Laura Reina | Pontificia Universidad Javeriana (original) (raw)

Papers by Laura Reina

Research paper thumbnail of Scheme independence of the effective Hamiltonian for b --> sgamma and b --> sg decays

Physics Letters B, 1993

We present a calculation of the effective weak Hamiltonian which governs b → s γ and b → s g tran... more We present a calculation of the effective weak Hamiltonian which governs b → s γ and b → s g transitions in two different renormalization schemes (NDR and HV). In the leading logarithmic approximation, we show that the coefficients of the effective Hamiltonian are scheme independent only when one takes correctly into account the scheme dependence of one-and two-loop diagrams. We demonstrate that in NDR there are contributions which were missed in previous calculations. These contributions are necessary to obtain scheme independent coefficients in the final results.

Research paper thumbnail of Mixing and CP violation in K- and B-mesons: a lattice QCD point of view

Nuclear Physics B, 1992

We have analyzed K°-K°and B°-~°mixing on the basis of the most recent experimental results and th... more We have analyzed K°-K°and B°-~°mixing on the basis of the most recent experimental results and theoretical lattice determination of the relevant matrix elements. We find that a top mass larger than 140 GeV and fB~200 MeV, as suggested by recent lattice calculations, imply a CP-violating asymmetry in B -J/~/i+K~decays much larger than previously estimated. We also report the corresponding theoretical prediction for e'/e, for which rather large experimental and theoretical uncertainties still exist. 0550-3213/92/$05.00 © 1992 -Elsevier Science Publishers B.V. All rights reserved M. Lusignoli et al. / Mixing and CP-uiolation The first stage is dominated by short distances and one can use improved perturbation theory to determine the operator structure and the corresponding Wilson coefficients. The resulting Heft can be reliably constructed, provided the reference momentum scale~.t is not too small.

Research paper thumbnail of Estimates of

Research paper thumbnail of An upgraded analysis of ɛ′/ɛ at the next-to-leading order

European Physical Journal C, 1995

An upgraded analysis of ɛ,x d and ɛ′/ɛ, using the latest determinations of the relevant experimen... more An upgraded analysis of ɛ,x d and ɛ′/ɛ, using the latest determinations of the relevant experimental and theoretical parameters, is presented. Using the recent determination of the top quark mass,m t =(174±17) GeV, our best estimate is ɛ′/ɛ=(3.1±2.5)×10−, which lies in the range given by E731. We describe our detemination of ɛ′/ɛ and make a comparison with other similar studies. A detailed discussion of the matching of the full theory to the effective Hamiltonian, written in terms of lattice operators, is also given.

Research paper thumbnail of The DeltaS = 1 effective hamiltonian including next-to-leading order QCD and QED corrections

Nuclear Physics B, 1994

In this paper we present a calculation of the ∆S = 1 effective weak Hamiltonian including next-to... more In this paper we present a calculation of the ∆S = 1 effective weak Hamiltonian including next-to-leading order QCD and QED corrections. At a scale µ of the order of few GeV, the Wilson coefficients of the operators are given in terms of the renormalization group evolution matrix and of the coefficients computed at a large scale ∼ M W . The expression of the evolution matrix is derived from the two-loop anomalous dimension matrix which governs the mixing of the relevant current-current and penguin operators, renormalized in some given regularization scheme. We have computed the anomalous dimension matrix up to and including order α 2 s and α e α s in two different renormalization schemes, NDR and HV, with consistent results. We give many details on the calculation of the anomalous dimension matrix at two loops, on the determination of the Wilson coefficients at the scale M W and of their evolution from M W to µ. We also discuss the dependence of the Wilson coefficients/operators on the regularization scheme.

Research paper thumbnail of at the next-to-leading order in QCD and QED

Physics Letters B, 1993

We present a new calculation of the CP violation parameter (/¢ The results reported m this paper ... more We present a new calculation of the CP violation parameter (/¢ The results reported m this paper we have been obtained by using the AS= I effective hamdtoman computed at the next-to-leading order, including QCD and QED penguins. The matrix elements of the relevant operators have been taken from lattice QCD, at a scale/t=2 GeV. At this relatively large scale, the perturbattve matchmg between the relevant operators and the corresponding coefficients ~s qmte reliable The effect of the nextto-leading corrections Is to lower the prediction obtained at the leading order, thus favouring the experimental result of E731 We analyze different contributions to the final result and compare the leading and next-to-leading cases.

Research paper thumbnail of palabras dia del profesor

Hoy es un día muy especial. Es un día en el que queremos que ustedes queridos maestros sepan que ... more Hoy es un día muy especial. Es un día en el que queremos que ustedes queridos maestros sepan que son muy importantes para nosotros, que siempre los veremos como esas personas que han dedicado gran parte de su vida en cada de uno de nosotros ''sus alumnos'', que mas que nuestros profesores los vemos como amigos, como esas personas que su objetivo aparte de brindar conocimiento es formarnos como buenas personas con valores, especialmente el amor y el respeto. Quiero aprovechar este momento que me han brindado para recordar a una mujer que siempre quiso lo mejor para cada de uno de nosotros, una maestra impecable, con gran sentido de pertenencia por el ITOS. Que quiso este colegio como si fuera su hogar, como una parte de su vida. Que muchas generaciones pasaron por sus manos adquiriendo ese conocimiento y esa sabiduría única en ella. Que a pesar de que haya trascurrido el tiempo, siempre vivirá en nuestros corazones y en el de la familia ITOS. Una mujer que a pesar de los obstáculos que le puso la vida siempre trabajo por el bienestar de cada uno de sus alumnos, que nunca quiso la mediocridad y que siempre busco la excelencia. Una mujer valiente que siempre lucho por el ITOS, como lo es y será LUZ DARY VILLA. Que a pesar de que fuera estricta, siempre nos quiso como sus papis y mamis. Por todo esto quiero que le demos un fuerte aplauso a esa mujer que nos acompaña desde el cielo y siempre vivirá en el alma de la familia ITOS.

Research paper thumbnail of Scheme independence of the effective Hamiltonian for b --> sgamma and b --> sg decays

Physics Letters B, 1993

We present a calculation of the effective weak Hamiltonian which governs b → s γ and b → s g tran... more We present a calculation of the effective weak Hamiltonian which governs b → s γ and b → s g transitions in two different renormalization schemes (NDR and HV). In the leading logarithmic approximation, we show that the coefficients of the effective Hamiltonian are scheme independent only when one takes correctly into account the scheme dependence of one-and two-loop diagrams. We demonstrate that in NDR there are contributions which were missed in previous calculations. These contributions are necessary to obtain scheme independent coefficients in the final results.

Research paper thumbnail of Mixing and CP violation in K- and B-mesons: a lattice QCD point of view

Nuclear Physics B, 1992

We have analyzed K°-K°and B°-~°mixing on the basis of the most recent experimental results and th... more We have analyzed K°-K°and B°-~°mixing on the basis of the most recent experimental results and theoretical lattice determination of the relevant matrix elements. We find that a top mass larger than 140 GeV and fB~200 MeV, as suggested by recent lattice calculations, imply a CP-violating asymmetry in B -J/~/i+K~decays much larger than previously estimated. We also report the corresponding theoretical prediction for e'/e, for which rather large experimental and theoretical uncertainties still exist. 0550-3213/92/$05.00 © 1992 -Elsevier Science Publishers B.V. All rights reserved M. Lusignoli et al. / Mixing and CP-uiolation The first stage is dominated by short distances and one can use improved perturbation theory to determine the operator structure and the corresponding Wilson coefficients. The resulting Heft can be reliably constructed, provided the reference momentum scale~.t is not too small.

Research paper thumbnail of Estimates of

Research paper thumbnail of An upgraded analysis of ɛ′/ɛ at the next-to-leading order

European Physical Journal C, 1995

An upgraded analysis of ɛ,x d and ɛ′/ɛ, using the latest determinations of the relevant experimen... more An upgraded analysis of ɛ,x d and ɛ′/ɛ, using the latest determinations of the relevant experimental and theoretical parameters, is presented. Using the recent determination of the top quark mass,m t =(174±17) GeV, our best estimate is ɛ′/ɛ=(3.1±2.5)×10−, which lies in the range given by E731. We describe our detemination of ɛ′/ɛ and make a comparison with other similar studies. A detailed discussion of the matching of the full theory to the effective Hamiltonian, written in terms of lattice operators, is also given.

Research paper thumbnail of The DeltaS = 1 effective hamiltonian including next-to-leading order QCD and QED corrections

Nuclear Physics B, 1994

In this paper we present a calculation of the ∆S = 1 effective weak Hamiltonian including next-to... more In this paper we present a calculation of the ∆S = 1 effective weak Hamiltonian including next-to-leading order QCD and QED corrections. At a scale µ of the order of few GeV, the Wilson coefficients of the operators are given in terms of the renormalization group evolution matrix and of the coefficients computed at a large scale ∼ M W . The expression of the evolution matrix is derived from the two-loop anomalous dimension matrix which governs the mixing of the relevant current-current and penguin operators, renormalized in some given regularization scheme. We have computed the anomalous dimension matrix up to and including order α 2 s and α e α s in two different renormalization schemes, NDR and HV, with consistent results. We give many details on the calculation of the anomalous dimension matrix at two loops, on the determination of the Wilson coefficients at the scale M W and of their evolution from M W to µ. We also discuss the dependence of the Wilson coefficients/operators on the regularization scheme.

Research paper thumbnail of at the next-to-leading order in QCD and QED

Physics Letters B, 1993

We present a new calculation of the CP violation parameter (/¢ The results reported m this paper ... more We present a new calculation of the CP violation parameter (/¢ The results reported m this paper we have been obtained by using the AS= I effective hamdtoman computed at the next-to-leading order, including QCD and QED penguins. The matrix elements of the relevant operators have been taken from lattice QCD, at a scale/t=2 GeV. At this relatively large scale, the perturbattve matchmg between the relevant operators and the corresponding coefficients ~s qmte reliable The effect of the nextto-leading corrections Is to lower the prediction obtained at the leading order, thus favouring the experimental result of E731 We analyze different contributions to the final result and compare the leading and next-to-leading cases.

Research paper thumbnail of palabras dia del profesor

Hoy es un día muy especial. Es un día en el que queremos que ustedes queridos maestros sepan que ... more Hoy es un día muy especial. Es un día en el que queremos que ustedes queridos maestros sepan que son muy importantes para nosotros, que siempre los veremos como esas personas que han dedicado gran parte de su vida en cada de uno de nosotros ''sus alumnos'', que mas que nuestros profesores los vemos como amigos, como esas personas que su objetivo aparte de brindar conocimiento es formarnos como buenas personas con valores, especialmente el amor y el respeto. Quiero aprovechar este momento que me han brindado para recordar a una mujer que siempre quiso lo mejor para cada de uno de nosotros, una maestra impecable, con gran sentido de pertenencia por el ITOS. Que quiso este colegio como si fuera su hogar, como una parte de su vida. Que muchas generaciones pasaron por sus manos adquiriendo ese conocimiento y esa sabiduría única en ella. Que a pesar de que haya trascurrido el tiempo, siempre vivirá en nuestros corazones y en el de la familia ITOS. Una mujer que a pesar de los obstáculos que le puso la vida siempre trabajo por el bienestar de cada uno de sus alumnos, que nunca quiso la mediocridad y que siempre busco la excelencia. Una mujer valiente que siempre lucho por el ITOS, como lo es y será LUZ DARY VILLA. Que a pesar de que fuera estricta, siempre nos quiso como sus papis y mamis. Por todo esto quiero que le demos un fuerte aplauso a esa mujer que nos acompaña desde el cielo y siempre vivirá en el alma de la familia ITOS.