83,569 research outputs found
Precision Probes of QCD at High Energies
New physics, that is too heavy to be produced directly, can leave measurable
imprints on the tails of kinematic distributions at the LHC. We use energetic
QCD processes to perform novel measurements of the Standard Model (SM)
Effective Field Theory. We show that the dijet invariant mass spectrum, and the
inclusive jet transverse momentum spectrum, are sensitive to a dimension 6
operator that modifies the gluon propagator at high energies. The dominant
effect is constructive or destructive interference with SM jet production. We
compare differential next-to-leading order predictions from POWHEG to public 7
TeV jet data, including scale, PDF, and experimental uncertainties and their
respective correlations. We constrain a New Physics (NP) scale of 3.5 TeV with
current data. We project the reach of future 13 and 100 TeV measurements, which
we estimate to be sensitive to NP scales of 8 and 60 TeV, respectively. As an
application, we apply our bounds to constrain heavy vector octet colorons that
couple to the QCD current. We project that effective operators will surpass
bump hunts, in terms of coloron mass reach, even for sequential couplings.Comment: 40 pages, 13 figures, 8 tables. Minor changes. Accepted on JHE
Mixtures and products in two graphical models
We compare two statistical models of three binary random variables. One is a
mixture model and the other is a product of mixtures model called a restricted
Boltzmann machine. Although the two models we study look different from their
parametrizations, we show that they represent the same set of distributions on
the interior of the probability simplex, and are equal up to closure. We give a
semi-algebraic description of the model in terms of six binomial inequalities
and obtain closed form expressions for the maximum likelihood estimates. We
briefly discuss extensions to larger models.Comment: 18 pages, 7 figure
Metric on the space of quantum states from relative entropy. Tomographic reconstruction
In the framework of quantum information geometry, we derive, from quantum
relative Tsallis entropy, a family of quantum metrics on the space of full
rank, N level quantum states, by means of a suitably defined coordinate free
differential calculus. The cases N = 2, N = 3 are discussed in detail and
notable limits are analyzed. The radial limit procedure has been used to
recover quantum metrics for lower rank states, such as pure states. By using
the tomographic picture of quantum mechanics we have obtained the Fisher- Rao
metric for the space of quantum tomograms and derived a reconstruction formula
of the quantum metric of density states out of the tomographic one. A new
inequality obtained for probabilities of three spin-1/2 projections in three
perpendicular directions is proposed to be checked in experiments with
superconducting circuits.Comment: 31 pages. No figures. Abstract and Introduction rewritten. Minor
corrections. References adde
Quantum suprematism picture of Malevich's squares triada for spin states and the parametric oscillator evolution in the probability representation of quantum mechanics
Review of tomographic probability representation of quantum states is
presented both for oscillator systems with continious variables and
spin--systems with discrete variables. New entropic--information inequalities
are obtained for Franck--Condon factors. Density matrices of qudit states are
expressed in terms of probabilities of artificial qubits as well as the quantum
suprematism approach to geometry of these states using the triadas of Malevich
squares is developed. Examples of qubits, qutrits and ququarts are considered.Comment: the material of the talk given at Symmetries in Science Symposium,
Bregenz, 201
Supersymmetry discovery potential of the LHC at 10 and 14 TeV without and with missing
We examine the supersymmetry (SUSY) reach of the CERN LHC operating at
and 14 TeV within the framework of the minimal supergravity
model. We improve upon previous reach projections by incorporating updated
background calculations including a variety of Standard Model (SM)
processes. We show that SUSY discovery is possible even before the detectors
are understood well enough to utilize either or electrons in
the signal. We evaluate the early SUSY reach of the LHC at TeV by
examining multi-muon plus jets and also dijet events with {\it no}
missing cuts and show that the greatest reach in terms of
occurs in the dijet channel. The reach in multi-muons is slightly smaller in
, but extends to higher values of . We find that an observable
multi-muon signal will first appear in the opposite-sign dimuon channel, but as
the integrated luminosity increases the relatively background-free but
rate-limited same-sign dimuon, and ultimately the trimuon channel yield the
highest reach. We show characteristic distributions in these channels that
serve to distinguish the signal from the SM background, and also help to
corroborate its SUSY origin. We then evaluate the LHC reach in various
no-lepton and multi-lepton plus jets channels {\it including} missing
cuts for and 14 TeV, and plot the reach for integrated
luminosities ranging up to 3000 fb at the SLHC. For TeV,
the LHC reach extends to and 2.9 TeV for
and integrated luminosities of 10, 100, 1000 and
3000 fb, respectively. For TeV, the LHC reach for the same
integrated luminosities is to m_{gluino}=2.4,\3.1, 3.7 and 4.0 TeV.Comment: 34 pages, 25 figures. Revised projections for the SUSY reach for
ab^-1 integrated luminosities, with minor corrections of references and text.
2 figures added. To appear in JHE
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