EF04 Topical Group Community Meeting

US/Eastern
Description

Connect through Zoom: https://cern.zoom.us/j/95541369778

Meeting ID: 955 4136 9778

Password: Ask coordinators

MC issue: suggestion is to run analysis on EOS samples in lxplus, run same code in snowmass machine, copy outputs to same machine

Marc-Andre: talk in 2 weeks, will show workflow for validation

Graham Wilson - Measuring center-of-mass energy and momentum scale for precision EW physics at future e+e-colliders
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dilepton method: sqrt(s_p) as sqrt(s) estimator (ties detector p scale to particle mass scales - J/psi known to 1.9ppm)

center-of-mass energy issues
sqrt(s_p) uses only lepton momenta; critical part: tracker momentum scale; use KS, Lambda, J/psi...

today: sqrt(s_p) method w/ mu+mu-
overview of new concept in recent tracker momentum scale studies

in progress: ISR/FSR

dimuons in low, medium, high mass (boundary: 50 and 150GeV)
back to back events in full energy peak; significant radiative return (ISR) to Z and to low mass

s_p method: assume beams have equal energy; lab is CM frame; dimuon recoil against massless system

LCWS2021 talk about Armenteros-Podolanski kinematic construction for 2-body decays and usage in measuring tracker momentum scale
explore AP method on KS, more statistics than J/psi
big help in Z precision studies

KS, Lambda: can get improvements by factor 50-70 on PDG

more realistic: focus estimate central mass energy of e+e- after shower
e+e- energy at truth level after beamstrahlung: would give distribution of sqrt(s) and initial state momentum vector (in particular, z component)
fit positron beam energy after beamstrahlung; width dominated by beam energy spread

final state kinematics: look at e+e- -> mu+mu-(gamma)
rest of event (RoE) is system 3, the muons are particles 1 and 2
RoE may not be fully detected, have 4 equations and 5 unknowns
use averaged beam energy quadratic
consider three cases: 0 crossing angle, equal beam energies... get formula shown before

large fraction of difference is due to lower mass part?

event selection requirements, based on ILD simulation
require sqrt(s_p) uncertainty <0.8% based on propagating track-based matrices
dimuon passes vertex fit w/ >1% p-value

background small (e.g., tautau is 0.15%?), not yet studied in detail

pull distributions look fine

vertex fit: exploit ILC nanobeam

look at gold quality vs silver vs bronze quality events (classified by sqrt(s_p) uncertainty value)
fit center-of-mass energy estimate with Crystal Ball

measuring mZ w/ high-energy running
main systematics: momentum scale, FSR, electron channel momentum scale (more difficult)
more sensitive to Z mass at 250GeV

LOI has 3 thrusts, progress on two, space for students!

progress: new high precision method for momentum-scale; detailed study of dimuon
measurement of mZ with dimuon mass >>mZ

Ayres: gold, silver, bronze: are these events from same sample, put in different categories. Is categorization done in experiment too, or done here for illustration?
GW: did this as a starting point for fit that includes uncertainties (binned in three rather than individual?)

Junping: sqrt(s_p) works for events limited to 1 photon, what if there are more (and are in different direction)?
GW: there is attempt at looking at this

Mayuri Kawale - VBS at Future Colliders
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study aQGC in dim-8
VBS processes: mu+mu- -> WWnunu

MadGraph and Whizard samples generated

working on validation of the MC samples

plan: repeat studies for 3, 10, 30TeV

note: mu+mu- -> WWmu+mu- has WWGG QGC vertex: signal or background?

Ayres: logic in picking dim-8: is that dim-6 assumed to be constrained by LHC, or that there are models that only affect dim-8?
Aram Apyam: so far going with this setup; there is also issue of validity of EFT at high energy

Roberto Petti - Precision measurements at LBNF
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new neutrino beam
standard option for CP, and optimized (higher E) for nu_tau appearance
5ton detector, expect 1e8 charged-current events
one of three detectors is permanently on the beam axis: SAND
LOI is about SAND
straw-tube tracker (STT) to control nu target
thin films of high chemical purity material
proposal for solid hydrogen target: obtained by subtracting C (graphite) from CH2 (subtract the spectra of particles): obtain something equivalent to 10m^3 of liquid 
hydrogen underground, which is technically not possible (danger)

STT, proposed in LOI, has been chosen as part of SAND, and will be built over next years
physics program described in LOI will become reality

idea is to reduce systematics by reducing precision gap with electron experiment (relative neutrino fluxes and energy need to be known to <1%)

lots of physics:
sin mixing angle; isospin and sum rules; strangeness in proton; QCD; nuclear physics and neutrino interactions; BSM
note: this experiment designed for neutrino oscillations!

not much recent progress on EWK physics studies (focus was on detector)
example of low-energy EWK measurement: direct measurement of neutrino couplings to Z (only measurement of Gamma_nunu); single experiment to directly check running of 
mixing angle

Ayres: what kind a studies and sensitivities expect by next year?
RP: useful to study specific details of channel vs exposure

AF: about combinations: considering using SMEFT framework, to combine with others? then just need to worry about providing correlation matrices

Junping: one of measurements here of interest for EFT is neutrino-electron elastic scattering
RP: fiducial mass of detector is small (5ton), channel limited by statistic; however, will have small systematic uncertainty due to low background of selection (~5% in 
proton; in DUNE, have much larger fiducial mass, but backgrounds are ~14%) and high resolution
high beam option could increase statistics

perfectly isoscalar target, and calibration with proton-free target at the same time can help disentangle anomalies
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