculation has been performed on the Nf = 2 + 1 + 1 MILC HISQ ensembles with the physical light quark masses.

scholarly journals The THDMa Revisited

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2341
Author(s):  
Tania Robens
Keyword(s):  
Dark Matter ◽  
Parameter Space ◽  
B Physics ◽  
A Priori ◽  
New Physics ◽  
Dark Sector ◽  
The Standard Model ◽  
Future Collider ◽  
Physics Model ◽  
Scalar Sector

The THDMa is a new physics model that extends the scalar sector of the Standard Model by an additional doublet as well as a pseudoscalar singlet and allows for mixing between all possible scalar states. In the gauge-eigenbasis, the additional pseudoscalar serves as a portal to the dark sector, with a priori any dark matter spins states. The option where dark matter is fermionic is currently one of the standard benchmarks for the experimental collaborations, and several searches at the LHC constrain the corresponding parameter space. However, most current studies constrain regions in parameter space by setting all but 2 of the 12 free parameters to fixed values. In this work, we performed a generic scan on this model, allowing all parameters to float. We applied all current theoretical and experimental constraints, including bounds from current searches, recent results from B-physics, in particular Bs→Xsγ, as well as bounds from astroparticle physics. We identify regions in the parameter space which are still allowed after these were applied and which might be interesting for an investigation of current and future collider machines.

scholarly journals Electroweak corrections to the fermionic decays of heavy Higgs states

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Florian Domingo ◽  
Sebastian Paßehr
Keyword(s):  
Standard Model ◽  
Scalar Fields ◽  
Higgs Doublet ◽  
New Physics ◽  
Higgs Bosons ◽  
Light Higgs Boson ◽  
Collider Phenomenology ◽  
The One ◽  
Three Body ◽  
Electroweak Corrections

Abstract Extensions of the standard model often come with additional, possibly electroweakly charged Higgs states, the prototypal example being the Two-Higgs-Doublet Model. While collider phenomenology does not exclude the possibility for some of these new scalar fields to be light, it is relatively natural to consider masses in the multi-TeV range, in which case the only remaining light Higgs boson automatically receives SM-like properties. The appearance of a hierarchy between the new-physics states and the electroweak scale then leads to sizable electroweak corrections, e. g. in the decays of the heavy Higgs bosons, which are dominated by effects of infrared type, namely Sudakov logarithms. Such radiative contributions obviously affect the two-body decays, but should also be paired with the radiation of electroweak gauge bosons (or lighter Higgs bosons) for a consistent picture at the one-loop order. Resummation of the leading terms is also relatively easy to achieve. We re-visit these questions in the specific case of the fermionic decays of heavy Higgs particles in the Next-to-Minimal Supersymmetric Standard Model, in particular pointing out the consequences of the three-body final states for the branching ratios of the heavy scalars.

scholarly journals PROBE THE EFFECTS OF SPLIT SUSY IN RARE B DECAYS

2006 ◽  
Vol 21 (14) ◽  
pp. 1137-1150 ◽  
Author(s):  
CHUAN-HUNG CHEN ◽  
CHAO-QIANG GENG
Keyword(s):  
Standard Model ◽  
Parity Violation ◽  
Branching Ratio ◽  
New Physics ◽  
B Decays ◽  
The Standard Model ◽  
Order Of Magnitude ◽  
Physics Model ◽  
Split Supersymmetry ◽  
New Interactions

We study the decays of B→K(*)ℓ+ℓ- in split supersymmetry with R-parity violation. We find that the decay branching ratio of B→Kτ+τ- in the new physics model due to the scalar interactions can be 1.8×10-6 which is about one order of magnitude larger than in the standard model, whereas those of B→Kℓ+ℓ- (ℓ=e and μ) and the K* modes are insensitive to the new physics. On the other hand, the forward–backward asymmetries of B→Kτ+τ- and Kμ+μ-, vanishing in the standard model, can be over 10 and 1%, respectively. In addition, we show that the new interactions will significantly change the forward–backward asymmetry in B→K*τ+τ-.

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 Constraining electroweakinos in the minimal Dirac gaugino model

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Mark Goodsell ◽  
Sabine Kraml ◽  
Humberto Reyes-González ◽  
Sophie L. Williamson
Keyword(s):  
Standard Model ◽  
Supersymmetric Standard Model ◽  
Direct Detection ◽  
Small Mass ◽  
New Physics ◽  
Low Energy ◽  
Collider Phenomenology ◽  
Supersymmetric Models ◽  
Relic Abundance ◽  
Frequent Presence

Supersymmetric models with Dirac instead of Majorana gaugino masses have distinct phenomenological consequences. In this paper, we investigate the electroweakino sector of the Minimal Dirac Gaugino Supersymmetric Standard Model (MDGSSM) with regards to dark matter (DM) and collider constraints. We delineate the parameter space where the lightest neutralino of the MDGSSM is a viable DM candidate, that makes for at least part of the observed relic abundance while evading constraints from DM direct detection, LEP and low-energy data, and LHC Higgs measurements. The collider phenomenology of the thus emerging scenarios is characterised by the richer electroweakino spectrum as compared to the Minimal Supersymmetric Standard Model (MSSM) -6 neutralinos and 3 charginos instead of 4 and 2 in the MSSM, naturally small mass splittings, and the frequent presence of long-lived particles, both charginos and/or neutralinos. Reinterpreting ATLAS and CMS analyses with the help of SmodelS and MadAnalysis 5, we discuss the sensitivity of existing LHC searches for new physics to these scenarios and show which cases can be constrained and which escape detection. Finally, we propose a set of benchmark points which can be useful for further studies, designing dedicated experimental analyses and/or investigating the potential of future experiments.

Implementation of the CMS-TOP-18-003 analysis in the MadAnalysis 5 framework (four top quarks with at least two leptons; 137 fb−1)

2020 ◽  
pp. 2141008
Author(s):  
Luc Darmé ◽  
Benjamin Fuks
Keyword(s):  
Standard Model ◽  
Center Of Mass ◽  
Top Quarks ◽  
New Physics ◽  
Proton Proton ◽  
Proton Collisions ◽  
Center Of Mass Energy ◽  
The Standard Model ◽  
Physics Model ◽  
Proton Proton Collisions

We present the implementation in MadAnalysis 5 of the CMS-TOP-18-003 search for the production of four top quarks in the Standard Model and detail the validation of this implementation. This CMS analysis studies Standard Model four-top production through the same-sign and multi-lepton plus jets channels, using a luminosity of 137 fb[Formula: see text] of proton-proton collisions at a center-of-mass energy of 13 TeV. We validate our implementation work by studying various distributions and event counts describing the properties of the signal in the context of the Standard Model: jet and [Formula: see text]-jet multiplicities, the hadronic activity [Formula: see text], and the number of expected events populating the various analysis signal regions. We then provide a small example of usage of this implementation to constrain a toy new physics model.

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 BEYOND THE STANDARD MODEL WITH B AND K PHYSICS

2004 ◽  
Vol 19 (06) ◽  
pp. 907-917 ◽  
Author(s):  
Y. GROSSMAN
Keyword(s):  
Standard Model ◽  
Extra Dimension ◽  
Flavor Physics ◽  
New Physics ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Model Predictions ◽  
Physics Model ◽  
K Physics

In the first part of the talk the flavor physics input to models beyond the Standard Model is described. One specific example of such a new physics model is given: a model with bulk fermions in one non-factorizable extra dimension. In the second part of the talk we discuss several observables that are sensitive to new physics. We explain what type of new physics can produce deviations from the Standard Model predictions in each of these observables.

scholarly journals Beyond Standard Model Searches in the MiniBooNE Experiment

2015 ◽  
Vol 2015 ◽  
pp. 1-19 ◽  
Author(s):  
Teppei Katori ◽  
Janet M. Conrad
Keyword(s):  
Beyond Standard Model ◽  
Standard Model ◽  
Lorentz Violation ◽  
New Physics ◽  
Standard Model Extension ◽  
Dark Sector ◽  
Short Baseline ◽  
Neutrino Sector ◽  
The Standard Model ◽  
Neutrino Experiments

The MiniBooNE experiment has contributed substantially to beyond standard model searches in the neutrino sector. The experiment was originally designed to test theΔm2~1 eV2region of the sterile neutrino hypothesis by observingνe(ν-e) charged current quasielastic signals from aνμ(ν-μ) beam. MiniBooNE observed excesses ofνeandν-ecandidate events in neutrino and antineutrino mode, respectively. To date, these excesses have not been explained within the neutrino standard model (νSM); the standard model extended for three massive neutrinos. Confirmation is required by future experiments such as MicroBooNE. MiniBooNE also provided an opportunity for precision studies of Lorentz violation. The results set strict limits for the first time on several parameters of the standard-model extension, the generic formalism for considering Lorentz violation. Most recently, an extension to MiniBooNE running, with a beam tuned in beam-dump mode, is being performed to search for dark sector particles. This review describes these studies, demonstrating that short baseline neutrino experiments are rich environments in new physics searches.

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