| Records |
| Author |
LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Henry, L.; Jashal, B.K.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Vidal, J.; Sanchez Mayordomo, C. |
| Title |
Measurement of Charged Hadron Production in Z-Tagged Jets in Proton-Proton Collisions at root s=8 TeV |
Type |
Journal Article |
| Year |
2019 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
| Volume |
123 |
Issue |
23 |
Pages |
232001 - 11pp |
| Keywords |
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| Abstract |
The production of charged hadrons within jets recoiling against a Z boson is measured in proton-proton collision data at root s = 8 TeV recorded by the LHCb experiment. The charged-hadron structure of the jet is studied longitudinally and transverse to the jet axis for jets with transverse momentum p(T) > 20 GeV and in the pseudorapidity range 2.5 < eta< 4. These are the first measurements of jet hadronization at these forward rapidities and also the first where the jet is produced in association with a Z boson. In contrast to previous hadronization measurements at the Large Hadron Collider, which are dominated by gluon jets, these measurements probe predominantly light-quark jets which are found to be more longitudinally and transversely collimated with respect to the jet axis when compared to the previous gluon dominated measurements. Therefore, these results provide valuable information on differences between quarks and gluons regarding nonperturbative hadronization dynamics. |
| Address |
[Bediaga, I; Cruz Torres, M.; De Miranda, J. M.; dos Reis, A. C.; Gomes, A.; Massafferri, A.; Soares Lavra, I; Tourinho Jadallah Aoude, R.] Ctr Brasileiro Pesquisas Fis, Rio De Janeiro, Brazil |
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Thesis |
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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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0031-9007 |
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Conference |
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| Notes |
WOS:000500743400007 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
4217 |
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| Author |
LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Henry, L.; Jashal, B.K.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Vidal, J.; Sanchez Mayordomo, C. |
| Title |
Amplitude Analysis of B-+/- -> pi(K+K-)-K-+/- Decays |
Type |
Journal Article |
| Year |
2019 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
| Volume |
123 |
Issue |
23 |
Pages |
231802 - 11pp |
| Keywords |
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| Abstract |
The first amplitude analysis of the B-+/- -> pi(K+K-)-K-+/- decay is reported based on a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions recorded in 2011 and 2012 with the LHCb detector. The data are found to be best described by a coherent sum of five resonant structures plus a nonresonant component and a contribution from pi pi <-> KK S-wave rescattering. The dominant contributions in the pi(+/-) K(-/+ )and K+ K- systems are the nonresonant and the B-+/- -> rho(1450)(0)pi(+/-) amplitudes, respectively, with fit fractions around 30%. For the rescattering contribution, a sizable fit fraction is observed. This component has the largest CP asymmetry reported to date for a single amplitude of (-66 +/- 4 +/- 2)%, where the first uncertainty is statistical and the second systematic. No significant CP violation is observed in the other contributions. |
| Address |
[Bediaga, I.; Cruz Torres, M.; De Miranda, J. M.; Gomes, A.; Massafferri, A.; dos Reis, A. C.; Soares Lavra, L.; Tourinho Jadallah Aoude, R.] CBPF, Rio De Janeiro, Brazil, Email: maria.vieites.diaz@cern.ch |
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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 Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0031-9007 |
ISBN |
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Medium |
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Expedition |
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Conference |
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| Notes |
WOS:000501494600002 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
4218 |
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| Author |
LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Henry, L.; Jashal, B.K.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Vidal, J.; Sanchez Mayordomo, C. |
| Title |
Search for Lepton-Flavor Violating Decays B+ -> K+ mu(+/-) e(-/+) |
Type |
Journal Article |
| Year |
2019 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
| Volume |
123 |
Issue |
24 |
Pages |
241802 - 11pp |
| Keywords |
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| Abstract |
A search for the lepton-flavor violating decays B+ -> K+ mu(+/-)e(-/+) is performed using a sample of proton-proton collision data, collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponding to an integrated luminosity of 3 fb(-1). No significant signal is observed, and upper limits on the branching fractions are set as B(B+ -> K+ mu(+/-)e(+)) < 7.0(95) x 10(-9) and B(B+ -> K+ mu(+/- )e(-)) < 6.4(8.8) x 10(-9) at 90% (95)% confidence level. The results improve the current best limits on these decays by more than one order of magnitude. |
| Address |
[Bediaga, I.; Cruz Torres, M.; De Miranda, J. M.; Gomes, A.; Massafferri, A.; dos Reis, A. C.; Soares Lavra, L.; Tourinho Jadallah Aoude, R.] CBPF, Rio De Janeiro, Brazil, Email: maria.vieites.diaz@cern.ch |
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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 Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0031-9007 |
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:000502271300004 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
4235 |
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| Author |
Etxebeste, A.; Barrio, J.; Bernabeu, J.; Lacasta, C.; Llosa, G.; Muñoz, E.; Ros, A.; Oliver, J.F. |
| Title |
Study of sensitivity and resolution for full ring PET prototypes based on continuous crystals and analytical modeling of the light distribution |
Type |
Journal Article |
| Year |
2019 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
| Volume |
64 |
Issue |
3 |
Pages |
035015 - 17pp |
| Keywords |
continuous crystals; NEMA NU 4-2008; positron emission tomography (PET); Monte Carlo simulations; image reconstruction; depth of interaction |
| Abstract |
Sensitivity and spatial resolution are the main parameters to maximize in the performance of a PET scanner. For this purpose, detectors consisting of a combination of continuous crystals optically coupled to segmented photodetectors have been employed. With the use of continuous crystals the sensitivity is increased with respect to the pixelated crystals. In addition, spatial resolution is no longer limited to the crystal size. The main drawback is the difficulty in determining the interaction position. In this work, we present the characterization of the performance of a full ring based on cuboid continuous crystals coupled to SiPMs. To this end, we have employed the simulations developed in a previous work for our experimental detector head. Sensitivity could be further enhanced by using tapered crystals. This enhancement is obtained by increasing the solid angle coverage, reducing the wedge-shaped gaps between contiguous detectors. The performance of the scanners based on both crystal geometries was characterized following NEMA NU 4-2008 standardized protocol in order to compare them. An average sensitivity gain over the entire axial field of view of 13.63% has been obtained with tapered geometry while similar performance of the spatial resolution has been proven with both scanners. The activity at which NECR and true peak occur is smaller and the peak value is greater for tapered crystals than for cuboid crystals. Moreover, a higher degree of homogeneity was obtained in the sensitivity map due to the tighter packing of the crystals, which reduces the gaps and results in a better recovery of homogeneous regions than for the cuboid configuration. Some of the results obtained, such as spatial resolution, depend on the interaction position estimation and may vary if other method is employed. |
| Address |
[Etxebeste, Ane; Barrio, John; Bernabeu, Jose; Lacasta, Carlos; Llosa, Gabriela; Munoz, Enrique; Ros, Ana; Oliver, Josef F.] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia, Spain, Email: ane.etxebeste@ific.uv.es |
| Corporate Author |
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Thesis |
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| Publisher |
Iop Publishing Ltd |
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 Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0031-9155 |
ISBN |
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Medium |
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Expedition |
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Conference |
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| Notes |
WOS:000457182500004 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
3897 |
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| Author |
Curtin, D. et al; Hirsch, M. |
| Title |
Long-lived particles at the energy frontier: the MATHUSLA physics case |
Type |
Journal Article |
| Year |
2019 |
Publication |
Reports on Progress in Physics |
Abbreviated Journal |
Rep. Prog. Phys. |
| Volume |
82 |
Issue |
11 |
Pages |
116201 - 133pp |
| Keywords |
Large Hadron Collider; long-lived particles; hierarchy problem; dark matter; baryogenesis; neutrinos; simplified models |
| Abstract |
We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a comprehensive survey of standard model (SM) extensions. LLPs are a common prediction of a wide range of theories that address unsolved fundamental mysteries such as naturalness, dark matter, baryogenesis and neutrino masses, and represent a natural and generic possibility for physics beyond the SM (BSM). In most cases the LLP lifetime can be treated as a free parameter from the μm scale up to the Big Bang Nucleosynthesis limit of similar to 10(7) m. Neutral LLPs with lifetimes above similar to 100 m are particularly difficult to probe, as the sensitivity of the LHC main detectors is limited by challenging backgrounds, triggers, and small acceptances. MATHUSLA is a proposal for a minimally instrumented, large-volume surface detector near ATLAS or CMS. It would search for neutral LLPs produced in HL-LHC collisions by reconstructing displaced vertices (DVs) in a low-background environment, extending the sensitivity of the main detectors by orders of magnitude in the long-lifetime regime. We study the LLP physics opportunities afforded by a MATHUSLA-like detector at the HL-LHC, assuming backgrounds can be rejected as expected. We develop a model-independent approach to describe the sensitivity of MATHUSLA to BSM LLP signals, and compare it to DV and missing energy searches at ATLAS or CMS. We then explore the BSM motivations for LLPs in considerable detail, presenting a large number of new sensitivity studies. While our discussion is especially oriented towards the long-lifetime regime at MATHUSLA, this survey underlines the importance of a varied LLP search program at the LHC in general. By synthesizing these results into a general discussion of the top-down and bottom-up motivations for LLP searches, it is our aim to demonstrate the exceptional strength and breadth of the physics case for the construction of the MATHUSLA detector. |
| Address |
[Curtin, David] Univ Toronto, Dept Phys, Toronto, ON M5S 1A7, Canada, Email: dcurtin@physics.utoronto.ca |
| Corporate Author |
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Thesis |
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| Publisher |
Iop Publishing Ltd |
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 Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0034-4885 |
ISBN |
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Medium |
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Expedition |
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Conference |
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| Notes |
WOS:000499698000001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
4215 |
| Permanent link to this record |
