ترغب بنشر مسار تعليمي؟ اضغط هنا

Collider Signals of Maximal Flavor Violation: Same-Sign Leptons from Same-Sign Tops at the Tevatron

363   0   0.0 ( 0 )
 نشر من قبل Daniel Whiteson
 تاريخ النشر 2008
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

In models of maximal flavor violation (MxFV) there is at least one new scalar $Phi_{FV}$ which couples to the quarks via $Phi_{FV} q_i q_j propto xi_{ij}$ where $xi_{i3},xi_{3i} sim V_{tb}$ for $i = 1,2$ and $xi_{33} sim V_{td}$ and $V$ is the CKM matrix. In this article, we explore the potential phenomenological implications of MxFV for collider experiments. We study MxFV signals of same-sign leptons from same-sign top-quark pair production at the Tevatron and at the LHC. We show that the current Tevatron dataset has strong sensitivity to this signature, for which there are no current limits. For example, if $m_{Phi_{FV}} sim 200$ GeV and the MxFV coupling $xi$ has a natural value of $sim 1$, we expect $sim 12$ MxFV events to survive a selection requiring a pair of same-sign leptons, a tagged $b$-jet and missing transverse energy, over a background of approximately 4-5 events.



قيم البحث

اقرأ أيضاً

In supersymmetric models with light higgsinos (which are motivated by electroweak naturalness arguments), the direct production of higgsino pairs may be difficult to search for at LHC due to the low visible energy release from their decays. However, the wino pair production reaction tw_2^pmtz_4to (W^pmtz_{1,2})+(W^pmtw_1^mp) also occurs at substantial rates and leads to final states including equally opposite-sign (OS) and same-sign (SS) diboson production. We propose a novel search channel for LHC14 based on the SS diboson plus missing E_T final state which contains only modest jet activity. Assuming gaugino mass unification, and an integrated luminosity > 100 fb^{-1}, this search channel provides a reach for SUSY well beyond that from usual gluino pair production.
We study the polarization of positively charged $W$s in the scattering of massive electroweak bosons at hadron colliders. We rely on the separation of weak boson polarizations in the gauge-invariant, doubly-resonant part of the amplitude in Monte Car lo simulations. Polarizations depend on the reference frame in which they are defined. We discuss the change in polarization fractions and in kinematic distributions arising from defining polarization vectors in two different reference frames which have been employed in recent experimental analyses.
The top quark is the heaviest known elementary particle of the Standard Model (SM) of particle physics and, therefore, it is expected to have large couplings to hypothetical new physics in many models beyond the SM (BSM). Various studies have predict ed the presence of multi-lepton anomalies at the LHC. One of those anomalies is the excess production of two same-sign leptons and three isolated leptons in association with $b$-jets. These are reasonably well described by a 2HDM+$S$ model, where $S$ is a singlet scalar. Both the ATLAS and CMS experiments have reported sustained excesses in these final states. This includes corners of the phase-space where production of top quark pairs in association with a $W$ boson contributes to. Here, we investigate the production of two same-sign and three leptons from the production of four top quark final states. Our focus is on understanding the differences between the SM and BSM production mechanisms of four top quarks from $toverline{t} A$ ($A rightarrow toverline{t}$) using Machine Leaning techniques with twelve discriminating kinematic variables.
We study in detail the collider signatures of an $SU(2)_R$ fermionic quintuplet in the framework of left-right symmetric model in the context of the 13 TeV LHC. Apart from giving a viable dark matter candidate ($chi^0$), this model provides unique co llider imprints in the form of same-sign multileptons through the decays of multi-charged components of the quintuplet. In particular, we consider the scenario where the quintuplet carries $(B - L) = 4$ charge, allowing for the presence of high charge-multiplicity particles with relatively larger mass differences among them compared to $(B - L)$ = 0 or 2. In this paper, we mainly focus on the same-sign n-lepton signatures (nSSL). We show that with an integrated luminosity of 500 $fb^{-1}$, the mass of the neutral component, $M_{chi^0} leq 480~(800)$ GeV can be excluded at 95% CL in the 2SSL (3SSL) channel after imposing several selection criteria. We also show that a $5sigma$ discovery is also achievable if $M_{chi^0} leq 390~(750)$ GeV in the 2SSL (3SSL) channel with 1000 $fb^{-1}$ integrated luminosity.
The future runs of LHC offer a unique opportunity to measure correlations between two partons inside the proton, which have never been experimentally detected. The process of interest is the production of two positively charged W-bosons decaying in t he muon channel. We present a detailed analysis of proton-proton collisions at $sqrt{s}$ = 13 TeV, where we combine Monte Carlo event generators with our calculations of parton correlations. We carefully compare double parton scattering to relevant background processes and trace a path towards a clean signal sample. Several observables are constructed to demonstrate the effect of parton correlations with respect to clear benchmark values for uncorrelated scatterings. We find that especially spin correlations can be responsible for large effects in the variables we study, because of their direct relation with the parton angular momentum and, therefore, the directions of the muon momenta. We estimate the significance of the measurements as a function of the integrated luminosity and conclude that the LHC has the potential to detect, or put strong limits on, parton correlations in the near future.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا