arXiv subjects

Jogesh C. Pati

Publications and source records attributed to Jogesh C. Pati.

25 records · Page 2Linked to original sources

arXiv1996

The Essential Role of String-Derived Symmetries in Ensuring Proton-Stability and Light Neutrino Masses

The paper addresses the problem of suppressing naturally the unsafe d=4 as well as the color-triplet mediated and/or gravity-linked d=5 proton-decay operators, which generically arise in SUSY-unification. It also attempts to give light masses to the neutrinos, of the type suggested by current experiments. It is noted that neither the symmetries in $SO(10)$, nor those in $E_6$, suffice for the purpose -- especially in the matter of suppressing naturally the d=5 proton-decay operators. By contrast, it is shown that a certain {\it string-derived symmetry}, which cannot arise within conventional grand unification, but which does arise within a class of three-generation string-solutions, suffices, in conjuction with $B-L$, to safeguard proton-stability from all potential dangers, including those which may arise through higher dimensional operators and the color-triplets in the infinite tower of states. At the same time, the symmetry in question permits neutrinos to acquire appropriate masses. This shows that {\it string theory plays an essential role in ensuring natural consistency of SUSY-unification with two low-energy observations -- proton-stability and light masses for the neutrinos}. The correlation between the masses of the extra $Z'$-boson (or bosons), which arise in these models, and proton-decay rate is noted.

hep-ph↗

arXiv1996

The problems of unification-mismatch and low $α_3$: A solution with light vector-like matter

The commonly accepted notion of a weak unified coupling $α_X \approx 0.04$, based on the assumption of the MSSM--spectrum, is questioned. It is suggested that the four--dimensional unified string coupling should very likely have an intermediate value $(\sim 0.2-0.3$, say) so that it may be large enough to stabilize the dilaton but not so large as to disturb the coupling--unification relations. Bearing this in mind, as well as the smallness of the MSSM unification scale $M_X$ compared to the string scale, the consequences of a previously suggested extension of the MSSM spectrum are explored. The extension contains two vector--like families of quarks and leptons with relatively light masses of order 1 TeV, having the quantum numbers of ${\bf 16}+{\bf \overline{16}}$ of $SO(10)$. It is observed that such an extension provides certain unique advantages. These include: (a) removing the stated mismatch between MSSM and string unifications with regard to $α_X$ and to some extent $M_X$ as well, (b) achieving coupling unification with a relatively low value of $α_3(m_Z)$, in accord with its world average value, and (c) following earlier works, providing a simple explanation of the observed inter--family mass--hierarchy. The extension provides scope for exciting new discoveries, beyond those of SUSY and Higgs particles, at future colliders, including the LHC and the NLC.

hep-ph↗

arXiv1995

The Role of Gravity in Determining Physics at High as Well as Low Energies

It is noted that in the context of a supersymmetric preonic approach to unification, gravity, though weak, can play an essential role in determining some crucial aspects of low-energy physics. These include: (i) SUSY-breaking, (ii) electroweak symmetry-breaking, and (iii) generation of masses of quarks and leptons, all of which would vanish if we turn off gravity. Such a role of gravity has its roots in the Witten index theorem which would forbid SUSY-breaking, within the class of theories under consideration, in the absence of gravity.

hep-ph↗

arXiv1995

BOSE-FERMI SYMMETRY: A CRUCIAL ELEMENT IN ACHIEVING UNIFICATION

This talk is dedicated to honor the memory of Professor S.N. Bose. I survey the crucial roles played by Bose-Fermi symmetry in all recent attempts at higher unification, which include the ideas of (i) the conventional approach to grand unification; (ii) the preonic approach; and (iii) superstrings.

hep-ph↗

arXiv1995

Indirect Neutrino Oscillations

We show how two different scales for oscillations between $e$ and $μ$ neutrinos, characterized by different mixing angles and effective mass scales, can arise in a simple and theoretically attractive framework. One scale characterizes direct oscillations, which can accommodate the MSW approach to the solar neutrino problem, whereas the other can be considered as arising indirectly, through virtual transitions involving the $τ$ neutrino with a mass $\sim$ 1 eV. This indirect transition allows the possibility of observable $\bar ν_μ\leftrightarrow \bar ν_e$ oscillations at accelerator and reactor energies. We discuss specifically the parameters suggested by a recent experiment at Los Alamos within this framework.

hep-ph↗

arXiv1995

TOWARDS A UNIFIED ORIGIN OF FORCES, FAMILIES, AND MASS SCALES

A case is made for an alternative approach to unification that is based on a {\it purely gauge origin of the fundamental forces}, and is thus devoid of the Higgs-sector altogether. This approach seems to call for the ideas of local supersymmetry and preons. The advantage of this marriage of the ideas of local supersymmetry and preons, subject to two broad dynamical assumptions which are specified, are noted. These include true economy and viability as well as an understanding of the origins of (a) family-replication, (b) inter-family mass-hierarchy, and (c) diverse mass-scales which span from $M_{Planck}$ to $m_W \sim m_t$ to $m_e$ to $m_ν$. In short, the approach seems capable of providing {\it a unified origin of the forces, the families and the mass-scales}. In the process, the preonic approach provides the scope for synthesizing a rich variety of phenomena all of which could arise dynamically through one and the same tool -- the SUSY metacolor force coupled with gravity -- at the scale of $10^{11}GeV$. The phenomena include: (i) spontaneous violations of parity, CP, B-L and Peccei-Quinn symmetry, (ii) origin of heavy Majorana mass for $ν_R$, (iii) SUSY breaking, (iv) origins of even $m_W,~m_q$ and $m_\ell$, as well as, (v) inflation and lepto/baryo-genesis. Some intriguing experimental consequences of the new approach which could show at LEPI, LEPII and Tevatron and a {\it crucial prediction} which can be probed at the LHC and NLC are presented.

hep-ph↗

arXiv1994

"A Hint From the Inter-Family Mass Hierarchy: Two Vector-Like Families in the TeV range"

Two vector-like families with masses of order 1 TeV, one of which is a doublet of $SU(2)_L$ and the other a doublet of $SU(2)_R$, have been predicted to exist in the context of a viable and economical SUSY composite model. One of the many attractive features of the model is an explanation of the inter-family mass-hierarchy for which the existence of the two vector-families is crucial. This paper is devoted to a detailed study of the expected masses, mixings and decay modes of the fermions belonging to the two vector-like families. The masses of the vector-like quarks are expected to lie in the range of 500 GeV to about 2.5 TeV, while those of the vector-like leptons are expected to be in the range of 200 GeV to 1 TeV. Their mass pattern and decay modes exhibit certain distinguishing features and characteristic signals. For example, when the LHC and, possibly a future version of the SSC are built, pair-production of the vector-like quarks would lead to systems such as ($b\overline{b}+4Z+W^+W^-$) and ($b\overline{b}+2Z+W^+W^-$), while an $e^-e^+$ linear collider (NLC) of suitable energy can produce appreciably a single neutral heavy lepton $N$ together with $ν_τ$, followed by the decay of $N$ into $(Z+ν_τ) \rightarrow (e^-e^+) + ν_τ$. This last signal may conceivably materialize even at LEP 200 if $N$ is lighter than about 190 GeV.

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