ELECTROMAGNETIC EFFECTS AND THE LONG-STANDING THREE-NUCLEON ANALYZING POWER PUZZLE

2003 ◽  
Vol 18 (02n06) ◽  
pp. 258-261 ◽  
Author(s):  
W. TORNOW ◽  
E. M. NEIDEL ◽  
D. E. GONZÁLEZ TROTTER ◽  
C. R. HOWELL ◽  
A. S. CROWELL ◽  
...  

New results for the neutron-deuteron analyzing power Ay(θ) at En = 1.2 and 1.9 MeV and their comparison to proton-deuteron data reveal a sizeable and unexpected difference which increases with decreasing center-of-mass energy. This finding calls for the theoretical treatment of a subtle electromagnetic effect presently not incorporated in rigorous three-nucleon scattering calculations, before it is justified to invoke charge-dependent three-nucleon forces and/or other new physics.

Author(s):  
Roberto Franceschini

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.


2019 ◽  
Vol 214 ◽  
pp. 06006
Author(s):  
William Leight ◽  
Pierre-Francois Giraud ◽  
Peter Kluit ◽  
Jochen Meyer ◽  
Edward Moyse ◽  
...  

Muons with high momentum - above 500 GeV - are an important constituent of new physics signatures in many models. Run-2 of the LHC is greatly increasing ATLAS’s sensitivity to such signatures thanks to an ever-larger dataset of such particles, enhanced further by an increase in the center-of-mass energy. The ATLAS Muon Spectrometer chamber alignment contributes significantly to the uncertainty of the reconstruction of these high-momentum objects. The proper treatment of measurements during tracking and the correct propagation of the alignment effects is extremely challenging. Recently, an innovative approach that imposes Gaussian constraints on ensembles of detector hits was implemented. It provides a significant improvement to high-momentum tracking without increasing the CPU budget. Furthermore, it allows for the verification of the expected alignment quality using high-statistics collision data. A detailed discussion of the algorithmic realization is given, the expected performance gains are presented and prospects for further applications of the approach are outlined.


2009 ◽  
Vol 24 (01) ◽  
pp. 1-15 ◽  
Author(s):  
GUSTAAF BROOIJMANS

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.


2016 ◽  
Vol 31 (33) ◽  
pp. 1644005 ◽  
Author(s):  
Zhen Liu

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.


2020 ◽  
Vol 18 ◽  
pp. 66-77
Author(s):  
Abdeljali Habjial

The Standard Model production of four top quarks in the process pp --> tttt at a center-of-mass energy s1/2=13 Tev. The data collected by the ATLAS detector represents an impressive study potential, with an integrated luminosity of around 139 fb-1. In this manuscript, we present the production process of four top quarks at the LHC as well as some new physics models associated with this process. These models are studied in analysis carried. Some preliminary results are presented, in particular those of a new method for estimating background noise due to false leptons developed.


Universe ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 47 ◽  
Author(s):  
James Pinfold

MoEDAL is a pioneering LHC experiment designed to search for anomalously ionizing messengers of new physics. It started data taking at the LHC at a center-of-mass energy of 13 TeV, in 2015. Its ground breaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: Are there extra dimensions or new symmetries? What is the mechanism for the generation of mass? Does magnetic charge exist? What is the nature of dark matter? After a brief introduction, we report on MoEDAL’s progress to date, including our past, current and expected future physics output. We also discuss two new sub-detectors for MoEDAL: MAPP (Monopole Apparatus for Penetrating Particles) now being prototyped at IP8; and MALL (Monopole Apparatus for very Long Lived particles), currently in the planning stage. I conclude with a brief description of our program for LHC Run-3.


2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Rahul Basu ◽  
Tanumoy Mandal

We study central production, in the inclusive case, to look for graviton signals in a large extra dimensional model using dilepton and diphoton channels. We carefully analyze signal and possible standard model background processes and study the feasibility of such new physics searches in a relatively clean environment as in central production where the proton fragments are mostly emitted in the forward direction, and there is a clear rapidity gap between them and the centrally produced system. Our analysis shows that the LHC with 14 TeV center of mass energy and 100 fb−1(300 fb−1) of integrated luminosity can probe the effective gravity scale up to 3.6 TeV (4.4 TeV) in both the dilepton and diphoton channels.


2005 ◽  
Vol 20 (15) ◽  
pp. 3406-3408
Author(s):  
◽  
Richard Cavanaugh

In 2007, the Large Hadron Collider (LHC) will circulate and collide proton-proton beams at an expected center-of-mass energy of 14 TeV. The Compact Muon Solenoid (CMS) is one of four experiments at the LHC and has been designed with particular attention to selecting and reconstructing muons with high redundancy. This paper briefly describes the CMS Muon System and provides an overview of CMS preparations for new physics searches involving lepton final states during the early phases of running at the LHC.


2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
M. Köksal ◽  
V. Arı ◽  
A. Senol

The self-couplings of the electroweak gauge bosons are completely specified by the non-Abelian gauge nature of the Standard Model (SM). The direct study of these couplings provides a significant opportunity to test the validity of the SM and the existence of new physics beyond the SM up to the high energy scale. For this reason, we investigate the potential of the processes γγ→ZZ, e-γ→e-γ⁎γ→e-ZZ,  and e+e-→e+γ⁎γ⁎e-→e+ZZe- to examine the anomalous quartic couplings of ZZγγ vertex at the Compact Linear Collider (CLIC) with center-of-mass energy 3 TeV. We calculate 95% confidence level sensitivities on the dimension-8 parameters with various values of the integrated luminosity. We show that the best bounds on the anomalous fM2/Λ4, fM3/Λ4, fT0/Λ4, and fT9/Λ4 couplings arising from γγ→ZZ process among those three processes at center-of-mass energy of 3 TeV and integrated luminosity of Lint=2000 fb−1 are found to be [-3.30;3.30]×10-3 TeV−4, [-1.20;1.20]×10-2 TeV−4, [-3.40;3.40]×10-3 TeV−4, and [-1.80;1.80]×10-3 TeV−4, respectively.


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