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Author |
Carames, T.F.; Valcarce, A.; Vijande, J. |
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Title |
Too many X's, Y's and Z's? |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
709 |
Issue |
4-5 |
Pages |
358-361 |
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Keywords |
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Abstract |
A large number of new states have been reported during the last few years in charmonium spectroscopy above the charmed meson production threshold. They have been called X's, Y's, and Z's. We reflect on the influence of thresholds on heavy meson spectroscopy comparing different flavor sectors and quantum numbers. The validity of a quark-model picture above open-flavor thresholds would severely restrict the number of channels that may lodge meson-meson molecules. |
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Address |
[Carames, T. F.; Valcarce, A.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain, Email: valcarce@usal.es |
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Publisher |
Elsevier Science Bv |
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Language |
English |
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Series Volume |
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Edition |
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ISSN |
0370-2693 |
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Expedition |
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Conference |
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Notes |
WOS:000302454700005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
978 |
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Permanent link to this record |
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Author |
Casas, F.; Oteo, J.A.; Ros, J. |
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Title |
Unitary transformations depending on a small parameter |
Type |
Journal Article |
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Year |
2012 |
Publication |
Proceedings of the Royal Society A |
Abbreviated Journal |
Proc. R. Soc. A |
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Volume |
468 |
Issue |
2139 |
Pages |
685-700 |
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Keywords |
perturbation theory; quantum mechanics; unitary transformation; Magnus expansion |
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Abstract |
We formulate a unitary perturbation theory for quantum mechanics inspired by the Lie-Deprit formulation of canonical transformations. The original Hamiltonian is converted into a solvable one by a transformation obtained through a Magnus expansion. This ensures unitarity at every order in a small parameter. A comparison with the standard perturbation theory is provided. We work out the scheme up to order ten with some simple examples. |
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Address |
[Oteo, J. A.; Ros, J.] Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain, Email: rosj@uv.es |
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Publisher |
Royal Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1364-5021 |
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Conference |
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Notes |
WOS:000300185400005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
893 |
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Permanent link to this record |
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Author |
Castorina, E.; Franca, U.; Lattanzi, M.; Lesgourgues, J.; Mangano, G.; Melchiorri, A.; Pastor, S. |
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Title |
Cosmological lepton asymmetry with a nonzero mixing angle theta(13) |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
86 |
Issue |
2 |
Pages |
023517 - 11pp |
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Keywords |
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Abstract |
While the baryon asymmetry of the Universe is nowadays well measured by cosmological observations, the bounds on the lepton asymmetry in the form of neutrinos are still significantly weaker. We place limits on the relic neutrino asymmetries using some of the latest cosmological data, taking into account the effect of flavor oscillations. We present our results for two different values of the neutrino mixing angle theta(13), and show that for large theta(13) the limits on the total neutrino asymmetry become more stringent, diluting even large initial flavor asymmetries. In particular, we find that the present bounds are still dominated by the limits coming from big bang nucleosynthesis, while the limits on the total neutrino mass from cosmological data are essentially independent of theta(13). Finally, we perform a forecast for Cosmic Origins Explorer, taken as an example of a future cosmic microwave background experiment, and find that it could improve the limits on the total lepton asymmetry approximately by up to a factor 6.6. |
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Address |
[Castorina, Emanuele] SISSA, I-34136 Trieste, Italy |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000306320000003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1093 |
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Permanent link to this record |
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Author |
Catani, S.; de Florian, D.; Rodrigo, G. |
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Title |
Space-like (vs. time-like) collinear limits in QCD: is factorization violated? |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
026 - 88pp |
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Keywords |
NLO Computations; Hadronic Colliders |
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Abstract |
We consider the singular behaviour of QCD scattering amplitudes in kinematical configurations where two or more momenta of the external partons become collinear. At the tree level, this behaviour is known to be controlled by factorization formulae in which the singular collinear factor is universal (process independent). We show that this strict (process-independent) factorization is not valid at one-loop and higher-loop orders in the case of the collinear limit in space-like regions (e. g., collinear radiation from initial-state partons). We introduce a generalized version of all-order collinear factorization, in which the space-like singular factors retain some dependence on the momentum and colour charge of the non-collinear partons. We present explicit results on one-loop and two-loop amplitudes for both the two-parton and multiparton collinear limits. At the level of squared amplitudes and, more generally, cross sections in hadron-hadron collisions, the violation of strict collinear factorization has implications on the non-abelian structure of logarithmically-enhanced terms in perturbative calculations (starting from the next-to-next-to-leading order) and on various factorization issues of mass singularities (starting from the next-to-next-to-next-to-leading order). |
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Address |
[Catani, Stefano] Univ Florence, Sez Firenze, Ist Nazl Fis Nucl, I-50019 Florence, Italy, Email: catani@fi.infn.it; |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1126-6708 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000307298400026 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1160 |
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Permanent link to this record |
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Author |
CDF Collaboration (Aaltonen, T. et al); Cabrera, S. |
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Title |
Production of Lambda(0), (Lambda)over-bar(0), Xi(+/-), and Omega(+/-) hyperons in p(p)over-bar collisions at root s=1.96 TeV |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
86 |
Issue |
1 |
Pages |
012002 - 10pp |
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Keywords |
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Abstract |
We report a set of measurements of inclusive invariant p(T) differential cross sections of Lambda(0), (Lambda) over bar (0), Xi(+/-), and Omega(+/-) hyperons reconstructed in the central region with pseudorapidity vertical bar eta vertical bar < 1 and p(T) up to 10 GeV/c. Events are collected with a minimum-bias trigger in p<(p)over bar> collisions at a center-of-mass energy of 1.96 TeV using the CDF II detector at the Tevatron Collider. As p(T) increases, the slopes of the differential cross sections of the three particles are similar, which could indicate a universality of the particle production in p(T). The invariant differential cross sections are also presented for different charged-particle multiplicity intervals. |
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Address |
[Aaltonen, T.; Brucken, E.; Devoto, F.; Mehtala, P.; Orava, R.] Univ Helsinki, Dept Phys, Div High Energy Phys, FIN-00014 Helsinki, Finland |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000306412700001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1104 |
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Permanent link to this record |