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53,162
result(s) for
"PHYSICS OF ELEMENTARY PARTICLES AND FIELDS"
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Vector boson pair production at the LHC
by
Williams, Ciaran
,
Campbell, John M.
,
Ellis, R. Keith
in
Classical and Quantum Gravitation
,
Elementary Particles
,
Gluons
2011
We present phenomenological results for vector boson pair production at the LHC, obtained using the parton-level next-to-leading order program MCFM. We include the implementation of a new process in the code,
pp
→
γγ
, and important updates to existing processes. We incorporate fragmentation contributions in order to allow for the experimental isolation of photons in
γγ
,
Wγ
, and
Zγ
production and also account for gluon-gluon initial state contributions for all relevant processes. We present results for a variety of phenomenological scenarios, at the current operating energy of
TeV and for the ultimate machine goal,
TeV. We investigate the impact of our predictions on several important distributions that enter into searches for new physics at the LHC.
Journal Article
Gluon-gluon contributions to W+W− production and Higgs interference effects
by
Williams, Ciaran
,
Campbell, John M.
,
Ellis, R. Keith
in
AMPLITUDES
,
Classical and Quantum Gravitation
,
DECAY
2011
In this paper we complete our re-assessment of the production of
W
boson pairs at the LHC, by calculating analytic results for the
process including the effect of massive quarks circulating in the loop. Together with the one-loop amplitudes containing the first two generations of massless quarks propagating in the loop, these diagrams can give a significant contribution with a large flux of gluons. One of the component parts of this calculation is the production of a standard model Higgs boson,
gg
→
H
and its subsequent decay,
. We will quantify the importance of the interference between the Higgs boson production process and the gluon-induced continuum production in the context of searches for the Higgs boson at the Tevatron and the LHC. For instance, for
m
H
< 140 GeV the effect of the interference typically results in around a 10% reduction in the expected number of Higgs signal events. The majority of this interference is due to non-resonant contributions. Therefore cuts on the transverse mass such as those currently used by the ATLAS collaboration reduce the destructive interference to about a 1% effect. We advocate that a cut on the maximum transverse mass be used in future Higgs searches in this channel.
Journal Article
Low energy analysis techniques for CUORE
2017
CUORE is a tonne-scale cryogenic detector operating at the Laboratori Nazionali del Gran Sasso (LNGS) that uses tellurium dioxide bolometers to search for neutrinoless double-beta decay of
130
Te. CUORE is also suitable to search for low energy rare events such as solar axions or WIMP scattering, thanks to its ultra-low background and large target mass. However, to conduct such sensitive searches requires improving the energy threshold to 10 keV. In this paper, we describe the analysis techniques developed for the low energy analysis of CUORE-like detectors, using the data acquired from November 2013 to March 2015 by CUORE-0, a single-tower prototype designed to validate the assembly procedure and new cleaning techniques of CUORE. We explain the energy threshold optimization, continuous monitoring of the trigger efficiency, data and event selection, and energy calibration at low energies in detail. We also present the low energy background spectrum of CUORE-0 below
60
keV
. Finally, we report the sensitivity of CUORE to WIMP annual modulation using the CUORE-0 energy threshold and background, as well as an estimate of the uncertainty on the nuclear quenching factor from nuclear recoils inCUORE-0.
Journal Article
Toward holographic reconstruction of bulk geometry from lattice simulations
by
Rinaldi, Enrico
,
Hanada, Masanori
,
Berkowitz, Evan
in
ASTRONOMY AND ASTROPHYSICS
,
Black holes
,
Black Holes in String Theory
2018
A
bstract
A black hole described in SU(
N
) gauge theory consists of
N
D-branes. By separating one of the D-branes from others and studying the interaction between them, the black hole geometry can be probed. In order to obtain quantitative results, we employ the lattice Monte Carlo simulation. As a proof of the concept, we perform an explicit calculation in the matrix model dual to the black zero-brane in type IIA string theory. We demonstrate this method actually works in the high temperature region, where the stringy correction is large. We argue possible dual gravity interpretations.
Journal Article
Electron performance measurements with the ATLAS detector using the 2010 LHC proton-proton collision data
by
Petteni, M.
,
Tic, T.
,
Walkowiak, W.
in
Astronomy
,
Astrophysics and Cosmology
,
Collisions (Nuclear physics)
2012
Detailed measurements of the electron performance of the ATLAS detector at the LHC are reported, using decays of the
Z
,
W
and
J
/
ψ
particles. Data collected in 2010 at
are used, corresponding to an integrated luminosity of almost 40 pb
−1
. The inter-alignment of the inner detector and the electromagnetic calorimeter, the determination of the electron energy scale and resolution, and the performance in terms of response uniformity and linearity are discussed. The electron identification, reconstruction and trigger efficiencies, as well as the charge misidentification probability, are also presented.
Journal Article
Gauged and ungauged: a nonperturbative test
by
Rinaldi, Enrico
,
Hanada, Masanori
,
Berkowitz, Evan
in
Classical and Quantum Gravitation
,
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
,
Computer simulation
2018
A
bstract
We study the thermodynamics of the ‘ungauged’ D0-brane matrix model by Monte Carlo simulation. Our results appear to be consistent with the conjecture by Maldacena and Milekhin.
Journal Article
Feebly-interacting particles: FIPs 2022 Workshop Report
by
Dandoy, V.
,
Ulmer, S.
,
Gatti, C.
in
Astronomy
,
Astrophysics and Cosmology
,
Conferences, meetings and seminars
2023
Particle physics today faces the challenge of explaining the mystery of dark matter, the origin of matter over anti-matter in the Universe, the origin of the neutrino masses, the apparent fine-tuning of the electro-weak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves new physics at mass scales comparable to familiar matter, below the GeV-scale, or even radically below, down to sub-eV scales, and with very feeble interaction strength. New theoretical ideas to address dark matter and other fundamental questions predict such feebly interacting particles (FIPs) at these scales, and indeed, existing data provide numerous hints for such possibility. A vibrant experimental program to discover such physics is under way, guided by a systematic theoretical approach firmly grounded on the underlying principles of the Standard Model. This document represents the report of the FIPs 2022 workshop, held at CERN between the 17 and 21 October 2022 and aims to give an overview of these efforts, their motivations, and the decadal goals that animate the community involved in the search for FIPs.
Journal Article
Supernova 1987A constraints on sub-GeV dark sectors, millicharged particles, the QCD axion, and an axion-like particle
by
Essig, Rouven
,
McDermott, Samuel D.
,
Chang, Jae Hyeok
in
ASTRONOMY AND ASTROPHYSICS
,
Atoms & subatomic particles
,
Beyond Standard Model
2018
A
bstract
We consider the constraints from Supernova 1987A on particles with small couplings to the Standard Model. We discuss a model with a fermion coupled to a dark photon, with various mass relations in the dark sector; millicharged particles; dark-sector fermions with inelastic transitions; the hadronic QCD axion; and an axion-like particle that couples to Standard Model fermions with couplings proportional to their mass. In the fermion cases, we develop a new diagnostic for assessing when such a particle is trapped at large mixing angles. Our bounds for a fermion coupled to a dark photon constrain small couplings and masses ≲ 200 MeV, and do not decouple for low fermion masses. They exclude parameter space that is otherwise unconstrained by existing accelerator-based and direct-detection searches. In addition, our bounds are complementary to proposed laboratory searches for sub-GeV dark matter, and do not constrain several benchmark-model targets in parameter space for which the dark matter obtains the correct relic abundance from interactions with the Standard Model. For a millicharged particle, we exclude charges between 10
−9
–few×10
−6
in units of the electron charge, also for masses ≲ 200 MeV; this excludes parameter space to higher millicharges and masses than previous bounds. For the QCD axion and an axion-like particle, we apply several updated nuclear physics calculations and include the energy dependence of the optical depth to accurately account for energy loss at large couplings. These corrections allow us to rule out a hadronic axion of mass between 0.1 and a few hundred eV, or equivalently to put a bound on the scale of Peccei-Quinn symmetry breaking between a few×10
4
and 10
8
GeV, closing the hadronic axion window. For an axion-like particle, our bounds disfavor decay constants between a few×10
5
GeV up to a few×10
8
GeV, for a mass ≲ 200 MeV. In all cases, our bounds differ from previous work by more than an order of magnitude across the entire parameter space. We also provide estimated systematic errors due to the uncertainties of the progenitor.
Journal Article
UFO 2.0: the ‘Universal Feynman Output’ format
by
Schumann, Steffen
,
Shao, Hua-Sheng
,
Mattelaer, Olivier
in
Approximation
,
Astronomy
,
Astrophysics and Cosmology
2023
We present an update of the
Universal FeynRules Output
model format, commonly known as the UFO format, that is used by several automated matrix-element generators and high-energy physics software. We detail different features that have been proposed as extensions of the initial format during the last ten years, and collect them in the current second version of the model format that we coin the
Universal Feynman Output
format. Following the initial philosophy of the UFO, they consist of flexible and modular additions to address particle decays, custom propagators, form factors, the renormalisation group running of parameters and masses, and higher-order quantum corrections.
Journal Article