Thu·Dec 15, 2016Thursday·December 15, 2016

1. 01*

   Yukawa Sector of Minimal SO(10) Unification

   K.S. Babu🇺🇸 · Borut Bajc🇸🇮 · Shaikh Saad🇺🇸

   We show that in SO(10) models, a Yukawa sector consisting of a real $10_H$, a real $120_H$ and a complex $126_H$ of Higgs fields can provide a realistic fit to all fermion masses and mixings, including the neutrino sector. Although the group theory of SO(10) demands that the $10_H$ and $120_H$ be real, most constructions complexify these fields and impose symmetries exterior to SO(10) to achieve predictivity. The proposed new framework with real $10_H$ and real $120_H$ relies only on SO(10) gauge symmetry, and yet has a limited number of Yukawa parameters. Our analysis shows that while there are restrictions on the observables, a good fit to the entire fermion spectrum can be realized. Unification of gauge couplings is achieved with an intermediate scale Pati-Salam gauge symmetry. Proton decay branching ratios are calculable, with the leading decay modes being $p\to \overline{\nu }{\pi }^{+}$ and $p\to e^{+}{\pi }^0$.

   hep-phJHEP(2017)·109 citations
2. 02*

   Helicity Amplitudes for massive gravitinos in N=1 Supergravity

   J. Lorenzo Diaz-Cruz🇲🇽 · Bryan O. Larios🇲🇽

   We develop the formal tools needed to construct helicity amplitudes for massive gravitino in N=1 SUGRA. We start by considering the helicity states for massive spin-3/2 particles, which involves the solutions of Rarita-Schwinger equation. These solutions are written in terms of the helicity bra-ket notation and are used then to derive the interactions of gravitino with matter and gauge supermultiplets within N=1 Supergravity. The corresponding interactions of goldstinos are discussed too, relying on the goldstino-gravitino equivalence theorem. Finally to appreciate the power of our methods we evaluate the decay width chi_0 -> \gamma G, as well as the cross sections for e^+ e- -> GG.

   hep-phJ.Phys.G(2018)·9 citations
3. 03*

   Direct photon production at next-to-next-to-leading order

   John M. Campbell🇺🇸 · R. Keith Ellis🇬🇧 · Ciaran Williams🇺🇸

   We present the first calculation of direct photon production at next-to-next-to leading order (NNLO) accuracy in QCD. For this process, although the final state cuts mandate only the presence of a single electroweak boson, the underlying kinematics resembles that of a generic vector boson plus jet topology. In order to regulate the infrared singularities present at this order we use the $N$-jettiness slicing procedure, applied for the first time to a final state that at Born level includes colored partons but no required jet. We compare our predictions to ATLAS 8 TeV data and find that the inclusion of the NNLO terms in the perturbative expansion, supplemented by electroweak corrections, provides an excellent description of the data with greatly reduced theoretical uncertainties.

   hep-phhep-exPRL(2017)·127 citations
4. 04*

   Origin of CP violation for leptogenesis in seesaw

   Pei-Hong Gu🇨🇳

   We reveal the origin of the CP violation required by the leptogenesis in variously popular seesaw models. Especially we clarify that in a pure type-I/III seesaw with two fermion singlets/triplets, a combined type-I+III seesaw with one fermion singlet and one fermion triplet, or a combined type-I/III+II seesaw with one fermion singlet/triplet and one Higgs triplet, the CP violation for the leptogenesis can exactly come from the imaginary part of the neutrino mass matrix in a special basis where the Yukawa couplings involving one fermion singlet/triplet are allowed to get rid of any CP phases. We also generalize our findings as a very good approximation when these seesaw scenarios are extended by more fermion singlets/triplets and Higgs triplets while the leptogenesis is realized by the decays of the lightest fermion singlet/triplet.

   hep-ph2 citations
5. 05*

   Full Colour for Loop Amplitudes in Yang-Mills Theory

   Alexander Ochirov🇬🇧 · Ben Page🇩🇪

   We present a general method to account for full colour dependence Yang-Mills amplitudes at loop level. The method fits most naturally into the framework of multi-loop integrand reduction and in a nutshell amounts to consistently retaining the colour structures of the unitarity cuts from which the integrand is gradually constructed. This technique has already been used in the recent calculation of the two-loop five-gluon amplitude in pure Yang-Mills theory with all positive helicities, arXiv:1507.08797. In this note, we give a careful exposition of the method and discuss its connection to loop-level Kleiss-Kuijf relations. We also explore its implications for cancellation of nontrivial symmetry factors at two loops. As an example of its generality, we show how it applies to the three-loop case in supersymmetric Yang-Mills case.

   hep-phhep-thJHEP(2017)·34 citations
6. 06*

   Non-coherent contributions in charge-exchange reactions and $\eta$--${\eta }^{\prime }$ mixing

   M. L. Nekrasov🇷🇺

   We analyse $K^{-}p\to (\eta ,{\eta }^{\prime },{\pi }^0)\Lambda$ on the basis of the fit of data in a wide region of energies, and ${\pi }^{-}p\to (\eta ,{\eta }^{\prime })n$ at the energies of GAMS-4$\pi$. We show that disagreements between the data and the predictions of Regge theory may be explained by the mode change of summation of intermediate contributions at increasing energy, from coherent to non-coherent. A method of experimental measurement of the non-coherent contributions is proposed. On the basis of available data on the charge-exchange reactions the $\eta$--${\eta }^{\prime }$ mixing is estimated.

   hep-phEPJA(2017)·1 citation
7. 07*

   Reheating and Leptogenesis after Pati-Salam F-term Subcritical Hybrid Inflation

   B. Charles Bryant🇺🇸 · Zijie Poh🇺🇸 · Stuart Raby🇺🇸

   In this paper, we extend the analysis of a Pati-Salam subcritical hybrid $F$-term inflation model, proposed by two of us, by studying the reheating and the baryogenesis (via leptogenesis) of the model. This SUSY GUT model is able to fit low energy electroweak precision data, LHC data, $b$-physics data, in addition to inflation observables such as the tensor-to-scalar ratio and the scalar spectral index. The reheating mechanism of this model is instant preheating due to the bosonic and fermionic broad parametric resonance, while the baryon-to-entropy ratio is obtained from the CP asymmetric right-handed (s)neutrinos decay. The phases in the neutrino Yukawa matrices are fixed by fitting to the low energy observables. With these phases, the heaviest right-handed (s)neutrinos decay to produce a lepton asymmetry with the correct sign, while the two lighter right-handed (s)neutrinos decay to produce the wrong sign. Consequently, the baryogenesis analysis is necessarily performed by including all three families of the right-handed (s)neutrinos.

   hep-ph8 citations
8. 08*

   R-parity as a residual gauge symmetry : probing a theory of cosmological dark matter

   Alexandre Alves🇧🇷 · Giorgio Arcadi🇩🇪 · P. V. Dong🇻🇳 · Laura Duarte🇧🇷 · Farinaldo S. Queiroz🇩🇪 · José W. F. Valle🇪🇸

   We present a non-supersymmetric scenario in which the R-parity symmetry $R_P=(-1{)}^{3(B-L)+2s}$ arises as a result of spontaneous gauge symmetry breaking, leading to a viable Dirac fermion WIMP dark matter candidate. Direct detection in nuclear recoil experiments probes dark matter masses around $2-5$ TeV for $M_{Z^{\prime }}\sim 3-4$ TeV consistent with searches at the LHC, while lepton flavor violation rates and flavor changing neutral currents in neutral meson systems lie within reach of upcoming experiments.

   hep-phastro-ph.HEhep-exhep-thPLB(2017)·65 citations
9. 09*

   Four-loop photon quark form factor and cusp anomalous dimension in the large-$N_c$ limit of QCD

   Johannes Henn🇩🇪 · Roman N. Lee🇷🇺 · Alexander V. Smirnov · Vladimir A. Smirnov · Matthias Steinhauser🇩🇪

   We compute the four-loop QCD corrections to the massless quark-anti-quark-photon form factor $F_q$ in the large-$N_c$ limit. From the pole part we extract analytic expressions for the corresponding cusp and collinear anomalous dimensions.

   hep-phJHEP(2017)·99 citations
10. 10*

    Volume dependence of baryon number cumulants and their ratios

    Gabor A. Almasi🇩🇪 · Robert D. Pisarski🇺🇸 · Vladimir V. Skokov🇺🇸

    We explore the influence of finite volume effects on baryon number fluctuations in a non-perturbative chiral model. In order to account for soft modes, we use the functional renormalization group in a finite volume, using a smooth regulator function in momentum space. We compare the results for a smooth regulator with those for a sharp (or Litim) regulator, and show that in a finite volume, the latter produces spurious artifacts. In a finite volume there are only apparent critical points, about which we compute the ratio of the fourth to the second order cumulant of quark number fluctuations. When the volume is sufficiently small the system has two apparent critical points; as the system size decreases, the location of the apparent critical point can move to higher temperature and lower chemical potential.

    hep-phPRD(2017)·36 citations
11. 11*

    Thermal Inflation with Flaton Chemical Potential

    Masato Arai🇯🇵 · Yoshishige Kobayashi🇯🇵 · Nobuchika Okada🇺🇸 · Shin Sasaki🇯🇵

    Thermal inflation driven by a scalar field called "flaton" is a possible scenario to solve the cosmological moduli problem. We study a model of thermal inflation with a flaton chemical potential. In the presence of the chemical potential, a negative mass squared of the flaton, which is necessary to terminate the thermal inflation, is naturally induced. We identify the allowed parameter region for the chemical potential ($\mu$) and the flaton self-coupling constant to solve the cosmological moduli problem and satisfy theoretical consistencies. In general, the chemical potential is a free parameter and it can be taken to be much larger than the typical scale of soft supersymmetry breaking parameters of $\mathcal{O}(1)$ TeV. For $\mu \gtrsim 10^8$ GeV, we find that the reheating temperature after the thermal inflation can be high enough for the thermal leptogenesis scenario to be operative. This is in sharp contrast to the standard thermal inflation scenario, in which the reheating temperature is quite low and a special mechanism is necessary for generating sufficient amount of baryon asymmetry in the Universe after thermal inflation.

    hep-phPRD(2017)·1 citation
12. 12*

    Particularities of the NNLLA BFKL

    V.S. Fadin🇷🇺

    Peculiar properties of the BFKL approach in the next-to-next-to-leading logarithmic approximation (NNLLA) are discussed. In this approximation the scheme of derivation of the BFKL equation must be changed because of violation of the simple factorized form of amplitudes with multi-Reggeon exchanges and necessity to take into account imaginary parts of amplitudes in the unitarity relations.

    hep-phhep-thAIP Conf.Proc.(2017)·43 citations
13. 13*

    Operators up to Dimension Seven in Standard Model Effective Field Theory Extended with Sterile Neutrinos

    Yi Liao (Nankai U., ITP-CAS, CHEP, Peking U.)🇨🇳 · Xiao-Dong Ma (Nankai U.)🇨🇳

    We revisit the effective field theory of the standard model that is extended with sterile neutrinos, $N$. We examine the basis of complete and independent effective operators involving $N$ up to mass dimension seven (dim-7). By employing equations of motion, integration by parts, and Fierz and group identities, we construct relations among operators that were considered independent in the previous literature, and find seven redundant operators at dim-6, sixteen redundant operators and two new operators at dim-7. The correct numbers of operators involving $N$ are, without counting Hermitian conjugates, $16(L\cap B)+1(\text{slashed}L\cap B)+2(\text{slashed}L\cap \text{slashed}B)$ at dim-6, and $47(\text{slashed}L\cap B)+5(\text{slashed}L\cap \text{slashed}B)$ at dim-7. Here $L/B(\text{slashed}L/\text{slashed}B)$ stands for lepton/baryon number conservation (violation). We verify our counting by the Hilbert series approach for $n_f$ generations of the standard model fermions and sterile neutrinos. When operators involving different flavors of fermions are counted separately and their Hermitian conjugates are included, we find there are $29(1614)$ and $80(4206)$ operators involving sterile neutrinos at dim-6 and dim-7 respectively for $n_f=1(3)$.

    hep-phPRD(2017)·211 citations
14. 14*

    Properties of $J/\psi$ in light quark matter

    Martin Cleven🇪🇸 · Volodymyr K. Magas🇪🇸 · Angels Ramos🇪🇸

    With various experiments studying heavy-ion collisions a demand exists in the hadron physics community for theoretical predictions of hadronic properties at temperatures and densities far from equilibrium. In this work we will study the $J/\psi$ vector meson at finite temperatures surrounded by light quark matter. We will apply a chiral unitary approach to account for coupled channels, most importantly channels with open charm. The in-medium solution accounts for the change in self-energy that the $J/\psi$ acquires from interacting with the surrounding light quark matter, most notably pions and rho mesons. The results are preliminary and clearly show the importance of using dressed charmed mesons. Ultimately, the solutions to the corresponding Lippmann-Schwinger Equations are used to calculate observables such as the spectral function of the $J/\psi$.

    hep-phPoS(2016)·0 citations
15. 15*

    Forward $J/\psi$ and $D$ meson nuclear suppression at the LHC

    B. Ducloué🇫🇮 · T. Lappi🇫🇮 · H. Mäntysaari🇺🇸

    Using the color glass condensate formalism, we study the nuclear modification of forward $J/\psi$ and $D$ meson production in high energy proton-nucleus collisions at the LHC. We show that relying on the optical Glauber model to obtain the dipole cross section of the nucleus from the one of the proton fitted to HERA DIS data leads to a smaller nuclear suppression than in the first study of these processes in this formalism and a better agreement with experimental data.

    hep-phnucl-thNucl.Part.Phys.Proc.(2017)·28 citations
16. 16*

    Recovery of hadronic cross section inside the mini black holes at LHC

    Tooraj Ghaffary · Alireza Sepehri · Sayeedul Islam · Farook Rahaman

    In curved space time inside the shell of TeV black holes, many gluons and quarks produce due to Unruh effect, interact with each other and create Higgs boson. Studying the Unruh effect, we show that the inside state of the black hole for gluons and quarks can be represented by a maximally entangled two mode squeezed state of inside and matter Hilbert spaces of black hole. Comparing the Higgs boson production outside and inside the shell, we observe that at lower mass, MBH<4 TeV, and at higher mass, MBH>9 TeV, the Higgs boson will not be produced outside the shell of black hole. However this particle can be produced inside the shell for 2.5 TeV<MBH<12.5 TeV. We find that the outside the shell of black hole is able to produce a quark for 3 TeV<MBH<10 TeV and eventually for MBH<3 TeV and MBH> 12.5 TeV the black hole can only emit massless gluons. However, inside the shell of black hole is able to produce a quark for 2.5 TeV<MBH<14 TeV. We also find that the micro black hole can be a source for Higgs production at LHC. Finally we calculate the effects of Higgs boson radiation due to inside the shell and outside the shell of mini black holes on hadronic cross section at LHC. We observe that as the order of perturbation theory increases, this effect becomes systematically more effective because at higher orders there exists more channels for Higgs production and their decay of Higgs into massive quark-anti quarks in our calculation. At smaller mass, MBH<2 TeV, the NNLO contribution is large while the cross sections at NLO and at LO are rising and respectively exhibit a turn-over at moderate values of black hole's mass.The peak moves from about 5 TeV to 2.5 TeV. It is concluded that the processes of hadronization inside the event horizon of mini black holes are affected the hadronic cross section outside the event horizon and can be observed at LHC.

    hep-phhep-th0 citations
17. 17*

    A simple criterium for CP conservation in the most general 2HDM

    I. F. Ginzburg🇷🇺 · M. Krawczyk🇵🇱

    We find set of necessary and sufficient conditions for CP conservation in the most general 2HDM in terms of observable quantities. This set contains two relatively easily testable simple conditions instead of usually discussed three more complex ones.

    hep-phPRD(2017)·3 citations
18. 18*

    Simulating $b$-associated production of $Z$ and Higgs bosons with SHERPA

    Frank Krauss🇬🇧 · Davide Napoletano🇬🇧 · Steffen Schumann🇩🇪

    We compare four-- and five--flavour scheme predictions for $b$-associated production of $Z$ and Higgs bosons. The results are obtained with \Sherpa's MC@NLOimplementation for the four--flavour scheme, treating the $b$'s as massive, and with multijet merging at leading and next-to leading order for the five--flavour schemes. Comparison with data for $Z+b(\bar{b})$ production at the $7$ TeV LHC exhibit strengths and weaknesses of the different approaches and are used to validate predictions for $b$-associated Higgs-boson production at the 13 TeV Run II.

    hep-phhep-exPRD(2017)·43 citations
19. 19*

    Soft and diffractive scattering with the cluster model in Herwig

    Stefan Gieseke🇩🇪 · Frashër Loshaj🇩🇪 · Patrick Kirchgaeßer🇩🇪

    We present a new model for soft interactions in the event-generator Herwig. The model consists of two components. One to model diffractive final states on the basis of the cluster hadronization model and a second component that addresses soft multiple interactions as multiple particle production in multi- peripheral kinematics. We present much improved results for minimum-bias measurements at various LHC energies.

    hep-phEPJC(2017)·66 citations
20. 20*

    Sterile neutrinos facing kaon physics experiments

    Asmaa Abada🇫🇷 · Damir Becirevic🇫🇷 · Olcyr Sumensari🇫🇷 · Cedric Weiland🇬🇧 · Renata Zukanovich Funchal🇧🇷

    We discuss weak kaon decays in a scenario in which the Standard Model is extended by massive sterile fermions. After revisiting the analytical expressions for leptonic and semileptonic decays we derive the expressions for decay rates with two neutrinos in the final state. By using a simple effective model with only one sterile neutrino, compatible with all current experimental bounds and general theoretical constraints, we conduct a thorough numerical analysis which reveals that the impact of the presence of massive sterile neutrinos on kaon weak decays is very small, less than $1\%$ on decay rates. The only exception is $\mathcal{B}(K_L\to \nu \nu )$, which can go up to $\mathcal{O}(10^{-10})$, thus possibly within the reach of the KOTO experiment. In other words, if all the future measurements of weak kaon decays turn out to be compatible with the Standard Model predictions, this would not rule out the existence of massive light sterile neutrinos with non-negligible active-sterile mixing. Instead, for a sterile neutrino of mass below $m_K$, one might obtain a huge enhancement of $\mathcal{B}(K_L\to \nu \nu )$, otherwise negligibly small in the Standard Model.

    hep-phhep-exhep-latPRD(2017)·34 citations
21. 21*

    Muon bundles as a sign of strangelets from the Universe

    P. Kankiewicz🇵🇱 · M. Rybczynski🇵🇱 · Z. Wlodarczyk🇵🇱 · G. Wilk🇵🇱

    Recently the CERN ALICE experiment, in its dedicated cosmic ray run, observed muon bundles of very high multiplicities, thereby confirming similar findings from the LEP era at CERN (in the CosmoLEP project). Originally it was argued that they apparently stem from the primary cosmic rays with a heavy masses. We propose an alternative possibility arguing that muonic bundles of highest multiplicity are produced by strangelets, hypothetical stable lumps of strange quark matter infiltrating our Universe. We also address the possibility of additionally deducing their directionality which could be of astrophysical interest. Significant evidence for anisotropy of arrival directions of the observed high multiplicity muonic bundles is found. Estimated directionality suggests their possible extragalactic provenance.

    hep-phastro-ph.HEnucl-thApJ(2017)·20 citations
22. 22*

    Dark Matter Relics and the Expansion Rate in Scalar-Tensor Theories

    Bhaskar Dutta🇺🇸 · Esteban Jimenez🇺🇸 · Ivonne Zavala🇬🇧

    We study the impact of a modified expansion rate on the dark matter relic abundance in a class of scalar-tensor theories. The scalar-tensor theories we consider are motivated from string theory constructions, which have conformal as well as disformally coupled matter to the scalar. We investigate the effects of such a conformal coupling to the dark matter relic abundance for a wide range of initial conditions, masses and cross-sections. We find that exploiting all possible initial conditions, the annihilation cross-section required to satisfy the dark matter content can differ from the thermal average cross-section in the standard case. We also study the expansion rate in the disformal case and find that physically relevant solutions require a nontrivial relation between the conformal and disformal functions. We study the effects of the disformal coupling in an explicit example where the disformal function is quadratic.

    hep-phastro-ph.COgr-qchep-thJCAP(2017)·27 citations
23. 23*

    Holographic Preheating

    Yi-Fu Cai🇨🇳 · Shu Lin🇨🇳 · Junyu Liu🇺🇸 · Jia-Rui Sun🇨🇳

    We propose a holographic description of cosmic preheating at strong coupling. In this scenario the energy transfer between the inflaton and matter field is mimicked by a model of holographic superconductor. An exponential amplification of the matter field during preheating can be described by the quasi-normal modes of a metastable "black hole" in the bulk spacetime with an expanding boundary. Our results reveal that the matter field can be produced continuously at strong coupling in contrast to the case of weak coupling with a discontinuous matter growth as inflaton oscillates. Furthermore, the amplification of matter field has an enhanced dependence on the vacuum expectation value of the inflaton at strong coupling. By virtue of the proposed mechanism, physics of the very early universe at an extremely high temperature right after inflation may become accessible.

    ↳ hep-thastro-ph.COgr-qchep-phJ.Univ.Sci.Tech.China(2020)·6 citations
24. 24*

    Lattice Calculation of Nucleon Isovector Axial Charge with Improved Currents

    Jian Liang🇺🇸 · Yi-Bo Yang🇺🇸 · Keh-Fei Liu🇺🇸 · Andrei Alexandru🇺🇸 · Terrence Draper🇺🇸 · Raza Sabbir Sufian🇺🇸

    We employ dimension-4 operators to improve the local vector and axial-vector currents and calculate the nucleon isovector axial coupling $g_A^3$ with overlap valence on $2+1$-flavor Domain Wall Fermion sea. Using the equality of $g_A^3$ from the spatial and temporal components of the axial-vector current as a normalization condition, we find that $g_A^3$ is increased by a few percent towards the experimental value. The excited-state contamination has been taken into account with three time separations between the source and sink. The improved axial charges $g_A^3(24I)=1.22(4)$ and $g_A^3(32I)=1.21(3)$ are obtained on a $24^3\times 64$ lattice at pion mass of 330 MeV and a $32^3\times 64$ lattice at pion mass 300 MeV are increased by $3.4\%$ and $1.7\%$ from their unimproved values, respectively. We have also used clover fermion on the same DWF configurations and find the same behavior for the local axial charge as that of the overlap fermion.

    ↳ hep-lathep-phPRD(2017)·46 citations
25. 25*

    Holographic Preheating: Quasi-Normal Modes and Holographic Renormalization

    Yi-Fu Cai🇨🇳 · Shu Lin🇨🇳 · Junyu Liu🇺🇸 · Jia-Rui Sun🇨🇳

    In the holographic description of cosmic preheating proposed in an accompanied Letter [1], the energy transfer between the inflaton and matter field at strong coupling is suggested to be mimicked by superfluid and normal components of a superconductor on Friedmann-Robertson-Walker (FRW) boundary in an asymptotically Anti-de Sitter (AdS) spacetime. In this paper we investigated two aspects of the scenario of holographic preheating that are not included in the accompanied work. Firstly, we study in detail the evolution of the quasi-normal modes (QNMs) surrounding a metastable hairy black hole. This analysis can quantitatively describe the preheating process of the matter field that is produced continuously in the case of strong coupling. Secondly, we present a detailed analysis of the holographic renormalization for the AdS-FRW background, which allows us to extract operator expectation values for studying cosmological implications.

    ↳ hep-thastro-ph.COgr-qchep-phJ.Univ.Sci.Tech.China(2020)·7 citations
26. 26*

    Split Q-Balls

    D. Bazeia🇧🇷 · L. Losano🇧🇷 · M.A. Marques🇧🇷 · R. Menezes🇧🇷

    We investigate the presence of non-topological solutions of the Q-ball type in (1, 1) spacetime dimensions. The model engenders the global U(1) symmetry and is of the k-field type, since it contains a new term, of the fourth-order power in the derivative of the complex scalar field. It supports analytical solution of the Q-ball type which is stable quantum mechanically. The new solution engenders an interesting behavior, with the charge and energy densities unveiling a splitting profile.

    ↳ hep-thhep-phPLB(2017)·23 citations
27. 27*

    Random Potentials and Cosmological Attractors

    Andrei Linde🇺🇸

    I show that the problem of realizing inflation in theories with random potentials of a limited number of fields can be solved, and agreement with the observational data can be naturally achieved if at least one of these fields has a non-minimal kinetic term of the type used in the theory of cosmological $\alpha$-attractors.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2017)·35 citations
28. 28*

    Behavior of universal critical parameters in the QCD phase diagram

    Marcus Bluhm (North Carolina State U.)🇺🇸 · Marlene Nahrgang (SUBATECH, Nantes and Duke U.)🇫🇷 · Steffen A. Bass (Duke U.)🇺🇸 · Thomas Schaefer (North Carolina State U.)🇺🇸

    We determine the dependence of important parameters for critical fluctuations on temperature and baryon chemical potential in the QCD phase diagram. The analysis is based on an identification of the fluctuations of the order parameter obtained from the Ising model equation of state and the Ginzburg-Landau effective potential approach. The impact of the mapping from Ising model variables to QCD thermodynamics is discussed.

    ↳ nucl-thhep-phJ.Phys.Conf.Ser.(2017)·8 citations
29. 29*

    Quark chiral condensate from the overlap quark propagator

    Chao Wang🇨🇳 · Yujiang Bi🇨🇳 · Hao Cai🇨🇳 · Ying Chen🇨🇳 · Ming Gong🇨🇳 · Zhaofeng Liu🇨🇳

    From the overlap lattice quark propagator calculated in the Landau gauge, we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data. The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with $N_f=2+1$ flavors. Three ensembles with different light sea quark masses are used at one lattice spacing $1/a=1.75(4)$ GeV. We obtain $⟨\bar{\psi }\psi {⟩}^{\overline{\mathrm{MS}}}(2\text{mbox}GeV)=(-305(15)(21)\text{mbox}MeV{)}^3$ in the SU(2) chiral limit.

    ↳ hep-lathep-phCPC(2017)·13 citations
30. 30*

    Novel applications of Lattice QCD: Parton distribution functions, proton charge radius and neutron electric dipole moment

    Constantia Alexandrou (Univ. of Cyprus and The Cyprus Inst.)🇨🇾

    We briefly discuss the current status of lattice QCD simulations and review selective results on nucleon observables focusing on recent developments in the lattice QCD evaluation of the nucleon form factors and radii, parton distribution functions and their moments, and the neutron electric dipole moment. Nucleon charges and moments of parton distribution functions are presented using simulations generated at physical values of the quark masses, while exploratory studies are performed for the parton distribution functions and the neutron electric dipole moment at heavier than physical value of the pion mass.

    ↳ hep-lathep-phnucl-exnucl-thEPJ Web Conf.(2017)·15 citations
31. 31*

    On model-independent searches for direct CP violation in multi-body decays

    Chris Parkes🇬🇧 · Shanzhen Chen🇬🇧 · Jolanta Brodzicka🇬🇧 · Marco Gersabeck🇬🇧 · Giulio Dujany🇬🇧 · William Barter🇬🇧

    Techniques for performing model-independent searches for direct CP violation in three and four-body decays are discussed. Comments on the performance and the optimisation of a binned chisquare approach and an unbinned approach, known as the energy test, are made. The use of the energy test in the presence of background is also studied. The selection and treatment of the coordinates used to describe the phase-space of the decay are discussed. The conventional model-independent techniques, which test for P-even CP violation, are modified to create a new approach for testing for P-odd CP violation. An implementation of the energy test using GPUs is described.

    ↳ hep-exhep-phJ.Phys.G(2017)·27 citations
32. 32*

    The role of fluctuation-dissipation dynamics in setting initial conditions for inflation

    Mar Bastero-Gil🇪🇸 · Arjun Berera🇬🇧 · Robert Brandenberger🇨🇦 · Ian G. Moss🇬🇧 · Rudnei O. Ramos🇧🇷 · Joao G. Rosa🇵🇹

    We study the problem of initial conditions for slow-roll inflation along a plateau-like scalar potential within the framework of fluctuation-dissipation dynamics. We consider, in particular, that inflation was preceded by a radiation-dominated epoch where the inflaton is coupled to light degrees of freedom and may reach a near-equilibrium state. We show that the homogeneous field component can be sufficiently localized at the origin to trigger a period of slow-roll if the interactions between the inflaton and the thermal degrees of freedom are sufficiently strong and argue that this does not necessarily spoil the flatness of the potential at the quantum level. We further conclude that the inflaton can still be held at the origin after its potential begins to dominate the energy balance, leading to a period of thermal inflation. This then suppresses the effects of nonlinear interactions between the homogeneous and inhomogeneous field modes that could prevent the former from entering a slow-roll regime. Finally, we discuss the possibility of an early period of chaotic inflation, at large field values, followed by a first stage of reheating and subsequently by a second inflationary epoch along the plateau about the origin. This scenario could prevent an early overclosure of the Universe, at the same time yielding a low tensor-to-scalar ratio in agreement with observations.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·35 citations
33. 33*

    Chaotic initial conditions for nonminimally coupled inflation via a conformal factor with a zero

    Jinsu Kim🇰🇷 · John McDonald🇬🇧

    Nonminimally coupled inflation models based on a nonminimal coupling $\xi {\varphi }^{2}R$ and a ${\varphi }^4$ potential are in excellent agreement with the scalar spectral index observed by Planck. Here we consider the modification of these models by a conformal factor with a zero. This enables a nonminimally coupled model to have a Planck-scale potential energy density at large values of the inflaton field, which can account for the smooth, potential-dominated volume that is necessary for inflation to start. We show that models with a conformal factor zero generally predict a correlated increase of the spectral index $n_s$ and tensor-to-scalar ratio $r$. For values of $n_s$ that are within the present $2-\sigma$ bounds from Planck, modification by $\Delta r$ as large as 0.0013 is possible, which is large enough to be measured by next generation cosmic microwave background polarization satellites.

    ↳ astro-ph.COhep-phhep-thPRD(2017)·4 citations
34. 34*

    Holographic Photon Production and Anisotropic Flow

    Ioannis Iatrakis🇳🇱 · Elias Kiritsis🇫🇷 · Chun Shen🇺🇸 · Di-Lun Yang🇯🇵

    The thermal-photon emission from strongly coupled gauge theories at finite temperature via the bottom-up models in holographic QCD in the deconfined phase is studied. The models are constructed to approximately reproduce the electric conductivity obtained from lattice simulations for the quark gluon plasma (QGP). The emission rates are then embedded in hydrodynamic simulations combined with prompt photons and hadronic contributions to analyze the spectra and anisotropic flow of direct photons in RHIC and LHC. In general, the holographic models enhance the yield and improve the agreement in spectra, while they reduce the flow in low $p_T$ and increase it in high $p_T$.

    ↳ nucl-thhep-phhep-thNucl.Part.Phys.Proc.(2017)·3 citations

* 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.