اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدProspects for the measurement of the $b$-quark mass at the ILC
102
0
0.0
(
0
)
تأليف
Juan Fuster
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
This note presents an analysis of the potential of future high-energy electron-positron colliders to measure the $b$-quark mass. We perform a full-simulation study of the measurement of the ratio of the three-jet rates in events with $bbar{b}(g)$ and $qbar{q}(g)$ production, $R_{3}^{bl}$, and assess the dominant uncertainties, including theory and experimental systematic uncertainties. We find that the ILC Higgs factory stage, with an integrated luminosity of 2 ab$^{-1}$ at $sqrt{s}=$ 250 GeV can measure the $b-$quark $bar{MS}$ mass at a scale of 250 GeV ($m_b(250~$GeV$)$) with a precision of 1 GeV. From this result we extrapolate the potential of the GigaZ run running at $sqrt{s}= m_Z$. We expect $m_b(m_Z)$ can be determined with an 0.12 GeV uncertainty, exceeding the precision of the LEP and SLD measurements by a factor $sim$3.
قيم البحث
اقرأ أيضاً
This paper describes an analysis performed at 250 GeV centre of mass energy for the reaction e+e- -> bbbar with the International Linear Collider, ILC, assuming an integrated luminosity of 500 fb-1. This measurement requires determining the b quark c
harge, which can be optimally performed using the precise micro-vertex detector of the detector ILD and the charged kaon identification provided by the dE/dx information of its TPC. Given that the forward backward asymmetry is maximal for e-L (Left-handed electron polarisation), it has been necessary to develop a new method to correct for unavoidable angular migration due to b charge mis-measurements. This correction is based on the reconstructed events themselves without introducing external corrections which would induce large uncertainties. With polarized beams, one can separate the Z and photon vector and axial couplings to b quarks. The precision reached is at the few per mill level, and should allow to confirm/discard the deviation observed at LEP1 on the ZbRbR coupling. Model independent upper bounds on the tensor couplings, F2V and F2A, are derived using the shape of the angular distribution.
Most supersymmetric models predict new particles within the reach of the next generation of colliders. For an understanding of the model structure and the mechanism(s) of electroweak symmetry breaking, it is important to know the masses of the new pa
rticles precisely. The measurement of the mass of the scalar partner of the top quark (stop) at an e+e- collider is studied. A relatively light stop is motivated by attempts to explain electroweak baryogenesis and can play an important role in dark matter annihilation. A method is presented which makes use of cross-section measurements near the pair-production threshold as well as at higher center-of-mass energies. It is shown that this method does not only increase the statistical precision, but also reduces the influence of systematic uncertainties, which can be important. Numerical results are presented, based on a realistic event simulation, for two signal selection strategies: using conventional selection cuts, and using an Iterative Discriminant Analysis (IDA). While the analysis of stops is particularly challenging due to the possibility of stop hadronization and fragmentation, the general procedure could be applied to many precision mass measurements.
The existence of dark matter has been established in astrophysics. However, there are no dark matter candidates in the Standard Model~(SM). If the dark matter particles or their mediator can not interact with SM fermions or gauge bosons, the Higgs bo
son is the only portal to the dark matter. We present a simulation study to search for invisible decays of the Higgs boson at the ILC with the ILD detector.
We study the $h gamma Z$ coupling, which is a loop induced coupling in the Standard Model (SM), to probe new physics. In a global fit based on the SM Effective Field Theory, measurement of the SM $h gamma Z$ coupling can provide a very useful constra
int, in particular for the precise determination of $hZZ$ and $hWW$ couplings. At the International Linear Collider (ILC), there are two direct ways to study the $h gamma Z$ coupling: one is to measure the branching ratio of the $h to gamma Z$ decay and the other to measure the cross section for the $e^+e^- to h gamma$ process. We have performed a full simulation study of the $e^+e^- to h gamma$ process at the 250 GeV ILC, assuming 2 ab$^{-1}$ data collected by the International Large Detector (ILD). The expected 1$sigma$ bound on the effective $hgamma Z$ coupling ($zeta_{AZ}$) combining measurements of the cross section for $e^+e^- to h gamma$ followed by $h to b bar{b}$ and the $h to gamma Z$ branching ratio is $-0.0015<zeta_{AZ}<0.0015$. The expected significance for the signal cross section in the fully hadronic $h to WW^*$ channel is 0.09 $sigma$ for beam polarizations of $P(e^-,e^+)=(-80%,+30%)$.
We studied the $e^+e^- to h gamma $ process at the International Linear Collider (ILC) at $sqrt{s}=250$ GeV, based on the full detector simulation of the International Large Detector (ILD). This process is loop-induced in the Standard Model (SM) and
is sensitive to new physics which alters $h gamma gamma$ or $h gamma Z$ coupling. We performed the analysis by employing the leading signal channels with $h to b bar{b}$ and $h to WW^*$ and including full SM background processes. The results are obtained for two scenarios of beam polarisations each with an integrated luminosity of 900 fb$^{-1}$. We found the expected significance of the SM signal is 0.40$sigma$ for $P(e^-,e^+)=(-0.8,+0.3)$ (the left-handed polarisation), and 0.06$sigma$ for $P(e^-,e^+)=(+0.8,-0.3)$ (the right-handed polarisation). The bounds on new physics effects are reported as the 95% C.L. upper limit for the cross-section of $e^+e^- to h gamma$: $sigma_{hgamma}^L <$ 1.8 fb and $sigma_{hgamma}^R <$ 0.5 fb respectively for left- and right-handed polarisations. The constraints on effective $hgamma Z$ couplings are to be further studied.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
