780 research outputs found
On the Corner Elements of the CKM and PMNS Matrices
Recent experiments show that the top-right corner element () of the
PMNS, like that () of the CKM, matrix is small but nonzero, and suggest
further via unitarity that it is smaller than the bottom-left corner element
(), again as in the CKM case (). An attempt in
explaining these facts would seem an excellent test for any model of the mixing
phenomenon. Here, it is shown that if to the assumption of a universal rank-one
mass matrix, long favoured by phenomenologists, one adds that this matrix
rotates with scale, then it follows that (A) by inputting the mass ratios
, and , (i) the corner elements are
small but nonzero, (ii) , , (iii)
estimates result for the ratios and , and
(B) by inputting further the experimental values of and
, (iv) estimates result for the values of the corner elements
themselves. All the inequalities and estimates obtained are consistent with
present data to within expectation for the approximations made.Comment: 9 pages, 2 figures, updated with new experimental data and more
detail
N-String Vertices in String Field Theory
We give the general form of the vertex corresponding to the interaction of an
arbitrary number of strings. The technique employed relies on the ``comma"
representation of String Field Theory where string fields and interactions are
represented as matrices and operations between them such as multiplication and
trace. The general formulation presented here shows that the interaction vertex
of N strings, for any arbitrary N, is given as a function of particular
combinations of matrices corresponding to the change of representation between
the full string and the half string degrees of freedom.Comment: 22 pages, A4-Latex (latex twice), FTUV IFI
Top Quark Spin Polarization in ep Collision
We discuss the degree of spin polarization of single top quarks produced via
fusion process in collision at TESLA+HERAp and CLIC+LHC energies
and 5.3 TeV. For subprocess we show that
the top quark spin is completely polarized when the spin basis is chosen in the
direction of the incoming positron beam in the rest frame of top quark. A
description on how to combine the cross sections of and
processes is given. -beam direction is
taken to be the favorite top quark spin decomposition axis in its rest frame
and it is found to be comparable with the ones in collision. It is argued
that theoretical simplicity and experimental clearness are the advantage of
collision.Comment: Revised version of Phys. Rev. D69 (2004)03401
Mass Hierarchy, Mixing, CP-Violation and Higgs Decay---or Why Rotation is Good for Us
The idea of a rank-one rotating mass matrix (R2M2) is reviewed detailing how
it leads to ready explanations both for the fermion mass hierarchy and for the
distinctive mixing patterns between up and down fermion states, which can be
and have been tested against experiment and shown to be fully consistent with
existing data. Further, R2M2 is seen to offer, as by-products: (i) a new
solution of the strong CP problem in QCD by linking the theta-angle there to
the Kobayashi-Maskawa CP-violating phase in the CKM matrix, and (ii) some novel
predictions of possible anomalies in Higgs decay observable in principle at the
LHC. A special effort is made to answer some questions raised.Comment: 47 pages, 9 figure
Anomalous Wtb Coupling in ep Collision
The potential of ep collision to prospect for anomalous Wtb vertex is
discussed from the single top quark production process for
TESLA+HERAp and CLIC+LHC energies. Sensitivities to anomalous couplings
and , in the case of CLIC+LHC, are shown to be comparable with
LHC.Comment: 10 pages, 4 figure
Neural Networks for Information Retrieval
Machine learning plays a role in many aspects of modern IR systems, and deep
learning is applied in all of them. The fast pace of modern-day research has
given rise to many different approaches for many different IR problems. The
amount of information available can be overwhelming both for junior students
and for experienced researchers looking for new research topics and directions.
Additionally, it is interesting to see what key insights into IR problems the
new technologies are able to give us. The aim of this full-day tutorial is to
give a clear overview of current tried-and-trusted neural methods in IR and how
they benefit IR research. It covers key architectures, as well as the most
promising future directions.Comment: Overview of full-day tutorial at SIGIR 201
ASSET : a dataset for tuning and evaluation of sentence simplification models with multiple rewriting transformations
In order to simplify a sentence, human editors perform multiple rewriting transformations: they split it into several shorter sentences, paraphrase words (i.e. replacing complex words or phrases by simpler synonyms), reorder components, and/or delete information deemed unnecessary. Despite these varied range of possible text alterations, current models for automatic sentence simplification are evaluated using datasets that are focused on a single transformation, such as lexical paraphrasing or splitting. This makes it impossible to understand the ability of simplification models in more realistic settings. To alleviate this limitation, this paper introduces ASSET, a new dataset for assessing sentence simplification in English. ASSET is a crowdsourced multi-reference corpus where each simplification was produced by executing several rewriting transformations. Through quantitative and qualitative experiments, we show that simplifications in ASSET are better at capturing characteristics of simplicity when compared to other standard evaluation datasets for the task. Furthermore, we motivate the need for developing better methods for automatic evaluation using ASSET, since we show that current popular metrics may not be suitable when multiple simplification transformations are performed
A first test of the framed standard model against experiment
The framed standard model (FSM) is obtained from the standard model by incorporating, as field variables, the frame vectors (vielbeins) in internal symmetry space. It gives the standard Higgs boson and 3 generations of quarks and leptons as immediate consequences. It gives moreover a fermion mass matrix of the form: m = mT alpha alpha dagger, where alpha is a vector in generation space independent of the fermion species and rotating with changing scale, which has already been shown to lead, generically, to up-down mixing, neutrino oscillations and mass hierarchy. In this paper, pushing the FSM further, one first derives to 1-loop order the RGE for the rotation of alpha, and then applies it to fit mass and mixing data as a first test of the model. With 7 real adjustable parameters, 18 measured quantities are fitted, most (12) to within experimental error or to better than 0.5 percent, and the rest (6) not far off. (A summary of this fit can be found in Table 2 of this paper.) Two notable features, both generic to FSM, not just specific to the fit, are: (i) that a theta-angle of order unity in the instanton term in QCD would translate via rotation into a Kobayashi-Maskawa phase in the CKM matrix of about the observed magnitude (J similar to 10(-5)), (ii) that it would come out correctly that m(u) > m(b), m(c) >> m(s). Of the 18 quantities fitted, 12 are deemed independent in the usual formulation of the standard model. In fact, the fit gives a total of 17 independent parameters of the standard model, but 5 of these have not been measured by experiment
Three Numerical Puzzles and the Top Quark's Chiral Weak-Moment
Versus the standard model's t --> W b decay helicity amplitudes, three
numerical puzzles occur at the 0.1 % level when one considers the amplitudes in
the case of an additional (f_M + f_E) coupling of relative strength 53 GeV. The
puzzles are theoretical ones which involve the t --> W b decay helicity
amplitudes in the two cases, the relative strength of this additional coupling,
and the observed masses of these three particles. A deeper analytic realization
is obtained for two of them. Equivalent realizations are given for the
remaining one. An empirical consequence of these analytic realizations is that
it is important to search for effects of a large chiral weak-moment of the
top-quark, the effective mass-scale is about 53 GeV. A full theoretical
resolution would include relating the origin of such a chiral weak-moment and
the mass generation of the top-quark, the W-boson, and probably the b-quark.Comment: 18 pages, 1 postscript table (revised to better explain notation,
model #1, add a little material...
Developing the Framed Standard Model
The framed standard model (FSM) suggested earlier, which incorporates the
Higgs field and 3 fermion generations as part of the framed gauge theory
structure, is here developed further to show that it gives both quarks and
leptons hierarchical masses and mixing matrices akin to what is experimentally
observed. Among its many distinguishing features which lead to the above
results are (i) the vacuum is degenerate under a global symmetry which
plays the role of fermion generations, (ii) the fermion mass matrix is
"universal", rank-one and rotates (changes its orientation in generation space)
with changing scale , (iii) the metric in generation space is
scale-dependent too, and in general non-flat, (iv) the theta-angle term in the
QCD action of topological origin gets transformed into the CP-violating phase
of the CKM matrix for quarks, thus offering at the same time a solution to the
strong CP problem.Comment: 53 Page
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