This poster outlines searches by the CMS Collaboration for three beyond-standard-model candidates: Z' bosons from E6 and sequential standard models, and large extra dimensions. Events with two taus decaying to an electron and muon are selected to exploit the cleanest decay channel while mitigating large standard model backgrounds. No significant excesses are observed in the visible mass distribution, allowing lower mass limits to be set excluding Z' masses below 1.1-1.4 TeV and scales of large extra dimensions below 1.6-4.4 TeV depending on the model.
Poster of my master\'s research presented at the Physics@FOM conference at Veldhoven on 20 januari 2010. There\'s one error in the equations, can you find it?
I show how much GW corrections are important not only for the band structure but also in the calculation of the electron-phonon matrix elements. I present different examples and comparison with the experimental results.
Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of el...Sérgio Sacani
High-energy cosmic-ray electrons and positrons (CREs), which
lose energy quickly during their propagation, provide a probe of
Galactic high-energy processes1–7 and may enable the observation
of phenomena such as dark-matter particle annihilation or
decay8–10. The CRE spectrum has been measured directly up to
approximately 2 teraelectronvolts in previous balloon- or spaceborne
experiments11–16, and indirectly up to approximately 5
teraelectronvolts using ground-based Cherenkov γ-ray telescope
arrays17,18. Evidence for a spectral break in the teraelectronvolt
energy range has been provided by indirect measurements17,18,
although the results were qualified by sizeable systematic
uncertainties. Here we report a direct measurement of CREs in the
energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the
Dark Matter Particle Explorer (DAMPE)19 with unprecedentedly
high energy resolution and low background. The largest part of
the spectrum can be well fitted by a ‘smoothly broken power-law’
model rather than a single power-law model. The direct detection of
a spectral break at about 0.9 teraelectronvolts confirms the evidence
found by previous indirect measurements17,18, clarifies the behaviour
of the CRE spectrum at energies above 1 teraelectronvolt and sheds
light on the physical origin of the sub-teraelectronvolt CREs.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
Poster of my master\'s research presented at the Physics@FOM conference at Veldhoven on 20 januari 2010. There\'s one error in the equations, can you find it?
I show how much GW corrections are important not only for the band structure but also in the calculation of the electron-phonon matrix elements. I present different examples and comparison with the experimental results.
Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of el...Sérgio Sacani
High-energy cosmic-ray electrons and positrons (CREs), which
lose energy quickly during their propagation, provide a probe of
Galactic high-energy processes1–7 and may enable the observation
of phenomena such as dark-matter particle annihilation or
decay8–10. The CRE spectrum has been measured directly up to
approximately 2 teraelectronvolts in previous balloon- or spaceborne
experiments11–16, and indirectly up to approximately 5
teraelectronvolts using ground-based Cherenkov γ-ray telescope
arrays17,18. Evidence for a spectral break in the teraelectronvolt
energy range has been provided by indirect measurements17,18,
although the results were qualified by sizeable systematic
uncertainties. Here we report a direct measurement of CREs in the
energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the
Dark Matter Particle Explorer (DAMPE)19 with unprecedentedly
high energy resolution and low background. The largest part of
the spectrum can be well fitted by a ‘smoothly broken power-law’
model rather than a single power-law model. The direct detection of
a spectral break at about 0.9 teraelectronvolts confirms the evidence
found by previous indirect measurements17,18, clarifies the behaviour
of the CRE spectrum at energies above 1 teraelectronvolt and sheds
light on the physical origin of the sub-teraelectronvolt CREs.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
Excitons, lifetime and Drude tail within the current~current response framew...Claudio Attaccalite
We compare the optical absorption of extended systems calculated starting from the density-density and current-current linear response formalisms within the equilibrium many-body perturbation theory(MBPT). We show how, using the latter, one can incur in errors due to quasiparticle lifetimes, electron-hole interaction or the presence of a Drude tail. We present a solution for each one of these problems.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
Systematic Study Multiplicity Production Nucleus – Nucleus Collisions at 4.5 ...IOSRJAP
The correlations between the multiplicity distributions and the projectile fragments, as well as the correlation between the black and grey fragments were given. We observed that the mean number of interacting projectile nucleons increases quickly as the value of heavily ionizing charged particles increase as expected but attains a more or less constant value for extreme central collisions. Finally, there is no distinct correlation between the shower particle production and the target excitation, but the average value of grey particles decreases with the increase of the number of black particles and vice versa. This correlation can also be explained by the fireball model.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
An alternative way to calculate spin ground state of organometallic complexes. Shown for more than one metallic centers and complex formalism, For more please feel free to mail me.
Convergence Behaviour of Newton-Raphson Method in Node- and Loop-Based Non-li...balaganesh boomiraja
A simplified Jacobian is derived for both node- and loop-based magnetic equivalent circuit analysis. The partial derivative term is eliminated in this simplified Jacobian using differential relative permeability. The convergence behaviour of the Newton-Raphson method is studied. The loop analysis exhibits more stable convergence than that of the node analysis while solving non-linear magnetic equivalent circuit using the Newton-Raphson method.
Excitons, lifetime and Drude tail within the current~current response framew...Claudio Attaccalite
We compare the optical absorption of extended systems calculated starting from the density-density and current-current linear response formalisms within the equilibrium many-body perturbation theory(MBPT). We show how, using the latter, one can incur in errors due to quasiparticle lifetimes, electron-hole interaction or the presence of a Drude tail. We present a solution for each one of these problems.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
Systematic Study Multiplicity Production Nucleus – Nucleus Collisions at 4.5 ...IOSRJAP
The correlations between the multiplicity distributions and the projectile fragments, as well as the correlation between the black and grey fragments were given. We observed that the mean number of interacting projectile nucleons increases quickly as the value of heavily ionizing charged particles increase as expected but attains a more or less constant value for extreme central collisions. Finally, there is no distinct correlation between the shower particle production and the target excitation, but the average value of grey particles decreases with the increase of the number of black particles and vice versa. This correlation can also be explained by the fireball model.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
An alternative way to calculate spin ground state of organometallic complexes. Shown for more than one metallic centers and complex formalism, For more please feel free to mail me.
Convergence Behaviour of Newton-Raphson Method in Node- and Loop-Based Non-li...balaganesh boomiraja
A simplified Jacobian is derived for both node- and loop-based magnetic equivalent circuit analysis. The partial derivative term is eliminated in this simplified Jacobian using differential relative permeability. The convergence behaviour of the Newton-Raphson method is studied. The loop analysis exhibits more stable convergence than that of the node analysis while solving non-linear magnetic equivalent circuit using the Newton-Raphson method.
We perform a global QCD analysis of high energy scattering data within the
JAM Monte Carlo framework, including a coupling to a dark photon that augments the
Standard Model (SM) electroweak coupling via kinetic mixing with the hypercharge B
boson. We first set limits on the dark photon mass and mixing parameter assuming that
the SM is the true theory of Nature, taking into account also the effect on g − 2 of the
muon. If instead we entertain the possibility that the dark photon may play a role in
deep-inelastic scattering (DIS), we find that the best fit is preferred over the SM at 6.5 ,
even after accounting for missing higher order uncertainties. The improvement in 2 with
the dark photon is stable against all the tests we have applied, with the improvements in the
theoretical predictions spread across a wide range of x and Q2. The largest improvement
corresponds to the fixed target and HERA DIS data, while the best fit yields a value of g−2
which significantly reduces the disagreement with the latest experimental determination.
Forming intracluster gas in a galaxy protocluster at a redshift of 2.16Sérgio Sacani
Galaxy clusters are the most massive gravitationally bound structures in the Universe, comprising thousands of galaxies and
pervaded by a diffuse, hot “intracluster medium” (ICM) that dominates the baryonic content of these systems. The formation
and evolution of the ICM across cosmic time1
is thought to be driven by the continuous accretion of matter from the large-scale
filamentary surroundings and dramatic merger events with other clusters or groups. Until now, however, direct observations of
the intracluster gas have been limited only to mature clusters in the latter three-quarters of the history of the Universe, and we
have been lacking a direct view of the hot, thermalized cluster atmosphere at the epoch when the first massive clusters formed.
Here we report the detection (about 6σ) of the thermal Sunyaev-Zeldovich (SZ) effect2
in the direction of a protocluster. In fact,
the SZ signal reveals the ICM thermal energy in a way that is insensitive to cosmological dimming, making it ideal for tracing
the thermal history of cosmic structures3
. This result indicates the presence of a nascent ICM within the Spiderweb protocluster
at redshift z = 2.156, around 10 billion years ago. The amplitude and morphology of the detected signal show that the SZ
effect from the protocluster is lower than expected from dynamical considerations and comparable with that of lower-redshift
group-scale systems, consistent with expectations for a dynamically active progenitor of a local galaxy cluster.
Electrostatic Edge Plasma Turbulence in the Uragan-3M torsatron
Tau14_7TeV
1. Motivation: The Standard Model (SM) of elementary particle physics has been tremendously successful at describing high energy physics phenomena, but it remains incomplete. Several beyond-standard-model (BSM) theories
introduce extra gauge bosons, many with generation-dependent lepton couplings. It is worthwhile to study the ditau decay channels of these additional gauge bosons as it could lead to new physics and tests of lepton universality.
This poster outlines a search for two such heavy gauge boson candidates as well as one candidate motivated by a model of large extra dimensions.
Search for Z’ → ττ → eμ and Large Extra Dimensions with Two Taus at 𝑠 = 8 TeV
The CMS Collaboration
F. Romeo, A. Santocchia, A. Gurrola, W. Johns, P. Sheldon, A. Johnson, J. Cumalat, E. Luiggi, T. Kamon, A. Florez, A. Kaur Kalsi, J.B. Singh, V. Bhatnagar, and K. Mazumdar
Z’-like resonances
E6 Model
E6 → SO(10)xU(1)ψ → SU(5)xU(1)χxU(1)ψ → SMxU(1)θE6
U(1)θE6
→ Z’(θE6
) : cos(θE6
)Z’ψ - sin(θE6
)Z’χ
θE6
ϵ (-90°, 90°) : θE6
= 0 → Z’ψ , θE6
= -90° → Z’χ
Exclude on Z’ψ
Sequential Standard Model
Z’SSM identical to SM Z, only heavier
Not gauge invariant
Exclude on Z’ SSM
Arkani-Hamed, Dimopoulos and Divali (ADD) model
Introduced to solve hierarchy problem of SM
𝑀 𝑝𝑙
2
= 𝑀 𝐷
2+𝑛
× 𝑅 𝑛
𝑀 𝑝𝑙 = Plank scale, 𝑀 𝐷 = effective Plank scale, 𝑅 = size of extra dimensions
If 𝑀 𝐷 ~ O(1) TeV →𝑅 ≤ O(1) mm for n ≥ 2
ADD model includes infinite tower of Kaluza-Klein (𝑮 𝑲𝑲) excitations of gravitons
Direct graviton emission results in apparent non-conservation of momentum
(Suppressed by 𝑀 𝐷
2+𝑛
)
Virtual graviton couplings result in anomalous production of fermion-antifermion,
diboson pairs
Couplings depend weakly on n, higher sensitivity
Relevant parameters of ADD
𝜎𝑆𝑀+𝐿𝐸𝐷 = 𝜎𝑆𝑀 + 𝜎𝑖𝑛𝑡 𝜂 𝐺 + 𝜎 𝐺 𝜂 𝐺
2
int = interference, G = graviton, 𝜂 𝐺 =
1
Λ 𝑇
4 =
𝐹
𝑀 𝑆
4 = parameters regulating ADD
effects
𝑀𝑆 = UV cutoff on the sum of Kaluza-Klein excitations of virtual graviton exchange
Exclude on Λ 𝑇 in GRW, 𝑀𝑆 and n in HLZ conventions
Theory Analysis
Event Selection
Muons
Identified based on HighPt ID
convention
Global, small IP, small
∆𝑝𝑡
𝑝𝑡
𝐼 𝑃𝐹 =
𝑝 𝑇
𝑐ℎ𝑎𝑟𝑔𝑒𝑑
+max( 𝑝 𝑇
𝑛𝑒𝑢𝑡𝑟𝑎𝑙
+𝑝 𝑇
𝛾
−∆𝛽,0)
𝜇 𝑝 𝑇
Electrons
Identified using HEEP 4.1 selections
Optimized for high-pT electrons
Combination of track, ECAL, HCAL
requirements ensure clean electrons
Topological Selections
Require back to back electrons, muons
Opposite charge
0 b-tagged jets
ET > 20 GeV
Cuts designed to exploit collinearity of τ
decay products
Analysis Strategy
Blind signal region (SR) until understand BG mass shapes
Estimate BG contributions to SR via data-driven analysis (TTJets, QCD) or take
from MC with scale factor (diboson, DYJets, WJets)
Study visible mass (e, μ, ET) distributions for signal and BG
Unblind once we understand shapes, set limits on signal mass
Data-Driven Background
Estimation
MC models not perfect descriptors of
physics/detector, lack statistics
Would like to estimate BGs from data
Strategy: define controls regions (CRs) to
enhance BGs, examine cut performance
for data in CRs
Use cut efficiencies in CRs to estimate BG
contribution to data in SR
Other Backgrounds
For diboson, DYJets: define CR for BG,
measure scale factor (SF) between data
and MC in CR
Apply SF to MC in signal region to get BG
estimation for data in SR
For every BG, run a closure test:
compare estimated SR contribution to
MC SR contribution
Results
τ physics
Z’SSM expected to couple equally to pairs of electrons, muons,
taus (similar to SM Z)
Other beyond-standard-model theories predict generation-
dependent couplings favoring ditau decays
Worthwhile to study ditau decays as it could lead to new
physics, test lepton universality
eμ decay channel has small BR, but is the “cleanest”, and has the
highest reconstruction efficiency
Hadronic decay channels also being studied
ee, μμ channels not explored due to large DY background
Mass shape in Signal Region
Data observed in SR in agreement with SM
expectations for SR
No excesses observed
Set mass limit to exclude Z’-like resonances
below certain visible mass
Mass Limits on Z’-like resonances
Use Bayesian method for limit
extraction with flat prior for signal
cross section and log-normal priors
for systematic uncertainties
All tau decay channels combined for
final limits
Limits taken at 95% confidence level
Z’SSM excluded below 1.4 TeV
Z’ψ excluded below 1.1 TeV
Data and Monte Carlo
Data
Data were collected by CMS during the 2012 run of the Large Hadron Collider and
total 19.7 fb-1 of integrated luminosity
Background MC
Signal MC
Selection Cuts
All signal samples generated with PYTHIA. For Z’SSM and Z’ψ, tau decays simulated
with TAUOLA, and independent samples generated for different Z’ mass values (500
to 2500 GeV in 250 GeV intervals). For ADD model, independent samples generated
for different values of ΛT (1600 to 4400 GeV in 400 GeV intervals.)
SM background MC generated with POWHEG, MADGRAPH, and PYTHIA and
interfaced with TAUOLA to simulate tau decays. Significant backgrounds include:
𝒕 𝒕+Jets: typically has one or two b-tagged jets, produces real isolated leptons from W±
bosons from top decays
QCD: produces non-isolated jets that can fake leptons
Drell-Yan: can produce taus that mimic Z’ → ττ events. Low mass compared to signal
W+Jets: can produce clean muon from W ± decay, and jets can fake electrons
WW, WZ, ZZ: can produce real, isolated e’s and μ’s when bosons decay leptonically
tW: t can decay into W ±, then both W ± can decay leptonically
High-pT μ ID
HEEP v4.1
Results for the 8 TeV analysis are forthcoming, but not yet published .Below are the
results from the 7 TeV analysis, which was published in Phys. Lett. B 716 (2012) 82-
102. Note that it did not include searches for extra dimensions.
For more information, please see CMS-EXO-11-031 and CMS-EXO-12-046
Systematic Uncertainties
Statistical uncertainty of data used in CRs for
data driven BGs contributes large systematic
uncertainty to mass shape
Other systematics include those from object
energy scale and resolution, misidentified b-jets
pileup, luminosity, and theoretical sources (PDFs)