scholarly journals The see-saw portal at future Higgs Factories

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Daniele Barducci ◽  
Enrico Bertuzzo ◽  
Andrea Caputo ◽  
Pilar Hernandez ◽  
Barbara Mele
Keyword(s):  
Center Of Mass ◽  
New Physics ◽  
Neutrino Masses ◽  
New Production ◽  
Indirect Measurements ◽  
Decay Modes ◽  
Higher Dimensional ◽  
Lepton Colliders ◽  
The Standard Model ◽  
The Impact

Abstract We consider an extension of the Standard Model with two right-handed singlet fermions with mass at the electroweak scale that induce neutrino masses, plus a generic new physics sector at a higher scale Λ. We focus on the effective operators of lowest dimension d = 5, which induce new production and decay modes for the singlet fermions. We assess the sensitivity of future Higgs Factories, such as FCC-ee, CLIC-380, ILC and CEPC, to the coefficients of these operators for various center of mass energies. We show that future lepton colliders can test the cut-off of the theory up to Λ ≃ 500–1000 TeV, surpassing the reach of future indirect measurements of the Higgs and Z boson widths. We also comment on the possibility of determining the underlying model flavor structure should a New Physics signal be observed, and on the impact of higher dimensional d = 6 operators on the experimental signatures.

High(est) energy lepton colliders

2021 ◽  
pp. 2142016
Author(s):  
Roberto Franceschini
Keyword(s):  
Standard Model ◽  
Center Of Mass ◽  
High Energy ◽  
New Physics ◽  
Mass Energy ◽  
Center Of Mass Energy ◽  
Lepton Colliders ◽  
The Standard Model

We discuss the physics opportunities and challenges presented by high energy lepton colliders in the range of center-of-mass energy between few and several tens of TeV. The focus is on the progress attainable on the study of weak and Higgs interactions in connection with new physics scenarios motivated by the shortcomings of the Standard Model.

scholarly journals Impact of $$b \rightarrow s \ell \ell $$ anomalies on rare charm decays in non-universal $$Z'$$ models

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
Ashutosh Kumar Alok ◽  
Neetu Raj Singh Chundawat ◽  
Dinesh Kumar
Keyword(s):  
New Physics ◽  
Tree Level ◽  
Long Distance ◽  
Charm Decays ◽  
Decay Modes ◽  
The Standard Model ◽  
Quark Level ◽  
Level Transition ◽  
The Impact ◽  
Rare Charm

AbstractIn this work, we study the impact of $$b \rightarrow s \ell \ell $$ b → s ℓ ℓ , $$B_s - \bar{B_s}$$ B s - B s ¯ mixing and neutrino trident measurements on observables in decays induced by $$c \rightarrow u $$ c → u transition in the context of a non-universal $$Z'$$ Z ′ model which generates $$C^{\mathrm{NP}}_{9} <0$$ C 9 NP < 0 and $$C^{\mathrm{NP}}_9 = - \,C^{\mathrm{NP}}_{10} $$ C 9 NP = - C 10 NP new physics scenarios at the tree level. We inspect the effects on $$D^0 \rightarrow \pi ^0 \nu {\bar{\nu }}$$ D 0 → π 0 ν ν ¯ , $$D^+ \rightarrow \pi ^+ \nu {\bar{\nu }}$$ D + → π + ν ν ¯ and $$B_c \rightarrow B^+ \nu {\bar{\nu }} $$ B c → B + ν ν ¯ decays which are induced by the quark level transition $$c \rightarrow u \nu {\bar{\nu }}$$ c → u ν ν ¯ . The fact that the branching ratios of these decays are negligible in the standard model (SM) and the long distance effects are relatively smaller in comparison to their charged dileptons counterparts, they are considered to provide genuine null-tests of SM. Therefore the observation of these modes at the level of current as well as planned experimental sensitivities would imply unambiguous signature of new physics. Using the constraints on $$Z'$$ Z ′ couplings coming from a combined fit to $$b \rightarrow s \ell \ell $$ b → s ℓ ℓ , $$\varDelta M_s$$ Δ M s and neutrino trident data, we find that any meaningful enhancement over the SM value is ruled out in the considered framework. The same is true for $$D - {\bar{D}}$$ D - D ¯ mixing observable $$\varDelta M_D$$ Δ M D along with $$D^0 \rightarrow \mu ^+ \mu ^-$$ D 0 → μ + μ - and $$D^+ \rightarrow \pi ^+ \mu ^+ \mu ^-$$ D + → π + μ + μ - decay modes which are induced through $$c \rightarrow u \mu ^+ \mu ^-$$ c → u μ + μ - transition.

scholarly journals Dark Photon Searches at BESIII

2018 ◽  
Vol 46 ◽  
pp. 1860046 ◽  
Author(s):  
Dayong Wang
Keyword(s):  
Degrees Of Freedom ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Gauge Bosons ◽  
Data Set ◽  
Decay Modes ◽  
Dark Photon ◽  
The Standard Model ◽  
New Type ◽  
Low Mass

Many models beyond the Standard Model, motivated by the recent astrophysical anomalies, predict a new type of weak-interacting degrees of freedom. Typical models include the possibility of the low-mass dark gauge bosons of a few GeV and thus making them accessible at the BESIII experiment running at the tau-charm region. The BESIII has recently searched such dark bosons in several decay modes using the high statistics data set collected at charmonium resonaces. This talk will summarize the recent BESIII results of these dark photon searches and related new physics studies.

scholarly journals Flavor physics: Precision as an avenue to discovery

2020 ◽  
Vol 35 (01) ◽  
pp. 1930018
Author(s):  
Diego Guadagnoli
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Flavor Physics ◽  
Standard Model Prediction ◽  
New Physics ◽  
Effective Theory ◽  
Theory Approach ◽  
Long Distance ◽  
The Standard Model ◽  
The Impact

This paper describes the work pursued in the years 2008–2013 on improving the Standard Model prediction of selected flavor-physics observables. The latter includes: (1) [Formula: see text], that quantifies indirect CP violation in the [Formula: see text] system and (2) the very rare decay [Formula: see text], recently measured at the LHC. Concerning point (1), the paper describes our reappraisal of the long-distance contributions to [Formula: see text],[Formula: see text] that have permitted to unveil a potential tension between CP violation in the [Formula: see text]- and [Formula: see text]-system. Concerning point (2), the paper gives a detailed account of various systematic effects pointed out in Ref. 4 and affecting the Standard Model [Formula: see text] decay rate at the level of 10% — hence large enough to be potentially misinterpreted as nonstandard physics, if not properly included. The paper further describes the multifaceted importance of the [Formula: see text] decays as new physics probes, for instance how they compare with [Formula: see text]-peak observables at LEP, following the effective-theory approach of Ref. 5. Both cases (1) and (2) offer clear examples in which the pursuit of precision in Standard Model predictions offered potential avenues to discovery. Finally, this paper describes the impact of the above results on the literature, and what is the further progress to be expected on these and related observables.

scholarly journals tt̄H Coupling Measurement with the ATLAS Detector at the LHC

2018 ◽  
Vol 182 ◽  
pp. 02052
Author(s):  
Asma Hadef
Keyword(s):  
Higgs Boson ◽  
Cross Sections ◽  
Top Quark ◽  
High Energy Physics ◽  
Center Of Mass ◽  
High Energy ◽  
New Physics ◽  
Decay Modes ◽  
Center Of Mass Energy ◽  
Higgs Decay

The Higgs boson was discovered on the 4th of July 2012 with a mass around 125 GeV by ATLAS and CMS experiments at LHC. Determining the Higgs properties (production and decay modes, couplings,...) is an important part of the high-energy physics programme in this decade. A search for the Higgs boson production in association with a top quark pair (tt̄H) at ATLAS [1] is summarized in this paper at an unexplored center-of-mass energy of 13 TeV, which could allow a first direct measurement of the top quark Yukawa coupling and could reveal new physics. The tt̄H analysis in ATLAS is divided into 3 channels according to the Higgs decay modes: H → Hadrons, H → Leptons and H → Photons. The best-fit value of the ratio of observed and Standard Model cross sections of tt̄H production process, using 2015-2016 data and combining all tt̄H final states, is 1:8±0:7, corresponds to 2:8σ (1:8σ) observed (expected) significance.

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 AFTER THE STANDARD MODEL: NEW RESONANCES AT THE LHC

2009 ◽  
Vol 24 (01) ◽  
pp. 1-15 ◽  
Author(s):  
GUSTAAF BROOIJMANS
Keyword(s):  
Large Hadron Collider ◽  
Standard Model ◽  
Hadron Collider ◽  
Center Of Mass ◽  
New Physics ◽  
Mass Energy ◽  
High Expectations ◽  
Center Of Mass Energy ◽  
Energy Regime ◽  
The Standard Model

Experiments will soon start taking data at CERN's Large Hadron Collider (LHC) with high expectations for discovery of new physics phenomena. Indeed, the LHC's unprecedented center-of-mass energy will allow the experiments to probe an energy regime where the standard model is known to break down. Here, the experiments' capability to observe new resonances in various channels is reviewed.

scholarly journals Searches for extra spatial dimensions with the CMS detector at the LHC

2015 ◽  
Vol 30 (15) ◽  
pp. 1540017 ◽  
Author(s):  
Greg Landsberg
Keyword(s):  
Hadron Collider ◽  
Center Of Mass ◽  
New Physics ◽  
Current Status ◽  
Beyond The Standard Model ◽  
Cern Large Hadron Collider ◽  
The Standard Model ◽  
Cms Detector ◽  
Spatial Dimensions ◽  
8 Tev

The success of the first three years of operations of the CERN Large Hadron Collider (LHC) at center-of-mass energies of 7 TeV and 8 TeV radically changed the landscape of searches for new physics beyond the Standard Model (BSM) and our very way of thinking about its possible origin and its hiding place. Among the paradigms of new physics that have been probed quite extensively at the LHC, are various models that predict the existence of extra spatial dimensions. In this review, the current status of searches for extra dimensions with the Compact Muon Solenoid (CMS) detector is presented, along with prospects for future searches at the full energy of the LHC, expected to be reached in the next few years.

scholarly journals Probing the Higgs with angular observables at future e+e− colliders

2016 ◽  
Vol 31 (33) ◽  
pp. 1644005 ◽  
Author(s):  
Zhen Liu
Keyword(s):  
Center Of Mass ◽  
Blind Spot ◽  
New Physics ◽  
Effective Field ◽  
Mass Energy ◽  
Center Of Mass Energy ◽  
Physics Potential ◽  
Energy Formula ◽  
Scalar Top ◽  
The Impact

I summarize our recent works on using differential observables to explore the physics potential of future [Formula: see text] colliders in the framework of Higgs effective field theory. This proceeding is based upon Refs. 1 and 2. We study angular observables in the [Formula: see text] channel at future circular [Formula: see text] colliders such as CEPC and FCC-ee. Taking into account the impact of realistic cut acceptance and detector effects, we forecast the precision of six angular asymmetries at CEPC (FCC-ee) with center-of-mass energy [Formula: see text] GeV and 5 (30) ab[Formula: see text] integrated luminosity. We then determine the projected sensitivity to a range of operators relevant for the Higgsstrahlung process in the dimension-6 Higgs EFT. Our results show that angular observables provide complementary sensitivity to rate measurements when constraining various tensor structures arising from new physics. We further find that angular asymmetries provide a novel means of constraining the “blind spot” in indirect limits on supersymmetric scalar top partners. We also discuss the possibility of using [Formula: see text]-fusion at [Formula: see text] machines at different energies to probe new operators.

scholarly journals ANOMALOUS HIGGS COUPLINGS

1999 ◽  
Vol 14 (20) ◽  
pp. 3121-3156 ◽  
Author(s):  
M. C. GONZALEZ-GARCIA
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Boson Production ◽  
Gauge Bosons ◽  
Effective Interactions ◽  
Decay Modes ◽  
Effective Lagrangian ◽  
The Standard Model

We review the effects of new effective interactions on Higgs-boson phenomenology. New physics in the electroweak bosonic sector is expected to induce additional interactions between the Higgs doublet field and the electroweak gauge bosons, leading to anomalous Higgs couplings as well as anomalous gauge-boson self-interactions. Using a linearly realized SU (2)L× U (1)Y invariant effective Lagrangian to describe the bosonic sector of the Standard Model, we review the effects of the new effective interactions on the Higgs-boson production rates and decay modes. We summarize the results from searches for the new Higgs signatures induced by the anomalous interactions in order to constrain the scale of new physics, in particular at CERN LEP and Fermilab Tevatron colliders.

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