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Lepton-flavor mixing and K --> pi nu nu bar decays

Description: The impact of possible sources of lepton-flavor mixing on K {yields} {pi}{nu}{bar {nu}} decays is analyzed. At the one-loop level lepton-flavor mixing originated from non-diagonal lepton mass matrices cannot generate a CP-conserving K{sub L} {yields} {pi}{sup 0}{nu}{bar {nu}} amplitude. The rates of these modes are sensitive to leptonic flavor violation when there are at least two different leptonic mixing matrices. New interactions that violate both quark and lepton universalities could enhance the CP-conserving component of {Lambda}(K{sub L} {yields} {pi}{sup 0}{nu}{bar {nu}}) and have a substantial impact. Explicit examples of these effects in the context of supersymmetric models, with and without R-parity conservation, are discussed.
Date: November 26, 2003
Creator: Grossman, Yuval; Isidori, Gino & Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

Study of a like-sign dilepton search for chargino-neutralino production at CDF

Description: We propose a like-sign dilepton search for chargino-neutralino production in p#22; p collisions at ps = 1:8 TeV, which complements the previously published trilepton search by the CDF detector using Fermilab Run I data. Monte Carlo predictions for the signal and background e#14;ciencies indicate a signi#12;cant increase in sensitivity to chargino-neutralino production compared to the traditional trilepton analysis alone.
Date: March 2, 1999
Creator: Worcester, Matthew
Partner: UNT Libraries Government Documents Department

Search for neutral heavy leptons in the NuTeV experiment at Fermilab

Description: Preliminary results are presented from a search for neutral heavy leptons in the NuTeV experiment at Fermilab. The upgraded NuTeV neutrino detector for the 1996-1997 run included an instrumented decay region for the NHL search which, combined with the NuTeV calorimeter, allows detection in several decay modes ({mu}{mu}{nu}, {mu}e{nu}, {mu}{pi}, e{pi}, and ee{nu}). We see no evidence for neutral heavy leptons in our current search in the mass range from 0.3 GeV to 2.0 GeV decaying into final states containing a muon.
Date: December 1, 1998
Creator: Drucker, R.B.
Partner: UNT Libraries Government Documents Department

The future of fixed target physics: Snowmass E5 working group summary

Description: Fixed target experimentation remains a vigorous and important tool. In many cases it provides the best technique to study elementary physics. Here the authors explore several areas, where, in the near future, fixed target experiments have the potential to alter the understanding of physics. These include, but are clearly not limited to, high precision tests of CP violation in the Kaon sector, ultra-precise determination of the weak mixing angle and its evolution, and lepton flavor violation.
Date: December 10, 2002
Creator: al., Krishna Kumar et
Partner: UNT Libraries Government Documents Department

The signature of sequential charged leptons

Description: I am honored to be invited to give a talk on this occasion to celebrate Martin Perl`s 65th birthday. John Jaros, the organizer of this occasion, wanted me to recollect several things, especially: what motivated me to write my 1971 Physical Review paper on the heavy lepton entitled ``Decay Correlations of Heavy Lepton in e{sup minus} + e{sup +} = {ell}{sup -} + {ell}+;`` why did I think of muon-electron coincidence; and what were the contributions of Thacker and Sakurai. In this paper I answer his requests and add something else later.
Date: December 1, 1992
Creator: Tsai, Y. S.
Partner: UNT Libraries Government Documents Department

Drell-Yan Lepton Pair Azimuthal Asymmetry in Hadronic Processes

Description: We study the azimuthal asymmetry in the Drell-Yan lepton pair production in hadronic scattering processes at moderate transverse momentum region, taking into account the contributions from the twist-three quark-gluon correlations from the unpolarized hadrons. The contributions are found to dominate the asymmetry, and are not power suppressed by qt/Q at small qt where qt and Q are the transverse momentum and invariant mass of the lepton pair. Accordingly, the Lam-Tung relation will be violated at this momentum region, and its violation depends on the twist-three functions. However, at large transverse momentum qt~;;Q, the Lam-Tung relation still holds because all corrections are power suppressed by Lambda2/qt2 ~;; Lambda2/Q2 where Lambda is the typical nonperturbative scale.
Date: January 22, 2009
Creator: Zhou, Jian; Yuan, Feng & Liang, Zuo-Tang
Partner: UNT Libraries Government Documents Department

Limits on tau lepton flavor violating decays in three charged leptons

Description: A search for the neutrinoless, lepton-flavor violating decay of the {tau} lepton into three charged leptons has been performed using an integrated luminosity of 468 fb{sup -1} collected with the BABAR detector at the PEP-II collider. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range (1.8-3.3) x 10{sup -8} at 90% confidence level.
Date: April 29, 2010
Creator: Cervelli, Alberto
Partner: UNT Libraries Government Documents Department

Search for quark-lepton compositeness in the dimuon final state at D0

Description: We used the upgraded D0 detector at the Tevatron at {radical}s = 1.96 TeV to collect data in a search for a compositeness signature of quarks and leptons. This analysis uses an integrated luminosity of 400 pb{sup -1}. The high-mass dimuon mass spectrum is compared with that predicted by Drell-Yan (DY) scattering, modified by a contact interaction. This interaction is parameterized by a compositeness energy scale factor {Lambda}. Preliminary limits on {lambda} are set at the 95% confidence level for constructive and destructive interference between the DY amplitude and the contact interaction for various quark and lepton chiralities.
Date: January 1, 2005
Creator: Xuan, Nguyen Phuoc & U., /Notre Dame
Partner: UNT Libraries Government Documents Department

Anomalous Flavor U(1)_X for Everything

Description: We present an ambitious model of flavor, based on an anomalous U(1)_X gauge symmetry with one flavon, only two right-handed neutrinos and only two mass scales: M_{grav} and m_{3/2}. In particular, there are no new scales introduced for right-handed neutrino masses. The X-charges of the matter fields are such that R-parity is conserved exactly, higher-dimensional operators are sufficiently suppressed to guarantee a proton lifetime in agreement with experiment, and the phenomenology is viable for quarks, charged leptons, as well as neutrinos. In our model one of the three light neutrinos automatically is massless. The price we have to pay for this very successful model are highly fractional X-charges which can likely be improved with less restrictive phenomenological ansatze for mass matrices.
Date: December 1, 2003
Creator: Dreiner, Herbi K.; Murayama, Hitoshi & Thormeier, Marc
Partner: UNT Libraries Government Documents Department

A Proposal to Continue Measurements of Direct Muon Production in the Forward Direction

Description: The authors recently have measured the direct muon production in the forward direction at small p{perpendicular} and find a large direct muon to pion ratio. At x = 0.3 the ratio is {mu}{sup -}/{pi}{sup -} = 1.83 {+-} 0.43 x 10{sup -4} for negatives and {mu}{sup +}/{pi}{sup +} = 6.4 {+-} 1.3 x 10{sup -5} for positives. The direct production of {mu}{sup +} and {mu}{sup -} are equal although the {pi}{sup +}/{pi}{sup -} ratios is large. They propose to continue these measurements and extend them to higher x. These new measurements would also include the A dependence of the {mu}/{pi} ratio. Based on their experience with this apparatus, they believe it is possible to extend these measurements of single lepton production to production by incident pions and kaons.
Date: October 20, 1975
Creator: Buchholz, D.; U., /Northwestern; Frisch, H.J.; Shochet, M.J.; /Chicago U., EFI; Johnson, Rolland P. et al.
Partner: UNT Libraries Government Documents Department


Description: Results on physics at RHIC using outgoing leptons and photons will be presented from Au+Au collisions at nucleon-nucleon c.m. energies {radical}(sNN) = 130 GeV and 200 GeV, and from p-p collisions at {radical}(sNN) = 200 GeV. Introduction and motivation will be presented both from the theoretical and experimental perspectives. Topics include open charm production via single e{sup {+-}}, J/{Psi} {yields} e{sup +} + e{sup -}, {mu}{sup +} + {mu}{sup -} and inclusive photon production.
Date: January 6, 2003
Partner: UNT Libraries Government Documents Department

Photoproduction Experiment at Fermilab

Description: The authors propose to continue and extend the program of photoproduction and pair production studies currently being carried out in Experiment E-87. The goals of the physics program they propose are: (1) to look for {mu}{sup {+-}}+e{sup {-+}}{nu}'s final states; (2) to study the mass spectra of hadronic final states which are produced in association with a single charged lepton (electron or muon); and (3) to determine the properties of a selected number of photoproduced multi-body hadronic final states; in particular: {gamma} + A {yields} ({bar p}p{pi}{sup +}{pi}{sup -}) + A {yields} ({pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup 0}) + A {yields} (K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}) + A {yields} (K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup 0}) + A etec., etc. The need for a heavy lepton pair production experiment is more crucial today than when they first proposed this experiment five years ago. The {mu}e pairs observed recently at SPEAR can be interpreted as arising from the decay of 2 GeV/c{sup 2} heavy leptons. They feel there is a compelling need to demonstrate that such {mu}e pairs are observed in at least one other reaction before such an interpretation can be considered completely satisfactory. To the best of their knowledge, the only independent reaction in which one might expect to observe such events is the pair production of heavy leptons. The broad band photon beam at Fermilab is perhaps the only beam in which such a pair production experiment is feasible. In addition, the probability of mis-identifying two hadrons as a {mu}e pair is extremely small (10{sup -6}) at Fermilab energies - several orders of magnitude smaller than at SPEAR. The primary motivation for examining the photoproduced hadronic final states such as {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup 0} and K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup 0} is to search for structure in ...
Date: October 1, 1975
Creator: Knapp, B.; Lee, W.; Moscoso, L.; Sokolsky, P.; U., /Columbia; Gladding, G. et al.
Partner: UNT Libraries Government Documents Department

A search for the production of Direct Leptons in nucleon-nucleus and nucleus-nucleus collisions. Progress report, April 1, 1991--December 1, 1993

Description: The purpose of this report is to describe activities performed by the Intermediate Energy Nuclear Physics Group (IENPG) at the Louisiana State University (LSU) under the terms of grant FG05-88ER40445. The report will cover, for the most part, the period of time between April 1, 1991, and the present. The principal focus of our activities is currently the muon subgroup of the PHENIX Collaboration. We are, however, in the process of concluding other activities, specifically our memberships in the Di-Lepton Spectrometer (DLS) Collaboration at LBL and the AMY Collaboration at KEK. These activities have been thoroughly discussed in previous progress reports and renewal proposals, and further discussion of these activities is possibly repetitious. However, this report has been prepared under the assumption that none of the referees with the exception of the grant monitor is familiar with the group or its previous work. Consequently we shall cite a few examples of our contributions to these collaborations when there seem to be valid reasons for so doing.
Date: December 15, 1993
Creator: Kirk, P. N.
Partner: UNT Libraries Government Documents Department

The discovery of the tau lepton: Part 1, The early history through 1975; Part 2, Confirmation of the discovery and measurement of major properties, 1976--1982

Description: Several previous papers have given the history of the discovery of the {tau} lepton at the Stanford Linear Accelerator Center (SLAC). These papers emphasized (a) the experiments which led to our 1975 publication of the first evidence for the existence of the {tau}, (b) the subsequent experiments which confirmed the existence of the r, and (c) the experiments which elucidated the major properties of the {tau}. That history will be summarized in Part 2 of this talk. In this Part 1, I describe the earlier thoughts and work of myself and my colleagues at SLAC in the 1960`s and early 1970`s which led to the discovery. I also describe the theoretical and experimental events in particle physics in the 1960`s in which our work was immersed. I will also try to describe for the younger generations of particle physicists, the atmosphere in the 1960`s. That was before the elucidation of the quark model of hadrons, before the development of the concept of particle generations The experimental paths to program we hot as clear as they are today and we had to cast a wide experimental net.
Date: August 1, 1994
Creator: Perl, M. L.
Partner: UNT Libraries Government Documents Department

Tau physics

Description: This report discusses the following topics: {tau} production and related {tau} properties; general discussion of {tau} decays; leptonic decays; hadronic decays; the {tau} in atomic physics; and the {tau} neutrino: {nu}{sub {tau}}
Date: March 1, 1993
Creator: Perl, M. L.
Partner: UNT Libraries Government Documents Department

Energy distribution of the leptons in top decay to charged Higgs

Description: We analyze the energy, distribution of the leptons coming from the top decay t {yields} bH{sup +}, bW{sup +} {yields} bl{sup +}v. The correlation between the lepton energy distribution and the top spin may be useful for distinguishing the H{sup +} signature from the W background. Such a correlation can also be useful for disentangling the two different H{sup +}{bar t}b couplings and determining the experimental value of tan {beta}.
Date: September 1, 1993
Creator: Pomarol, A. & Schmidt, C. R.
Partner: UNT Libraries Government Documents Department

Vector leptoquark production at hadron colliders

Description: We explore the production of vector leptoquarks(V) at the Tevatron, LHC, and SSC through both quark-antiquark and gluon fusion: q{bar q}, gg {yields} VV. The cross sections are found to be somewhat larger than for scalar leptoquarks of the same mass implying enhanced search capabilities.
Date: September 1, 1993
Creator: Hewett, J. L.; Rizzo, T. G.; Pakvasa, S.; Haber, H. E. & Pomarol, A.
Partner: UNT Libraries Government Documents Department

Are there atmospheric neutrino oscillations

Description: The neutrino oscillation explanation ([nu][sub [mu]] [yields] [nu][sub [tau]]) of the atmospheric neutrino deficit is often discussed but is far from widely accepted. This paper discusses several experimental observations, and how a consistent picture pointing towards neutrino oscillations might develop.
Date: January 1, 1993
Creator: Goodman, M.C.
Partner: UNT Libraries Government Documents Department