Lepton

The charged quantum geometry of mass-ENERGY-Matter - developed from the foundational postulate that quantised angular momenta of Planck's constant is in fact reflective of an equilateral mass-energy geometry from which all 2d immaterial EM fields and 3D material particles are created.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

We consider tri-bimaximal lepton mixing within low-scale seesaw schemes where light neutrino masses arise from TeV scale physics, potentially accessible at the Large Hadron Collider (LHC). Two examples are considered, based on the A4 flavor symmetry realized within the inverse or the linear seesaw mechanisms. Both are highly predictive so that in both the light neutrino sector effectively depends only on three mass parameters and one Majorana phase, with no CP violation in neutrino oscillations. We find that the linear seesaw leads to a lower bound for neutrinoless double beta decay while the inverse seesaw does not. The models also lead to potentially sizeable decay rates for lepton flavor violating processes, tightly related by the assumed flavor symmetry.

Recently, many authors showed that if the solar and atmospheric neutrino data are both described by maximal mixing vacuum oscillations at the relevant mass scale, then there exists a unique bi-maximal lepton mixing matrix for three neutrino flavors. We construct the lepton mass matrices from the symmetry principle so that maximal mixings for the atmospheric and the solar neutrino vacuum oscillations are naturally generated. Although the hierarchical patterns of the lepton sector are quite different from each other, we show how two different mass matrices suggested in this work can be generated in a unified way. We also give comments on possible future tests of the bi-maximal lepton mixing matrix.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

We propose a new mechanism for leptogenesis, which is naturally realized in models with a flavor symmetry based on the discrete group A 4 , where the symmetry breaking parameter also controls the Majorana masses for the heavy right handed (RH) neutrinos. During the early universe, for T TeV, part of the symmetry is restored, due to finite temperature contributions, and the RH neutrinos remain massless and can be produced in thermal equilibrium even at temperatures well below the most conservative gravitino bounds. Below this temperature the phase transition occurs and they become massive, decaying out of equilibrium and producing the necessary lepton asymmetry. Unless the symmetry is broken explicitly by Planck-suppressed terms, the domain walls generated by the symmetry breaking survive till the quark-hadron phase transition, where they disappear due to a small energy splitting between the A 4 vacua caused by the QCD anomaly. 1

A measurement of the top quark pair production (tt) cross section in proton-proton collisions at the centre-of-mass energy of 8 TeV is presented using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.6 fb −1. This analysis is performed in the tt decay channels with one isolated, high transverse momentum electron or muon and at least four jets, at least one of which is required to be identified as originating from hadronization of a b quark. The calibration of the jet energy scale and the efficiency of b jet identification are determined from data. The measured tt cross section is 228.5 ± 3.8 (stat) ± 13.7 (syst) ± 6.0 (lumi) pb. This measurement is compared with an analysis of 7 TeV data, corresponding to an integrated luminosity of 5.0 fb −1 , to determine the ratio of 8 TeV to 7 TeV cross sections, which is found to be 1.43 ± 0.04 (stat) ± 0.07 (syst) ± 0.05 (lumi). The measurements are in agreement with QCD predictions up to next-to-next-to-leading order.

In the light of renewed evidence for the existence of a 17 keV neutrino, we study the possible mass patterns for the charged and the neutral leptons, in the context of a generalized "seesaw"-type of model, which implements a horizontal U(l)A Peccei-Quinn symmetry. Under some general assumptions concerning the structure of the mass matrix we find that the mass hierarchy between the first two generations of charged leptons and the third one is explained in terms of the natural scales of the model. At the same time, with the additional assumption of the proportionality of Majorana-and Dirac-type couplings, the spectrum of the neutral leptons contains two very light Majorana neutrinos, such as required by the MSW interpretation of the solar neutrino deficit, and the 17 keV "Simpson" neutrino. A cosmologically consistent decay mode of this neutrino is into a~e and the axion. * We adopt the standard notation, where (i, J)k label respectively SU(2)L, SU(2)R representations, and k is the quantum number of U(1)fiL.

We present a general self-consistent lepto/hadronic jet model for the non-thermal electromagnetic emission of microquasars. The model is applied to the low-mass microquasar (LMMQ) GX 339-4 and predicts its high-energy features. We assume that both leptons and hadrons are accelerated up to relativistic energies by diffusive shock acceleration, and calculate their contribution to the electromagnetic spectrum through all main radiative processes. The radiative contribution of secondary particles (pions, muons and electron-positron pairs) is included. We use a set of simultaneous observations in radio and X-rays to constrain the model parameters and find the best fit to the data. We obtain different spectral energy distributions that can explain the observations, and make predictions for the high-energy emission. Observations with gamma-ray instruments like Fermi can be used to test the model and determine the proton content of the jets. Finally, we estimate the positron injection in the surrounding medium. Our findings support the suggested association between LMMQs and the observed distribution of the 511 keV line flux observed by INTEGRAL.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

Electron, proton and neutron are described in terms of energy densities on least-action paths to show that their charges, magnetic mo ments and masses are man ifestations of quantized geodesics. According to this geometric understanding of matter, the mass of a part icle depends on how much the particle-associated curved path projects onto the straight paths of the universal surrounding energy density. The reference density of free space is embodied by the most elementary actions, the photons in propagation on their least-time paths. The vacuum density with rando m distribution of photon phases displays no electromagnetic field, yet the propagation of its force carriers will level off density differences. This manifests itself as gravitation. Transformations fro m one particle to another, for examp le oscillations, are described according to Noether's theorem as changes from one action to another. This physical portrayal of quantized nature, where every entity comprises mu ltip les of the most elementary action, parallels the atomistic tenet.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

Context. The so-called excess of cosmic ray (CR) positrons observed by the PAMELA satellite up to 100 GeV has led to many interpretation attempts, from standard astrophysics to a possible exotic contribution from dark matter annihilation or decay. The Fermi data subsequently obtained about CR electrons and positrons in the range 0.02-1 TeV, and HESS data above 1 TeV have provided additional information about the leptonic content of local Galactic CRs. Aims. We analyse predictions of the CR lepton fluxes at the Earth of both secondary and primary origins, evaluate the theoretical uncertainties, and determine their level of consistency with respect to the available data. Methods. For propagation, we use a relativistic treatment of the energy losses for which we provide useful parameterizations. We compute the secondary components by improving on the method that we derived earlier for positrons. For primaries, we estimate the contributions from astrophysical sources (supernova remnants and pulsars) by considering all known local objects within 2 kpc and a smooth distribution beyond. Results. We find that the electron flux in the energy range 5-30 GeV is well reproduced by a smooth distant distribution of sources with index γ ∼ 2.3 − 2.4, while local sources dominate the flux at higher energy. For positrons, local pulsars have an important effect above 5-10 GeV. Uncertainties affecting the source modeling and propagation are degenerate and each translates into about one order of magnitude error in terms of local flux. The spectral shape at high energy is weakly correlated with the spectral indices of local sources, but more strongly with the hierarchy in their distance, age and power. Despite the large theoretical errors that we describe, our global and self-consistent analysis can explain all available data without over-tuning the parameters, and therefore without the need to consider any exotic physics. Conclusions. Though a standard paradigm of Galactic CRs is well established, our results show that we can hardly talk about any standard model of CR leptons, because of the very large theoretical uncertainties. Our analysis provides details about the impact of these uncertainties, thereby sketching a roadmap for future improvements.

In the light of renewed evidence for the existence of a 17 keV neutrino, the possible mass patterns for the charged and the neutral leptons are studied. The investigation is performed in the context of a generalized seesaw type of model, which implements a horizontal U(1)(sub A) Peccei-Quinn symmetry. Under some general assumptions concerning the structure of the mass matrix, it is found that the mass hierarchy between the first two generations of charged leptons and the third one is explained in terms of the natural scales of the model. An additional assumption is made; namely, that the Majorana and Dirac type coupling constants, generally assumed to be independent to each other, are proportional. In this model, the spectrum contains an intermediate mass Dirac tau neutrino and two very light Majorana states, which are essentially the electron and the muon neutrinos. Identifying the 17 keV neutrino with the Dirac state, and using the bounds on the Peccei-Quinn scale, it is found that the mass of the two light states turns out to be in the right range, required by the Mikheyev-Smirnov-Wolfenstein solution of the solar neutrino problem. A cosmologically consistent lifetime for the Simpson neutrino is obtained through its decay into an axion and the electron neutrino.

A search is presented for standard model (SM) production of four top quarks (tttt) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6 fb −1 recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM tttt production is σ SM tttt ≈ 1 fb. A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. The data are consistent with expectations of the SM, and an upper limit of 32 fb is set at a 95% confidence level on the cross section for producing four top quarks in the SM, where a limit of 32 ± 17 fb is expected.

This article reports world averages of measurements of b-hadron, c-hadron, and τ -lepton properties obtained by the Heavy Flavor Averaging Group using results available through summer 2016. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays, and Cabbibo-Kobayashi-Maskawa matrix elements.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± μ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95 % C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eμX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

The procedures for studying a single narrow s-channel resonance or nearly degenerate resonances at a lepton collider, especially a muon collider, are discussed. In particular, we examine four methods for determining the parameters of a narrow s-channel resonance: scanning the resonance, measuring the convoluted cross section, measuring the Breit-Wigner area, and sitting on the resonance while varying the beam energy resolution. This latter procedure is new and appears to be potentially very powerful. Our focus is on computing the errors in resonance parameters resulting from uncertainty in the beam energy spread. Means for minimizing these errors are discussed. The discussion is applied to the examples of a light SM-Higgs, of the lightest pseudogoldstone boson of strong electroweak breaking, and of the two spin-1 resonances of the Degenerate BESS model (assuming that the beam energy spread is less than their mass splitting). We also examine the most effective procedures for nearly degenerate resonances, and apply these to the case of Degenerate BESS resonances with mass splitting of order the beam energy spread.

We present a search for the standard model Higgs boson produced in association with a W boson in ffiffi ffi s p ¼ 1:96 TeV p p collision data collected with the CDF II detector at the Tevatron corresponding to an integrated luminosity of 9:45 fb À1 . In events consistent with the decay of the Higgs boson to a bottomquark pair and the W boson to an electron or muon and a neutrino, we set 95% credibility level upper limits on the WH production cross section times the H ! b b branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV=c 2 , we observe (expect) a limit of 4.9 (2.8) times the standard model value.

... g (r'41 )+g(r'jk2) 2P;J 1 1 rj Rp which of course is only a very rough guess of the effect of this radial dependence on the nuclear ma-trix elements. We instead make the approximation g ('r411,2 =)g(r"ko) with Tp Co=&Ear&+ 2 +m. EI=k,2—— Page 4. ...

Within the Standard Model Effective Field Theory framework, with operators up to dimension 6, we perform a model-independent analysis of the lepton-flavour-violating processes involving tau leptons. Namely, we study hadronic tau decays and ℓ-τ conversion in nuclei, with ℓ = e, μ. Based on available experimental limits, we establish constraints on the Wilson coefficients of the operators contributing to these processes. Our work paves the way to extract the related information from Belle II and foreseen future experiments.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

Theoretical calculation of transverse momentum(p T) distribution of thermal photons and dileptons originating from ultra-relativistic heavy ion collisions suffer from several uncertainties since the evaluation of these spectra needs various inputs which are not yet known unambiguously. In the present work the ratio of the p T spectra of thermal photons to lepton pairs has been evaluated and it is shown that the ratio is insensitive to some of these parameters.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.

In the light of renewed evidence for the existence of a 17 keV neutrino, we study the possible mass patterns for the charged and the neutral leptons, in the context of a generalized "seesaw"-type of model, which implements a horizontal U(l)A Peccei-Quinn symmetry. Under some general assumptions concerning the structure of the mass matrix we find that the mass hierarchy between the first two generations of charged leptons and the third one is explained in terms of the natural scales of the model. At the same time, with the additional assumption of the proportionality of Majorana-and Dirac-type couplings, the spectrum of the neutral leptons contains two very light Majorana neutrinos, such as required by the MSW interpretation of the solar neutrino deficit, and the 17 keV "Simpson" neutrino. A cosmologically consistent decay mode of this neutrino is into a~e and the axion.

When quarks and leptons propagate in the background of a grand unified cosmic string, various baryon number violating processes can occur. We argue that, because of the long-range pure gauge field that surrounds the string, the cross sections for these processes are generically enhanced by large factors over the naive, geometric, cross section. We explicitly calculate the cross section for quark to lepton transitions in a simplified model and find that it is enhanced by a factor of up to (z~_/Mproton) 2 where A is the grand unification scale. In an appendix we discuss the possible boundary conditions for the fermionic wave functions, and calculate the correct choice of boundary condition for our model system.

We describe current and future hadron collider limits on new vector-like leptons with exotic decays. We consider the possibility that, besides standard decays, the new leptons can also decay into a Standard Model charged lepton and a stable particle like a dark photon. To increase their applicability, our results are given in terms of arbitrary branching ratios in the different decay channels. In the case that the dark photon is stable at cosmological scales we discuss the interplay between the dark photon and the vector-like lepton in generating the observed dark matter relic abundance and the complementarity of collider searches and dark matter phenomenology.

A search for new physics in proton-proton collisions having final states with an electron or muon and missing transverse energy is presented. The analysis uses data collected in 2012 with the CMS detector, at an LHC center-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of 19.7 fb −1. No significant deviation of the transverse mass distribution of the charged lepton-neutrino system from the standard model prediction is found. Mass exclusion limits of up to 3.28 TeV at 95% confidence level for a W boson with the same couplings as that of the standard model W boson are determined. Results are also derived in the framework of split universal extra dimensions, and exclusion limits on Kaluza-Klein W (2) KK states are found. The final state with large missing transverse energy also enables a search for dark matter production with a recoiling W boson, with limits set on the mass and the production cross section of potential candidates. Finally, limits are established for a model including interference between a left-handed W boson and the standard model W boson, and for a compositeness model.

Understanding the role of muons in Particle Physics is an important step understanding generations and the origin of mass as an expression of "internal structure". A possible connection between muonic atoms and cycloatoms is used as a pretext to speculate on the above core issue of the Standard Model.

A search for new physics in proton-proton collisions having final states with an electron or muon and missing transverse energy is presented. The analysis uses data collected in 2012 with the CMS detector, at an LHC center-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of 19.7 fb −1. No significant deviation of the transverse mass distribution of the charged lepton-neutrino system from the standard model prediction is found. Mass exclusion limits of up to 3.28 TeV at 95% confidence level for a W boson with the same couplings as that of the standard model W boson are determined. Results are also derived in the framework of split universal extra dimensions, and exclusion limits on Kaluza-Klein W (2) KK states are found. The final state with large missing transverse energy also enables a search for dark matter production with a recoiling W boson, with limits set on the mass and the production cross section of potential candidates. Finally, limits are established for a model including interference between a left-handed W boson and the standard model W boson, and for a compositeness model.

A search for supersymmetry (SUSY) is presented where at least one Higgs boson is produced and decays to two photons in the decay chains of pair-produced SUSY particles. Two analysis strategies are pursued: one focused on strong SUSY production and the other focused on electroweak SUSY production. The presence of charged leptons, additional Higgs boson candidates, and various kinematic variables are used to categorize events into search regions that are sensitive to different SUSY scenarios. The results are based on data from proton-proton collisions at the Large Hadron Collider at a center-of-mass energy of 13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 77.5 fb−1. No statistically significant excess of events is observed relative to the standard model expectations. We exclude bottom squark pair production for bottom squark masses below 530 GeV and a lightest neutralino mass of 1 GeV; wino-like chargino-neutralino production in gauge-mediated SUS...

We measure the mass of the top quark in lepton+jets final states using the full sample of pp collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at sqrt[s] = 1.96 TeV, corresponding to 9.7 fb(-1) of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from tt production or background. The overall jet energy scale is constrained in situ by the mass of the W boson. We measure m(t) = 174.98 ± 0.76 GeV. This constitutes the most precise single measurement of the top-quark mass.

A search for a standard model Higgs boson decaying into a pair of τ leptons is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012. The dataset corresponds to an integrated luminosity of 4.9 fb −1 at a centre-of-mass energy of 7 TeV and 19.7 fb −1 at 8 TeV. Each τ lepton decays hadronically or leptonically to an electron or a muon, leading to six different final states for the τ-lepton pair, all considered in this analysis. An excess of events is observed over the expected background contributions, with a local significance larger than 3 standard deviations for m H values between 115 and 130 GeV. The best fit of the observed H → ττ signal cross section times branching fraction for m H = 125 GeV is 0.78 ± 0.27 times the standard model expectation. These observations constitute evidence for the 125 GeV Higgs boson decaying to a pair of τ leptons.

We present a search for the standard model Higgs boson produced in association with a W boson in √ s = 1.96 TeV p-pbar collision data collected with the CDF II detector at the Tevatron corresponding to an integrated luminosity of 9.45 fb -1 . In events consistent with the decay of the Higgs boson to a bottom-quark pair and the W boson to an electron or muon and a neutrino, we set 95% credibility level upper limits on the W H production cross section times the H → b b branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV/c 2 we observe (expect) a limit of 4.9 (2.8) times the standard model value.

Motivated by the recent measurements of the Bs − Bs mass difference from the DØ and CDF collaborations, we probe new physics effects in the Bq − Bq mixing within the context of the supersymmetric grand unified model (SUSY GUT). We find that new physics effects in B s(d) − B s(d) mixing lead to the correlated information in the branching fractions of the lepton flavor violating decays, which may serve as a test of the SUSY GUT. We also discuss the implication of such new physics effects on the quark-lepton complementarity in the neutrino mixings.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e ± µ ∓ continuum using 2.1 fb −1 of data collected by the ATLAS detector in √ s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp → eµX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for mt = 95 GeV to 30 fb for mt = 1000 GeV.