scholarly journals CP VIOLATION AND BEAUTY DECAYS — A CASE STUDY OF HIGH IMPACT, HIGH SENSITIVITY AND EVEN HIGH PRECISION PHYSICS

2000 ◽  
Vol 15 (08) ◽  
pp. 1079-1156
Author(s):  
I. I. BIGI

The narrative of these lectures contains three main threads: (i) CP violation despite having so far been observed only in the decays of neutral kaons has been recognized as a phenomenon of truly fundamental importance. The KM ansatz constitutes the minimal implementation of CP violation: without requiring unknown degrees of freedom it can reproduce the known CP phenomenology in a nontrivial way. (ii) The physics of beauty hadrons — in particular their weak decays — opens a novel window onto fundamental dynamics: they usher in a new quark family (presumably the last one); they allow us to determine fundamental quantities of the Standard Model like the b quark mass and the CKM parameters V(cb), V(ub), V(ts) and V(td); they exhibit speedy or even rapid [Formula: see text] oscillations. (iii) Heavy Quark Expansions allow us to treat B decays with an accuracy that would not have been thought possible a mere decade ago. These three threads are joined together in the following manner: (a) Huge CP asymmetries are predicted in B decays, which represents a decisive test of the KM paradigm for CP violation. (b) Some of these predictions are made with high parametric reliability, which (c) can be translated into numerical precision through the judicious employment of novel theoretical technologies. (d) Beauty decays thus provide us with a rich and promising field to search for New Physics and even study some of its salient features. At the end of it there might quite possibly be a New Paradigm for High Energy Physics. There will be some other threads woven into this tapestry: electric dipole moments, and CP violation in other strange and in charm decays.

2006 ◽  
Vol 21 (27) ◽  
pp. 5404-5415
Author(s):  
IKAROS I. BIGI

Detailed studies of weak charm decays fill an important future role in high energy physics. Chief among them are: (i) validating the theoretical control achieved over hadronization as a worthwhile goal in its own right; (ii) calibrating our tools to saturate the discovery potential for New Physics in B decays; (iii) searching for New Physics in charm decays through hypothesis-generating research. The most promising area for the last item is a comprehensive study of CP violation. Since we need a new CP paradigm to implement baryogenesis, this is not an idle goal. Charm decays provide opportunities unique among up-type quarks. While items (i) and (ii) will be addressed in a meaningful way and hopefully completed in the next few years, item (iii) will presumably require statistics that can be accumulated only by LHCb and a Super-B factory.


2004 ◽  
Vol 19 (31) ◽  
pp. 5463-5475 ◽  
Author(s):  
DAVID LONDON

I review CP violation in the standard model (SM). I also describe the predictions for CP violation in the B system, along with signals for physics beyond the SM. I stress the numerous contributions of Pat O'Donnell to this subject. Finally, I discuss a new method for measuring new-physics parameters in B decays. This knowledge will allow us to partially identify any new physics which is found, before its direct production at high-energy colliders.


Author(s):  
Gregor Kasieczka ◽  
Benjamin Nachman ◽  
David Shih ◽  
Oz Amram ◽  
Anders Andreassen ◽  
...  

Abstract A new paradigm for data-driven, model-agnostic new physics searches at colliders is emerging, and aims to leverage recent breakthroughs in anomaly detection and machine learning. In order to develop and benchmark new anomaly detection methods within this framework, it is essential to have standard datasets. To this end, we have created the LHC Olympics 2020, a community challenge accompanied by a set of simulated collider events. Participants in these Olympics have developed their methods using an R&D dataset and then tested them on black boxes: datasets with an unknown anomaly (or not). Methods made use of modern machine learning tools and were based on unsupervised learning (autoencoders, generative adversarial networks, normalizing flows), weakly supervised learning, and semi-supervised learning. This paper will review the LHC Olympics 2020 challenge, including an overview of the competition, a description of methods deployed in the competition, lessons learned from the experience, and implications for data analyses with future datasets as well as future colliders.


2018 ◽  
Vol 182 ◽  
pp. 02052
Author(s):  
Asma Hadef

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.


2007 ◽  
Vol 85 (6) ◽  
pp. 597-606
Author(s):  
A Ritz

We dicuss the utility of precision probes for flavour-diagonal CP-violation, namely, searches for electric dipole moments of nucleons, atoms, and molecules, in looking for new physics thresholds that manifest themselves primarily through higher dimensional operators. After reviewing the status of the electric dipole moment (EDM) constraints, we consider first the sensitivity to a generic class of dimension-five operators generated at a supersymmetric threshold, through their contribution to CP- and flavour-violating observables. Such thresholds can be probed by EDMs up to a scale of order 108 GeV depending on the flavour structure. We then turn to consider the possibility that electroweak baryogenesis is made feasible by the introduction of dimension-six operators at a TeV-scale threshold. The EDM costraints on dimension-six couplings of the Higgs to the fermions currently still allow a reasonable window in parameter space for these models, but the next generation of experiments should provide a conclusive test. PACS Nos.: 11.30.Er, 12.60.Fr, 12.60.Jv


1998 ◽  
Vol 13 (40) ◽  
pp. 3235-3249 ◽  
Author(s):  
S. I. BITYUKOV ◽  
N. V. KRASNIKOV

We propose a method to estimate the probability of new physics discovery in future high energy physics experiments. Physics simulation gives both the average numbers <Nb> of background and <Ns> of signal events. We find that the proper definition of the significance for <Nb>, <Ns> ≫ 1 is [Formula: see text] in comparison with often used significances: [Formula: see text] and [Formula: see text]. We propose a method of taking into account the systematical errors related to nonexact knowledge of background and signal cross-sections. An account of such systematics is essential in the search for supersymmetry at LHC. We also propose a method for estimating exclusion limits on new physics in future experiments.


2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
M. Köksal ◽  
A. A. Billur ◽  
A. Gutiérrez-Rodríguez

We obtain bounds on the anomalous magnetic and electric dipole moments of thet-quark from a future high-energy and high-luminosity linear electron positron collider, as the CLIC, with polarized and unpolarized electron beams which are powerful tools for determining new physics. We consider the processesγe-→t¯bνe(γis the Compton backscattering photon) ande+e-→e-γ⁎e+→t¯bνee+(γ⁎is the Weizsacker-Williams photon) as they are one of the most important sources of single top quark production. For systematic uncertainties ofδsys=0%  (5%),b-tagging  efficiency=0.8, center-of-mass energy ofs=3 TeV, and integrated luminosity ofL=2ab-1the futuree+e-collider may put bounds on the electromagnetic dipole momentsa^Vanda^Aof the top quark of the order ofO(10-2–10-1)at the2σ  (3σ)level, which are competitive with those recently reported in previous studies at hadron colliders and the ILC.


2007 ◽  
Vol 22 (30) ◽  
pp. 5433-5442
Author(s):  
R. J. BARLOW

New results on rare decays of B mesons and τ leptons are summarised. Measurement are generally in excellent agreement with the Standard Model predictions, the only exceptions being the polarisation of vector particles in B decays and the non-appearance of CP violation in B ± → K ±π0.


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