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R. Rosenfeld

Publications and source records attributed to R. Rosenfeld.

At least 91 records · Page 5Linked to original sources
arXiv2001

Cosmological Bounds on an Invisibly Decaying Higgs Boson

We derive bounds on the Higgs boson coupling $g^{\prime}$ to a stable light scalar which is regarded as a collisional dark matter candidate. We study the behaviour of this scalar, that we refer to as phion ($ϕ$), in the early Universe for different ranges of its mass. We find that a phion in the mass range of $100 \mev$ is excluded, while if its mass is about $1 \gev$, a rather large coupling constant, $g^{\prime} \gsim 2$, and $m_h \lsim 130 \gev$ are required in order to avoid overabundance. In the latter case, the invisible decay mode of the Higgs boson is dominant.

astro-ph↗
arXiv2001

Bounds on Direct Couplings of Superheavy Metastable Particles to the Inflaton Field from Ultra High Energy Cosmic Ray Events

Top-down models for the origin of ultra high energy cosmic rays (UHECR's) propose that these events are the decay products of relic superheavy metastable particles, usually called $X$ particles. These particles can be produced in the reheating period following the inflationary epoch of the early Universe. We obtain constraints on some parameters such as the lifetime and direct couplings of the $X$-particle to the inflaton field from the requirement that they are responsible for the observed UHECR flux.

hep-ph↗
arXiv2001

Cosmological Constraints on an Invisibly Decaying Higgs Boson

Working in the context of a proposal for collisional dark matter, we derive bounds on the Higgs boson coupling $g^{\prime}$ to a stable light scalar particle, which we refer to as phion ($ϕ$), required to solve problems with small scale structure formation which arise in collisionless dark matter models. We discuss the behaviour of the phion in the early universe for different ranges of its mass. We find that a phion in the mass range of 100 MeV is excluded and that a phion in the mass range of 1 GeV requires a large coupling constant, $g^{\prime} \gsim 2$, and $m_h \lsim 130$ GeV in order to avoid overabundance, in which case the invisible decay mode of the Higgs boson would be dominant.

hep-ph↗
arXiv2001

Estimating sigma-meson couplings from D \to 3πdecays

Using recent experimental evidence from E791 on the sigma meson in D \to 3πdecays, we study the relevant couplings in D \to σπand σ\to π pi within the accepted theoretical framework for non leptonic D decays. We also review the linear sigma model, finding that it gives a description which is consistent with the experimental data.

hep-ph↗
arXiv2001

Self-Interacting Scalar Dark Matter and Higgs Decay

Self-interacting dark matter has been suggested in order to overcome the difficulties of the Cold Dark Matter model on galactic scales. We argue that a scalar gauge singlet coupled to the Higgs boson, leading to an invisibly decaying Higgs, is an interesting candidate for this self-interacting dark matter particle.

astro-ph↗
arXiv2000

Searching for Anomalous Higgs Couplings in Peripheral Heavy Ion Collisions at the LHC

We investigate the sensitivity of the heavy ion mode of the LHC to anomalous Higgs boson couplings to photons, H-photon-photon, through the analysis of the processes photon photon to b anti-b and photon photon to photon photon in peripheral heavy ion collisions. We suggest cuts to improve the signal over background ratio and determine the capability of LHC to impose bounds on anomalous couplings by searching for a Higgs boson signal in these modes.

hep-ph↗
arXiv2000

Critical coupling for chiral symmetry breaking in QCD motivated models

We determine the critical coupling constant above which dynamical chiral symmetry breaking occurs in a class of QCD motivated models where the gluon propagator has an enhanced infrared behavior. Using methods of bifurcation theory we find that the critical value of the coupling constant is always smaller than the one obtained for QCD.

hep-ph↗
arXiv2000

Self-interacting Dark Matter and Invisibly Decaying Higgs

Self-interacting dark matter has been suggested in order to overcome the difficulties of the Cold Dark Matter model on galactic scales. We argue that a scalar gauge singlet coupled to the Higgs boson, which could lead to an invisibly decaying Higgs, is an interesting candidate for this self-interacting dark matter particle. We also present estimates on the abundance of these particles today as well as consequences to non-Newtonian forces.

astro-ph↗
arXiv1998

Three Jet Events and New Strong Couplings at LEP and NLC

We study the effects of new dimension--6 operators, resulting from a general $SU(3)_C \otimes SU(2)_L \otimes U(1)_Y$ invariant effective Lagrangian, on three jet production at LEP and at the Next Linear Collider. Contributions to the total event rate and to some event shape variables are analysed in order to establish bounds on these operators.

hep-ph↗
arXiv1998

QCD Sum Rules Calculation of Heavy $Λ$ Semileptonic Decay

We set up sum rules for heavy lambda decays in a full QCD calculation which in the heavy quark mass limit incorporates the symmetries of heavy quark effective theory. For the semileptonic $\La_c$ decay we obtain a reasonable agreement with experiment. For the $\La_b$ semileptonic decay we find at the zero recoil point a violation of the heavy quark symmetry of about 20%.

hep-ph↗
arXiv1998

Testing Anomalous Higgs Couplings in Triple Photon Production at the Tevatron Collider

We derive bounds on Higgs and gauge--boson anomalous interactions using the CDF data for the process $p \bar{p} \to γγγ+ X$. We use a linearly realized $SU_L(2) \times U_Y(1)$ invariant effective Lagrangian to describe the bosonic sector of the Standard Model, keeping the fermionic couplings unchanged. All dimension--six operators that lead to anomalous Higgs interactions involving $γ$ and $Z$ are considered. We also show the sensitivity that can be achieved for these couplings at Fermilab Tevatron upgrades.

hep-ph↗
arXiv1997

Anomalous Higgs Couplings in Triple Gauge Boson Production at the NLC

We present the sensitivity limits on the coefficients of a dimension-6 effective operators that parametrizes the possible effects of new physics beyond the Standard Model. Our results are based on the study of the processes $e^+ e^- \to W^+ W^- γ$, $Z Zγ$, and $Zγγ$ at NLC energies. In our calculations, we include all the anomalous interactions involving vector and Higgs bosons, and take into account the Standard Model irreducible background. We analyse the impact of these new interactions on the total cross section and on some kinematical distributions of the final state particles.

hep-ph↗
arXiv1997

Anomalous Couplings in e^+ e^- --> W^+ W^- gamma at LEP2 and NLC

We present sensitivity limits on the coefficients of a dimension-6 effective Lagrangian that parametrizes the possible effects of new physics beyond the Standard Model. Our results are based on the study of the process $e^+ e^- \to W^+ W^- γ$ at LEP2 and NLC energies. In our calculations, we include all the new anomalous interactions, involving vector and Higgs bosons, and take into account the Standard Model irreducible background. We analyse the impact of these new interactions on the total cross section, including the effects of the initial electron and final W polarizations. We then focus on the operators that will not be constrained by the $e^+ e^- \to W^+ W^-$ process, obtaining limits based on the photon energy distribution.

hep-ph↗
arXiv1996

Probing Higgs Couplings in e^+ e^- \to γγγ

We investigate the existence of anomalous Higgs boson couplings, $Hγγ$ and $HZγ$, through the analysis of the process $e^+ e^- \to γγγ$ at LEP2 energies. We suggest some kinematical cuts to improve the signal to background ratio and determine the capability of LEP2 to impose bounds on those couplings by looking for a Higgs boson signal in this reaction.

hep-ph↗
arXiv1996

Anomalous Higgs Boson Contribution to e^+ e^- \to b \bbar γat LEP2

We study the effect of anomalous $Hγγ$ and $HZγ$ couplings, described by a general effective Lagrangian, on the process $e^+ e^- \to b \bar{b} γ$ at LEP2 energies. We include the relevant irreducible standard model background to this process, and from the photon energy spectrum, we determine the reach of LEP2 to unravel the anomalous couplings by analyzing the significance of the signal for Higgs boson with mass up to $150$ GeV.

hep-ph↗
arXiv1995

Can $Ω^- \to Ξ^- γ$ be sensitive to new physics beyond the Standard Model ?

We investigate the impact of new physics beyond the Standard Model to the $s \rightarrow d γ$ process, which is responsible for the short-distance contribution to the radiative decay $\Otogamma$. We study three representative extensions of the Standard Model, namely a one-family technicolor model, a two Higgs doublet model and a model containing scalar leptoquarks. When constraints arising from the observed $b \to s γ$ transition and the upper limit on $D^0 - \bar{D}^0$ mixing are taken into account, we find no significant contributions of new physics to the $s \to d γ$ process.

hep-ph↗
arXiv1995

LHC Analysis of the Strongly Interacting $WW$ System: Gold-Plated Modes

We study the gold-plated purely leptonic signal and background rates at the LHC for the $ZZ,$ $W^{+}W^-,$ $W^\pm Z$ and $W^\pm W^\pm$ final states associated with strongly interacting electroweak symmetry breaking. We work at an energy of $\sqrt s = 14$ TeV, and develop a combination of back-to-back leptonic, central-jet-vetoing and forwaring cuts that suppresses the Standard-Model backgrounds. We find that the LHC with an annual luminosity of 100 fb$^{-1}$ will achieve a reasonably good sensitivity to the physics of strongly interacting electroweak symmetry breaking.

hep-ph↗