Search results for "DECAY"
showing 10 items of 2087 documents
Structure and prospects of the simplest SO(10) GUTs
2012
We recapitulate the latest results on the class of the simplest SO(10) grand unified models in which the GUT-scale symmetry breaking is triggered by an adjoint Higgs representation. We argue that the minimal survival approximation traditionally used in the GUT- and seesaw-scale estimates tends to be blind to very interesting parts of the parameter space in which some of the intermediate-scale states necessary for non-supersymmetric unification of the SM gauge couplings can be as light as to leave their imprints in the TeV domain. The stringent minimal-survival-based estimates of the B-L scale are shown to be relaxed by as much as four orders of magnitude, thus admitting for a consistent imp…
Kaon Tagging at 0° Scattering Angle for High-Resolution Decay-Pion Spectroscopy
2014
At the Mainz Microtron hypernuclei can be studied by (e,e'K) reactions. By detecting the kaon which is emitted in forward direction, with the KAOS spectrometer placed at 0 scattering angle, reactions involving open strangeness production are tagged. High-resolution magnetic spectrometers are then used to coincidentally detect the mono- energetic decay-pions from mesonic two-body weak decays of light hypernuclei at rest. As a pioneering experiment has confirmed, the KAOS spectrometer is exposed to a large flux of background particles, mostly positrons from bremsstrahlung pair production. In order to increase the e ciency of kaon identification the KAOS spectrometer was modi- fied to suppress…
Rare weak decays and nuclear structure
2014
Abstract. Weak interactions cause the atomic nuclei to decay via beta and double beta decays. Double beta decays are extremely rare since they are weak-interaction processes of the second order. Also (single) beta decays can be extremely rare. This can be caused by either a large di ff erence between the spins of the initial and final state (the so-called “forbidden” beta decays) or an extremely small Q value (decay energy) of the decay. All these cases are discussed in this article, and particular emphasis is given to the neutrino- less double electron capture on the double beta side of decays. peerReviewed
QED one-loop corrections to radiative muon decay
1994
Based upon the Fermi interaction, the differential decay rate of the radiative muon decay including one-loop radiative corrections is determined to the order ${G}_{F}^{2}{\ensuremath{\alpha}}^{2}$. Essential aspects of the calculation are exhibited. After cancellation of IR divergences, the double radiative muon decay is included. Some initial applications are considered.
Analysis of light neutrino exchange and short-range mechanisms in 0νββ decay
2020
Neutrinoless double beta decay (0νββ) is a crucial test for lepton number violation. Observation of this process would have fundamental implications for neutrino physics, theories beyond the Standard Model and cosmology. Focusing on so-called short-range operators of 0νββ and their potential interplay with the standard light Majorana neutrino exchange, we present the first complete calculation of the relevant nuclear matrix elements, performed within the interacting boson model (IBM-2). Furthermore, we calculate the relevant phase space factors using exact Dirac electron wave functions, taking into account the finite nuclear size and screening by the electron cloud. The obtained numerical r…
Towards a New Minimal SO(10) Unification
2012
We argue that non-supersymmetric SO(10) models based on a renormalizable Higgs sector in which spontaneous symmetry breaking is triggered by the VEVs of a 45-dimensional adjoint and a 126-dimensional tensor representations can provide a potentially realistic yet relatively simple framework for a future robust estimate of the proton lifetime. Following closely the work Phys.Rev.D85, 095014 (2012), arXiv: 1202.0807 [hep-ph] we comment on the gauge unification constraints on the B-L breaking scale and show that there are several regions in the parameter space of the minimal model where the seesaw scale in the phenomenologically favoured ballpark of around 10^13-14 GeV is consistently supported.
Limit on theB0→ρ0ρ0Branching Fraction and Implications for the Cabibbo-Kobayashi-Maskawa Angleα
2005
The authors search for the decay B{sup 0} {yields} {rho}{sup 0}{rho}{sup 0} in a data sample of about 227 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. They find no significant signal and set an upper limit of 1.1 x 10{sup -6} at 90% CL on the branching fraction. As a result, the uncertainty due to penguin contributions on the CKM unitarity angle {alpha} measured in B {yields} {rho}{rho} decays is 11{sup o} at 68% CL.
Measurements ofCP-Violating Asymmetries inB0→Ks0π0Decays
2007
The authors present measurements of CP-violating asymmetries in the decay B{sup 0} {yields} a{sub 1}{sup {+-}}(1260){pi}{sup {-+}} with a{sub 1}{sup {+-}}(1260) {yields} {pi}{sup {-+}}{pi}{sup {+-}}{pi}{sup {+-}}. The data sample corresponds to 384 x 10{sup 6} B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric B-factory at SLAC. They measure the CP-violating asymmetry {Alpha}{sub CP}{sup a{sub 1}{pi}} = -0.07 {+-} 0.07 {+-} 0.02, the mixing-induced CP violation parameter S{sub a{sub 1}{pi}} = 0.37 {+-} 0.21 {+-} 0.07, the direct Cp violation parameter C{sub a{sub 1}{pi}} = -0.10 {+-} 0.15 {+-} 0.09, and the parameters {Delta}C{sub a{sub 1}{pi}} = 0.26 {+-} 0.15 {+-} 0…
On the corner elements of the CKM and PMNS matrices
2013
Recent experiments show that the top-right corner element (U-e3) of the PMNS matrix is small but nonzero, and suggest further via unitarity that it is smaller than the bottom-left corner element (U-tau 1). Here, it is shown that if to the assumption of a universal rank-one mass matrix, long favoured by phenomenologists, one adds that this matrix rotates with scale, then it follows that A) by inputting the mass ratios m(c)/m(t), m(s)/m(b), m(mu)/m(tau), and m(2)/m(3), i) the corner elements are small but nonzero, ii) V-ub < V-td, U-e3 < U-tau 1, iii) estimates result for the ratios V-ub/V-td and U-e3/U-tau 1, and B) by inputting further the experimental values of V-us, V-tb and U-e2, U-mu 3,…
Observation of the Baryonic Flavor-Changing Neutral Current Decay Λb0→Λμ+μ-
2011
8 páginas, 2 figuras, 4 tablas.-- PACS numbers: 13.30.Ce, 12.15.Mm, 14.20.Mr.-- CDF Collaboration: et al.