Farvah Mahmoudi
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Research Interests
Farvah Mahmoudi has a total of 134 co-authors. Here are the top co-authors by number of shared publications:
- Alexandre Arbey
Institut National de Physique Nucléaire et de Physique des Particules
43 shared publications - Tobias Huber
Universität Siegen
30 shared publications - Siavash Neshatpour
School of Particles and Accelerators Institute for Research in Fundamental Sciences (IPM) P.O. Box 19395 -5531 Tehran Iran
13 shared publications - Diego Martinez Santos
Universidade da Coruña
11 shared publications - Krishnamoorthy Sridhar
Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai, India
11 shared publications - Siavash Neshatpour
Institut de Physique des 2 Infinis de Lyon, UMR 5822
10 shared publications
Latest Publications
- Open Access
- 10 June 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (6) , 120
Nonlocal form factor of chromomagnetic penguin in B → Kℓ+ℓ− from QCD light-cone sum rules
A bstract: The branching fraction of the B → Kℓ + ℓ − decay has been measured recently by the LHC experiments, showing a deviation from theory predictions based on the Standard Model (SM). A major challenge in achieving a complete SM prediction and interpreting this discrepancy lies in the treatment of nonlocal hadronic effects. In B → Kℓ + ℓ − , these effects are cast in a single nonlocal form factor, a function of squared momentum transfer q 2 to the lepton pair. One of the previously used methods provides this form factor in the region of spacelike momentum transfer, q 2 < 0, matching the result to the hadronic dispersion relation, which is then continued to the physical region. The calculation done so far was a combination of QCD factorisation for hard-gluon contributions with light-cone sum rules (LCSRs) for soft-gluon ones. In this work, we calculate for the first time the complete nonlocal form factor at q 2 < 0 for one of the effective operators, the chromomagnetic operator O 8 g , applying the method of LCSRs with B -meson distribution amplitudes. We compute, both analytically and numerically, the operator-product expansion (OPE) diagrams with hard-gluon exchanges, analyse their structure and hierarchy, and obtain their spectral density entering the LCSR together with soft-gluon contributions. This study paves the way for our next task, a complete calculation of nonlocal B → Kℓ + ℓ − form factor at spacelike q 2 , including the dominant contributions of current-current operators, known as charm-loops.
- 10 June 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (6) , 120
Open AccessNonlocal form factor of chromomagnetic penguin in B → Kℓ+ℓ− from QCD light-cone sum rules
A bstract: The branching fraction of the B → Kℓ + ℓ − decay has been measured recently by the LHC experiments, showing a deviation from theory predictions based on the Standard Model (SM). A major challenge in achieving a complete SM prediction and interpreting this discrepancy lies in the treatment of nonlocal hadronic effects. In B → Kℓ + ℓ − , these effects are cast in a single nonlocal form factor, a function of squared momentum transfer q 2 to the lepton pair. One of the previously used methods provides this form factor in the region of spacelike momentum transfer, q 2 < 0, matching the result to the hadronic dispersion relation, which is then continued to the physical region. The calculation done so far was a combination of QCD factorisation for hard-gluon contributions with light-cone sum rules (LCSRs) for soft-gluon ones. In this work, we calculate for the first time the complete nonlocal form factor at q 2 < 0 for one of the effective operators, the chromomagnetic operator O 8 g , applying the method of LCSRs with B -meson distribution amplitudes. We compute, both analytically and numerically, the operator-product expansion (OPE) diagrams with hard-gluon exchanges, analyse their structure and hierarchy, and obtain their spectral density entering the LCSR together with soft-gluon contributions. This study paves the way for our next task, a complete calculation of nonlocal B → Kℓ + ℓ − form factor at spacelike q 2 , including the dominant contributions of current-current operators, known as charm-loops.
- Open Access
$Λ_b \to Λ$ Form Factors from Light-Cone Sum Rules with $Λ$-Baryon Distribution Amplitudes
We compute the $Λ_b \to Λ$ transition form factors using light-cone sum rules based on $Λ$-baryon distribution amplitudes, including contributions up to twist--6. The analysis is performed for pseudoscalar, vector, and axial-vector $b\to s$ currents and for different choices of the $Λ_b$ interpolating current. We find that only the pseudoscalar interpolating current leads to numerically stable and phenomenologically viable form factors. The resulting form factors are parametrised using a $z$-expansion and applied to the rare decay $Λ_b \to Λ\ell^+ \ell^-$, yielding predictions for branching ratios in the low-$q^2$ region.Open Access$Λ_b \to Λ$ Form Factors from Light-Cone Sum Rules with $Λ$-Baryon Distribution Amplitudes
We compute the $Λ_b \to Λ$ transition form factors using light-cone sum rules based on $Λ$-baryon distribution amplitudes, including contributions up to twist--6. The analysis is performed for pseudoscalar, vector, and axial-vector $b\to s$ currents and for different choices of the $Λ_b$ interpolating current. We find that only the pseudoscalar interpolating current leads to numerically stable and phenomenologically viable form factors. The resulting form factors are parametrised using a $z$-expansion and applied to the rare decay $Λ_b \to Λ\ell^+ \ell^-$, yielding predictions for branching ratios in the low-$q^2$ region. - Open Access
Probing scalar and pseudoscalar new physics using rare kaon decays
Rare kaon decays provide sensitive tests of new physics. In this work, we focus on scalar and pseudoscalar operators, analysing the $K\to π\ell^+\ell^-$ and $K\to \ell^+\ell^-$ decays. We highlight the complementary role of different modes: $K^+\toπ^+\ell^+\ell^-$, in particular the forward-backward asymmetry in the muon channel as a clean probe of scalar effects, the stringent constraints from $K_L\to μ^+μ^-$, and the discovery potential of future measurements of $K_S\to μ^+μ^-$ and $K_L\to π^0 \ell^+\ell^-$. The interplay between charged and neutral modes underscores the complementarity of NA62, the LHCb upgrade, and KOTO-II.Open AccessProbing scalar and pseudoscalar new physics using rare kaon decays
Rare kaon decays provide sensitive tests of new physics. In this work, we focus on scalar and pseudoscalar operators, analysing the $K\to π\ell^+\ell^-$ and $K\to \ell^+\ell^-$ decays. We highlight the complementary role of different modes: $K^+\toπ^+\ell^+\ell^-$, in particular the forward-backward asymmetry in the muon channel as a clean probe of scalar effects, the stringent constraints from $K_L\to μ^+μ^-$, and the discovery potential of future measurements of $K_S\to μ^+μ^-$ and $K_L\to π^0 \ell^+\ell^-$. The interplay between charged and neutral modes underscores the complementarity of NA62, the LHCb upgrade, and KOTO-II. - Open Access
- 3 July 2025
- Published by Elsevier in Nuclear Physics B
- Vol. 1018
The LHC has ruled out supersymmetry – really?
- 3 July 2025
- Published by Elsevier in Nuclear Physics B
- Vol. 1018
Open AccessThe LHC has ruled out supersymmetry – really?
- Open Access
- 7 November 2024
- Published by Sissa Medialab Srl
- Vol. 443, 045
Global flavour fits to rare B decay observables
We explore the current status of decays involving $b \to s \ell^+\ell^-$ transitions. The recent LHCb update on measurements of $R_K$ and $R_{K^*}$ indicates compatibility with the Standard Model, restricting potential contributions from new physics to adhere to lepton flavour universality. In addition to the latest LHCb measurements of $R_K$ and $R_{K^*}$, we incorporate recent CMS measurements of both $R_K$ and the branching ratio of $B^+ \to K^+ \mu^+\mu^-$. Our analysis adopts a model-independent approach to scrutinise the $b\to s \ell^+ \ell^-$ data, examining the implications of various sets of observables. Furthermore, we explore multi-dimensional fits, assessing the significance of more complex new physics scenarios in comparison to simpler one- and two-dimensional scenarios.- 7 November 2024
- Published by Sissa Medialab Srl
- Vol. 443, 045
Open AccessGlobal flavour fits to rare B decay observables
We explore the current status of decays involving $b \to s \ell^+\ell^-$ transitions. The recent LHCb update on measurements of $R_K$ and $R_{K^*}$ indicates compatibility with the Standard Model, restricting potential contributions from new physics to adhere to lepton flavour universality. In addition to the latest LHCb measurements of $R_K$ and $R_{K^*}$, we incorporate recent CMS measurements of both $R_K$ and the branching ratio of $B^+ \to K^+ \mu^+\mu^-$. Our analysis adopts a model-independent approach to scrutinise the $b\to s \ell^+ \ell^-$ data, examining the implications of various sets of observables. Furthermore, we explore multi-dimensional fits, assessing the significance of more complex new physics scenarios in comparison to simpler one- and two-dimensional scenarios. - Open Access
Overview of B→K(∗)ℓℓ Theoretical Calculations and Uncertainties
The search for New Physics (NP) beyond the Standard Model (SM) has been a central focus of particle physics, including in the context of B-meson decays involving transitions. These transitions, mediated by flavour-changing neutral currents, are highly sensitive to small NP effects due to their suppression in the SM. While direct searches at colliders have not yet led to NP discoveries, indirect probes through semi-leptonic decays have revealed anomalies in observables such as the branching fraction and the angular observable . In order to assess the observed tensions, it is essential to ensure an accurate SM prediction. In this review, we examine the theoretical basis of the decays, addressing in particular key uncertainties arising from local and non-local form factors. We also discuss the impact of QED corrections to the Wilson coefficients, as well as the effect of CKM matrix elements on the predictions and the tension with the experimental measurements. We discuss the most recent results, highlighting ongoing efforts to refine predictions and to constrain potential signs of NP in these critical decay processes.Open AccessOverview of B→K(∗)ℓℓ Theoretical Calculations and Uncertainties
The search for New Physics (NP) beyond the Standard Model (SM) has been a central focus of particle physics, including in the context of B-meson decays involving transitions. These transitions, mediated by flavour-changing neutral currents, are highly sensitive to small NP effects due to their suppression in the SM. While direct searches at colliders have not yet led to NP discoveries, indirect probes through semi-leptonic decays have revealed anomalies in observables such as the branching fraction and the angular observable . In order to assess the observed tensions, it is essential to ensure an accurate SM prediction. In this review, we examine the theoretical basis of the decays, addressing in particular key uncertainties arising from local and non-local form factors. We also discuss the impact of QED corrections to the Wilson coefficients, as well as the effect of CKM matrix elements on the predictions and the tension with the experimental measurements. We discuss the most recent results, highlighting ongoing efforts to refine predictions and to constrain potential signs of NP in these critical decay processes. - Open AccessOverview of $B \to K^{(*)}\ell \ell$ Theoretical Calculations and UncertaintiesThe search for New Physics (NP) beyond the Standard Model (SM) has been a central focus of particle physics, including in the context of $B$-meson decays involving $b \to s \ell \ell$ transitions. These transitions, mediated by flavour-changing neutral currents, are highly sensitive to small NP effects due to their suppression in the SM. While direct searches at colliders have not yet led to NP discoveries, indirect probes through semi-leptonic decays have revealed anomalies in observables such as the branching fraction $\mathcal{B}(B \to K μμ)$ and the angular observable $P_5'(B \to K^* μμ)$. In order to assess the observed tensions, it is essential to ensure an accurate SM prediction. In this review, we examine the theoretical basis of the $B \to K^{(*)} \ell \ell$ decays, addressing in particular key uncertainties arising from local and non-local form factors. We also discuss the impact of QED corrections to the Wilson coefficients, as well as the effect of CKM matrix elements on the predictions and the tension with the experimental measurements. We discuss the most recent results, highlighting ongoing efforts to refine predictions and to constrain potential signs of NP in these critical decay processes.Open AccessOverview of $B \to K^{(*)}\ell \ell$ Theoretical Calculations and UncertaintiesThe search for New Physics (NP) beyond the Standard Model (SM) has been a central focus of particle physics, including in the context of $B$-meson decays involving $b \to s \ell \ell$ transitions. These transitions, mediated by flavour-changing neutral currents, are highly sensitive to small NP effects due to their suppression in the SM. While direct searches at colliders have not yet led to NP discoveries, indirect probes through semi-leptonic decays have revealed anomalies in observables such as the branching fraction $\mathcal{B}(B \to K μμ)$ and the angular observable $P_5'(B \to K^* μμ)$. In order to assess the observed tensions, it is essential to ensure an accurate SM prediction. In this review, we examine the theoretical basis of the $B \to K^{(*)} \ell \ell$ decays, addressing in particular key uncertainties arising from local and non-local form factors. We also discuss the impact of QED corrections to the Wilson coefficients, as well as the effect of CKM matrix elements on the predictions and the tension with the experimental measurements. We discuss the most recent results, highlighting ongoing efforts to refine predictions and to constrain potential signs of NP in these critical decay processes.
- Open Access
- 27 July 2024
- Published by Springer Nature in The European Physical Journal C
- Vol. 84 (7) , 1-14
Revisiting the averaged annihilation rate of thermal relics at low temperature
We derive a low-temperature expansion of the formula to compute the average annihilation rate $${\langle {\sigma v}\rangle }$$ for dark matter in $${\mathbb {Z}}_2$$ -symmetric models, both in the absence and the presence of mass degeneracy in the spectrum near the dark matter candidate. We show that the result obtained in the absence of mass degeneracy is compatible with the analytic formulae in the literature, and that it has a better numerical behaviour for low temperatures. We also provide as ancillary files two notebooks, which perform the two expansions at any order.- 27 July 2024
- Published by Springer Nature in The European Physical Journal C
- Vol. 84 (7) , 1-14
Open AccessRevisiting the averaged annihilation rate of thermal relics at low temperature
We derive a low-temperature expansion of the formula to compute the average annihilation rate $${\langle {\sigma v}\rangle }$$ for dark matter in $${\mathbb {Z}}_2$$ -symmetric models, both in the absence and the presence of mass degeneracy in the spectrum near the dark matter candidate. We show that the result obtained in the absence of mass degeneracy is compatible with the analytic formulae in the literature, and that it has a better numerical behaviour for low temperatures. We also provide as ancillary files two notebooks, which perform the two expansions at any order. - Open Access
- 28 May 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (5) , 1-48
Gauge SU(2)f flavour transfers
We introduce the idea of flavour transfer from a non-abelian horizontal SU(2)f flavour gauge group embedded in the Standard Model flavour structure. The new flavour vector bosons, in the mass range from the tens of GeV to multi-TeV, do not induce large flavour-changing neutral currents and meson oscillations, which usually provide the dominant constraints on this type of structure. Instead, the main constraints arise from “flavour-transfer” operators that we will study in detail. Several explicit models are presented and their prospects are thoroughly explored, including their phenomenology in the lepton and quark sectors at colliders and lower energy experiments. We perform a complete numerical fit in one such scenario, showing that LHC-based lepton-flavour violating searches are competitive with intensity frontier observables.
- 28 May 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (5) , 1-48
Open AccessGauge SU(2)f flavour transfers
We introduce the idea of flavour transfer from a non-abelian horizontal SU(2)f flavour gauge group embedded in the Standard Model flavour structure. The new flavour vector bosons, in the mass range from the tens of GeV to multi-TeV, do not induce large flavour-changing neutral currents and meson oscillations, which usually provide the dominant constraints on this type of structure. Instead, the main constraints arise from “flavour-transfer” operators that we will study in detail. Several explicit models are presented and their prospects are thoroughly explored, including their phenomenology in the lepton and quark sectors at colliders and lower energy experiments. We perform a complete numerical fit in one such scenario, showing that LHC-based lepton-flavour violating searches are competitive with intensity frontier observables.
- Open Access
- 22 February 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (2) , 1-16
Beyond the Standard Model prospects for kaon physics at future experiments
Rare kaon decays offer a powerful tool for investigating new physics in s → d transitions. Currently, many of the interesting decay modes are either measured with rather large uncertainties compared to their theoretical predictions or have not yet been observed. The future HIKE programme at CERN will provide unprecedented sensitivity to rare kaon decays, allowing for strong constraints on new physics scenarios with lepton flavour universality violation. We present the overall picture that emerges from a study of the different decay modes with a global analysis considering projections based on the HIKE programme, both with and without KOTO-II future measurements. We also highlight the most relevant decays and identify that in addition to the “golden channel”, $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ , the rare $$ {K}_L\to {\pi}^0\ell \overline{\ell} $$ decay, especially in the electron sector offers strong constraints on short-distance physics.- 22 February 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (2) , 1-16
Open AccessBeyond the Standard Model prospects for kaon physics at future experiments
Rare kaon decays offer a powerful tool for investigating new physics in s → d transitions. Currently, many of the interesting decay modes are either measured with rather large uncertainties compared to their theoretical predictions or have not yet been observed. The future HIKE programme at CERN will provide unprecedented sensitivity to rare kaon decays, allowing for strong constraints on new physics scenarios with lepton flavour universality violation. We present the overall picture that emerges from a study of the different decay modes with a global analysis considering projections based on the HIKE programme, both with and without KOTO-II future measurements. We also highlight the most relevant decays and identify that in addition to the “golden channel”, $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ , the rare $$ {K}_L\to {\pi}^0\ell \overline{\ell} $$ decay, especially in the electron sector offers strong constraints on short-distance physics.