LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2016). Differential branching fraction and angular moments analysis of the decay B-0 -> K+pi(-)mu(+)mu(-) in the K-0,K-2*(1431:)(0) region. J. High Energy Phys., 12(12), 065–24pp.
Abstract: Measurements of the differential branching fraction and angular moments of the decay B-0 -> K+pi(-)mu(+)mu(-) in the K+pi(-) invariant mass range 1330 <m(K+pi(-)) < 1530 MeV/c(2) are presented. Proton-proton collision data are used, corresponding to an integrated luminosity of 3 fb(-1) collected by the LHCb experiment. Differential branching fraction measurements are reported in five bins of the invariant mass squared of the dimuon system, q(2), between 0.1 and 8.0 GeV2/c(4). For the first time, an angular analysis sensitive to the S-, P- and D-wave contributions of this rare decay is performed. The set of 40 normalised angular moments describing the decay is presented for the q(2) range 1.1-6.0 GeV2/c(4).
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Model-independent measurement of mixing parameters in D-0 -> K-S(0)pi(+)pi(-) decays. J. High Energy Phys., 04(4), 033–26pp.
Abstract: The first model-independent measurement of the charm mixing parameters in the decay D-0 -> K-S(0)pi(+)pi(-) is reported, using a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 1.0 fb(-1) at a centre-of-mass energy of 7 TeV. The measured values are x = (0.86 +/- 0.53 +/- 0.17) x 10(-2), y = (+0.03 +/- 0.46 +/- 0.13) x 10(-2), where the first uncertainties are statistical and include small contributions due to the external input for the strong phase measured by the CLEO collaboration, and the second uncertainties are systematic.
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Double Chooz collaboration(Abe, Y. et al), & Novella, P. (2016). Measurement of theta(13) in Double Chooz using neutron captures on hydrogen with novel background rejection techniques. J. High Energy Phys., 01(1), 163–29pp.
Abstract: The Double Chooz collaboration presents a measurement of the neutrino mixing angle theta(13) using reactor (nu) over bar (e) observed via the inverse beta decay reaction in which the neutron is captured on hydrogen. This measurement is based on 462.72 live days data, approximately twice as much data as in the previous such analysis, collected with a detector positioned at an average distance of 1050m from two reactor cores. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties. Accidental coincidences, the dominant background in this analysis, are suppressed by more than an order of magnitude with respect to our previous publication by a multi-variate analysis. These improvements demonstrate the capability of precise measurement of reactor (nu) over bar (e) without gadolinium loading. Spectral distortions from the (nu) over bar (e) reactor flux predictions previously reported with the neutron capture on gadolinium events are confirmed in the independent data sample presented here. A value of sin(2) 2 theta(13) = 0.095(0.039)(+0.039)(stat+syst) is obtained from a fit to the observed event rate as a function of the reactor power, a method insensitive to the energy spectrum shape. A simultaneous fit of the hydrogen capture events and of the gadolinium capture events yields a measurement of sin(2) 2 theta(13) = 0.088 +/- 0.033(stat+syst).
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NA62 Collaboration(Cortina Gil, E. et al), & Husek, T. (2020). An investigation of the very rare K+ -> pi+ nu nubar decay. J. High Energy Phys., 11(11), 042–57pp.
Abstract: The NA62 experiment reports an investigation of the K+-> pi+nu nu <overbar></mml:mover> mode from a sample of K+ decays collected in 2017 at the CERN SPS. The experiment has achieved a single event sensitivity of (0.389 +/- 0.024) x 10(-10), corresponding to 2.2 events assuming the Standard Model branching ratio of (8.4 +/- 1.0) x 10(-11). Two signal candidates are observed with an expected background of 1.5 events. Combined with the result of a similar analysis conducted by NA62 on a smaller data set recorded in 2016, the collaboration now reports an upper limit of 1.78 x 10(-10) for the K+-> pi+nu nu <overbar></mml:mover> branching ratio at 90% CL. This, together with the corresponding 68% CL measurement of (0.48<mml:mo>-0.48<mml:mo>+0.72) x 10(-10), are currently the most precise results worldwide, and are able to constrain some New Physics models that predict large enhancements still allowed by previous measurements.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fernandez Martinez, P., et al. (2016). Measurement of the CP-violating phase phi(s) and the B-s(0) meson decay width difference with B-s(0) -> J/psi phi decays in ATLAS. J. High Energy Phys., 08(8), 147–45pp.
Abstract: A measurement of the B-s(0) decay parameters in the B-s(0) -> J/psi/phi channel using an integrated luminosity of 14.3 fb(-1) collected by the ATLAS detector from 8TeV pp collisions at the LHC is presented. The measured parameters include the CP-violating phase phi(s), the decay width Gamma(s) and the width di ff erence between the mass eigenstates Delta Gamma(s). The values measured for the physical parameters are statistically combined with those from 4.9 fb-1 of 7TeV data, leading to the following: phi(s) = -0.090 +/- 0.078 (stat.) +/- 0.041 (syst.) rad Delta Gamma s = 0.085 +/- 0.011 (stat.) +/- 0.007 (syst.) ps(-1) Gamma(s) = 0.675 +/- 0.003 (stat.) +/- 0.003 (syst:) ps(-1). In the analysis the parameter Delta Gamma(s) is constrained to be positive. Results for phi(s) and Delta Gamma(s) are also presented as 68% and 95% likelihood contours in the phi(s)-Delta Gamma(s) plane. Also measured in this decay channel are the transversity amplitudes and corresponding strong phases. All measurements are in agreement with the Standard Model predictions.
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Calibbi, L., Perez, J. J., Masiero, A., Park, J. H., Porod, W., & Vives, O. (2010). FCNC and CP violation observables in an SU(3)-flavoured MSSM. Nucl. Phys. B, 831(1-2), 26–71.
Abstract: A non-Abelian flavour symmetry in a minimal supersymmetric standard model can explain the flavour structures in the Yukawa couplings and simultaneously solve the SUSY flavour problem. Similarly the SUSY CP problem can be solved if CP is spontaneously broken in the flavour sector. In this work, we present an explicit example of these statements with an SU(3) flavour symmetry and spontaneous CP violation. In addition, we show that it is still possible to find some significant deviation from the SM expectations as far as FCNC and CP violation are concerned. We find that large contributions can be expected in lepton flavour violating decays, as μ-> e gamma and tau -> μgamma, electric dipole moments, d(e) and d(n) and kaon CP violating processes as epsilon(K). We also show that without further modifications, it is unlikely for these models to solve the Phi(Bs) anomaly at low-moderate tan beta. Thus, these flavoured MSSM realizations are phenomenologically sensitive to the experimental searches in the realm of flavor and CP violation physics.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2021). Search for the doubly charmed baryon Xi(+)(cc) in the Xi(+)(c)pi(-)pi(+) final state. J. High Energy Phys., 12(12), 107–27pp.
Abstract: A search for the doubly charmed baryon Xi(+)(cc) is performed in the Xi(+)(c)pi(-)pi(+ )invariant-mass spectrum, where the Xi(-)(cc) baryon is reconstructed in the pK(-)pi(+) final state. The study uses proton-proton collision data collected with the LHCb detector at a centreof-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fb(-1). No significant signal is observed in the invariant-mass range of 3.4-3.8 GeV/c(2). Upper limits are set on the ratio of branching fractions multiplied by the production cross-section with respect to the Xi(++)(cc) -> (Xi(+)(c) -> pK(-)pi(+)+/-)pi(+ ) decay for different Xi(+)(cc) mass and lifetime hy- potheses in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2.5 to 25 GeV/c. The results from this search are combined with a previously published search for the Xi(+)(cc) -> A(c)(+)K(-)pi(+ ) decay mode, yielding a maximum local significance of 4.0 standard deviations around the mass of 3620 MeV/c(2), including systematic uncertainties. Taking into account the look-elsewhere effect in the 3.5-3.7 GeV/c(2) mass window, the combined global significance is 2.9 standard deviations including systematic uncertainties.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of branching fraction ratios for B+ -> D*+D-K+, B+ -> D*-D+K+, and B-0 -> (D*-DK+)-K-0 decays. J. High Energy Phys., 12(12), 139–22pp.
Abstract: A measurement of four branching-fraction ratios for three-body decays of B mesons involving two open-charm hadrons in the final state is presented. Run 1 and Run 2 pp collision data are used, recorded by the LHCb experiment at centre-of-mass energies 7, 8, and 13 TeV and corresponding to an integrated luminosity of 9 fb(-1). The measured branching-fraction ratios are<disp-formula id=“Equa”><mml:mtable displaystyle=“true”><mml:mtr><mml:mtd><mml:mfrac>B<mml:mfenced close=“)” open=“(”>B+-> D+D-K+</mml:mfenced>B<mml:mfenced close=“)” open=“(”>B+-> D<overbar></mml:mover>0D0K+</mml:mfenced></mml:mfrac>=0.5170.0150.013 +/- 0.011,</mml:mtd></mml:mtr><mml:mtr><mml:mtd><mml:mfrac>B<mml:mfenced close=“)” open=“(”>B+-> D-D+K+</mml:mfenced>B<mml:mfenced close=“)” open=“(”>B+-> D<overbar></mml:mover>0D0K+</mml:mfenced></mml:mfrac>=0.577 +/- 0.016 +/- 0.013 +/- 0.013,</mml:mtd></mml:mtr><mml:mtr><mml:mtd><mml:mtable><mml:mtr><mml:mtd><mml:mfrac>B<mml:mfenced close=“)” open=“(”>B0 -> D-D0K+</mml:mfenced>B<mml:mfenced close=“)” open=“(”>B0 -> D-D0K+</mml:mfenced></mml:mfrac>=1.754 +/- 0.028 +/- 0.016 +/- 0.035,</mml:mtd></mml:mtr><mml:mtr><mml:mtd><mml:mfrac>B<mml:mfenced close=“)” open=“(”>B+-> D+D-K+</mml:mfenced>B<mml:mfenced close=“)” open=“(”>B+-> D-D+K+</mml:mfenced></mml:mfrac>=0.907 +/- 0.033<mml:mo>+/- 0.014<mml:mo>,</mml:mtd></mml:mtr></mml:mtable></mml:mtd></mml:mtr></mml:mtable><graphic position=“anchor” xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:href=“13130 202014428 ArticleEqua.gif”></graphic></disp-formula><p id=“Par2”>where the first of the uncertainties is statistical, the second systematic, and the third is due to the uncertainties on the D-meson branching fractions. These are the most accurate measurements of these ratios to date.<fig id=“Figa” position=“anchor”><graphic position=“anchor” specific-use=“HTML” mime-subtype=“JPEG” xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:href=“MediaObjects/13130 202014428 FigaHTML.jpg” id=“MO1”></graphic
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Study of B-c(+) decays to charmonia and three light hadrons. J. High Energy Phys., 01(1), 065–28pp.
Abstract: Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb(-1) collected with the LHCb detector, seven decay modes of the B-C(+) meson into a J/psi or psi(2S) meson and three charged hadrons, kaons or pions, are studied. The decays B-C (+)-> (psi(2S) -> J/psi pi(+)pi(-))pi(+), B+C -> (psi(2S)pi(+)pi(-)pi(+), B+C -> J/psi K+pi(-)pi(+) and B+C -> J/K+K-K+ are observed for the first time, and evidence for the B-C (+)-> (psi(2S)K+K-pi(+), decay is found, where J/psi and psi(2S) mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different B-C(+) decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Search for the radiative Xi(-)(b) -> Xi(-)gamma decay. J. High Energy Phys., 01(1), 069–20pp.
Abstract: The first search for the rare radiative decay Xi(-)(b) -> Xi(-)gamma is performed using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.4 fb(-1). The Xi(-)(b) -> Xi(-)-J/ psi channel is used as normalization. No Xi(-)(b) -> Xi(-)gamma signal is found and an upper limit of B(Xi(-)(b) -> Xi(-)gamma) < 1.3 x 10(-4) at 95% confidence level is obtained.
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