KYOTO (Japan) - JAPANESE Nobel Physics laureate Toshihide Maskawa, an introvert devoted to thinking about the universe, has no passport to go to Stockholm to accept the prize, his wife revealed on Wednesday.

Professor Masakawa, 68, was one of three physicists to share the prestigious award announced on Tuesday for his groundbreaking work on fundamental particles.

But his wife, Akiko, said that Prof Maskawa does not travel overseas and feels 'quite allergic to trying to speak English.'

'And if he needs to go to the award ceremony, he'll need first to apply for a passport,' she said at her home in the western city of Kyoto, where Dr Maskawa is a professor of theoretical physics at Kyoto Sangyo University.

Prof Maskawa, bespectacled with grey hair, charmed reporters after the prize was announced by trying to conceal his shyness, at one point sobbing and at another moment forcing such a grin that he stuck out his tongue.

He also raised his arms over his head and said to eager reporters, 'You'd like me to do this to show I'm happy, right?'

He earlier told reporters abruptly that he was 'not that happy' about receiving the Nobel Prize, which will be handed out at a ceremony in Stockholm on December 10.

'It's just a society party', he said.

But he backtracked on Wednesday.

'I play the devil's advocate, so when somebody tells me to look left, I look right,' he said with a big smile.

'As a scientist, I feel the most pleased when fellow scientists tell me I was right,' he said. 'Of course I get happy when I get compliments.'

Every time Prof Maskawa was invited abroad to receive an award or make a speech, Prof Makoto Kobayashi, who shared the Nobel Prize with him, went instead.

In the 1970s, Prof Maskawa and Prof Kobayashi came up with a theory on why antimatter sometimes does not obey the same rules as matter. They found that nature had three families of quarks, an elementary particle.

The third winner to share the prize was Prof Yoichiro Nambu, a Japanese-born American of the University of Chicago, for his groundbreaking theories on the nature of subatomic particles and how they move.

Laureates receive a gold medal, a diploma and 10 million Swedish kronor (S$2.08 million). -- AFP