HEP Phenomenology·hep-ph
42 papers—30 primary·12 cross-listed·reconstructed*
I present high-precision results for top quark production at hadron collider energies. Total and differential cross sections are calculated through aNLO for top-antitop pair production and through aNNLO for single-top production. Top production in association with a charged Higgs boson and via anomalous couplings is also briefly discussed.
In this presentation, we review the general features of integrand-reduction techniques, with a particular focus on their generalization beyond one loop. We start with a brief discussion of the one-loop scenario, a case in which integrand-reduction algorithms are well established and played over the past decade an important role in the development of automated tools for the theoretical evaluation of physical observables. The generalization of integrand-reduction techniques to all loops has been the subject of several efforts in the recent past, thus providing a better understanding of the universal properties of scattering amplitudes. The ultimate goal of these studies is the development of efficient alternative computational techniques for the evaluation of Feynman integrals beyond one loop.
J.A. Aguilar-Saavedra🇪🇸 · J.H. Collins🇺🇸 · S. Lombardo🇺🇸
We show that the relatively small but coincident excesses observed around 2 TeV in the ATLAS Run 1 and Run 2 hadronic diboson searches --- when a cut on the number of tracks in the fat jets is not applied --- and the null results of all remaining high-mass diboson searches are compatible with the decay of a triboson resonance into plus an extra particle . These decays can take place via new neutral () or charged () particles, namely , with , or , with . An obvious candidate for such intermediate particle is a neutral one , given a excess found at 650 GeV by the CMS Collaboration in searches for intermediate mass diboson resonances decaying to , with . We discuss discovery strategies for triboson resonances with small modifications of existing hadronic searches.
Sujeet Akula🇦🇺 · Csaba Balázs🇦🇺 · Graham A. White🇦🇺
We present semi-analytic techniques for finding bubble wall profiles during first order phase transitions with multiple scalar fields. Our method involves reducing the problem to an equation with a single field, finding an analytic solution and perturbing around it. The perturbations can be written in a semi-analytic form. We argue that our technique lacks convergence problems and demonstrate the speed of convergence on an example potential.
B. Blok🇮🇱 · M. Strikman🇺🇸
We calculate the rate of double open charm production in the forward kinematics studied recently in the LHCb experiment. We find that the mean field approximation for the double parton GPD (Generalized parton distributions), which neglects parton - parton correlations, underestimates the rate by a factor of two. The enhancement due to the perturbative QCD correlation \12 mechanism which explains the rate of double parton interactions at the central rapidities is found to explain 60 80 \% of the discrepancy. We argue that the nonperturbative fluctuations leading to non-factorized (correlated) contributions to the initial conditions for the DGLAP collinear evolution of the double parton GPD play an important role in this kinematics. Combined, the two correlation mechanisms provide a good description of the rate of double charm production reported by the LHCb. We also give predictions for the variation of the \effs (i.e. the ratio of double and square of single inclusive rates) in the discussed kinematics as a function of . The account for two correlation mechanisms strongly reduces sensitivity of the results to the starting point of the QCD evolution.
Benjamin Fuks🇫🇷 · Dong Woo Kang🇰🇷 · Seong Chan Park🇰🇷 · Min-Seok Seo🇰🇷
We study the jet activity that accompanies the production by gluon fusion of a new physics scalar particle decaying into photons at the LHC. In the considered scenarios, both the production and decay mechanisms are governed by loop-induced interactions involving a heavy colored state. We show that the presence of large new physics contributions to the inclusive diphoton invariant-mass spectrum always implies a significant production rate of non-standard diphoton events containing extra hard jets. We investigate the existence of possible handles that could provide a way to obtain information on the underlying physics behind the scalar resonance, and this in a wide mass window.
Naoyuki Haba🇯🇵 · Hiroyuki Ishida🇯🇵 · Nobuchika Okada🇺🇸 · Yuya Yamaguchi🇯🇵
We suggest a scalar singlet extension of the standard model, in which the multiple-point principle (MPP) condition of a vanishing Higgs potential at the Planck scale is realized. Although there have been lots of attempts to realize the MPP at the Planck scale, the realization with keeping naturalness is quite difficult. Our model can easily achieve the MPP at the Planck scale without large Higgs mass corrections. It is worth noting that the electroweak symmetry can be radiatively broken in our model. In the naturalness point of view, the singlet scalar mass should be of or less. We also consider right-handed neutrino extension of the model for neutrino mass generation. The model does not affect the MPP scenario, and might keep the naturalness with the new particle mass scale beyond TeV, thanks to accidental cancellation of Higgs mass corrections.
Jochen Bartels🇩🇪 · Eugene Levin🇨🇱 · Marat Siddikov🇨🇱
In this paper we study the high energy behaviour of Electroweak Standard Model for a nonzero Weinberg angle . We evaluate the spectrum of the electroweak pomeron and demonstrate that the leading intercept is given by and does not depend on the mixing angle . Due to its very small numerical value, we conclude that the high energy behaviour of electroweak theory cannot be discussed without including the QCD Pomeron which, at sufficiently large energies, will dominate.
We propose an explanation of the LHC data excess resonance of 750 GeV in the diphoton distribution using D-brane models, with gauged baryon number, which accommodate the Standard Model together with vector like exotics. We identify the 750 GeV scalar as either the sneutrino () or as an axion. Using a bottom-up approch, is produced via gluon fusion when scalar (supersymmetric) partners of vector like quarks and leptons are generated by demanding that the corresponding intersections respect N=1 supersymmetry. When we generate the value of at 750 GeV, by varying the complex structure of the torus, the string scale is limited to be in the range GeV. Also, generating the Higgs scalars by imposing N=1 supersymmetry on intersections fixes naturally, to zero, the coupling of the axion to SU(2) gauge bosons and in photon-photon fusion also decouples its coupling from of color SU(3) by simultaneously generating the superpartners of , , , quarks and leptons.
Yusuke Shimizu🇯🇵 · Yoshiyuki Tatsuta🇯🇵
We discuss the neutrino flavor structures in the Occam's razor approach for the Dirac neutrino mass matrices. We assume that the charged lepton mass matrix takes a diagonal base, while the right-handed Majorana neutrino mass matrix is also diagonal and we consider nine patterns of the four zero textures for the Dirac neutrinos mass matrices. We numerically analyze the left-handed Majorana neutrino mass matrices for nine patterns of the Dirac neutrino mass matrices and we found two interesting patterns where both normal and inverted neutrino mass hierarchies can be realized. We also found if the neutrino mass is normal hierarchy, this scenario will be likely to be excluded by the measurements of the Dirac CP violating phase in the T2K and NOA neutrino experiments, for instance. On the other hand, if the neutrino mass is inverted hierarchy, this scenario will be also likely to be excluded by the measurements of neutrinoless double beta decay experiments, e.g., KamLAND-Zen experiment.
The exclusive processes are considered, where a point-like source of heavy quark-antiquark pairs , e.g. their electromagnetic current, produces a pair consisting of a heavy quarkoniumlike exotic meson (tetraquark) or baryon (pentaquark) and a light meson or an antibaryon. For a sufficiently large mass of the heavy quark there is a range of the energy above the threshold, where and still the energy is large compared to the strong interaction scale, . It is shown that in this energy range, where the heavy quarks are nonrelelativistic, a specific `intermediate asymptotic' behavior sets in determined by the number of the pairs of constituent quarks, with the rate scaling as .
The neutral-kaon system constitutes a fantastic and unique laboratory for the study of CPT symmetry and the basic principles of quantum mechanics, and a -factory represents a unique opportunity to push forward these studies. The experimental results show no deviation from the expectations of quantum mechanics and CPT symmetry, while the extreme precision of the measure- ments, in some cases, reaches the interesting Planck-scale region. At present the KLOE-2 experiment is collecting data with an upgraded detector with the aim of significantly improving these kinds of experimental tests.
Mohammad Abdullah🇺🇸 · Jonathan L. Feng🇺🇸 · Sho Iwamoto🇮🇱 · Benjamin Lillard🇺🇸
MSSM4G models, in which the minimal supersymmetric standard model is extended to include vector-like copies of standard model particles, are promising possibilities for weak-scale supersymmetry. In particular, two models, called QUE and QDEE, realize the major virtues of supersymmetry (naturalness consistent with the 125 GeV Higgs boson, gauge coupling unification, and thermal relic neutralino dark matter) without the need for fine-tuned relations between particle masses. We determine the implications of these models for dark matter and collider searches. The QUE and QDEE models revive the possibility of heavy Bino dark matter with mass in the range 300-700 GeV, which is not usually considered. Dark matter direct detection cross sections are typically below current limits, but are naturally expected above the neutrino floor and may be seen at next-generation experiments. Indirect detection prospects are bright at the Cherenkov Telescope Array, provided the 4th-generation leptons have mass above 350 GeV or decay to taus. In a completely complementary way, discovery prospects at the LHC are dim if the 4th-generation leptons are heavy or decay to taus, but are bright for 4th-generation leptons with masses below 350 GeV that decay either to electrons or to muons. We conclude that the combined set of direct detection, CTA, and LHC experiments will discover or exclude these MSSM4G models in the coming few years, assuming the Milky Way has an Einasto dark matter profile.
Wei-Jun Deng🇨🇳 · Hui Liu🇨🇳 · Long-Cheng Gui🇨🇳 · Xian-Hui Zhong🇨🇳
The charmonium spectrum is calculated with two nonrelativistic quark models, the linear potential model and the screened potential model. Using the obtained wavefunctions, we evaluate the electromagnetic transitions of charmonium states up to multiplet. The higher multipole contributions are included by a multipole expansion of the electromagnetic interactions. Our results are in reasonable agreement with the measurements. As conventional charmonium states, the radiative decay properties of the newly observed charmonium-like states, such as , , , are discussed. The as , its radiative decay properties well agree with the observations. From the radiative decay properties of , one can not exclude it as a dominant state. We also give discussions of possibly observing the missing charmonium states in radiative transitions, which might provide some useful references to look for them in forthcoming experiments. The higher multipole contributions to the electromagnetic transitions are analyzed as well. It is found that the higher contribution from the magnetic part could give notable corrections to some E1 dominant processes by interfering with the E1 amplitudes. Our predictions for the normalized magnetic quadrupole amplitudes of the processes are in good agreement with the recent CLEO measurements.
R. Nevzorov🇦🇺 · A. W. Thomas🇦🇺
In the E6 inspired composite Higgs model (E6CHM) the strongly interacting sector possesses an SU(6)\times U(1)_B\times U(1)_L global symmetry. Near scale f\gtrsim 10 TeV the SU(6) symmetry is broken down to its SU(5) subgroup, that involves the standard model (SM) gauge group. This breakdown of SU(6) leads to a set of pseudo--Nambu--Goldstone bosons (pNGBs) including a SM--like Higgs and a SM singlet pseudoscalar A. Because of the interactions between A and exotic fermions, which ensure the approximate unification of the SM gauge couplings and anomaly cancellation in this model, the couplings of the pseudoscalar A to gauge bosons get induced. As a result, the SM singlet pNGB state A with mass around 750 GeV may give rise to sufficiently large cross section of pp\to \gamma\gamma that can be identified with the recently observed diphoton excess.
Shu Ebihara🇯🇵 · Kenji Fukushima🇯🇵 · Kazuya Mameda🇯🇵
We discuss the importance of boundary effects on fermionic matter in a rotating frame. By explicit calculations at zero temperature we show that the scalar condensate of fermion and anti-fermion cannot be modified by the rotation once the boundary condition is properly implemented. The situation is qualitatively changed at finite temperature and/or in the presence of a sufficiently strong magnetic field that supersedes the boundary effects. Therefore, to establish an interpretation of the rotation as an effective chemical potential, it is crucial to consider further environmental effects such as the finite temperature and magnetic field.
Kingman Cheung🇹🇼 · P. Ko🇰🇷 · Jae Sik Lee🇰🇷 · Jubin Park🇰🇷 · Po-Yan Tseng🇹🇼
Searches for diphoton resonance have been shown to be very useful in discovering new heavy spin-0 or spin-2 particles. Supposing that a new heavy particle shows up in the diphoton channel and it points to a spin-0 boson, it can be allowed to have a small mixing with the observed 125 GeV Higgs-like boson. We borrow the example of the 750 GeV particles hinted with 3.2 fb data at the end of 2015 (though it did not appear in the 2016 data) to perform an analysis of "double Higgcision". In this work, we perform a complete Higgs-signal strength analysis in the Higgs-portal type framework, using all the existing 125 GeV Higgs boson data as well as the diphoton signal strength of the 750 GeV scalar boson. The best fit prefers a very tiny mixing between two scalar bosons, which has to be accommodated in models for the 750 GeV scalar boson.
M. De Sanctis🇨🇴 · J. Ferretti🇮🇹 · R. Magaña Vsevolodovna🇮🇹 · P. Saracco🇮🇹 · E. Santopinto🇮🇹
We describe the relativistic interacting quark-diquark model formalism and its application to the calculation of strange and nonstrange baryon spectra. The results are compared to the existing experimental data. We also discuss the application of the model to the calculation of other baryon observables, like baryon magnetic moments, open-flavor strong decays and baryon masses with self-energy corrections.
H. García-Tecocoatzi🇮🇹 · R. Bijker🇲🇽 · J. Ferretti🇮🇹 · G. Galatà🇲🇽 · E. Santopinto🇮🇹
In this contribution, we discuss the results of a QM calculation of the open-flavor strong decays of **** light nucleon resonances. These are the results of a recent calculation, where we used a modified model for the amplitudes and the U(7) algebraic model and the Hypercentral Quark Model to predict the baryon spectrum. The decay amplitudes are compared with the existing experimental data.
M.K. Volkov🇷🇺 · A.A. Pivovarov🇷🇺
The processes and are calculated in the framework of the extended Nambu-Jona-Lasinio model. The intermediate vector mesons and their first radially-excited states are taken into account. The obtained results are in satisfactory agreement with the experimental data. The predictions for the cross sections of the reactions , and were made.
Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Jurgen G. Korner🇩🇪 · Valery E. Lyubovitskij🇩🇪
We present a study of the isospin-violating one-pion strong decays of single heavy tetraquarks , , and with spin-parity . We assume that the tetraquarks have the configuration of a color diquark and a antidiquark. Three mechanisms of isospin violation can contribute to the decay rate: (1) mixing of the and tetraquark currents, (2) an explicit quark mass difference in the quark diagrams describing the corresponding decay transitions and (3) mixing in the final state. Our main results are: (1) It is quite likely that the investigated tetraquark states are isosinglet states with a small admixture of an isotriplet component; (2) The first isospin-breaking mechanism affects the decay rater more significantly than the others; (3) Our calculations contain a size parameter , characterizing the distribution of the quarks in the tetraquark state . Absolute decay rates depend very much on the choice of , varied from 1 to 2 GeV, reflecting the compactness of the multiquark system.
Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Jurgen G. Korner🇩🇪 · Sergey Kovalenko🇨🇱 · Valery E. Lyubovitskij🇩🇪
We present results for the isotriplet and isosinglet tensor form factors of the nucleon in the relativistic confined quark model. The model allows us to calculate not only their normalizations at and the related tensor charges, but also the full -dependence. Our results are compared to existing data and predictions of other theoretical approaches. We stress the importance of these form factors for the phenomenology of physics beyond the Standard Model.
Ning Chen🇨🇳 · Zhaofeng Kang🇰🇷 · Jinmian Li🇦🇺
The extended Higgs sector, such as by a second Higgs doublet of type-II, provides portals to dark sector which contains missing particles at the LHC, e.g., dark matter (DM) particles. In this paper, working in the simplified model and taking into consideration the wide decay width effect of the mediator, we analyze the characteristic signatures of mono-+MET and 2+MET at the LHC. The latter signature was believed to be ineffective, while we found that, with the aid of razor shape analysis, it should be as important as the mono- signature. In the region of relatively low mediator mass (below a few hundred GeV), by requiring the signal to background ratio greater than a few percent, the 2-tagged razor analysis has comparable sensitivity to the mono- search; it is even better for mediator lighter than GeV.
V. B. Bezerra🇧🇷 · G. L. Klimchitskaya🇷🇺 · V. M. Mostepanenko🇷🇺 · C. Romero🇧🇷
We propose an experiment for measuring the effective Casimir pressure between two parallel SiC plates with aligned nuclear spins. The prospective constraints on an axion-neutron coupling constant for both hadronic and GUT axions are calculated using the process of one-axion exchange. For this purpose, a general expression for the additional pressure arising between two polarized plates due to the exchange of one axion between their constituent fermions is derived. We demonstrate that only the polarization component perpendicular to the plates contribute to the pressure. The obtained pressure can be both repulsive and attractive depending on whether the polarizations of both plates are unidirectional or directed in opposite directions. It is shown that although the constraints on an axion-electron coupling obtained in the case of magnetized plates are not competitive, the constraints on an axion-neutron coupling found for plates with polarized nuclear spins are of the same order of magnitude of those obtained previously for the GUT axions alone using the process of two-axion exchange. The proposed experiment allows also to strengthen the presently known constraints on the axion-neutron coupling constants of GUT axions by using both processes of one- and two-axion exchange.
S. Momeni · R. Khosravi
The decays occur by the electroweak penguin and box diagrams which can be performed through the flavor changing neutral current (FCNC). We calculate the form factors of the FCNC transitions in the light--cone sum rules approach, up to twist--4 distribution amplitudes of the axial vector meson . Forward--backward asymmetry, as well as branching ratios of , and decays are considered. A comparison is also made between our results and the predictions of other methods.
Byung-Geel Yu🇰🇷 · Yongseok Oh🇰🇷 · Kook-Jin Kong🇰🇷
Photoproduction of vector mesons off nucleon is investigated within the Regge framework where the electromagnetic vertex of fully takes into account the magnetic dipole and electric quadrupole moments of spin-1 vector meson. The -channel , and meson exchanges are considered for the analysis of the production mechanism. The experimentally observed rapid decrease of the cross sections for the reaction beyond the resonance region is well reproduced by the dominance of the exchange of -meson trajectory. The role of the scalar -meson trajectory is found to be minor in both and reactions. The cross sections for the reaction are predicted to be about twice those of the reaction. The role of the electromagnetic multipoles and the proton anomalous magnetic moment is studied through the total and differential cross sections and spin/parity asymmetries. We suggest the measurement of the photon polarization asymmetry as a tool for identifying the role of the magnetic dipole and electric quadrupole moments of the vector meson.
Mikulas Gintner🇸🇰 · Josef Juran🇨🇿
In this paper, we investigate how the LHC data limit the Higgs-related couplings in the effective description of a strongly interacting extension of the Standard model. The Higgs boson is introduced as a scalar composite state and it is followed in the mass hierarchy by an triplet of vector composites. The limits are calculated from the constraints obtained in the recent ATLAS+CMS combined analysis of the data from 2011 and 2012. We find that the data prefer the scenario where the Higgs couplings to the electroweak gauge bosons differ from its couplings to the vector triplet. We also investigate the unitarity limits of the studied effective model for the experimentally preferred values of the Higgs couplings. We find from the scattering amplitudes that for the vector resonance masses between one and two TeV significant portions of the experimentally allowed regions are well below the unitarity limit. We also evaluate how the existing ATLAS and CMS Run-2 data restrict our model with the upper bounds on the resonance production cross section times its branching ratio for various decay channels. The masses in the range are not excluded in parts or even full parameter space of our theory.
Zhiguang Xiao🇨🇳 · Zhi-Yong Zhou🇨🇳
We study the well-known Friedrichs model, in which a discrete state is coupled to a continuum state. By examining the pole behaviors of the Friedrichs model in a specific form factor thoroughly, we find that, in general, when the bare discrete state is below the threshold of the continuum state, there should also be a virtual-state pole accompanying the bound-state pole originating from the bare discrete state as the coupling is turned on. There are also other second-sheet poles originating from the singularities of the form factor. We give a general argument for the existence of these two kinds of states. As the coupling is increased to a certain value, the second-sheet poles may merge and become higher-order poles. We then discuss the completeness relations incorporating bound states, virtual states, and resonant states corresponding to higher-order poles.
Ultrarelativistic heavy ion collisions produce a quark-gluon matter which lies in the future light cone originating from given points on the plane of the Minkowski spacetime manifold. We show that in a weak coupling regime the Minkowski vacuum of massless fields presents itself in the "Little Bang" region as a thermal state of low particles, in close analogy to the Unruh effect for uniformly accelerated observers which are causally restricted to a Rindler wedge. It can shed some light on the mechanisms of early time thermalization in ultrarelativistic heavy ion collisions.
Paola Arias🇨🇱 · Ariel Arza and🇨🇱 · Jorge Gamboa🇨🇱
The effects of an external time-dependent magnetic field in the conversion probability of photon-to-axion-like particles are studied. Our findings show that for a certain time regime, the amplitude of the produced axion-like field can be enlarged with respect to the static case, thus, enhancing the probability of conversion.
A recent study, making use of the number of horizontal branch stars observed in infrared photometric surveys and kinematic measurements of M-giant stars from the BRAVA survey, combined with N-body simulations of stellar populations, has presented a new determination of the dark matter mass within the bulge-bar region of the Milky Way. That study constrains the total mass within the kpc volume of the bulge-bar region to be (, of which 9-30% is made up of dark matter. Here, we use this result to constrain the the Milky Way's dark matter density profile, and discuss the implications for indirect dark matter searches. Although uncertainties remain significant, these results favor dark matter distributions with a cusped density profile. For example, for a scale radius of 20 kpc and a local dark matter density of 0.4 GeV/cm, density profiles with an inner slope of 0.69 to 1.40 are favored, approximately centered around the standard NFW value. In contrast, profiles with large flat-density cores are disfavored by this information.
Lukas Hergt (ETHZ)🇨🇭 · Adam Amara (ETHZ)🇨🇭 · Robert Brandenberger (McGill U./ETHZ)🇨🇦 · Tomasz Kacprzak (ETHZ)🇨🇭 · Alexandre Refregier (ETHZ)🇨🇭
We use wavelet and curvelet transforms to extract signals of cosmic strings from cosmic microwave background (CMB) temperature anisotropy maps, and to study the limits on the cosmic string tension which various ongoing CMB temperature anisotropy experiments will be able to achieve. We construct sky maps with size and angular resolution corresponding to various experiments. These maps contain the signals of a scaling solution of long string segments with a given string tension , the contribution of the dominant Gaussian primordial cosmological fluctuations, and pixel by pixel white noise with an amplitude corresponding to the instrumental noise of the various experiments. In the case that we include white noise, we find that the curvelets are more powerful than wavelets. For maps with Planck specification, we obtain bounds on the string tension comparable to what was obtained by the Planck collaboration. Experiments with better angular resolution such as the South Pole Telescope third generation (SPT-3G) survey will be able to yield stronger limits. For maps with a specification of SPT-3G we find that string signals will be visible down to a string tension of .
The redshift drift of objects moving in the Hubble flow has been proposed as a powerful model-independent probe of the underlying cosmology. A measurement of the first and second order redshift derivatives appears to be well within the reach of upcoming surveys using ELT-HIRES and the SKA Phase 2 array. Here we show that an unambiguous prediction of the R_h=ct cosmology is zero drift at all redshifts, contrasting sharply with all other models in which the expansion rate is variable. For example, multi-year monitoring of sources at redshift z=5 with the ELT-HIRES is expected to show a velocity shift Delta v = -15 cm/s/yr due to the redshift drift in Planck LCDM, while Delta v=0 cm/s/yr in R_h=ct. With an anticipated ELT-HIRES measurement error of +/-5 cm/s/yr after 5 years, these upcoming redshift drift measurements might therefore be able to differentiate between R_h=ct and Planck LCDM at ~3 sigma, assuming that any possible source evolution is well understood. Such a result would provide the strongest evidence yet in favour of the R_h=ct cosmology. With a 20-year baseline, these observations could favor one of these models over the other at better than 5 sigma.
Thomas A. Ryttov🇩🇰 · Robert Shrock🇺🇸
We present a scheme-independent calculation of the infrared value of the anomalous dimension of the fermion bilinear, in an SU(3) gauge theory as a function of the number of fermions, , via a series expansion in powers of , where , to order . We perform an extrapolation to obtain the first determination of the exact from continuum field theory. The results are compared with calculations of the -loop values of this anomalous dimension from series in powers of the coupling and from lattice measurements.
Amruta Mishra🇮🇳 · S.P. Misra🇮🇳
We compute the in-medium partial decay widths of the bottomonium states to open bottom mesons () using a field theoretical model for composite hadrons with quark constituents. These decay widths are calculated by using the explicit constructions for the bottomonium states and the open bottom mesons ( and ), and, the quark antiquark pair creation term of the free Dirac Hamiltonian written in terms of the constituent quark field operators. These decay widths in the hadronic medium are calculated as arising from the mass modifications of the bottomonium states and the and mesons, obtained in a chiral effective model. The decay amplitude in the present model is multiplied with a strength parameter for the light quark pair creation, which is fitted from the observed vacuum partial decay width of the bottomonium state, to . The effects of the isospin asymmetry, the strangeness fraction of the hadronic matter on the decay widths, arising due to the mass modifications due to these effects, have also been studied. There is observed to be appreciable effects from density, and the effects from isospin asymmetry on the parital decay widths of are observed to be quite pronounced at high densities. These effects should show up in the asymmetric heavy ion collisions in Compressed baryonic matter (CBM) experiments planned at the future facility at FAIR. The study of the states will, however, require access to energies higher than the energy regime planned at the CBM experiment. The density effects on the decay widths of the bottomonium states should show up in the production of these states, as well as, in dilepton spectra at the Super Proton Synchrotron (SPS) energies.
We consider a broad class of inflationary models of two unconstrained chiral superfields, the stabilizer and the inflaton , which can describe inflationary models with nearly arbitrary potentials. These models include, in particular, the recently introduced theories of cosmological attractors, which provide an excellent fit to the latest Planck data. We show that by adding to the superpotential of the fields and a small term depending on a nilpotent chiral superfield one can break SUSY and introduce a small cosmological constant without affecting main predictions of the original inflationary scenario.
How likely is it that there are particles in a vector-like pair of representations in low-energy spectrum, when neither symmetry nor anomaly consideration motivates their presence? We address this question in the context of supersymmetric and geometric phase compactification of F-theory and Heterotic dual. Quantisation of the number of generations (or net chiralities in more general term) is also discussed along the way. Self-dual nature of the fourth cohomology of Calabi--Yau fourfolds is essential for the latter issue, while we employ Brill--Noether theory to set upper bounds on the number of vector-like pairs of chiral multiplets in the SU(5) 5+5bar representations. For typical topological choices of geometry for F-theory compactification for SU(5) unification, the range of for perturbative unification is not in immediate conflict with what is already understood about F-theory compactification at this moment.
We present an overview of the foundation, evolution, contributions and future prospects of the TEXONO Collaboration and its research programs on neutrino physics and dark matter searches at the Kuo-Sheng Reactor Neutrino Laboratory in Taiwan and, as a founding partner of the CDEX program, at the China Jinping Underground Laboratory in China.
G. Salesi🇮🇹 · M. Greselin🇮🇹 · L. Deleidi🇮🇹 · R.A. Peruzza🇮🇹
We extend a recent approach to Deformed Special Relativity based on deformed dispersion laws, entailing modified Lorentz transformations and, at the same time, noncommutative geometry and intrinsically discrete spacetime. In so doing we obtain the explicit form of the modified Lorentz transformations for a special class of modified momentum-energy relations often found in literature and arising from elementary particle physics. Actually, our theory looks as a very simple and natural extension of special relativity to include a momentum cut-off at the Planck scale. In particular, the new Lorentz transformations do imply that for high boost speed () the deformed Lorentz factor does not diverge as in ordinary relativity, but results to be upperly bounded by a large finite value of the order of the ratio between the Planck mass and the particle mass. We also predict that a generic boost leaves unchanged Planck energy and momentum, which result invariant with respect to any reference frame.
Under the existence of chiral non-Gaussian sources during inflation, the trispectrum of primordial curvature perturbations can break parity. We examine signatures of the induced trispectrum of the cosmic microwave background (CMB) anisotropies. It is confirmed via a harmonic-space analysis that, as a consequence of parity violation, such a CMB trispectrum has nonvanishing signal in the domain, which is prohibited in the concordance cosmology. When the curvature trispectrum is parametrized with Legendre polynomials, the CMB signal due to the Legendre dipolar term is enhanced at the squeezed configurations in space, yielding a high signal-to-noise ratio. A Fisher matrix computation results in a minimum detectable size of the dipolar coefficient in a cosmic-variance-limited-level temperature survey as . In an inflationary model where the inflaton field couples to the gauge field via an interaction, the curvature trispectrum contains such a parity-odd dipolar term. We find that, in this model, the CMB trispectrum yields a high signal-to-noise ratio compared with the CMB power spectrum or bispectrum. Therefore, the signal could be a promising observable of cosmological parity violation.
Massive particles with self interactions of the order of 0.2 barn/GeV are intriguing Dark Matter candidates from an astrophysical point of view. Current and past experiments for direct detection of massive Dark Matter particles are focusing to relatively low cross sections with ordinary matter, however they cannot rule out very large cross sections, barn/GeV, due to atmosphere and material shielding. Cosmology places a strong indirect limit for the presence of large interactions among Dark Matter and baryons in the Universe, however such a limit cannot rule out the existence of a small sub-dominant component of Dark Matter with non negligible interactions with ordinary matter in our galactic halo. Here, the possibility of the existence of bound states with ordinary matter, for a similar Dark Matter candidate with not negligible interactions, is considered. The existence of bound states, with binding energy larger than 1 meV, would offer the possibility to test in laboratory capture cross sections of the order of a barn (or larger). The signature of the detection for a mass increasing of cryogenic samples, due to the possible particle accumulation, would allow the investigation of these Dark Matter candidates with mass up to the GUT scale. A proof of concept for a possible detection set-up and the evaluation of some noise sources are described.
David Valenzuela🇨🇱 · Saúl Hernández-Ortiz🇲🇽 · Marcelo Loewe🇿🇦 · Alfredo Raya🇲🇽
We explore the problem of atomic collapse in graphene by monopole impurities, both electric and magnetic, within the context of supersymmetric quantum mechanics. For electric impurities, upon factorizing the radial Dirac Hamiltonian and identifying the supercharges, existence of a critical charge that makes the ground state {\em fall-into-the-center} translates into lost of hermicity for the corresponding Hamiltonian and hence lost of unitarity of the theory. For the problem of magnetic monopole impurities, preservation of unitarity for all values of the parameters of the corresponding potential translates into the absence of atomic collapse in this case.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.