neutral current: flavor changing

Top PDF neutral current: flavor changing:

Search for Flavor-Changing Neutral-Current Charm Decays

Search for Flavor-Changing Neutral-Current Charm Decays

Figure 1: Standard model short-distance contributions to the c → uℓ + ℓ − transition. 1 INTRODUCTION In the Standard Model (SM), flavor-changing neutral-current (FCNC) processes cannot occur at the tree level. FCNC processes therefore provide an excellent tool for investigating the quantum corrections in the SM as a way to search for evidence of physics beyond the SM. FCNC processes have been studied extensively for K and B mesons in K 0 −K 0 and B 0 −B 0 mixing processes and in

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A search for the flavor-changing neutral current decay $B^0_s \rightarrow \mu^+ \mu^-$ in $p\overline{p}$ collisions at $\sqrt{s}$ = 1.96 TeV with the DO detector

A search for the flavor-changing neutral current decay $B^0_s \rightarrow \mu^+ \mu^-$ in $p\overline{p}$ collisions at $\sqrt{s}$ = 1.96 TeV with the DO detector

The purely leptonic decays B 0 d,s → µ + µ − [1] are flavor- changing neutral current (FCNC) processes. In the stan- dard model (SM), these decays are forbidden at the tree level and proceed at a very low rate through higher- order diagrams. The SM leptonic branching fractions (B)

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Search for production of single top quarks via $tcg$ and $tug$ flavor-changing neutral current couplings

Search for production of single top quarks via $tcg$ and $tug$ flavor-changing neutral current couplings

g /Λ and κ u g /Λ. To estimate systematic uncertainties, we consider ef- fects that alter the overall normalization of the distri- butions and those that also change their shapes. The dominant normalization effects are from lepton identifi- cation (4%), integrated luminosity measurement (6.5%), and cross section estimates. The uncertainties on cross sections vary from 9% for diboson production to 16% for SM single top quark production and 18% for t¯ t sam- ples [26]. The latter two include the uncertainty due to the top quark mass. For the FCNC signal, we factor out the parameter (κ g /Λ) 2 from the cross section, and as- sume an uncertainty of 15% on the remaining quantity based on a discussion in Ref. [17] on how the theoreti- cal predictions depend on the particular choice of factor- ization scale. The W +jets and multijets samples have an overall uncertainty of 4% from their normalization to data [3]. This includes an uncertainty of 25% on the heavy flavor fraction of the W +jets sample.
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Search for the flavor-changing neutral current interactions of the top quark and the Higgs boson which decays into a pair of b quarks at $\sqrt{s}=$ 13 TeV

Search for the flavor-changing neutral current interactions of the top quark and the Higgs boson which decays into a pair of b quarks at $\sqrt{s}=$ 13 TeV

4 Event selection The particle-flow (PF) algorithm [ 35 ] reconstructs and identifies each individual particle with an optimized combination of information from the various elements of the CMS de- tector. The energy of photons is directly obtained from the ECAL measurement, corrected for zero-suppression effects. The energy of electrons is determined from a combination of the electron momentum at the primary interaction vertex as determined by the tracker, the energy of the corresponding ECAL cluster, and the energy sum of all bremsstrahlung photons spatially compatible with originating from the electron track. The momentum of muons is obtained from the curvature of the corresponding track. The energy of charged hadrons is determined from a combination of their momentum measured in the tracker and the matching ECAL and HCAL energy deposits, corrected for zero-suppression effects and for the response function of the calorimeters to hadronic showers. Finally, the energy of neutral hadrons is obtained from the corresponding corrected ECAL and HCAL energy.
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Analysis of B [sigma] flavor oscillations at CDF

Analysis of B [sigma] flavor oscillations at CDF

A likelihood fitting framework is implemented and appropriate models and tech- niques developed for describing the mass, proper decay time, and flavor tagging char- a[r]

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Competitively Neutral Universal Service Obligations

Competitively Neutral Universal Service Obligations

5.2. Competitive neutrality This section highlights the analogy between the above approach to USO financing and the concept of competitive neutrality. Competitive neutrality has often been proposed as a qualifying criterion for the universal service and its supporting mechanism, especially in telecommunications. In the US, the FCC requires that the universal service support mechanisms and rules should be competitively neutral. In this context, competitive neutrality means that universal service support mechanisms and rules neither unfairly advantage nor disadvantage one provider over another. Broadly speak- ing, the universal service and its financing are competi- tively neutral if they do not create a competitive advantage or disadvantage for either the provider or the competitors. One possible way to interpret this require- ment (adopted for instance by Choné et al., 2002 ) is to re- quire that the profit of the designated provider is at least as big as the profit it would collect if it were relieved from the USO (in the scenario C).
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A search for flavour changing neutral currents in top-quark decays in pp collision data collected with the ATLAS detector at sqrt(s) = 7 TeV

A search for flavour changing neutral currents in top-quark decays in pp collision data collected with the ATLAS detector at sqrt(s) = 7 TeV

HERA [ 31 , 32 ] colliders, and at the LHC [ 33 ]. The best current direct search limits on the top quark FCNC branching fraction are 3.2% for both t → qγ [ 23 ] and t → Zq (q = u, c) [ 24 ]. This article reports a search for FCNC top-quark decays in t¯ t events. Events were searched for in which either the top or antitop quark has decayed into a Z boson and a quark, t → Zq, while the remaining top or antitop quark decayed through the SM t → W b channel. Only leptonic decays of the Z and W bosons were considered, yielding a final- state topology characterised by the presence of three isolated charged leptons, at least two jets, and transverse momentum imbalance (E T miss ) from the undetected neutrino arising from the W -boson decay. Leptons are either well-identified electron or muon candidates, selected using the full detector or, to increase signal acceptance, isolated tracks. Channels with τ leptons are not explicitly reconstructed, but reconstructed electrons and muons can arise from leptonic τ decays, and an isolated track can arise from hadronic τ decay modes.
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Changing time and emotions

Changing time and emotions

which manipulate the emotional valence in waiting conditions (Curton and Lordahl 1974; Edmonds, Cahoon, and Bridges 1981; Langer, Wapner, and Werner 1961). The problem with waiting time conditions is that subjects are not engaging in any task and one can- not control if and what people are thinking while they are waiting. It is thus dif- ficult for a psycho-physiologist to measure cognitive and emotional activity appropri- ately (Angrilli et al. 1997). Those kinds of experiments found for instance shorter time estimates for subjects in fear of a coming danger than for subjects in neutral condi- tion Langer, Wapner, and Werner (1961). Inversely, Edmonds, Cahoon, and Bridges (1981) show that subjects who expect a pleasant experience overestimate the actual interval time (time passed relatively slowly for them). Fraisse (1984) argues that the expectation of an agreeable event “leads to paying more attention to the passing of time” (p.24).
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A Changing Wind Collision

A Changing Wind Collision

For XMM-Newton spectra, there is a clear hardening of the emission of HD 5980 in 2016 compared to that recorded in previous years (see also middle panel of Fig. 6). This hard- ening does not seem to be linked to changing temperatures (since they appear quite similar whatever the year considered) but rather to an increase in absorbing columns with time (Ta- ble 2, Fig. 5). However, the larger noise in older data com- plicates the comparison so our interpretation of the origin of the observed hardening should be viewed with some caution. In contrast, the fits of both Chandra spectra, which have min- imal contamination by the SNR, show only a slight increase in absorption and a slight decrease in temperature, formally not significant as they remain within 1σ. For them, there is thus mostly a flux variation (see also left panel of Fig. 6). It is however important to note that these exposures were taken at different phases (φ=0.27 and 0.82) and the spectra are unfor- tunately noisier than the XMM-Newton ones, rendering de- tailed comparisons difficult.
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The role of lepton flavor symmetries in leptogenesis

The role of lepton flavor symmetries in leptogenesis

The presence of flavor symmetries in the lepton sector may have several consequences for the generation of the baryon asymmetry of the Universe via leptogenesis. We review the mechanism in general type-I, type-II and type- III seesaw models. We then turn to the discussion of the cases when the asymmetry is generated in the context of seesaw models extended with flavor symmetries, before or after flavor symmetry breaking. Finally we explain how the interplay between type-I and type-II seesaws can (or not) lead to viable models for leptogenesis even when there is an exact mixing pattern enforced by the flavor symmetry.
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Probing Lepton Flavor Triality with Higgs Boson Decay

Probing Lepton Flavor Triality with Higgs Boson Decay

FIG. 5: Discovery potential of H compared to the SM Higgs boson in the W W mode at 7 TeV with an integrated luminosity of 1 fb −1 : (a) ATLAS and (b) CMS for f 1 = 02; (c) ATLAS and (d) CMS for f 1 = 0.5. lepton flavor symmetry predicted by non-Abelian discrete symmetries, such as A4, T7, and ∆(27), which explain successfully the observed pattern of neutrino tribimaximal mixing. The

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Probing the scotogenic model with lepton flavor violating processes

Probing the scotogenic model with lepton flavor violating processes

JHEP02(2015)144 space [ 3 ]. The scotogenic model thus provides the perfect scenario to assess the impact of future lepton flavor violation experiments. Lepton flavor violation in the scotogenic model has already been studied in some detail. Early works, including [ 4 – 7 ], focused almost exclusively on µ → eγ, due to its stringent ex- perimental limit. Other processes, such as µ → 3 e or µ-e conversion in nuclei, were rarely considered, and when they were so, only the photonic dipole contribution was taken into account. This situation was recently remedied in [ 3 ], where complete analytical expressions for the most important lepton flavor violating (LFV) processes were obtained. But a thor- ough analysis of lepton flavor violation in this model including the constraints from the dark matter density and the expected improvements in LFV experiments was yet to be done.
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Collider aspects of flavor physics at high Q

Collider aspects of flavor physics at high Q

2.4.2 A Case Study If the fourth family is primarily mixing with the first two families, the dominant decay channels will be t ′ → W + s(d) and b ′ → W − c(u). In this case, since the light quark jets are indistinguishable, the signature will be W + W − j j for both t ′ t ¯ ′ and b ′ b ¯ ′ pair production. According to flavour democracy, the masses of the new quarks have to be within few GeV of each other. This is also experimentally hinted by the value of the ρ parameter’s value which is close to unity [49]. For such a mixing, both up and down type new quarks should be considered together since distinguishing between t ′ and b ′ quarks with quasi-degenerate masses in a hadron collider seems to be a difficult task. Moreover, the tree level pair production and decay diagrams of the new b ′ quarks are also valid for the t ′ quark, provided c, u is replaced by s, d. As the model is not able to predict the masses of the new quarks, three mass values (250, 500 and 750 GeV) are considered as a mass scan. The widths of the b ′ and t ′ quarks are proportional to |V b ′ u | 2 + |V b ′ c | 2 and |V t ′ d | 2 + |V t ′ s | 2 respectively. Current upper limits for corresponding CKM matrix elements are |V b ′ u | < 0.004, |V b ′ c | < 0.044, |V t ′ d | < 0.08 and |V t ′ s | < 0.11. For the present case study, the common value 0.001 is used for all four elements. As the widths of the new quarks are much smaller than 1 GeV, this selection of the new CKM elements has no impact on the calculated cross sections. Table 4.5 gives the cross section for the b ′ b ¯ ′ or t ′ t ¯ ′ production processes which are within 1s% of each other as expected. For this reason, from this point on, b ′ will be considered and the results will be multiplied by two to cover both t ′ and b ′ cases. Therefore in the final plots, the notation q 4 is used to cover both t ′ and b ′ .
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On non-exponential stability of delay systems of neutral type with non-singular neutral term

On non-exponential stability of delay systems of neutral type with non-singular neutral term

tions// volume 99 of Applied Mathematical Sciences, Springer-Verlag, New York – 1993. [8] R. Rabah, G. M. Sklyar, and P. Yu. Barkhayev. Stability analysis of mixed retarded-neutral type systems, Preprint IRCCyN, Nantes, RI2008_8, 2008. [9] Rabah R., Sklyar G. M., Rezounenko A. V. On strong regular stabilizability for linear neutral type systems, J. Differential Equations 45 (2008), No. 3, 569–593.

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Savage's Theorem Under Changing Awareness

Savage's Theorem Under Changing Awareness

9 Concluding remarks I have presented a unified framework and theorem for preferences under uncertainty and changing awareness. Preferences are governed by expected utility with three rules for revising utilities and probabilities as awareness changes. The theorem has many special cases, including (i) fixed awareness, where we recover Savage’s Theorem, (ii) fixed outcome awareness, where utilities are stable, (iii) fixed state awareness, where probabilities are stable, (iv) exhaustive state awareness, where some key definitions simplify, and (v) fine state awareness, where Axiom 6 and the third revision rule simplify. Just as Savage’s axioms have been weakened over time, giving rise to ‘non-EU’ theories, it would be interesting to relax the current axioms and explore ‘less rational’ representations and revision rules.
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A Changing Idea of Justice

A Changing Idea of Justice

I am delighted that at the Canadian Centre for Victims of Torture (CCVT), I have found my full identity as a human rights activist, a refugee, a survivor of torture, an educator and[r]

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Policy Implications of Changing Longevity

Policy Implications of Changing Longevity

E-mail: gregory.ponthiere@ens.fr Abstract 5 Our societies are witnessing a steady increase in longevity. This demographic evolution is accompanied by some convergence across countries, whereas substantial longevity inequalities persist within nations. The goal of this article is to survey some crucial impli- cations of changing longevity on the design of optimal public policy. For that purpose, we first focus on some difficulties raised by risky and varying lifetime for the representation of

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The Changing Face of Retirement

The Changing Face of Retirement

current hIgh retIrement rePlacement IncomeS do not create a SenSe oF readIneSS among current workForce employees in the United Kingdom, the United States and Germany all show high levels[r]

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CP violation in flavor-tagged Bs̳ --> J/[psi][phi] decays

CP violation in flavor-tagged Bs̳ --> J/[psi][phi] decays

Rather than providing a full theoretical description or an exhaustive catalogue of experimental tests of Standard Model weak processes, we describe in this section [r]

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Measurement of $B_d$ mixing using opposite-side flavor tagging

Measurement of $B_d$ mixing using opposite-side flavor tagging

The B 0 d meson flavor at its production can be identified using information from the reconstructed side or from the opposite side (see Fig. 1). One can tag the flavor using charge correlation between “fragmentation tracks” associated with the reconstructed B meson. Such corre- lations were first observed in e + e − → Z 0 → b¯b events by the OPAL experiment [2]. This is known as “same-side flavor tagging.” The flavor can also be inferred from the decay information of the second B meson in the event, assuming that b and ¯b are produced in pairs, and thus in the ideal case, the two mesons have opposite flavors. This method is known as “opposite-side flavor tagging.” An advantage of the latter method is that its performance should be independent of the type of the reconstructed B meson.
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