ENP

Exploring New Physics

 

 

Scientific activities of the various Research Units

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The Standard Model of particle physics has passed a crucial test: the discovery of the Higgs particle along with firstmeasurements of the Higgs couplings. 

The  large hadron collider (LHC) is a fundamental tool to explore the nature of the Higgs boson and the dynamics of electroweak symmetry breaking (EWSB). Indeed the stability of the Higgs potential, the presence of dark matter in the universe and other relevant arguments justify the necessity to study extensions of the Standard Model at the TeV scale in the next LHC runs.

 

Our theoretical research is focused on the experiments that discovered the Higgs particle, now hunting for BSM physics, on possible future colliders such as FCC-ee, CepC, FCC-hh and multi-TeV muon colliders and on a remarkable variety of experiments that are currently running or under realization: a) LHCb, the B physics experiment at LHC; b) other flavour experiments like Belle II at KEK, BES III in Beijing; c) the searches for the rare Kaon decays K -> pi nu nubar at NA62 at CERN and Koto at J-PARC; d) the new E989 experiment, under construction at Fermilab, aiming at improving by a factor 3-4 the precision of the measurement of the muon g-2.

 

Our research will improve our understanding of fundamental interactions and possibly shed light  at discovering New Physics (NP) exploiting both indirect and direct searches. More explicitly, our main objectives are: 

1.     Determining the Standard Model parameters and limits on New Physics 

2.     Unraveling the origin of flavour symmetry breaking and of fermion masses 


3.     Improving our QCD and EW predictions for LHC physics (and future colliders)

4.     Improving our understanding of strong interactions to describe  i) the new discovered exotic states and ii) hadronic form factors 

5.     Investigating New Physics through Astrophysics and Cosmology including also gravitational wave detectors and dark matter searches

 

While the grand objectives above may require long term projects, in the next three years we are confident to achieve the following goals that are fundamental milestones:

 

1.     New Physics searches and Electroweak precision tests: LHC is a fundamental tool to explore the nature of the Higgs boson, the dynamics of EWSB, and the coupling of the Higgs boson to fermion and gauge vectors.

We want to derive constraints on the Standard Model Effective Field Theory (SMEFT) by combining data on electroweak

precision observables, Higgs production and decay, weak gauge boson

scattering, top quark production and decay.

Analyzing LHC data, combined with the Electroweak Precision Observables, is           a powerful tool to discover new physics. 

 

2.     Flavour problem and B anomalies: Flavour physics is crucial to assess the structure of the SM. It Is important to combine and analyze all experimental data to look for NP. Moreover it is important to understand the search possibilities at future facilities. More generally we study flavour models testable in the present and future experiments, addressing also the so-called flavour anomalies, in particular B anomalies. We study favour implications of several extensions of the SM.

 

 

3.     QCD physics for colliders. Our work is  focused on LHC and future colliders phenomenology with the aim to produce the most precise predictions to be tested. We aim to improve the top mass determination.

 

4.     Non-perturbative QCD In many low energy processes a reliable determination of hadronic matrix elements and form factors is required. To this goal we plan to use state-of-the art simulations of lattice QCD, e.g. for kaon-antikaon mixing and leptonic decays of pion, kaon and heavier pseudoscalar mesons. The results will yield important constraints on several well motivated SM extensions.

 

Due to the upcoming result of the muon anomalous magnetic moment from Fermilab it is important to control the hadronic uncertainties, in particular the Light-by-light (HLbL) contribution. To this purpose low energy QCD and short distance constraints have to be fully under control; in 2004 the community has been stirred by a new short distance constraint by Melnikov and Vainshtein and challenged to implement well this behavior. We have shown recentely that holographic QCD gives a nice solution to this problem. 

 

The spectroscopy of charm and bottom presents many states which require to go beyond the standard mesons-baryons picture.

 

5.     Dark matter searches and Astrophysical probes We are investigating   New Physics through Astrophysics, in particular  dark matter.

 

 

 

 

1. New Physics searches and Electroweak precision tests

Given the lack of new physics signals in direct searches at LHC, precision flavour and electroweak physics is playing a crucial role in the quest for NP in the 2020's. The Rome1 RU is very active in both flavour and electroweak phenomenology, from fits to electroweak precision observables to global analyses in the Standard Model Effective Theory (SMEFT). The HEPfit code, featuring state-of-the-art calculations in both flavour and electroweak phenomenology, has been developed by our group. Recently, we have enlarged the scope of our activity to include Machine Learning (ML) techniques for phenomenological purposes. RU: Sezione di Roma I  

 

We want to exploit the precise knowledge of the lepton content of the proton, that we have recently obtained, to predict the rate of the rare lepton initiated high energy processes in the Standard Model and Beyond and that could be measured in the proton proton collisions at the LHC. RU: Sezione di Napoli  

 

Fixed-target experiments, such as the PADME experiment at Frascati National Laboratories, thought built to search for dark photons,  can also search for axion-like particles (ALPs): we aim at predicting the reach of PADME to search for ALPs in a number of BSM scenarios. We shall explore production of BSM exotic particles, like an exotic quark of charge 5/3,  at ATLAS and CMS. 

RU: Sezione LNF

 

Roma Tor Vergata will investigate i) the theoretical and phenomenological

properties viable models with non-trivial UV fixed points and possible

astrophysical implications and ii) a new mechanism of dynamical generation of

the elementary particles masses and the electroweak scale as well as its

phenomenological implications about the scale and the main features of NP. 

RU: Sezione Roma Tor Vergata

 

2.     Flavour problem

The status of flavour physics  is characterized by an overall confirmation of the CKM paradigm and by several two-three sigma tensions (flavor anomalies). We want to investigate flavor  models addressing this experimental situation. 

 

We want to improve the CKM determination ameliorating  the relevant QCD form factors in several phase space regions.  We plan to continue to combine the theoretical and  experimental results in flavor physics, within the UTfit collaboration. RU: Sezione di Roma I

 

Also In the kaon sector NA62, Koto and LHCB experiments will shed light on flavor issues: it is mandatory to explore fully all kaon decays in order to  provide important information on CP violation, new physics and chiral dynamics. We will keep collaboration in the Particle Data Group. RU: Sezione di Napoli

 

3.     QCD physics for colliders  

We will tackle the top-mass measurements at the LHC, the interpetation 

of the measurements in terms of the pole mass, as well as the theoretical 

uncertainties, taking particular care about the error due to bottom 

fragmentation in top decays. For this purpose, we plan to use recent 

NNLO calculations to study bottom fragmentation at NNLO, 

possibly accounting for collinear and soft resummation in the NNLL 

approximation. We shall first explore b-quark and B-hadron production 

in electron-positron annihilation, and then apply the computation to 

top decays.  We shall also work on improving the theoretical accuracy of 

the Standard Model Higgs-production inclusive rate 

and the Higgs+jet cross section.  RU: Sezione LNF  

 

Many processes relevant for LHC will be extensively studied, in particular the master integrals of the non-planar topologies (planar topologies are already analyzed) which appear in the massive corrections to di-photon and di-jet production in hadronic collisions and those appearing in the two-loop light-fermion electroweak corrections to the production of a Higgs boson with a jet.

Moreover the real-virtual NNLO QCD corrections in heavy-to-light quark transition (semileptonic b decays) will be studied. RU: Sezione di Roma I

 

We plan to compute fully differential cross sections for relevant processes at the 

LHC including higher order correction, and in particular mixed QCD-EW corrections that once combined with the accurate measurements ongoing by ATLAS and CMS will provide further stringent tests of the Standard Model.

We want to strength our activity in support of new physics searches at the intensity frontier by performing dedicated analyses using our (publicly available) tool MadDump for present and future experiments in which the production and detection places of possible new weakly interacting

particles are separated by a large distance. RU: Sezione di Napoli

 

 

 

4.     Non-perturbative QCD   

In many low energy processes in order to tag a deviation form the standard model, a reliable determination of hadronic matrix elements are required. Unfortunately these are not always available, in particular are not clear the uncertainties of the estimates. A first principle approach relies on numerical QCD calculation. We plan to continue our research on  multiquark states. 

RU: Sezione Roma I

Theoretical determinations of the kaon-mixing matrix element, combined with the experimental measurements of the indirect CP-violation parameter epsilon_K, allow to constrain the CP-violating phase in the SM, and unveil evidence of possible BSM physics. Tor Vergata  unit is now working to improve to relevant hadronic matrix elements within and beyond the SM. 

RU: Sezione Roma Tor Vergata

 

We are  further investigating how to control the hadronic uncertainties for the g-2 of the muon and exploiting  the nice theoretical properties of holographic QCD (HQCD).    Having shown how HQCD satisfies Melnikov and Vainshtein constraint with an infinite tower of massive axial-vectors, we are investigating possible role of other mesonic states, e.g. scalar and pseudoscalars, as debated still in the recent literature. RU: Sezione di Napoli

 

 

 

 

5.     Dark matter searches and Astrophysical probes

In the last years the possibility of testing New Physics trough Astrophysics searches became of great importance. In particular we will continue to study the possible origin of dark matter and the properties of his interaction with normal matter. 

We will also include gravitational waves (and the corresponding experimental facilities) as further means to constraint and investigate scenarios beyond the SM. RU: Sezione Roma I and Roma Tor Vergata