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Fonseca, R. M., & Hirsch, M. (2018). Delta L >= 4 lepton number violating processes. Phys. Rev. D, 98(1), 015035–12pp.
Abstract: We discuss the experimental prospects for observing processes which violate lepton number (Delta L) in four units ( or more). First, we reconsider neutrinoless quadruple beta decay, deriving a model independent and very conservative lower limit on its half- life of the order of 10(41) ys for Nd-150. This renders quadruple beta decay unobservable for any feasible experiment. We then turn to a more general discussion of different possible low-energy processes with values Delta L >= 4. A simple operator analysis leads to rather pessimistic conclusions about the observability at low-energy experiments in all cases we study. However, the situation looks much brighter for accelerator experiments. For two example models with Delta L = 4 and another one with Delta L = 5, we show how the LHC or a hypothetical future pp collider, such as the FCC, could probe multilepton number violating operators at the TeV scale.
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Fonseca, R. M., Hirsch, M., & Srivastava, R. (2018). Delta L=3 processes: Proton decay and the LHC. Phys. Rev. D, 97(7), 075026–7pp.
Abstract: We discuss lepton number violation in three units. From an effective field theory point of view, Delta L = 3 processes can only arise from dimension 9 or higher operators. These operators also violate baryon number, hence many of them will induce proton decay. Given the high dimensionality of these operators, in order to have a proton half-life in the observable range, the new physics associated to Delta L = 3 processes should be at a scale as low as 1 TeV. This opens up the possibility of searching for such processes not only in proton decay experiments but also at the LHC. In this work we analyze the relevant d = 9, 11, 13 operators which violate lepton number in three units. We then construct one simple concrete model with interesting low- and high-energy phenomenology.
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Hiller Blin, A. N., Ledwig, T., & Vicente Vacas, M. J. (2016). Delta(1232) resonance in the (gamma)over-right-arrowp -> p pi(0) reaction at threshold. Phys. Rev. D, 93(9), 094018–19pp.
Abstract: We calculate the neutral pion photoproduction on the proton near threshold in covariant baryon chiral perturbation theory, including the Delta(1232) resonance as an explicit degree of freedom, up to chiral order p(7/2) in the delta counting. We compare our results with recent low-energy data from the Mainz Microtron for angular distributions and photon asymmetries. The convergence of the chiral series of the covariant approach is found to improve substantially with the inclusion of the Delta(1232) resonance.
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Nieves, J., & Valderrama, M. P. (2011). Deriving the existence of B(B)over-bar* bound states from the X(3872) and heavy quark symmetry. Phys. Rev. D, 84(5), 056015–21pp.
Abstract: We discuss the possibility and the description of bound states between B and (B) over bar* mesons. We argue that the existence of such a bound state can be deduced from (i) the weakly bound X(3872) state, (ii) certain assumptions about the short-range dynamics of the D (D) over bar* system and (iii) heavy quark symmetry. From these assumptions the binding energy of the possible B (B) over bar* bound states is determined, first in a theory containing only contact interactions which serves as a straightforward illustration of the method, and then the effects of including the one-pion exchange potential are discussed. In this latter case three isoscalar states are predicted: a positive and negative C-parity (3)S(1) – (3)D(1) state with a binding energy of 20 MeV and 6 MeV below threshold, respectively, and a positive C-parity (3)P(0) shallow state located almost at the B (B) over bar* threshold. However, large uncertainties are generated as a consequence of the 1/m(Q) corrections from heavy quark symmetry. Finally, the newly discovered isovector Z(b)(10610) state can be easily accommodated within the present framework by a minor modification of the short-range dynamics.
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Roca, L., & Oset, E. (2010). Description of the f(2)(1270), rho(3)(1690), f(4)(2050), rho(5)(2350), f(6)(2510) resonances as multi-rho(770) states. Phys. Rev. D, 82(5), 054013–11pp.
Abstract: In a previous work regarding the interaction of two rho(770) resonances, the f(2)(1270) (J(PC) = 2(++)) resonance was obtained dynamically as a two-rho molecule with a very strong binding energy, 135 MeV per rho particle. In the present work we use the rho rho interaction in spin 2 and isospin 0 channel to show that the resonances rho(3)(1690) (3(--)), f(4)(2050) (4(++)), rho(5)(2350) (5(--)), and f(6)(2510) (6(++)) are basically molecules of increasing number of rho(770) particles. We use the fixed center approximation of the Faddeev equations to write the multibody interaction in terms of the two-body scattering amplitudes. We find the masses of the states very close to the experimental values and we get an increasing value of the binding energy per rho as the number of rho mesons is increased.
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Afonso, V. I., Bejarano, C., Ferraro, R., & Olmo, G. J. (2022). Determinantal Born-Infeld coupling of gravity and electromagnetism. Phys. Rev. D, 105(8), 084067–11pp.
Abstract: We study a Born-Infeld inspired model of gravity and electromagnetism in which both types of fields are treated on an equal footing via a determinantal approach in a metric-aft me formulation. Though this formulation is a priori in conflict with the postulates of metric theories of gravity, we find that the resulting equations can also be obtained from an action combining the Einstein-Hilbert action with a minimally coupled nonlinear electrodynamics. As an example, the dynamics is solved for the charged static black hole.
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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). Determination of quantum numbers for several excited charmed mesons observed in B- -> D*(+)pi(-) pi(-) decays. Phys. Rev. D, 101(3), 032005–24pp.
Abstract: A four-body amplitude analysis of the B- -> D*(+)pi(-) pi(-) decay is performed, where fractions and relative phases of the various resonances contributing to the decay are measured. Several quasi-model-independent analyses are performed aimed at searching for the presence of new states and establishing the quantum numbers of previously observed charmed meson resonances. In particular the resonance parameters and quantum numbers are determined for the D-1 (2420), D-1 (2430), D-0 (2550), D-1* (2600), D-2 (2740) and D-3*(2750) states. The mixing between the D-1 (2420) and D-1 (2430) resonances is studied and the mixing parameters are measured. The dataset corresponds to an integrated luminosity of 4.7 fb(-1), collected in proton-proton collisions at center-of-mass energies of 7, 8 and 13 TeV with the LHCb detector.
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Molina, R., Doring, M., & Oset, E. (2016). Determination of the compositeness of resonances from decays: The case of the B-s(0) -> J/Psi f(1)(1285). Phys. Rev. D, 93(11), 114004–10pp.
Abstract: We develop a method to measure the amount of compositeness of a resonance, mostly made as a bound state of two hadrons, by simultaneously measuring the rate of production of the resonance and the mass distribution of the two hadrons close to threshold. By using different methods of analysis we conclude that the method allows one to extract the value of 1-Z with about 0.1 of uncertainty. The method is applied to the case of the (B) over bar (0)(s) -> J/Psi f(1)(1285) decay, by looking at the resonance production and the mass distribution of K (K) over bar*.
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Pich, A., & Rodriguez-Sanchez, A. (2016). Determination of the QCD coupling from ALEPH tau decay data. Phys. Rev. D, 94(3), 034027–26pp.
Abstract: We present a comprehensive study of the determination of the strong coupling from tau decay, using the most recent release of the experimental ALEPH data. We critically review all theoretical strategies used in previous works and put forward various novel approaches which allow one to study complementary aspects of the problem. We investigate the advantages and disadvantages of the different methods, trying to uncover their potential hidden weaknesses and test the stability of the obtained results under slight variations of the assumed inputs. We perform several determinations, using different methodologies, and find a very consistent set of results. All determinations are in excellent agreement, and allow us to extract a very reliable value for alpha(s)(m(tau)(2)). The main uncertainty originates in the pure perturbative error from unknown higher orders. Taking into account the systematic differences between the results obtained with the contour-improved perturbation theory and fixed-order perturbation theory prescriptions, we find alpha((nf=3))(s) (m(tau)(2)) = 0.328 +/- 0.013 which implies alpha((nf=5))(s) (M-Z(2)) = 0.1197 +/- 0.0015.
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Li, X. Q., Su, F., & Yang, Y. D. (2011). Determination of the strong coupling gB*B pi from semileptonic B -> pi l nu decay. Phys. Rev. D, 83(5), 054019–8pp.
Abstract: According to heavy-meson chiral perturbation theory, the vector form factor f+(q(2)) of exclusive semileptonic decay B -> pi l nu is closely related, at least in the soft-pion region ( i.e., q(2) similar to (m(B) – m(pi))(2)), to the strong coupling g(B*B pi) or the normalized coupling (g)over-cap. Combining the precisely measured q2 spectrum of B -> pi l nu decay by the BABAR and Belle collaborations with several parametrizations of the form factor f +(q(2)), we can extract these couplings from the residue of the form factor at the B* pole, which relies on an extrapolation of the form factor from the semileptonic region to the unphysical point q(2) = m(B*)(2). Comparing the extracted values with the other experimental and theoretical estimates, we can test these various form-factor parametrizations, which differ from each other by the amount of physical information embedded in. It is found that the extracted values based on the Becirevic-Kaidalov, Ball-Zwicky and Bourrely-Caprini-Lellouch parametrizations are consistent with each other and roughly in agreement with the other theoretical and lattice estimates, while the Boyd-Grinstein-Lebed ansatz, featured by a spurious, unwanted pole at the threshold of the cut, gives a neatly larger value.
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