Search results for "electroweak interaction"
showing 10 items of 358 documents
Simultaneous analysis of neutrinoless double beta decay and LHC pp-cross sections: limits on the left-right mixing angle
2015
The extension of the Standard Model of electroweak interactions, to accommodate massive neutrinos and/or right-handed currents, is one of the fundamental questions to answer in the cross-field of particle and nuclear physics. The consequences of such extensions would reflect upon nuclear decays, like the very exotic nuclear double-beta-decay, as well as upon high-energy proton-proton reactions of the type performed at the LHC accelerator. In this talk we shall address this question by looking at the results reported by the ATLAS and CMS collaborations, where the excitation and decay of a heavy-mass boson may be mediated by a heavy-mass neutrino in proton-proton reactions leading to two jets…
WIMPy baryogenesis with sterile neutrinos
2015
In this talk we propose a mechanism for baryogenesis from particle decays or annihilations that can work at the TeV scale. Some heavy particles annihilate or decay into a heavy sterile neutrino N (with M 1 TeV) and a "light" one ν (with m 100 GeV), generating an asymmetry among the two helicity degrees of freedom of v. This asymmetry is partially transferred to Standard Model leptons via fast Yukawa interactions and reprocessed into a baryon asymmetry by the electroweak sphalerons. We illustrate this mechanism in a WIMPy baryogenesis model where the helicity asymmetry is generated in the annihilation of dark matter. This model connects the baryon asymmetry, dark matter, and neutrino masses.
Group-Theoretic analysis of the mixing angle in the electroweak gauge group
1996
In this paper the authors provide strong mathematical support for the idea that the experimentally measured magnitude 1 - M{sub W}{sup 2}/M{sub Z}{sup 2} associated with sin{sup 2}{theta}{sub w} in the standard model of electroweak interactions cannot be simultaneously identified with the squared quotient of the electric charge by the SU(2) charge, e{sup 2}/g{sup 2}. In fact, the natural, mathematical requirement that the Weinberg rotation between the gauge fields associated with the third component of the {open_quotes}weak isospin{close_quotes} (T{sub 3}) and the hypercharge (Y) proceeds from a global Lie-group homomorphism of the SU(2) {circle_times} U(1){sub y} gauge group in some locall…
Weak Interactions at Low Energy
1985
In this series of lectures, I would like to discuss the basic aspects of the standard electroweak theory, as well as some alternatives. The phenomenology associated with charged and neutral currents weak interaction will show the success of the standard theory in giving a quantitative account of the existing data. The framework of most of our considerations will be that of an effective theory at low momentum transfer, low with respect to the masses of the intermediate vector bosons, 80–90 GeV. As an extension of the standard theory for the leptonic sector, I will contemplate the possibility of massive neutrinos being described by Majorana fields, leading to exotic phenomena induced by lepto…
Leptonic CP violation with massless neutrinos
1989
Abstract Leptonic CP violation may arise in the SU(2) ⊗ U(1) theory even if the neutrinos are strictly massless and, as a result, it is potentially large. Theoretical scenarios include isosinglet neutral heavy leptons which are present in many extensions of the standard electroweak theory such as superstring inspired models. We discuss in detail the nature of this CP violation and show that it can occur in a two-generation model. Possible effects are briefly discussed.
Shadowing in Inelastic Nucleon-Nucleon Cross Section?
2020
Experimental results of inclusive hard-process cross sections in heavy-ion collisions conventionally lean on a normalization computed from Glauber models where the inelastic nucleon-nucleon cross section $\sigma_{\rm nn}^{\rm inel}$ -- a crucial input parameter -- is simply taken from proton-proton measurements. In this letter, using the computed electro-weak boson production cross sections in lead-lead collisions as a benchmark, we determine $\sigma_{\rm nn}^{\rm inel}$ from the recent ATLAS data. We find a significantly suppressed $\sigma_{\rm nn}^{\rm inel}$ relative to what is usually assumed, show the consequences for the centrality dependence of the cross sections, and address the phe…
Search for an invisibly decaying Higgs boson in e+e-collisions at 189 GeV
1999
The data collected in 1998 by ALEPH at LEP at a centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 176.2 pb(-1), are analysed to search for invisible decays of a Higgs boson produced in the reaction e(+) e(-) --> hZ. The number of events found in the data and their properties art: in agreement with the Standard Model expectation. This search results in an improved 95% C.L. lower limit on the Higgs boson mass of 95.4 GeV/c(2), assuming it decays totally invisibly and for a production cross section equal to that of the Standard Model. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
Charge radius of the neutrino
2000
Using the pinch technique we construct at one-loop order a neutrino charge radius, which is finite, depends neither on the gauge-fixing parameter nor on the gauge-fixing scheme employed, and is process independent. This definition stems solely from an effective proper photon-neutrino one-loop vertex, with no reference to box or self-energy contributions. The role of the $\mathrm{WW}$ box in this construction is critically examined. In particular it is shown that the exclusion of the effective $\mathrm{WW}$ box from the definition of the neutrino charge radius is not a matter of convention but is in fact dynamically realized when the target fermions are right-handedly polarized. In this way …
pp→jje±μ±ννandjje±μ∓ννatO(αem6)andO(αem4αs2)for the study of the quartic electroweak gauge boson vertex at CERN LHC
2006
We analyze the potential of the CERN Large Hadron Collider (LHC) to study the structure of quartic vector-boson interactions through the pair production of electroweak gauge bosons via weak boson fusion $qq\ensuremath{\rightarrow}qqWW$. In order to study these couplings we have performed a partonic level calculation of all processes $pp\ensuremath{\rightarrow}jj{e}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\nu}\ensuremath{\nu}$ and $pp\ensuremath{\rightarrow}jj{e}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ensuremath{\mp}}\ensuremath{\nu}\ensuremath{\nu}$ at the LHC using the exact matrix elements at $\mathcal{O}({\ensuremath{\alpha}}…
Unifying left–right symmetry and 331 electroweak theories
2017
We propose a realistic theory based on the $\mathrm{SU(3)_c \otimes SU(3)_L \otimes SU(3)_R \otimes U(1)_{X}}$ gauge group which requires the number of families to match the number of colors. In the simplest realization neutrino masses arise from the canonical seesaw mechanism and their smallness correlates with the observed V-A nature of the weak force. Depending on the symmetry breaking path to the Standard Model one recovers either a left-right symmetric theory or one based on the $\mathrm{SU(3)_c \otimes SU(3)_L \otimes U(1)}$ symmetry as the "next" step towards new physics.