arXiv subjects

Sumit Banik

Publications and source records attributed to Sumit Banik.

At least 19 recordsLinked to original sources

arXiv2026

HyperPrecision: A Mathematica package for High-Precision Numerical Evaluation of Multivariate Hypergeometric Functions

In this paper, we present HyperPrecision, a Mathematica package for high-precision numerical evaluation of general Horn-type multivariate hypergeometric functions and their Laurent expansions in a small parameter $\epsilon$. Such functions appear widely in physics and mathematics, with applications ranging from quantum field theory and string theory to number theory and statistics. Their high-precision numerical evaluation, however, remains challenging, since their defining series converge only in restricted domains and analytic continuation beyond these domains is, in general, non-trivial. HyperPrecision addresses this problem by automatically constructing the Pfaffian system of partial differential equations for a given hypergeometric function and restricting it to a one-dimensional contour in the space of variables connecting the starting to the target point. The resulting ordinary differential equation is then solved by the Frobenius method, with boundary conditions fixed analytically by the defining series. We illustrate the use of the package by evaluating commonly occurring multivariate hypergeometric functions, including the Appell $F_1$, $F_2$, $F_3$, and $F_4$ functions, the Horn $G$- and $H$-series, and the Lauricella $F_A$, $F_B$, $F_C$, and $F_D$ functions, as well as by considering applications to angular integrals, Feynman integrals, and cosmological and holographic correlators.

hep-ph↗

arXiv2026

Indications for New Higgs Bosons

After the Higgs discovery, the question of whether particles beyond those of the Standard Model exist is more pressing than ever. In this context, the scalar sector is particularly promising, since it lies at the core of the internal problems of the Standard Model, while extensions of it allow us to resolve them and can provide explanations for Dark matter, non-zero neutrino masses, inflation etc. In these proceedings, we review the indications for new Higgs bosons at the electroweak scale with masses of $\approx$95 GeV and $\approx$152 GeV. These excesses are most significant in the di-photon channel but are supported by weaker-than-expected limits in other decay modes. While for the 95 GeV candidate the production mechanism is mostly unknown, the (hypothetical) 152 GeV Higgs is dominantly produced in association with leptons, $(b)$ jets and missing energy, pointing towards the Drell-Yan production of an $SU(2)_L$ triplet with $Y=0$. Interestingly, this model predicts $t\to H^\pm b$ with $H^\pm\to WZ$, which resembles the signature of $t\bar{t}Z$ production in the Standard Model and is in fact preferred by current data. Finally, we investigate the possibility that the significant tensions between the Standard Model predictions and the measurements in differential top-quark distributions are due to contamination from new physics involving both the 152 GeV and the 95 GeV scalar.

hep-ph↗

arXiv2025

Multiple Mellin-Barnes integrals with polygamma functions

Mellin-Barnes (MB) integrals appear in various branches of physics and mathematics and are, in particular, used as a standard tool for evaluating multi-loop, multi-scale Feynman integrals both analytically and numerically. Recent geometric approaches based on conic hulls and triangulations provide a systematic framework for computing multiple MB integrals in terms of multivariate series. These approaches have so far been limited to MB integrals whose integrands are ratios of products of Euler's gamma functions only. However, in Feynman integral calculus, MB integrals with polygamma functions naturally arise, for instance, after resolving singularities in the dimensional-regularisation parameter $\epsilon$ and expanding the MB integrand in powers of $\epsilon$, as done by the public codes MB.m and MBresolve.m. In this paper, we extend the conic hull and triangulation methods to the computation of MB integrals having polygamma functions in their integrand. We show that the arguments of polygamma functions can be treated in a similar way to the arguments of gamma functions when applying the conic hull and triangulation techniques to identify poles that would contribute to different series solutions. However, since the singularity structure of the polygamma function is different from that of the gamma function, we propose two different ways to compute MB integrals involving polygamma functions, depending on whether the MB integral has straight or non-straight contours. We have implemented these algorithms in an updated version of the Mathematica package MBConicHulls.wl, which can be found at https://github.com/SumitBanikGit/MBConicHulls/, and we illustrate their use with a set of examples from Feynman integral calculus.

hep-ph↗

arXiv2025

Sunset integrals with up to three mass scales in chiral perturbation theory: a comparative study of the Mellin-Barnes representation technique

Sunset integrals are among the simplest of two-loop integrals that appear in perturbative quantum field theories and possess up to four distinct mass scales. By means of integration by parts identities, they can be written in terms of four distinct master integrals. In this article, we discuss the independent configurations of on-shell and off-shell sunset master integrals with one, two and three mass scales that arise in chiral perturbation theory. We derive Mellin-Barnes integral representations of these integrals and analytically solve them using various methods to obtain exact results in the form of single and double convergent series of the hypergeometric type, for the values of the mass parameters that allow us to do so. We then discuss how to analytically continue the results to other regions of the parameters and conclude by discussing a few applications in chiral perturbation theory.

hep-ph↗

arXiv2025

Two-loop anomalous dimensions for baryon-number-violating operators in SMEFT

We compute the two-loop renormalization-group equations for the baryon-number-violating dimension-six operators in the SMEFT. This includes all three gauge interactions, the Yukawa, and Higgs self-interaction contributions. In addition, we present the one-loop matching of the $S_1$ scalar leptoquark on the SMEFT, which can generate the Wilson coefficients of all four gauge-invariant baryon-number-violating SMEFT operators. Using this example, we demonstrate the cancellation of scheme and matching-scale dependences. Together with the known two-loop renormalization-group evolution below the electroweak scale in the LEFT, as well as the one-loop matching of SMEFT onto LEFT, our results enable consistent next-to-leading-log analyses of nucleon decays, provided that the relevant matrix elements are known at next-to-leading-order accuracy.

hep-ph↗

arXiv2025

Reinterpretation and preservation of data and analyses in HEP

Data from particle physics experiments are unique and are often the result of a very large investment of resources. Given the potential scientific impact of these data, which goes far beyond the immediate priorities of the experimental collaborations that obtain them, it is imperative that the collaborations and the wider particle physics community publish and preserve sufficient information to ensure that this impact can be realised, now and into the future. The information to be published and preserved includes the algorithms, statistical information, simulations and the recorded data. This publication and preservation requires significant resources, and should be a strategic priority with commensurate planning and resource allocation from the earliest stages of future facilities and experiments.

hep-ph↗

arXiv2024

Correlating $A \to \gamma\gamma$ with electric dipole moments in the two Higgs doublet model in light of the diphoton excesses at 95 GeV and 152 GeV

We examine the correlations between new scalar boson decays to photons and electric dipole moments (EDMs) in the CP-violating flavor-aligned two-Higgs-doublet model (2HDM). It is convenient to work in the Higgs basis $\{{H}_1, {H}_2\}$ where only the first Higgs doublet field ${H}_1$ acquires a vacuum expectation value. In light of the LHC Higgs data, which agree well with Standard Model (SM) predictions, it follows that the parameters of the 2HDM are consistent with the Higgs alignment limit. In this parameter regime, the observed SM-like Higgs boson resides almost entirely in ${H}_1$, and the other two physical neutral scalars, which reside almost entirely in ${H}_2$, are approximate eigenstates of CP (denoted by the CP-even $H$ and the CP-odd $A$). In the Higgs basis, the scalar potential term $\bar{Z}_7 {H}_1^\dagger {H}_2 {H}_2^\dagger {H}_2+{\rm h.c.}$ governs the charged-Higgs loop contributions to the decay of $H$ and $A$ to photons. If $ \text{Re } \bar{Z}_7 \, \text{Im } \bar{Z}_7 \neq 0$, then CP-violating effects are present and allow for an $H^+ H^- A$ coupling, which can yield a sizable branching ratio for $A\to\gamma\gamma$. These CP-violating effects also generate non-zero EDMs for the electron, the neutron and the proton. We examine these correlations for the cases of $m_{A}=95$ GeV and $m_{A}=152$ GeV where interesting excesses in the diphoton spectrum have been observed at the LHC. These excesses can be explained via the decay of $A$ while being consistent with the experimental bound for the electron EDM in regions of parameter space that can be tested with future neutron and proton EDM measurements. This allows for the interesting possibility where the 95 GeV diphoton excess can be identified with $A$, while $m_H\simeq 98$ GeV can account for the best fit to the LEP excess in $e^+e^-\to ZH$ with $H\to b\bar b$.

hep-ph↗

arXiv2024

Anatomy of the Real Higgs Triplet Model

In this article, we examine the Standard Model extended by a $Y=0$ real Higgs triplet, the $\Delta$SM. It contains a $CP$-even neutral Higgs ($\Delta^0$) and two charged Higgs bosons ($\Delta^\pm$), which are quasi-degenerate in mass. We first study the theoretical constraints from vacuum stability and perturbative unitarity and then calculate the Higgs decays, including the loop-induced modes such as di-photons ($\gamma\gamma$) and $Z\gamma$. In the limit of a small mixing between the SM Higgs and $\Delta^0$, the latter decays dominantly to $WW$ and can have a sizable branching ratio to di-photon. The model predicts a positive definite shift in the $W$ mass, which agrees with the current global electroweak fit. At the Large Hadron Collider, it leads to a $(i)$ stau-like signature from $pp\to \Delta^+\Delta^-\to \tau^+\tau^-\nu\bar\nu$, $(ii)$ multi-lepton final states from $pp\to \gamma^*\to \Delta^+\Delta^-\to W^+W^-ZZ$ and $pp\to W^{*} \to \Delta^\pm\Delta^0\to W^\pm Z W^+W^-$ as well as $(iii)$ associated di-photon production from $pp\to W^{*} \to \Delta^\pm(\Delta^0\to\gamma\gamma)$. Concerning $(i)$, the reinterpretation of the recent supersymmetric tau partner search by ATLAS and CMS excludes $m_{\Delta^\pm}<110$ GeV at 95% CL. From $(ii)$, some of the signal regions of multi-lepton searches lead to bounds close to the predicted cross-section, but electroweak scale masses are still allowed. For $(iii)$, the recast of the associated di-photon searches by ATLAS and a combined log-likelihood fit of signal and background to data find that out of the 25 signal regions, 10 provide relevant limits on Br$(\Delta^0\to\gamma\gamma)$ at the per cent level. Interestingly, 6 signal regions show excesses at around 152 GeV, leading to a preference for a non-zero di-photon branching ratio of about 0.7% with the corresponding significance amounting to about $4\sigma$.

hep-ph↗

arXiv2024

Analytic Evaluation of Multiple Mellin-Barnes Integrals

We summarize two geometrical approaches to analytically evaluate higher-fold Mellin-Barnes (MB) integrals in terms of hypergeometric functions. The first method is based on intersections of conic hulls, while the second one, which is more recent, relies on triangulations of a set of points. We demonstrate that, once automatized, the triangulation approach is computationally more efficient than the conic hull approach. As an application of this triangulation approach, we describe how one can derive simpler hypergeometric solutions of the conformal off-shell massless two-loop double box and one-loop hexagon Feynman integrals than those previously obtained from the conic hull approach. Lastly, by applying the above techniques on the MB representation of multiple polylogarithms, we show how to obtain new convergent series representations for these functions. These new analytic expressions were numerically cross-checked with GINAC.

hep-th↗

arXiv2024

Explanation of the excesses in associated di-photon production at 152 GeV in 2HDM

Statistically significant excesses exist at around 152 GeV in associated di-photon production ($\gamma\gamma+X$) in the sidebands of SM Higgs analyses of ATLAS (using the full run-2 dataset). They are most pronounced in the single-$\tau$, missing-transverse-energy, four-jet and $\geqslant1\ell+\!\geqslant1b$-jet channels ($\approx3\sigma$) and can be explained by the Drell-Yan production of new Higgs bosons, i.e. $pp\to W^*\to H^\pm H^0$. We first examine the excesses in a simplified model approach, considering that $H^\pm$ decays to $\tau\nu$, $WZ$ or $tb$. Both the $\tau\nu$ and $tb$ decay modes individually lead to a significance of $\lessapprox4\sigma$ while for $WZ$ one can obtain at most $3.5\sigma$. This is because the decays of $WZ$ lead to multiple leptons contributing to the two-lepton channel which does not show an excess at 152 GeV. Next, we consider two-Higgs-doublet models where the charged Higgs does not decay to $WZ$ at tree-level, finding a significance of $\gtrapprox4\sigma$ for a branching ratio of the new neutral Higgs to photons of $\approx$2%. Even though this branching fraction is quite sizable, it can be obtained in composite models or via the Lagrangian term $\lambda_6 H_1^\dagger H_1 H_2^\dagger H_1+{\rm h.c.}$ breaking the commonly imposed $Z_2$ symmetry.

hep-ph↗

arXiv2024

Growing Evidence for a Higgs Triplet

Despite intensive searches at the LHC, no new fundamental particle has been discovered since the discovery of the 125 GeV Higgs boson. In general, a new physics discovery is challenging without a UV-complete model because different channels and observables cannot be combined directly and unambiguously. Moreover, without indirect hints for new particles, the parameter space to be searched is huge, resulting in diminished significance due to the look-elsewhere effect. Several LHC searches with multiple leptons in the final state point towards the existence of a new Higgs boson with a mass in the 140-160 GeV range, decaying mostly to a pair of W bosons. This dominant decay mode motivates a Higgs triplet with zero hypercharge, which also predicts a heavier-than-expected $W$-boson as indicated by the CDF-II measurement. Within this simple and predictive model, we simulate and combine channels of associated di-photon production. Considering the run-2 results of ATLAS, including those presented recently at the Moriond conference, a significance of 4.3$\sigma$ is obtained for a mass of 152 GeV. This is the largest statistical evidence for a new narrow resonance observed at the LHC.

hep-ph↗

arXiv2024

Geometrical methods for the analytic evaluation of multiple Mellin-Barnes integrals

Two recently developed techniques of analytic evaluation of multifold Mellin-Barnes (MB) integrals are presented. Both approaches rest on the definition of geometrical objets conveniently associated with the MB integrands, which can then be used along with multivariate residues analysis to derive series representations of the MB integrals. The first method is based on introducing conic hulls and considering specific intersections of the latter, while the second one rests on point configurations and their regular triangulations. After a brief description of both methods, which have been automatized in the MBConicHulls.wl Mathematica package, we review some of their applications. In particular, we show how the conic hulls method was used to obtain the first analytic calculation of complicated Feynman integrals, such as the massless off-shell conformal hexagon and double-box. We then show that the triangulation method is even more efficient, as it allows one to compute these nontrivial objects and harder ones in a much faster way.

hep-th↗

arXiv2024

Explaining the $\gamma\gamma+X$ Excesses at $\approx$151.5 GeV via the Drell-Yan Production of a Higgs Triplet

The multi-lepton anomalies and searches for the associated production of a narrow resonance indicate the existence of a $\approx$151 GeV Higgs with a significance of $>5\sigma$ and $>3.9\sigma$, respectively. On the one hand, these anomalies require a sizable branching fraction of the new scalar to $WW$, while on the other hand, no $ZZ$ signal at this mass has been observed. This suggests that the new boson is the neutral component of an $SU(2)_L$ triplet with zero hypercharge. This field leads to a positive definite shift in the $W$ mass, as preferred by the current global fit, and is produced via the Drell-Yan process $pp\to W^*\to \Delta^0\Delta^\pm$. We use the side-bands of the ATLAS analysis \cite{ATLAS:2023omk} of the associated production of the Standard Model Higgs in the di-photon channel to search for this production mode of the triplet. Since the dominant decays of $\Delta^\pm$ depend only on its mass, the effect in the 22 signal categories considered by ATLAS is completely correlated. We find that the ones most sensitive to the Drell-Yan production of the triplet Higgs show consistent excesses at a mass of $\approx$151.5 GeV. Combining these channels in a likelihood ratio test, a non-zero Br$[\Delta^0\to\gamma\gamma] = 0.66\%$ is preferred by $\approx$3$\sigma$, supporting our conjecture.

hep-ph↗

arXiv2023

Differential $e\mu bb $ Cross-Sections and New Higgses at the Electroweak Scale

ATLAS found that none of their Standard Model simulations can describe the measured differential lepton distributions in their $t \bar{t}$ analysis reasonably well. Therefore, we study the possibility that this measurement has a new physics contamination. We consider a benchmark model motivated by the indications for di-photon resonances: A heavy scalar decays into two lighter Higgs bosons with masses of 152\,GeV and 95\,GeV, with subsequent decay to $WW$ and $bb$, respectively. In this setup, the description of data is improved by at least $5.6 \sigma$.

hep-ph↗

arXiv2023

Multiple Mellin-Barnes integrals and triangulations of point configurations

We present a novel technique for the analytic evaluation of multifold Mellin-Barnes (MB) integrals, which commonly appear in physics, as for instance in the calculations of multi-loop multi-scale Feynman integrals. Our approach is based on triangulating a set of points which can be assigned to a given MB integral, and yields the final analytic results in terms of linear combinations of multiple series, each triangulation allowing the derivation of one of these combinations. When this technique is applied to the computation of Feynman integrals, the involved series are of the (multivariable) hypergeometric type. We implement our method in the Mathematica package MBConicHulls.wl, an already existing software dedicated to the analytic evaluation of multiple MB integrals, based on a recently developed computational approach using intersections of conic hulls. The triangulation method is remarkably faster than the conic hulls approach and can thus be used for the calculation of higher-fold MB integrals as we show here by computing triangulations for highly complicated objects such as the off-shell massless scalar one-loop 15-point Feynman integral whose MB representation has 104 folds. As other applications we show how this technique can provide new results for the off-shell massless conformal hexagon and double box Feynman integrals, as well as for the hard diagram of the two loop hexagon Wilson loop.

hep-th↗

arXiv2023

Uncovering New Higgses in the LHC Analyses of Differential $t\bar t$ Cross Sections

Statistically significant tensions between the Standard Model (SM) predictions and the measured lepton distributions in differential top cross-sections emerged in LHC Run~1 data and became even more pronounced in Run~2 analyses. Due to the level of sophistication of the SM predictions and the performance of the ATLAS and CMS detectors, this is very remarkable. Therefore, one should seriously consider the possibility that these measurements are contaminated by beyond-the-SM contributions. In this article, we use differential lepton distributions from the latest ATLAS $t\bar t$ analysis to study a new physics benchmark model motivated by existing indications for new Higgses: a new scalar $H$ is produced via gluon fusion and decays to $S^\prime$ ($95\,$GeV) and $S$ ($152\,$GeV), which subsequently decay to $b\bar b$ and $WW$, respectively. In this setup, the total $\chi^2$ is reduced, compared to the SM, resulting in $\Delta\chi^2=34$ to $\Delta\chi^2=158$, depending on the SM simulation used. Notably, allowing $m_S$ to vary, the combination of the distributions points towards $m_S\!\approx\!150\,$GeV which is consistent with the existing $\gamma \gamma$ and $WW$ signals, rendering a mismodelling of the SM unlikely. Averaging the results of the different SM predictions, a non-vanishing cross-section for $pp\to H\to SS^\prime\to b\bar b WW$ of $\approx\!13$pb is preferred. If $S^\prime$ is SM-like, this cross-section, at the same time explains the $95\,$GeV $\gamma\gamma$ excess, while the dominance of $S\to WW$ suggests that $S$ is the neutral component of the $SU(2)_L$ triplet with hypercharge~0.

hep-ph↗

arXiv2023

Renormalization Group Evolution with Scalar Leptoquarks

Leptoquarks are theoretically well-motivated and have received increasing attention in recent years as they can explain several hints for physics beyond the Standard Model. In this article, we calculate the renormalisation group evolution of models with scalar leptoquarks. We compute the anomalous dimensions for all couplings (gauge, Yukawa, Higgs and leptoquarks interactions) of the most general Lagrangian at the two-loop level and the corresponding threshold corrections at one-loop. The most relevant analytic results are presented in the Appendix, while the notebook containing the full expressions can be downloaded at https://github.com/SumitBanikGit/SLQ-RG. In our phenomenological analysis, we consider some exemplary cases with focus on gauge and Yukawa coupling unification.

hep-ph↗

arXiv2023

$SU(2)_L$ triplet scalar as the origin of the 95 GeV excess?

We explore the possibility that an $SU(2)_L$ triplet scalar with hypercharge $Y=0$ is the origin of the $95\,$GeV diphoton excess. For a small mixing angle with the Standard Model Higgs, its neutral component has naturally a sizable branching ratio to $\gamma\gamma$ such that its Drell-Yan production via $pp\to W^*\to H H^\pm$ is sufficient to obtain the desired signal strength, where $H^\pm$ is the charged Higgs component of the triplet. The predictions of this setup are: 1) The $\gamma\gamma$ signal has a $p_T$ spectrum different from gluon fusion but similar to associated production. 2) Photons are produced in association with tau leptons and jets, but generally do not fall into the vector-boson fusion category. 3) The existence of a charged Higgs with $m_{H^\pm}\approx\!(95\pm5)\,$GeV leading to $\sigma(pp\to \tau\tau\nu\nu)\approx0.4\,$pb, which is of the same level as the current limit and can be discovered with Run 3 data. 4) A positive definite shift in the $W$ mass as suggested by the current global electroweak fit.

hep-ph↗