9,289 research outputs found
An Adventure in Topological Phase Transitions in 3 + 1-D: Non-abelian Deconfined Quantum Criticalities and a Possible Duality
Continuous quantum phase transitions that are beyond the conventional
paradigm of fluctuations of a symmetry breaking order parameter are challenging
for theory. These phase transitions often involve emergent deconfined gauge
fields at the critical points as demonstrated in 2+1-dimensions. Examples
include phase transitions in quantum magnetism as well as those between
Symmetry Protected Topological phases. In this paper, we present several
examples of Deconfined Quantum Critical Points (DQCP) between Symmetry
Protected Topological phases in 3+1-D for both bosonic and fermionic systems.
Some of the critical theories can be formulated as non-abelian gauge theories
either in their Infra-Red free regime, or in the conformal window when they
flow to the Banks-Zaks fixed points. We explicitly demonstrate several
interesting quantum critical phenomena. We describe situations in which the
same phase transition allows for multiple universality classes controlled by
distinct fixed points. We exhibit the possibility - which we dub "unnecessary
quantum critical points" - of stable generic continuous phase transitions
within the same phase. We present examples of interaction driven band-theory-
forbidden continuous phase transitions between two distinct band insulators.
The understanding we develop leads us to suggest an interesting possible 3+1-D
field theory duality between SU(2) gauge theory coupled to one massless adjoint
Dirac fermion and the theory of a single massless Dirac fermion augmented by a
decoupled topological field theory.Comment: 83 pages, 10 figure
Review of bottomonium measurements from CMS
We review the results on the bottomonium system from the CMS experiment at
the Large Hadron Collider. Measurements have been carried out at different
center-of-mass energies in proton collisions and in collisions involving heavy
ions. These include precision measurements of cross sections and polarizations,
shedding light on hadroproduction mechanisms, and the observation of quarkonium
sequential suppression, a notable indication of quark-gluon plasma formation.
The observation of the production of bottomonium pairs is also reported along
with searches for new states. We close with a brief outlook of the future
physics program.Comment: 32 page
Testing Lorentz Invariance with Ultra High Energy Cosmic Ray Spectrum
The GZK cutoff predicted at the Ultra High Energy Cosmic Ray (UHECR) spectrum
as been observed by the HiRes and Auger experiments. The results put severe
constraints on the effect of Lorentz Invariance Violation(LIV) which has been
introduced to explain the absence of GZK cutoff indicated in the AGASA data.
Assuming homogeneous source distribution with a single power law spectrum, we
calculate the spectrum of UHECRs observed on Earth by taking the processes of
photopion production, pair production and adiabatic energy loss into
account. The effect of LIV is also taken into account in the calculation. By
fitting the HiRes monocular spectra and the Auger combined spectra, we show
that the LIV parameter is constrained to
and respectively, which is well consistent
with strict Lorentz Invariance up to the highest energy.Comment: Accepted for publication in Physical Review D 12 pages, 4 figure
Market Impact in Trader-Agents:Adding Multi-Level Order-Flow Imbalance-Sensitivity to Automated Trading Systems
Financial markets populated by human traders often exhibit "market impact",
where the traders' quote-prices move in the direction of anticipated change,
before any transaction has taken place, as an immediate reaction to the arrival
of a large (i.e., "block") buy or sell order in the market: e.g., traders in
the market know that a block buy order will push the price up, and so they
immediately adjust their quote-prices upwards. Most major financial markets now
involve many "robot traders", autonomous adaptive software agents, rather than
humans. This paper explores how to give such trader-agents a reliable
anticipatory sensitivity to block orders, such that markets populated entirely
by robot traders also show market-impact effects. In a 2019 publication Church
& Cliff presented initial results from a simple deterministic robot trader,
ISHV, which exhibits this market impact effect via monitoring a metric of
imbalance between supply and demand in the market. The novel contributions of
our paper are: (a) we critique the methods used by Church & Cliff, revealing
them to be weak, and argue that a more robust measure of imbalance is required;
(b) we argue for the use of multi-level order-flow imbalance (MLOFI: Xu et al.,
2019) as a better basis for imbalance-sensitive robot trader-agents; and (c) we
demonstrate the use of the more robust MLOFI measure in extending ISHV, and
also the well-known AA and ZIP trading-agent algorithms (which have both been
previously shown to consistently outperform human traders). We demonstrate that
the new imbalance-sensitive trader-agents introduced here do exhibit market
impact effects, and hence are better-suited to operating in markets where
impact is a factor of concern or interest, but do not suffer the weaknesses of
the methods used by Church & Cliff. The source-code for our work reported here
is freely available on GitHub.Comment: To be presented at the 13th International Conference on Agents and
Artificial Intelligence (ICAART2021), Vienna, 4th--6th February 2021. 15
pages; 9 figure
Branching ratios and CP asymmetries of decays in the pQCD approach
We calculate the branching ratios and CP violating asymmetries of the four B
\to K \etap decays in the perturbative QCD (pQCD) factorization approach.
Besides the full leading order contributions, the partial next-to-leading order
(NLO) contributions from the QCD vertex corrections, the quark loops, and the
chromo-magnetic penguins are also taken into account. The NLO pQCD predictions
for the CP-averaged branching ratios are , Br(B^\pm \to K^\pm \etar) \approx 51.0 \times 10^{-6},
, and Br(B^0 \to K^0 \etar)
\approx 50.3 \times 10^{-6}. The NLO contributions can provide a 70%
enhancement to the LO Br(B \to K \etar), but a 30% reduction to the LO , which play the key role in understanding the observed pattern of
branching ratios. The NLO pQCD predictions for the CP-violating asymmetries,
such as \acp^{dir} (K^0_S \etar) \sim 2.3% and \acp^{mix}(K^0_S \etar)\sim
63%, agree very well with currently available data. This means that the
deviation \Delta S=\acp^{mix}(K^0_S \etar) - \sin{2\beta} in pQCD approach is
also very small.Comment: 31 pages, 11 ps/eps figures, typos corrected. A little modificatio
Conodonts, Corals and Stromatoporoids from Subsurface Lower Devonian in the Northparkes Porphyry District of Central Western New South Wales and their Regional Stratigraphic Implications
Documented in this report is a small fauna recovered from an unnamed stratigraphic unit of bioclastic limestone, black shale and carbonaceous mudstone intersected in a drill hole (NPM-GD871) undertaken by CMOC-Northparkes Mines in the Northparkes porphyry district, located ca 30 km NW of Parkes, central western New South Wales. It includes six conodont species (Panderodus unicostatus, Pandorinellina exigua, Pelekysgnathus sp., Wurmiella excavata, Zieglerodina remscheidensis and gen. et sp. indet.), one rugose coral (Microplasma ronense), three tabulate coral species (Favosites duni, Squameofavosites bryani and Thamnopora minor) and one stromatoporoid species (Densastroma sp.). Faunal analysis indicates a maximum age of late Lochkovian and a minimum age of Pragian for this unit, equivalent to the upper part of the Derriwong Group. The fauna is also comparable with those recovered from the Jerula Limestone Member of the Gleninga Formation (upper part of the Yarra Yarra Creek Group) exposed farther west. Conodont data documented here suggest that the base of the Derriwong Group is diachronous across the region, and on the eastern flank of the Tullamore Syncline has a minimum age of the late Pragian rather than early Lochkovian as currently accepted
Sigma Decay at Finite Temperature and Density
Sigma decay and its relation with chiral phase transition are discussed at
finite temperature and density in the framework of the Nambu-Jona-Lasinio
model. The decay rate for the process sigma -> 2 pions to first order in a
1/N_c expansion is calculated as a function of temperature T and baryon density
n_b. In particular, only when the chiral phase transition happens around the
tricritical point, the sigma decay results in a non-thermal enhancement of
pions in the final state distributions in relativistic heavy ion collisions.Comment: 6 pages, 3 Postscript figures, submitted to Chin. Phys. Let
Composite Correlation Quantization for Efficient Multimodal Retrieval
Efficient similarity retrieval from large-scale multimodal database is
pervasive in modern search engines and social networks. To support queries
across content modalities, the system should enable cross-modal correlation and
computation-efficient indexing. While hashing methods have shown great
potential in achieving this goal, current attempts generally fail to learn
isomorphic hash codes in a seamless scheme, that is, they embed multiple
modalities in a continuous isomorphic space and separately threshold embeddings
into binary codes, which incurs substantial loss of retrieval accuracy. In this
paper, we approach seamless multimodal hashing by proposing a novel Composite
Correlation Quantization (CCQ) model. Specifically, CCQ jointly finds
correlation-maximal mappings that transform different modalities into
isomorphic latent space, and learns composite quantizers that convert the
isomorphic latent features into compact binary codes. An optimization framework
is devised to preserve both intra-modal similarity and inter-modal correlation
through minimizing both reconstruction and quantization errors, which can be
trained from both paired and partially paired data in linear time. A
comprehensive set of experiments clearly show the superior effectiveness and
efficiency of CCQ against the state of the art hashing methods for both
unimodal and cross-modal retrieval
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