Papers by Piotr Chankowski
We point out that the one-loop amplitude of the h 0 → γγ decay is gauge invariant owing to a part... more We point out that the one-loop amplitude of the h 0 → γγ decay is gauge invariant owing to a particular relation between the trilinear couplings and the Higgs boson mass. This relation follows only from the gauge symmetry breaking pattern realized by the potential of the scalar fields and not on its specific form. This allows to justify the seemingly inconsistent calculation of the h 0 → γγ amplitude in the minimal supersymmetric model (MSSM) in which one takes the mass of the lighter Higgs boson from e.g. the one-loop effective potential.
Acta Physica Polonica B, 2022
We report the results of the computation of the order (k F a 0) 2 correction, where k F = 3π 2 ρ ... more We report the results of the computation of the order (k F a 0) 2 correction, where k F = 3π 2 ρ is the Fermi wave vector and a 0 the s-wave scattering length of the repulsive interaction, to the ground-state energy of a mixture of oppositely polarized N a spin 1/2 fermions a of masses m a and N b spin 1/2 fermions b of masses m b (ρ = N/V , N = N a + N b). It is shown that the results of the paper [1] in which the same correction has been computed entirely numerically, using a more traditional approach, can be easily and semianalytically reproduced using the effective field theory technique.
Physical Review B, 2021
The effective field theory approach simplifies the perturbative computation of the ground state e... more The effective field theory approach simplifies the perturbative computation of the ground state energy of the diluted gas of repulsive fermions allowing in the case of the unpolarized system to easily rederive the classic results up to the (kFa0) 2 order (where kF is the system’s Fermi momentum and a0 the s-wave scattering length) and (with more labour) to extend it up to the order (kFa0) 4. The analogous expansion of the ground state energy of the polarized gas of spin 1/2 fermions is known only up to the kFa0 order (where kF stands for kF↑ or kF↓); the order (kFa0) 2 contribution has been computed (analytically) only using a specific (hard-core type) interaction potential. Here we show that the effective field theory method also allows to easily obtain the order (kFa0) 2 correction to the ground state of the polarized gas in a way applicable to all repulsive interactions.
Physical Review B, 2021
The effective field theory approach simplifies the perturbative computation of the ground state e... more The effective field theory approach simplifies the perturbative computation of the ground state energy of the diluted gas of repulsive fermions allowing in the case of the unpolarized system to easily rederive the classic results up to the (k F a 0) 2 order (where k F is the system's Fermi momentum and a 0 the s-wave scattering length) and (with more labour) to extend it up to the order (k F a 0) 4. The analogous expansion of the ground state energy of the polarized gas of spin 1/2 fermions is known only up to the k F a 0 order (where k F stands for k F↑ or k F↓); the order (k F a 0) 2 contribution has been computed (analytically) only using a specific (hard-core type) interaction potential. Here we show that the effective field theory method also allows to easily obtain the order (k F a 0) 2 correction to the ground state of the polarized gas in a way applicable to all repulsive interactions.
Journal of High Energy Physics, 2016
We perform a systematic one-loop renormalization of a general renormalizable Yang-Mills theory co... more We perform a systematic one-loop renormalization of a general renormalizable Yang-Mills theory coupled to scalars and fermions using a regularization scheme with a smooth momentum cutoff Λ (implemented through an exponential damping factor). We construct the necessary finite counterterms restoring the BRST invariance of the effective action by analyzing the relevant Slavnov-Taylor identities. We find the relation between the renormalized parameters in our scheme and in the conventional MS scheme which allow us to obtain the explicit two-loop renormalization group equations in our scheme from the known two-loop ones in the MS scheme. We calculate in our scheme the divergences of two-loop vacuum graphs in the presence of a constant scalar background field which allow us to rederive the two-loop beta functions for parameters of the scalar potential. We also prove that consistent application of the proposed regularization leads to counterterms which, together with the original action, combine to a bare action expressed in terms of bare parameters. This, together with treating Λ as an intrinsic scale of a hypothetical underlying finite theory of all interactions, offers a possibility of an unconventional solution to the hierarchy problem if no intermediate scales between the electroweak scale and the Planck scale exist.
We point out that the one-loop amplitude of the $h^0\rightarrow\gamma\gamma$ decay is gauge invar... more We point out that the one-loop amplitude of the $h^0\rightarrow\gamma\gamma$ decay is gauge invariant owing to a particular relation between the trilinear couplings and the Higgs boson mass. This relation follows only from the gauge symmetry breaking pattern realized by the potential of the scalar fields and not on its specific form. This allows to justify the seemingly inconsistent calculation of the $h^0\rightarrow\gamma\gamma$ amplitude in the minimal supersymmetric model (MSSM) in which one takes the mass of the lighter Higgs boson from e.g. the one-loop effective potential.
We study the contraints on non-flavour-blind soft supersymmetry breaking terms coming from flavou... more We study the contraints on non-flavour-blind soft supersymmetry breaking terms coming from flavour and CP violating processes in the presence of hierarchical Yukawa couplings, and quantify how much these constraints are weakened in the regions of the MSSM parameter space characterized by heavy gauginos and multi-TeV sfermion masses, respectively. We also study the inverted sfermion mass hierarchy scenario in the
Physics Letters B, 1994
Combining the constraints coming from the M W measurements and the unsuccesful search for the Hig... more Combining the constraints coming from the M W measurements and the unsuccesful search for the Higgs boson at LEP we determine in the framework of MSSM the allowed mass regions for the lighter scalar partner of the top quark. For a heavy top quark particularily strong bounds are obtained for low values of tan β ≡ v 2 /v 1 and light bottom squark.
Physical Review Letters, 2001
Modern Physics Letters A, 2015
We point out a possible mechanism by which the electroweak hierarchy problem can be avoided in th... more We point out a possible mechanism by which the electroweak hierarchy problem can be avoided in the low energy effective quantum field theory. Assuming the existence of a UV complete underlying fundamental theory and treating the cutoff scale Λ of the effective field theory as a real physical scale we argue that the hierarchy problem would be solved if the coefficient in front of quadratic divergences vanished at the scale Λ, and if the effective theory mass parameters fixed at Λ by the fundamental theory were hierarchically smaller than Λ itself. While this mechanism most probably cannot work in the Standard Model if the scale Λ is to be close to the Planck scale, we show that it can work in a minimal extension (Conformal Standard Model) proposed recently for a different implementation of conformal symmetry breaking.
Journal of High Energy Physics, 2002
We examine unification of gauge couplings in four dimensional renormalizable gauge theories inspi... more We examine unification of gauge couplings in four dimensional renormalizable gauge theories inspired by the latticized (deconstructed) SM or MSSM in five dimensions. The models are based on replicated gauge groups, spontaneously broken to the diagonal subgroup. The analysis is performed at one-loop level, with the contribution from the heavy vector bosons included, and compared with the analogous results in the SM or MSSM. Unification at or above the diagonal breaking scale is discussed. We find that in the considered class of extensions of the SM(MSSM) unification is possible for a wide range of unification scales and with the similar accuracy as in the SM(MSSM). Unification above the diagonal breaking scale is particularly attractive: it is a consequence of the SM(MSSM) unification, but with the unification scale depending on the number of replications of the gauge group.
Physics Letters B, 2012
The main virtue of the Inert Doublet Model (IDM) is that one of its spinless neutral bosons can p... more The main virtue of the Inert Doublet Model (IDM) is that one of its spinless neutral bosons can play the role of Dark Matter. Assuming that the additional sources of CP violation are present in the form of higher dimensional operator(s) we reexamine the possibility that the model parameters for which the right number density of relic particles is predicted are compatible with the first order phase transition that could lead to electroweak baryogenesis. We find, taking into account recent indications from the LHC and the constraints from the electroweak precision data, that for a light DM (40-60 GeV) particle H 0 and heavy, almost degenerate additional scalars H ± and A 0 this is indeed possible but the two parameters most important for the strength of the phase transition: the common mass of H ± and A 0 and the trilinear coupling of the Higgs-like particle h 0 to DM are strongly constrained. H ± and A 0 must weight less than ∼ 440 GeV if the inert minimum is to be the lowest one and the value of the h 0 H 0 H 0 coupling is limited by the XENON 100 data. We stress the important role of the zero temperature part of the potential for the strength of the phase transition.
Physics Letters B, 2000
We consider a CP-conserving two-Higgs-doublet type II model with a light scalar or pseudoscalar n... more We consider a CP-conserving two-Higgs-doublet type II model with a light scalar or pseudoscalar neutral Higgs boson (h = h 0 or h = A 0) that has no ZZ/W W coupling and, thus, cannot be detected in e + e − → Zh (Higgs-strahlung) or ννh (via W W fusion). Despite sum rules which ensure that the light h must have significant tt or bb coupling, for a wedge of moderate tan β, that becomes increasingly large as m h increases, the h can also escape discovery in both bbh and tth production at a √ s = 500 − 800 GeV e + e − collider (for expected luminosities). If the other
Physics Letters B, 2003
We make a simple observation that if one of the right-chiral neutrinos is very heavy or its Yukaw... more We make a simple observation that if one of the right-chiral neutrinos is very heavy or its Yukawa couplings to the standard lepton doublets are negligible, so that it effectively decouples from the seesaw mechanism, the prediction for the baryon asymmetry of the Universe resulting from leptogenesis depends, apart from the masses M 1 and M 2 of the remaining two right-chiral neutrinos, only on the elementỸ 22 ν of the neutrino Yukawa coupling. For M 2 > ∼ 10M 1 the lower bound on M 1 and also on T reh , resulting from the requirement of 'successful leptogenesis' is then significantly increased compared to the one computed recently by Buchmüller et al. in the most general case. Within the framework of thermal leptogenesis, the only way to lower this limit is then to allow for sufficiently small mass difference M 2 − M 1 .
Physics Letters B, 2000
We derive the renormalization group equations for the neutrino masses and mixing angles in explic... more We derive the renormalization group equations for the neutrino masses and mixing angles in explicit form and discuss the possible classes of their solutions. We identify fixed points in the equations for mixing angles, which can be reached during the evolution for several mass patterns and give sin 2 2θ sol = sin 2 2θ atm sin 2 θ 3 /(sin 2 θ atm cos 2 θ 3 + sin 2 θ 3) 2 , consistently with the present experimental information. Further experimental test of this relation is of crucial interest. Moreover, we discuss the stability of quantum corrections to neutrino mass squared differences. Several interesting mass patterns show stability in the presence of fixed point solutions for the angles.
Precision measurement of Rb can provide important information about the Standard Model and beyond... more Precision measurement of Rb can provide important information about the Standard Model and beyond. SLD has developed a new method for measuring Rb with very high purity. This measurement has the lowest systematic error reported to date and future measurements using this method will likely have the lowest total uncertainty. This paper will be divided into the five sections: introduction, hardware, topological vertexing tag method, results and conclusions. The introduction will discuss the importance of Rb and the problems with other measurement techniques. The hardware section will give a brief description of the SLC/SLD system concentrating on its advantages over LEP. An outlook towards the future of SLD Rb measurements will be included in the conclusions.
Acta Physica Polonica B - ACTA PHYS POL B, 2003
We discuss the origin and phenomenological consequences of the flavour violating couplings of the... more We discuss the origin and phenomenological consequences of the flavour violating couplings of the neutral Higgs bosons to the down-type quarks generated in the minimal supersymmetric standard model (MSSM) for large values of tan beta . We concentrate on the scenario with minimal flavour and CP violation (MFV) and demonstrate the tight correlation of the B0s-bar B0s mass difference with BR(B0s--> mu +mu -) and BR(B0d--> mu +mu -). While the first correlation holds also in the case of non-minimal flavour violation, the second one is specific for the minimal case and can potentially serve as a test of the sources of flavour violation in supersymmetry.
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Papers by Piotr Chankowski