| Records |
| Author |
Penalva, N.; Hernandez, E.; Nieves, J. |
| Title |
New physics and the tau polarization vector in b -> c tau barnutau decays |
Type |
Journal Article |
| Year |
2021 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
06 |
Issue |
6 |
Pages |
118 - 37pp |
| Keywords |
Beyond Standard Model; CP violation |
Abstract  |
For a general H-b -> Hc tau nu <overbar></mml:mover>tau decay we analyze the role of the tau polarization vector P μin the context of lepton flavor universality violation studies. We use a general phenomenological approach that includes, in addition to the Standard Model (SM) contribution, vector, axial, scalar, pseudoscalar and tensor new physics (NP) terms which strength is governed by, complex in general, Wilson coefficients. We show that both in the laboratory frame, where the initial hadron is at rest, and in the center of mass of the two final leptons, a P -></mml:mover> component perpendicular to the plane defined by the three-momenta of the final hadron and the tau lepton is only possible for complex Wilson coefficients, being a clear signal for physics beyond the SM as well as time reversal (or CP-symmetry) violation. We make specific evaluations of the different polarization vector components for the Lambda (b) -> Lambda (c), <mml:mover accent=“true”>B<mml:mo stretchy=“true”><overbar></mml:mover>c -> eta (c), J/psi and <mml:mover accent=“true”>B<mml:mo stretchy=“true”><overbar></mml:mover> -> D-(*) semileptonic decays, and describe NP effects in the complete two-dimensional space associated with the independent kinematic variables on which the polarization vector depends. We find that the detailed study of P μhas great potential to discriminate between different NP scenarios for 0(-) -> 0(-) decays, but also for Lambda (b) -> Lambda (c) transitions. For this latter reaction, we pay special attention to corrections to the SM predictions derived from complex Wilson coefficients contributions. |
| Address |
[Penalva, Neus; Nieves, Juan] Ctr Mixto CSIC UV, Inst Invest Paterna, Inst Fis Corpuscular, Apartado 22085, Valencia 46071, Spain, Email: Neus.Penalva@ific.uv.es; |
| Corporate Author |
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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 |
1029-8479 |
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:000664505100002 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
no |
| Call Number |
IFIC @ pastor @ |
Serial |
4882 |
| Permanent link to this record |
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| Author |
Penalva, N.; Hernandez, E.; Nieves, J. |
| Title |
Further tests of lepton flavor universality from the charged lepton energy distribution in b -> c semileptonic decays: The case of Lambda(b) -> Lambda(c) l(v)over-bar(l) |
Type |
Journal Article |
| Year |
2019 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
100 |
Issue |
11 |
Pages |
113007 - 11pp |
| Keywords |
|
| Abstract |
In a general framework, valid for any H -> H' l(-)(v) over bar (l) semileptonic decay, we analyze the d(2)Gamma/(d omega d cos theta(l)) and d(2)Gamma/(d omega dE(l)) distributions, with omega being the product of the hadron four-velocities, theta(l) the angle made by the three-momenta of the charged lepton and the final hadron in the W- center of mass frame and E-l the charged lepton energy in the decaying hadron rest frame. Within the Standard Model (SM), d(2)Gamma/(d omega dE(l)) proportional to (c(0) (omega) c(1) (omega)E-l/M + c(2) (omega)E-l(2)/M-2), with M the initial hadron mass. We find that c(2) (omega) is independent of the lepton flavor and thus it is an ideal candidate to look for lepton flavor universality (LFU) violations. We also find a correlation between the a(2) (omega) structure function, which governs the (cos theta(l))(2) dependence of d(2)Gamma/(d omega d cos theta(l)), and c(2) (omega). Apart from trivial kinematical and mass factors, the ratio of a(2) (omega)/c(2) (omega) is a universal function that can be measured in any semileptonic decay, involving not only b -> c transitions. These two SM predictions can be used as new tests in the present search for signatures of LFU violations. We also generalize the formalism to account for some new physics (NP) terms, and show that neither c(2) nor a(2) are modified by left and right scalar NP terms, being however sensitive to left and right vector corrections. We also find that the a(2)/c(2) ratio is not modified by these latter NP contributions. Finally, and in order to illustrate our findings, we apply our general framework to the Lambda(b) -> Lambda(c)l (v) over bar (l) decay. We show that a measurement of c(2) (or a(2)) for tau decay would not only be a direct measurement of the possible existence of NP, but it would also allow to distinguish from NP fits to b -> c tau(v) over bar (tau) anomalies in the meson sector, which otherwise give the same total and differential d Gamma/d omega widths. We show that the same occurs for the other two terms, c(0) and c(1), that appear in d(2)Gamma/(d omega dE(l)), and for the cos theta(l) linear term of the angular distribution. |
| Address |
[Penalva, Neus; Nieves, Juan] Ctr Mixto CSIC UV, Inst Invest Paterna, Inst Fis Corpuscular, Apartado 22085, Valencia 46071, Spain |
| 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 |
2470-0010 |
ISBN |
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Medium |
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| Area |
|
Expedition |
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Conference |
|
| Notes |
WOS:000503400600001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
no |
| Call Number |
IFIC @ pastor @ |
Serial |
4230 |
| Permanent link to this record |
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| Author |
Penalva, N.; Hernandez, E.; Nieves, J. |
| Title |
The role of right-handed neutrinos in b -> c tau (pi nu(tau), rho nu(tau), mu(nu)over-bar(mu)nu(tau))(nu)over-bar(tau) from visible final-state kinematics |
Type |
Journal Article |
| Year |
2021 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
10 |
Issue |
10 |
Pages |
122 - 45pp |
| Keywords |
Beyond Standard Model; CP violation |
| Abstract |
In the context of lepton flavor universality violation (LFUV) studies, we fully derive a general tensor formalism to investigate the role that left- and right-handed neutrino new-physics (NP) terms may have in b -> c tau(nu) over bar (tau) transitions. We present, for several extensions of the Standard Model (SM), numerical results for the Lambda(b) -> Lambda(c)tau(nu) over bar (tau) semileptonic decay, which is expected to be measured with precision at the LHCb. This reaction can be a new source of experimental information that can help to confirm, or maybe rule out, LFUV presently seen in (B) over bar meson decays. The present study analyzes observables that can help in distinguishing between different NP scenarios that otherwise provide very similar results for the branching ratios, which are our currently best hints for LFUV. Since the tau lepton is very short-lived, we consider three subsequent tau-decay modes, two hadronic pi nu(tau) and rho nu(tau) and one leptonic mu(nu) over bar (mu)nu(tau), which have been previously studied for (B) over bar -> D(*) decays. Within the tensor formalism that we have developed in previous works, we re-obtain the expressions for the differential decay width written in terms of visible (experimentally accessible) variables of the massive particle created in the tau decay. There are seven different tau angular and spin asymmetries that are defined in this way and that can be extracted from experiment. Those asymmetries provide observables that can help in constraining possible SM extensions. |
| Address |
[Penalva, Neus; Nieves, Juan] Ctr Mixto CSIC UV, Inst Fis Corpuscular, Inst Invest Paterna, C Catedrat Jose Beltran 2, E-46980 Valencia, Spain, Email: neus.penalva@ific.uv.es; |
| Corporate Author |
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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 |
1029-8479 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
|
| Notes |
WOS:000708483600004 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
no |
| Call Number |
IFIC @ pastor @ |
Serial |
5005 |
| Permanent link to this record |
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| Author |
Penalva, N.; Hernandez, E.; Nieves, J. |
| Title |
(B)over-bar(c) ->eta(c),(B)over-bar(c) -> J/psi and (B)over-bar -> D-(*()) semileptonic decays including new physics |
Type |
Journal Article |
| Year |
2020 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
102 |
Issue |
9 |
Pages |
096016 - 27pp |
| Keywords |
|
| Abstract |
We apply the general formalism derived by Penalva et al. [Phys. Rev. D 101, 113004 (2020)] to the semileptonic decay of pseudoscalar mesons containing a b quark. While present (B) over bar -> D-(*()) data give the strongest evidence in favor of lepton flavor universality violation, the observables that are normally considered are not able to distinguish between different new physics (NP) scenarios. In the above reference we discussed the relevant role that the various contributions to the double differential decay widths d(2)Gamma (d omega d cos theta(l)) and d(2)Gamma (d omega dE(l)) could play to this end. Here omega is the product of the two hadron fourvelocities, theta(l) is the angle made by the final lepton and final hadron three-momenta in the center of mass of the final two-lepton system, and E-l is the final charged lepton energy in the laboratory system. The formalism was applied by Penalva et al. to the analysis of the Lambda(b) -> Lambda(c) semileptonic decay, showing the new observables were able to tell apart different NP scenarios. Here we analyze the (B) over barc -> eta(c)tau(nu) over bar (tau), (B) over barc -> J/psi tau(nu) over bar (tau), (B) over bar -> D tau(nu) over bar (tau) and (B) over bar -> D*tau(nu) over bar (tau) , semileptonic decays. We find that, as a general rule, the (B) over barc -> J/psi observables, even including (tau) polarization, are less optimal for distinguishing between NP scenarios than those obtained from (B) over barc -> eta(c) decays, or those presented by Penalva et al. for the related Lambda(b) -> Lambda(c) semileptonic decay. Finally, we show that (B) over bar -> D and (B) over barc -> eta(c) , and (B) over bar -> D* and (B) over barc -> J/psi decay observables exhibit similar behaviors. |
| Address |
[Penalva, Neus; Hernandez, Eliecer] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain |
| 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 |
2470-0010 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
|
| Notes |
WOS:000588583900012 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
no |
| Call Number |
IFIC @ pastor @ |
Serial |
4608 |
| Permanent link to this record |
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| Author |
Du, M.L.; Penalva, N.; Hernandez, E.; Nieves, J. |
| Title |
New physics effects on Lambda(b) -> Lambda(c)*tau(nu)over-bar(tau) decays |
Type |
Journal Article |
| Year |
2022 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
106 |
Issue |
5 |
Pages |
055039 - 21pp |
| Keywords |
|
| Abstract |
We benefit from a recent lattice determination of the full set of vector, axial and tensor form factors for the Lambda(b) -> Lambda(c)* (2595)tau(nu) over bar (tau) and Lambda(c) (2625)tau(nu) over bar (tau) semileptonic decays to study the possible role of these two reactions in lepton flavor universality violation studies. Using an effective theory approach, we analyze different observables that can be accessed through the visible kinematics of the charged particles produced in the tau decay, for which we consider the pi(-)nu(tau), rho(-) nu(tau) and mu(-)(nu) over bar (mu)nu(tau) channels. We compare the results obtained in the Standard Model and other schemes containing new physics (NP) interactions, with either left-handed or right-handed neutrino operators. We find a discriminating power between models similar to the one of the Lambda(b) -> Lambda(c) decay, although somewhat hindered in this case by the larger errors of the Lambda(b) -> Lambda(c)* lattice form factors. Notwithstanding this, the analysis of these reactions is already able to discriminate between some of the NP scenarios and its potentiality will certainly improve when more precise form factors are available. |
| Address |
[Du, Meng-Lin; Penalva, Neus; Nieves, Juan] Inst Fis Corpuscular Ctr Mixto CSIC UV, Inst Invest Paterna, C Catedrat Jose Beltran 2, E-46980 Valencia, Spain |
| 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 |
2470-0010 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
|
| Notes |
WOS:000870152800009 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
no |
| Call Number |
IFIC @ pastor @ |
Serial |
5401 |
| Permanent link to this record |
