77 results on '"*DECAY schemes (Radioactivity)"'
Search Results
2. Time-resolved photoluminescence of barium titanate ultrafine powders.
- Author
-
Lu, S. G., Xu, Z. K., Chen, Haydn, Mak, C. L., Wong, K. H., Li, K. F., and Cheah, K. W.
- Subjects
- *
PHOTOLUMINESCENCE , *CHEMICAL decomposition , *DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) , *NUCLEAR physics , *ELECTRONS - Abstract
Time-resolved photoluminescence (PL) near 540 nm, taken from barium titanate (BaTiO3) ultrafine powders of ∼80, 90, and 110 nm in size, was measured at 11 K. Two-exponential functions were found to fit the decay curves well, and the decay lifetimes were composed of one short, about 10 ns, and one long, about 200 ns, time constants, respectively. Results also indicate that the PL peaks show a small blueshift with decreasing BaTiO3 particle size. The decay process consists of the recombination of self-trapped excitons (long lifetime decay) and of the electrons in the surface states with the holes in the valence band (short lifetime decay). The short lifetime component makes comparable contribution to the decay intensity of PL with the long lifetime one. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
3. Leptogenesis in Higgs triplet model.
- Author
-
Scopel, Stefano
- Subjects
- *
LEPTONS (Nuclear physics) , *PHENOMENOLOGICAL theory (Physics) , *NEUTRINO mass , *TRANSPORT theory , *SUPERSYMMETRY , *DECAY schemes (Radioactivity) - Abstract
We analyze leptogenesis in a supersymmetric triplet seesaw scenario that explains at the same time the baryon asymmetry in the Universe and the observed neutrino masses. First, we adopt a phenomenological approach where, in order to single out the main features of the model, the decay branching ratios of the triplets and the amount of CP-violation in their different decay channels are assumed as free parameters. We then consider the particular example of soft leptogenesis, which employs a non-vanishing phase and a resonant behavior in the supersymmetry breaking sector to generate CP violation. In both scenarios we solve the relevant Boltzman equations and show that gauge annihilation processes may strongly suppress the resulting lepton asymmetry. In particular we find that soft leptogenesis is successful only for a triplet mass at the TeV scale, opening up an interesting opportunity for testing the model in future colliders. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
4. Rare Decays of Tau Leptons: an Experimental Review.
- Author
-
Urheim, Jon
- Subjects
- *
LEPTONS (Nuclear physics) , *RADIOACTIVE decay , *DECAY schemes (Radioactivity) , *NUCLEAR reactions , *NUCLEAR physics , *PHYSICS - Abstract
I review the current experimental situation with regard to searches for rare decays of τ leptons. The recent progress in this area has been made by the BELLE and BaBar collaborations thanks to their impressive datasets and detection capabilities, attention to backgrounds, and careful statistical treatments of the data. After summarizing the present status, the review concludes with look at the future prospects for these searches. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
5. Search for the Lepton-Flavor-Violating Decays Bs0→e±μ∓ and B0→e±μ∓.
- Author
-
Aaij, R., Adeva, B., Adinolfi, M., Adrover, C., Affolder, A., Ajaltouni, Z., Albrecht, J., Alessio, F., Alexander, M., Ali, S., Alkhazov, G., Alvarez Cartelle, P., Alves, Jr., A. A., Amato, S., Amerio, S., Amhis, Y., Anderlini, L., Anderson, J., Andreassen, R., and Andrews, J. E.
- Subjects
- *
LEPTONS (Nuclear physics) , *PARTICLE decays , *DECAY schemes (Radioactivity) , *LUMINOSITY , *LEPTOQUARKS , *PARTICLES (Nuclear physics) - Abstract
A search for the lepton-flavor-violating decays B0s → e± μ± and B0 → e± μ± is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions at √s = 7 TeV, collected by the LHCb experiment. The observed number of B0s → e± μ± and B0 → e± μ± candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(B0s → e± μ±) < 1.1(1.4) x 10-8 and B(B0 → e± μ± ) <2.8(3.7) X 10-9 at 90% (95%) confidence level (C.L.). These limits are a factor of 20 lower than those set by previous experiments. Lower bounds on the Pati-Salam leptoquark masses are also calculated, MLQ(B0s → e± μ±)> 101 TeV/c2 and MLQ(B0s → e± μ±)> 126 TeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
6. Status of the measurement of KS → πe? branching ratio and lepton charge asymmetry with the KLOE detector.
- Author
-
Kamińska, Daria
- Subjects
- *
LEPTONS (Nuclear physics) , *PARTICLE decays , *BRANCHING ratios , *DECAY schemes (Radioactivity) , *NUCLEAR physics , *NUCLEAR science - Abstract
We present the current status of the analysis of about 1.7 billion KS KL pair events collected at DAΦNE with the KLOE detector to determine the branching ratio of KS → πev decay and the lepton charge asymmetry. This sample is ~ 4 times larger in statistics than the one used in the previous most precise result, from KLOE as well, allowing us to improve the accuracy on the measurement and related tests of CPT symmetry and ΔS = ΔQ rule. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
7. Search for the rare decays and
- Author
-
Aaij, R., Adeva, B., Adinolfi, M., Adrover, C., Affolder, A., Ajaltouni, Z., Albrecht, J., Alessio, F., Alexander, M., Alvarez Cartelle, P., Alves, A.A., Amato, S., Amhis, Y., Amoraal, J., Anderson, J., Appleby, R.B., Aquines Gutierrez, O., Arrabito, L., Artuso, M., and Aslanides, E.
- Subjects
- *
DECAY schemes (Radioactivity) , *PROTON-proton interactions , *LARGE Hadron Collider , *BRANCHING ratios , *CONFIDENCE intervals , *PARTICLE decays , *LEPTONS (Nuclear physics) - Abstract
Abstract: A search for the decays and is performed with about of pp collisions at collected by the LHCb experiment at the Large Hadron Collider at CERN. The observed numbers of events are consistent with the background expectations. The resulting upper limits on the branching ratios are and at 95% confidence level. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
8. Performance of the liquid xenon detector for the MEG experiment
- Author
-
Nishimura, Yasuhiro and Natori, Hiroaki
- Subjects
- *
XENON , *DETECTORS , *CALIBRATION , *PHOTONS , *PHYSICS experiments , *DECAY schemes (Radioactivity) , *SCINTILLATORS , *CP violation , *LEPTONS (Nuclear physics) , *FLAVOR in particle physics - Abstract
Abstract: A 900-l liquid xenon (LXe) detector was constructed for the MEG experiment to look for . With proper calibration and monitoring the detector was successfully operated during the first physics data taking for three months in 2008. We evaluated the performance of the LXe detector around the energy of 52.8MeV by using 54.9-MeV photons obtained from decays. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
9. σ and substructures from , radiative and semi-leptonic decays
- Author
-
Mennessier, G., Narison, S., and Wang, X.-G.
- Subjects
- *
QUANTUM chromodynamics , *LEPTONS (Nuclear physics) , *PARTICLE decays , *RADIOACTIVE decay , *SCATTERING (Physics) , *QUARKS , *GLUONS , *MESONS , *DISPERSION relations , *SUM rules (Physics) , *DECAY schemes (Radioactivity) , *SIGMA particles - Abstract
Abstract: Using an improved “analytic K-matrix model”, we reconsider the extraction of the and γγ widths from scatterings data of Crystal Ball and Belle. Our main results are summarized in Tables 3 and 4. The averaged σ “direct width” to γγ is 0.16(3) keV which confirms a previous result of Mennessier et al. (2007, 2008) and which does neither favour a large four-quark/molecule nor a pure components. The “direct width” of the of 0.28(2) keV is much larger than the four-quark expectation but can be compatible with a or a gluonium component. We also found that the rescattering part of each amplitude is relatively large indicating an important contribution of the meson loops in the determinations of the σ and γγ total widths. This is mainly due to the large couplings of the σ and to ππ and/or , which can also be due to a light scalar gluonium with large OZI violating couplings but not necessary to a four-quark or molecule state. Our average results for the total (direct + rescattering) γγ widths: , are comparable with the ones from dispersion relations and PDG values. Using the parameters from QCD spectral sum rules, we complete our analysis by showing that the production rates of unmixed scalar gluonia and agree with the data from , ϕ radiative and semi-leptonic decays. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
10. FCNC PROCESSES IN THE LITTLEST HIGGS MODEL WITH T-PARITY: AN UPDATE.
- Author
-
Blanke, Monika, Buras, Andrzej J., Duling, Björn, Recksiegel, Stefan, and Tarantino, Cecilia
- Subjects
- *
HIGGS bosons , *LOGARITHMS , *ULTRAVIOLET radiation , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
We update our 2006-2007 results for FCNC processes in the Littlest Higgs model with T-parity (LHT). The removal of the logarithmic UV cutoff dependence in our previous results through a new contribution to the Z0-penguin diagrams identified by Goto et al. and del Aguila et al., while making the deviations from the SM expectations in the quark sector less spectacular, still allows for sizable new physics effects in K → πνν and KL → π0l+l- decays and in the CP-asymmetry Sψφ with the latter unaffected by the new contribution. We extend our analysis by a study of the fine-tuning required to fit the data on εK and by the inclusion of the decay KL → μ+&mu-. A number of correlations can distinguish this model from the custodially protected Randall--Sundrum model analysed recently. We also reconsider lepton flavour violating decays, including now a discussion of fine-tuning. While the li → ljγ decays are unaffected by the removal of the logarithmic cutoff dependence, the branching ratios for decays with three leptons in the final state, like μ → 3e are lowered by almost an order of magnitude. In spite of this, the pattern of lepton flavour violation in the LHT model can still be distinguished from the one in supersymmetric models. [ABSTRACT FROM AUTHOR]
- Published
- 2010
11. QCD AND HQET APPROACHES FOR ANALYSIS OF THE Bc π D0lv TRANSITION.
- Author
-
Ghahramany, N. and Khosravi, R.
- Subjects
- *
LEPTONS (Nuclear physics) , *GLUONS , *QUARKS , *DECAY schemes (Radioactivity) , *STATISTICAL correlation - Abstract
The form factors of the semileptonic Bc → D0lυ transition with l = e; τ are calculated in the framework of the three point QCD sum rules. In this case, the two gluon condensate contributions as the important correction on the non-perturbative part of the correlation function, are taken into account. The heavy quark effective theory limits of the form factors are also computed. The branching fractions of these decays are also evaluated and compared with the predictions of the other non-perturbative approaches. [ABSTRACT FROM AUTHOR]
- Published
- 2010
12. Tau sleptons and tau sneutrino decays in MSSM under the cosmological bounds.
- Author
-
SELBUZ, Levent and AYDIN, Z. Zekeriya
- Subjects
- *
LEPTONS (Nuclear physics) , *FERMIONS , *STANDARD model (Nuclear physics) , *DECAY schemes (Radioactivity) , *BRANCHING ratios - Abstract
We present a numerical investigation of the fermionic two-body decays of tau sleptons τ͂1,2 and τ sneutrino in the Minimal Supersymmetric Standard Model with complex parameters. In the analysis we particularly take into account the cosmological bounds imposed by WMAP data. We plot the CP-phase dependences for each fermionic two-body channel of τ͂1,2 and τ sneutrino and speculate about the branching ratios and total (two-body) decay widths. We find that the phase dependences of the decay widths of the third family sleptons are quite significant which can provide viable probes of additional CP sources. We also draw attention to the polarization of the final-state tau in the τ͂1,2 decays. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
13. Angular distribution of leptons from the decay of massive vector bosons
- Author
-
Berger, Edmond L., Qiu, Jian-Wei, and Rodriguez-Pedraza, Ricardo A.
- Subjects
- *
TRANSVERSE Mercator projection (Cartography) , *LEPTONS (Nuclear physics) , *BOSONS , *DECAY schemes (Radioactivity) - Abstract
Abstract: We examine the transverse momentum dependence of the helicity structure functions for massive vector bosons of mass Q in hadron reactions. We demonstrate that large logarithmic terms of the form in the helicity structure functions have the same origin as the logarithmic terms in the angular-integrated cross section and that they can be resummed to all orders in the strong coupling , in the same way as the angular-integrated cross section. As a consequence of current conservation, the resummed part of the helicity structure functions preserves the Lam–Tung relation as a function of to all orders in . [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
14. Rare t-quark decays t → cl l and t → cṽ j v k induced by doublets of scalar leptoquarks within the minimal four-color-symmetry model.
- Author
-
Popov, P. Yu. and Smirnov, A. D.
- Subjects
- *
DECAY schemes (Radioactivity) , *SCALAR field theory , *NEUTRINO mass , *INTERACTING boson-fermion models , *COUPLING constants , *PARTICLE decays , *LEPTONS (Nuclear physics) - Abstract
The rare t-quark decays t → cl l and t → cṽ j k k induced by scalar-leptoquark doublets are considered within the minimal model involving four-color quark-lepton symmetry and the Higgs mechanism of quark and lepton mass splitting. The partial widths with respect to the decays being considered and the total widths Γ( t → cl +′ l −) = Σj,k Γ( t → cl l ) and Γ( t → cl +′ l −) = Σj,kΓ( t → cṽ j v k ) with respect to, respectively, the charged leptonic and neutrino modes are calculated. It is shown that, at scalar-leptoquark masses higher than the t-quark mass ( m S > m t), the branching ratios for these modes are Br( t → cl +′ l −) ≈ (3.5−0.4) × 10−5 and Br( t → cṽ′ v) ≈ (7.1−0.8) × 10−5 at m s = 180–250 GeV and an appropriate value of the leptoquark-mixing angle (sin β ≈ 0.2) and can increase for m S < m t to Br( t → cl +′ l −) ≈ 0.03−0.002 and Br( t → cl +′ l −) ≈ 0.46−0.05 for the charged mode at m S = 150–170 GeV for sin β ≈ 1 and sin β ≈ 0.2, respectively. In the cases being considered, t-quark decays to pairs of charged leptons can be accessible to detection at LHC. In the last case, these decays could manifest themselves (for example, in dilepton events) at the Tevatron as well. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
15. LEPTONIC DECAYS OF VECTOR MESONS.
- Author
-
Bhatnagar, Shashank
- Subjects
- *
LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *MESONS , *VECTOR fields , *LORENTZ transformations , *ANALYSIS of covariance , *PARTICLES (Nuclear physics) - Abstract
In this paper, the general structure of leptonic decay constants of vector mesons is evaluated in the framework of the Bethe–Salpeter equation under the Covariant Instantaneous Ansatz (CIA), which is a Lorentz-invariant generalization of Instantaneous Approximation (IA). The numerical values of fV in this CIA framework are on the low side in comparison to recent calculations of these quantities. However, the overall asymptotic behavior of fV is in conformity with QCD predictions. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
16. CDF MEASUREMENT OF THE TOP QUARK MASS IN THE LEPTON+JETS CHANNEL USING THE MULTIVARIATE TEMPLATE METHOD.
- Author
-
FREEMAN, JOHN
- Subjects
- *
QUARKS , *PARTICLES (Nuclear physics) , *DECAY schemes (Radioactivity) , *RADIOACTIVE decay , *LEPTONS (Nuclear physics) , *NUCLEAR physics - Abstract
We measure the mass of the top quark using 162 pb-1 of data collected by the CDF experiment at the Fermilab Tevatron in Run II. The decay chain $t{\bar t} \to bq{\bar q}{\bar b}l\nu$ is studied using a novel technique called the Multivariate Template Method (MTM). Using this technique we obtain a result of $M_{top} = 179.6^{+6.4}_{-6.3}({\rm stat.}) \pm 6.8({\rm syst.})\ {\rm GeV}/c^2$ for the top quark. [ABSTRACT FROM AUTHOR]
- Published
- 2005
17. MEASUREMENT OF B(t→Wb)/B(t→Wq).
- Author
-
TECCHIO, MONICA
- Subjects
- *
QUARKS , *DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) , *PARTICLES (Nuclear physics) , *DILEPTON production , *STANDARD model (Nuclear physics) , *NUCLEAR physics - Abstract
We measure the ratio R = B(t→Wb)/B(t→Wq) in top-quark decays at CDF. R is determined from the relative rates of identified b jets in $t{\bar t}$ decays reconstructed both in the lepton-plus-jets and dilepton final states. We obtain R>0.62 at the 95% CL, consistent with Standard Model expectations. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
18. Polarized forward-backward asymmetries of leptonsindecay.
- Author
-
Aliev, T., Bashiry, V., and Savci, M.
- Subjects
- *
LEPTONS (Nuclear physics) , *PARTICLES (Nuclear physics) , *NUCLEAR physics , *DECAY schemes (Radioactivity) , *ENERGY levels (Quantum mechanics) - Abstract
Polarized forward-backward asymmetries in thedecay are calculated using the most general, model independent form of the effective Hamiltonian, including all possible forms of interactions. The dependencies of the asymmetries on new Wilson coefficients are investigated. The detectability of the asymmetries at LHC is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
19. The Lorentz and CPT violating effects on thedecay.
- Author
-
Iltan, E.
- Subjects
- *
LORENTZ transformations , *BRANCHING ratios , *SYMMETRICAL components (Electric engineering) , *SPECIAL relativity (Physics) , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *LOW energy electron diffraction , *ENERGY levels (Quantum mechanics) - Abstract
We study the Lorentz andCPTviolating effects on the branching ratio, theCPTviolating asymmetry and the ratio of the decay width, including only the Lorentz violating effects, to the one obtained in the standard model, for the flavor dependent part of the lepton flavor conserving() decay. The inclusion of the Lorentz andCPTviolating effects in the standard model contribution are too small to be detected, since the corresponding coefficients are highly suppressed at the low energy scale. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
20. Dosimetry Calculations on a Tissue Level by Using the MCNP4c2 Monte Carlo Code.
- Author
-
Erik Larsson, Bo-Anders Jnsson, Lena Jnsson, Michael Ljungberg, and Sven-Erik Strand
- Subjects
- *
DRUG dosage , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *RADIOACTIVE decay - Abstract
Objective: The aim of this study was to develop a MCNP4c2-code and to further refine the small-scale anatomy intestinal dosimetry model based on a EGS4-code developed by Jnsson et al.1,2Method: The small intestine was modeled as a hexagonal tube system and includes cross-dose contribution from activity in nearby intestine loops. The model includes villi (height, 500 m), radiosensitive crypt cells (height, 150 m), and an overlying mucus layer of thicknesses (5200 m). The developed intestinal model used in either of the two Monte Carlo codes make it possible to calculate S-values and subsequent mean absorbed dose to the radiation-sensitive crypt cells in the small intestinal wall by considering contributions from the self-dose and from the cross-dose from nearby intestinal loops. Results are given for monoenergetic electrons and photons and for full decay schemes of 99mTc, 111In, 131I, 67Ga, 90Y, and 211At. Results: Results show that the cross-dose from nearby intestinal loops is significant, and that the fraction of cumulated activity in the intestinal wall contents is important for accurate absorbed-dose estimation. Conclusion: It is evident from our study that previous Medical Internal Radiation Dose (MIRD) and International Conference on Radiological Protection (ICRP) models tend to overestimate the absorbed dose to the wall. Our work on the gastrointestinal tract model includes several noticeable refinements, as compared to the MIRD- and ICRP model, and the "onion shell" geometry can easily be transferred to similar geometrical dosimetry applications. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
21. Running neutrino masses, mixings and CP phases: analytical results and phenomenological consequences
- Author
-
Antusch, Stefan, Kersten, Jörn, Lindner, Manfred, and Ratz, Michael
- Subjects
- *
NEUTRINOS , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *RADIOACTIVITY - Abstract
We derive simple analytical formulae for the renormalization group running of neutrino masses, leptonic mixing angles and CP phases, which allow an easy understanding of the running. Particularly for a small angle
θ13 the expressions become very compact, even when non-vanishing CP phases are present. Using these equations we investigate: (i) the influence of Dirac and Majorana phases on the evolution of all parameters, (ii) the implications of running neutrino parameters for leptogenesis, (iii) changes of the mass bounds from WMAP and neutrinoless doubleβ decay experiments, relevant for high-energy mass models, (iv) the size of radiative corrections toθ13 andθ23 and implications for future precision measurements. [Copyright &y& Elsevier]- Published
- 2003
- Full Text
- View/download PDF
22. Subleading light-cone distribution functions in the decays <f>Λb→Xsγ</f> and <f>Λb→Xuℓν¯ℓ</f>
- Author
-
Kraetz, Michael and Mannel, Thomas
- Subjects
- *
LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
In this Letter we investigate the subleading twist corrections to the photon energy spectrum in the decay
Λb→Xsγ and to the lepton energy spectrum inΛb→Xuℓν¯ℓ . As a first step we rederive the matching coefficients of the subleading twist using a much simpler method. Parametrizing the matrix elements forΛb and using reparametrization invariance, we show that the energy spectra close to the endpoints are given in terms of only a single universal function. [Copyright &y& Elsevier]- Published
- 2003
- Full Text
- View/download PDF
23. Non-Factorizable Terms, Heavy Quark Masses, and Semileptonic Decays of D and B Mesons.
- Author
-
Voloshin, M. B.
- Subjects
- *
LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *QUARKS - Abstract
The non-factorizable terms in the operator product expansion have been recognized as one of the theoretical obstacles for precision determination of the mixing parameter V[sub ub] from semileptonic B decays. It is pointed out here that the recent CLEO data on the parameters of the heavy quark expansion λ[sub 1] and &Λmacr;, combined with a theoretical bound on λ[sub 1] strongly favor the existence of a sizeable contribution of non-factorizable terms in semileptonic decays of D mesons. Thus these terms are likely to solve the long-standing problem of the deficit of semileptonic decay rate of the D mesons, and with better data their magnitude can be determined and used in studies of the parameter V[sub ub]. [ABSTRACT FROM AUTHOR]
- Published
- 2002
- Full Text
- View/download PDF
24. Heavy neutrino searches at the LHC with displaced vertices.
- Author
-
Helo, J. C., Kovalenko, S. G., and Hirsch, M.
- Subjects
- *
NEUTRINOS , *STANDARD model (Nuclear physics) , *VERTEX detectors , *LARGE Hadron Collider , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
Sterile neutrinos with masses in the range of 1-100 GeV have been searched for in a variety of experiments. Here, we discuss the prospects of searching for sterile neutrinos at the LHC using displaced vertices. Two different cases are discussed: (i) the standard model extended with sterile neutrinos, and (ii) right-handed neutrinos in a left-right symmetric extension of the standard model. A dedicated displaced vertex search will allow us to probe parts of the parameter space not accessible to other searches, but both cases will require a large luminosity. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
25. Kaon Weak Decays in Chiral Theories.
- Author
-
Scadron, M. D.
- Subjects
- *
DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) , *LINEAR statistical models - Abstract
The ten nonleptonic weak decays K→2π, K→ 3π, K[sub L]→2γ, K[sub S]→2γ, K[sub L]→π[sup 0]2γ, are predicted for a chiral pole model based on the linear sigma model theory which automatically satisfies the partial conservation of axial current (PCAC) hypothesis. These predictions, agreeing with data to the 5% level and containing no or at most one free parameter, are compared with the results of chiral perturbation theory (ChPT). The latter ChPT approach to one-loop level is known to contain at least four free parameters and then predicts a K[sub L]→π[sup 0]γγ rate which is 60% shy of the experimental value. [ABSTRACT FROM AUTHOR]
- Published
- 1999
- Full Text
- View/download PDF
26. Test of lepton universality and search for lepton flavor violation in Υ(1S,2S,3S) decays at CLEO.
- Author
-
Dankó, István
- Subjects
- *
LEPTONS (Nuclear physics) , *PARTICLES (Nuclear physics) , *DECAY schemes (Radioactivity) , *BRANCHING ratios , *PHYSICS - Abstract
We present the analysis technique and preliminary results of two ongoing analyses at CLEO which put lepton universality and lepton flavor conservation to the test in Υ decays. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
27. Probing 3-3-1 models in diphoton Higgs boson decay.
- Author
-
Alves, A., Ramirez Barreto, E., Dias, A. G., De S. Pires, C. A., Queiroz, F. S., and Rodrigues da Silva, P. S.
- Subjects
- *
HIGGS bosons , *LARGE Hadron Collider , *LEPTONS (Nuclear physics) , *STANDARD model (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
We investigate the Higgs boson production through gluon fusion and its decay into two photons at the LHC in the context of the minimal 3-3-1 model and its alternative version with exotic leptons. The diphoton Higgs decay channel presents an enhanced signal in this model compared to the standard model due to the presence of an extra singly charged vector boson and a doubly charged one. Prospects for the Higgs boson detection at 7 TeV center-of-mass energy with up to 10 fb-1 are presented. Our results suggest that a Higgs boson from these 3-3-1 models can potentially explain the small excess for mH ≤ 145 GeV observed at the LHC. Otherwise, if this excess reveals to be only a statistical fluctuation of the standard model backgrounds, severe constraints can be put on these models. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
28. Randall-Sundrum corrections to the width difference and CP-violating phase in…-meson decays.
- Author
-
Goertz, Florian and Pfoh, Torsten
- Subjects
- *
DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) , *OPERATOR theory , *CP violation ,MESON decay - Abstract
We study the impact of the Randall-Sundrum setup on the width difference ΔΓs and the CP-violating phase φs in the Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed system. Our calculations are performed in the general framework of an effective theory, based on operator product expansion. The results can thus be used for many new-physics models. We find that the correction to the magnitude of the decay amplitude Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed is below 4% for a realistic choice of input parameters. The main modification in the ΔΓs/βs-plane is caused by a new CP-violating phase in the mixing amplitude, which allows for a better agreement with the experimental results of the CDF and D0 Collaborations from Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed decays. The best-fit value of the CP asymmetry Sψψ can be reproduced, while simultaneously the theoretical prediction for the semileptonic CP asymmetry Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed can enter the 1σ range. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
29. Semileptonic… (1968) decays as a scalar meson probe.
- Author
-
Fariborz, Amir H., Jora, Renata, Schechter, Joseph, and Shahid, M. Naeem
- Subjects
- *
LEPTONS (Nuclear physics) , *PARTICLE decays , *DECAY schemes (Radioactivity) , *MESONS , *HADRON decay , *ROTATIONAL motion - Abstract
The unusual multiplet structures associated with the light spin zero mesons have recently attracted a good deal of theoretical attention. Here we discuss some aspects associated with the possibility of getting new experimental information on this topic from semileptonic decays of heavy charged mesons into an isosinglet scalar or pseudoscalar plus leptons. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
30. Exotic seesaw-motivated heavy leptons at the LHC.
- Author
-
Kumerički, Krešimir, Picek, Ivica, and Radovčić, Branimir
- Subjects
- *
LARGE Hadron Collider , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *LUMINOSITY distance , *NEUTRINOS - Abstract
We study the LHC potential for discovering TeV-scale SU(2)L 5-plet fermions introduced recently to explain small neutrino masses. We show that the Drell-Yan production and the decays of new exotic Σ leptons are testable at the LHC. Their production is abundant due to nontrivial electroweak gauge charges. For 1 fb-1 of integrated luminosity at the present LHC √s = 7 TeV, there can be 270 Σ - Σ̄ pairs produced for MΣ = 400 GeV. Besides producing same-sign dilepton events, they could lead, due to a chosen small mixing between heavy and light leptons, to ~10 golden decays Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed with a specific decay signature. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
31. Higgs boson finder and mass estimator: The Higgs boson to WW to leptons decay channel at the LHC.
- Author
-
Barger, Vernon and Peisi Huang
- Subjects
- *
HIGGS bosons , *LARGE Hadron Collider , *ROTATIONAL motion , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
We exploit the spin and kinematic correlations in the decay of a scalar boson into a pair of real or virtual W-bosons, with both W-bosons decaying leptonically, for Higgs boson discovery at 7 TeV LHC energy with 10 fb-1 luminosity. Without reconstruction of the events, we obtain estimators of the Higgs mass from the peak and width of the signal distribution in mu. The separation of signal and background with other distributions, such as the azimuthal angle between two W decay planes, the rapidity difference between the two leptons, missing ET, and the pT of leptons, are also prescribed. Our approach identifies the salient Higgs to dilepton signatures that allow subtraction of the continuum W * W* background. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
32. Consequences of neutrino Lorentz violation for leptonic meson decays.
- Author
-
Altschul, Brett
- Subjects
- *
LORENTZ force , *LEPTONS (Nuclear physics) , *MESONS , *DECAY schemes (Radioactivity) , *LAGRANGIAN functions - Abstract
If the observation by OPERA of apparently superluminal neutrinos is correct, the Lagrangian for second-generation leptons must break Lorentz invariance. We calculate the effects of an energy-independent change in the neutrino speed on another observable, the charged pion decay rate. The rate decreases by a factor Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed, where
is the (directionally averaged) neutrino speed in the pion's rest frame. This provides a completely independent experimental observable that is sensitive to the same forms of Lorentz violation as a neutrino time-of-flight measurement. [ABSTRACT FROM AUTHOR] - Published
- 2011
- Full Text
- View/download PDF
33. Measuring the lifetime of trapped sleptons using the general purpose LHC detectors.
- Author
-
Pinfold, James L. and Sibley, Logan
- Subjects
- *
LEPTONS (Nuclear physics) , *SUPERGRAVITY , *SYMMETRY (Physics) , *METAPHYSICAL cosmology , *PARTICLES (Nuclear physics) , *DECAY schemes (Radioactivity) , *RADIOACTIVE decay - Abstract
In supergravity where the gravitino is the lightest supersymmetric particle, the next-to-lightest supersymmetric particle decays to the gravitino with a naturally long lifetime (104-108s). However, cosmological constraints favor charged slepton next-to-lightest supersymmetric particles with lifetimes below a year as the natural next-to-lightest supersymmetric particle candidate. For this scenario we report a method to accurately determine the slepton lifetime and supersymmetry cross section from observation of the decays of sleptons trapped in the material comprising the main detector (ATLAS, CMS). A measurement of the lifetime to 5% is possible after 3 yr at nominal luminosity and running conditions. This method is sensitive to the cosmologically preferred stau lifetime of ∼37 days and does not require the use of ancillary trapping volumes or special LHC experiment initiated beam dump requirements. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
34. Semileptonic B to scalar meson decays in the standard model with fourth generation.
- Author
-
Aslam, M. Jamil
- Subjects
- *
SCALAR field theory , *RADIOACTIVE decay , *DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) , *POLARIZATION (Nuclear physics) ,MESON decay - Abstract
We study the effects of the fourth generation of quarks on the total branching ratio and the lepton polarizations in B0→K0*(1430)l+l- (l=μ, τ) decay. Taking the fourth generation quark mass mt' of about 400 to 600 GeV with the mixing angle ∣Vt′b*Vt′s∣ in the range (0.05-1.4)×10-2 and using the phase to be 80°, it is found that the branching ratio and lepton polarizations are quite sensitive to these fourth generation parameters. In the future, the experimental study of this decay will give us an opportunity to study new physics effects, precisely, to search for the fourth generation of quarks (t′,b′) in an indirect way. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
35. Ratios of heavy hadron semileptonic decay.
- Author
-
Gronau, Michael and Rosner, Jonathan L.
- Subjects
- *
HADRONS , *LEPTONS (Nuclear physics) , *PARTICLE decays , *DECAY schemes (Radioactivity) , *KINEMATICS , *MESONS , *DUALITY (Nuclear physics) - Abstract
Ratios of charmed meson and baryon semileptonic decay rates appear to be satisfactorily described by considering only the lowest-lying (S-wave) hadronic final states and assuming the kinematic factor describing phase space suppression is the same as that for free quarks. For example, the rate for Ds semileptonic decay is known to be (17.0±5.3)% lower than those for D0 or D+, and the model accounts for this difference. When applied to hadrons containing b quarks, this method implies that the Bs semileptonic decay rate is about 1% higher than that of the nonstrange B mesons. This small difference thus suggests surprisingly good local quark-hadron duality for B semileptonic decays, complementing the expectation based on inclusive quark-hadron duality that these differences in rates should not exceed a few tenths of a percent. For Λb semileptonic decay, however, the inclusive rate is predicted to be about 13% greater than that of the nonstrange B mesons. This value, representing a considerable departure from a calculation using a heavy-quark expansion, is close to the corresponding experimental ratio Γ(Λb)/ Γ (B)=1.13±0.03 of total decay rates. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
36. Study of B → πℓν and B → ρℓν decays and determination of ∣Vub∣.
- Subjects
- *
RADIOACTIVE decay , *DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) , *PARTICLE decays , *DILEPTON production , *BRANCHING ratios , *MOMENTUM transfer , *PREDICTION models - Abstract
We present an analysis of exclusive charmless semileptonic B-meson decays based on 377×106 BB pairs recorded with the BABAR detector at the (4S) resonance. We select four event samples corresponding to the decay modes B0→ π-ℓ+ν, B+→ π0ℓ+ν, B0→ π-ℓ+ν, and B+→ π0ℓ+ν and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two B→ πℓν samples, and similarly the two B→ πℓν samples, and measure the branching fractions B(B0π-ℓ+ν)=(1.41±0.05±0.07)×10-4 and B(B0π-ℓ+ν)=(1.75±0.15±0.27)×10-4, where the errors are statistical and systematic. We compare the measured distribution in q2, the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the Cabibbo-Kobayashi-Maskawa matrix element ∣Vub∣. Based on the measured partial branching fraction for Bπℓν in the range q2<12 GeV2 and the most recent QCD light-cone sum-rule calculations, we obtain ∣Vub∣=(3.78±0.13-0.40+0.55)×10-3, where the errors refer to the experimental and theoretical uncertainties. From a simultaneous fit to the data over the full q2 range and the FNAL/MILC lattice QCD results, we obtain ∣Vub∣=(2.95±0.31)×10-3 from Bπℓν, where the error is the combined experimental and theoretical uncertainty. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
37. Search for neutrinoless decays
- Author
-
Yusa, Y.
- Subjects
- *
NEUTRINOS , *LEPTONS (Nuclear physics) , *NUCLEAR physics , *RADIOACTIVE decay , *DECAY schemes (Radioactivity) - Abstract
We have searched for neutrinoless τ lepton decays into one electron or niuon and two charged pion or kaon using a 158 fb−1 data sample collected with the Belle detector at the KEKB collider. Since the number of signal candidate events is compatible with the expected background, we set 90% confidence level upper limits on the branching fractions in the range (2.2 −15.5) × 10−7 for various decay modes where ℓ and h represent e or μ and or , respectively. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
38. Search for New Physics in Lepton Flavor Violating Decays at Belle
- Author
-
Enari, Y.
- Subjects
- *
LEPTONS (Nuclear physics) , *NUCLEAR physics , *RADIOACTIVE decay , *BRANCHING ratios , *DECAY schemes (Radioactivity) - Abstract
We here report on a search for lepton-flavor violating τ decays, , with a 153.8 fb−1 data recorded by the Belle detector at the KEKB asymmetric-energy collider. For each of the six decay modes, the observed yield is compatible with background and the 90% confidence level upper limits on the branching fraction are obtained as 0.13 −1.0 × 10-6 which are a factor of 9 to 74 times better than previous measurements. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
39. Search for the Lepton Flavor Violating decay in the MEG Experiment
- Author
-
Yamada, S.
- Subjects
- *
RADIOACTIVE decay , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *NUCLEAR physics - Abstract
Search for the Lepton Flavor Violation has a long history since the discovery of muon. The MEG experiment, a new experiment to search for the Lepton Flavor Violating decay , is approved and being build at the Paul Scherrer Institut, Switzerland. The status of preparations of the experiment, in particular, the liquid Xe scintillation gamma ray detector, is briefly described. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
40. Search for Lepton and Baryon Number Violating Decays into , , , and
- Author
-
Sato, N. and Miyazaki, Y.
- Subjects
- *
RADIOACTIVE decay , *DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) , *NUCLEAR physics - Abstract
We have searched for decays that violate both lepton and baryon number using data collected by the Belle detector at the KEKB asymmetric collider. No signals are found in , , , and and we set upper limits on the branching fractions of , , , and at the 90% confidence level. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
41. Search for Lepton Flavour Violation (LFV) in Three-Body Tau Decays at BaBar
- Author
-
Hodgkinson, M.
- Subjects
- *
LEPTONS (Nuclear physics) , *NUCLEAR physics , *RADIOACTIVE decay , *DECAY schemes (Radioactivity) - Abstract
The results of searches for Lepton Flavour Violating (LFV) decays at the BaBar detector located on the PEP-II collider, using data collected at an energy of 10.58 GeV, are presented. Upper limits at 90% Confidence Level (CL) are established in the range for six modes using 91.5 fb −1 of data and in the range for fourteen modes using 221.4 fb −1 of data. The results are preliminary. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
42. Measurement of the Strangeness Spectral Function and the Mass of the Strange Quark with the Opal Detector at LEP
- Author
-
Mader, Wolfgang
- Subjects
- *
LEPTONS (Nuclear physics) , *PARTICLES (Nuclear physics) , *RADIOACTIVE decay , *DECAY schemes (Radioactivity) , *NUCLEAR physics - Abstract
Tau lepton decays with open strangeness in the final state are measured with the Opal detector at LEP to determine the strange hadronic spectral function of the τ lepton and the mass of the strange quark. The decays , and with final states consisting of neutral and charged kaons and pions, have been studied. The invariant mass distribution of 93.4% of these final states have been experimentally determined. Monte Carlo simulations have been used for the remaining 6.6% and for the strange final states including η mesons. The reconstructed strange final states, corrected for resolution effects and detection efficiencies, yield the strange spectral function of the τ lepton. The moments of the spectral function which are important input parameters for theoretical analyses, are determined. From the CKM weighted difference of strange and non-strange spectral moments, the mass of the strange quark has been measured to be . Furthermore, the branching fractions and have been measured. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
43. Recent CLEO Results on Tau Hadronic Decays
- Author
-
Duboscq, J.E.
- Subjects
- *
RADIOACTIVE decay , *DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) , *NEUTRINOS , *NUCLEAR physics - Abstract
I outline recent results using CLEO3 data involving the decay of the τ to three charged hadrons and a neutrino, as well as an investigation of the structure of the decay and the Wess-Zumino term in this decay. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
44. Heavy to light vector meson semileptonic decays
- Subjects
- *
MESONS , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *NUCLEAR physics - Abstract
New (preliminary) results for the form factors relevant for the semileptonic decays of heavy pseudoscalar to a light vector meson are presented. In particular, we discuss the form factors for
D → K* andB → π modes. [Copyright &y& Elsevier]- Published
- 2003
- Full Text
- View/download PDF
45. Theoretical issues in the determination of <F>|Vub|</F>
- Author
-
Luke, Michael
- Subjects
- *
DECAY schemes (Radioactivity) , *LEPTONS (Nuclear physics) - Abstract
Theoretical issues in the determination of
|Vub| from inclusive decays are discussed, with emphasis on optimized cuts in the (q2, mx ) plane and the endpoint of the charged lepton spectrum. [Copyright &y& Elsevier]- Published
- 2003
- Full Text
- View/download PDF
46. MEASUREMENT OF R = B(t→Wb)/B(t→Wq) AT DØ.
- Author
-
STRANDBERG, JONAS
- Subjects
- *
BRANCHING ratios , *DECAY schemes (Radioactivity) , *QUARKS , *PARTICLES (Nuclear physics) , *LEPTONS (Nuclear physics) , *NUCLEAR physics , *JETS (Nuclear physics) , *NUCLEAR reactions - Abstract
A measurement of the ratio of branching fractions, R = B(t→Wb)/B(t→Wq), with q being any quark with I3 = -1/2 and Q = -1/3, is presented. This analysis considers samples of single- and double-tagged lepton+jets events obtained with the DØ detector, corresponding to integrated luminosities of 169 pb-1 and 158 pb-1, respectively in the e+jets and μ+jets channels. Two different lifetime taggers, CSIP and SVT, are used. [ABSTRACT FROM AUTHOR]
- Published
- 2005
47. LIMITS ON CHARGED HIGGS USING ${\rm t{\bar t}}$ CROSS SECTION MEASUREMENTS.
- Author
-
EUSEBI, RICARDO
- Subjects
- *
DECAY schemes (Radioactivity) , *BRANCHING ratios , *HIGGS bosons , *DILEPTON production , *LEPTONS (Nuclear physics) , *NUCLEAR physics - Abstract
We present the results of a search for charged Higgs in the decay products of ${\rm t{\bar t}}$ at the CDF II detector at the Tevatron. The search is based on the cross section measurements of ${\rm t{\bar t}}$ production in three exclusive decay channels: dilepton, lepton + jets and lepton + hadronic tau. Assuming the charged Higgs decays only via $H^+ \to {\rm c}{\rm \bar {s}}$, and $H^+ \to \tau {\bar \nu}$, and $H^+ \to {\rm t}^\ast {\rm b} \to {\rm Wb}{\rm \bar {b}}$, limits in the MSSM (mHiggs, tan(β)) plane are obtained at tree level. A model-independent analysis is introduced in which the results are independent of Higgs branching ratios. This analysis results in BR(t→Hb)<0.7 at 95%CL for 80 GeV
- Published
- 2005
48. New Insights Concerning Dimension Eight Effects in Weak Decays.
- Author
-
Donoghue, John F.
- Subjects
- *
LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
Most past work on weak nonleptonic decays has mixed dimensional regularization in the weak operator product expansion with some form of a cutoff regularization in the evaluation of the matrix elements. Even with the usual technique of matching the two schemes, this combination misses physics at short distance which can be described by dimension eight (and higher dimension) operators. I describe some recent work with V. Cirigliano and E. Golowich which clarifies these effects and provides a numerical estimate suggesting that they are important. [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
49. From factor ratio measurement in the decay Λ[sub c]→Λ e[sup +] ν.
- Author
-
Pavlunin, Victor and Shipsey, Ian
- Subjects
- *
LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
The hadronic current of the matrix element for the transition γ[sub c] → γ e[sup +] ν within the framework of HQET is parameterized in terms of two form factors. By studying the decay rate distribution in the space of the decay kinematic variables one can extract the ratio R = f[sub 2]/f[sub 1] of the form factors. The first measurement of R was made by the CLEO collaboration in 1995. In this note we describe the study of the statistical and systematic errors for a 4.5 times larger data sample. The central value for R will be presented shortly. [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
50. Search for τ[sup -]→μ[sup -]γ.
- Author
-
Kass, Richard
- Subjects
- *
LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
The decay τ[sup -] → μ[sup -]γ has been searched for using the CLEO detector at the Cornell Electron Storage Ring (CESR). Using 13.8fb[sup -1] of data collected with the CLEO II and CLEO II.V detector an upper limit of B(τ[sup -] → μ[sup -]γ)≤ 1.1 × 10[sup -6] @ 90% CL is obtained. [ABSTRACT FROM AUTHOR]
- Published
- 2001
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.