Pub Date : 2021-03-29DOI: 10.5506/APhysPolB.53.7-A1
N. Kan, Koichiro Kobayashi, Kiyoshi Shiraishi
By projecting the partition function on the “color”-singlet state, we investigate the Hosotani mechanism in the fermion-gauge boson plasma. The present toy-model analysis of the one-loop effective potential at finite temperature shows that the critical temperature of gauge symmetry breaking increases at higher temperature in the smaller volume.
{"title":"Hosotani Mechanism in the “Color”-singlet Plasma","authors":"N. Kan, Koichiro Kobayashi, Kiyoshi Shiraishi","doi":"10.5506/APhysPolB.53.7-A1","DOIUrl":"https://doi.org/10.5506/APhysPolB.53.7-A1","url":null,"abstract":"By projecting the partition function on the “color”-singlet state, we investigate the Hosotani mechanism in the fermion-gauge boson plasma. The present toy-model analysis of the one-loop effective potential at finite temperature shows that the critical temperature of gauge symmetry breaking increases at higher temperature in the smaller volume.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46193501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-25DOI: 10.5506/APhysPolB.53.1-A2
A. Korchin, V. Kovalchuk
The differential rate of the decay of the Higgs boson (h) to a pair of τ leptons with their subsequent decay in the τ− → π−ντ and τ → πν̄τ channels is studied. The Yukawa interaction between the Higgs boson and the τ leptons is assumed to include scalar (S) and pseudoscalar (PS) couplings. Angular distributions of the pions in the h → ττ → π−ντ πν̄τ decay are considered. For real values of the S and PS couplings, this decay is known to be a source of information on CP violation in the hττ interaction. In the present paper, the main attention is paid to a possible non-Hermiticity of this interaction. Influence of non-Hermiticity on the distribution of the angle between planes of the τ− → π−ντ and τ → πν̄τ decays, and distribution of the polar angle of one of the pions are analyzed. Asymmetries sensitive to parameters of CP violation and non-Hermiticity of hττ interaction are proposed.
{"title":"Decay of the Higgs Boson (hto tau ^- tau ^+to pi ^-nu _{tau }pi ^+{bar nu }_tau ) for a Non-Hermitian Yukawa Interaction","authors":"A. Korchin, V. Kovalchuk","doi":"10.5506/APhysPolB.53.1-A2","DOIUrl":"https://doi.org/10.5506/APhysPolB.53.1-A2","url":null,"abstract":"The differential rate of the decay of the Higgs boson (h) to a pair of τ leptons with their subsequent decay in the τ− → π−ντ and τ → πν̄τ channels is studied. The Yukawa interaction between the Higgs boson and the τ leptons is assumed to include scalar (S) and pseudoscalar (PS) couplings. Angular distributions of the pions in the h → ττ → π−ντ πν̄τ decay are considered. For real values of the S and PS couplings, this decay is known to be a source of information on CP violation in the hττ interaction. In the present paper, the main attention is paid to a possible non-Hermiticity of this interaction. Influence of non-Hermiticity on the distribution of the angle between planes of the τ− → π−ντ and τ → πν̄τ decays, and distribution of the polar angle of one of the pions are analyzed. Asymmetries sensitive to parameters of CP violation and non-Hermiticity of hττ interaction are proposed.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45579610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We calculated the cross section of double electron-positron pair production with two-electron capture for the collisions of Pb+Pb ions and we did our calculations at LHC energies. We applied a similar methodology for the calculation of bound-free electron-positron pair production. We used perturbation theory and implemented Monte Carlo integration techniques to calculate the lowest order Feynman diagrams. We also compared our double electron-positron pair production with two-electron capture cross section results obtained in the literature. These calculations may help us to learn more about strong QED.
{"title":"Double Electron–Positron Pair Production with Two-electron Capture in Relativistic Heavy-ion Collisions","authors":"M. Y. Şengül","doi":"10.5506/APHYSPOLB.52.99","DOIUrl":"https://doi.org/10.5506/APHYSPOLB.52.99","url":null,"abstract":"We calculated the cross section of double electron-positron pair production with two-electron capture for the collisions of Pb+Pb ions and we did our calculations at LHC energies. We applied a similar methodology for the calculation of bound-free electron-positron pair production. We used perturbation theory and implemented Monte Carlo integration techniques to calculate the lowest order Feynman diagrams. We also compared our double electron-positron pair production with two-electron capture cross section results obtained in the literature. These calculations may help us to learn more about strong QED.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70739688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-15DOI: 10.5506/APHYSPOLB.52.243
J. Cruz-Martinez, S. Forte, E. Nocera
We discuss a test of the generalization power of the methodology used in the determination of parton distribution functions (PDFs). The "future test" checks whether the uncertainty on PDFs, in regions in which they are not constrained by current data, are compatible with future data. The test is performed by using the current optimized methodology for PDF determination, but with a limited dataset, as available in the past, and by checking whether results are compatible within uncertainty with the result found using a current more extensive dataset. We use the future test to assess the generalization power of the NNPDF4.0 unpolarized PDF and the NNPDFpol1.1 polarized PDF methodology. Specifically, we investigate whether the former would predict the rise of the unpolarized proton structure function $F_2$ at small $x$ using only pre HERA data, and whether the latter would predict the so-called "proton spin crisis" using only pre-EMC data.
{"title":"Future Tests of Parton Distributions","authors":"J. Cruz-Martinez, S. Forte, E. Nocera","doi":"10.5506/APHYSPOLB.52.243","DOIUrl":"https://doi.org/10.5506/APHYSPOLB.52.243","url":null,"abstract":"We discuss a test of the generalization power of the methodology used in the determination of parton distribution functions (PDFs). The \"future test\" checks whether the uncertainty on PDFs, in regions in which they are not constrained by current data, are compatible with future data. The test is performed by using the current optimized methodology for PDF determination, but with a limited dataset, as available in the past, and by checking whether results are compatible within uncertainty with the result found using a current more extensive dataset. We use the future test to assess the generalization power of the NNPDF4.0 unpolarized PDF and the NNPDFpol1.1 polarized PDF methodology. Specifically, we investigate whether the former would predict the rise of the unpolarized proton structure function $F_2$ at small $x$ using only pre HERA data, and whether the latter would predict the so-called \"proton spin crisis\" using only pre-EMC data.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43597738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-13DOI: 10.5506/APhysPolB.52.277
J. Rafelski, Cheng-Tao Yang
Muon abundance is required for the understanding of several fundamental questions regarding properties of the primordial Universe. In this paper we evaluate the production and decay rates of muons in the cosmic plasma as a function of temperature. This allows us to determine when exactly the muon abundance disappears. When the Universe cools below the temperature $kT_mathrm{disappear}approx 4.135$ MeV the muon decay rate overwhelms production rates and muons vanish quasi-instantaneously from the Universe. Interestingly, we show that at $T_mathrm{disappear}$ the muon number is nearly equal to baryon abundance.
{"title":"The Muon Abundance in the Primordial Universe","authors":"J. Rafelski, Cheng-Tao Yang","doi":"10.5506/APhysPolB.52.277","DOIUrl":"https://doi.org/10.5506/APhysPolB.52.277","url":null,"abstract":"Muon abundance is required for the understanding of several fundamental questions regarding properties of the primordial Universe. In this paper we evaluate the production and decay rates of muons in the cosmic plasma as a function of temperature. This allows us to determine when exactly the muon abundance disappears. When the Universe cools below the temperature $kT_mathrm{disappear}approx 4.135$ MeV the muon decay rate overwhelms production rates and muons vanish quasi-instantaneously from the Universe. Interestingly, we show that at $T_mathrm{disappear}$ the muon number is nearly equal to baryon abundance.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41511163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-10DOI: 10.5506/APhysPolB.52.125
M. Sanctis
A general procedure of local reduction for the Dirac equation is introduced to study one- and n-body interacting systems. In the one-body case we show that the reduction allows for an approximate solution of the Dirac equation, correlating the upper and the lower components of the wave function. The two-body case is studied in more detail. We show that the method prevents from introducing spurious, unphysical states. The reduction is also applied to another relativistic equation. Finally, the method is used to construct a specific model in order to study the Charmonium spectrum.
{"title":"A Local Reduction of the Dirac Equation Applied to the Study of Quark Interactions","authors":"M. Sanctis","doi":"10.5506/APhysPolB.52.125","DOIUrl":"https://doi.org/10.5506/APhysPolB.52.125","url":null,"abstract":"A general procedure of local reduction for the Dirac equation is introduced to study one- and n-body interacting systems. In the one-body case we show that the reduction allows for an approximate solution of the Dirac equation, correlating the upper and the lower components of the wave function. The two-body case is studied in more detail. We show that the method prevents from introducing spurious, unphysical states. The reduction is also applied to another relativistic equation. Finally, the method is used to construct a specific model in order to study the Charmonium spectrum.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47389030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-22DOI: 10.5506/APhysPolB.52.1007
F. Klinkhamer
In this review article, we first discuss a possible regularization of the big bang curvature singularity of the standard Friedmann cosmology, where the curvature singularity is replaced by a spacetime defect. We then consider the hypothesis that a new physics phase gave rise to this particular spacetime defect. Specifically, we set out on an explorative calculation using the IIB matrix model, which has been proposed as a particular formulation of nonperturbative superstring theory (M-theory).
{"title":"M-theory and the Birth of the Universe","authors":"F. Klinkhamer","doi":"10.5506/APhysPolB.52.1007","DOIUrl":"https://doi.org/10.5506/APhysPolB.52.1007","url":null,"abstract":"In this review article, we first discuss a possible regularization of the big bang curvature singularity of the standard Friedmann cosmology, where the curvature singularity is replaced by a spacetime defect. We then consider the hypothesis that a new physics phase gave rise to this particular spacetime defect. Specifically, we set out on an explorative calculation using the IIB matrix model, which has been proposed as a particular formulation of nonperturbative superstring theory (M-theory).","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41296163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-17DOI: 10.5506/APHYSPOLB.52.203
V. Koch, V. Vovchenko
We report on recent progress concerning theoretical description of event-by-event fluctuations in heavy-ion collisions. Specifically we discuss a new Cooper-Frye particlization routine -- the subensemble sampler -- which is designed to incorporate effects of global conservation laws, thermal smearing and resonance decays on fluctuation measurements in various rapidity acceptances. First applications of the method to heavy-ion collisions at the LHC energies are presented and further necessary steps to analyze fluctuations from RHIC beam energy scan are outlined.
{"title":"Exploring the QCD Phase Diagram with Fluctuations","authors":"V. Koch, V. Vovchenko","doi":"10.5506/APHYSPOLB.52.203","DOIUrl":"https://doi.org/10.5506/APHYSPOLB.52.203","url":null,"abstract":"We report on recent progress concerning theoretical description of event-by-event fluctuations in heavy-ion collisions. Specifically we discuss a new Cooper-Frye particlization routine -- the subensemble sampler -- which is designed to incorporate effects of global conservation laws, thermal smearing and resonance decays on fluctuation measurements in various rapidity acceptances. First applications of the method to heavy-ion collisions at the LHC energies are presented and further necessary steps to analyze fluctuations from RHIC beam energy scan are outlined.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42817598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-15DOI: 10.5506/APhysPolB.52.953
Rebeca Gonzalez Suarez
Long-lived particles have significant enough lifetimes as to, when produced in collisions, leave a distinct signature in the detectors. Driven by increasingly higher energies, trigger and reconstruction algorithms at particle colliders are optimized for increasingly heavier particles, which in turn, tend to be short-lived. This makes searches for long-lived particles difficult, usually requiring dedicated methods and sometimes dedicated hardware top spot them. However, taking upon the challenge brings enormous potential, since new, long-lived particles feature in a variety of promising new physics models that could answer most of the open questions of the standard model, such as: neutrino masses, Dark Matter, or the matter-antimatter unbalance in the Universe.
{"title":"Long-lived Particles at Future Colliders","authors":"Rebeca Gonzalez Suarez","doi":"10.5506/APhysPolB.52.953","DOIUrl":"https://doi.org/10.5506/APhysPolB.52.953","url":null,"abstract":"Long-lived particles have significant enough lifetimes as to, when produced in collisions, leave a distinct signature in the detectors. Driven by increasingly higher energies, trigger and reconstruction algorithms at particle colliders are optimized for increasingly heavier particles, which in turn, tend to be short-lived. This makes searches for long-lived particles difficult, usually requiring dedicated methods and sometimes dedicated hardware top spot them. However, taking upon the challenge brings enormous potential, since new, long-lived particles feature in a variety of promising new physics models that could answer most of the open questions of the standard model, such as: neutrino masses, Dark Matter, or the matter-antimatter unbalance in the Universe.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43552594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-05DOI: 10.5506/APhysPolB.52.1239
J. Kyzioł, Andrzej Okni'nski
We study the Duffing equation and its generalizations with polynomial nonlinearities. Recently, we have demonstrated that metamorphoses of the amplitude response curves, computed by asymptotic methods in implicit form as F (Ω, A) = 0, permit prediction of qualitative changes of dynamics occurring at singular points of the implicit curve F (Ω, A) = 0. In the present work we determine a global structure of singular points of the amplitude profiles computing bifurcation sets, i.e. sets containing all points in the parameter space for which the amplitude profile has a singular point. We connect our work with independent research on tangential points on amplitude profiles, associated with jump phenomena, characteristic for the Duffing equation. We also show that our techniques can be applied to solutions of form Ω± = f± (A), obtained within other asymptotic approaches.
{"title":"Duffing-type Equations: Singular Points of Amplitude Profiles and Bifurcations","authors":"J. Kyzioł, Andrzej Okni'nski","doi":"10.5506/APhysPolB.52.1239","DOIUrl":"https://doi.org/10.5506/APhysPolB.52.1239","url":null,"abstract":"We study the Duffing equation and its generalizations with polynomial nonlinearities. Recently, we have demonstrated that metamorphoses of the amplitude response curves, computed by asymptotic methods in implicit form as F (Ω, A) = 0, permit prediction of qualitative changes of dynamics occurring at singular points of the implicit curve F (Ω, A) = 0. In the present work we determine a global structure of singular points of the amplitude profiles computing bifurcation sets, i.e. sets containing all points in the parameter space for which the amplitude profile has a singular point. We connect our work with independent research on tangential points on amplitude profiles, associated with jump phenomena, characteristic for the Duffing equation. We also show that our techniques can be applied to solutions of form Ω± = f± (A), obtained within other asymptotic approaches.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44687813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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